Nanosilver-loaded PMMA bone cement doped with different bioactive glasses - evaluation of cytocompatibility, antibacterial activity, and mechanical properties.

Nanosilver-loaded PMMA bone cement (BC-AgNp) is a novel cement developed as a replacement for conventional cements. Despite its favorable properties and antibacterial activity, BC-AgNp still lacks biodegradability and bioactivity. Hence, we investigated doping with bioactive glasses (BGs) to create a new bioactive BC characterized by time-varying porosity and gradual release of AgNp. The BC Cemex was used as the base material and modified simultaneously with the AgNp and BGs: melted 45S5 and 13-93B3 glasses with various particle sizes and sol-gel derived SiO2/CaO microparticles. The effect of BG addition was examined by microscopic analysis, an assessment of setting parameters, wettability, FTIR and UV-VIS spectroscopy, mechanical testing, and hemo- and cytocompatibility and antibacterial efficiency studies. The results show that it is possible to incorporate various BGs into BC-AgNp, which leads to different properties depending on the type and size of BGs. The smaller particles of melted BGs showed higher porosity and better antibacterial properties with the moderate deterioration of mechanical properties. The sol-gel derived BGs, however, displayed a tendency for agglomeration and random distribution in BC-AgNp. The BGs with greater solubility more efficiently improve the antibacterial properties of BC-AgNp. Besides, the unreacted MMA monomer release could negatively influence the cellular response. Despite that, cements doped with different BGs are suitable for medical applications.

Influence of several biodegradable components added to pure and nanosilver-doped PMMA bone cements on its biological and mechanical properties.

Acrylic bone cements (BC) are wildly used in medicine. Despite favorable mechanical properties, processability and inject capability, BC lack bioactivity. To overcome this, we investigated the effects of selected biodegradable additives to create a partially-degradable BC and also we evaluated its combination with nanosilver (AgNp). We hypothesized that using above strategies it would be possible to obtain bioactive BC. The Cemex was used as the base material, modified at 2.5, 5 or 10 wt% with either cellulose, chitosan, magnesium, polydioxanone or tricalcium-phosphate. The resulted modified BC was examined for surface morphology, wettability, porosity, mechanical and nanomechanical properties and cytocompatibility. The composite BC doped with AgNp was also examined for its release and antibacterial properties. The results showed that it is possible to create modified cement and all studied modifiers increased its porosity. Applying the additives slightly decreased BC wettability and mechanical properties, but the positive effect of the additives was observed in nanomechanical research. The relatively poor cytocompatibility of modified BC was attributed to the unreacted monomer release, except for polydioxanone modification which increased cells viability. Furthermore, all additives facilitated AgNp release and increased BC antibacterial effectiveness. Our present studies suggest the optimal content of biodegradable component for BC is 5 wt%. At this content, an improvement in BC porosity is achieved without significant deterioration of BC physical and mechanical properties. Polydioxanone and cellulose seem to be the most promising additives that improve porosity and antibacterial properties of antibiotic or nanosilver-loaded BC. Partially-degradable BC may be a good strategy to improve their antibacterial effectiveness, but some caution is still required regarding their cytocompatibility. STATEMENT OF SIGNIFICANCE: The lack of bone cement bioactivity is the main limitation of its effectiveness in medicine. To overcome this, we have created composite cements with partially-degradable properties. We also modified these cements with nanosilver to provide antibacterial properties. We examined five various additives at three different contents to modify a selected bone cement. Our results broaden the knowledge about potential modifiers and properties of composite cements. We selected the optimal content and the most promising additives, and showed that the combination of these additives with nanosilver would increase cements` antibacterial effectiveness. Such modified cements may be a new solution for medical applications.

[Intensity modulated radiotherapy for head and neck cancers: ethics and patients selection]. / Radiothérapie conformationnelle avec modulation d'intensité dans les cancers de la sphère ORL : éthique et sélection des patients.

