Taro Wada

Ischemic "cross" tolerance in hypoxic ischemia of immature rat brain.

The phenomenon of ischemic tolerance has been closely associated with the expression of heat shock proteins but recently, stress tolerance not related to hsp72 has been reported. In the present study, we focused on ischemic tolerance induced by hypoxia and hyperthermia in neonatal rat brain and analyzed the expression of hsp72. In a neonatal rat model of hypoxic ischemia (H-I), preconditioning by whole-body hyperthermia or hypoxia was induced 24 h prior to the ischemia. Brain damage was histologically evaluated and the expressions of hsp72 were analyzed. Hyperthermic preconditioning at 41 degrees C for 15 min, as well as hypoxic preconditioning with 8% hypoxia for 3 h, had almost complete neuroprotective effects. However, we failed to detect the expression of hsp72 in any of preconditioning. Only the H-I insult itself induced hsp72 in the dorsal striatum and slightly in the thalamus and the hippocampus. Hyperthermic preconditioning has neuroprotective effects which are comparable to hypoxic preconditioning in immature brain. The expression of hsp72 is not likely necessary for the ischemic tolerance in immature brain.

TRANSCRANIAL DOPPLER FINDINGS DURING BALLOON TEST OCCLUSION OF THE INTERNAL CAROTID ARTERY

The authors performed transcranial Doppler ultrasonography (TCD) during internal carotid artery (ICA) balloon test occlusion (BTO) and observed changes in mean flow velocity (Vm) in the middle cerebral artery (MCA), and pulsatility index (PI) while monitoring the stump pressure (Sp) of the internal carotid artery (ICA), and neurologic findings. A group of 17 patients requiring possible temporary or permanent occlusion of the ICA in the course of planned procedures first underwent BTO. A patient who either developed neurologic changes or maintained less than 60% of preocclusion Sp or Vm in the ipsilateral MCA during BTO was considered to have a positive test. Eleven patients had negative results, while in six patients, tests were positive. Mean flow velocity showed a decrease after occlusion in all cases but not to a remarkable extent in some patients. Stump pressure decreased in all negative cases after balloon inflation and than tended to increase progressively during 15 minutes of BTO. Pulsatility index tended to decrease gradually during BTO in all negative patients. However, in positive cases, PI and Sp fell steeply. Only one positive case had a neurologic symptom of severe headache. The decreased PI in the MCA reflected autoregulatory dilation of cerebral vessels to compensate for decreased absolute cerebral blood volume following ICA occlusion. Changes in PI are a good indicator for evaluating blood flow during BTO.

Cross-tolerance: Hyperthermia preconditioning induces ischemic tolerance in immature rat brain.

生後7日の新生ラット低酸素負荷虚血モデルを用いた.前処置として24時間前に41℃の高温処置を加えた群, 低酸素3時間を加えた群を作成した.虚血のできた個体数は対照群, 高体温群, 低酸素群で各々19/23匹, 4/21匹, 0/8匹であり, 高体温群, 低酸素群は対照群と比べ有意に虚血障害が減少した.海馬スライスにおける非損傷面積は49.3±5.5%, 高体温群では92.5±3.8%, 低酸素群では100±0%と有意差を認めた.低酸素前処置により脳虚血耐性が獲得されたのみならず, 異なるストレスである高体温前処置でも虚血耐性が獲得された (交差耐性).

1335 Cross tolerance: Hyperthermia preconditioning induces ischemic tolerance

MASATO MATSUOKA’, YUJI MORIr, MASUMI ICHIKAWA2 The effects of urinary stimuli were studied on the dendrodendritic reciprocal synapses in the accessory olfactory bulb by examining two different synaptic complexes: asymmetrical excitatory synapses (mitral/tufted to granule cells) and symmetrical inhibitory ones (granule to mitral/tufted cells). The synapses may have important functions in the processing of pheromonal information. Adult male hamsters were divided into four groups and exposed to one of following four materials: distilled water, female hamster urine, female rat urine, and male hamster urine. After fifteen days, the length of the postsynaptic thickening was measured. The exposure to female hamster urine induced a reduction in the size of asymmetrical synapses as compared with the other three groups. There was no effect in the size of symmetrical synapses. These differential morphological changes can be ascribed to differing pheromonal components contained in each urine preparation.