Positive selection of gamma delta CTL by TL antigen expressed in the thymus.

To elucidate the funciton of the mouse TL antigen in the thymus, we have derived two TL transgenic mouse strains by introducing Tl alpha 2-3 of A strain origin with its own promoter onto a C3H background with no expression of TL in the thymus. These transgenic mouse strains, both of which express high levels of Tla2-3-TL antigen in their thymus, were analyzed for their T cell function with emphasis on cytotoxic T lymphocyte (CTL) generation. A T cell response against TL was induced in Tg. Tla2-3-1, Tg. Tla2-3-2, and control C3H mice by skin grafts from H-2Kb/T3b transgenic mice, Tg.Con.3-1, expressing T3b-TL ubiquitously. Spleen cells from mice that had rejected the T3b-TL positive skin grafts were restimulated in vitro with Tg. Con.3-1 irradiated spleen cells. In mixed lymphocyte cultures (MLC), approximately 20% and 15% of Thy-1+ T cells derived from Tg.Tla2-3-1 and Tg.Tla2-3-2, respectively, expressed TCR gamma delta, whereas almost all those from C3H expressed TCR alpha beta. The MLC from Tg. Tla2-3-2 and C3H demonstrated high CTL activity against TL, while those from Tg. Tla2-3-1 had little or none. The generation of gamma delta CTL recognizing TL in Tg. Tla2-3-2, but not C3H mice, was confirmed by the establishment of CTL clones. A total of 14 gamma delta CTL clones were established from Tg. Tla2-3-2, whereas none were obtained from C3H. Of the 14 gamma delta CTL clones, 8 were CD8+ and 6 were CD4-CD8- double negative. The CTL activity of all these clones was TL specific and inhibited by anti-TL, but not by anti-H-2 antibodies, demonstrating that they recognize TL directly without antigen presentation by H-2. The CTL activity was blocked by antibodies to TCR gamma delta and CD3, and also by antibodies to CD 8 alpha and CD8 beta in CD8+ clones, showing that the activity was mediated by TCR gamma delta and coreceptors. The thymic origin of these gamma delta CTL clones was indicated by the expression of Thy-1 and Ly-1 (CD5), and also CD8 alpha beta heterodimers in CD8+ clones on their surfaces and by the usage of TCR V gamma 4 chains in 12 of the 14 clones. Taken together, these results suggest that Tla2-3-TL antigen expressed in the thymus engages in positive selection of a sizable population of gamma delta T cells.

Chorioretinal temperature monitoring during transpupillary thermotherapy for choroidal neovascularisation.

AIMS: To investigate the difference in temperature rise between normal choroid and choroidal revascularisation (CNV) during transpupillary thermotherapy (TTT) and the relation between laser spot size and power in the rat fundus. METHODS: A modified slit lamp, which was installed with two laser wavelengths (490 nm for illumination and fluorescein excitation and 810 nm for hyperthermia), was developed for TTT and temperature monitoring. Temperature rise during TTT was monitored by observing fluorescence released from thermosensitive liposomes encapsulating carboxyfluorescein. Two types of liposomes were prepared; their phase transition temperatures were 40 degrees C and 46 degrees C, respectively. Laser power settings required to observe fluorescence released from 46 degrees C liposome in normal choroid or CNV were compared. Next, the power settings with 0.5 mm and 0.25 mm spot sizes were compared following administration of 40 degrees C liposome or 46 degrees C liposome. RESULTS: The minimum power values when release from 46 degrees C liposome was observed showed a significant difference in distribution of power values between normal choroid and CNV. CNV required significantly higher power than normal choroid. With 40 degrees C liposome, the power was 9.7 (1.9) mW (mean (SD)) at a spot size of 0.25 mm, and 12.1 (1.6) mW at 0.5 mm, respectively. When using 46 degrees C liposome, the power setting was 10.2 (1.2) mW at a spot size of 0.25 mm, and 14.6 (2.2) mW at 0.5 mm, respectively. CONCLUSIONS: CNV demonstrated varying heat conduction, compared with normal choroid. Laser power required to raise the temperature should not necessarily be doubled, even when the spot size is doubled. Close attention should be given to the selection of power settings when performing TTT for CNV.

