Factors affecting the total occlusion time in eyes with hyperopic anisometropic amblyopia

BACKGROUND

Amblyopia treatment by occluding the healthy eye is known to be effective during a sensitive critical period. This study aims to clarify the factors for the total occlusion time (TOT) required for the amblyopic eye to achieve a normal visual acuity (VA) level of 1.0 (0.0 logMAR equivalent). This could contribute to an efficient treatment plan for eyes with hyperopic anisometropic amblyopia.

METHODS

Subjects were 58 patients (26 boys and 32 girls; age range, 3.6-9.2, average, 5.8 ± 1.3 years) with hyperopic anisometropic amblyopia. All the subjects had initially visited and completed occlusion therapy with improved VA of 1.0 or better in the amblyopic eye at Kindai University Hospital between January 2007 and March 2017. Using the subjects' medical records, we retrospectively investigated five factors for the TOT: the age at treatment, the initial VA of the amblyopic eye, refraction of the amblyopic eye, anisometropic disparity, and the presence of microstrabismus. Patient's VA improvement at one month after treatment was also evaluated to confirm the effect of the occlusion therapy.

RESULTS

The initial VA of the amblyopic eye ranged from 0.1 to 0.9 (median, 0.4). The TOT ranged from 140 to 1795 (median, 598) hours with an average daily occlusion time of 7 hours. The initial VA of the amblyopic eye and presence of microstrabismus were the significant factors for the TOT (p < 0.01). To achieve VA of 1.0 or better, patients with an initial VA of ≤ 0.3 in the amblyopic eye required a longer TOT. Moreover, patients with concomitant microstrabismus required a 1.7-fold longer TOT compared to those without microstrabismus.

CONCLUSION

Longer daily occlusion hours and early start of the treatment will be necessary for patients with poor initial VA or microstrabismus to complete occlusion therapy within the sensitive critical period.

Fundus autofluorescence, optical coherence tomography and electroretinography abnormalities in a patient with digoxin retinopathy that resemble those in KCNV2-associated retinopathy

BACKGROUND

Digoxin related retinal toxicity causes blurred vision, photophobia, central scotoma, color vision abnormality, and electroretinography (ERG) abnormalities. Here, we report a case with transient abnormalities in vison, in which fundus autofluorescence (FAF), optical coherence tomography (OCT), and ERG findings resembled those in KCNV2 (potassium voltage-gated channel modifier subfamily V member 2)-associated retinopathy.

CASE REPORT

An 89-year-old woman presented with complaints of acute blurred vision, nyctalopia, photophobia, and color vision abnormality. She received digoxin for tachycardia induced by atrial fibrillation for a month. The fundi showed a faint white ring at the fovea, which showed hyperfluorescence in FAF. OCT showed a thickened EZ in the macula. A dark-adapted (DA)-30 ERG showed a reduced and "squaring (trough-flattened)" a-wave, and a delayed, supernormal b-wave, resulting in a high b/a-wave amplitude ratio. The digoxin dose was reduced following an elevation in serum levels. Five weeks later, her visual acuities improved, and abnormal hyperfluorescence on FAF disappeared. After 6 months, no visual symptoms were reported. The ellipsoid-zone thickening in OCT improved; however, the b/a-wave amplitude ratio on DA-30 ERG remained high. The b-wave in LA-long-flash ERG was initially reduced, which improved after correction of serum level of digoxin.

CONCLUSIONS

The patient's clinical findings resembled those of patients with KCNV2-associated retinopathy or temporal hyperkalemia. These disorders appear to have a common pathogenesis, which may be related to abnormal extracellular potassium levels in the retina. The on-bipolar cells seemed to be more affected than the off-bipolar cells in digoxin related retinal toxicity.

The Association Between Improvement of Stereoacuity and Suppression in the Treatment of Anisometropic Amblyopia

Purpose

To investigate the association between stereoacuity and suppression during occlusion therapy for patients with anisometropic amblyopia.

Design

Retrospective study.

Patients and Methods

This study included 19 patients with hyperopic anisometropic amblyopia who underwent occlusion therapy. The mean age of the patients was 5.5 ± 1.4 years. The participants were evaluated for improvement in stereoacuity and suppression before beginning occlusion therapy, when the highest amblyopic visual acuity (VA) was achieved, during tapering, at the end of occlusion therapy, and at the final visit. Stereoacuity was evaluated using the TNO test or JACO stereo test. The presence of suppression was evaluated using circle No. 1 of the Stereo Fly Test or JACO results as the optotype.

Results

Of the 19 patients, 13 (68.4%) had suppression before occlusion, eight (42.1%) when the highest VA was achieved, five (26.3%) during tapering, and none at the final visit. Of the 13 patients with suppression before occlusion, 10 (76.9%) showed further improvement in stereoacuity when suppression disappeared, and nine had foveal stereopsis of 60 arcseconds. A significant association was confirmed between foveal stereopsis and suppression when the highest VA was achieved and during the tapering period (P<0.05, Fisher's exact test).

Conclusion

Suppression was observed even when the VA in amblyopic eyes reached the highest score. By gradually decreasing the duration of occlusion, suppression was eliminated, leading to the acquisition of foveal stereopsis.

Measurement of Fixational Eye Movements With the Head-Mounted Perimeter Imo

Purpose

Although visual field testing is conducted with the subject gazing at a fixation target, constant minute eye movements, called fixational eye movements, do occur during fixation. We examined dynamic changes in fixational eye movements associated with stimulus presentation during visual field testing.

Methods

We used the head-mounted perimeter imo, which is capable of measurement under binocular conditions, with the frame rate of its fixation monitoring camera improved to 300 Hz, to assess fixational eye movements in 18 healthy individuals. We measured changes in fixational eye movements during testing under monocular and binocular conditions and analyzed these changes based on the bivariate contour ellipse area (BCEA). We also assessed the changes in the horizontal and vertical microsaccade rates separately.

Results

Both the BCEA and horizontal microsaccade rates were higher at 400 to 600 msec after stimulus presentation than during stimulus presentation (P < 0.01). Additionally, the BCEA and vertical microsaccade rates were significantly lower in the binocular condition than in the monocular condition (P < 0.01 and P < 0.05, respectively). We did not observe a significant correlation between the test locations and microsaccade direction during visual field testing.

Conclusions

Fixational eye movements, especially vertical microsaccade rates, were lower in the binocular condition than in the monocular condition. Visual field testing under binocular conditions is a useful method for suppressing fixational eye movements and stabilizing the fixation during testing and may improve the reliability of the test results.

Translational Relevance

Visual field testing under binocular conditions can make the fixation more stable during the testing compared with monocular conditions.

Efficacies of preoperative prism adaptation test and monocular occlusion for detecting the maximum angle of deviation in intermittent exotropia

Background

The efficacies of prism adaptation test (PAT) and monocular occlusion (MO) and their optimal test durations to detect the maximum angles of deviation at near and distance in eyes with intermittent exotropia (IXT) were assessed and compared.

Methods

We retrospectively reviewed the medical records of 72 patients with IXT. All the patients had undergone the initial strabismus surgery between April 2015 and October 2018 and had been preoperatively tested by both PAT and MO performed on different days for 30 and 60 min. Near and distance deviations after 30 and 60 min of PAT and MO were compared to their baseline measurements obtained immediately after prism wear and before occlusion by alternate prism cover test. The near/distance measurements and required test duration to reveal the maximum deviation angle were also compared between PAT and MO.

