Membership function modification of fuzzy logic controllers with histogram equalization

In most fuzzy logic controllers (FLCs), initial membership functions (MFs) are normally laid evenly all across the universes of discourse (UD) that represent fuzzy control inputs. However, for evenly distributed MFs, there exists a potential problem that may adversely affect the control performance; that is, if the actual inputs are not equally distributed, but instead concentrate within a certain interval that is only part of the entire input area, this will result in two negative effects. On one hand, the MFs staying in the dense-input area will not be sufficient to react precisely to the inputs, because these inputs are too close to each other compared to the MFs in this area. The same fuzzy control output could be triggered for several different inputs. On the other hand, some of the MFs assigned for the sparse-input area are "wasted". In this paper we argue that, if we arrange the placement of these MFs according to a statistical study of feedback errors in a closed-loop system, we can expect a better control performance. To this end, we introduce a new mechanism to modify the evenly distributed MFs with the help of a technique termed histogram equalization. The histogram of the errors is actually the spatial distribution of real-time errors of the control system. To illustrate the proposed MF modification approach, a computer simulation of a simple system that has a known mathematical model is first analyzed, leading to our understanding of how this histogram-based modification mechanism functions. We then apply this method to an experimental laser tracking system to demonstrate that in real-world applications, a better control performance can he obtained by using this proposed technique.

Microtia: ear reconstruction using tissue expander and autogenous costal cartilage

Ear reconstruction is one of the most challenging surgeries faced by the reconstructive surgeon. Currently, the use of autogenous costal cartilage is still best practice for microtia reconstruction. However, the relative deficiency of thin skin for coverage of the cartilage framework remains a limiting factor. Since 1994, we have used tissue expander in the mastoid area and innovated a technique to fabricate cartilage framework. All these innovations may solve the deficiency of the skin and improve cartilaginous framework definition. In conclusion, tissue expander offers a non-hairbearing, thin, well-vascularised skin to envelope an erect, contour-accentuated framework. Most patients with microtia are satisfied with their ear reconstruction.

Heme oxygenase-1 protects brain from acute excitotoxicity

Heme oxygenase is a rate-limiting enzyme that degrades heme, a pro-oxidant, into carbon monoxide, iron, and bilirubin. Heme oxygenase has two active isoforms: heme oxygenase-1 and heme oxygenase-2. Heme oxygenase-1 can be induced by various insults. Several investigators have postulated that it has cytoprotective activities, although its role in the nervous system is not fully understood, especially considering that normally heme oxygenase-2 accounts for the vast majority of heme oxygenase activity in the brain. Here, the basal effect of heme oxygenase-1 was investigated in acute glutamatergic excitotoxicity to test the hypothesis that N-methyl-D-aspartate-induced acute toxicity in brain is attenuated by heme oxygenase-1. N-methyl-D-aspartate was unilaterally injected into the striatum of wildtype and heme oxygenase-1 knockout mice. After 48 h, brains were harvested, sectioned, and stained with Cresyl Violet to measure the lesion size. Lesion volume was significantly (P<0.05) greater in brains of heme oxygenase-1 knockout mice (15.2+/-3.1 mm(3); n=10) than in those of wildtype mice (6.2+/-1.5 mm(3); n=11). In addition, Western blot analysis indicated no detectable differences between wildtype and heme oxygenase-1 knockout mouse brains in the levels of the glutamate or N-methyl-D-aspartate receptors studied. To test whether heme oxygenase-1 could specifically protect neurons, mouse primary neuronal cell cultures of wildtype and heme oxygenase-1 knockout mice were treated with or without N-methyl-D-aspartate. Cell viability of the heme oxygenase-1 knockout neurons was significantly less than that of wildtype neurons at each of the N-methyl-D-aspartate concentrations tested (12.8+/-1.3%, 16.0+/-1.4%, and 18.4+/-1.8% at 30, 100, and 300 microM N-methyl-D-aspartate, respectively). These results indicate that heme oxygenase-1 provides neuroprotection against acute excitotoxicity and suggest that potential intervention that can increase heme oxygenase-1 activity within the brain should be considered as a therapeutic target in acute and potentially chronic neurological disorders.

Detection of mutA genes in transmitted strains and nontransmitted strains of mutans streptococci

Our aim was to determine whether an isolate carrying one of the mutA genes was related to its ability to be transmitted from mother to her child. First, 200 mutans streptococci isolates were genotyped by arbitrarily primed polymerase chain reaction (AP-PCR) to demonstrate transmission between 20 mother-child pairs and to detect the transmitted and nontransmitted strains. Then the mutacin structural genes mutA encoding mutacin types I, II, and III were screened by PCR. The results showed that all strains found to carry the mutAI gene were nontransmitted strains; PCR screening primers mutAII and mutAIII did not yield amplicons in any of the strains tested. Our data suggest that an isolate carrying the mutAI gene is related to reduced transmission. The low frequency of detection of mutAII, and mutAIII suggests that there is a high heterogeneity in the genetic determinants needed for the production of mutacin-like substances.