Alterations of retinal microcirculation in response to scatter photocoagulation.

PURPOSE: To perform acridine orange digital fluorography on rats after scatter photocoagulation to investigate alterations of retinal microcirculation at the capillary level, the authors used leukocyte dynamics as a parameter. METHODS: Twenty-five pigmented rats (Long-Evans) were studied. Argon laser photocoagulation, extending 6 disc diameters from the optic disc, was delivered to one half of the retina, and the other half was untreated. The total number of burns was 200 +/- 10. Leukocyte hemodynamics in retinal microcirculation were evaluated 4, 7, 14, and 28 days after photocoagulation by acridine orange digital fluorography. The fundus image was obtained by using an argon laser in a scanning laser ophthalmoscope and was recorded on magnetic tapes at a video rate. The images were analyzed by a personal computer-based image analysis system. RESULTS: Leukocyte velocities in the retinal capillaries were significantly decreased immediately after photocoagulation. In the laser-treated area, mean capillary leukocyte velocities were 0.73, 0.92, 1, and 1.3 mm/second on days 4, 7, 14, and 28, respectively (velocity in normal control animals 1.4 mm/second). In addition, leukocyte hemodynamics were compromised in the untreated retina: Mean capillary leukocyte velocities were 0.88, 1.1, 1.2, and 1.3 mm/second on days 4, 7, 14, and 28, respectively. Twenty-eight days after photocoagulation, the velocities recovered to normal values in the treated and the untreated areas of the retina. CONCLUSIONS: Retinal capillary hemodynamics were impaired after scatter photocoagulation, and the hemodynamics in the untreated retina were also affected. Photocoagulation to the retina may influence capillary hemodynamics by diffusible chemical substances and by direct tissue injury.

Quantitative evaluation of leukocyte dynamics in retinal microcirculation.

PURPOSE: Leukocyte rheology may play a key role in microcirculation because leukocytes have unique properties, such as large cell volume, high cytoplasmic rigidity, and low deformability. However, only a few methods are available to study the dynamic behavior of leukocytes in retinal microcirculation. The authors developed a new method to analyze directly movements of leukocytes in the retinal vessels of primates. METHODS: Acridine orange, which has been used as a nuclear stain in histochemistry and cytochemistry, was injected intravenously into cynomolgus monkeys for a vital staining of leukocytes. The fundus image was generated with the argon blue laser and a scanning laser ophthalmoscope. The images were recorded on a magnetic tape and evaluated with a personal computer-based image analysis system. RESULTS: Each leukocyte was recognized as a single fluorescent dot moving in the retinal vessels. It was possible to analyze the spatial and temporal dynamics of individual leukocytes in the capillaries. Some leukocytes passed through the capillaries, plugging transiently under the physiological condition. Leukocytes that stayed in the same position for a few minutes may have stuck to the endothelium as a result of leukocyte-endothelial interactions. In the postcapillary vessels, leukocytes tended to be displaced from the center stream toward the vessel walls. The mean flow velocity of leukocytes in the perifoveal capillary was 0.92 +/- 0.32 mm/sec. CONCLUSIONS: This study clearly demonstrated that rheologic behaviors of leukocytes in the retinal microcirculation can be studied through the vital staining with acridine orange in vivo. The authors' results suggest a potential role of leukocytes in retinal vascular flow disturbances. This study may open the door to the investigation of leukocyte hemodynamics in the retinal microcirculation in vivo.

Prednisolone, platelet-activating factor receptor antagonist, or superoxide dismutase reduced leukocyte entrapment induced by interferon alpha in retinal microcirculation.

