Ischaemic bowel perforation secondary to a gravid uterus in a patient with treated inflammatory bowel disease and an ileoanal pouch: a case report.

The diagnosis of visceral perforation during pregnancy is often delayed and the management complex. A 32-year-old primigravid woman in her second trimester presented with abdominal pain and a pre-existing ileoanal pouch. Initial imaging was negative but later imaging was suggestive of serious pathology. At laparotomy, a caesarean section was performed. Peritonitis was encountered secondary to two discrete perforations in the small bowel separate from her pouch. Histology found an ischaemic perforation secondary to a pressure effect from the gravid uterus. In pregnancy, ileoanal pouches may make the interconnected bowel vulnerable to the pressure effect of the gravid uterus and perforation. Pregnant women with such a surgical history who develop symptoms suggestive of bowel perforation should have rapid imaging and their clinical team should consider early definitive surgical intervention.

Characterization of Ablation Thresholds for 3D-Cultured Patient-Derived Glioma Stem Cells in Response to High-Frequency Irreversible Electroporation.

High-frequency irreversible electroporation (H-FIRE) is a technique that uses pulsed electric fields that have been shown to ablate malignant cells. In order to evaluate the clinical potential of H-FIRE to treat glioblastoma (GBM), a primary brain tumor, we have studied the effects of high-frequency waveforms on therapy-resistant glioma stem-like cell (GSC) populations. We demonstrate that patient-derived GSCs are more susceptible to H-FIRE damage than primary normal astrocytes. This selectivity presents an opportunity for a degree of malignant cell targeting as bulk tumor cells and tumor stem cells are seen to exhibit similar lethal electric field thresholds, significantly lower than that of healthy astrocytes. However, neural stem cell (NSC) populations also exhibit a similar sensitivity to these pulses. This observation may suggest that different considerations be taken when applying these therapies in younger versus older patients, where the importance of preserving NSC populations may impose different restrictions on use. We also demonstrate variability in threshold among the three patient-derived GSC lines studied, suggesting the need for personalized cell-specific characterization in the development of potential clinical procedures. Future work may provide further useful insights regarding this patient-dependent variability observed that could inform targeted and personalized treatment.

Evolving artificial neural networks for screening features from mammograms.

Disagreement or inconsistencies in mammographic interpretation motivates utilizing computerized pattern recognition algorithms to aid the assessment of radiographic features. We have studied the potential for using artificial neural networks (ANNs) to analyze interpreted radiographic features from film screen mammograms. Attention was given to 216 cases (mammogram series) that presented suspicious characteristics. The domain expert (Wasson) quantified up to 12 radiographic features for each case based on guidelines from previous literature. Patient age was also included. The existence or absence of malignancy was confirmed in each case via open surgical biopsy (111 malignant, 105 benign). ANNs of various complexity were trained via evolutionary programming to indicate whether or not a malignancy was present given a vector of scored input features in a statistical cross validation procedure. For suspicious masses, the best evolved ANNs generated a mean area under the receiver operating characteristic curve (AZ) of 0.9196 +/- 0.0040 (1 S.E.), with a mean specificity of 0.6269 +/- 0.0272 at 0.95 sensitivity. Results when microcalcifications were included were not quite as good (AZ = 0.8464), however, ANNs with only two hidden nodes performed as well as more complex ANNs and better than ANNs with only one hidden node. The performance of the evolved ANNs was comparable to prior literature, but with an order of magnitude less complexity. The success of small ANNs in diagnosing breast cancer offers the promise that suitable explanations for the ANN's behavior can be induced, leading to a greater acceptance by physicians.

Linear and neural models for classifying breast masses.

Computational methods can be used to provide an initial screening or a second opinion in medical settings and may improve the sensitivity and specificity of diagnoses. In the current study, linear discriminant models and artificial neural networks are trained to detect breast cancer in suspicious masses using radiographic features and patient age. Results on 139 suspicious breast masses (79 malignant, 60 benign, biopsy proven) indicate that a significant probability of detecting malignancies can be achieved at the risk of a small percentage of false positives. Receiver operating characteristic (ROC) analysis favors the use of linear models, however, a new measure related to the area under the ROC curve (AZ) suggests a possible benefit from hybridizing linear and nonlinear classifiers.

A step toward computer-assisted mammography using evolutionary programming and neural networks.

Artificial intelligence techniques can be used to provide a second opinion in medical settings. This may improve the sensitivity and specificity of diagnoses, as well as the cost effectiveness of the physician's effort. In the current study, evolutionary programming is used to train artificial neural networks to detect breast cancer using radiographic features and patient age. Results from 112 suspicious breast masses (63 malignant, 49 benign, biopsy proven) indicate that a significant probability of detecting malignancies can be achieved using simple neural architectures at the risk of a small percentage of false positives.

Evolving neural networks for detecting breast cancer.