PURPOSE: Intensity modulated radiotherapy (IMRT) allows a better coverage of the target volume and a better saving of organs at risk with a decrease of toxicity in head and neck cancers. It requires more human labor and materials compared to conformational radiotherapy. If they are insufficient, a selection of the patients receiving IMRT may be necessary, raising an ethical problem. MATERIAL AND METHODS: We collected the motives guiding the choice of the technique of radiotherapy for head and neck cancers during a month of physicists' shortage. RESULTS: Nineteen patients received IMRT and eight conformational radiotherapy. Conformational irradiation was chosen in palliative and postsurgery treatments, to reduce delay, in laryngeal tumors and re-irradiation. IMRT was preferred for complex target volumes and the localizations at risk of important xerostomia following conformational radiotherapy. These choices were confronted with the bioethics criteria of Beauchamp and Childress. The beneficence justified the use of IMRT or conformational radiotherapy depending on the circumstances. The non-maleficence attempted to decrease the toxicity with IMRT. Justice was questioned by the selection. The autonomy of patients was not totally respected in the choice. CONCLUSION: To help in the choice of the patients receiving an IMRT in a crisis situation, we proposed a hierarchical organization of selection criteria: complex volumes close to critical organs at risk, localization with high risk of xerostomia, long life expectancy and postoperative delay constraints.

Epidemiology of meningococcal meningitis and changes in the surveillance system in Poland, 1970-2006.

The objective of this study was to describe the general features of meningococcal meningitis epidemiology in 1970-2006 in Poland, in the context of changes made in surveillance system methods. Because of limited availability of case-based data, a more detailed analysis was performed only for the period 1994-2006 with special focus on case-fatality and diagnostic certainty. The reported annual number of meningococcal meningitis cases reached its peak of 416 (incidence 1.2 per 100,000) in 1981, after which it decreased to 76 cases in 2003 (incidence 0.2), and then increased to 151 cases in 2006 (incidence 0.4 per 100,000). The observed decrease was consistent with the decline in the number of live births and the drop in mortality from meningococcal disease observed using an independent reporting of death certificates. In 1994-2006, 1,677 cases of meningococcal meningitis were registered, with annual incidence varying between 0.2 and 0.5 per 100,000 inhabitants. Median age of patients was 4 years and 73% of cases were under 18 years of age. The majority of cases were caused by group B meningococci, but a trend towards increasing proportion of serogroup C has been identified. Meningococcal meningitis only was reported in 79% of cases, and meningitis with concomitant septicaemia in 21%. The overall case fatality was 3.7% - 4.5% in cases of meningitis only, and 7.1% in cases of meningitis with septicaemia. Based on the case definition introduced in 2005, 88.1% of the cases would be classified as confirmed and 4.8% as probable, whereas 7.1% would not fulfil the criteria of the case definition. Although diagnostic certainty of reported cases has improved in recent years, it is still problematic. Further efforts are needed to increase the proportion of serogrouped cases and assess the burden of meningococcal disease in Poland.

Network structure, and vaccination strategy and effort interact to affect the dynamics of influenza epidemics.

There is growing interest in understanding and controlling the spread of diseases through realistically structured host populations. We investigate how network structures, ranging from circulant, through small-world networks, to random networks, and vaccination strategy and effort interact to influence the proportion of the population infected, the size and timing of the epidemic peak, and the duration of the epidemic. We found these three factors, and their higher-order interactions, significantly influenced epidemic development and extent. Increasing vaccination effort (from 0% to 90%) decreased the number of hosts infected while increasing network randomness worked to increase disease spread. On average, vaccinating hosts based on degree (hubs) resulted in the smallest epidemics while vaccinating hosts with the highest clustering coefficient resulted in the largest epidemics. In a targeted test of five vaccination strategies on a small-world network (probability of rewiring edges=5%) with 10% vaccination effort we found that vaccinating hosts preferentially with high-clustering coefficients (similar to real-world strategies) resulted in twice the number of hosts infected as random vaccinations and nearly a 30-fold higher number of cases than our strategy targeting hubs (highest degree hosts). Our model suggests how vaccinations might be implemented to minimize the extent of an epidemic (e.g., duration and total number infected) as well as the timing and number of hosts infected at a given time over a wide range of structured host networks.