Results

Compared with the baseline, the near deviation by PAT significantly increased after 30 (P < 0.05) and 60 (P < 0.01) minutes but not the distance deviation. However, the increase after 30 min was not significant. By MO, neither near nor distance deviation showed a significant difference from the baseline after 30 and 60 min. PAT showed a significantly larger near deviation than MO at 30 and 60 min, but a larger distance deviation by PAT was only observed at 30 min.

Conclusions

In patients with basic and convergence insufficiency types of IXT, a 30-minute PAT appears to be more effective than MO in revealing the maximum angle of deviation before strabismus surgery.

Utility of CLOCK CHART binocular edition for self-checking the binocular visual field in patients with glaucoma

BACKGROUND/AIMS

Car accidents caused by drivers unaware of their visual field (VF) defects under binocular vision have become an issue. We developed a simple self-check chart (CLOCK CHART binocular edition (CCBE)) to help patients with glaucoma recognise their abnormalities in the binocular VF and evaluated its usefulness.

METHODS

The chart has four targets displayed at 10°, 15°, 20° and 25° eccentricities. The examinee gradually rotates the chart 360° clockwise. At every 30°, the examinee confirms the fixation and indicates if all four targets can be seen. This study enrolled 88 eyes of 44 patients with glaucoma (mean age, 64.4±13.1 years) and 64 eyes of 32 visually normal individuals (mean age, 32.0±8.4 years). Except the CCBE test, static VF testing using the Humphrey field analyser (HFA) Swedish Interactive Threshold Algorithm-Standard 30-2 and binocular Esterman programmes was also performed for the subjects with glaucoma.

RESULTS

VF abnormality was defined as two or more contiguous points with a sensitivity of <10 dB within the central 30°. The CCBE test had sensitivities of 85% and 82% with respect to the HFA and Esterman results, respectively. We also used the British VF standards for Group 1 (car/motorcycle) drivers, and a sensitivity of 88% was obtained for the CCBE. The chart had a specificity of 100% for the visually normal subjects.

CONCLUSION

The CCBE test enables drivers with glaucoma to notice their VF abnormalities under binocular condition. The application of this simple self-check method appears promising for occasions such as driver licensing.

The interpretation of results of 10-2 visual fields should consider individual variability in the position of the optic disc and temporal raphe

Aims

To clarify the anatomical relation between the optic disc and temporal raphe and to examine how these are related to test points in the 10-2 visual field test pattern.

Subjects and methods

For 22 eyes of volunteers with normal vision (+0.75 D spherical equivalent 7.88 D), a volume scan was used to obtain en-face images from a plane fitted to the inner limiting membrane using optical coherence tomography (OCT). The clearest en-face retinal nerve fibre (RNF) image was chosen for each subject and superimposed on fundus photographs using blood vessels for alignment. Individual landmarks (disc, fovea and visual field blind spot) were then used to superimpose the Humphrey Field Analyzer 10-2 visual field on the OCT image to compare with the RNF image.

Results

The average disc–fovea–raphe angle was 169.4°±3.2°. Both the disc and temporal raphe were located above the horizontal midline (ie, were inferior in visual field space). For the 10-2 test pattern superimposed on the OCT image, in 54.5% of eyes, the temporal inferior test points adjacent to the horizontal midline mapped to the anatomical inferior hemifield. In 22.7% of eyes, nasal inferior test points adjacent to the horizontal midline mapped to the anatomical inferior hemifield. This mapping is opposite to typically assumed.

Conclusion

The position of the disc and raphe affects the mapping between structure and function with respect to superior and inferior hemifields. Individual differences in the position of the temporal raphe should be considered when mapping between structure and function for the 10-2 test pattern.

Influence of Test Distance on Stereoacuity in Intermittent Exotropia

AIMS

To investigate influence of test distance on stereoacuity in intermittent exotropia (X[T]) using the same test conditions for both near and far distances.

METHODS

Subjects were 38 consecutive patients with X(T). All the patients were between ages 6 and 15 years and had decimal visual acuity of 1.0 or better. Another inclusion criterion was presence of phoric condition at near and far distances. Stereoacuity was measured at a near distance of 40 cm and at a far distance of 5 m. The following test conditions were used for both test distances: separation of the two eyes using polarized glasses, and a target with a random dot pattern. All the stereograms had the same subtended angle of 2.5º, and binocular disparity of 480, 240, 120, and 60 arcsec. We used two stereogram types with crossed and uncrossed disparities.

RESULTS

Far stereoacuity of 38 subjects measured with the crossed disparity was significantly worse than near stereoacuity (P<0.05, Wilcoxon signed-ranks test), although 30 (78.9%) of the 38 subjects showed no differences in stereopsis between the near and far distances. Far stereoacuity of 38 cases measured with the uncrossed disparity was significantly worse than at near (P<0.05, Wilcoxon signed-ranks test), although 20 (52.6%) of the 38 subjects showed no differences between stereoacuity at near and far. In comparison of stereoacuity with crossed disparity and uncrossed disparity, stereoacuity with crossed disparity was significantly better than that with uncrossed disparity both at near and far (P<0.05, Wilcoxon signed-ranks test).

CONCLUSIONS

Stereoacuity in X(T) was different according to test distance when measured controlling subtended angle of stereogram at both distances. Far stereoacuity was significantly worse than near stereoacuity when measured using test targets with both crossed and uncrossed disparities. Additionally, stereoacuity measured with crossed disparity was better than that with uncrossed disparity at both distances.

Automatic identification of the temporal retinal nerve fiber raphe from macular cube data

We evaluated several approaches for automatic location of the temporal nerve fiber raphe from standard macular cubes acquired on a Heidelberg Spectralis OCT. Macular cubes with B-scan separation of 96-122 µm were acquired from 15 healthy participants, and "high density" cubes with scan separation of 11 µm were acquired from the same eyes. These latter scans were assigned to experienced graders for subjective location of the raphe, providing the ground truth by which to compare methods operating on the lower density data. A variety of OCT scan parameters and image processing strategies were trialed. Vertically oriented scans, purposeful misalignment of the pupil to avoid reflective artifacts, and the use of intensity as opposed to thickness of the nerve fiber layer were all critical to minimize error. The best performing approach "cFan" involved projection of a fan of lines from each of several locations across the foveal pit; in each fan the line of least average intensity was identified. The centroid of the crossing points of these lines provided the raphe orientation with an average error of 1.5° (max = 4.1°) relative to the human graders. The disc-fovea-raphe angle was 172.4 ± 2.3° (range = 168.5-176.2°), which agrees well with other published estimates.

Optical coherence tomographic findings at the fixation point in a case of bilateral congenital macular coloboma

Background

Congenital macular coloboma is a rare ocular disease that consists of atrophic lesions in the macula with well-circumscribed borders. We report the findings of spectral domain optical coherence tomography (SD-OCT) at the fixation point in a case of bilateral macular coloboma.

