Global survival trends for brain tumors, by histology: analysis of individual records for 556,237 adults diagnosed in 59 countries during 2000-2014 (CONCORD-3)

BACKGROUND

Survival is a key metric of the effectiveness of a health system in managing cancer. We set out to provide a comprehensive examination of worldwide variation and trends in survival from brain tumors in adults, by histology.

METHODS

We analyzed individual data for adults (15-99 years) diagnosed with a brain tumor (ICD-O-3 topography code C71) during 2000-2014, regardless of tumor behavior. Data underwent a 3-phase quality control as part of CONCORD-3. We estimated net survival for 11 histology groups, using the unbiased nonparametric Pohar Perme estimator.

RESULTS

The study included 556,237 adults. In 2010-2014, the global range in age-standardized 5-year net survival for the most common sub-types was broad: in the range 20%-38% for diffuse and anaplastic astrocytoma, from 4% to 17% for glioblastoma, and between 32% and 69% for oligodendroglioma. For patients with glioblastoma, the largest gains in survival occurred between 2000-2004 and 2005-2009. These improvements were more noticeable among adults diagnosed aged 40-70 years than among younger adults.

CONCLUSIONS

To the best of our knowledge, this study provides the largest account to date of global trends in population-based survival for brain tumors by histology in adults. We have highlighted remarkable gains in 5-year survival from glioblastoma since 2005, providing large-scale empirical evidence on the uptake of chemoradiation at population level. Worldwide, survival improvements have been extensive, but some countries still lag behind. Our findings may help clinicians involved in national and international tumor pathway boards to promote initiatives aimed at more extensive implementation of clinical guidelines.

Multi-layer PDMS films having antifouling property for biomedical applications

Poly(dimethylsiloxane) (PDMS) elastomer is now a well-known material for packaging implantable biomedical micro-devices owing to unique bulk properties such as biocompatibility, low toxicity, excellent rheological properties, good flexibility, and mechanical stability. Despite the desirable bulk characteristics, PDMS is generally regarded as a high-flux material for oxygen and water vapor to penetrate compared with other polymeric barrier materials, which is related to the defect-induced penetration through the packaging coating prepared by the traditional deposition techniques. Besides, its hydrophobic nature causes serious fouling problems and limits the practical application of PDMS-based devices. In this work, the performance of silicone thin films as a packaging layer was improved by the fabrication of the roller-casted multiple thin layers to minimize a defect-induced failure. To confer hydrophilicity and cell fouling resistance, high-density and well-defined poly(oligo(ethylene glycol) methacrylate) (POEGMA) brushes were tethered via the surface-initiated atom transfer radical polymerization (SI-ATRP) technique on the roller-casted multiple thin PDMS layers. The characteristics of fabricated substrates were determined by static water contact angle measurement, X-ray photoelectron spectroscopy, and attenuated total reflection-Fourier transform infrared spectroscopy. In vitro cell behavior of POEGMA-grafted PDMS substrates was evaluated to examine cell-fouling resistance.

Histological evaluation of inferior alveolar nerve injury after osteotomy of mandibular buccal cortex using piezoelectric versus conventional rotary devices: a split-mouth randomised study in rabbits

Up until now, only a limited number of evidence-based studies with different results has evaluated traumatic nerve injury after maxillofacial surgery using piezoelectric devices versus rotary instruments. The present experiment was performed to evaluate damage to the inferior alveolar nerve (IAN), histologically, after osteotomy of the buccal cortex of the mandible using piezoelectric devices versus surgical handpieces. Forty rabbits underwent bilateral osteotomy of the mandibular buccal cortex. For the osteotomy of one side, piezoelectric devices were used, and for the other, conventional rotary handpieces. After cleavage of the osteotomised cortical bone segments, the exposed part of the IAN was excised and examined histologically for nerve injury. IAN damage was scored histologically from Grade 0 (no nerve damage) to Grade 4 (complete nerve transection). It was found that 25% and 17.5% of nerves had Grade 0; 17.5% and 10% had Grade 1; 25% and 20% had Grade 2; 17.5% and 27.5% had Grade 3; and 15% and 25% had Grade 4 injury in piezosurgery and rotary groups, respectively. Statistical analyses revealed no significant difference between groups in damage to the IAN. The present study showed that piezosurgery devices, similar to conventional rotary instruments, have the potential to cause severe nerve damage during surgery and should therefore be used with care.