Evaluation of tickborne encephalitis case classification in Poland.

Central European tickborne encephalitis (TBE) is a viral disease of the central nervous system. Despite a surveillance system for TBE existing in Poland since 1970, there are no standardised case definitions and different diagnostic tests are used in various regions. The purpose of this study was to summarise four years of surveillance data using standardised case definitions. From 1999 to 2002, 607 cases of TBE were reported to Poland's national surveillance system: 386 (63.6%) were males, 331 (54.5%) lived in rural areas, and 186 (30.6%) were between 30 and 50 years old. Of 606 diagnosed cases, 453 (74.7%) had aseptic meningitis, 109 (18.0%) had meningoencephalitis, and 44 (7.3%) had meningoencephalomyelitis. Of the 607 reported cases, 602 (99.2%) could be classified: 153 (25.4%) as confirmed, 343 (57.0%) as probable, and 106 (17.6%) as possible cases. There was a significant difference in classified cases by gender: 28.6% of male cases were classified as confirmed, compared with 19.7% of female cases (chi2= 10.48, p=0.0053). There was a significant difference in case classification by clinical diagnosis: 32.4% of cases with meningoencephalitis were classified as confirmed cases, compared with 24.7% of cases with aseptic meningitis (chi2=11.79, p=0.019). There were also significant differences in the distribution by case definition group across geographical regions. For appropriate monitoring of TBE, a uniform and valid case definition should be used in European countries. With only 25% of reported cases meeting the definition for confirmed cases, there is a need for more complete follow-up and standardised testing of suspect cases.

Congenital blepharoptosis: Part I. Evaluation of the results of surgical treatment for congenital blepharoptosis.

A retrospective clinical analysis of 69 of 118 patients with congenital blepharoptosis aged from 2 to 48, who underwent surgical corrections at the Department of Plastic Surgery of Lódz between 1977 and 2001, was reviewed. Included cases were analysed on the base of the type of primary defect, degree of ptosis, and surgical method. The aim of this study was to estimate aesthetic and functional results of surgical treatment in 39 patients corrected by Mustarde's modified method, in 17 by Mustarde's method, in 7 by Everbusch's method, in 4 by Blascovic's method, and in 2 by frontalis suspension. Comparable acceptable results of Mustarde's modified and Mustarde's method were achieved. Postoperatively 13 patients (18.8%) exhibited lagophthalmos.

Congenital blepharoptosis: Part II. Visual disorders coexisting with congenital blepharoptosis.

A retrospective ophthalmic analysis 44 of 118 patients with congenital blepharoptosis aged from 2 to 48, who underwent surgical correction at the Department of Plastic Surgery of Lódz between 1977 and 2001, was reviewed. Patients with congenital blepharoptosis were investigated by ophthalmologists in the pre and postoperative period, and their medical ophthalmological notes were also analysed. The aim of this study was to assess the presence, type, and severity of visual disorders coexisting with ptosis. We found in 42 patients (95%) ophthalmologic disorders, of which we noted amblyopia in 19, astigmatism in 30, anisometropia in 5, and strabismus in 30 cases.

[Tetanus in Poland in 1999]. / Tezec w 1999 roku.

In last decade gradual decrease in numbers of reported cases of tetanus was observed. In 1999, 21 cases of tetanus (14 women and 7 men) were reported in Poland. All those cases were among people of age 40 or more. 23.8% of cases died. Case fatality increased with age. In more than 90% vaccination status of cases was unknown. The data show effectiveness of vaccination program in younger age groups, but they also show need for promotion of post exposure prophylaxis, especially among older people both in rural and in urban areas. No case of neonatal tetanus was noted in Poland since 1984.

[Epidemiological assessment of an effectiveness of vaccinations]. / Epidemiologiczne badanie efektywnosci szczepien.