Artificial neural networks are applied to the problem of detecting breast cancer from histologic data. Evolutionary programming is used to train the networks. This stochastic optimization method reduces the chance of becoming trapped in locally optimal weight sets. Preliminary results indicate that very parsimonious neural nets can outperform other methods reported in the literature on the same data. The results are statistically significant.

Adolescent health and social problems. A method for detection and early management. The Dartmouth Primary Care Cooperative Information Project (COOP).

OBJECTIVE: To develop and test a method for identification and early management of the health and social problems of adolescents, many of which go undetected and untreated. METHODS: Picture-and-word charts for the measurement of health and social problems formed the core of a brief, self-teaching lesson. Other sections of the lesson were designed to help teenagers interpret, invent solutions for, and communicate concerns about these problems. We examined the impact of the lesson on teenagers' understanding of themselves, their feelings, and their actions. Two hundred ninety-one adolescents served as subjects for this research. RESULTS: Less than 5% of the respondents found the chart-based lesson difficult or bothersome in the way it probed personal topics. Ninety percent reported that the lesson would have some positive impact on their actions or feelings. Three to six weeks after completing the lesson, their opinion of its impact remained high, and 36% of the students reported that they had shown it to others outside the school. CONCLUSION: A chart-based lesson is well accepted by adolescents and can be used to overcome obstacles for the detection and early management of adolescents' health and social problems.

Change in pH during setting of polyelectrolyte dental cements.

The change in pH during setting has been studied for five different glass polyalkenoate (ionomer) cements and for two different zinc polycarboxylate cements using a flat-headed combination electrode on both the fresh cement and on a slurry of the set cement. The results show that the pH of the glass ionomers was slightly lower in the early stages of setting than was the pH of the zinc polycarboxylates and also that the pH of glass ionomers rises more slowly. For anhydrous cements (i.e. those formulated from dried polymer) pH was found to rise quicker than for hydrous cements (i.e. those prepared from aqueous solutions of polymer). Previous workers have assumed that anhydrous cements undergo slower rises in pH than hydrous ones. Our results clearly refute this assumption, and also suggest that the reported pulpal irritation associated with the use of anhydrous glass ionomers may be due to something other than low pH.

New aspects of the setting of glass-ionomer cements.

For many years, glass-ionomer cements have been described as setting by the formation of a poly(acrylate) matrix. Recent research has suggested that a second reaction may be involved, namely, the formation of a silica matrix. So that this hypothesis could be tested, non-polymer cements, based on an ionomer glass plus acetic acid, were prepared and stored for up to six months. They were insoluble in water, and their compressive strength was found to increase rapidly over the period of storage. By contrast, the product of the reaction between ZnO and acetic acid was soluble in water. These results support the idea that there is a secondary setting reaction in glass ionomers and suggest that it is responsible for the increase in strength observed.

Reinforced glass-ionomer cements--a review of properties and clinical use.

In recent years, two new metal-reinforced Glass-ionomers have been introduced. The aim has been to develop a cement which can be used successfully as a replacement for amalgam. This paper reviews the published literature on the mechanical properties and clinical use of both the cermet and so-called 'Miracle Mix' cements. The published results do not suggest an improvement in strength or adhesion to tooth material; wear resistance is improved, however. One problem encountered in reviewing this literature is the wide variation in test methodology and hence results. In clinical use, the metal-reinforced cement has been successful in Class I and II restorations, particularly using the tunnel technique, and has potential for use in a number of other applications.

The biocompatibility of glass-poly(alkenoate) (Glass-Ionomer) cements: a review.

The literature describing the biocompatibility of glass-poly(alkenoate) ('Glass-Ionomer') cements has been reviewed. This literature shows that these materials have generally good biocompatibility for both dental and orthopaedic use, this latter observation being very recent. There have, though, been a few reports showing that in certain circumstances these materials may cause pulpal irritation and the reasons for these particular findings are considered. Following discussion of the biocompatibility of Glass-Ionomer cements, consideration is given to the likely underlying causes of this feature. Three factors are identified as contributing to the biocompatibility of these cements. They are: (i) minimal exotherm on setting; (ii) rapid neutralization following mixing; and (iii) slow release of ions which are generally biologically beneficial or, at least, benign. This last point is considered in some detail. Previous studies of leaching of ions from Glass-Ionomer cements have shown that only inorganic species are released. The biological effects of each of these inorganic ions are described and their influence on biocompatibility discussed.

Glass-ionomer cements in orthopaedic surgery: design of laboratory tests.

Recently, interest has been shown in the use of Glass-ionomer cement as a bone cement in orthopaedic surgery. This paper discusses the determination of working time, setting time and compressive strength for an experimental Glass-ionomer [GI] and the existing poly(methyl methacrylate) [PMMA] cement. Conventional test methods and some novel techniques are explored. Suggestions are made for new techniques which will allow the comparison of different types of cement. The effect of different storage media on cement stability has shown that both cements show a degree of instability dependent on the medium used. The properties reported for the GI cement suggest that it has the potential to be a new bone cement.