Neomycin Research Articles

Kontaktallergien gegen ophthalmologische Lokaltherapeutika – eine epidemiologische Risikobewertung

Contact allergies (CA) against active agents of topical ophthalmological therapeutics, causing inflammation of the conjunctiva and/or the lid, are usually not life-threatening, but occur not infrequently. As yet, the assessment of the CA-eliciting risk has been based on clinical data alone, while a valid epidemiological risk assessment is lacking. The Information Network of Departments of Dermatology supplied information on diagnostic results obtained in 4,102 patients patch-tested for suspected CA to ophthalmic drugs between 1995 and 2004. Clinical prevalences were extrapolated to incidences at the German population level. These estimates served as numerator for a relative incidence (RI), which included the nationwide frequency of prescriptions collected by the WIdO, Bonn, in terms of a standardised defined daily dose (DDD) as denominator. The estimated annual incidence of CA ranges from 155 (atropine sulphate) to 2077 (gentamicin sulphate) and can thus be regarded as moderate. If incidence estimates are related to prescription frequencies, the highest risk was found for kanamycin and neomycin sulphate (RI > 8 / 100,000 DDD). In contrast, the RI of pilocarpine-HCl (0.3) was virtually negligible. The substance-specific risk of CA has been evaluated for the first time and found to differ between therapeutics (with a similar spectrum of application). CA risk should be considered in differential therapeutic decision-making.

THE ANTIBIOTIC RESISTANCE PHENOMENON IN CITROBACTER STRAINS ISOLATED FROM ANIMALS

The therapeutic choice of an antibiotic have to take into account, firstly, the ethiological agent, an also the susceptibility of this pathogen to antibiotics. Microorganisms from Micrococcus genus were isolated from animals and were identified using bacterioscopic and bacteriologic techniques, then were investigated through agar diffusion method about the susceptibility to different groups of antibiotics. The results of this study were interpreted according to the international standards and compared to the work of other researchers. Susceptibility of 100 % was registered for spectinomycin and tetracicline. It was found 66,66 % percentage of the bacterial strains to be sensitive to amoxicillin and 50 % to ampicillin, penicillin and only 33,33 % to potentiated sulfonamide. But the highest percentage of antibacterial resistance (100 %) was observed for flumequine and neomycin, followed by trimethoprim/sulphamethoxazole – 66,66 %, erytromycin – 60 % (in addition, 40 % intremediary strains) and penicillin (in addition, 50 % intermediary strains), ampicillin, kanamycin – 50 % . Although there were no reports of resistance to amoxicillin for the Micrococcus genus in this study, 33,33 % of the strains registered intermediary values for the inhibition areas around the microcomprimates, and 66 % of the bacterial strains presented susceptibility to this antibiotic. In conclusion, we recommend spectinomycin and tetracycline as the first choice for the Micrococcus genus strains, followed by penicillins, according to the results of this study.

Study regarding response to antimicrobial agents of Salmonella enterica strains, isolated from various ecological areas.

Between 2006 - 2008, we collected 106 Salmonella from birds (79 isolates) and pigs (27 isolates). These isolates were tested for susceptibility by antimicrobial disk diffusion method (Kirby –Bauer), according to NCCLS guidelines (1). The most sensitive drug for S. enterica tested were enrofloxacine (95.2%), ceftriaxone (93.3%), trimetroprim-sulfametoxazole (86.7%), ceftazidime (85.8%), ampiciline - sulbactam (83.9%), gentamycin (81.1%) and minimal values of sensibility were recorded for nitrofurantoine (3.8%), furazolidon (4.7%), nalidixic acid (5.6%), neomycin (6.6 %), flumequin (6.6%). tetracycline (7.5%).