Spatio-temporal analysis of error-related brain activity in active and passive brain-computer interfaces

Electroencephalography (EEG)-based brain–computer interface (BCI) systems infer brain signals recorded via EEG without using common neuromuscular pathways. User brain response to BCI error is a contributor to non-stationarity of the EEG signal and poses challenges in developing reliable active BCI control. Many passive BCI implementations, on the other hand, have the detection of error-related brain activity as their primary goal. Therefore, reliable detection of this signal is crucial in both active and passive BCIs. In this work, we propose CREST: a novel covariance-based method that uses Riemannian and Euclidean geometry and combines spatial and temporal aspects of the feedback-related brain activity in response to BCI error. We evaluate our proposed method with two datasets: an active BCI for 1-D cursor control using motor imagery and a passive BCI for 2-D cursor control. We show significant improvement across participants in both datasets compared to existing methods.

Abstract P1-08-32: Treatment delivery waiting times for stage I-III breast cancer patients in Switzerland : A pooled analysis of 7 cancer registries over the 2003-2008 period

Background: To examine time intervals between needle/core biopsy, breast cancer diagnosis, surgery and radiotherapy (RT) as quality metrics in the management of stage I-III breast cancer in a representative Swiss population sample.

Methods: Based on seven regional cancer registries covering 45% of the Swiss population, we identified 2628 women which underwent surgery for stage I-III breast cancer without receiving (neo)-adjuvant chemotherapy between January 1, 2003 and December 31, 2005.

Four different time intervals were defined: a) time between needle/core biopsy and diagnosis of breast cancer, b) time between diagnosis of breast cancer and surgery, c) time between needle/core biopsy and surgery, d) time between surgery and adjuvant RT.

These four time intervals were analyzed according to age, nationality, health insurance status, public vs. private hospitals and geography. We also investigated whether case discussion at tumor board delayed patient management.

A one-way analysis of variance (ANOVA) and multiple comparison tests were used to assess differences between groups. All tests were performed using STATA v.15.

Results: 2628 women were identified, median age was 67 years (IQR: 58-77). Breast-conserving surgery was performed in 1899 cases (72.3%), mastectomy in 539 cases (20.5%), unspecified surgery /missing data in 190 cases (7.2%). Adjuvant RT was delivered in 1546/2628 patients (58.8 %).

Time interval between biopsy and surgery was age-dependent, ranging from 22 days (95% CI: 19.6 - 25.2) for women < 60 years to 39 days (95% CI: 27.0-50.3) for women 80+ years old (p<0.001). After biopsy, women waited on average 19 days until surgery in private clinics (95% CI: 16.4-21.6) and 30 days in public hospitals (95% CI: 26.6-33.3) (p<0.001). Women with private insurance were operated 24 days after biopsy (95% CI: 17.0-31.1), compared with 30 days (95% CI: 27.1-33.2) (p<0.01)for women with basic state insurance. After biopsy, time interval for foreign nationals was significantly longer than for Swiss citizen (30 vs 24 days, p<0.01). Tumor board presentation postponed surgery by 10 days (31 vs 22 days, p<0.01).

Time between surgery and RT did not correlate with age (p=0.83); the interval was 33% longer in tertiary teaching hospitals than in private clinics (61 vs. 46 days, p<0.001), and 8 days longer for patients with private insurance than for those without (61 vs 53 days, p<0.01). There was a trend for foreign nationals to receive adjuvant RT later than Swiss citizen (58 vs 55 days, p=0.09). RT started later in larger metropolitan areas compared to more rural regions (59 vs 53 days, p<0.01). Presenting patients at a tumor board after surgery had no impact on RT start (p=0.12).

