Liposome-Encapsulated Hemoglobin Improves Tumor Oxygenation as Detected by Near-Infrared Spectroscopy in Colon Carcinoma in Mice.

Liposome-encapsulated hemoglobin (LEH) with high (h-LEH, P50 O2  = 10 mm Hg) or low O2 affinity (l-LEH, P50 O2  = 40 mm Hg) may improve O2 delivery to sensitize tumor tissues for radiotherapy. A total of 10 mL/kg of h-LEH, l-LEH, red blood cells (RBCs), or saline was infused in mice transplanted with murine colon carcinoma with near-infrared spectroscopy (NIRS) detectors set at the tumor (right leg) and intact muscle (left leg). NIRS recorded changes in the amount of oxyhemoglobin (oxyHb), deoxyhemoglobin (deoxyHb), and their sum (tHb) with the animals spontaneously breathing room air (10 min), pure O2 (5 min), and then back to room air. The tumor was finally excised for histological examination. In mice treated with h-LEH, tHb significantly increased compared to mice receiving other solutions. The magnitude was significantly attenuated in the tumor compared to the intact muscle under room air. Reciprocal changes in oxyHb and deoxyHb between intact muscle and tumor in response to infused solutions allowed assumption of average tissue PO2 between 30 and 40 mm Hg in muscle and at around 10 mm Hg in tumor. While O2 respiration increased oxyHb and decreased deoxyHb both in muscle and tumor, their sum or tHb consistently decreased in muscle and increased in tumor regardless of preceding infusion. Such responses were totally reversed when mice were placed under hypoxia (10% O2 ), suggesting that a lack of physiological circulatory regulation in tumor may account for heavier immunohistochemical staining for human hemoglobin in tumors of mice treated with h-LEH than with l-LEH. The results suggest that h-LEH may cause significant tumor oxygenation compared to RBC, l-LEH, or saline probably due to its nanometer size (vs. RBC) and high O2 affinity (vs. l-LEH) without increasing O2 content in the intact tissue (vs. O2 respiration) probably due to a lack of physiological circulatory regulation.

Effect of Oxygen Affinity of Liposome-Encapsulated Hemoglobin on Cerebral Ischemia and Reperfusion as Detected by Positron Emission Tomography in Nonhuman Primates.

We tested a hypothesis that liposome-encapsulated hemoglobin (LEH) with high oxygen (O2 ) affinity (h-LEH, P50 O2 = 10 mm Hg) may work better than LEH with low O2 affinity (l-LEH, P50 O2 = 40 mm Hg) in cerebral ischemia and reperfusion injury using positron emission tomography (PET) in primates undergoing middle cerebral artery (MCA) occlusion and reperfusion. Cerebral blood flow (CBF), O2 extract fraction (OEF), and cerebral metabolic rate of O2 (CMRO2 ) were successively determined by PET before ischemia, at 2 h of ischemia, immediately after reperfusion, and 3 h after reperfusion. Five minutes after MCA occlusion, 10 mL/kg of h-LEH (n = 6) was intravenously infused and compared with the results from previous data of monkeys treated with l-LEH (n = 6), empty liposome (n = 4), or saline (n = 8) as control. After the series of PET studies, the integrated area of cerebral infarction was determined histologically in 12 coronal brain slices. There was no significant difference in CBF, OEF, or CMRO2 up to 2 h of ischemia. A high CBF with a low OEF tended to be suppressed after reperfusion in LEH-treated monkeys. Three hours after reperfusion, the area of mild CMRO2 reduction (down to -30%) decreased (P < 0.05) and the area of mild CMRO2 increase (up to 30%) expanded in LEH-treated monkeys (P < 0.05) regardless of O2 affinity with no difference in the area of moderate-to-severe reduction (<-30%) or increase (<+30%) in CMRO2 compared to animals treated with empty liposome or saline. Distribution of CMRO2 reduction and histological damages showed that LEH mainly protected the cerebral cortex rather than basal ganglia where neuronal dendritic processes were severely lost. There was little difference between the animals treated with l-LEH or h-LEH both at 10 mL/kg or between treatment with empty liposome or saline. In conclusion, LEH was effective regardless of O2 affinity in preserving CMRO2 and in reducing the area of histological damage in the cerebral cortex, but not in basal ganglia, shortly after occlusion/reperfusion of MCA in monkey.

