Inhibition of Natural Killer Cell Cytotoxicity by Cell Growth-related Molecules

Certain MHC class I molecules on target cells are known to inhibit the cytotoxic action of NK cells. By using monoclonal antibody (mAb) Cho-1, we have found inhibitory non-MHC class I cell surface molecules that are noncovalently-associated with 200 kDa and 40 kDa antigens. Poly I-C-induced rat NK cells were not cytotoxic to rat fetus-derived fibroblast WFB cell line. In contrast, NK cells were cytotoxic to H- ras oncogene-induced transformants of WFB, W14 and W31. FACS analysis indicated that mAb Cho-1 reacts with WFB, but not with W14 and W31 cells. Thus, this antigen may disappear concomitantly with cell growth and transformation. Cho-1 antigens were also expressed on other NK-resistant lines, such as mouse BALB3T3 fibroblast, EL-4 lymphoma and human fibroblast HEPM. However, they were not expressed on NK-sensitive mouse YAC-1 and H- ras transformant (Brash) of BALB3T3 cells. Furthermore, treatment of target cells with IFN-γ clearly induced the cell surface expression of Cho-1 antigens, and conferred a resistance to NK cytolysis on target cells. These data strongly suggest that Cho-I antigen expression may correlate with target cell susceptibility to NK cells. Indeed, treatment of NK-resistant WFB as well as HEPM cells with F(ab')₂ fragments of mAb Cho-1 resulted in the acquisition of susceptibility to NK cytolysis. Cho-1 antigens may be novel molecules that regulate the NK resistance of cells.     

Long-term visual prognosis of choroidal neovascularization in high myopia: a comparison between age groups

OBJECTIVE: To analyze visual outcome in highly myopic patients of different age groups with choroidal neovascularization (CNV). DESIGN: Retrospective observational case series. PARTICIPANTS: We reviewed the medical records of 63 consecutive patients (73 eyes) with myopic CNV. The patient population was divided into two groups according to age at onset of CNV (< or =40 and >40 years old). INTERVENTION: Demographic and clinical data were obtained from the patients' medical records. MAIN OUTCOME MEASURES: Visual acuity at least 3 years after CNV diagnosis. RESULTS: Group 1 (< or =40 years old) consisted of 22 patients (26 eyes), and group 2 (>40 years old) consisted of 41 patients (47 eyes). Throughout the follow-up period, group 1 retained better visual acuity than group 2. Almost half the patients in group 1 retained a final visual acuity better than 20/40. No significant change occurred in the logarithm of the minimum angle of resolution (logMAR) in group 1 during follow-up. Group 2 had worse visual acuity at the initial evaluation than did group 1, and a statistically significant worsening of logMAR was found during the follow-up period. More than half of the patients in group 2 had a final visual acuity less than 20/200. In addition, group 2 had a larger area of CNV, and chorioretinal atrophy was more frequently seen after the regression of CNV than in group 1. CONCLUSIONS: The visual prognosis of myopic CNV is influenced by age at onset. The results of this study indicate that patient age at the time of onset of myopic CNV should be considered when determining the therapeutic course.     

Optical coherence tomography of choroidal neovascularization in high myopia

AIM: To investigate morphologic changes in the eye with choroidal neovascularization (CNV) in high myopia using optical coherence tomography (OCT). METHODS: Optical coherence tomography was performed in 35 patients (42 eyes) with myopic CNV. Myopic CNV was divided into active, scar, or atrophic stages based on funduscopic and fluorescein angiographic findings. The characteristics of OCT findings in each stage were identified. RESULTS: In the active stage (11 eyes), OCT clearly displayed a neovascular membrane as a highly reflective dome-like elevation above the retinal pigment epithelium (RPE). No apparent subretinal fluid accumulation around the CNV was identified. In the scar stage (12 eyes), only the surface of the CNV showed high reflectivity, which was markedly attenuated below the surface. In the atrophic stage (19 eyes), the CNV had become totally flat and chorioretinal atrophy around the regressed CNV showed high reflectivity. CONCLUSIONS: Optical coherence tomography demonstrated characteristic features at each stage of myopic CNV. Optical coherence tomography appears to be useful in evaluating the stage and activity of myopic CNV.     