PURPOSE: Interferon (IFN) alpha has been suggested as a possible treatment for choroidal neovascularization. However, the pathogenesis of retinal complications after IFN therapy still is unknown. Previously, we have shown that IFN alpha induced leukocyte entrapment in retinal microcirculation. The current study was designed to determine if leukocyte entrapment can be reduced by the agents that modulate leukocyte-endothelial adherence. METHODS: Interferon alpha was administered intravenously in rats. Simultaneously, prednisolone (PSL), platelet-activating factor receptor antagonist (CV-6209), or superoxide dismutase (SOD) was given to the rats. Leukocyte dynamics were observed with acridine orange (AO) digital fluorography, which uses a nuclear fluorescent dye of AO and scanning laser ophthalmoscopy. The number of trapped leukocytes in each group was assessed with a personal computer-based image analysis. RESULTS: Interferon alpha induced leukocyte entrapment in retinal microcirculation and increased leukocyte adherence to the vessel walls. The simultaneous administration of PSL, CV-6209, or SOD inhibited leukocyte adherence to the venous walls and significantly reduced the number of trapped leukocytes. CONCLUSIONS: Acridine orange digital fluorography was helpful to quantitate leukocyte-endothelial interactions in retinal microcirculation. The results suggested that increased leukocyte adherence after IFN alpha administration was reduced significantly by PSL, CV-6209, or SOD. These agents may be useful to prevent IFN-induced microcirculatory disturbances.

In vivo quantification of leukocyte behavior in the retina during endotoxin-induced uveitis.

PURPOSE: The interaction between leukocytes and vascular endothelial cells plays an important role in various inflammatory disorders. This study evaluated leukocyte behavior in the retina during endotoxin-induced uveitis (EIU) in vivo. METHODS: EIU was induced in female Lewis rats by footpad injection of lipopolysaccharide (LPS). The time-course changes of retinal leukocyte behavior were followed at 1.5, 3, 4.5, 6, 12, 24, 48, 72, and 120 hours after LPS treatment using acridine orange digital fluorography, consisting of high-resolution images from a scanning laser ophthalmoscope and a fluorescent nuclear dye of acridine orange. RESULTS: Major retinal vessels were significantly dilated (P < 0.05) at 4.5 hours after LPS injection. The vasodilation, marked in veins, became maximum at 24 hours and subsided at 72 hours. Leukocytes were observed rolling along the walls of major veins at 4.5 hours. The number of rolling leukocytes gradually increased and reached a peak level of 33.8 +/- 3.4 cells/minute per major vein at 12 hours. Leukocyte rolling was still observed at 72 hours. No rolling of leukocytes was observed along the arterial walls throughout any experiments. The velocities of rolling leukocytes were determined at 6, 12, 24, and 48 hours. The leukocyte rolling velocity at 6 hours was significantly slower (33.3 +/- 2.8 microns/second, P < 0.05) than at the other three times (average, 46.6 microns/second). Cellular infiltration into the vitreous cavity was detected at 24 hours and reached its maximum at 48 hours. CONCLUSIONS: This study demonstrates that it is possible to evaluate EIU by investigating retinal leukocyte behavior and that vasodilation of major retinal vessels and leukocyte-endothelial interactions precede inflammatory cell emigration into the vitreous. This method may be useful to quantify the severity of inflammation in EIU.

Visualization and quantitative analysis of leukocyte dynamics in retinal microcirculation of rats.

PURPOSE: Recent studies have demonstrated that leukocytes play an important role in microcirculatory flow disturbances. A few methods are available to investigate leukocyte dynamics in retinal microcirculation. The authors explored leukocyte dynamics in the retina of rats with acridine orange digital fluorography. METHODS: Acridine orange digital fluorography produces high-resolution images from a scanning laser ophthalmoscope with the use of a fluorescent nuclear dye of acridine orange, which has been used for staining nucleic acids of cells in histochemical and cytochemical studies. The images were recorded on S-VHS tapes and were investigated with a personal computer-based image analysis system. RESULTS: Fluorescent leukocytes in the retinal microcirculation were visualized. Highly magnified images could be obtained because of the high dioptric power of the rat eye compared with the primate eye. It was possible to observe leukocyte deformation in narrow capillaries and nuclei of vascular endothelium. At arteriolar bifurcations, leukocytes moved preferentially into the branch with the higher flow rate. "Preferential channels" were identified in which predominantly leukocytes were delivered; the channels were characterized by high flow velocity and a straight, short capillary route. The average leukocyte velocities of the arteries, veins, and capillaries are 29.5 +/- 7.3, 17.4 +/- 5.3, and 1.4 +/- 0.4 mm/second, respectively. CONCLUSIONS: This study demonstrates that microcirculatory dynamics of leukocytes can be visualized and analyzed quantitatively in rats in vivo with acridine orange fluorography. This method may be a promising tool to reveal how leukocytes contribute to retinal flow disturbances under various pathologic conditions.