Effects of liposome-encapsulated hemoglobin on learning ability in tokai high-avoider rat after total brain ischemia and reperfusion.

Liposome-encapsulated hemoglobin with low O2 -affinity (l-LEH) was shown to be protective in focal brain ischemia and reperfusion (I/R) in rats and primates. We tested l-LEH in the transient whole brain ischemia in the Tokai high-avoider rat (THA), which has been selected, mated, and bred over 77 generations for a high and consistent learning ability determined by the Sidman avoidance test (SAT). Young/naïve (before SAT) and adult/parent (after SAT) THA rats underwent acute and complete four-vessel occlusion in the chest for 3 or 5 min, administration of 2 mL/kg of l-LEH, saline, or homologous washed red blood cells (RBCs), reperfusion, and resuscitation. One week later, all rats underwent SAT, open-field behavioral observation, Morris water maze tests, and morphological study. Whereas young/naïve rats treated with l-LEH retained a rapid and consistent learning curve as in nonischemic controls, THA rats treated with RBCs or saline had retarded learning response on SAT as well as reduced cellularity in the amygdala. Adult/parent rats with established memory on SAT maintained perfect achievement even after I/R. In contrast, l-LEH-treated rats showed no better performance on Morris water maze (function) or cellularity of the CA1 sector of the hippocampus (morphology) compared with the rats treated with RBCs. Although task performance on SAT and Morris water maze appeared antithetical, morphological observations corresponded to the respective functions, suggesting that l-LEH was protective only for the amygdala on SAT tasks but not for the CA1 sector of the hippocampus on spatial orientation as in our previous studies on focal brain I/R, where the cortex was preserved better than basal ganglia.

Evaluation of Driver's Brain Activity Associated with Advanced Driving Skills Such as Cornering.

Evaluating the driving ability of a vehicle is important in the development of in-vehicle systems and the training of driving skills. Driving ability has been investigated extensively in terms of recognition, judgment, and operation. However, the role of the brain in advanced driving operations within the limits of vehicle performance has not been thoroughly investigated. In this study, we perform functional magnetic resonance imaging to evaluate brain functions associated with advanced driving skills when drivers are shown a video of cornering involving a vehicle slipping sideways. Based on the results, the skilled driver group indicates broad activity in both the right and left parietal associations, right-side primary somatosensory, left-side premotor, and supplementary motor areas. Because the premotor cortex is a region involved in the execution of movement, whereas the supplementary motor cortex is a region involved in spontaneous movement, it is assumed that the skilled drivers visualized the driving operation, and that the brain functions necessary for the operation are activated. These findings indicate that drivers with high skill levels exhibit distinctive brain activities. We believe that a further understanding regarding the brains of skilled drivers will facilitate the development of in-vehicle control that incorporates high driving skills and training.

Liposome-encapsulated hemoglobin ameliorates ischemic stroke in nonhuman primates: longitudinal observation.

Liposome-encapsulated hemoglobin (LEH) is protective early after brain ischemia in rats and nonhuman primates, but it remains unclear whether the protection persists and confers any benefits beyond the acute phase of brain ischemia and reperfusion. Ten monkeys underwent middle cerebral artery occlusion, received LEH (2 mL/kg, n = 5) or saline (2 mL/kg, n = 5) 5 min later, and reperfusion 3 h later. Positron emission tomography studies were repeated for the cerebral metabolic rate of O2 (CMRO2 ) as well as glucose (CMRglc) up to 8 days after reperfusion, when the animals were euthanized for morphological studies. There was no difference in O2 metabolism until 3 h after reperfusion, when CMRO2 was significantly better preserved in the cortex, but not in basal ganglia, on Day 0 in LEH-treated monkeys. The extent of cortical infarction (saline 68 ± 10% vs. LEH 38 ± 9%, P < 0.05) and CMRO2 (mild suppression: saline 34 ± 10% vs. LEH 14 ± 4%, P < 0.05) remained significantly better preserved 8 days later, when CMRglc showed a similar pattern of cortical protection (mild suppression: saline 49 ± 15% vs. LEH 37 ± 4%, P < 0.05) in LEH-treated monkeys, together with regained body weight. Somatic weight control, morphological integrity, CMRO2 , and CMRglc were better preserved immediately, as well as 8 days after occlusion and reperfusion of the middle cerebral artery in monkeys receiving LEH early after onset of ischemia.

