神经网络在发动机试验数据拟合中的应用

本文将神经网络应用于发动机试验数据的拟合，为改善神经网络性能引入了函数连接。研究表明：神经网络能够避免数据的分析和建模工作，能够识别有噪声的输入模式，数据拟合精度高，可减少分析人员的介入。     

Rapid detection of a Schistosoma mansoni circulating antigen excreted in urine of infected individuals by using a monoclonal antibody

Schistosoma circulating antigens were used to indicate the infection intensity and to assess cure. An immunoglobulin G2a (IgG2a) mouse monoclonal antibody was used in a fast dot-enzyme-linked immunosorbent assay (ELISA; FDA) for rapid and simple diagnosis of schistosomiasis in the field. Seven hundred Egyptians were parasitologically examined for Schistosoma mansoni and other parasitic infections. A rectal biopsy was done as a "gold standard" for individuals showing no S. mansoni eggs in their feces. Egg counts were obtained by the Kato smear method for only 100 of 152 individuals with eggs in their feces. Specific anti-schistosome IgG antibodies were evaluated in sera by ELISA. Urine samples from the 700 individuals were tested by FDA for detection of the circulating antigen. The assay showed a sensitivity of 93% among 433 infected individuals and a specificity of 89% among 267 noninfected individuals. FDA showed the highest efficiency of antigen detection (91%) compared with the efficiency of antibody detection by ELISA (75%) and stool analysis (60%). In addition, FDA detected infected patients with 20 eggs/g of feces. Also, the sensitivity of FDA ranged from 90 to 94% among samples from patients with different clinical stages of schistosomiasis. All the assay steps can be completed within 30 min at room temperature for 96 urine samples. The monoclonal antibody identified a 74-kDa antigen in different antigenic extracts of S. mansoni and Schistosoma haematobium and in the urine of infected individuals. In addition, a 30-kDa degradation product was identified only in the urine samples. On the basis of these results, FDA should be used as a rapid tool for the sensitive and specific diagnosis of Schistosoma infection.     

Constrained evolution of human immunodeficiency virus type 1 protease during sequential therapy with two distinct protease inhibitors

Human immunodeficiency virus type 1 (HIV-1) variants that have developed protease (PR) inhibitor resistance most often display cross-resistance to several molecules within this class of antiretroviral agents. The clinical benefit of the switch to a second PR inhibitor in the presence of such resistant viruses may be questionable. We have examined the evolution of HIV-1 PR genotypes and phenotypes in individuals having failed sequential treatment with two distinct PR inhibitors: saquinavir (SQV) followed by indinavir (IDV). In viruses where typical SQV resistance mutations were detected before the change to IDV, the corresponding mutations were maintained under IDV, while few additional mutations emerged. In viruses where no SQV resistance mutations were detected before the switch to IDV, typical SQV resistance profiles emerged following the introduction of IDV. We conclude that following suboptimal exposure to a first PR inhibitor, the introduction of a second molecule of this class can lead to rapid selection of cross-resistant virus variants that may not be detectable by current genotyping methods at the time of the inhibitor switch. Viruses committed to resistance to the first inhibitor appear to bear the "imprint" of this initial selection and can further adapt to the selective pressure exerted by the second inhibitor following a pathway that preserves most of the initially selected mutations.     

Securing urethral catheters in patients undergoing urethrovesical anastomosis

OBJECTIVE: Securing urethral catheters for the optimal healing of and prevention of extravasation at the urethrovesical anastomosis. METHOD: This article describes the technique that we use to help secure Foley catheters or replace them if necessary. CONCLUSION: In the rare patients where disruption of the anastomosis or loss of the catheter prematurely takes place, the nylon suture can be used to replace the catheter without jeopardizing the anastomotic line.     

Augmentation of human and rat lenticular glutathione in vitro by prodrugs of gamma-L-glutamyl-L-cysteine