Conclusions: Major differences in treatment waiting times were observed between patients with stage I-III breast cancer. Elderly and foreign patients were at risk for delayed surgery after biopsy. Data from patients with longer timelines need to be analyzed to identify further reasons for delays.

Citation Format: Zwahlen DR, Herrmann C, Mousavi M, Bordoni A, Bouchardy C, Konzelmann I, Staehlin K, Rohrmann S, Oehler C, Zimmermann M. Treatment delivery waiting times for stage I-III breast cancer patients in Switzerland : A pooled analysis of 7 cancer registries over the 2003-2008 period [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-08-32.

[Surgical revision for complications after gamma3-nailing osteosynthesis of proximal humeral fractures : Follow-up series of 1500 patients]

BACKGROUND

The γ‑nailing system is a widespread intramedullary therapeutic option that has been used for intertrochanteric and subtrochanteric fractures since the late 1980s; however, some reports from the 1990s describing femoral shaft fractures questioned the indications for this system in simple fracture types. Due to increasing numbers of patients treated with this system, the complication rate is continuously falling as confirmed by many recent studies.

OBJECTIVE

Between 2008 and 2013 a total of 1500 operations using the γ‑nailing system were performed at this traumatology department. The standard 200 mm nail was used in 1290 cases and the extended system available from 340 to 440 mm in 210 cases. The aim of this study was to record the excellent results using the standard γ‑nailing system and to confirm the indications of the long intramedullary nailing system (Gamma3®) also for use in complex intertrochanteric and subtrochanteric fractures.

MATERIAL AND METHODS

All 1500 patients were retrospectively analyzed. Information on epidemiological data, intraoperative and postoperative complications and patient outcome was retrieved from the digital patient medical history. All available radiographs were assessed by a single traumatologist.

RESULTS

The results showed a low complication rate of 5% for surgical complications, mainly caused by cutting out in 34.66%, followed by hematomas in 21.33% and fractures of the nail in 16%. A comparison of the standard and long nailing systems could be carried out, showing a complication rate of 3.64% for the standard system compared to 13.33% for the long γ‑nail system.

CONCLUSION

The γ‑nailing system is a safe treatment option for trochanteric femoral fractures and failure of the implant is associated with high biomechanical forces in unstable fractures. A low complication rate is linked to a thorough surgical technique under consideration of a correct positioning of the implant.

Monte Carlo Simulation of Electron Beams produced by LIAC Intraoperative Radiation Therapy Accelerator

Background

One of the main problems of dedicated IORT accelerators is to determine dosimetric characteristics of the electron beams. Monte Carlo simulation of IORT accelerator head and produced beam will be useful to improve the accuracy of beam dosimetry.

Materials and Methods

Liac accelerator head was modeled using the BEAMnrcMonte Carlo simulation system. Phase-space files were generated at the bottom of the applicators. These phase-space files were used as an input source in DOSXYZnrc and BEAMDP codes for dose calculation and analysis of the characteristic of the electron beams in all applicators and energies.

Results

The results of Monte Carlo calculations are in very close agreement with the measurements. There is a decrease in the peak of the initial spectrum when electrons come from the end of accelerator wave guide to the end of applicator. By decreasing the applicator diameter, the mean energy of electron beam decreased. Using applicators and increasing their size, X-ray contamination will increase. The percentage of X-ray contamination increases by applicator diameter. This is related to the increase of the mean energy of electron beams.

Conclusion

Application of PMMA collimator leads to, although well below accepted level, the production of bremsstrahlung. The results of this study showed that special design of LIAC head accompanying by PMMA collimator system cause to produce an electron beam with an individual dosimetric characteristic making it a useful tool for intraoperative radiotherapy purposes.