Liposome-encapsulated hemoglobin improves energy metabolism in skeletal muscle ischemia and reperfusion in the rat.

The effect of liposome-encapsulated hemoglobin (LEH) was tested in a rodent model of limb ischemia and reperfusion--causing local reperfusion injury and a cascade of systemic responses. Intracellular pH (pHi) and phosphocreatine (PCr)/inorganic phosphate (Pi) ratio were serially monitored using ³¹P-nuclear magnetic resonance spectroscopy with a 2-cm solenoid coil on a rodent hind limb. After baseline measurements, the right hind limb underwent ischemia for 70 min, followed 10 min later by intravenous administration of LEH (10 mL/kg, n = 6), homologous red blood cells (RBCs, n = 6), saline (n = 6), or no treatment (n = 6). Reperfusion was then observed for an additional 60 min. While pHi decreased precipitously after the onset of ischemia and even following reperfusion, LEH-treated rats had significantly milder intracellular acidosis compared with all other groups during ischemia, and after reperfusion as well throughout the observation with the saline-treated rats. In contrast, the PCr/Pi ratio decreased regardless of treatment after ischemia until reperfusion, when the ratio returned toward normal or the energy status improved only in the LEH-treated rats, while the ratio remained depressed in the control animals receiving RBC, saline, or no treatment. Morphological studies 7 days later revealed a tendency toward suppressed mononuclear cell infiltration with preservation of muscular mass and structure in the LEH-treated rats. LEH treatment after early limb ischemia appeared to improve intracellular energy metabolism and eventually preserve skeletal muscle in a rodent model of limb ischemia and reperfusion.

Liposome-encapsulated hemoglobin ameliorates tumor hypoxia and enhances radiation therapy to suppress tumor growth in mice.

We hypothesize that liposome-encapsulated hemoglobin with high O2 affinity (P5002 = 12 mm Hg, h-LEH) may increase O2 delivery to hypoxic tumors and enhance radiation therapy synergistically to suppress tumor growth. First, h-LEH (5, 10, and 20 mL/kg) was intravenously infused 30 min before radiation (20 Gy) of SCCVII tumor grown in C3H/HeN mice. Second, 10 mL/kg of h-LEH was administered 30, 60, 90, and 120 min prior to radiation to determine optimal timing. Tumor size was monitored thereafter to titrate tumor growth suppression. Third, additional mice with SCCVII tumor were infused with h-LEH or empty liposome (EL), and tumors were excised at various time points for immunohistochemical examination of h-LEH and hypoxia-inducible factor-1α (HIF-1α). h-LEH was most effective at 10 mL/kg in comparison to 5 or 20 mL/kg of h-LEH or EL. Tumor growth was most suppressed when the interval between h-LEH infusion and radiation was shortest, 30 min. As a result, 10 mL/kg of h-LEH infusion 30 min prior to radiation prolonged 5-fold tumor-growth time from 20.0 days (radiation and EL) to 26.5 days, P<0.01, synergy ratio 1.42. While human hemoglobin (h-LEH) was detected in tumors 0.5 to 24 h after administration, HIF-1α accumulation was sparse and became significantly reduced compared to controls 48 and 72 h after h-LEH infusion. h-LEH (10 mL/kg) was highly effective in enhancing radiation therapy synergistically under ambient respiration against tumor growth in mice. Decreased accumulation of HIF-1α in h-LEH-treated tumor may suggest targeted tumor oxygenation as a potential mechanism.

Differences of prefrontal cortex activity between picture-based personality tests: a near-infrared spectroscopy study.

This study reports on brain activity induced by picture-based personality tests. Near-infrared spectroscopy is a newly developed, noninvasive technology in neuroimaging that can measure brain activity through blood volume changes. We measure the prefrontal cortex (Brodmann Area 10 [BA10]) activities of adolescents during the Rorschach (1921), the Rosenzweig Picture-Frustration Study (PFS; Hayashi, 1964), and Thematic Apperception Test (TAT; Murray, 1943). BA10 showed that the PFS was left-hemisphere dominant and significantly different from the Rorschach and TAT, which showed a tendency to be right-hemisphere dominant. We believe that this tendency reflects emotion and sociality.