Case report

The subject is a 4-year-old boy. He visited our hospital at age 1 year and 4 months for the evaluation of strabismus. The fundus examination of both eyes showed round-shaped sharply-demarcated atrophic lesions involving the macula with large choroidal vessels and bared sclera at the base. Immunologic tests including toxoplasmosis, rubella, varicella, herpes virus, and human T-cell leukemia virus were all negative. At age 4 years and 1 month, cycloplegic refraction showed insignificant refractive errors and his best corrected visual acuity was 0.6 bilaterally. The SD-OCT showed a crater-like depression accompanying atrophic neurosensory retina, and the absence of retinal pigment epithelium and choroid. Examination of the fixation behavior by visuscope showed steady fixation with an area 0.5° nasal to the nasal edge of the atrophic lesion bilaterally. The SD-OCT findings at fixation area showed remaining normal retinal structures involving inner segment-outer segment (IS/OS) junction line.

Conclusion

The findings of SD-OCT have been shown to be useful in the diagnosis of macular coloboma. In the fixation point, the structure of retina and choroid were well preserved.

Structure-function mapping: variability and conviction in tracing retinal nerve fiber bundles and comparison to a computational model

PURPOSE

We evaluated variability and conviction in tracing paths of retinal nerve fiber bundles (RNFBs) in retinal images, and compared traced paths to a computational model that produces anatomically-customized structure-function maps.

METHODS

Ten retinal images were overlaid with 24-2 visual field locations. Eight clinicians and 6 naïve observers traced RNFBs from each location to the optic nerve head (ONH), recording their best estimate and certain range of insertion. Three clinicians and 2 naïve observers traced RNFBs in 3 images, 3 times, 7 to 19 days apart. The model predicted 10° ONH sectors relating to each location. Variability and repeatability in best estimates, certain range width, and differences between best estimates and model-predictions were evaluated.

RESULTS

Median between-observer variability in best estimates was 27° (interquartile range [IQR] 20°-38°) for clinicians and 33° (IQR 22°-50°) for naïve observers. Median certain range width was 30° (IQR 14°-45°) for clinicians and 75° (IQR 45°-180°) for naïve observers. Median repeatability was 10° (IQR 5°-20°) for clinicians and 15° (IQR 10°-29°) for naïve observers. All measures were worse further from the ONH. Systematic differences between model predictions and best estimates were negligible; median absolute differences were 17° (IQR 9°-30°) for clinicians and 20° (IQR 10°-36°) for naïve observers. Larger departures from the model coincided with greater variability in tracing.

CONCLUSIONS

Concordance between the model and RNFB tracing was good, and greatest where tracing variability was lowest. When RNFB tracing is used for structure-function mapping, variability should be considered.

Diffusion tensor feature in vasogenic brain edema in cats

We investigated the correlation between the changes in diffusion tensor magnetic resonance imaging, regional water content, and tissue ultrastructure after vasogenic brain edema induced by cortical cold lesioning. In this cat model, E3 in the white matter was dominantly increased while fractional anisotropy (FA) was significantly decreased 8 hours after cortical cold lesioning. This finding indicates that water diffusion in the cortical white matter mainly increased perpendicularly rather than parallel to the direction of the nerve fibers. Additionally, in the area where edema is mild or moderate (tissues with water content of 65% to 75%), FA in the chronic phase was significantly lower than that in the acute phase. Histological examination demonstrated disordered arrangement of nerve fibers, highly dissociated neuronal fibers due to extracellular accumulation of protein rich-fluid, and enlarged interfiber spaces in the acute phase.

Increased CCR4 expression on circulating CD4(+) T cells in ankylosing spondylitis, rheumatoid arthritis and systemic lupus erythematosus

Previous studies have suggested that CCR4 is particularly important in the selective recruitment of various subsets of leucocytes in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). In this study, we examined the percentage of CD4(+)/CCR4(+) T cells within circulating lymphocytes in active ankylosing spondylitis (AS), RA and SLE patients. The clinical significance of CCR4 expression as well as possible associations between the expression and serum levels of tumour necrosis factor (TNF)-alpha, interferon (IFN)-gamma and interleukin (IL)-10 were also examined. Our results showed that the percentage of CD4(+)/CCR4(+) T cells was significantly elevated in AS and RA patients as compared with normal controls. The percentage was also significantly higher in SLE patients who had received no treatment with glucocorticoids or cytotoxic drugs (untreated SLE) than that in controls. In addition, the percentage of CD4(+)/CCR4(+) T cells showed significant positive correlations with the Bath ankylosing spondylitis disease activity index (BASDAI) in AS and with the SLE disease activity index (SLEDAI) in untreated SLE. Of all the cytokines examined, the elevated serum IL-10 level was closely correlated with the percentage of CD4(+)/CCR4(+) T cells in AS, RA and untreated SLE. These results suggest that CCR4 may be crucial in the pathogenesis of AS, RA and SLE. The percentage of CD4(+)/CCR4(+) T cells can serve as a useful marker for the activity of AS and untreated SLE.

Recovery of apparent diffusion coefficient after embolic stroke does not signify complete salvage of post-ischemic neuronal tissue

BACKGROUND AND PURPOSE

It has been shown in previous studies that recovery of apparent diffusion coefficient (ADC) of water is not necessarily associated with a reversal of tissue damage. We examined the relationships between temporal ADC change and histological outcome after embolic stroke in rat using an experimental MRI scanner.

SUBJECTS AND METHODS

Male Wistar rats underwent embolization of the right middle cerebral artery with autologous clot. ADC and relative cerebral blood flow (rCBF) were measured consecutively for 3 hours after embolization. The brains were prepared for histological examination.

RESULTS

Transient decline of ADC was observed during the initial 2 hours after embolization. In these areas, serial rCBF measurement revealed incomplete recovery. In some other areas, ADC decrease without rCBF recovery was observed during 3 hours postischemia. Histological examination revealed infarction in areas with persistent ADC decrease. Scattered neuronal death was noticeable in areas with a transient--in some areas less than 0.5 hour--ADC decrease.

CONCLUSION

Consecutive MRI analysis demonstrated postischemic transient ADC decrease in an embolic stroke model of rat. The normalization of ADC does not signify normalization of postischemic tissue, since the areas often evolve postischemic neuronal death at a later time.

A thiol proteinase inhibitor, E-64-d, corrects the abnormalities in concanavalin A cap formation and the lysosomal enzyme activity in leucocytes from patients with Chediak-Higashi syndrome by reversing the down-regulated protein kinase C activity

We have reported previously that the abnormally down-regulated protein kinase C (PKC) causes cellular dysfunction observed in natural killer (NK) cells, polymorphonuclear leucocytes (PMNs) and fibroblasts from beige mouse, an animal model of Chediak-Higashi syndrome (CHS). Here we show that the abnormal down-regulation of PKC activity also occurs in Epstein-Barr (EB) virus-transformed cell lines from CHS patients. When CHS cell lines were stimulated with concanavalin A (Con A) for 20 min, the membrane-bound PKC activity declined markedly, whereas that in control cell lines increased. We found that E-64-d, which protects PKC from calpain-mediated proteolysis, reversed the declined PKC activity and corrected the increased Con A cap formation to almost normal levels in CHS cell lines. We confirmed that the dysregulation of PKC activity also occurred in peripheral blood mononuclear leucocytes (PBMC) from CHS patients and that E-64-d corrected both the declined PKC activity and increased Con A cap formation. E-64-d also corrected the reduced lysosomal elastase and cathepsin G activity in CHS cell lines. In contrast, chelerythrin, a specific inhibitor of PKC, and C2-ceramide, which promotes PKC breakdown induced by calpain, increased Con A cap formation and inhibited both elastase and cathepsin G activity in normal cell lines. Moreover, we found that ceramide production in CHS cell lines increased significantly after Con A stimulation, which coincides with our previous observation in fibroblasts from CHS mice. These results suggest an association between ceramide-induced PKC down-regulation and the cellular dysfunctions in CHS.

