Bioactive polymers 66. Theophylline retardation in xanthan-based hydrogels.

Xanthan has been reticulated with epichlorohydrin to obtain a hydrogel for use in drug retardation. The obtained gel shows swelling degrees up to 1000. Theophylline has been inserted by diffusion into this gel; concentrations around 150 mg theophylline/g dry hydrogel being obtained. Controlled release of theophylline has been established by elution in a close recirculation system. Zero-order kinetics has been obtained in the diffusion process of theophylline into the eluent, within a 14 h time interval.

Bioactive polymers XXXIII. Synthesis and evaluation of some pharmacological characteristics of chloramphenicol immobilized on Biozan R.

The coupling of chloramphenicol on Biozan R (Hercules) by activation with dicyclohexylcarbodiimide was studied. The esterification is influenced by the chloramphenicol/dicyclohexylcarbodiimide ratio, concentration of the reactants and reaction time. The Biozan R-chloramphenicol system containing 15% chloramphenicol was used to obtain ophthalmic ointments. They were studied from the point of view of their physicochemical and biological properties. Tests were performed on animals and volunteers to establish the ophthalmic tolerance; some clinical observations on treated eyes were also made.

Bioactive polymers. LX. Kinetics of delayed release neomycin-xanthan complex.

The kinetics of delayed release neomycin-xanthan complex, and its antimicrobial activity, were studied. Delayed release neomycin (53.13% free neomycin) had zero-order release kinetics, when artificial tear solution was used as eluent. Microbiological tests revealed an activity of 380 units/mg, 10% higher than neomycin in its free form.

Lipase immobilization into porous chitoxan beads: activities in aqueous and organic media and lipase localization.

Lipases were noncovalently immobilized in Chitoxan, a polyionic hydrogel obtained by complexation between chitosan and xanthan. The properties of free and immobilized lipases have been compared. In the aqueous medium, the activity was twice as high for immobilized lipases as for free lipases. Immobilized lipases in chitoxan were able to hydrolyze triacylglycerols in three distinct organic solvent media. At the microstructural level, lipases were not distributed uniformly in the chitoxan beads. Higher concentrations of lipase were found in the outer membrane-like layer of the beads, as compared with lower concentrations in the inner part of the beads.

Susceptibility testing of Streptococcus mitis group isolates.

BACKGROUND & OBJECTIVES: Suppurative oral and maxillofacial infections are usually mixed infections due to aerobic and anaerobic bacteria, most frequently by oral streptococci and antimicrobial treatment is necessary for such infections. The aim of this study was to investigate the antimicrobial susceptibility of Streptococcus mitis group strains isolated from Romanian patients with different oral and maxillofacial infections. METHODS: Eighty-five isolates belonging to S. mitis group isolated from pus samples were identified at species level by the Rapid ID 32 STREP system. The E test was used to determine the susceptibilities of the isolates to penicillin, ampicillin, cefotaxime, erythromycin, clindamycin, chloramphenicol and tetracycline. RESULTS: Of the 151 samples studied, 85 isolates belonged to S. mitis group. The minimum inhibitory concentration (MIC) values (mg/l) ranged from 0.016-0.75 for penicillin, 0.016-2 for ampicillin, 0.016- 1 for cefotaxime, 0.016-4 for erythromycin, 0.016-0.047 for clindamycin, 0.5-4 for chloramphenicol and 0.047-256 for tetracycline. INTERPRETATION & CONCLUSION: The low susceptibility and the resistance to some commonly used antibiotics found in this study indicated a need for a careful surveillance of the susceptibility pattern of oral streptococci isolates of clinical significance. Clindamycin and chloramphenicol might be suitable alternative agents in treatment of oral and maxillofacial infections involving penicillin-resistant bacteria and in case of patients with hypersensitivity to beta-lactam antibiotics.

Bioactive polymers 53: synthesis of poly(vinyl alcohol) and nalidixic acid based pro-drugs.

The present paper studies the process of esterification of nalidixic acid on poly(vinyl alcohol). The influence of time, dilution and concentration of the reactants on the efficiency of esterification with dicyclohexylcarbodiimide has been followed. By experiment scheduling according to a centered, rotatory, compound, second order program, optimum conditions for the system under study have been found. On the other hand, the evolution of reaction of esterification of the nalidixic acid on poly(vinyl alcohol) was followed by using the activator-catalyst (4-pirolidinopyridine) system. An increase of the esterification yield up to 37% has been observed.

Bioactive polymers 55. Synthesis and characterization of a macromolecular drug based on 5-acetylamino-2-sulfamoyl-1,3,4-thiodiazole.

The paper studies the coupling reaction by covalent bonding of acetylamino-2-sulfamoyl-1,3,4-thiodiazole (AcAA) on the poly(acrylic acid-costyrene) copolymer (PAcA-S) in homogeneous system, in the presence of dicyclohexylcarbodiimide (DCC) as activator. The influence of some factors on coupling efficiency (the drug/support ratio, time, volume of solvent), as well as the mathematical model correlating the amount of coupled drug with these parameters is established. Maximum amounts of drug (28%) are chemically bound when employing maximum values of the parameters mentioned (i.e., AcAA/PAcA-S ratio = 2 mole/mole; time = 50 h; THF volume = 60 ml). Physicochemical and spectral analyses evidence the existence of some chemical bonds of the -CO-NH-SO2-type between the macromolecular support and the drug. In vivo tests have demonstrated the gradual hydrolysis of the chemical bonds as well as the release of the drug, due to the diuretic effect produced.