Change in Contralateral Muscle Blood Volume During Passive Unilateral Muscle Stretching Before and After Surgery.

OBJECTIVE: Passive muscle stretching is a common physical therapy for critically ill patients in the intensive care units. This study aimed to evaluate the effects of unilateral passive stretching of the gastrocnemius muscle (GM) before and after surgery on blood volume (BV) in the contralateral (non-stretched) GM in patients who are sedated after surgery. METHODS: We enrolled eight patients with esophageal cancer. The patients completed two sessions of passive cyclical stretching (20-s hold, 10-s release, 10 cycles) of the right GM: one before surgery (awake) and one after (under sedation). We used near-infrared spectroscopy to measure the BV in the stretched and contralateral GM. BV kinetics were compared between the ipsilateral and contralateral GM. RESULTS: In seven of the eight patients, BV in the stretched GM decreased during stretching and increased during the stretch-relaxation phase, both before and after surgery. Both before and after surgery, the change in the BV in the contralateral GM was inversely synchronized to the stretching cycle. CONCLUSIONS: Unilateral passive stretching of the GM influenced the microcirculation of the contralateral GM. The mechanism underlying the synchronous change in the BV in the contralateral GM remains to be clarified.

Gymkhana and pylon slalom driving training effects on the cerebellum structure.

To develop a suitable automobile design as per each driver's characteristics and state, it is important to understand the brain function in acquiring driving skills. Reportedly, the brain structures of professionals, such as athletes and musicians, and those who have received training in special skills, undergo changes with training. However, the development process of the brain in terms of acquiring driving skills has not yet been clarified. In this study, we evaluated the effects of driving training on the brain and observed an increase in the volume of the right cerebellum after short-term training (3 days). The right cerebellum is responsible for controlling the right hand and right foot, which are important for driving. Drivers train to control a vehicle smoothly at high speeds at gymkhana and pylon slalom courses, which are often used in motor sports. The brain structure was analyzed before and after training using magnetic resonance imaging. Voxel-based morphometry was used to assess possible structural changes. First, the lap times after training were clearly shortened and vehicle dynamics were more stable, indicating that the drivers' skill level clearly improved. Second, brain structural analysis revealed a volumetric increase in the right cerebellum. The cerebellum is involved in the process of learning sensory motor skills, such as smooth steering and pedal operations, driving course shape, and vehicle size perception. These results suggest a new inner model for driving operation and support the hypothesis that motor learning affects the cerebellum during vehicle driving training.

Liposome-encapsulated hemoglobin ameliorates ischemic stroke in nonhuman primates: an acute study.

An artificial oxygen carrier, liposome-encapsulated hemoglobin (LEH), protective in a rodent stroke model, was quantitatively evaluated in monkeys. Serial positron emission tomography studies using the steady-state (15)O-gas inhalation method were performed to quantify O(2) metabolism, which was compared based on the infarction extent and immunohistochemical evaluation in 19 monkeys undergoing middle cerebral artery occlusion (3 h), infusion of various LEH doses (n = 11), empty liposome (n = 4), or saline (n = 4) 5 min after the onset of ischemia, and reperfusion for 5 h. There was no significant difference in O(2) metabolism until 3 h after reperfusion, when the cerebral metabolic rate of O(2) (CMRO(2)) was significantly less suppressed in the cortex [mild suppression in CMRO(2) (71-100%) of preischemic ipsilateral control as in the ischemic penumbra: 64.7 +/- 14.3% in empty liposome versus 32.4 +/- 7.9% in LEH (2 ml/kg) treatment, P < 0.05] but not in basal ganglia. Immunohistochemical studies showed a reciprocal expression of microtubular-associated protein II expression in the cortex and LEH deposition in basal ganglia, suggesting the LEH perfusion, but not deposition, afforded the protection. Dose-response studies revealed that as little as 0.4 ml/kg LEH (24 mg/kg hemoglobin) was effective in preserving CMRO(2), whereas 2 and 10 ml/kg were protective in significantly reducing the area of infarction as well, by 66 and 56%, respectively, compared with animals receiving saline. CMRO(2) and histological integrity were better preserved early after 3-h occlusion and reperfusion of the middle cerebral artery of monkeys receiving LEH early after onset of ischemia.