Displacer concentration effects in displacement chromatography: Implications for trace solute detection

In this paper, the utility of ion-exchange displacement chromatography for the concentration and enrichment of trace proteins is examined. Separations with varying displacer concentrations (1–25 mM neomycin sulfate) indicate that higher concentrations result in elevated protein concentrations, at the price of reduced yields. The results demonstrate that displacement chromatography carried out at relatively low displacer concentrations (2.5 mM) can produce significant concentration (8.5-fold) and enrichment (18-fold) of trace proteins present in the feed. Parametric simulations using the steric mass action model are carried out to investigate the concentration effects and enrichment factors observed over a wide range of feed, displacer and buffer counter-ion concentrations, and solute separation factors. The simulations confirm that trace components can be readily concentrated and enriched by displacement chromatography and that these effects will be more pronounced as the separation factor between trace and abundant components is increased. The results presented in this paper indicate the potential of displacement chromatography for improved separations where trace enrichment is critical such as proteomic applications.

Porous bovine hydroxyapatite for drug delivery.

Biomaterials derived from natural sources have considerable interest in human health care. This study reports a simple method of designing a bone drug delivery system using porous bovine hydroxyapatite (BHA). The porous BHA blocks with different porosity were fabricated by a die-pressing method using polyvinylbutyral (PVB) as a porosifier. A model antibiotic drug, neomycin sulfate (NS) was loaded in the blocks and its in vitro release performance was studied. Fourier transform infrared (FTIR) analysis provided qualitative proof of drug molecule entrapment in the BHA blocks. The in vitro evaluation of the drug indicated that the rate of drug loading and release was directly proportional to the porosity of the blocks.

En bloc combined liver and small-bowel transplantation in rats: construction of a cuff in portal vein

Objective To establish a model of en bloc combined liver/small bowel transplanta-tion in the rat. Methods Homoplastic transplantation of en bloc combined liver and small-bowel in Wistar rats was performed. As for the donor operation, the portal vein and superior mesenteric artery were flushed with 4℃ cold Ringer's solution. The small intestinal lumen was flushed with 4℃ cold Ne-omycin solution. The donor small bowel and liver were harvested, preserved and transplanted as a whole. The donor inferior vena eava in abdomen was cut to construct a muff in the lateral wall of por-tal vein and cuff was placed. For the recipient operation, the orthotopie liver transplantation was com-pleted at first by using Kamada's two cuff technique, and then the donor abdominal aorta was anasto-mosed end to side to the receptor abdominal aorta artery to set up superior mesenteric artery and prop-er hepatic artery blood flow under a microscope. The lower ileum was exteriorized as stoma in right lower abdomen. Results The successful rate of operation was 86 %. The mean survival time of the grafted rats was over 30 d. The transplanted liver and small bowel were normal in histology. Conclu-sion It is feasible to establish a model of en bloc combined liver and small bowel transplantation by constructing a cuff in portal vein. Key words: Liver transplantation; Liver; Small bowel; Rat

Contact Allergy in Children Referred for Patch Testing

To determine the frequency of positive and relevant patch tests in children referred for patch testing in North America; to compare results of patch testing children and adults; and to compare our results with international data on contact allergy in children. Retrospective cross-sectional analyses of North American Contact Dermatitis Group (NACDG) data from January 1, 2001, through December 31, 2004. Patch test reactions for allergens that were positive and considered of clinical importance to the patient's eczematous problem were defined as being of current or past relevance. Clinical patch test data from 13 NACDG members, primarily a referral population. The pediatric population (hereafter referred to as "children") was defined as patients aged 0 to 18 years (n = 391). Patients 19 years and older constituted the comparison adult group (n = 9670). The frequency of positive patch test reactions and number of relevant ones. Secondary measures included the association of atopic markers, frequency of irritant reactions, and sources of relevant supplementary allergens. No significant difference in the overall frequency of at least 1 relevant positive patch test reaction was noted in children (51.2%) compared with adults (54.1%). The most frequent positive reactions in children were to nickel (28.3%), cobalt chloride (17.9%), thimerosal (15.3%), neomycin sulfate (8.0%), gold sodium thiosulfate (7.7%), and fragrance mix (5.1%). For children aged 0 to 18 the most frequent relevant positive reactions were to nickel sulfate (26.0%), cobalt (12.4%), neomycin (4.4%), fragrance mix (4.1%), gold (3.6%), and quaternium 15 (3.6%). The frequency of irritant reactions in adults and children was similar. Of the children with a relevant positive reaction, 34.0% had atopic dermatitis included as one of their final diagnoses, compared with 11.2% of adults (P < .001). Fifteen percent and 39% of children had relevant allergens not included in the NACDG series and a commercially available skin patch test (T.R.U.E. TEST [thin-layer rapid use epicutaneous test], panel 1.1 and 2.1; Allerderm, Phoenix, Arizona), respectively. Adults and children in this group are equally likely to have allergic contact dermatitis; frequency of relevant allergen reactions differs.