Positron emission tomography imaging in evaluation of cancer patients

Positron emission tomography (PET) is a diagnostic imaging technique that has progressed rapidly from being a research technique in laboratories to a routine clinical imaging modality. The most widely used radiotracer in PET is Fluorine18-fluorodeoxyglucose (F18-FDG), which is an analogue of glucose. The FDG uptake in cells is directly proportional to glucose metabolism of cells. Since glucose metabolism is increased many fold in malignant tumors PET has a high sensitivity and a high negative predictive value. PET with FDG is now the standard of care in initial staging, monitoring the response to the therapy, and management of lung cancer, colonic cancer, lymphoma, melanoma, esophageal cancer, head and neck cancer and breast cancer. Other indications of PET like bone tumor, ovarian cancer and cancer of unknown primary (CUP) has also been discussed in brief. The aim of this review article is to review the clinical applications of PET in various malignancies and only limited number of important studies will be discussed for this effort.

Applications of fluorodeoxyglucose positron emission tomography in the diagnosis of infection

The purpose of this study was to assess the accuracy of fluorodeoxyglucose positron emission tomography (FDG PET) in diagnosing infection in a large population of patients and in a variety of clinical circumstances where the performance of conventional imaging modalities has been questioned. We retrospectively analysed 167 FDG PET scans obtained to evaluate 175 anatomical sites for the presence of infection. The major indications for the scans were (1) complicated orthopaedic hardware (n=97), (2) chronic osteomyelitis (n=56), and (3) other (n=14: six fever of unknown origin, three vascular grafts, and five soft tissue). We assessed the overall diagnostic accuracy of FDG PET for each of these indications. In addition, we further analysed this modality's effectiveness by grouping the scans into specific clinical situations. A final diagnosis was made on the basis of surgical pathology and clinical follow-up for a minimum of 6 months. The overall accuracy of FDG PET in evaluating orthopaedic hardware was 96.2% for hip prosthesis, 81% for knee prosthesis, and 100% in 15 patients with other orthopaedic devices. Among the patients in our sample suspected of having chronic osteomyelitis, the accuracy was 91.2%. FDG PET was inaccurate in three cases of fever of unknown origin and accurate in all vascular graft and soft tissue infections. In 49 patients with a clinically apparent soft-tissue infection, FDG PET was able to detect or exclude underlying osteomyelitis with an accuracy of 92.3%. Among the 23 patients who had recent orthopaedic procedures, FDG PET imaging was accurate in 87% of cases. It is concluded that FDG PET is a highly effective imaging modality in the assessment of patients with suspected infection.

Sentinel lymph node biopsy in the management of breast cancer

Sentinel node localization is the second most important development in this century after conservative lumpectomy for the treatment of early breast cancer. The sentinel node mapping is a new multidisciplinary approach for staging of axilla in an accurate and less morbid way as compared to axillary node dissection. Sentinel lymph node biopsy in patients with breast cancer has been adopted rapidly into clinical practice. The accuracy of sentinel lymph node biopsy is more than 95%, when performed meticulously (by an experienced multidisciplinary team) with proper patient selection. Sentinel lymph node biopsy is most widely used for both palpable and non-palpable T1 and T2 tumors. Recent studies show application of sentinel lymph node technique in patients with locally advanced breast cancer and after neoadjuvant chemotherapy. Therefore, sentinel lymph node biopsy technique has application in developing countries and other countries where screening for breast cancer is not common and most patients present relatively in advanced stage of the disease. Several aspects of the sentinel lymph node biopsy including technique, case selection, pathologic analysis and accuracy with supportive important studies published in the literature will be discussed in this review.

Effect of fluoride pretreatment on the solubility of synthetic carbonated apatite

The purpose of this research was to address the following question: How is the solubility of fluoride-pretreated carbonated apatite (CAP) in aqueous acidic media related to the equilibrium solution fluoride and/or the CAP adsorbed fluoride levels? A CAP sample prepared by a precipitation method at 70 degrees C containing approximately 6% carbonate was fluoride-treated (F adsorption from neutral aqueous solutions) to yield a approximately 1000 ppm F CAP and a approximately 3300 ppm F CAP. Metastable equilibrium solubility distributions were determined in acetate buffers at pH 5.0. Solution fluoride, calcium, phosphate, and pH were determined from the equilibrated solutions. The equilibrium solution fluoride levels were extremely low, e.g., as low as approximately 0.10 ppb to approximately 0.30 ppb at 50% dissolved for the two CAP preparations. The approximately 3300 ppm F CAP yielded a lower solubility than the approximately 1000 ppm F CAP (shift in the mean pKHAP value of 1.5-2 units). This can be attributed to the lower solution F(-) for the sample containing approximately 1000 ppm fluoride compared with the approximately 3300 ppm fluoride-containing CAP. These important findings suggest that a fluoride treatment simply may provide an adsorption fluoride depot for subsequent release, providing a solution fluoride effect upon the CAP solubility and not necessarily any intrinsic alteration of the mineral solubility.

