Phagocytosis plays a dual role in activating dendritic cells; digestive production of active Toll-like receptor ligands and cooperation with Toll-like receptor signaling.

Phagocytosis is an initial step in innate immunity, which is also stimulated by signals via Toll-like receptors (TLRs); however, the cooperation of phagocytosis with signals through TLRs to establish acquired immunity is unknown. We found that phagocytosis is an essential process to induce an immune reaction against an insoluble TLR ligand. Cell-wall skeleton prepared from Mycobacterium bovis BCG (BCG-CWS), an insoluble TLR2 ligand, activated and matured murine splenic dendritic cell (DC) line BC-1 as well as a soluble TLR2 ligand, Pam3CSK4. Surprisingly, BC-1 maturation with BCG-CWS was completely suppressed by inhibiting phagocytosis, while that with Pam3CSK4 was not affected. Moreover, BCGCWS induced intense delayed-type hypersensitivity (DTH) reactions against mitomycin C-inactivated Lewis lung carcinoma cells but Pam3CSK4 did not. These results suggested that the phagocytosis process enables the insoluble TLR2 ligand to activate DCs via TLR2 comparable to a soluble TLR2 ligand in vitro, and stimulating TLR2 alone is not sufficient to establish T cell-mediated immunity in vivo. It is therefore conceivable that the process of phagocytosis induces additional effects on TLR2-stimulated DCs to activate cellmediated immunity in vivo.

Immune response against cell-wall skeleton of Mycobacterium bovis BCG at the inoculation site and peripheral lymphoid organs.

We reported in the previous paper that highly purified cell-wall skeleton of M. bovis BCG (SMP-105) eliminated lymph node metastases and primary implanted tumor, presumably by generating tumor immunity, employing guinea pigs. In this paper, we investigated the immune reactions to elucidate the mechanisms of antitumor activity. Twenty-four hours after intradermal injection, inflammatory cells were seen migrating to the inoculation site. Massive infiltrations of lymphocytes were observed on day 7, when a large amount of SMP-105 was still observed in the dermis. Several chemokines attracting neutrophils and monocytes, detected by TaqMan RT-PCR, were induced rapidly and declined 72 h post-injection, but most increased again on day 7, consistent with the pathological findings of lymphocyte infiltration. Activation of lymph node cells was investigated using mice. Upon stimulation by SMP-105 in vitro, the draining lymph node cells collected from mice treated with SMP-105 produced interferon-γ (IFN-γ), whereas, lymph node cells did not release IFN-γ when prepared from mice treated with OK-432. This evidence prompted us to assume that SMP-105 functioned as T cell antigens. Intracellular cytokine analysis demonstrated that IFN-γ was mainly attributable to CD4-CD8+αßT and CD4-CD8-αßT cells. In conclusion, oil-in-water emulsion of SMP-105 resided for a long time at the inoculation site and activated T cells, probably recognizing SMP-105 itself. The strong tumor eliminating activity of SMP-105 may be explained by the boost of generating tumor immunity via positive feed-back from T cells reacting to it, and CD4-CD8+αßT and CD4-CD8-αßT cells may distinguish SMP-105 from other synthetic adjuvants.

Injection of cell-wall skeleton of Mycobacterium bovis BCG draining to a sentinel lymph node eliminates both lymph node metastases and the primary transplanted tumor.

Based on recent developments in innate immunity, we focused on a microbial immunostimulator for cancer immunotherapy. If innate immunity is properly activated, tumor antigens distributed endogenously in cancer patients will be exploited to activate tumor immunity. We chose the cell-wall skeleton of M. bovis BCG (BCGCWS) and investigated the potential of monotherapy without exogenous tumor antigens. We used strain 2 guinea pigs bearing syngenic line 10 hepatoma, which is an excellent disease model of spontaneous lymph node metastasis, and examined the tumor-eradicating activity of highly purified BCG-CWS (SMP-105), excluding the effect of local inflammation on tumor growth. SMP-105 eliminated both established metastases and the implanted tumor, when injected into different but not distant sites from the tumor, whereas, when injected into the opposite side, neither metastases nor the primary tumor was eradicated. SMP-105 was observed in the draining lymph node engulfed by phagocytes, presumably macrophages or dendritic cells, but was not detected in distant lymph nodes or the spleen. It took about 2 weeks until the tumor-eliminating effect was observed. Taken together it is considered that macrophages or dendritic cells were activated by SMP-105 and encountered tumor cells in the sentinel lymph node to generate tumor immunity during the lag time. In conclusion, we suggested the potential of mono-therapy with a strong immunostimulator and that SMP-105 is a most promising agent for cancer immunotherapy. Separate injection from tumor draining to a sentinel lymph node using classical guinea pig models will be a useful method for investigating immunostimulators.