Stimulation by cochlear implant in unilaterally deaf rats reverses the decrease of inhibitory transmission in the inferior colliculus

In the last decade, numerous studies have investigated synaptic transmission changes in various auditory nuclei after unilateral cochlear injury. However, few data are available concerning the potential effect of electrical stimulation of the deafferented auditory nerve on the inhibitory neurotransmission in these nuclei. We report here for the first time the effect of chronic electrical stimulation of the deafferented auditory nerve on alpha1 subunit of the glycinergic receptor (GlyRalpha1) and glutamic acid decarboxylase (GAD)67 expression in the central nucleus of inferior colliculus (CIC). Adult rats were unilaterally cochleectomized by intracochlear neomycin sulphate injection. Fifteen days later, the ipsilateral auditory nerve was chronically stimulated either 4, 8 or 22 h daily, for 5 days using intracochlear bipolar electrodes. GlyRalpha1 and GAD67 mRNA and protein were quantified in the CIC using in situ hybridization and immunohistofluorescence methods. Our data showed that as after surgical ablation, GlyRalpha1 and GAD67 expression were strongly decreased in the contralateral CIC after unilateral chemical cochleectomy. Most importantly, these postlesional down-modulations were significantly reversed by chronic electrical stimulation of the deafferented auditory nerve. This recovery, however, did not persist for more than 5 days after the cessation of the deafferented auditory nerve electrical stimulation. Thus, downregulations of GlyRalpha1 and GAD67 may be involved both in the increased excitability observed in the CIC after unilateral deafness and consequently in the tinnitus frequently observed in unilateral adult deaf patients. Electrical stimulation of the deafferented auditory nerve in patients may be a potential new approach for treating tinnitus with unilateral hearing loss.

Contact allergy in patients with rosacea: a clinic‐based, prospective epidemiological study

Rosacea is a relatively common inflammatory skin disease of unknown prevalence. The proportion of contact allergy complicating rosacea and its therapy, respectively, is largely unknown. To estimate the prevalence of specific contact allergy in rosacea patients and to compare this with the prevalence observed in the general population and in general patch test patients. In this prospective monocentre study, 78 patients with rosacea were investigated for contact sensitizations via patch testing the standard series, constituents of topical formulations, preservatives, fragrances, topically applied drugs and, if available, patient's own products. Positive reactions occurred to nickel (II) sulphate (12 of 78, 15.4%), fragrance mix I (4 of 77, 5.2%), balsam of Peru (8 of 77, 10.4%; significantly elevated prevalence compared to that observed in the population-based KORA study), potassium dichromate (4 of 78, 5.1%) and Lyral (3 of 78, 3.8%). Regarding topical antibiotics, only 1 of 78 (1.3%) patients was positive to neomycin sulphate, and none to metronidazole; however, 6 of 75 (8%) patients were positive to gentamicin sulphate, and 4 of 76 (5.3%) patients were positive to framycetin sulphate. No allergic but irritant patch test reactions, instead, were provoked by various patients' own products as well as by the irritant sodium lauryl sulphate (SLS) even in low concentrations. Despite the limited power of the study, a strikingly high prevalence of contact allergy to gentamicin sulphate was observed, which is probably due to antibiotic treatment of rosacea-associated eye symptoms. The reactions to the irritant SLS probably mirror the extreme skin sensitivity in rosacea.

