Discrete time optimal control of linear time-delay systems

A discrete time optimal control for linear time-delay systems is developed to ensure that all closed-loop eigenvalues will lie inside a circular region centred at (β;, 0) with radius α. It is shown that by suitable manipulations the problem can be reduced to a standard discrete time quadratic regulator problem. An illustrative example is included to demonstrate the applicability of the proposed method.     

Radiation dose reduction during hysterosalpingography: an application of scanning-beam digital radiography

Hysterosalpingography was performed in 31 patients by means of a low-dose scanning-beam digital radiographic system. The technique permits adequate evaluation of gynecologic abnormalities while allowing significant reduction in radiation: 2.4-mR (6.1 X 10(-7) C/kg) exposure to the skin and 0.7-mrad (7 X 10(-6) Gy) mean dose to the ovaries per image obtained. Sixteen patients demonstrated readily recognizable and documented abnormalities, corroborated by laparoscopy, laparotomy, or other supportive evidence.     

Modified Nile red staining method for improved visualization of neutral lipid depositions in stratum corneum.

The neutral lipids existing in the intercellular spaces of the stratum corneum (SC) provide a permeability barrier to prevent water loss. Nile red is the most sensitive lipid stain for tissue sections. However, due to the extremely flattened morphology of corneocytes and the resolution limits of the light microscope, Nile red staining is seldom used as a fluorescent probe for the lipid-rich SC. In this study, we modified the traditional method for visualization of intracellular lipid by adding 4% potassium hydroxide after Nile red staining. This modified method not only allowed visualization of lipids existing in the intercellular membrane regions and the lateral junctions of the adjoining corneocytes, but also clearly demonstrated small lipid droplets within pathological corneocytes. These features were not observed with the traditional staining method. Thus, this modified Nile red staining method greatly improved the resolution of the SC lipids under light microscopy and should be useful for studying lipid depositions in both normal and pathological SC.     

Detection ofHelicobacter pylori in gastric biopsy tissue by polymerase chain reaction

To evaluate the sensitivity of a polymerase chain reaction (PCR) assay using nested primers in detectingHelicobacter pylori, gastric tissue biopsy specimens were collected on endoscopy from 17 patients with a duodenal ulcer. DNA was extracted by phenol/chloroform treatment or boiling in water, and then subjected to a nested PCR using two primer pairs from the urease gene ofHelicobacter pylori. Fourteen of the 17 patients were positive forHelicobacter pylori using DNA samples extracted by either method. The PCR results correlated well with the results of an enzyme immunoassay to detect IgG antibody. However, there were two culture negative patients. The three PCR negative patients were both culture negative and serologically negative. DNA from 9 of the 14 patients was randomly selected and subjected to semiquantification by serial dilutions, and then PCR. The results showed that phenol/chloroform extraction yielded 10–1000 times more DNA than the boiling method. It is concluded that the PCR assay is a rapid and sensitive method for detectingHelicobacter pylori, and that phenol/chloroform extraction is superior to simple boiling in obtaining DNA samples for PCR.     

Depressed host immunity in a case of metachronous primary uterine papillary serous carcinoma and non-Hodgkin''s lymphoma

Metachronous primary malignant tumors of uterine papillary serous carcinoma (UPSC) and non-Hodgkin's lymphoma (NHL) are rare. UPSC is a clinically aggressive and morphologically distinctive variant of endometrial carcinoma. We describe the clinical features of a 63-year-old patient with UPSC that was found 2 years after chemotherapy for malignant lymphoma of neck, stage IV and 5 months after radiation therapy for recurrence. This patient had undergone staging surgery and postoperative radiation for UPSC. One month after completion of radiotherapy, the patient expired due to persistence of the disease. The association between host immunity and UPSC is rarely described in the literature. Immunological profiles of this patient, with compositional changes of natural killer, B, and T cell, dramatically altered the percentage of CD4(+) T cell, CD8(+) T cell, and CD4/CD8 ratio, signifying depressed host immunity. Immunological profile of this patient stressed the issue of depressed host immunity and associated malignancies.