The importance of the location of fluorodeoxyglucose uptake in periprosthetic infection in painful hip prostheses

Ten per cent of patients with hip replacement will eventually complain of significant pain after surgery, often requiring a revision arthroplasty. The majority of these patients experience aseptic loosening rather than infection. Despite significant advances made in diagnostic imaging, distinguishing infection from aseptic loosening remains a significant challenge. Imaging using fluorodeoxyglucose (FDG) positron emission tomography (PET) has been reported to have excellent sensitivity in detecting infections associated with hip prostheses. However, in some studies, a high rate of false positive results has been reported, especially when increased tracer uptake adjacent to the prosthesis (which is not surrounded by bone) is used as the sole criterion for diagnosing infection. The objective of this investigation was to determine the optimal criteria for diagnosing periprosthetic infection, thereby avoiding false positive results in this setting. A total of 41 total hip arthroplasties from 32 patients and for whom complete clinical follow-up was available were included in this analysis. The location and intensity of FDG uptake were determined for each scan. Final diagnosis was made by microbiology, histopathology, surgical findings and clinical follow-up. Patients who did not undergo surgery were followed up to at least 9 months. Twelve patients were proven eventually to have periprosthetic infection. Images from 11 of these patients displayed increased tracer uptake along the interface between bone and prosthesis. The intensity of the increased tracer uptake varied from mild to moderate, with standardized uptake values less than 2. In contrast, images from uninfected, loose hip prostheses revealed very intense uptake around the head or neck of the prosthesis with standardized uptake values as high as 7. It is concluded that the intensity of increased FDG uptake is less important than the location of increased FDG uptake when FDG PET is used to diagnose periprosthetic infection in patients with hip arthroplasty. Using increased uptake as the sole criterion for diagnosing infection will result in false positive results in this setting.

[Clinical significance of Q-Tc dispersion after exercise in aged patients with old myocardial infarction]

OBJECTIVE

This study was aimed to evaluate clinical significance of Q-Tc dispersion after exercise in aged patients with old myocardial infarction.

METHOD

Sixty-four aged patients with old myocardial infarction(infarction group) were examined by treadmill exercise, dynamic electrocardiography, echocardiography, and were followed up for average of 24.12 +/- 7.7 months. 30 healthy aged persons were served as control group.

RESULTS

Compared with that (40.21 +/- 15.21 ms) before exercise, Q-Tc dispersion (59.37 +/- 20.17 ms) was increased significantly after exercise in infarction group(P < 0.01). But no significant difference was found in Q-Tc dispersion of control group before and after exercise(34.70 +/- 12.29 ms vs 38.91 +/- 13.62 ms P > 0.05). In infarction group, occurrence of abnormal contraction of left ventricular wall, aneurysms, NYHA III class and > III class of Lown's ventricular arrhythmia classification was significantly higher in Q-Tcd > 50 ms patients than that in Q-Tcd < 50 ms ones(P < 0.05). It was found that 5 patients died of cardiac sudden death in Q-Tcd > 50 ms patients and no one died of cardiac sudden death in Q-Tcd < 50 ms ones.

CONCLUSION

The Q-Tc dispersion after exercise is an important index to predict ventricular arrhythmia and cardiac death in the patients with old myocardial infarction.

[Does semi-quantitative analysis of FDG-PET have any additional value in the diagnosis of mesial temporal sclerosis?]

The aim of this study was to compare qualitative visual analysis with semi-quantitative analysis in the diagnosis of mesial temporal sclerosis (MTS) using FDG-PET.

METHODS

This study included 21 patients with histopathological confirmation of MTS. FDG-PET visual analysis data were based on clinical reports generated soon after the completion of the scan. FDG-PET images were semi-quantitatively analyzed using regions of interest (ROIs) in 19 slices perpendicular to the longest axis of the temporal lobe. These ROIs divided each temporal lobe into three regions (lateral, inferior and medial). An asymmetry index was calculated for each region.

RESULTS

The visual analysis of the FDG-PET studies demonstrated asymmetric hypometabolism in all patients. All but 1 patient underwent standard lobectomy of the same side described as hypometabolic by the PET report. Using an asymmetry index equal or greater than 9% in at least one of the regions as a threshold, the FDG-PET semi-quantitative analysis showed significant asymmetry in 18 patients. These also matched the side of lobectomy and were confirmed as sclerotic in all but one patient (same patient as above).

CONCLUSION

The semi-quantitative analysis did not provide additional information over visual interpretation in this series of patients.