Liposome-encapsulated hemoglobin reduces the size of cerebral infarction in rats: effect of oxygen affinity.

Liposome-encapsulated hemoglobin (LEH) with a low oxygen affinity (l-LEH, P(50) = 45 mm Hg) was found to be protective in the rodent and primate models of ischemic stroke. This study investigated the role of LEH with a high O(2) affinity (h-LEH, P(50) = 10 mm Hg) in its protective effect on brain ischemia. The extent of cerebral infarction was determined 24 h after photochemically induced thrombosis of the middle cerebral artery from the integrated area of infarction detected by triphenyltetrazolium chloride staining in rats receiving various doses of h-LEH as well as l-LEH. Both h-LEH and l-LEH significantly reduced the extent of cortical infarction. h-LEH remained protective at a lower concentration (minimal effective dose [MED]: 0.08 mL/kg) than l-LEH (MED: 2 mL/kg) in the cortex. h-LEH reduced the infarction extent in basal ganglia as well (MED: 0.4 mL/kg), whereas l-LEH provided no significant protection. h-LEH provided better protection than l-LEH. The protective effect of both high- and low-affinity LEH may suggest the importance of its small particle size (230 nm) as compared to red blood cells. The superiority of h-LEH over l-LEH supports an optimal O(2) delivery to the ischemic penumbra as the mechanism of action in protecting against brain ischemia and reperfusion.

Liposome-encapsulated hemoglobin alleviates brain edema after permanent occlusion of the middle cerebral artery in rats.

Liposome-encapsulated hemoglobin (LEH) was proven to be protective in cerebral ischemia/reperfusion injury. The present study evaluated LEH in a rat model of permanent middle cerebral artery (MCA) occlusion to clarify its effect during ischemia and reperfusion. Five minutes after thread occlusion of the MCA, rats were infused with 10 mL/kg of LEH (LEH, n = 13), and compared with normal controls (n = 11). Additional animals received the same MCA occlusion with no treatment (CT, n = 11), saline (saline, n = 10), empty liposome solution (EL, n = 13), or washed red blood cells (RBC, n = 7). Severity of brain edema was determined 24 h later by signal strength in T2-weighted magnetic resonance imaging of the cortex, striatum, hippocampus, and pyriform lobe. The results showed that brain edema/infarction observed in any vehicle-infused control was significantly more severe than in LEH-treated rats. There was a tendency toward aggravated edema in rats receiving ELs. LEH infusion at a dose of 10 mL/kg significantly reduced edema formation as compared to other treatments in a wide area of the brain 24 h after permanent occlusion of the MCA. Low oncotic pressure of EL and LEH solution (vehicle solution) appeared to cause nonsignificant aggravation of edema and reduced protective effects of LEH.

S-nitrosylated pegylated hemoglobin reduces the size of cerebral infarction in rats.

Cell-free hemoglobin-based oxygen carriers have well-documented safety and efficacy problems such as nitric oxide (NO) scavenging and extravasation that preclude clinical use. To counteract these effects, we developed S-nitrosylated pegylated hemoglobin (SNO-PEG-Hb, P(50) = 12 mm Hg) and tested it in a brain ischemia and reperfusion model. Neurological function and extent of cerebral infarction was determined 24 h after photochemically induced thrombosis of the middle cerebral artery in the rat. Infarction extent was determined from the integrated area in the cortex and basal ganglia detected by triphenyltetrazolium chloride staining in rats receiving various doses of SNO-PEG-Hb (2, 0.4, and 0.08 mL/kg) and compared with rats receiving pegylated hemoglobin without S-nitrosylation (PEG-Hb) or saline of the same dosage. Results indicated that successive dilution revealed SNO-PEG-Hb but not PEG-Hb to be effective in reducing the size of cortical infarction but not neurological function at a dose of 0.4 mL/kg. In conclusion, SNO-PEG-Hb in a dose of 0.4 mL/kg (Hb 24 mg/kg) showed to be most effective in reducing the size of cortical infarction, however, without functional improvement.

Deoxygenated hemoglobin/myoglobin kinetics of forearm muscles from rest to exercise in patients with chronic obstructive pulmonary disease.