Two receptor theory in innate immune activation: studies on the receptors for bacillus Culmet Guillen-cell wall skeleton.

Activation of the innate immune system is a prerequisite for the maturation of dendritic cells (DC) and macrophages (Mphi) followed by clonal expansion of the lymphocytes, targeting cells expressing "non-self' antigens. Microbes usually have a component competent to activate DC/Mphi for antigen presentation. This component has been called adjuvant, but recently renamed "pathogen-associated molecular pattern" (PAMP) or modulin based on its molecular identification. Here, we propose the hypothesis that DC/Mphi express two sorts of receptors for PAMP, whose signaling pathways lead to a sufficient antigen (Ag)-presenting state. In bacterial infection, a Toll-like receptor (TLR) and an uptake receptor participate in DC maturation and Mphi activation. Likewise, with a number of viruses, two of the receptors, with short consensus repeats (SCR), immunoglobulin-like domains or chemokine receptor-like motifs etc. induce functional modulation of DC/Mphi. In immune therapy for cancer, primary activation of the innate system would be essential for tumor Ag-specific T cell augmentation. Cancer cells express tumor-associated Ag but barely co-express PAMP, which situation does not allow for the activation of innate immune responses. Supplementing tumor-associated Ag with PAMP may be an effective therapy for patients with cancer. Here, we discuss the possibility of an innate immune therapy for cancer with reference to bacillus Culmet Guillen cell-wall skeleton (BCG-CWS).

Interferon gamma-producing ability in blood lymphocytes of patients with lung cancer through activation of the innate immune system by BCG cell wall skeleton.

An in vitro assay system was developed to assess the potency of the human innate immune system by measurement of IL-12, IL-18, IL-10 and IFNgamma in the supernatants of bacillus Calmette-Guerin cell wall skeleton (BCG-CWS)-stimulated blood samples. BCG-CWS is a ligand for Toll-like receptor (TLR) 2 and 4, and activates monocytes to macrophages (Mphi), and immature dendritic cells to mature antigen-presenting cells (APC). This system was found to allow the discrimination of immune suppressive states in patients with lung cancer from normal immune states in light of the cytokine profile. The following results were deduced from analyses of BCG-CWS-stimulated blood samples of lung cancer patients with reference to normal subjects. (1) The levels of production of IFNgamma and IL-10 by lymphocytes were decreased. (2) IL-12 p40 production by monocytes/Mphi was upregulated, while that of IL-10 was downregulated. (3) IL-18 was detected in all patients in a range similar to normal subjects. (4) Responses of lymphocytes to IL-2 and IL- 18 in terms of IFNgamma production were diminished. (5) The upregulated IL-12 levels were recovered to within the normal range in most patients after tumor resection. (6) Male patients showed more severe suppression of IL-12/IL-18-mediated IFNgamma production than female patients. Thus, the lesser IFNgamma production observed in patients' blood with high IL-12 p40 levels in response to BCG-CWS may reflect the production of p40 dimers or IL-23 instead of p70, or the presence of some unknown pathways to prohibit the interface between the innate and acquired immune systems. BCG-CWS-mediated Toll signaling may participate in IFNgamma induction for lymphocytes through Mphi/APC IL-12/I-18 modulation.

Development of immunoadjuvants for immunotherapy of cancer.

