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.     

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.     

Conservative treatment of neonatal hydronephrosis.

From February 1990 to January 1991, 19 cases of hydronephrosis in children of less than one year of age were managed at Mackay Memorial Hospital. In the majority of these patients, there were evident causes such as ureteropelvic junction stenosis, ureterovesical reflux or a posterior urethral valve for which definite therapeutic measures were performed. However, some cases had no obvious origins and the hydronephrosis was speculated to be from nonobstructive or physiologic dilatation of the kidneys. The conventional tools, such as intravenous pyelogram or renal ultrasound, which comprise the mainstay of diagnosis, provide limited information on renal functional status. Recent introduction of the Tc-99m diethylene triamine penta-acetic acid (DTPA) diuretic renal scan has enabled us to distinguish between obstructive and nonobstructive hydronephrosis and helps us to determine whether or not surgery is necessary. In the past year, eight patients with hydronephrosis of less than one year of age were diagnosed as nonobstructive after a series of evaluations using renal ultrasound, voiding cystourethrography (VCUG) and Tc-99m DTPA diuretic renal scan. Follow-up studies by echography or DTPA renal scan revealed spontaneous resolution of the dilated collecting systems in these cases and confirms our belief that some hydronephrosis in neonates and infants may resolve spontaneously and may just be a manifestation of physiologic change during development. The value of the Tc-99m DTPA diuretic renal scan in the diagnosis of obstructive uropathy is discussed.     

Induced luteolysis in the primate: rapid loss of luteinizing hormone receptors

The molecular mechanisms involved in luteolysis are still unclear in the primate. This study aimed to investigate the effect of induced luteolysis on the ovarian luteinizing hormone (LH) receptor and the steroidogenic enzyme, 3beta-hydroxysteroid dehydrogenase (3beta-HSD) in the marmoset monkey. Luteolysis was induced in the mid-luteal phase either directly by systemic prostaglandin F2alpha (PGF2alpha), or indirectly by LH withdrawal using systemic gonadotrophin releasing hormone antagonist (GnRHant) treatment. The LH receptor was studied by isotopic mRNA in-situ hybridization and in-situ ligand binding and 3beta-HSD expression was studied using isotopic mRNA in-situ hybridization and immunohistochemistry. Induced luteolysis was associated with a reduction in the expression of LH receptor (P < 0.0001) and 3beta-HSD mRNA, closely followed by a reduction in the LH receptor (P < 0.05) and 3beta-HSD protein concentrations within 24 h. There were no differences in the findings whether luteolysis was induced with PGF2alpha or GnRHant. This study shows that disparate mechanisms to induce luteolysis in the primate result in an identical rapid loss of the LH receptor and 3beta-HSD. In conclusion, induced luteolysis leads to rapid loss of the steroidogenic pathway in luteal cells.