Surface dyslexia in a Japanese patient with semantic dementia: evidence for similarity-based orthography-to-phonology translation

We studied the reading performance of a Japanese-speaking patient, TI, with bilateral but asymmetrical (left more than right) temporal-lobe atrophy, severe anomia, and poor word comprehension. Most Japanese kanji characters correspond to several different legitimate pronunciations in different contexts, with varying degrees of correspondence consistency. TI made many errors in reading aloud words that violate statistically typical character-sound correspondences, especially for less common words, but had relatively preserved ability to read aloud strings in which the assignment of the typical pronunciation for each component character yields the correct pronunciation for the whole word. The degree of consistency of character-sound correspondences affected his performance on both words and nonwords in a graded manner. One interpretation is that TI's surface dyslexic reading reflects intact direct computation of phonology from orthography, but without the additional constraint from word meaning that is, in this framework, considered critical for correct pronunciation of lower-frequency words with atypical character-sound correspondences. Another interpretation is that TI's performance reflects partially damaged lexical knowledge of whole-word orthography and phonology, coupled with spared sublexcal knowledge of character-sound correspondence rules. Whichever of these interpretations is preferred, this study offers the most detailed information yet available on the characteristics of surface dyslexia in Japanese.     

A case of colon cancer with multiple liver metastases and lymph nodes metastases successfully treated by 5'-deoxy-5-fluorouridine

In a 79-year-old man with ascending colon cancer, multiple liver metastases were detected by computer tomography. The patient underwent right hemicolectomy. Paraaortic lymph nodes metastases were found intraoperatively. After surgery, 5'-deoxy-5-fluorouridine (5'-DFUR) was administered orally at 600 mg daily. Abdominal CT showed disappearance of the liver metastases 6 months after operation. At a follow-up exam 24 months after the beginning of the chemotherapy, the patient remained in remission and reported no side effects. We consider oral administration of 5'-DFUR to be a useful treatment for advanced colon cancer.     

Neo-adjuvant chemotherapy with carmofur for colorectal cancer--a multi-institutional randomized controlled study

The efficacy and safety of preoperative chemotherapy with carmofur (HCFU) for colorectal cancer were evaluated in a randomized controlled study involving 63 institutes in the Kanto area. Patients aged 75 or younger with Dukes' B or C colorectal cancer were eligible if curative surgery was expected. In the end, 326 were eligible from 405 consecutive colorectal cancer patients. Patients in both the control (n = 162) and the new treatment group (n = 164) were given intravenous mitomycin C (MMC) 6 mg/m2 on day 0 and 7 after surgery and HCFU 300 mg/day orally from day 14 for a year. Patients in the new treatment group were also given oral HCFU for 14 days or more prior to surgery. All 326 patients were followed for 5 years or longer. Five-year overall and disease-free survival rates were not significantly different between the two groups (75.4% and 71.6% for the control, and 71.8% and 71.5% for the study group, respectively). In the subset analysis, neither cancer site nor nodal status affected the differences in overall- and disease-free survival rates between the groups. The present findings show no additional efficacy of preoperative chemotherapy with HCFU in survival from advanced colorectal cancer. Further investigations in terms of patient selection, treatment regimen, combined use of radiotherapy, and other factors would be required to determine the significance of preoperative chemotherapy against advanced colorectal cancer.     