A new vitreal drug delivery system using an implantable biodegradable polymeric device.

PURPOSE: The authors evaluated the feasibility of using an implantable biodegradable polymeric device to deliver drugs into the vitreous humor. METHODS: Two types of devices were prepared by compression-molding polymers of poly(DL-lactic acid) of two different molecular weights. The molecular weights of the poly(DL-lactic acid) used were 5,600 (device-1) and 9,100 (device-2). Sodium fluorescein (NaF) served as a hydrophilic drug marker. The release of the dye from the devices was studied in vitro. The intravitreal kinetics of NaF was evaluated in rabbits in vivo by fluorophotometry. The eyes were evaluated electrophysiologically and histologically to determine if there were toxic effects. RESULTS: Device-1 and device-2 released NaF for more than 25 and 45 days, respectively, in vitro. Detectable concentrations of NaF were present in the vitreous up to 17 days (device-1) and 28 days (device-2). Both types of devices were well tolerated, with no noted toxic effects. CONCLUSIONS: These results suggested that this device may be a potentially effective system to deliver drugs in the vitreous.

Radiation-induced leukocyte entrapment in the rat retinal microcirculation.

PURPOSE: To evaluate the effects of irradiation on leukocyte dynamics in the rat retinal microcirculation. METHODS: Thirty-five Brown-Norway rats received a dose of 10 Gy irradiation in one fraction. Leukocyte dynamics were studied with acridine orange digital fluorography, in which a nuclear fluorescent dye of acridine orange is used and examined by scanning laser ophthalmoscope. This technique allowed visualization of fluorescent leukocytes in vivo. The leukocyte dynamics were evaluated at 0, 4, 7, 14, 30, and 60 days after the irradiation. RESULTS: Mean leukocyte velocity in the retinal capillaries decreased immediately. It partially recovered on day 4 but then gradually decreased up to the 2-month mark. Low-dose irradiation induced entrapment of leukocytes in the retinal microcirculation. The number of entrapped leukocytes gradually increased with time. The major retinal vessels significantly constricted immediately after irradiation. The diameter was reduced by 76% in arteries and 75% in veins, 2 months after irradiation. CONCLUSIONS: Entrapped leukocytes may be activated and exacerbate vascular injury and microinfarction and thus may participate in the pathogenesis of radiation retinopathy.

Visualization of leukocyte dynamics in the choroid with indocyanine green.

PURPOSE: To report a method to evaluate leukocyte dynamics in the choroidal circulation with indocyanine green (ICG) angiography. METHODS: Nonpigmented and pigmented rats were administered ICG solution intravenously. The fundus image was obtained with a scanning laser ophthalmoscope and recorded on magnetic tapes at a video rate (30 frames/second). The images were analyzed with a personal computer-based image analysis system. RESULTS: On ICG angiography, hyperfluorescent dots were seen moving along the choroidal vessels and in the retinal vessels several minutes after injection. These fluorescent dots were thought to be circulating leukocytes stained with ICG. The micrographs of blood smears after ICG injection showed intense fluorescence of leukocytes. Computer-assisted image analysis allowed tracing of these fluorescent dots using a frame-by frame method. CONCLUSIONS: Results of this study indicated that ICG can be used for vital staining of leukocytes and that it is possible to evaluate leukocyte movement in the choroidal circulation in vivo in rats.

PKC-beta inhibitor (LY333531) attenuates leukocyte entrapment in retinal microcirculation of diabetic rats.