Bioactive polymers 68--controlled release of neomycin-furazolidone bicomponent system from xanthan hydrogel.

The neomycin-furazolidone-xanthan complex has been synthesized. Neomycin is covalently linked to xanthan, while furazolidone is inserted in the hydrogel formed by the reaction between neomycin and xanthan. The content of neomycin and furazolidone depends on the drug rate in the reaction medium. Thus, a zero-order kinetics is obtained for the release of both neomycin and furazolidone in basic medium. The complex's antimicrobial activity is intensified.

Bioactive polymers: in vitro and in vivo study of controlled release neomycin.

Neomycin is coupled on xanthan-a polysaccharide of microbial biosynthesis produced by Xanthomonas campestris-through ionic complexation. The kinetics of neomycin release, in vitro, at pH = 8.2 is studied. A controlled release of neomycin, following a zero order kinetics is observed, regardless of the eluent flow. Neomycin complexed on xanthan, administered in a unique daily dose to patients suffering from dysentery in the 100 cases taken in study, has shown a high clinical efficiency as compared with the treatments with ampicillin or furazolidone, administered for 5-10 days or longer.

Bioactive polymers 54. Pharmacological properties of modified neomycin.

Modified neomycin prepared by the ionic coupling on xanthan with an activity of 380 UI/mg was characterized in regard to its in vitro and in vivo release rate and therapeutic action with artificial tear eluent. The dynamic system in vitro release showed that after 4 h, there appears a "zero-order" kinetic. Ophthalmic inserts were prepared from modified neomycin and they are used in treating bacterial conjunctivitis. Sterilization of the conjunctival sac is obtained 12 h after insert administration.

Bioactive polymers. 70. The kinetics of controlled release of neomycin in an alkaline medium.

Neomycin is coupled on xanthan--a polysaccharide of microbial biosynthesis produced by Xanthomona campestris--through ionic complexation. The kinetics of neomycin release, in vitro, at pH = 8.2 is studied. A release of neomycin, following a zero order kinetics, is observed, regardless of the eluent flow-rate. The neomycin-xanthan complex, protected by a cellulosic membrane, behaves like a monolithic-type device. Diffusion coefficients--increasing with increasing the eluent flow-rate--are also calculated.

Isolation and speciation of Prevotella strains from periodontal abscesses.

The aims of the study were to isolate and to identify at species level the Prevotella strains in pus samples collected by needle aspiration from 25 Romanian patients with periodontal abscesses. Gram-stained smears and cultures on selective and nonselective media were performed from each of the 25 pus samples. The isolates were identified on the basis of Gram staining, cultural characteristics and standard biochemical reactions. The Gram-negative anaerobic bacilli isolates were biochemically characterized and identified at species level using the Rapid ID 32 A system (Bio Mérieux, France). Fifteen Prevotella isolates belonging to one of the following species: P. melaninogenica, P. denticola, P. oralis, P. loescheii and P. bivia were recovered. All Prevotella isolates reacted similarly in 20 tests in the Rapid ID 32 A system. The P. melaninogenica strain showed approximately the same biochemical profile and only two sugar fermentation tests were not constantly positive. The study confirmed that Prevotella is often involved in periodontal abscesses (> 50% of the cases) in association with other anaerobic or/and aerobic bacteria. P. melaninogenica was the most frequently isolated Prevotella species from the investigated cases.

Streptococci species of anginosus group isolated from oral and maxillofacial infections.

The aim of the study was to isolate and identify at species level streptococci strains of anginosus group in pus samples collected from 110 patients with oral and maxillofacial (OMF) infections. Gram-stained smears and cultures on selective and nonselective media were done from each of the 111 pus samples (2 samples were collected from one of the patients, who presented 2 oral abscesses at the same time). The isolates were identified on the basis of cultural and biochemical characteristics. Speciation of the anginosus group isolates was performed using the Rapid ID 32 Strep system (Bio Mérieux, France). Fourty-four anginosus group strains were isolated from 42 patients. Fourty of these isolates were identified as Streptococcus anginosus (2 nonidentical isolates were found in 2 patients), 3 isolates as Streptococcus constellatus and only one as Streptococcus intermedius. The study confirmed that the anginosus group is often involved in OMF infections alone or in association with other aerobic and/or anaerobic bacteria. In the investigated cases, Streptococcus anginosus was by far the most frequently isolated species within the anginosus group.

Antimicrobial susceptibility of some streptococci strains of anginosus group isolated from oral and maxillofacial infections.