Previously, we have reported that cell-wall skeleton (CWS) fraction was the major adjuvant-active principle of mycobacterial cells which were used in Freund's complete adjuvant (FCA). We have described the biochemical and immunological properties of CWS of mycobacteria and related bacteria, especially the CWS of Mycobacterium bovis BCG strain (BCG-CWS) in detail. The effectiveness of BCG-CWS for the cancer immunotherapy in patients was shown in several clinical trials. On the action mechanism of BCG-CWS on host immune cells, we have suggested that dendritic cells and macrophages express two sorts of receptors, Toll-like receptors, TLR-2 and TLR-4, and a putative binding receptor for BCG-CWS, whose signaling pathways lead to a sufficient antigen-presenting state in the activation of the innate immune system. We have also reported the usefulness of synthetic immunoadjuvants such as muramyldipeptide (MDP) derivatives, trehalose-dimycolates (TDM) and DNA fraction for the application for the cancer and infectious diseases in experimental systems and cancer patients.

Effect of Topically Applied Iganidipine Dihydrochloride, a Novel Ca(2+) Antagonist, on Optic Nerve Head Circulation in Rabbits.

Purpose: We studied the effect of topically applied iganidipine dihydrochloride, a novel water-soluble calcium channel blocker on the blood flow of optic nerve head (ONH), intraocular pressure, and blood pressure in rabbits.Methods: (1) 0.1% iganidipine (20 &mgr;l) was instilled into a normal eye. The change in blood flow in the ONH was measured using a hydrogen gas clearance flowmeter. (2) Iganidipine (0.0001%-0.1%) was instilled into a circulation-disordered eye before or after the intravitreal injection of endothelin-1, and change in the blood flow in the ONH was measured. (3) Changes in intraocular pressure and blood pressure after instillation of 0.1% iganidipine were measured. In all experiments, physiological saline was instilled in each contralateral eye as a control.Results: (1) Instillation of iganidipine significantly increased the blood flow in the ONH by 40% at 45 minutes after instillation. (2) Pre-instillation of 0.01 and 0.1% iganidipine almost completely inhibited the decrease of blood flow in the ONH in the circulation-disordered model. The decrease of blood flow in the ONH was corrected with post-instillation of 0.1% iganidipine. These effects were continuous. (3) Instillation of 0.1% iganidipine did not change either intraocular pressure or blood pressure.Conclusion: It was shown that instillation of iganidipine continuously increased and maintained the blood flow in the ONH in normal and circulation-disordered rabbit eye models.

Cellular and humoral adjuvant activity of lectins isolated from Korean mistletoe (Viscum album colaratum).

The adjuvant effect of lectins (KML-C) isolated from Korean mistletoe (Viscum album coloratum) on induction of humoral and cellular immune responses against keyhole limpet hemocyanine (KLH) was examined. When mice were immunized subcutaneously (s.c.) with KLH (20 micrograms/mouse) admixed with or without 50 ng/mouse of KML-C (KLH + KML-C), mice immunized with KLH + KML-C showed significantly higher antibody titers against KLH than those immunized with KLH alone, showing the highest titer 5 weeks after immunization. Furthermore, boost immunization with KLH + KML-C at 2-week interval elicited much higher activity than single immunization to enhance antibody responses against KLH. The assay for determining isotypes of antibodies revealed that KML-C augmented KLH-specific antibody titers of IgG1, IgG2a and IgG2b. The culture supernatants obtained from the splenocytes of mice treated with KLH + KML-C also showed a higher level of both KLH-specific Th-1 (IL-2 and IFN-gamma) and Th-2 type cytokine (IL-4). In an in vitro analysis of T lymphocyte proliferation to KLH on week 4, the splenocytes of mice treated with KLH + KML-C showed a significantly higher proliferating activity than those treated with KLH alone. In addition, mice immunized twice with KLH + KML-C and followed by intrafootpad (i.f.) injection of KLH (50 micrograms/site) 14 weeks after the primary immunization induced a higher delayed-type hypersensitivity (DTH) reaction than mice treated with KLH alone. These results suggest that KML-C is a potent immunoadjuvant to enhance cellular and humoral immune responses.