Periorbital dermatitis-a recalcitrant disease: causes and differential diagnoses

Periorbital dermatitis is common and frequently recalcitrant to treatment. Due to the exposed and visible location, patients often suffer severely from periorbital dermatitis. To determine the frequency and causes of periorbital dermatitis including contact sensitizers. We investigated two cohorts of patients (Erlangen and IVDK without Erlangen) between 1999 and 2004. The differences between the two cohorts with periorbital dermatitis [Department of Dermatology at University Hospital Erlangen (n = 88) and the German Information Network of Departments of Dermatology (IVDK) collective (n = 2035)] were determined by the MOAHLFA (male, occupational dermatosis, atopic eczema, hand dermatitis, leg dermatitis, facial dermatitis, age > or = 40 years) index. Statistically significant factors for periocular eczema are female sex, atopic skin diathesis and age > or = 40 years. In both cohorts allergic contact dermatitis was the main cause of periorbital eczema (Erlangen 44.3%, IVDK 31.6%), followed by periorbital atopic dermatitis (Erlangen 25%, IVDK 14.1%), airborne dermatitis (Erlangen 10.2%, IVDK 1.9%), irritant contact dermatitis (Erlangen 9.1%, IVDK 7.6%), periorbital rosacea (Erlangen 4.5%, IVDK 2.2%), allergic conjunctivitis (Erlangen 2.3%, IVDK included in 'others') and psoriasis (Erlangen 2.3%, IVDK included in 'others'). The most relevant allergens/allergen sources inducing periorbital eczema were consumers' products (facial cream, eye shadow and ophthalmic therapeutics) (31%), fragrance mix (19%), balsam of Peru (10%), thiomersal (10%) and neomycin sulphate (8%); 12.5% of patients with allergic periocular dermatitis could be exclusively elucidated by testing patients' own products. Our data demonstrate the multiplicity of causes for periorbital eczematous disease manifestation, which requires patch testing of standard trays as well as consumers' products to elucidate the relevant contact sensitization.

Associations between baseline allergens and polysensitization

Identification of patients at risk of developing polysensitization is not possible at present. An association between weak sensitizers and polysensitization has been hypothesized. To examine associations of 21 allergens in the European baseline series to polysensitization. From a database-based study with 14 998 patients patch tested with the European baseline series between 1985 and 2005, a group of 759 (5.1%) patients were polysensitized. Odds ratios were calculated to determine the relative contribution of each allergen to polysensitization. Seven allergens--parabens mix, N-isopropyl-N-phenyl-p-phenylenediamine, sesquiterpene lactone mix, wool alcohols, potassium dichromate, Myroxylon pereirae, and cobalt chloride - showed statistically significant positive associations to polysensitization. Five allergens p-phenylenediamine, neomycin sulfate, epoxy resin, primin, and nickel sulfate showed statistically significant negative associations to polysensitization. For the allergens with the strongest associations, only every second individual with these particular allergies had two or more additional allergies. No common denominator for the association between the allergens and the polysensitization was apparent, and any association, whether positive or negative, was relatively low. Based on these results, sensitization to specific baseline allergens cannot be used as risk indicators for polysensitization.

A double-blind randomised clinical trial of the treatment of otitis externa using topical steroid alone versus topical steroid–antibiotic therapy

The objective of the study was to determine if the addition of topical antibiotic increases the efficacy of topical steroid in controlling otitis externa. A double-blind randomised controlled trial was performed from February 2003 to April 2005 in an otolaryngology emergency clinic (acute urban teaching hospital) in the United Kingdom. Patients were followed up for 2 weeks. Forty-five adults with otitis externa based on the presence of oedema, discharge or debris in the outer ear canal were recruited. The patients were randomised to one of the two treatment groups, namely using betamethasone sodium phosphate 0.1% (Vista-Methasone) or betamethasone sodium phosphate 0.1% with neomycin sulphate 0.5% (Vista-Methasone N), and were instructed to use the trial medication at three drops three times a day for 2 weeks. Subjects' visual analogue symptom scores (blockage, pain, discharge, and itching) for otitis externa pre-treatment (day 0) and post-treatment (day 15), percentage changes in visual analogue symptom scores as a result of treatment, proportion of patients whose symptom scores failed to improve or deteriorated on treatment were analysed. The two experimental arms demonstrated statistically similar presenting symptom scores at recruitment (mean symptom scores of 19.2 for betamethasone group and 28.7 for betamethasone-neomycin group). The mean symptom score change in response to treatment was 82.8 and 47.8% in the betamethasone-neomycin and betamethasone-alone groups, respectively. There was no statistically significant difference between the groups in median percentage symptom score change in response to treatment. All patients in the betamethasone-neomycin group showed symptom improvement but in the betamethasone alone group, five patients got worse (Fishers exact, P = 0.05). Topical antibiotic-steroid combination therapy is superior to steroid-alone treatment for symptomatic control of otitis externa.