Effects of supplemental conjugated linoleic acids (CLA) on fresh and post-thaw sperm quality of Holstein bulls

This study was designed to investigate the effects of feeding-protected conjugated linoleic acid (CLA) on the semen production and sperm freezability in Holstein bulls. Twelve bulls were randomly assigned to two groups (n = 6 per group). Bulls received the normal diet (control group) or the normal diet top-dressed with 50 g of CLA (treated group) for 10 weeks. The control group received 40 g/day calcium soap of fatty acid. Fresh and post-thaw semen quality was assessed on ejaculates collected at the 0, 4, 6, 8 and 10 week of supplementation. Semen evaluations including sperm concentration, motion characteristics (subjective and computer-assisted), viability (Eosin-Nigrosin), membrane integrity (hypo-osmotic swelling test) and abnormality were conducted. Semen volume, sperm concentration and total sperm output were not affected by dietary treatment (p > .05). The proportion of spermatozoa with abnormal morphology in fresh semen significantly increased (p < .05) in the CLA-fed group compared to control group. Also, in CLA-fed group, the proportion of post-thaw spermatozoa with abnormal morphology at week 10 of trial was significantly higher in CLA than control group (p < .05). Progressive motility tended to be increased in the CLA-fed group, although dietary supplementation did not affect other CASA parameters or viability in fresh and frozen-thawed sperm. In this study, CLA supplementation had little positive effect on fresh or post-thaw sperm quality of Holstein bulls.

Days spent in acute care hospitals at the end of life of cancer patients in four Swiss cantons: a retrospective database study (SAKK 89/09)

Number of days spent in acute hospitals (DAH) at the end of life is regarded as an important care quality indicator for cancer patients. We analysed DAH during 90 days prior to death in patients from four Swiss cantons. Claims data from an insurance provider with about 20% market share and patient record review identified 2086 patients as dying of cancer. We calculated total DAH per patient. Multivariable generalised linear modelling served to evaluate potential explanatory variables. Mean DAH was 26 days. In the multivariable model, using complementary and alternative medicine (DAH = 33.9; +8.8 days compared to non-users) and canton of residence (for patient receiving anti-cancer therapy, Zürich DAH = 22.8 versus Basel DAH = 31.4; for other patients, Valais DAH = 22.7 versus Ticino DAH = 33.7) had the strongest influence. Age at death and days spent in other institutions were additional significant predictors. DAH during the last 90 days of life of cancer patients from four Swiss cantons is high compared to most other countries. Several factors influence DAH. Resulting differences are likely to have financial impact, as DAH is a major cost driver for end-of-life care. Whether they are supply- or demand-driven and whether patients would prefer fewer days in hospital remains to be established.

Survival in patients with primary liver cancer, gallbladder and extrahepatic biliary tract cancer and pancreatic cancer in Europe 1999-2007: Results of EUROCARE-5

BACKGROUND

The EUROCARE study collects and analyses survival data from population-based cancer registries (CRs) in Europe in order to provide data on between-country differences in survival and time trends in survival.

METHODS

This study analyses data on liver cancer, gallbladder and extrahepatic biliary tract cancers ("biliary tract cancers"), and pancreatic cancer diagnosed in 2000-2007 from 88 CRs in 29 countries. Relative survival (RS) was estimated overall, by region, sex, age and period of diagnosis using the complete approach. Time trends in 5-year RS over 1999-2007 were also analysed using the period approach.

RESULTS

The prognosis of the studied cancers was poor. Age-standardised 5-year RS was 12% for liver cancer, 17% for biliary tract cancers and 7% for pancreatic cancer. There were some between-country differences in survival. In general, RS was low in Eastern Europe and high in Central and Southern Europe. For all sites, 5-year RS was similar in men and women and decreased with advancing age. No substantial changes in survival were reported for pancreatic cancer over the period 1999-2007. On average, there was a crude increase in 5-year RS of 3 percentage points between the periods 1999-2001 and 2005-2007 for liver cancer and biliary tract cancers.