PURPOSE: The activity of protein kinase C (PKC), preferentially beta isoform of PKC, has been shown to be elevated in the diabetic retina. Recently, LY333531, a specific inhibitor of PKC-beta, has been reported to improve the decrease of retinal blood flow in early diabetes. Increased leukocyte entrapment has been suggested to be involved in blood flow disturbances in the early diabetic retina. This study was designed quantitatively to evaluate leukocyte entrapment in the retinal microcirculation of diabetic rats and the effect of LY333531 on leukocyte entrapment. METHODS: Diabetes was induced in male Long-Evans rats by intraperitoneal injection of streptozotocin (60 mg/kg). LY333531 (0.1, 1.0, or 10.0 mg/kg/d) was administered orally during a 4-week diabetic period. Leukocyte entrapment in the retinal microcirculation was quantitatively evaluated in vivo with acridine orange digital fluorography. RESULTS: The number of leukocytes trapped in the retinal microcirculation of diabetic rats (mean +/- SEM; 14.3 +/- 1.3 cells/mm2) was significantly increased, compared with nondiabetic control rats (7.5 +/- 0.3 cells/mm2; P < 0.0001). Oral administration of LY333531 significantly decreased the number of leukocytes trapped in the retinal microcirculation of diabetic rats (10.9 +/- 0.6, 11.3 +/- 0.7, and 10.4 +/- 0.4 cells/mm2 with LY333531 0.1, 1.0, and 10.0 mg/kg/d, respectively; P < 0.05). CONCLUSIONS: Treatment with LY333531 attenuated the increase of leukocyte entrapment in the retinal microcirculation during the period of early diabetes. This effect may contribute to the improvement of abnormal retinal blood flow in early diabetes with LY333531. LY333531 might have a therapeutic efficacy in preventing microcirculatory flow disturbances by trapped leukocytes in the early diabetic retina.

Evaluation of retinal microcirculatory alterations in the Goto-Kakizaki rat. A spontaneous model of non-insulin-dependent diabetes.

PURPOSE: To evaluate retinal microcirculation in the spontaneous diabetic GK (Goto-Kakizaki) rat over an extended time. METHODS: The dye-dilution technique with scanning laser ophthalmoscope-based fluorescein angiography was used to evaluate retinal circulation in GK rats with diabetes of 1, 3, and 5 months' duration and in age-matched controls. Scanning laser ophthalmoscope fluorescein angiograms were recorded after a 10-microliter bolus of 10% sodium fluorescein was injected into the tail vein, followed by a flush of 0.1 ml saline. Retinal mean circulation times (MCTs), vessel diameters, and retinal segmental blood flows (SBFs) were determined using computer-assisted image analysis on a frame-by-frame basis. RESULTS: The MCTs were significantly prolonged (P< 0.01) in the GK rat groups (2.60 +/- 0.31, 2.74 +/- 0.28, and 2.84 +/- 0.38 seconds at 1, 3, and 5 months' duration of diabetes, respectively) compared to the age-matched controls (1.94 +/- 0.20, 1.99 +/- 0.12, and 1.91 +/- 0.22 seconds, respectively). No significant differences were observed in the retinal arterial and venous diameters between groups at each time period. The SBFs were significantly reduced (P< 0.03) in the GK rat groups (12.0 +/- 1.5, 12.1 +/- 2.0, and 11.8 +/- 2.5 x 10(2) micrometer squared/second at 1, 3, and 5 months' duration of diabetes, respectively) compared to the controls (16.0 +/- 2.2, 16.7 +/- 1.8, and 17.2 +/- 2.5 x 10(2) micrometer squared/second, respectively). In either group, no significant changes with growth were observed in MCT, vessel diameters, or SBF, although the MCTs in the GK rat group tended to lengthen, and arterial and venous diameters in the GK rat group tended to increase with duration of diabetes. Goto-Kakizaki rats did not exhibit dense cataracts, the retinal circulation could be observed, and morphologic changes of diabetic retinopathy did not develop throughout the experimental period. CONCLUSIONS: A significant prolongation in MCT and a significant reduction in SBF appeared in GK rats at an early stage in diabetes. This tendency continued until 5 months' duration of diabetes. These results suggest that retinal circulatory abnormalities are found before observable retinopathy development in GK rats and that there may be some mechanism causing a reduction in SBF without changing major retinal vessel diameters at an early stage in non-insulin-dependent diabetes mellitus (NIDDM). In addition, this study demonstrates that the GK rat will be a useful model of non-insulin-dependent diabetes mellitus to evaluate retinal circulation over an extended time.

