The level of thyroid hormones is an important factor in determining the outcome of coronary arter... more The level of thyroid hormones is an important factor in determining the outcome of coronary artery bypass patients. Sodium nitroprusside (SNP) is a natural donor of nitric oxide which has been shown to interfere with thyroid hormone synthesis. Whether clinical use of sodium nitroprusside has any effect on thyroid function has not yet been investigated. The aim of this study was to investigate the effects of SNP administration on circulating levels of thyroid hormones. One hundred and six consecutive patients who underwent coronary artery bypass grafting operation were prospectively randomized to receive continuous infusions of either SNP or saline limited to the rewarming time of cardiopulmonary bypass (CPB). Free triiodothyronine (T3), total T3, free thyroxine (T4), total T4 and thyroid-stimulating hormone (TSH) levels were analyzed. Free T3, TSH and albumin changes of SNP and control groups were statistically different from each other. In the SNP group, free T3 values stayed in the euthyroid range between CPB and post-CPB periods, the period when SNP was infused, whereas it continued to decline to hypothyroidic levels in the control group. In addition, in the SNP group, an elevation in TSH levels was observed during the CPB period. Postoperatively, an earlier restoration of free T3 and TSH levels was observed in the SNP group when compared to the control group. In this study, administration of SNP during cardiopulmonary bypass is shown to regulate free T3 and TSH levels positively.
The aim of this experimental study was to investigate the possible protective effect of dantrolen... more The aim of this experimental study was to investigate the possible protective effect of dantrolene on neuronal injury induced by aortic ischemia/reperfusion (I/R). Nineteen rabbits were divided into three groups: sham (group 1, n = 5, no I/R), control (group 2, n = 7, only I/R) and dantrolene (group 3, n = 7, dantrolene + I/R). Abdominal aortic occlusion between the renal arteries and iliac bifurcations was carried out for 30 min. The spinal cord functions of the subjects were assessed using the Tarlov Scale. Blood and cord tissue samples were taken for biochemical and histopathological evaluation. Tarlov scores in group 3 were significantly higher than in group 2 ( P < 0.05). In group 3, the MDA levels of the spinal cord decreased significantly compared to those of group 2 ( P < 0.05). In rabbits with I/R (group 2), the GSH levels of the spinal cord decreased significantly compared to those of group 1 ( P < 0.01), but dantrolene pretreatment significantly prevented a decrease in GSH levels. Histopathological examination showed that group 3 had less vascular proliferation, hemorrhage, edema and neuron loss than group 2. It was concluded that dantrolene applied after ischemia might help protect the spinal cord against ischemia/reperfusion injury.
Selectively retrieving a subset of previously studied material can cause forgetting of the unprac... more Selectively retrieving a subset of previously studied material can cause forgetting of the unpracticed material. Such retrieval-induced forgetting is attributed to an inhibitory mechanism recruited to resolve interference among competing items. According to the inhibition-deficit hypothesis, older people experience a specific decline in inhibitory function and thus should show reduced retrieval-induced forgetting. However, the results of the two experiments reported here show the same amount of retrieval-induced forgetting in younger and older adults. These results indicate that retrieval inhibition is intact in older adults' episodic recall. The findings suggest that the common view of a general inhibitory deficit in older adults needs to be updated and that older adults show intact inhibition in some cognitive tasks and deficient inhibition in others.
In adults, selective memory retrieval can both impair and improve recall of other memories. The s... more In adults, selective memory retrieval can both impair and improve recall of other memories. The study reported here examined whether children also show these two faces of memory retrieval. Employing a variant of the directed-forgetting task, we asked second, fourth, and seventh graders to study a list of target and nontarget words. After study, the participants received a cue to either forget or continue remembering the list. We subsequently asked some participants to recall the nontarget words before we tested their memory for the target words; for the remaining participants, we tested memory only for the target words. Prior retrieval of nontarget words impaired retrieval of to-be-remembered target words, regardless of children’s age. In contrast, prior retrieval of nontarget words improved recall of to-be-forgotten target words in seventh graders, though not in fourth and second graders. These results suggest a developmental dissociation between the two faces of memory retrieval a...