Effect of a combination of medium chain triglycerides, linoleic acid, soy lecithin and vitamins A and E on wound healing in rats

The aim of the study was to determine the effect of a combination of medium chain triglycerides (caprylic, capric, caproic and lauric acids), linoleic acid (essential fatty acid), vitamins A and E and soy lecithin, through a morphometric study, on the wound healing kinetics of experimental cutaneous ulcers. A total of 45 male Wistar rats were used, in which a skin flap of total thickness with an area of 4 cm2 was removed. The animals were divided randomly into 3 groups of 15 rats each, Control, Reference and Test groups, which were treated topically with 0.9% NaCl, a preparation of clostebol combined with neomycin sulfate and the test formulation, respectively. The wound areas were measured by digital planimetry at days zero, 3, 7 and 12 postoperative. Based on the wound area, we determined the degree of tissue repair and mean rate of repair at different time intervals. At day 3, an expansion of the wound area was observed in the Reference group and slight contraction in the Control and Test groups. On the subsequent days, the healing process, according to the degree of repair, proceeded in a linear manner, such that, at day 12, the healed area reached 77.95% of the initial ulcerated region in the Control group, 78.40% in the Reference group and 83.49% in the Test group, showing no significant differences. The overall mean rate of repair was equally similar at 12 days of treatment: 25.79 mm2/dia in the Control group, 25.42 mm2/dia in the Reference group and 27.38 mm2/dia in the Test group. The test preparation, applied topically on the experimentally induced cutaneous ulcers in rats, did not accelerate the process of tissue repair by secondary union.

Delayed patch test reading after 5 days: The Mayo Clinic experience

Some patients may have delayed allergic patch test reactions that are not identified with a typical 5-day reading protocol. To identify allergens with delayed-positive reactions and to determine whether a late reading (day 7-9) can be substituted for the day-5 reading. We retrospectively reviewed medical records of patients who underwent patch testing for suspected allergic contact dermatitis from October 1997 through December 2006 and returned for delayed readings between days 7 and 10 or beyond. (This cohort was predominantly patients with suspected allergies to metals and corticosteroids). A total of 36,064 individual reactions (471 allergens, 372 patients) were interpreted on day 5 and at least once during days 7 through 21. We analyzed the 170 allergens that were each tested in at least 50 patients. The 4 allergens with the highest percentage of delayed-positive reactions were gold sodium thiosulfate 0.5% (delayed-positive reactions in 22/353 patients), dodecyl gallate 0.25% (6/105), palladium chloride 2% (8/194), and neomycin sulfate 20% (10/253). We observed a low number of delayed-positive readings for p-phenylenediamine 1% (1/251) and for corticosteroids. Reactions to certain preservative and fragrance allergens dissipated after the day-5 reading. Most reactions that dissipated after day 5 were mild, whereas the reactions that became apparent after day 5 were strong. This was a retrospective study. Most patients had suspected allergies to metals and corticosteroids. Late patch test readings (day 7 or beyond) were useful when interpreting reactions to metals and topical antibiotics, but it was not useful in the diagnosis of reactions to other allergens, including topical corticosteroids. Because reactions to certain fragrance and preservative allergens may dissipate after 5 days, patch test reactions therefore are optimally read at days 3 and 5, but an additional reading on day 7 or beyond is useful if patch tests to metals and topical antibiotics are performed.