Exercise capacity is frequently decreased in patients with chronic obstructive pulmonary disease (COPD), and muscle dysfunction is one factor in this reduction. Studies using (31)-phosphorus magnetic resonance spectroscopy ((31)P-MRS) have shown that phosphocreatine (PCr) and muscle pH (pHi) are significantly decreased in patients with COPD during mild exercise, suggesting the early activation of anaerobic glycolysis in their muscles. Thus, muscle oxygenation states during exercise might differ between patients with COPD and healthy individuals. We simultaneously measured oxygenation state and pHi in the muscles of patients with COPD during the transition from rest to exercise (on-transition) using near infrared spectroscopy (NIRS) and (31)P-MRS. Sixteen patients with COPD (aged 68.6 +/- 7.5 years) and 7 healthy males (controls; aged 63.3 +/- 7.5 years) performed dynamic handgrip exercise (lifting a weight by gripping at a rate of 20 grips per min for 3 min). Patients were classified based on pHi data at the completion of exercise as having a normal (>or= 6.9; n = 8) or a low (< 6.9; n = 8) pHi. The deoxygenated hemoglobin/myoglobin (deoxy-Hb/Mb) in NIRS recordings remained constant or slightly decreased initially (time delay), then increased to reach a plateau. We calculated the time delay and the time constant of deoxy-Hb/Mb kinetics during the on-transition. The time delay was shorter in the group with a low pHi than in the controls. These findings might reflect a slower increase in O(2) delivery in patients with a low pHi, which might partly account for altered muscle energy metabolism.

Objective Ocular Discomfort: Noninvasive Evaluation by Functional Near-Infrared Ray Spectroscopy.

Purpose: Patients express their discomfort by subjective complaints, which may not clearly express the extent of their discomfort. This study noninvasively and objectively quantified ocular discomfort, a form of feeling, from the prefrontal cortex by functional near-infrared ray spectroscopy topography. Methods: This case-controlled study enrolled six dry eye patients (male:female, 1:1; 51.8 ± 15.9 years) with ocular discomfort and six normal controls (male:female, 1:1; 48.8 ± 15.2 years). Ocular discomfort was created by Schirmer 1 test in normal controls. The extent of prefrontal cortex activity was evaluated as the number of signal-positive channels using the system by using an eye-opening task with spontaneous blinking in the dark. Changes in the signal-positive channels count by lubricant or anesthetics instillation were analyzed. Results: Low prefrontal cortex activation was detected in normal controls without ocular discomfort, and high activation was detected in both normal controls and dry eye with ocular discomfort. Prefrontal cortex activity was confirmed with ocular discomfort when the eyes were open, decreased with lubricant, and almost disappeared with anesthetic for all participants. Conclusions: These changes in the prefrontal cortex activity exhibited a significant correlation to subjective complaint scores, suggesting that such discomfort may be objectively quantifiable, independent of subjective expressions.

Liposome-encapsulated hemoglobin reduces the size of cerebral infarction in the rat: evaluation with photochemically induced thrombosis of the middle cerebral artery.

BACKGROUND AND PURPOSE: Liposome-encapsulated hemoglobin (LEH; TRM-645) is a novel oxygen (O(2)) carrier with a lower O(2) affinity (P(50)O(2)=40 mm Hg) than red blood cells. In contrast to cell-free hemoglobin, encapsulation prevents hemoglobin extravasation, whereas its subcellular size (230 nm) may improve O(2) delivery and limit the severity of cerebral infarction. METHODS: The extent of cerebral infarction was determined 24 hours after photochemically induced thrombosis of the middle cerebral artery from the integrated area of infarction detected by triphenyltetrazolium chloride staining in rats receiving no treatment, 10 mL/kg of LEH, homologous blood, empty liposomes, or saline. To develop a dose-response relationship, LEH dose was reduced from 10 mL/kg to 2 mL/kg, 0.4 mL/kg, and 0.08 mL/kg. RESULTS: Infarction extent was significantly suppressed in rats receiving LEH as compared with animals receiving no infusion, saline, empty liposome, or transfusion in the cortex but not in the basal ganglia, where all had similar degrees of damage. The dose-response relationship revealed that as little as 2 mL/kg of LEH was protective, whereas the total blood O(2) content, hemoglobin level, and transfusion and/or infusion of empty liposomes or saline were not effective. CONCLUSIONS: Our results suggest that LEH significantly reduces the area of infarction in the cortex but not in basal ganglia after photochemically induced thrombosis of the middle cerebral artery in the rat.