Protein kinase C is involved in cardioprotective effects of ischemic preconditioning on infarct size and ventricular arrhythmia in rats in vivo

Protein kinase C (PKC) has been known to play an important role in ischemic preconditioning (IP). This study was designed to examine whether the translocation of PKC is associated with the cardioprotective effects of IP in vivo on infarct size and ventricular arrhythmias in a rat model. Using anesthetized rats, heart rate, systolic blood pressure, infarct size and ventricular arrhythmias during 45 min of coronary occlusion were measured. PKC activity was assayed in both the cytosolic and cell membrane fraction. Brief 3-min periods ofischemia followed by 10 min ofreperfusion were used to precondition the myocardium. Calphostin C was used to inhibit PKC. Infarct size was significantly reduced by IP (68.1 (2.5)%, mean (S.E.) vs. 45.2 (3.4)%, p < 0.01). The reduction in infarct size by IP was abolished by pretreatment with calphostin C. The total number of ventricular premature complex (VPC) during 45 min of coronary occlusion was reduced by IP (1474 (169) beats/45 min vs. 256 (82) beats/45 min, p < 0.05). The reduction the total number of VPC induced by IP was abolished by the administration of calphostin C before the episode of brief ischemia. The same tendency was observed in the duration of ventricular tachycardia and the incidence of ventricular fibrillation. PKC activity in the cell membrane fraction transiently increased immediately after IP (100 vs. 142%, p < 0.01) and returned to baseline 15 min after IP. Pretreatment with calphostin C prevented the translocation of PKC. The translocation of PKC plays an important role in the cardioprotective effect of IP on infarct size and ventricular arrhythmias in anesthetized rats.

Abnormal down-regulation of PKC is responsible for giant granule formation in fibroblasts from CHS (beige) mice--a thiol proteinase inhibitor, E-64-d, prevents giant granule formation in beige fibroblasts

We have previously reported that the abnormally rapid down-regulation of protein kinase C (PKC) activity is responsible for the cellular dysfunction in natural killer (NK) cells and polymorphonuclear leukocytes (PMNs) from Chediak-Higashi syndrome (beige) mice. In this report, we examined whether the down-regulation of PKC is associated with giant granule formation in fibroblasts from beige mice. In cultured beige fibroblasts, the membrane-bound PKC activity declined significantly after phorbol ester stimulation. We found that E-64-d, which is a thiol proteinase inhibitor and protects PKC from calpain-mediated proteolysis, reversed the declined PKC activity and prevented giant granule formation in beige fibroblasts. Moreover, E-64-d corrected the reduced lysosomal elastase and cathepsin G activity in beige fibroblasts. In contrast, specific PKC inhibitors, chelerythrin and calphostin C, promoted giant granule formation in normal fibroblasts. We also demonstrate that ceramide production is enhanced in beige fibroblasts and is involved in the rapid down-regulation of PKC. These results suggest that the accelerated breakdown of PKC observed in beige fibroblasts is caused by enhanced ceramide production and is also responsible for giant granule formation.

Interleukin 18 and interleukin 1beta production is decreased in HIV type 1-seropositive hemophiliacs but not in HIV type 1-seropositive nonhemophiliacs

In Japan, the proportion of hemophiliacs infected with human immunodeficiency virus type 1 (HIV-1) is 40%, whereas more than 90% are infected with hepatitis C virus (HCV). To evaluate the immunological status of hemophiliacs infected with HIV-1, we investigated the pattern of cytokine production in peripheral blood mononuclear cells (PBMCs) of HIV-1-seropositive and -seronegative hemophiliacs, HIV-1-seropositive non-hemophiliacs, and healthy individuals. The production of IL-18 and IL-1beta from PBMCs stimulated with Staphylococcus aureus Cowan strain 1 (SAC) in the HIV-1-seropositive hemophiliacs was significantly decreased in comparison with the other groups. On the other hand, IL-12 production in both HIV-1-seropositive groups was significantly lower than in HIV-1-seronegative groups. TNF-alpha and IL-6 production was similar among the four groups. In contrast, plasma levels of TGF-beta1 were increased in HIV-1-seropositive hemophiliacs, HIV-1-seropositive nonhemophiliacs, and HIV-1-seronegative hemophiliacs, with the highest levels being in HIV-1-seropositive hemophiliacs, suggesting that coinfection with HIV-1 and HCV increases the level of plasma TGF-beta in HIV-1-seropositive hemophiliacs. Treatment of PBMCs from healthy individuals with TGF-beta1 inhibited IL-18 and IL-1beta production without affecting IL-6, IL-10, or TNF-alpha production. Suppression of the expression of caspase 1 mRNA, which is known to be an IL-1beta-converting enzyme and which also cleaves the precursor of IL-18, was observed in the SAC-stimulated PBMCs from healthy individuals after treatment with TGF-beta1 and in the SAC-stimulated PBMCs from HIV-1-seropositive hemophiliacs, suggesting that the decreased production of IL-18 and IL-1beta in HIV-1-seropositive hemophiliacs may be related to the downregulation of caspase 1 mRNA induced by high levels of TGF-beta1 in plasma.

Reverse transcriptase (RT)-independent as well as RT-dependent HIV-1 replication exists in syncytia following cell fusion

We studied the role of reverse transcriptase (RT) in human immunodeficiency virus (HIV)-1 replication in syncytia following cell fusion. A chronically HIV-1-infected MOLT-4 (MOLT-4/IIIB) cells allow HIV-1 replication and induce syncytium formation between uninfected MOLT-4 cells. AZT (3'-azido-3'-deoxythymidine, 1 microM) inhibited neither HIV-1 replication in MOLT-4/IIIB cells nor the syncytium formation induced by concultivation of MOLT-4/IIIB cells with uninfected MOLT-4 cells. In the supernatant of the syncytium containing culture a remarkably higher titer of p24 antigen was produced than in that of MOLT/IIIB cell culture. AZT inhibited p24 antigen production by HIV-1 in the syncytia to levels to comparable to that in MOLT-4/IIIB cells which were treated with AZT. In addition, p24 production by HIV-1 in the syncytia formed by cocultivation of CL-2 cells, which are chronically infected with HIV-1 but lack functional RT, with uninfected MOLT-4 cells was not different from that in CL-2 cells alone. The results suggest that HIV-1 RT plays an important role in HIV-1 replication within the syncytia but an RT-independent replication process which is essential for syncytium formation also exists in the syncytia. These results indicate that not only RT inhibitors but also inhibitors of syncytium formation are essential for anti-HIV therapy.

