Immunologic phenotype of hosts orally immunized with corneal alloantigens

PURPOSE: To evaluate the immunologic phenotype of hosts tolerized by oral administration of corneal alloantigens. METHODS: CB6F1 mice were tolerized by oral administration of allogeneic C3H/Hej corneal epithelial and endothelial cells before receiving heterotopic C3H/Hej corneal allografts. C3H-specific cytotoxic T-lymphocyte (CTL), delayed-type hypersensitivity (DTH), and mixed-lymphocyte responses were evaluated in orally tolerized and control mice. Cytokine profiles of Peyer's patch cells from orally tolerized mice were determined by enzyme-linked immunosorbent assay and mink lung cell culture bioassay. RESULTS: Oral administration of corneal cells produced a profound inhibition of allospecific CTL, DTH, and mixed-lymphocyte responses. Conjugation with the B subunit of cholera toxin markedly increased the tolerizing activity of corneal endothelial cells, so that a single dose of cholera toxin-conjugated corneal cells inhibited alloimmune responses to the same degree as 10 doses of corneal cells unconjugated with cholera toxin. Peyer's patch cells from orally tolerized mice produced reduced quantities of interferon-gamma and interleukin-2 but produced increased amounts of transforming growth factor-beta and interleukin-10 compared with concentrations in normal control animals. CONCLUSIONS: Oral administration of cholera toxin-conjugated corneal cells produces a dose-dependent inhibition of allospecific CTL, DTH, and mixed-lymphocyte responses. Orally induced inhibition of cell-mediated immune responses to corneal alloantigens is correlated with a sharp increase in the secretion of transforming growth factor-beta and interleukin-10 and a concomitant suppression of interleukin-2 and interferon-gamma. The well-recognized immunosuppressive characteristics of transforming growth factor-beta and interleukin-10 are suggestive that orally induced tolerance to corneal alloantigens is mediated by these cytokines.     

Clear cell papulosis of the skin

Clear cell papulosis is a new entity first described in 1987. To date, six patients have been reported: all were young Taiwanese children. The disease is characterized clinically by multiple small, whitish maculopapules distributed along the milk line and by the presence of large, benign pagetoid cells in the epidermis resembling the clear cell of the nipple. The significance of this entity lies in its potential histogenetic link with Paget's disease of the skin. We report four new Taiwanese patients, three girls and one boy, aged between 21 months and 4 years. Two were sisters. Small hypopigmented macules first appeared on the pubis. They were eventually distributed bilaterally along the milk line but were most numerous in the public area. The disease may easily be overlooked when the macules are tiny or few in number and thus display no clear milk-line distribution, or when they occur in white-skinned individuals. Histologically, solitary large clear cells with large, round pale nuclei were detected in the basal layer of the hypomelaninized epidermis. The numbers of clear cells varied on haematoxylin and eosin staining and were only small in two patients. The cytoplasm of the clear cells was decorated by antikeratin AE1 and anticarcinoembryonic antigen antibodies. AE1 was the best marker of the clear cell. Some of the AE1-positive cells were tadpole-like in shape and were situated well above the basal layer. Ultrastructurally, large clumps of disintegrated or vacuolated mucin granules were present in the cytoplasm of the clear cells. The melanocytes appeared normal; the suprabasal keratinocytes were essentially devoid of melanosomes. The pathological findings in the present study support the hypothesis that these clear cells are an aberrant derivative of sweat gland cells in the epidermis and are potentially the precursor cells giving rise to mammary and extramammary Paget's disease. The differential diagnosis includes chicken pox scars, idiopathic guttate hypomelanosis, hypomelanotic tinea versicolor, anetoderma and early, hypopigmented lesions of Paget's disease.     

The blood contribution to early myocardial reperfusion injury is amplified in diabetes