Effect of topically applied iganidipine dihydrochloride, a novel calcium antagonist, on optic nerve head circulation in rabbits.

PURPOSE: To study the effect of topically applied iganidipine dihydrochloride (iganidipine), a novel water-soluble calcium channel blocker, on blood flow in the optic nerve head (ONH), intraocular pressure, and systemic blood pressure in rabbits. METHODS: After 0.1% iganidipine (20 microL) was instilled into normal eyes, the change in ONH blood flow was measured using a hydrogen gas clearance flowmeter. Iganidipine (0.0001% to 0.1%) was instilled into eyes with impaired ocular circulation before or after the intravitreal injection of endothelin-1, and the change in ONH blood flow was measured. Changes in intraocular pressure and blood pressure after instillation of 0.1% iganidipine were measured. In all experiments, physiological saline was instilled into the contralateral eye as a control. RESULTS: Iganidipine significantly increased the ONH blood flow in normal eyes with the maximum increment of 31.7% at 45 minutes after instillation. Preinstillation of 0.01% and 0.1% iganidipine significantly inhibited the decrease in ONH blood flow in the eyes with impaired circulation. Moreover, ONH blood flow recovered with postinstillation of 0.1% iganidipine. These effects were persistent. Instillation of 0.1% iganidipine did not change either the intraocular pressure or the blood pressure. CONCLUSION: The instillation of iganidipine persistently increased and maintained the ONH blood flow in rabbit eyes with normal and impaired ocular circulation.

Maturation of human dendritic cells by cell wall skeleton of Mycobacterium bovis bacillus Calmette-Guérin: involvement of toll-like receptors.

The constituents of mycobacteria are an effective immune adjuvant, as observed with complete Freund's adjuvant. In this study, we demonstrated that the cell wall skeleton of Mycobacterium bovis bacillus Calmette-Guérin (BCG-CWS), a purified noninfectious material consisting of peptidoglycan, arabinogalactan, and mycolic acids, induces maturation of human dendritic cells (DC). Surface expression of CD40, CD80, CD83, and CD86 was increased by BCG-CWS on human immature DC, and the effect was similar to those of interleukin-1beta (IL-1beta), tumor necrosis factor alpha (TNF-alpha), heat-killed BCG, and viable BCG. BCG-CWS induced the secretion of TNF-alpha, IL-6, and IL-12 p40. CD83 expression was increased by a soluble factor secreted from BCG-CWS-treated DC and was completely inhibited by monoclonal antibodies against TNF-alpha. BCG-CWS-treated DC stimulated extensive allogeneic mixed lymphocyte reactions. The level of TNF-alpha secreted through BCG-CWS was partially suppressed in murine macrophages with no Toll-like receptor 2 (TLR 2) or TLR4 and was completely lost in TLR2 and TLR4 double-deficient macrophages. These results suggest that the BCG-CWS induces TNF-alpha secretion from DC via TLR2 and TLR4 and that the secreted TNF-alpha induces the maturation of DC per se.

Novel mutations in the myocilin gene in Japanese glaucoma patients.

Myocilin is a gene responsible for juvenile onset primary open angle glaucoma (POAG) mapped as the GLC1A locus and, many mutations have been reported worldwide. Some mutations were found not only in patients with juvenile onset POAG, but also in patients with late onset POAG and in patients with normal tension glaucoma. To investigate the mutation prevalence in Japan, we performed a mutation analysis in 140 unrelated Japanese patients. We have identified the 10 sequence variants, of which four were highly probable for disease-causing mutations (Arg46ter, Arg158Gln, Ile360Asn, and Ala363Thr), and six polymorphisms (Gln19His, Arg76Lys, Asp208Glu, Val439Val, Arg470His, and Ala488Ala). Thus, myocilin mutations were found at the rate of 4/140 (2.9%) probands, similar to previous reports with other ethnic populations.

[Effect of topically applied iganidipine dihydrochloride, a novel Ca2+ antagonist, on optic nerve head circulation in rabbits].