HIV type 1 Tat protein inhibits interleukin 12 production by human peripheral blood mononuclear cells

HIV-1 Tat protein, which trans-activates HIV-1 expression, exerts many effects on host immune function. Meanwhile, PBMCs and pulmonary macrophages from HIV-1-infected patients produce only a small amount of IL-12, which plays an essential role in the development of helper T type 1 (Th1) cells, and in the generation of cytotoxic T lymphocytes. We examined the possibility that Tat suppresses IL-12 production by PBMCs from healthy donors. Tat significantly inhibited IL-12 production by human PBMCs stimulated with Staphylococcus aureus Cowan 1 strain (SAC) at concentrations between 5 and 40 ng/ml. Immunoabsorption by using polyclonal antibody to Tat abolished the suppression of the IL-12 production by Tat. Tat at the same concentrations did not affect IL-10, IL-6, or TNF-alpha production. Other HIV-1 proteins (Nef and gp120) did not influence IL-12 production. Tat also suppressed the expression of mRNA encoding the p40 chain of IL-12, whereas it did not affect the expression of mRNA encoding IL-10 and beta-actin. IL-12 production by monocytes, separated from PBMCs by the adhesion method, was also inhibited by Tat. These results suggest that Tat protein is one of the main causes of decreased IL-12 production by PBMCs (mostly by monocytes) from HIV-1-infected individuals.

Ceramide promotes calpain-mediated proteolysis of protein kinase C beta in murine polymorphonuclear leukocytes

Ceramide has been recognized as an important second messenger in intracellular signaling. We demonstrate here that ceramide promotes the down-regulation of protein kinase C (PKC) activity in phorbol ester-stimulated murine polymorphonuclear leukocytes (PMNs). As reported previously, treatment of PMNs with phorbol ester caused a translocation of PKC from the cytosolic to the membrane fractions. When PMNs were pretreated with cell-permeable ceramide analogue, C2-ceramide, the membrane-associated PKC activity was rapidly down-regulated by phorbol ester stimulation. E64-d, a potent inhibitor of calpain which proteolyzes PKC, eliminated the rapid down-regulation of PKC activity. By hydroxyapatite column chromatography and Western blotting, the predominant PKC isoform was PKC beta with a small amount of PKC alpha in murine PMNs. We found that ceramide strikingly promoted calpain-mediated proteolysis of PKC beta in vitro. Ceramide was also shown to inhibit [3H]phorbol 12,13-dibutyrate(PDBu) binding to PKC beta. Moreover, we show that ceramide stimulates PKC beta autophosphorylation. These results suggest that ceramide directly activates PKC beta and promotes calpain-mediated proteolysis in murine PMNs.

A simple and sensitive bioassay for the detection of human interleukin-18/interferon-gamma-inducing factor using human myelomonocytic KG-1 cells

Interleukin-18 (IL-18)/interferon-gamma-inducing factor (IGIF) is a novel cytokine which plays an important role in Th1 responses. Here we describe a simple, sensitive bioassay for human IL-18 using the human myelomonocytic cell line, KG-1, which produces IFN-gamma in response to human IL-18. IFN-gamma production induced by human IL-18 was completely blocked by an antibody against human IL-18. Human IL-18 could be measured in a concentration range from approximately 100 to 10,000 pg/ml, and intra- and inter-assay coefficient variations were both below 15%. It was possible to measure human IL-18 in human serum, cell lysate or culture supernatant by this bioassay. Thus, the human IL-18 bioassay can be expected to be useful in the investigation of the relationship between human IL-18 and various diseases or in analyzing the mechanisms of human IL-18 secretion from IL-18 producing cells.

Cloning and expression of five myb-related genes from rice seed

Three elements in the promoter of rice glutelin genes are important for their endosperm specific expression. One of these, an AACA motif, has been shown to be a negative regulator in non-seed tissues and has a similarity to the barley gibberellin responsive element recognized by MYB-like DNA binding proteins. A cDNA library constructed from immature rice seed was screened using two types of myb gene probes to isolate cDNA clones representing genes encoding MYB-like DNA binding proteins that may recognize the AACA motif in rice glutelin gene promoter. We obtained four cDNA clones encoding MYB-related proteins, Oryza sativa MYB (OSMYB) 1-4, using the maize C1 probe. Another myb-like clone, Osmyb5, was obtained by screening a rice seed cDNA library with probes designed to recognize the AACA-like binding domain in GAMYB and PHMYB3. RT-PCR was used to analyze Osmyb expression during rice seed development and their presence in other rice tissues, as it was not possible to detect these mRNAs by conventional Northern analysis. RT-PCR analysis showed that Osmyb2, Osmyb3 and Osmyb5 genes were expressed in all tissues examined. In seed, the mRNA levels of Osmyb1 and Osmyb4 genes reached a maximum at 14 days after flowering (DAF), suggesting that these genes may play a role in seed maturation. As Osmyb5 exhibits a high similarity to the regions in both GAMYB and PHMYB3, which can bind to the AACA motif, there is a possibility that the OSMYB5 protein may bind to the AACA motif of glutelin genes.

Interferon-gamma-inducing factor enhances T helper 1 cytokine production by stimulated human T cells: synergism with interleukin-12 for interferon-gamma production

The novel cytokine interferon-gamma-inducing factor (IGIF) augments natural killer (NK) cell activity in cultures of human peripheral blood mononuclear cells (PBMC), similarly to the structurally unrelated cytokine interleukin (IL)-12. IGIF has been found to enhance the production of interferon-gamma (IFN-gamma) and granulocyte/macrophage colony-stimulating factor (GM-CSF) while inhibiting the production of IL-10 in concanavalin A (Con A)-stimulated PBMC. In this study, when anti-CD3 monoclonal antibody (mAb)-stimulated human enriched T cells were exposed to IGIF, the cytokine dose-dependently enhanced the proliferation of the cells and this could be completely inhibited by a neutralizing antibody against IL-2 at lower concentrations of IGIF. Neutralizing antibody against IFN-gamma had only insignificant inhibitory effects on T cell proliferation at higher concentrations of IGIF. Enzyme-linked immunosorbent assays (ELISA) revealed that, like PBMC, T cells exposed to IGIF produced large amounts of IFN-gamma; however, changes in the production of IL-4 and IL-10 were minimal. IGIF, but not IL-12, significantly enhanced IL-2 and GM-CSF production in T cell cultures, as determined by CTLL-2 bioassay and ELISA, respectively; however, both IGIF and IL-12 enhanced IFN-gamma production by the T cells. When T cells were exposed to a combination of IGIF and IL-12, a synergistic effect was observed on the production of IFN-gamma, but not on production of IL-2 and GM-CSF. In conclusion, IGIF enhances T cell proliferation apparently through an IL-2-dependent pathway and enhances Th1 cytokine production in vitro and exhibits synergism when combined with IL-12 in terms of enhanced IFN-gamma production but not IL-2 and GM-CSF production. Based on structural and functional differences from any known cytokines, it was recently proposed that this cytokine be designated interleukin-18.

Cloning of the cDNA for human IFN-gamma-inducing factor, expression in Escherichia coli, and studies on the biologic activities of the protein

We have recently reported that a novel molecule, murine IFN-gamma-inducing factor (IGIF) produced by mouse liver cells, possesses potent biologic activities, including the induction of IFN-gamma production by spleen cells and the enhancement of NK cell cytotoxicity. In this paper, we report on the isolation of human IGIF cDNA clones from normal human liver cDNA libraries using murine IGIF cDNA as a probe. The amino acid sequence deduced from the human cDNA clones indicated a 193-amino acid precursor peptide and revealed 65% homology with that of murine IGIF. The amino acid sequence of IGIF also included an IL-1 signature-like sequence. Subsequently, the cloned cDNA was expressed in Escherichia coli, and preliminary studies on the biologic activities of the recombinant protein were performed. The recombinant human IGIF induced IFN-gamma production by mitogen-stimulated PBMC and enhanced NK cell cytotoxicity, in a manner similar to murine IGIF. In addition, recombinant human IGIF also augmented granulocyte-macrophage-CSF production and decreased IL-10 production, but had no effect on IL-4 production by Con A-stimulated PBMC. Based on these pleiotropic effects of IGIF, we propose that this novel cytokine be designated as IL-18.