In vivo evaluation of platelet-endothelial interactions in retinal microcirculation of rats.

PURPOSE: This study was designed to develop a new method to evaluate the dynamics of platelets in the retinal microcirculation in vivo and to investigate quantitatively the platelet-endothelial interactions in rat retina with the use of this system. METHODS: Isolated platelet samples were labeled with carboxyfluorescein diacetate succinimidyl ester. After intravenous administration, platelet behavior in the retinal microcirculation was evaluated with a scanning laser ophthalmoscope. The images were recorded on S-VHS videotape and analyzed with a computer-assisted image analysis system. The platelet- endothelial interactions in the retinal microcirculation were also investigated with the use of lipopolysaccharide-stimulated endothelium or platelets activated with thrombin. RESULTS: Fluorescent platelets were recognized as distinct dots in the retinal microcirculation and could be traced frame by frame. The velocity of platelets in the retinal arteries, capillaries, and veins was 26.1+/-6.4, 1.6+/-0.4, and 19.9+/-8.2 mm/sec, respectively. In control rats, even the activated platelets showed minimal interaction with retinal endothelial cells. In contrast, stimulated retinal endothelium showed active platelet- endothelial interactions; many platelets were observed rolling and adhering along the major retinal veins. The interactions between platelets and stimulated endothelial cells were substantially inhibited with the injection of P-selectin monoclonal antibody. CONCLUSIONS: The present study demonstrated a new method to visualize platelet behavior in the retinal microcirculation in vivo. This method will allow quantitative evaluation of platelet dynamics and platelet- endothelial interactions in retinal pathologic conditions.

Administration of 17beta-estradiol attenuates retinal ischemia-reperfusion injury in rats.

PURPOSE: Accumulating evidence has suggested that 17beta-estradiol exerts protective effects against ischemic damage in various organs. In addition, leukocytes that accumulate in postischemic tissues are thought to play a central role in ischemia-reperfusion injury. This study was designed to evaluate quantitatively the inhibitory effects of 17beta-estradiol on leukocyte accumulation during ischemia-reperfusion injury and on subsequent retinal damage after transient retinal ischemia. METHODS: Transient (60 minutes) retinal ischemia was induced in male rats by temporary ligation of the optic nerve. Thirty minutes before induction of ischemia, 17beta-estradiol (0.1 mg/kg) was administered intraperitoneally. At 6, 12, 24, and 48 hours after reperfusion, leukocyte accumulation in the retina was evaluated in vivo by means of acridine orange digital fluorography. Histologic and electroretinographic (ERG) studies were carried out to evaluate retinal damage. RESULTS: Treatment with 17beta-estradiol significantly inhibited postischemic leukocyte accumulation; the maximum number of accumulating leukocytes was reduced by 35.7% at 24 hours after reperfusion (P = 0.01). Histologic examination showed that administration of 17beta-estradiol significantly reduced retinal damage, which was most obvious in the inner retina, 168 hours after reperfusion (P = 0.0001). ERG studies at 12 and 168 hours after reperfusion showed that recovery of the b-wave amplitude was significantly improved with treatment of 17beta-estradiol (P = 0.023). CONCLUSIONS: The present study demonstrated the inhibitory effects of 17beta-estradiol on leukocyte accumulation and subsequent tissue injury during retinal ischemia-reperfusion injury.

Inhibitory effect of ischemic preconditioning on leukocyte participation in retinal ischemia-reperfusion injury.