The study deals with the notion of the effectiveness of vaccination in relation to vaccine efficacy and the performance of the vaccination programs. The types of epidemiological studies used in assessment of vaccine effectiveness are presented and listed are the most common sources of bias in those studies. Basic formulas for calculation of vaccine efficiency coefficient are given as applied for cohort and case-control studies. Ways of estimation of vaccine effectiveness in outbreaks of epidemics are presented in relation to the degree of vaccine coverage and herd immunity effect. Effectiveness is analyzed as one of the many aspects in evaluation of the epidemiological impact of vaccinations.

[Studies of effectiveness of vaccination against pertussis during 1997-1998 outbreak in Poland]. / Skutecznosc szczepien przeciw krztuscowi w okresie epidemii 1997-1998 w Polsce.

During the last decade shift in incidence of pertussis toward the older age groups was observed. Also marked increase in incidence of pertussis in the second half of 1997 and first half of 1998 has occurred in our highly vaccinated population. In lieu of those facts question arises on effectiveness of national vaccination program in respect to immunological adequacy of vaccine used as well as to the vaccinations calendar. Estimations of the values of vaccine efficiency coefficient were calculated for age groups of 2-5, 6-9 and 10-13 years for six month periods in 1997-1998. Sustained good effectiveness of vaccinations was observed in a group 2-5 years of age. In older groups marked decrease of effectiveness was observed during 1997/1998 outbreak of whooping cough. The effectiveness of vaccinations among children of 10-13 years dropped at the outbreak to insignificant levels. Such results indicate good vaccine protection at the age of 2-5 which reflects immunological adequacy of vaccine used in Poland. But this protective effect declines in later years indicating need for additional dose of vaccine for children after five years of age.

[Pertussis in Poland in 1999]. / Krztusiec w 1999 roku.

Following marked increase in number of reported cases of pertussis in 1997/1998, the incidence decreased 1999, but still remained higher than in the years 1993-1996. A general trend toward increase of the fraction of older cases is continued since 1992. The cause of this changing pattern may be decreasing level of antibodies against pertussis following immunizations and lack of a buster dose at the age of 5-7 years. Introduction of such an additional dose of vaccine may increase immunity of those older children who at the present time are susceptible.

[Meningitis and encephalitis in Poland in 1999]. / Zapalenia opon mózgowo-rdzeniowych i zapalenia mózgu w 1999 roku.

2,020 cases of meningitis and 494 of encephalitis were reported in Poland in 1999. Among meningitis 1,024 cases were classified as viral and 996 as bacterial. Etiological factor was determined in 264 (26.5%) cases of bacterial meningitis. Among them Neisseria meningitidis was found in 119 cases, Haemophilus influenzae in 63 cases and Streptococcus pneumoniae in 90 cases. Among types of diagnosed N. meningitidis, as in previous years, type B was strongly predominating. Out of 494 cases of encephalitis 101 cases of tick borne encephalitis were reported in Poland in 1999, most of them from endemic areas of north-eastern part of the country.

Drugs used for cognitive symptoms of Alzheimer's disease.

AD is a devastating disease that is increasing in real numbers as our population ages. The toll on individuals, families, health care, and society will continue to escalate unless more effective treatment approaches are developed. To date, the most effective treatments are those that increase brain ACh levels by retarding the enzymatic breakdown of this neurotransmitter. These agents have proved modestly effective but are far from being the answer to AD. Further, when these drugs are withdrawn, patients rapidly decompensate to the state of disability suffered by those receiving placebo, indicating the deteriorative process continues unabated. The long-term effects on cognition of these drugs also is not known, but most clinicians are not overly optimistic. Other pharmacologic approaches include vitamin E, ginkgo biloba, estrogen, and the nonsteroidal anti-inflammatory drugs. Clinical trials do not robustly support their efficacy at this time, but there are numerous anecdotal reports to promote any or all of these approaches. Newer strategies under study include antiamyloid agents and nootropics (which enhance neuronal metabolic activity). The value of these approaches remains to be confirmed.