Cloning of the cDNA for human IFN-gamma-inducing factor, expression in Escherichia coli, and studies on the biologic activities of the protein

We have recently reported that a novel molecule, murine IFN-gamma-inducing factor (IGIF) produced by mouse liver cells, possesses potent biologic activities, including the induction of IFN-gamma production by spleen cells and the enhancement of NK cell cytotoxicity. In this paper, we report on the isolation of human IGIF cDNA clones from normal human liver cDNA libraries using murine IGIF cDNA as a probe. The amino acid sequence deduced from the human cDNA clones indicated a 193-amino acid precursor peptide and revealed 65% homology with that of murine IGIF. The amino acid sequence of IGIF also included an IL-1 signature-like sequence. Subsequently, the cloned cDNA was expressed in Escherichia coli, and preliminary studies on the biologic activities of the recombinant protein were performed. The recombinant human IGIF induced IFN-gamma production by mitogen-stimulated PBMC and enhanced NK cell cytotoxicity, in a manner similar to murine IGIF. In addition, recombinant human IGIF also augmented granulocyte-macrophage-CSF production and decreased IL-10 production, but had no effect on IL-4 production by Con A-stimulated PBMC. Based on these pleiotropic effects of IGIF, we propose that this novel cytokine be designated as IL-18.

Characterization of common cis-regulatory elements responsible for the endosperm-specific expression of members of the rice glutelin multigene family

Glutelin is the most abundant storage protein in rice, which is expressed specifically in the endosperm of maturing seed. Glutelin is encoded by about 10 genes per haploid genome, which are clearly divided into two subfamilies (GluA and GluB). Most of them are coordinately expressed during seed maturation in spite of the remarkable divergence in the 5'-flanking regions between members of two subfamilies. In order to identify the common regulatory mechanisms responsible for the endosperm-specific expression, various cis-regulatory elements in the 5'-flanking region of the glutelin GluB-1 gene were characterized by studying the expression of chimeric genes that consisted of the sequentially deleted or mutagenized promoter and a beta-glucuronidase (GUS) reporter gene in transgenic tobacco seeds. The essential cis-regulatory elements governing the spatially and temporally specific expression of the glutelin gene expression were located within the first 245 bp of the promoter region of the GluB-1 gene from the site of initiation of transcription. The AACA motif between positions -73 and -61 common to all the six genes for glutelin sequenced to date and is repeated between positions -212 and -200 is implicated in the seed-specific expression. The GCN4 motif between positions -165 and -158 and between positions -96 and -92 that is conserved at homologous sites in all the members of glutelin gene family is also involved in the seed-specific regulation. However, both are required for the high level of seed-specific expression, because deletion of the region containing one set of both elements or substitution mutation of the AACA or GCN4 motif substantially reduced the activity. As a whole, our results suggest the combinatorial interaction of the elements in regulation of the glutelin gene expression.

[The influence of pregnancy and delivery on the climacteric symptoms]

This study was undertaken to investigate the influence of past pregnancy and delivery on the perimenopausal status in 144 women (48-52 years of age). Individual interviews to ascertain the personal profile, medical history, events at pregnancy, delivery and puerperium, and the kind and severity of climacteric symptoms were held. The subjects were divided into two groups by means of a simplified menopausal index (SMI): group A had climacteric symptoms (SMI > 50) and those in group B had mild symptoms (SMI < or = 50). The analysis of the principal components, and the correlation among the variables revealed that three factors--the impression and events at past pregnancies and deliveries, reproductive functions, and the psycho-character properties--had a significant influence on the status at the perimenopause, but the social-environmental factors appeared to have no significant influence on the severity of climacteric symptoms.

A novel costimulatory factor for gamma interferon induction found in the livers of mice causes endotoxic shock

Administration of monoclonal anti-CD3 antibody to mice treated with Propionibacterium acnes induced secretion of a high level of gamma interferon (IFN-gamma) into the circulation system, while it induced no significant release in untreated mice. In order to analyze this high-level induction of IFN-gamma in these bacterium-treated mice, we investigated the factors that might be involved. An activity that induces IFN-gamma in T cells was observed in the liver extracts of mice treated with P. acnes and subsequently challenged with lipopolysaccharide. Here, we purified an IFN-gamma-inducing factor from the liver extract to homogeneity and characterized it. Its molecular mass was 18 to 19 kDa, and its pI was 4.9. The amino acid sequence of the NH2-terminal portion was determined and shown to have no similarities to any protein in the EMBL, GenBank, and PIR data bases. The same molecule was also demonstrated in the serum factor that was previously reported to have an IFN-gamma-inducing activity and to have an apparent molecular mass of 75 kDa. Moreover, the activity of this serum factor was recovered in the fraction containing the 18- to 19-kDa protein under reducing conditions and was shown to have the same NH2-terminal amino acid sequence as that of the factor from the liver extract. In addition to the ability to induce IFN-gamma, this protein augmented T-cell proliferation and NK activity in the spleen cells. Thus, several of its biological activities were apparently similar to those of interleukin-12. These results indicated that this novel protein, which exhibited marked costimulatory activity on IFN-gamma production in vitro, was elevated vivo in response to P. acnes treatment. This factor, probably released from the producing cells by lipopolysaccharide stimuli, may be involved in the high-level induction of IFN-gamma in the P. acnes-treated mice.

[Method of DNA extraction and mecA, femA and PBP2' in multi-drug resistant bacterial strains]

Recently, it has become more important to establish rapid and reliable methods for identifying bacterial species and their drug resistances because of the high incidence of nosocomial infection caused by multi-drug resistant bacteria. At first, several enzymes were tested to evaluate the efficacy of DNA extraction. N-acetylmuramidase, lysozyme and achromopeptidase were most effective to extract DNA from E. faecalis, E. faecium and S. aureus, respectively. After achromopeptidase extraction, the mecA gene was amplified by polymerase chain reaction (PCR) in clinically isolated MRSA (95 strains), MSSA (66), MRSE (methicillin-resistant S. epidermidis, 37), MSSE (methicillin-sensitive S. epidermidis, 1), S haemolyticus(5), S.hominis(1) and others (Enterococcus, Pseudomonas, and Streptococcus, total 45). PCR products were analyzed by agarose gel electrophoresis. The positive rates were 95% (MRSA), 1.5% (MSSA), and 97% (MRSE). The mecA gene was also positive in 2/2 of methicillin-resistant S.haemolyticus and 2/3 of methicillin-sensitive S.haemolyticus and 1/1 of methicillin-resistant S.hominis. The mecA gene was not detected in 45 non-Staphylococcal strains. MecA and femA gene by PCR and PBP 2' by IRMA were further detected in newly isolated MRSA (20 strains), MSSA(20), MRSE(14), MSSE(1) and S.simulans(2). Complete correlation between MPIPC susceptibility and mecA were found. The femA gene was positive in 39/40 of S. aureus, and 0/14 of S.epidermidis, 2/3 of S.simulans. PBP2' were positive in 20/20 of MRSA, 0/20 of MSSA, 14/14 of MRSE, 0/1 of MSSE, 1/1 of methicillin-resistant S.simulans, and 0/2 of methicillin-sensitive S.simulans. In conclusion, diagnoses of MRSA by simultaneous detection of mecA and femA gene as well as PBP2' are similarly useful because of their specificity and rapidity.