PURPOSE: Recent reports have shown that ischemic preconditioning induces strong protection against retinal damage by subsequent prolonged ischemia and that this protection is mediated by mechanisms involving the adenosine A1 receptor. This study was designed to evaluate quantitatively the effects of ischemic preconditioning on leukocyte-mediated reperfusion injury after transient retinal ischemia and to define the role of the adenosine A1 receptor in these effects. METHODS: Transient retinal ischemia was induced in male rats by temporary ligation of the optic nerve. Ischemic preconditioning (5 minutes of ischemia) was induced 24 hours before 60 minutes of ischemia. The adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) was administered intramuscularly immediately after ischemic preconditioning. Leukocyte behavior in the retina after 60 minutes of ischemia was evaluated in vivo with acridine orange digital fluorography. RESULTS: Ischemic preconditioning inhibited leukocyte rolling. The maximum number of rolling leukocytes was reduced to 3.0% at 12 hours after reperfusion (P < 0.01). Subsequent leukocyte accumulation was also decreased with ischemic preconditioning. The maximum number of accumulated leukocytes was reduced to 22.6% at 24 hours after reperfusion (P < 0.01). These inhibitory effects were suppressed by administration of DPCPX (P < 0.0001). The numbers of rolling leukocytes at 12 hours after reperfusion and accumulated leukocytes at 24 hours after reperfusion were 102.7% (NS) and 83.4% (P < 0.01), respectively, compared with the number without ischemic preconditioning. CONCLUSIONS: The present study demonstrates the inhibitory effects of ischemic preconditioning on leukocyte rolling and subsequent leukocyte accumulation during retinal ischemia-reperfusion injury. Furthermore, the adenosine A1 receptor may play an important role in these inhibitory effects.

Interferon alfa induces leukocyte capillary trapping in rat retinal microcirculation.

BACKGROUND: Interferon alfa has been suggested as a possible treatment for choroidal neovascularization. However, retinal complications following interferon therapy have been reported. OBJECTIVE: To evaluate the effects of interferon alfa on leukocyte dynamics in the rat retinal microcirculation. METHODS: Interferon alfa of different doses was intravenously administered in rats. Leukocyte dynamics were observed with acridine orange digital fluorography, which uses a nuclear fluorescent dye of acridine orange and scanning laser ophthalmoscopy. This technique allows visualization of leukocyte movements in the retinal microcirculation in vivo. RESULTS: After interferon alfa was administered, leukocytes adhered to vascular walls and became trapped in the retinal microcirculation. Leukocyte trapping was dose-dependent. CONCLUSIONS: Interferon alfa increased leukocyte adherence to vascular endothelium and subsequent leukocyte trapping in the retinal capillaries. Interferon alfa may activate leukocytes, and activated leukocytes may be involved in the pathogenesis of microinfarction associated with interferon-induced retinopathy.

Effect of alcohol on plasma secretin concentration and pancreatic secretion in dogs.

We studied the effect of alcohol on plasma secretin concentration and pancreatic secretion in dogs with gastric cannulas and pancreatic fistulas. Intragastric administration of ethanol resulted in significant increases in pancreatic secretion of water and bicarbonate, which accompanied simultaneous increase in plasma secretin concentration. A more pronounced increase in pancreatic secretion occurred when ethanol was administered in the postprandial period. Integrated secretin release after a meal, 4.5 +/- 0.7 ng/ml-2 hr, had also increased significantly to 7.6 +/- 1.3 ng/ml-2 hr when ethanol was given in addition to a meal. Cimetidine pretreatment blocked the increase in plasma secretin concentration and pancreatic secretion in response to a meat meal and ethanol administration. This action of cimetidine paralleled its potent inhibitory effect on the exaggerated gastric acid secretion from Heidenhain pouches of dogs in response to ingestion of a meal and ethanol administration. Intraduodenal infusion of ethanol, however, failed to affect the plasma secretin concentration and pancreatic secretion. The present study indicates that alcohol stimulates release of endogenous secretin and pancreatic secretion by increasing duodenal acid load from the stomach stimulated by ethanol administration in dogs.

Is extensive lymphadenectomy necessary for surgical treatment of intramucosal carcinoma of the stomach?