Epidemiology of childhood bacterial meningitis in Poland. Incidence of bacterial meningitis with special reference to Haemophilus influenzae type b among children 0-59 months old in the former Kielce and Bydgoszcz districts in Poland in 1998-1999.

Population based surveillance was undertaken to assess the incidence of meningitis caused by Haemophilus influenzae type b in children 0-59 months old in Kielce and Bydgoszcz districts in Poland in 1998 and 1999. The cases were prospectively identified in pediatric and neuroinfection wards of local hospitals where all cases of children with suspected meningitis are referred in both districts. The mean annual incidence of meningitis caused by Haemophilus influenzae type b in children 0-59 months old in Kielce district during the study period was estimated at 3.1 per 100,000 per year (10.3% of cases of bacterial meningitis with confirmed etiology). In Bydgoszcz district, the annual incidence was 9.7 per 100,000 (50% of confirmed cases). These estimations are lower than reported in most Western European countries before the immunization against Hib was introduced. Small numbers of Hib vaccinations reported from both districts do not seem likely to have influenced the data significantly.

[Selective mechanical dilatation of brain arteries: intracranial angioplasty]. / Wybiórcze mechaniczne poszerzenie tetnic mózgowych--wewnatrzczaszkowa angioplastyka.

Intracranial vascular stenosis of haemodynamic significance is underappreciated both clinically and diagnostically. It is thought to be the cause of cerebral ischaemia in 8% of patients. Now it is possible to perform dilatation of the intracranial arterial stenosis by modern intraarterial angioplasty. Two cases are presented of successful dilatation of middle cerebral artery trunk stenosis. Diagnostic problems, follow up and pharmacological treatment as well as technique of intravascular treatment is described.

[Pertussis in 1998]. / Krztusiec w 1998 roku.

In 1998 further global increase in reported cases of pertussis in Poland was observed. The total number of reported cases was 2871 including 854 cases reported in 1998 which occurred in 1997. Most of the cases accumulated in first quarter of the year, with subsequent decrease in the second half of the year, to the level below observed in 1997 in the same seasons. So the most evident increase of the incidence of pertussis was present in the last two quarters of 1997 and first quarter of 1998. Observed temporary increase of pertussis incidence occurred without any significant changes in vaccination coverage and does not seem to be related to changes in vaccine effectiveness. In last two years increased incidence of pertussis was observed in all age groups, but in older ones: 5-9, 10-14 increase in incidence was higher (Table III). Major problem in reporting of pertussis in Poland is small fraction of cases confirmed by culture or by ELISA test, which brings possibility of small specificity of diagnostic procedures used.

[Meningitis and encephalitis in 1998]. / Zapalenia opon mózgowo-rdzeniowych i zapalenia mózgu w 1998 roku.

In 1998--3,024 cases of meningitis and 581 cases of encephalitis were reported. It was 1,436 cases less then in 1997. A significant decrease of enteroviral meningitidis was observed and strains of ECHO30 was not dominant, it was Cox B5. Among bacterial factors the most common was N. meningitidis. 131 sporadic cases of meningitis caused by this bacteria were reported with serotype B dominating (96%). There were 103 cases of bacterial meningitis caused by S. pneumoniae and 101 cases caused by H. influenzae b among those with confirmed diagnosis. There were 208 cases of tick-borne encephalitis, diagnosed mainly in endemic areas of Bialystok and Suwalki voivodeships.

[Tetanus in 1998]. / Tezec w 1998 roku.

In last decade gradual decrease in numbers of reported cases of tetanus was observed. In 1998, 22 cases of tetanus (15 women and 7 men) were reported in Poland. All those cases were among people of age 40 or more. In 54.5% of cases died. Case fatality increased with age, and among people 70 or older all cases were fatal. Among reported cases only 2(10%) people were immunized after injury and 20 (90%) were not. Cases of tetanus were more frequent in rural (14) than in urban (8) regions. The data show effectiveness of vaccination program in younger age groups, but they also show need for promotion of post exposure prophylaxis, especially among older people both in rural and in urban areas. No case of neonatal tetanus was noted in Poland since 1984.