CONCLUSIONS

The major changes in imaging techniques over the study period for the diagnosis of the three studied cancers did not result in an improvement in the prognosis of these cancers. In the near future, new innovative treatments might be the best way to improve the prognosis in these cancers.

Wastewater pretreatment of a welding electrode manufacturing plant before nanofiltration

This paper finds out appropriate methods of wastewater pretreatment of a welding electrode manufacturing plant before use of nanofiltration. Based on some preliminary experimentation, it was concluded that the coagulation-flocculation and centrifuge processes in the separation of colloid particles were more effective. At first step, the effect of different concentrations of a mixture of alum (Al2 (SO4)3 x 18H2O) and ferric chloride (FeCl3) on turbidity reduction, clarified wastewater percentage, and the rate of sedimentation were closely studied. The results show that a mixture of 2.5 g/L comprising 25% alum and 75% ferric chloride is an optimum dose and more economic. In the next step, the effect of various RPMs and different time periods on the turbidity reduction by the centrifugal method was studied. The centrifuge experiment results show that the colloidal particles are easily converted to dense granular form. Wastewater turbidity can be reduced up to 98% for 4000 RPM and 30 minutes duration. Time operations more than 30 minutes and above 3000 RPMs did not have a significant effect on the turbidity reduction. Regarding the operation costs and energy consumption, it can be concluded that 30 minutes time operation and 3000 RPM were optimal. As the centrifugal method is free from chemicals and wastewater recovery with this method is high, this method appears to be advantageous.

Effect of Phosphoric Acid Etching of Enamel Margins on the Microleakage of a Simplified All-in-One and a Self-etch Adhesive System

This study evaluates the effect of phosphoric acid etching of enamel margins on the microleakage of a simplified all-in-one and a self-etching adhesive system in comparison to a conventional total-etch system.

Borderline ovarian tumours: clinical analysis of 38 cases

Thirty-eight patients with ovarian tumours of low malignant potential (borderline) were diagnosed and treated in Tehran University Gynecology Oncology Department from 1991 to 2002, and have been reviewed. In this study age, clinical behavior, symptoms, surgical stage, type of tumour, surgery, adjuvant treatment, survival and recurrences were evaluated. A retrospective chart review was performed on these 38 patients who were treated for histopathologically confirmed tumours of low malignant potential between 1991-2002. The mean age was 34.4 years, range (14-83) (SD: 18.33). Post surgical FIGO staging was: Stage I=93.75%, stage III 6.25%. Histologic subtypes were: Serous 76.31% (29 patients), Mucinous 21.05% (8 patients), Mixed types 2.63% (1 patient). Mean pre-operative CA125 value was 114.90 (SD: +/- 90.30). Thirty-three percent of patients had only a simple cyst in ultrasonography. Conservative surgery was performed in 76.32% (29 patients). More radical surgery (TAH + BSO) was performed in 9 patients (23.68%). There were 6 recurrences. Three patients with recurrence and invasive implants received chemotherapy and secondary surgery was performed. Survival rate was 100% at 3 years for all stages and 89% at 5 years. One patient died of recurrent disease at 48 months after initial diagnosis. Our data suggest that LMP tumours are most frequently diagnosed in stage I. Most common histological type was serous, and 5 of the recurrences of (6 patients) were initially diagnosed at stage I, and had been treated with conservative surgery with no adjuvant therapy.

Minimally invasive ilioinguinal approach to the acetabulum

The classic ilioinguinal approach is a gold standard in acetabular surgery. We developed a modification, a minimally invasive method that entails a median lower abdominal approach with extraperitoneal dissection and exposure of the pubic symphysis. The second incision is lateral, next to the iliac crest. This allows an easy, safe and quick exposure of the anterior iliac ring as well as easy access to the posterior column and wall towards the sacroiliac joint. The iliac vessels and nerves are thereby protected, and no preparation of neurovascular structures is required. The technique was applied in 23 clinical cases and compared with the classic ilioinguinal approach in 9 similar cases over the same period.