A marked age-related decrease in glutathione (GSH) levels as well as depression of gamma-glutamylcysteine synthetase activity are factors that are believed to render the aged lens more susceptible to oxidative stress and, therefore, to cataractogenesis. Providing gamma-L-glutamyl-L-cysteine, the dipeptide precursor of GSH, would effectively bypass the compromised first step in its biosynthesis and should protect the lens from GSH depletion. Accordingly, some bioreversible sulfhydryl-, amino-, and C-terminal carboxyl-protected prodrug forms of this dipeptide were prepared. Sulfhydryl protection was in the form of an acetyl thioester, while the carboxyl group was protected as the ethyl ester. These prodrugs were evaluated for their GSH-enhancing activity in cultured human and rat lenses in vitro using an assay that measured the incorporation of [14C]glycine into lens GSH. Ethyl S-acetyl-gamma-L-glutamyl-L-cysteinate (2) raised GSH levels in human lenses by 25% and in rat lenses by >150%. These data suggest that 2 may have potential as an anticataract agent since ethyl gamma-L-glutamyl-L-cysteinate (1a), the des-S-acetyl analog of 2, had been shown (by others) to protect against experimental rodent cataracts. GSH augmentation by 1a was 2% in human lenses and 25% in rat lenses, considerably less than that shown by 2.     

Tactile evaluation of the response to double burst stimulation decreases, but does not eliminate, the problem of postoperative residual paralysis

BACKGROUND: Routine perioperative monitoring with accelero-myography might prevent residual block, whereas routine tactile evaluation of the response to train-of-four (TOF) nerve stimulation does not. The purpose of this prospective, randomised and blinded study was to evaluate the effect of manual evaluation of the response to double burst stimulation (DBS3.3) upon the incidence of residual block. METHODS: Sixty adult patients scheduled for elective abdominal surgery were included in the study. Pancuronium 0.08 to 0.1 mg kg-1 was given for relaxation and tracheal intubation. For maintenance of neuromuscular block, pancuronium 1-2 mg was administered. The patients were randomly allocated into two groups. In group DBS (double burst stimulation) the degree of block during anaesthesia was assessed by manual evaluation of the response to TOF nerve stimulation. During reversal, when no fade was detectable in the TOF response, the stimulation pattern was changed to DBS3.3. The trachea was extubated when the anaesthetist judged the neuromuscular function to have recovered adequately and no fade in the DBS3.3 response could be felt. In group CC (clinical criteria) patients were managed without the use of a nerve stimulator, and the level of neuromuscular block and reversal were evaluated solely on the basis of clinical criteria. In both groups, the TOF ratio was measured by mechanomyography immediately after tracheal extubation. Also, the ability to sustain head lift for 5 s, to protrude the tongue, to open the eyes, and to lift one arm to the opposite shoulder were tested. RESULTS: The TOF ratio, as measured immediately after tracheal extubation, was significantly lower in group CC than in group DBS (means: 0.68 and 0.78, respectively), and the incidence of residual neuromuscular block defined as a TOF ratio < 0.7 was significantly higher in group CC than in group DBS (57 and 24%, respectively). The time from the first TOF measurement until the TOF ratio reached 0.8 was significantly longer in group CC than in group DBs (means: 11.5 and 6.2 min, respectively). No significant differences between the two groups of patients were found in duration of anaesthesia, in times from end of surgery to injection of neostigmine, tracheal extubation or TOF ratio 0.8, in dose of pancuronium, or in any other postoperative variable. CONCLUSION: Routine perioperative manual evaluation of the responses to TOF and DBS3.3 decreased the incidence and the degree of residual block following the use of pancuronium. It did not, however, exclude clinically significant residual paralysis, nor did it influence the amount of pancuronium used during the operation, the duration of anaesthesia or the time from end of surgery to tracheal extubation or to sufficient recovery of neuromuscular function (TOF = 0.8).     

Striatal dopamine dynamics are altered following an intranigral infusion of iron in adult rats

Exercise has a noted effect on skin blood flow and temperature. We aimed to characterize the normal skin temperature response to exercise by thermographic imaging. A study was conducted on ten healthy and active subjects (age=25.8+/-0.7 years) who were exposed to graded exercise for determination of maximal oxygen consumption (VO2 max), and subsequently to constant loads corresponding to 50%, 70%, and 90% of VO2 max. The skin temperature response during 20 min of constant load exercise is characterized by an initial descending limb, an ascending limb and a quasi-steady-state period. For 50% VO2 max, the temperature decrease rate was - 0.0075+/-0.001 degrees C/s during a time interval of 390+/-47 s and the temperature increase rate was 0.0055+/-0.0031 degrees C/s during a time interval of 484+/-99 s. The level of load did not influence the temperature decrease and increase rates. In contrast, during graded load exercise, a continuous temperature decrease of -0.0049+/-0.0032 degrees C/s was observed throughout the test. In summary, the thermographic skin response to exercise is characterized by a specific pattern which reflects the dynamic balance between hemodynamic and thermoregulatory processes.