This study was undertaken to elucidate those histological and gross features associated with gastric carcinoma that can be adequately treated by gastrectomy with less aggressive lymphadenectomy. The frequency of metastasis to the lymph nodes was analyzed in 514 cases of resected, solitary, gastric carcinomas. The frequency of metastasis to the lymph nodes increased in proportion to the increase in the extent of penetration by the cancer into the gastric wall. Lymph nodes were not involved in cases of intramucosal carcinoma of the intestinal type, by Laurén's histological classification. By contrast, metastasis to the lymph nodes was observed in cases of intramucosal carcinoma of the diffuse type, by Laurén's classification. We conclude that extensive lymphadenectomy is not mandatory for patients with intramucosal carcinoma of the stomach of the protruded type, since the lymph nodes do not become involved in this type of gastric carcinoma.

24-Hour plasma secretin level and pancreatic secretion in dog.

Plasma secretin concentrations were determined and duodenal pH was recorded continuously for a period of 24 hours after ingestion of a meal in 3 dogs with gastric cannula and duodenal cannula and in 4 dogs with pancratic fistulae. The mean plasma secretin concentration increased significantly after a meal and it remained elevated for the first 12-hour period (peak at 30 min). Duodenal pH frequently decreased below 4.5 during the first 12-hour postprandial period, but it remained above 5.0 during the second 12 hours. Pancreatic secretion peaked during the first hour of meal ingestion and remained elevated until the end of 12 hours. The increased plasma secretin level in pancreatic fistula dog during the postprandial period was significantly greater than that of duodenal cannula dog, but the trends of increase in the secretin levels were quite identical. The present study indicates that: (1) plasma secretin concentration increases significantly within 30 min after a meal and remains increased during the first 12-hour period, (2) duodenal pH frequently decreaded below 4.5 during the same 12 hours but more frequently during the first 6 hours, and (3) a significant increase in pancreatic water, HC03- and protein occurred during the same time period.

A randomized study comparing VMCP and MMPP in the treatment of multiple myeloma.

PURPOSE: To compare VMCP, a multidrug combination chemotherapy comprising vincristine (VCR), melphalan (MPH), cyclophosphamide (CPM) and prednisolone (PSL), with MMPP comprising MPH, ranimustine (MCNU), procarbazine, and PSL as induction, to elucidate the value of alternating combination chemotherapy, and to search for an appropriate maintenance therapy in multiple myeloma. METHODS: At 16 institutions in the Nagoya City area, we carried out a randomized trial of VMCP versus MMPP as the initial treatment. Patients who were refractory or resistant to the initial therapy were crossed over into the other arm (crossover trial). For patients who achieved a partial response (PR) or a minor response (MR) and in whom the paraprotein level ceased to decrease, the maintenance therapy was randomized either to an MPH/PSL combination (MP) or to alternating combination therapy (AT) with VMCP and MMPP. RESULTS: In the 94 evaluable patients of the 111 enrolled, the response rate (PR rate) was 27.7% (13/47) in the VMCP arm and 44.7% (21/47) in the MMPP arm (P = 0.0859). The crossover trial resulted in a PR rate of 15.8% (3/19) for the VMCP-->MMPP crossover and 14.3% (2/14) for the MMPP-->VMCP crossover. The median survival time was 23.4 months for those initially begun in the VMCP arm and 24.9 months for those in the MMPP arm, showing a tendency for better survival during a follow-up of 2-6 years with MMPP treatment, but without statistical significance. The survival time of patients with progressive disease was significantly shorter than that of patients with PR, MR or no change (NC). However, there was no significant difference in the survival rate among those who achieved PR, MR, or NC. As to the maintenance therapy, there was no significant difference in survival between MP therapy and AT. Patients who reached a plateau phase survived significantly longer than those who did not. Except for six cases of grade 3 or 4 neurotoxicity in the VMCP arm, there was no significant difference in the hematologic or gastrointestinal toxicity between the two arms. CONCLUSIONS: We conclude that VMCP is less effective for myeloma than MMPP as the induction treatment, that alternating noncrossresistant chemotherapeutic combinations do not offer an advantage in multiple myeloma, and that patients who reach a plateau phase have a significantly longer survival time.