PURPOSE: We studied the effect of topically applied iganidipine dihydrochloride, a novel water-soluble calcium channel blocker on the blood flow of optic nerve head (ONH), intraocular pressure, and blood pressure in rabbits. METHODS: 1. 0.1% iganidipine (20 microliters) was instilled into a normal eye. The change in blood flow in the ONH was measured using a hydrogen gas clearance flowmeter. 2. Iganidipine (0.0001%-0.1%) was instilled into a circulation-disordered eye before or after the intravitreal injection of endothelin-1, and change in the blood flow in the ONH was measured. 3. Changes in intraocular pressure and blood pressure after instillation of 0.1% iganidipine were measured. In all experiments, physiological saline was instilled in each contralateral eye as a control. RESULTS: 1. Instillation of iganidipine significantly increased the blood flow in the ONH by 40% at 45 minutes after instillation. 2. Pre-instillation of 0.01 and 0.1% iganidipine almost completely inhibited the decrease of blood flow in the ONH in the circulation-disordered model. The decrease of blood flow in the ONH was corrected with post-instillation of 0.1% iganidipine. These effects were continuous. 3. Instillation of 0.1% iganidipine did not change either intraocular pressure or blood pressure. CONCLUSION: It was shown that instillation of iganidipine continuously increased and maintained the blood flow in the ONH in normal and circulation-disordered rabbit eye models.

Effect of the consumption of ethanol on the microcirculation of the human optic nerve head in the acute phase

Purpose: The effect of the consumption of ethanol on the circulation of the optic nerve head (ONH) in the human eye in the acute phase and its mechanism were studied.Methods: Eleven volunteers drank a bottle of beer (633 mL) with or without ethanol (29.5 g). Normalized blur (NB), a quantitative index of blood flow velocity, was measured in the temporal site of the ONH. NB, blood pressure (BP) and pulse rate (PR) were measured before, immediately after, and every 15 minutes for 90 minutes after consumption. Intraocular pressure (IOP) and plasma ethanol concentration were measured before, and 30 and 90 minutes after consumption. Genotyping of the aldehyde dehydrogenase (ALDH) 2 gene was also performed.Results: NB in the ONH increased significantly from 15 to 45 minutes after consumption of ethanol and the maximum increase was 14% at 15 minutes. IOP was lowered at 90 minutes after consumption, but it was not significant. Mean BP was lowered significantly after 60 minutes. PR and ocular perfusion pressure did not change. A significant correlation was found between plasma ethanol concentration at 30 minutes and maximum NB. NB in the ALDH 2-deficient group was significantly larger from 15 to 45 minutes after consumption than in the proficient group.Conclusions: It appeared that the consumption of ethanol can increase the blood flow in the human ONH in the acute phase through decreased resistance in blood vessels induced by acetaldehyde, a metabolite of ethanol.

Innate immune therapy for cancer. Screen for molecules capable of activating the innate immune system.

Tumor cells usually express antigens which are distinguishable from normal "self" antigens and are thereby recognized by the host immune system. However, the host immune system barely responds to tumors in patients. Supplementation with adjuvant (such as BCG-CWS) in patients with cancer contributes to regression of intrinsically growing cancer. The adjuvant targets antigen-presenting cells, i.e. innate immunity, but not lymphocytes, and promotes up-regulation of MHC, co-stimulators and initial cytokines in antigen-presenting cells. We hypothesized that the role of the adjuvant is to provide conditions suitable for antigen-presentation where antigens are available and the lack of adjuvant-induced priming of antigen-presenting cells results in unresponsiveness to tumor antigens. Here, we report innate immune therapy applicable to cancer patients by supplementation with adjuvants for induction of potent immune responses against tumors.

Evaluation of the circulation in the retina, peripapillary choroid and optic disk in normal-tension glaucoma.