Streptococci strains of the anginosus group isolated from various oral and maxillofacial infections (OMF) were screened for their susceptibility to the following antimicrobial agents: benzylpenicillin, ampicillin, oxacillin, cephalothin, ceftazidime, cefotaxime, cefuroxime, erythromycin, clindamycin, tetracycline, chloramphenicol, vancomycin and trimethoprime-sulphamethoxazole. The isolates were susceptable to: clindamycin, chloramphenicol, vancomycin and all beta-lactam antibiotics, except ceftazidime to which 54.5% of the strains showed intermediate susceptibility. Intermediate susceptibility to tetracycline was found in 11.3% of the strains, whereas resistance to the same antibiotic was demonstrated in 61.4%. Resistance to erythromycin and trimethoprime-sulphamethoxazole was of 2.3% for both. In conclusion, penicillin is the drug of choice in infections caused by streptococci of the anginosus group.

Phenotypic characterization of some anginosus group isolates from oral and maxillofacial infections.

The aim of this study was to briefly characterize serologically, biochemically and from the cultural point of view some anginosus group isolates found in pus samples collected from patients with oral and maxillofacial infections. Cultural characterization was done by studying the culture odor, the colony size and aspect, and hemolysis type on Columbia bood agar (BA). Lancefield grouping was made on cards using the rapid latex-agglutination test (Slidex Strepto-Kit, Bio Mérieux, France). The biochemical characterization was performed at the same time with the speciation by the Rapid ID 32 Strep system (Bio Mérieux, Marcy-l'Etoile, France). The anginosus group isolates were phenotypically heterogenic. Based on phenotypic description, nonidentical anginosus group isolates were found in the same patient sample.

[Passive hemagglutination test in the serodiagnosis of syphilis]. / Reactia de hemaglutinare pasiva în serodiagnosticul sifilisului.

Passive haemagglutination test with pathogenic Treponema pallidum antigen in the serodiagnosis of syphilis, carried out on 752 sera (518 syphilitic patients and 234 subjects without evidence of syphilis) showed a greater general sensitivity as compared the cardiolipin tests and complement fixation test with Reiter protein antigen, and lower, to immunofluorescence (FTA--ABS). Its specificity is relatively lower than that of the cardiolopin and treponemal tests. Associated with the cardiolipin test it may be preferably used for the detection of syphilis, and moreover, passive haemagglutination may confirm the diagnosis in case of weak positive results with the FTA--ABS test. The latter is, however, essential for problem cases.

Bioactive polymers. 56: urease immobilization on carboxymethylcellulose.

This article reports on the reaction of urease immobilization through its covalent bonding on carboxymethylcellulose. The reaction is activated by dicyclohexylcarbodiimide. The coupling reaction is influenced by the enzyme-support and activator-support ratios, as well as by duration. Starting from a rotating, composed experimental program of the second order, the function correlating the activity of the immobilized enzyme with the reaction parameters is established. Immobilized urease exhibits thermal stability higher than that of free enzyme, regarding both pH and the inhibiting action of some metal ions or organic substances. The stability over time of the immobilized urease is high, its enzymatic activity being maintained at over 85% of the initial value three months after synthesis.

Bioactive polymers XXX. Immobilization of invertase on the diazonium salt of 4-aminobenzoylcellulose.

Invertase was immobilized on diazotized 4-aminobenzoylcellulose. The optimum coupling conditions, namely enzyme concentration, time, and pH, were determined. The temperature and pH value for the maximum activity of the immobilized enzyme were determined and the apparent Michaelis constant was estimated.

[Apiphytotherapeutic original preparations in the treatment of chronic marginal parodontopathies. A clinical and microbiological study]. / Preparate originale apifitoterapeutice in tratamentul parodontopatiilor marginale cronice. Studiu clinic si microbiologic.

The paper presents results obtained by the treatment of chronic marginal parodontopathies with natural products of apiarian derivatives and vegetal extracts. These are original preparations such as Proparodont, sage extracts, watercress extracts, etc., by comparison with other similar existing products, and with zinc chloride. The clinical study evaluated the "inflammation status of the marginal prodontium" on the basis of variations in the PMA index. The microbiological study has established the bacteriostatic and the bactericidal activities of the products employed. The results obtained stress the high antimicrobial activity of the original products called Proparodont, and stress its antimycotic effects, especially against Candida albicans. The blackwort (Symphytum off.) extracts have a good repair effect, especially after surgical procedures. The complex original products based on propolis and vegetal extracts are indicated in the treatment of inflammatory lesions of the gingivo-parodontal tissues, and of the buccal mucosa. They also have antimicrobial effects, as well as antimycotic, antiinflammatory and antiscar effects. They de not have side effects which are characteristic for other medicinal drugs employed in the treatment of chronic marginal parodontopathies.

Inclusion and release of proteins from polysaccharide-based polyion complexes.

The notion of a polyelectrolyte complex is well established for the complexation of two polymers one anionic, the other cationic. Electronic microscopy studies have shown the formation of a fibrilar structure. A method for the preparation of polyionic hydrogels from the complexation of chitosan and xanthan is reported. Electronic microscopy studies have shown the formation of a fibrilar structure. Stable hydrogels have been used to immobilize xylanase, lipase and protease. The immobilized xylanase and lipase activity was significantly higher than that of the free enzyme.