Whole organ culture of the postnatal sensory inner ear in simulated microgravity

Among the three major biological in vitro models, cell culture, tissue culture, and organ culture, the latter provides the closest approximation to the in vivo situation, but also requires the most demanding culture conditions. Due to its small size and complex tissue architecture, the mammalian inner ear provides a particular challenge to the development of whole organ culture. Using a rotating bioreactor system with simulated microgravity conditions, the entire mouse inner ear organ can be maintained in culture for up to seven days with preservation of sensory organ morphology and robust marker protein expression in sensory hair cells. Controlled sensory cell lesions can be induced by the ototoxic agent, neomycin sulphate, as a toxicologic model of hair cell degeneration and hair cell loss. The results demonstrate that simulated microgravity organ culture of the inner ear affords an in vitro model for the investigation of developmental, regulatory, and differentiation processes, as well as toxicological, biotechnological, and pharmaceutical screening applications within the normal and pathologic sensory hearing organ.

BSAC standardized disc susceptibility testing method (version 7)

The changes that have been made to the previous version of the recommendations (version 6) are as follows: medium and incubation condition for testing Acinetobacter spp. (Tables 1 and 6); use of cefoxitin as an indicator antibiotic for detecting methicillin/oxacillin/cefoxitin resistance in coagulase-negative staphylococci (Tables 1, 6 and 11); MIC breakpoint for co-trimoxazole based on the trimethoprim concentration in a 1:19 combination with sulfamethoxazole (Tables 7, 10, 11, 12, 15, 16 and 19); advice on the use of azithromycin for the treatment of infections with Salmonella typhi (footnote to Table 7); amendment to the recommendation for cefuroxime for the treatment of infections with Proteus mirabilis (footnote Table 7); MIC and zone diameter breakpoints for Stenotrophomonas maltophilia only (Table 10); MIC breakpoints for daptomycin (Tables 11 and 15); clarification for staphylococci that the neomycin zone diameter breakpoints are for topical use only and differentiate the isolates outside the 'wild-type' population in Table 11; clarification for beta-haemolytic streptococci that the linezolid zone diameter breakpoints relate to an MIC breakpoint of 2 mg/L as no data for the intermediate category are currently available (Table 15); clarification that strains with reduced susceptibility to fluoroquinolones give no zone of inhibition with a 30 microg nalidixic acid disc (Tables 16 and 21); erythromycin is no longer used for therapy of Neisseria gonorrhoeae, but may be tested for epidemiological purposes (Table 17); clarification that the ciprofloxacin zone diameter breakpoint for Neisseria meningitidis relates to the MIC breakpoint of 0.03 mg/L as no data for the intermediate category are currently available; clarification that the ciprofloxacin zone diameter breakpoints for Campylobacter spp. relate to an MIC breakpoint of 0.5 mg/L as no data for the intermediate category are currently available; clarification that for ciprofloxacin and vancomycin zone diameter breakpoints for coryneform organisms relate to an MIC breakpoint of 0.5 and 4 mg/L, respectively, as no data for the intermediate category are currently available; MIC and zone diameter breakpoints for Gram-negative rods isolated from urinary tract infections have been expanded to include Klebsiella spp.; and a definition of coliforms is also included (Table 26).

A Comparison of the Polycation Receptors of Paramecium tetraurelia and Tetrahymena thermophila