Computerized image analysis, including fluorescein angiography, was used to evaluate the retinal, choroidal and optic disk blood flow in 16 patients with normal-tension glaucoma (NTG) and to correlate this measurement with visual fields, retinal vessel width, optic disk pallor and blood pressure (BP). The angle of the ascending slope of the fluorescein dye curve was measured as an index of blood flow from the densitometric and time curves of the fluorescein angiograms in the optic disk, peripapillary choroid, retinal artery and vein for each quadrant. While the ascending slope as well as the retinal vessel width were most reduced in the inferior and nasal regions, the mean threshold was lowest in the superior and nasal quadrants. There were positive significant correlations between artery width and threshold value, between angles of slopes and pallor. In addition, systolic BP had a negative correlation with pallor, and diastolic BP had a positive one with slope in the choroid. These results indicated the probable association of a decrease in retinal, choroidal and optic disk blood flow in the inferior and nasal quadrants as well as vessel width in the inferior nasal quadrant with visual field loss in the superior quadrant, and also demonstrated an increasing blood flow for enlargement of pallor. A decrease in BP was found to be related to reduced blood flow in choroid and optic disk impairment.

Efficacy and safety of latanoprost eye drops for glaucoma treatment: a 1-year study in Japan.

PURPOSE: To evaluate the intraocular pressure (IOP)-lowering effect and safety of latanoprost, a prostaglandin analogue, in patients with primary open-angle glaucoma or ocular hypertension. METHOD: One hundred and twenty-four Japanese patients with primary open-angle glaucoma or ocular hypertension were enrolled in this open-labeled study and were treated with 0.005% latanoprost once daily for 1 year. RESULTS: At all follow-up visits there was a significant (P < .001) reduction in IOP compared with the baseline value. After 1 year, the IOP was reduced by 5.4 +/- 2.9 (mean +/- SD) mm Hg from a baseline value of 23.5 +/- 2.2 mm Hg. No evidence of an upward drift in the IOP was observed during the treatment period. The most frequently reported adverse ocular events were mild conjunctival hyperemia and iris pigmentation. Very few adverse systemic events were observed. CONCLUSIONS: Latanoprost eye drops showed a marked and stable IOP-lowering effect during the 1-year treatment period. Furthermore, latanoprost was well-tolerated and should be a valuable contribution to the management of glaucoma.

[Long-term effect of topically applied isopropyl unoprostone on microcirculation in the choroid-retina].

PURPOSE: To study the long-term effect of topically applied 0.12% isopropyl unoprostone (unoprostone, Rescula) on microcirculation in the ocular fundus. MATERIALS AND METHODS: Using a laser speckle tissue circulation analyzer, normalized blur (NB), a quantitative index of blood flow velocity and tissue blood flow, was measured in the optic nerve head (ONH) and choroid-retina before and 4.5 hours after an instillation of placebo into both eyes in 11 normal human volunteers. Intraocular pressure (IOP), blood pressure, and pulse rate were also measured. A drop of unoprostone or the placebo was instilled into each eye in a double-blind manner twice a day for 21 days (the treated or untreated eye). RESULTS: Twenty-one days later, NB values in the ONH and the choroid-retina increased significantly and the IOP decreased significantly only in the treated eyes. Ocular perfusion pressure showed no significant changes. CONCLUSIONS: These results suggest that the increase of the blood flow in the microcirculation in the human ocular fundus following the relatively long-term topical application of unoprostone may be due to reduction in vascular resistance.

[Effect of the consumption of ethanol on the microcirculation of the human optic nerve head in the acute phase].

PURPOSE: The effect of the consumption of ethanol on the circulation of the optic nerve head (ONH) in the human eye in the acute phase and its mechanism were studied. METHODS: Eleven volunteers drank a bottle of beer (633 ml) with or without ethanol (29.5 g). Normalized blur (NB), a quantitative index of blood flow velocity, was measured in the temporal site of the ONH. NB, blood pressure (BP) and pulse rate (PR) were measured before, immediately after, and every 15 minutes for 90 minutes after consumption. Intraocular pressure (IOP) and plasma ethanol concentration were measured before, and 30 and 90 minutes after consumption. Genotyping of the aldehyde dehydrogenase (ALDH) 2 gene was also performed. RESULTS: NB in the ONH increased significantly from 15 to 45 minutes after consumption of ethanol and the maximum increase was 14% at 15 minutes. IOP was lowered at 90 minutes after consumption, but it was not significant. Mean BP was lowered significantly after 60 minutes. PR and ocular perfusion pressure did not change. A significant correlation was found between plasma ethanol concentration at 30 minutes and maximum NB. NB in the ALDH 2-deficient group was significantly larger from 15 to 45 minutes after consumption than in the proficient group. CONCLUSION: It appeared that the consumption of ethanol can increase the blood flow in the human ONH in the acute phase through decreased resistance in blood vessels induced by acetaldehyde, a metabolite of ethanol.