Significant relationship between platelet activation and intra-media thickness of the carotid artery in patients with ischemic cerebrovascular disease.

INTRODUCTION: We have studied the relationship between the ratio of activated platelets and the thickness of intima and media of the carotid artery in ischemic CVD patients in the chronic stage. METHODS: Platelet activation was assessed by means of flow cytometry of whole blood using activation-dependent monoclonal antibodies (MoAb). Forty-one MRI-proven normative subjects and 55 patients with a history of ischemic CVD were examined. The intima-media thickness of the carotid artery was measured by using B-mode ultrasound in all subjects. RESULTS: The appearance rates of PAC-1-positive and CD62P-positive platelets (%) were increased in ischemic CVD patients compared with those in controls (p<0.0001, p<0.001, respectively) The patients and controls were divided into those with atherosclerosis (Ath+), defined as intima-media thickness 1.1 mm, and those without (Ath-). There was no significant difference of PAC-1-positive platelets between the Ath- and Ath+ subgroups in either group, but there was increase in Ath- ischemic CVD patients versus Ath- control subjects (p<0.01), and in Ath+ patients versus Ath+ controls (p<0.05). CD62-positive platelets in the Ath+ subgroup were significantly increased versus the Ath- subgroup in both the controls (p<0.001) and ischemic CVD patients (p<0.05), and there was also an increase in Ath- patients versus Ath- controls (p<0.05). CONCLUSION: Platelet activation markers were increased in patients with ischemic CVD compared with controls. A significant relationship was found between increased CD62-P-positive platelets and carotid artery abnormalities in both controls and ischemic CVD patients, suggesting that platelet activation may be a potential marker for atherosclerosis.

Scholastic Achievements: Graduate-entry vs. School-leaver-entry Medical Students.

OBJECTIVE: The objective of the present study is to conduct a retrospective analysis comparing graduate-entry program (GEP) and school-leaver-entry program (SEP) students from the perspective of scholastic achievements from admission through the national examination for medical practitioners. METHODS: The number of students who repeated one or more years, because of their poor results on examinations, the scores of graduation examinations, and the pass rates for the national examination for medical practitioners were compared, retrospectively, over the last 8 academic years between GEP and SEP students at Tokai University School of Medicine. RESULTS: The ratio of students who graduated in the prescribed course length was significantly higher (p = 0.002) in GEP students than that in SEP students. There were no differences between the average scores on the graduation examinations for GEP and SEP students, except in two academic years. The pass rate of GEP students (97%) of the national examination for medical practitioners was significantly higher (p < 0.001) than that of SEP students (89%). CONCLUSIONS: These results suggest that GEP students are more favorable candidates in terms of becoming physicians in the usualprescribed number of years than SEP students.

Re-evaluation of tropicamide in the pupillary response test for Alzheimer's disease.

In 1994, a pupillary response test using very dilute (0.01%) tropicamide, a cholinergic antagonist, evoked remarkable pupil dilation in subjects with Alzheimer's disease (AD) and has since been considered a diagnostic tool for AD. However, since this test was first reported, there have been studies suggesting it cannot provide a differential diagnosis of AD. Thus, the present study re-evaluated the pupillary dilation of AD (n=17) and non-AD (n=20) subjects at a 0.01% concentration of tropicamide and found that non-AD subjects, including young subjects, showed the same extent of pupil dilation as AD subjects. Furthermore, there was no significant difference between the average dilation rate of the two groups (P>0.05). When the tropicamide concentration was diluted to half of the initial concentration and performed for AD (n=14), vascular dementia (VD) (n=14), and young (n=16) subjects, the AD subjects showed a large dilation (mean pupil dilation rate: 133.8+/-15%) while the non-AD subjects did not show hypersensitivity to the new concentration of eye drops (105.4+/-9%). These differences in pupillary dilation between AD and non-AD patients were statistically significant (P<0.001). Based on these results, the most effective cutoff point of 0.005% tropicamide for differential diagnosis was 114.5% of the average pupil dilation rate for 60 min.