Abnormal Cambridge low-contrast grating sensitivity results associated with diabetic retinopathy as a potential screening tool

Contrast sensitivity is proposed as a potential screening tool for the early detection of diabetic retinopathy. A cross-sectional study was performed in a tertiary referral university eye centre. A total of 80 diabetes patients were recruited and tests were performed on 154 eyes. Contrast sensitivity was checked using Cambridge low-contrast grating. Abnormal contrast sensitivity was observed in 27.1% of eyes with diabetic retinopathy, compared with 9.0% in unaffected eyes, a statistically significant difference. Cambridge low-contrast grating is a potential screening tool for early detection of diabetic retinopathy by non-ophthalmologists.

Regulation of alpha- and beta-secretase activity by oxysterols: cerebrosterol stimulates processing of APP via the alpha-secretase pathway

The cholesterol 24-hydroxylase encoded by the gene CYP46 is expressed almost exclusively in central nervous system (CNS) neurons and catalyzes the formation of 24S-hydroxycholesterol (24S-OHC) from cholesterol. This conversion corresponds to a major pathway for excretion of excess cholesterol from the brain. There is a significant flux of another oxysterol, 27-hydroxycholesterol (27-OHC) from the circulation into the brain. Polymorphisms within the CYP46A1 gene have been associated with Alzheimer's disease (AD) incidence. In this study, we examined the effects of 24S-OHC and 27-OHC on the alpha- and beta-secretase activity in the human neuroblastoma cell line SH-SY5Y. Furthermore, we examined the effects of the two oxysterols on the levels of extra- and intracellular proteins of secreted APPalpha (sAPPalpha). Our findings suggest that 24S-OHC may exert a unique modulatory effect on APP processing and that this oxysterol increases the alpha-secretase activity as well as the alpha/beta-secretase activity ratio. The possibility is discussed that the ratio between 24S-OHC and 27-OHC is of importance for the generation of amyloid in the brain.

Knowledge, attitudes and sources of information regarding HIV/AIDS in Iranian adolescents

The World Health Organization recently reported an 'alarming trend' of increasing Human Deficiency Virus (HIV) infection in the Islamic Republic of Iran. Adolescents form a particularly important target group for primary prevention. An anonymous questionnaire, derived from standard surveys such as the Safer Choices questionnaire and the 2001 Youth Risk Behavior Survey, was distributed to 1227 Iranian students attending 19 randomly selected high schools in Hashtgerd in 2002. Students reported that television (84%) and school teachers (66%) were the best sources of HIV/AIDS information, while parents (27%) and school books (15%) were least informative. Most students knew that heterosexual intercourse (90%) and shared intravenous needles (94%) can cause HIV infection; however, salient misconceptions were revealed. Only 53% were aware that condoms protect against infection through sexual intercourse. More effective school-based HIV/AIDS education is needed in Iran.

Optimization of solid-phase microextraction of volatile phenols in water by a polyaniline-coated Pt-fiber using experimental design

Solid-phase microextraction (SPME) coupled to gas chromatography (GC) was applied to the extraction of phenol and some of its volatile derivatives in water samples. The SPME fiber consisted of a thin layer of polyaniline, which was electrochemically coated on a fine Pt wire. The stability of the coating was such that it could be used at temperatures as high as 325 degrees C, without any deterioration. The effects of various parameters affecting the extraction efficiency were studied, simultaneously. From these, optimization of the extraction temperature, extraction time, coating thickness, sample pH, salt concentration and desorption time was carried out by means of a (2(6-2)) fractional factorial design. It was found that the effects and interactions of five out of six factors were significant. However, the coating thickness showed a large main effect but an insignificant interaction effect, so it was kept constant. Also, the effect of desorption time was insignificant if sufficient time was allowed for desorption to take place. Therefore, a central composite design (CCD) with four remaining factors, i.e., sample pH, salt concentration, extraction time and sample temperature was performed and a response surface equation was derived. The statistical parameters of the derived model were r=0.97 and F=25.3. The optimum conditions were obtained using a grid method. Using the optimum conditions, the method was analytically evaluated. The detection limit, relative standard deviation, linear range and recovery were 1.3-12.8 ng mL(-1), 2.2-5.3%, 0.01-5.0 microg mL(-1), and 88-103%, respectively. The results showed the suitability of polyaniline-coated fiber in analyzing volatile phenolic compounds in water samples.