The properties and mec A gene of the methicillin-resistant Staphylococcus aureus isolated in Fukushima Medical College Hospital

The 106 methicillin-resistant strains of Staphylococcus aureus (MRSA) isolated in Fukushima Medical College Hospital were examined for their properties and mecA gene. The strains produced four types of coagulase, of which type II was the most common, produced by 84 (79.2%). Beta-lactamase was produced by 58 (50%). Enterotoxins were produced by 45 (42.5%), most of which (39/106, 36.8%) were of type A. Thirty-four strains (32.1%) produced both enterotoxins and toxic shock syndrome toxin-1. All strains were susceptible to vancomycin and arbekacin, although they were mostly resistant to many other antibiotics. Using the polymerase chain reaction (PCR) technique, the mecA gene was detected in 57 (91.9%) of the 62 strains used. In addition, one of the 42 methicillin-susceptible strains isolated had the mecA gene. These results indicate that detection of the mecA gene by the PCR technique is a rapid and accurate way to identify methicillin resistance.

The genotoxicity of UVA irradiation in Drosophila melanogaster and the synergistic action of 8-methoxypsoralen and UVA

To study the genotoxicity of near-ultraviolet light (UVA) on a whole body, Drosophila melanogaster larvae were irradiated with UVA and the emerging flies were examined for the mutant wing spot formation. The genotoxicity of UVA was also assayed with the in vivo DNA-repair test using males with repair-deficiency at the mei-9 and mei-41 locus and the matching repair-proficient females. Third-instar larvae were placed in a plastic Petri dish, which was covered with soft glass, and irradiated with black light at 4-5 W/m2. This irradiation resulted in an increase in mutant wing-hair spots. After a 15 h irradiation (approximately 240 kJ/m2), the mutant clone frequencies found in the adult flies (spots/wing) were: 1.68 for the small single spots, 0.38 for the large single spots and 0.11 for the twin spots, while at zero time they were 0.68, 0.06 and 0.02 respectively. On the other hand, the UVA irradiation was negative in the in vivo DNA-repair test, indicating that the UVA-induced DNA lesion may not be subject to repair by the mei-9 and mei-41 functions. The presence of 8-methoxypsoralen (8-MOP) during the irradiation remarkably enhanced somatic mutations, and showed a strong DNA-damaging effect in the repair test. For example, a 15 h UVA irradiation with 26.7 microM 8-MOP resulted in a 14-fold increase in the number of twin spots per wing as compared with the frequency obtained on treatment with UVA alone. Treatment of the larvae with 8-MOP alone gave no mutant clones or DNA damage. A high frequency in twin spot formation was also observed in this UVA + 8-MOP treatment, indicating that extensive chromosomal recombinations took place in the somatic cells.

Thiol proteinase inhibitors reverse the increased protein kinase C down-regulation and concanavalin A cap formation in polymorphonuclear leukocytes from Chediak-Higashi syndrome (beige) mouse

Protein kinase C (PKC) plays an essential role in intracellular signal transduction for various cell functions, including concanavalin A (Con A)-induced cap formation. This enzyme is known to be proteolysed by calpain, which is a Ca2(+)-dependent thiol proteinase. As reported previously, in polymorphonuclear leukocytes (PMNs) from beige mouse, the model of Chediak-Higashi syndrome, Con A-induced cap formation significantly increased compared with that in normal mouse. However, after pretreatment of beige PMNs with the thiol proteinase inhibitors leupeptin or E-64, the capping decreased to normal levels. Meanwhile, Con A-induced the translocation of PKC from the cytosolic to membrane fraction within 5 min in both mice, which is essential to the activation of this enzyme. However, after the translocation, an abnormal rapid decline in membrane-bound PKC activity was noted in beige mouse PMNs. Both leupeptin and E-64 also corrected the rapid decline in PKC activity observed in the beige mouse. These findings suggest that the normalization of Con A cap formation in beige mouse PMNs by the thiol proteinase inhibitors is associated with the correction of abnormality in PKC activity.

Protein kinase C inhibitors enhance concanavalin A cap formation in polymorphonuclear leukocytes

The potent protein kinase C (PKC) inhibitors, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7) and staurosporine, significantly enhanced concanavalin A (Con A)-induced cap formation in polymorphonuclear leukocytes (PMNs) from C57BL/6 mice after pretreatment for 30 min at concentrations of 10 microM and 1 nM, respectively. However, neither 10 microM of N-(2-aminoethyl)-5-isoquinolinesulfonamide dihydrochloride (H-9) nor N-(2-guanidinoethyl)-5-isoquinolinesulfonamide hydrochloride (HA1004), which inhibit cyclic nucleotide-dependent protein kinases more effectively than other kinases, affected the capping. Meanwhile, treatment of PMNs with Con A induced the translocation of PKC from the cytosol to the membrane fraction within 5 min, which is considered to be important for the activation of this enzyme. When cells were pretreated with H-7 or staurosporine for 30 min at the concentrations that enhanced the capping, both the cytosolic and the membrane-bound PKC activity was inhibited during the further incubation with Con A. These results suggest that PKC may play an important role in the regulation of Con A-induced cap formation in PMNs.

Possible involvement of microfilaments in protein kinase C translocation

We investigated the role of microfilaments in stimulus-induced translocation of protein kinase C (PKC) in polymorphonuclear leukocytes (PMNs) from C57BL/6 mice. Cytochalasin B and dihydrocytochalasin B almost completely inhibited PKC translocation induced by either TPA or Ca2+ ionophore after pretreatment of cells for 30 min. In addition, ML-9, a potent inhibitor of Ca2+/calmodulin-dependent myosin light chain kinase which regulate microfilament contraction, and a calmodulin antagonist W-7, also inhibited PKC translocation. These findings suggest the possibility that microfilaments are involved in the translocation of PKC.

The thiol proteinase inhibitors improve the abnormal rapid down-regulation of protein kinase C and the impaired natural killer cell activity in (Chediak-Higashi syndrome) beige mouse

Protein kinase C (PKC) is essential in intracellular signal transduction for various cell functions including natural killer (NK) cell activity. This enzyme is hydrolysed by calpain, which is Ca2+-dependent thiol proteinase. We showed here that in NK activity-deficient beige (bg/bg) mouse, the model of Chediak-Higashi syndrome, the translocated membrane-bound PKC activity declined rapidly in NK cell-enriched lymphocytes after TPA stimulation. However, the rapid decline was abolished by the pretreatment of cells with leupeptin (a thiol and serine proteinase inhibitor) or E64 (a thiol proteinase inhibitor). Furthermore, these reagents improved the impaired NK cell activity in beige mouse whereas they did not affect NK cell activity in C57BL/6 (+/+) and the heterozygous (+/bg) mice. Meanwhile, TPA stimulation induced only low levels in NK cytotoxic factors (NKCF) release from beige NK cells, but these reagents augmented the lowered NKCF release. These results suggest that the improvement of impaired NK cell activity in beige mouse by the thiol proteinase inhibitors may be due to the elimination of abnormal rapid down-regulation of PKC, resulting in the augmentation of the lowered PKC activity.