The level of thyroid hormones is an important factor in determining the outcome of coronary arter... more The level of thyroid hormones is an important factor in determining the outcome of coronary artery bypass patients. Sodium nitroprusside (SNP) is a natural donor of nitric oxide which has been shown to interfere with thyroid hormone synthesis. Whether clinical use of sodium nitroprusside has any effect on thyroid function has not yet been investigated. The aim of this study was to investigate the effects of SNP administration on circulating levels of thyroid hormones. One hundred and six consecutive patients who underwent coronary artery bypass grafting operation were prospectively randomized to receive continuous infusions of either SNP or saline limited to the rewarming time of cardiopulmonary bypass (CPB). Free triiodothyronine (T3), total T3, free thyroxine (T4), total T4 and thyroid-stimulating hormone (TSH) levels were analyzed. Free T3, TSH and albumin changes of SNP and control groups were statistically different from each other. In the SNP group, free T3 values stayed in the euthyroid range between CPB and post-CPB periods, the period when SNP was infused, whereas it continued to decline to hypothyroidic levels in the control group. In addition, in the SNP group, an elevation in TSH levels was observed during the CPB period. Postoperatively, an earlier restoration of free T3 and TSH levels was observed in the SNP group when compared to the control group. In this study, administration of SNP during cardiopulmonary bypass is shown to regulate free T3 and TSH levels positively.
The aim of this experimental study was to investigate the possible protective effect of dantrolen... more The aim of this experimental study was to investigate the possible protective effect of dantrolene on neuronal injury induced by aortic ischemia/reperfusion (I/R). Nineteen rabbits were divided into three groups: sham (group 1, n = 5, no I/R), control (group 2, n = 7, only I/R) and dantrolene (group 3, n = 7, dantrolene + I/R). Abdominal aortic occlusion between the renal arteries and iliac bifurcations was carried out for 30 min. The spinal cord functions of the subjects were assessed using the Tarlov Scale. Blood and cord tissue samples were taken for biochemical and histopathological evaluation. Tarlov scores in group 3 were significantly higher than in group 2 ( P < 0.05). In group 3, the MDA levels of the spinal cord decreased significantly compared to those of group 2 ( P < 0.05). In rabbits with I/R (group 2), the GSH levels of the spinal cord decreased significantly compared to those of group 1 ( P < 0.01), but dantrolene pretreatment significantly prevented a decrease in GSH levels. Histopathological examination showed that group 3 had less vascular proliferation, hemorrhage, edema and neuron loss than group 2. It was concluded that dantrolene applied after ischemia might help protect the spinal cord against ischemia/reperfusion injury.
Selectively retrieving a subset of previously studied material can cause forgetting of the unprac... more Selectively retrieving a subset of previously studied material can cause forgetting of the unpracticed material. Such retrieval-induced forgetting is attributed to an inhibitory mechanism recruited to resolve interference among competing items. According to the inhibition-deficit hypothesis, older people experience a specific decline in inhibitory function and thus should show reduced retrieval-induced forgetting. However, the results of the two experiments reported here show the same amount of retrieval-induced forgetting in younger and older adults. These results indicate that retrieval inhibition is intact in older adults' episodic recall. The findings suggest that the common view of a general inhibitory deficit in older adults needs to be updated and that older adults show intact inhibition in some cognitive tasks and deficient inhibition in others.
In adults, selective memory retrieval can both impair and improve recall of other memories. The s... more In adults, selective memory retrieval can both impair and improve recall of other memories. The study reported here examined whether children also show these two faces of memory retrieval. Employing a variant of the directed-forgetting task, we asked second, fourth, and seventh graders to study a list of target and nontarget words. After study, the participants received a cue to either forget or continue remembering the list. We subsequently asked some participants to recall the nontarget words before we tested their memory for the target words; for the remaining participants, we tested memory only for the target words. Prior retrieval of nontarget words impaired retrieval of to-be-remembered target words, regardless of children’s age. In contrast, prior retrieval of nontarget words improved recall of to-be-forgotten target words in seventh graders, though not in fourth and second graders. These results suggest a developmental dissociation between the two faces of memory retrieval a...
Uploads
Papers