Cardiovascular disease is excessive in diabetes, and blood cell function is altered. It is not clear, however, if alterations in the blood contribute to the excessive cardiovascular complications of this disease. In this study, we compared the contribution of nondiabetic and diabetic blood to myocardial reperfusion injury. The recovery of cardiac contractile function following no-flow ischemia was studied in isolated diabetic and nondiabetic rat hearts perfused with diabetic or nondiabetic diluted whole blood. Hearts were isolated from 10- to 12-week-old diabetic (streptozotocin, 65 mg/kg, i.v.) and nondiabetic rats and perfused with a Krebs-albumin-red cell solution (K2RBC, Hct 20%). After a 30-min pre-ischemic control period, during which cardiac pump function was evaluated, diabetic and nondiabetic hearts were perfused for 5 min with diluted whole blood (DWB; Hct 20%) collected from either diabetic or nondiabetic donor animals. Coronary flow was then stopped and the hearts subjected to 30 min of no-flow ischemia. Following ischemia, the hearts were reperfused with the K2RBC perfusate. Cardiac contractile function was evaluated throughout the 60-min reperfusion period. Six groups were studied: diabetic and nondiabetic hearts perfused before ischemia with either K2RBC, nondiabetic DWB (NDDWB), or diabetic DWB (DDWB). Perfusion with DWB prior to ischemia impaired the recovery of contractile function in all cases. The impairment to recovery was greater with DDWB than with NDDWB. Although diabetic hearts perfused with K2RBC throughout recovered quite well, the effect of DDWB perfusion in the diabetic hearts was dramatic. In an effort to determine why diabetic blood impaired functional recovery, measures of blood filterability and the generation of reactive oxygen species (ROS) were made. We found that diabetic blood was less filterable than nondiabetic blood; that is, the diabetic blood cells tended to plug the 5-microm filter pores more readily than the nondiabetic blood cells. Also, we found that the diabetic blood was capable of generating significantly greater ROS (oxygen free radicals) than nondiabetic blood (P < 0.05). These findings suggest that the blood contribution to myocardial reperfusion injury is amplified in diabetes. A tendency for diabetic blood cells to plug capillary-sized pores and show enhanced oxygen free radical production may account for the excessive contribution of diabetic blood to reperfusion injury in the heart.     

In Vitro antimicrobial susceptibilities of Streptococcus pneumoniae isolated from two teaching hospitals in Taiwan, 1989-1995

The susceptibility of 46 pneumococcal isolates collected during October 1989 to May 1995 from National Taiwan University Hospital and Taipei Municipal Yang Ming Hospital was studied. Among these isolates, the resistant rate of penicillin G was 21.7%; the penicillin G-resistant strains were more frequently resistant than the penicillin-sensitive strains to other beta-lactam antimicrobial drugs. The minimum bactericidal concentrations (MBCs) of penicillin G for all isolates were equal to, or one dilution higher than, minimum inhibitory concentrations (MICs). Three strains were false positive for penicillin resistance among isolates of Streptococcus pneumoniae screened with oxacillin. On the other hand, resistance to penicillin G was often independent of resistance to erythromycin. Vancomycin was the most active agent tested.     

Molecular structural basis of ligand selectivity for 5-HT2 versus 5-HT1C cortical receptors

A molecular structural criterion of ligand selectivity for the 5-HT2 versus 5-HT1C receptor was hypothesized on the basis of radioligand binding data. Despite the large number of compounds which have been tested at both receptors, analysis of published data led to the identification of only five agents which are greater than 10-fold selective for the 5-HT2 versus the 5-HT1C receptor. Comparison of the two-dimensional structures revealed that, although these five compounds represent three distinct structural classes, they share a common structural feature located in the region hypothesized to be involved in receptor binding: a carbonyl or carboxyl oxygen interposed spatially between an aromatic ring and nitrogen atom. This structural feature was used to predict the relative selectivity of compounds that had not previously been analyzed at both the 5-HT2 and 5-HT1C receptors. All six drugs tested which contain the identified reactive carbonyl or carboxyl group were found to be selective for the 5-HT2 versus the 5-HT1C receptor with selectivity ratios ranging from 26 to 380. By contrast, three agents which are structurally similar but do not contain the reactive carbonyl or carboxyl group displayed equally high affinity for both receptor binding sites. Since the physiological roles of the 5-HT2 and 5-HT1C receptor are markedly different, it would be of potential clinical and scientific value to utilize this molecular structural feature to further identify chemical compounds which would selectively interact with only one of the two receptors.     

Detection and deletion of motion artifacts in electrogastrogram using feature analysis and neural networks

Electrogastrogram is a surface measurement of gastric myoelectrical activity, and electrogastrography has been an attractive method for physiological and pathophysiological studies of the stomach due to its noninvasive nature. Motion artifacts, however, ruin the electrogastrogram (EGG), and make the analysis very difficult and sometimes even impossible. They must be eliminated from EGG signals before analysis. Up to now, this can only be done by visual inspection, which is not only time-consuming but also subjective. In this study, a method using feature analysis and neural networks has been developed to realize automatic detection and elimination of the motion artifacts in EGG recordings by computer. Experiments were conducted to investigate the characteristics of different motion artifacts. Useful features were extracted, and different combinations of the features used as the input of the neural network were compared to obtain the optimal performance for the detection of motion artifacts using the artificial neural network.