Tumor necrosis factor enhances replication of human immunodeficiency virus (HIV) in vitro

The effect of tumor necrosis factor (TNF) on the replication of human immunodeficiency virus type 1 (HIV-1) was investigated in several T4 lymphocyte cell lines. TNF markedly enhanced the cytopathogenicity of HIV-1, virion-associated reverse transcriptase (RT) activity in the cell culture supernatant, and viral antigen expression in MOLT-4 cells as early as 3 days after HIV-1 infection. A slight increase in RT activity was also observed in the supernatant of H9 cell cultures exposed to TNF. However, TNF did not increase either RT activity in MT-4 cell supernatants or viral antigen expression in HUT-78 cells. Thus, TNF is able to stimulate the replication of HIV-1 in de novo infected T4 cells although not all T4 cells seem to be sensitive to this stimulatory effect.

Inhibition of natural killer cell-mediated cytotoxicity by ML-9, a selective inhibitor of myosin light chain kinase

To investigate the role of microfilaments in natural killer (NK) cell-mediated cytotoxicity, general microfilament inhibitors, cytochalasins B,D and dihydrocytochalasin B, and a selective inhibitor of myosin light chain kinase (MLCK) which regulates microfilament contraction, i.e. 1-(5-chloronaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine hydrochloride (ML-9) were examined in an NK assay system. ML-9 inhibited NK cell activity in a dose-dependent manner without affecting target cell binding, whereas cytochalasins suppressed the binding. The dextran suspension method revealed that ML-9 inhibits the programming for the lysis stage of the lytic process. In the single cell assay, the addition of ML-9 after target cell binding had occurred inhibited the lysis of bound target cells, whereas the addition of cytochalasins in a similar manner did not affect it. Thus, these results suggest the possibility that microfilament contraction is involved in the lytic mechanism of NK cell-mediated cytolysis. However, the mechanism whereby cytochalasins inhibit target cell binding remains unclear.

Mechanism of inhibitory effect of glycyrrhizin on replication of human immunodeficiency virus (HIV)

Glycyrrhizin (GL) achieved a dose-dependent inhibition of the replication of human immunodeficiency virus type 1 (HIV-1) in MOLT-4 (clone No. 8) cells within the concentration range of 0.075 to 0.6 mM. Within this concentration range, GL also effected a dose-dependent reduction in the protein kinase C (PKC) activity of MOLT-4 (clone No. 8) cells. A well-known PKC inhibitor, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7), also proved inhibitory to HIV-1 replication in MOLT-4 (clone No. 8) cells. PKC inhibition may thus be considered as one of the mechanisms by which GL inhibits HIV-1 replication. In addition, GL may also owe its anti-HIV-1 activity, at least in part, to an interference with virus-cell binding, since the compound at 1.2 mM partially inhibited the adsorption of radiolabeled HIV-1 particles to MT-4 cells. At this concentration GL also suppressed giant cell formation induced by co-culturing MOLT-4 (clone No. 8) cells with MOLT-4/HTLV-IIIB cells, whereas the PKC inhibitor H-7 failed to do so.

Rapid down-regulation of protein kinase C in (Chediak-Higashi syndrome) beige mouse by phorbol ester

Protein kinase C(PKC) activity in macrophages and polymorphonuclear leukocytes was assayed in beige mouse, the model of Chediak-Higashi syndrome, control C57BL/6 and the heterozygous (+/bg) mice. Regarding enzyme activity in the cytosolic and membrane fractions of these cells, there was no difference between beige mouse and the control. After short-term activation by TPA, the translocated membrane-bound PKC activity in beige mouse decreased rapidly compared with that in control mouse. However, the cytosolic PKC activity decreased at just the same pace as the control. The change in [3H] PDBu binding paralleled the changes in PKC activity. An increase in Ca2+/phospholipid-independent protein kinase by TPA was notable in the membrane fraction of beige mouse. The increase in the kinase activity was abolished and the PKC activity recovered to normal level by the addition of calpain inhibitor, leupeptin, to the incubation of cells along with TPA. Therefore, these findings suggest that a rapid decrease in membrane-bound PKC activity in beige mouse by TPA stimulation is associated with calpain.

Low-density lipoprotein oxidized by polymorphonuclear leukocytes inhibits natural killer cell activity

We studied the effect of low-density lipoprotein (LDL) oxidized by opsonized zymosan-stimulated polymorphonuclear leukocytes (PMN) on natural killer (NK) cell activity. Oxidized LDL inhibited NK cell activity in a dose-dependent manner, whereas normal LDL left it unaffected. However, oxidized LDL did not inhibit antibody-dependent cell-mediated cytotoxicity (ADCC). Moreover, a positive correlation was observed between the amount of thiobarbituric acid-reacting substances (TBARS) on the sample of oxidized LDL and the degree of inhibition of NK cell activity. We also showed that oxidized LDL suppressed the binding capacity of purified large granular lymphocytes (LGL) to target cells without changing the lytic activity. These results therefore suggest that activated PMN can modulate NK cell activity by oxidizing LDL.

Modulation of protein kinase C activity during inhibition of tumor cell growth by IFN-beta and -gamma

We investigated the effects of human interferon(IFN)-beta and -gamma on protein kinase C activity in human HEp-2 and KHm-14 tumor cells during IFN-induced inhibition of cell growth. Cytosolic protein kinase C activity in both cell lines was strikingly decreased following treatment with either IFN-beta or -gamma. In the particulate fraction, IFN-gamma decreased protein kinase C activity within 1 hr but it reappeared after 24 hr, whereas IFN-beta decreased the activity during the inhibition of cell growth. Furthermore, phorbol-12,13-dibutyrate(PDBu)-binding activity was altered in parallel with the changes in protein kinase C activity induced by the IFNs. In summary, we showed that IFN-beta and -gamma cause long-term modulation of protein kinase C activity in these cultured tumor cells.

A potent inhibitor of protein kinase C inhibits natural killer activity

A potent inhibitor of protein kinase C(PKC), 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7), dose-dependently inhibited natural killer (NK) activity in large granular lymphocytes (LGL) pretreated at 37 degrees C for 30 min. However, neither N-(2-aminoethyl)-5-isoquinolinesulfonamide dihydrochloride (H-9), which inhibits more effectively cyclic nucleotide-dependent protein kinases than other kinases, nor N-(2-guanidinoethyl)-5-isoquinolinesulfonamide hydrochloride (HA1004), which was used as a control for H-7, reduced NK activity. The inhibitor effect of H-7 was not due to changes in effector cell viability or target cell binding. We also found that H-7 suppresses PKC activity in both the cytosol and membrane fractions of LGL. From these findings, PKC is considered to play an essential role in the lytic mechanism of NK cell-mediated cytolysis.

Synergistic antiproliferative effect of interferon-beta in combination with bleomycin or neocarzinostatin on HeLa cells in culture: additive effect when combined with adriamycin or mitomycin C

Human fibroblast interferon (IFN)-beta was administered in combination with the free radical-generating antiproliferative agents bleomycin (BLM), neocarzinostatin (NCS), adriamycin (ADM), and mitomycin C (MMC) to HeLa cells in culture. IFN showed a true synergistic antiproliferative activity in the presence of BLM or NCS. These effects were observed regardless of the ratio of IFN to BLM or NCS concentrations. However, the effect of IFN in the presence of ADM or MMC was additive. The possibility that IFN-beta potentiates the antiproliferative effects of these free radical-generating agents in a different manner is also discussed.