Estrogen blocks 3-nitropropionic acid-induced Ca2+i increase and cell damage in cultured rat cerebral endothelial cells

Systemic administration of 3-nitropropionic acid (3-NPA, a mycotoxin) induces brain damage accompanied by disturbance in the blood-brain barrier (BBB). Since the endothelial cells are important components of the BBB and the first target of a systemic intoxication, in the present study, the effect of 3-NPA on primary cultured rat brain endothelial cells (rBECs) was examined by studying intracellular Ca(2+) ([Ca(2+)](i)) response using imaging techniques with fura-2. rBECs were prepared using a method of Kis et al. [Eur. J. Pharmacol. 368 (1999) 35-42] and Szabo et al. [Neurobiology 5 (1997) 1-16]. Almost all cells were immunoreactive to antibody against the factor VIII-related antigen (von-Willebrand factor). They showed a typical dose-dependent increase of [Ca(2+)](i) in response to ATP or bradykinin. Low concentrations of 3-NPA (1.7 mM, 3.4 mM) caused no changes, and a medium concentration (6.8 mM) increased the [Ca(2+)](i) gradually and progressively, and the increase was reversed incompletely back to the resting level after washing. A high concentration (13.6 mM) increased the [Ca(2+)](i) irreversibly. These elevations of [Ca(2+)](i) were absent in a Ca(2+)-free medium. In endothelial cells treated with 17beta-estradiol (above 10(-5) M) or with a selective estrogen receptor modulator, tamoxifen (5 x 10(-7) M), no elevation of [Ca(2+)](i) was observed with 3-NPA treatment. The response to ATP was impaired after application of 3-NPA, but it was preserved by cotreatment with 17beta-estradiol or tamoxifen. An estrogen receptor antagonist ICI 182,780 inhibited these effects by 17beta-estradiol or tamoxifen. Lysosomal neutral red uptake and TUNEL experiments revealed the necrotic but not apoptotic cell death at least in this acute stage. Data indicate that a medium to high concentration of 3-NPA induces damage on rBECs as revealed by an accumulation of [Ca(2+)](i), but the damage was protected by cotreatment with 17beta-estradiol or tamoxifen, suggesting that estrogen may be protective for the brain vascular damage via estrogen receptor.     

Increased expression of mRNAs for microtubule disassembly molecules during nerve regeneration

The mRNA expression of the microtubule disassembly molecules (SCG10, stathmin, SCLIP and RB3) in response to nerve injury was examined using a rat hypoglossal nerve injury model. After nerve injury prominent increase in mRNA expression of SCG10, stathmin and RB3 was observed, while only slight increase in SCLIP mRNA was observed in injured motor neurons. The increase in SCG10 and RB3 mRNA expression was quicker than that of stathmin and SCLIP. All the elevated signals decreased gradually to control levels by 4 weeks after nerve injury.     

Enhancing mechanism of Labrasol on intestinal membrane permeability of the hydrophilic drug gentamicin sulfate.

The aim of this study was to clarify the mechanism by which caprylocaproyl macrogol-8 glyceride (Labrasol) enhances the intestinal absorption of gentamicin sulfate (GM), a drug that has poor permeability but relatively high solubility. We studied the following characteristics: (i) the phase behavior of Labrasol in aqueous solution, (ii) the affinity of GM to Labrasol micelles, and (iii) the interaction between Labrasol and membrane lipids. We measured the critical micelle concentration of Labrasol in aqueous solution to be approximately 0.01%. The average diameters of Labrasol micelles in 2% and 25% solutions were approximately 10 nm and 20 nm, respectively, indicating that micelles increase in size with increasing Labrasol concentration. Although GM dissolved in 5% Labrasol solution was dialyzable, GM dissolved in either 25% or 50% Labrasol solutions was not, suggesting that GM exists in the hydrophilic region of the Labrasol micelle or in the high affinity region of the micelle surface where GM is retained. In membrane permeability experiments and electrophysiological studies conducted with rat ileum, only 25% Labrasol solution enhanced GM permeability, but did not remarkably affect membrane resistance. Furthermore, Labrasol increased membrane lipid fluidity as determined by fluorescence anisotropy in porcine intestinal brush border membrane liposomes. These results suggest that high concentrations of Labrasol solution enhance membrane permeability of GM via a transcellular rather than a paracellular route. We propose the following mechanism: Labrasol micelles grow when the concentration of Labrasol exceeds 20%, at which point GM shows high affinity for the hydrophilic region of the micelles. Since Labrasol micelles increase membrane lipid fluidity, the membrane permeability of GM is concomitantly enhanced.