Experimental optic cup enlargement caused by endothelin-1-induced chronic optic nerve head ischemia.

PURPOSE: Vascular insufficiency of the optic nerve head may contribute to glaucomatous optic neuropathy, especially in normal-tension glaucoma. We investigated the effect of chronic optic nerve head ischemia, created by repeated intravitreal injection of endothelin-1 (ET-1), on the morphology and function of the optic nerve. METHODS: In pigmented rabbits, we injected ET-1 (10(-6) M, 10 microL) into the posterior vitreous of one eye twice a week for 4 weeks (N = 7). The vehicle for ET-1 was injected into the contralateral eye as a control (N = 7). The subsequent observation period was set at 8 weeks. The microcirculation of the optic nerve head was noninvasively monitored with a laser speckle circulation analyzer. To evaluate the changes of visual function, visual-evoked potentials were recorded. Morphologic changes of the optic nerve head were analyzed with stereography, and the ratio of cup area (CA) to disk area (DA) was measured by calculating the number of pixels in each area with a microcomputer. RESULTS: Capillary blood flow in the optic nerve head was continuously below 80% of the baseline throughout the study. The visual-evoked potential latency was significantly delayed in ET-1-treated eyes. The CA/DA ratio was significantly increased relative to baseline in the ET-1 treated eyes. Histologic examination showed axonal loss and demyelination affecting the prelaminar portion of the optic nerve. The intraocular pressure was not significantly different from the control value. CONCLUSION: Optic nerve head ischemia could contribute to the enlargement and excavation of the disk cup independent of the intraocular pressure level.

Effect of lomerizine, a new Ca(2+)channel blocker, on the microcirculation in the optic nerve head in conscious rabbits: a study using a laser speckle technique.

We examined the effect of a new Ca(2+)channel blocker, lomerizine (KB-2796), and compared it with that of nilvadipine, on the optic nerve head circulation in conscious rabbits using a laser speckle method. Lomerizine (0.03, 0.1 and 0.3 mg kg(-1), i.v.) and nilvadipine (0.003, 0.01 and 0.03 mg kg(-1), i.v.) each significantly increased the normalized blur values (an index of tissue blood velocity) in the optic nerve head in a dose-dependent manner. Neither lomerizine nor nilvadipine caused a significant change in intraocular pressure. Lomerizine produced no significant change in mean arterial blood pressure, although at 0.3 mg kg(-1), i. v. heart rate was significantly increased 5 min after its administration. In contrast, nilvadipine significantly decreased mean arterial blood pressure at 5 to 15 min after its administration and increased heart rate at 5-30 min after its administration (both effects being dose-dependent). Our results indicate that while lomerizine, like nilvadipine, increased tissue blood velocity in the optic nerve head, it did not affect mean arterial blood pressure at the doses that affected optic nerve head circulation, unlike nilvadipine. The plasma concentration of lomerizine (free base) obtained from rabbits at 15 min after administration at a dose of 0. 03 mg kg(-1)i.v., when time there was a significant increase in tissue blood velocity in the optic nerve head, was very similar to plasma concentration with healthy subjects receiving lomerizine at 10 mg (5 mgx2) day(-1), p.o., a dose that achieved a significant reduction in the frequency and mean duration of headache attacks but did not affect the blood pressure or heart rate. These results suggest that lomerizine may be clinically effective in favorably affecting the optic nerve circulation without producing systemic effects such as the hypotension seen during treatment with other Ca(2+)channel blockers.