A new simplified technique for producing platelet-rich plasma: a short technical note

A possible strategy to promote the wound-healing cascade in both soft and hard tissues is the preparation of an autologous platelet-rich plasma (PRP) to encourage the release of growth factors from activated platelets. In this process, PRP combines the advantage of an autologous fibrin clot that will aid in hemostasis as well as provide growth factors in high concentrations to the site of a tissue defect. The PRP preparation can be used as a biological enhancer in the healing of fractures and lumbar fusions. The local application of growth factors seems to promote initiation and early maturation of bone formation. Autologous bone or bone substitutes can be added to this mixture to increase the volume of grafting material. A simplified technique utilizing a commercially available separation system (GPS-Gravitational Platelet Separation System) is described. This system provides a less costly alternative to other previously described augmentation techniques and also presents a patient-friendly and operator-safe alternative. Further experimental studies of the actual concentrations of the growth factors in the PRP samples are necessary in order to validate the platelet concentration and growth-factor activation by laboratory evidence. In further prospective clinical trials, the safety and efficacy of PRP, in combination with autologous bone or bone graft substitutes, must be evaluated.

Reduced levels of Abeta 40 and Abeta 42 in brains of smoking controls and Alzheimer's patients

The effects of nicotine on levels of Abeta 40 and Abeta 42 and nicotinic receptor binding sites were studied in brains from nonsmoking and smoking patients with Alzheimer's disease (AD) and aged-matched controls. The levels of soluble and insoluble Abeta 40 and Abeta 42 in frontal cortex and Abeta 40 in temporal cortex and hippocampus were significantly decreased in smoking AD patients compared to nonsmokers with AD. In smoking controls the levels of soluble and insoluble Abeta 40 and Abeta 42 in the frontal and temporal cortex were significantly lower than in nonsmoking controls. The binding of [(3)H]cytisine in temporal cortex was significantly increased in smokers with AD compared to nonsmokers with AD. In smoking controls [(3)H]cytisine and [(3)H]epibatidine binding were significantly increased from 1.5- to 2-fold compared to nonsmoking controls whereas binding sites for [(125)I]alpha-bungarotoxin was less up-regulated. These results indicate that selective nicotinic receptor agonists may be a novel protective therapy in AD by reducing Abeta levels as well as the loss of nicotinic receptors in AD brain.

Prediction of relative response factors of electron-capture detection for some polychlorinated biphenyls using chemometrics

The relative response factor (RRF) of an electron-capture detection (ECD) system is predicted for a set of 118 polychlorinated biphenyls (PCBs). Due to the wide range of relative retention times of PCB congeners, the RRFs of these compounds were calculated based on two different internal standards. Therefore, the compounds were divided into two molecular subsets. As a first step, multiple linear regression (MLR) was employed to find informative descriptors that can predict the RRFs of these compounds. Two descriptors of molecular ion ionization potential (MIIP) and ionization potential of the molecule (IP) that are related to affinity of the compounds for the electrons show the highest mean effects in subsets 1 and 2. respectively. The descriptors appearing in the MLR models were considered as inputs for developing the back-propagation artificial neural networks (BP-ANN). Two networks with the architectures of 5-5-1 and 7-6-1 were generated for the prediction of RRFs of molecules of subsets 1 and 2, respectively. Comparison of the results indicates the superiority of neural networks over that of the MLR method indicating the nonlinear behaviors of the ECD system. Inspection of the models reveals that the surface of the molecules play different roles in response factors of two subsets due to rotation of one phenyl group with respect to the other for the subset consisting of larger number of chlorine atoms.