Chemorepellents are compounds that cause ciliated protozoans to reorient their swimming direction. A number of chemorepellents have been studied in the ciliated protozoans, Paramecium and Tetrahymena. Chemorepellents, such as polycations, cause the organism to exhibit "avoidance behavior," a swimming behavior characterized by jerky movements and other deviations from normal forward swimming, which result from ciliary reversal. One well-characterized chemorepellent pathway in Tetrahymena is that of the proposed polycation receptor that is activated by lysozyme and pituitary adenylate cyclase activating polypeptide (PACAP). In this study, we compare the response of Paramecium to the chemorepellents lysozyme, vasoactive intestinal peptide (VIP), and PACAP to the previously studied polycation response in Tetrahymena. Our results indicate that lysozyme, VIP, and PACAP are all chemorepellents in Paramecium, just as they are in Tetrahymena. However, the signaling pathways involved appear to be different. While previous pharmacological characterization indicates that G-proteins are involved in polycation signaling in Tetrahymena, we present evidence that similar reception in Paramecium involves activation of a tyrosine kinase pathway in order for lysozyme avoidance to occur. Polycation responses of both organisms are inhibited by neomycin sulfate. While PACAP is the most effective of the three chemorepellents in Tetrahymena, lysozyme is the most effective chemorepellent in Paramecium.

Foot eczema: the role of patch test in determining the causative agent using standard series.

Foot dermatitis refers to the predominant involvement of feet in the eczematous process. This study is undertaken to determine the clinical pattern and causative agent in foot eczema and to evaluate the role of patch testing in determining the causative agent of foot eczema. Data was collected from 50 patients with foot eczema, who attended the out-patient department. The patch test was performed using Indian standard series. Patch test was positive in 88% of the patients. The most common site affected was the dorsal aspect of the foot (48%) and scaly plaque was the predominant morphological pattern. The highest number of patients (24%) showed positive reactions to mercaptobenzothiazole (MBT) and the lowest (4%) to neomycin sulfate. Rubber and rubber chemicals have been reported worldwide to be the most common sensitizer causing foot eczema. Thus, patch test has a major role in finding out the cause of foot eczema.

Spectroscopic and electrochemical characterization of cytochrome c encapsulated in a bio sol–gel matrix

Sol-gel technique represents a remarkably versatile method for protein encapsulation. To enhance sol-gel biocompatibility, systems envisaging the presence of calcium and phosphates in the sol-gel composition were recently prepared and investigated. Unfortunately, the low pH at which solutions were prepared (pH < 2.5) dramatically limited their application to proteins, because the acidic environment induces protein denaturation. In this paper we apply a new protocol based on the introduction of calcium nitrate to the inorganic phase, with formation of a binary bioactive system. In this case protein encapsulation results versatile and secure, being achieved at a pH close to neutrality (pH 6.0); also, the presence of calcium is expected to enhance system biocompatibility. To determine the properties of the salt-doped sol-gel and the influence exerted on entrapped biosystems, the structural and functional properties of embedded cytochrome c have been investigated. Data obtained indicate that the salt-doped sol-gel induces no significant change in the structure and the redox properties of the embedded protein; also, the matrix increases protein stability. Interestingly, the presence of calcium nitrate appears determinant for refolding of the acid-denatured protein. This is of interest in the perspective of future applications in biosensoristic area.

Susceptibility of bacterial pathogens against lincomycin/spectinomycin (1/2), penicillin G/neomycin (1/1), and penicillin G/dihydrostreptomycin (1/1) as determined in the BfT-GermVet monitoring program 2004-2006.

A total of 368 bacterial pathogens, including 72 coagulase-positive and coagulase-variable staphylococci, 97 beta-haemolytic streptococci, 51 Escherichia coli, 75 Pasteurella multocida, 25 Mannheimia haemolytica, 25 Pseudomonas aeruginosa, and 23 Arcanobacterium pyogenes, were investigated for their susceptibility to the three combinations of antimicrobial agents lincomycin/spectinomycin (1/2), penicillin G/neomycin (1/1), and penicillin G/dihydrostreptomycin (1/1) in comparison to their susceptibility to the corresponding single substances. When comparing the minimum inhibitory concentrations (MICs) determined for any of the three combinations with those for the single substances, the lowest MIC of one of the two substances usually determined the MIC of the combination.This observation was made for all three combinations and all bacterial pathogens tested.Thus, it is assumed that the combination of lincomycin with spectinomycin as well as that of penicillin with either neomycin or dihydrostreptomycin resulted in an extended spectrum of target bacterial pathogens rather than in an increase in antimicrobial efficacy.