Association of Nutritional Indices With Adverse Effects and Time-to-Treatment-Failure in Triple Therapy for Lung Cancer

BACKGROUND/AIM

Recent lung cancer treatments include an immune checkpoint inhibitor (ICI) pembrolizumab, platinum-based agents, plus an additional cytotoxic anticancer agent. Nutritional indices, such as the geriatric nutritional risk index (GNRI) and the prognostic nutritional index (PNI), are known to correlate with the prognosis of cancer chemotherapy. Several previous studies have investigated the relationship between PNI and treatment response in non-small cell lung cancer patients, reporting significantly increased OS and PFS in the high PNI group before treatment. However, the relationship between the three-drug combination and GNRI/PNI is unclear. The current study aimed to investigate the association of nutritional indices with duration of treatment success and occurrence of side effects in triple therapy.

PATIENTS AND METHODS

Seventy-two patients with non-small cell lung cancer, treated with combination of carboplatin, pemetrexed, and pembrolizumab from November 2019 to September 30, 2022, were classified into two groups (High and Low) for GNRI and PNI, and a retrospective study was performed.

RESULTS

In terms of time-to-treatment-failure (TTF), univariate and multivariate Cox proportional hazards regression analysis showed the Low-PNI group to have significantly shorter TTF than the High-PNI group (p=0.006); multivariate analysis results also showed PNI as a factor affecting TTF (HR=2.791, 95%CI=1.362-5.721, p=0.005). On the other hand, GNRI was not shown to be a factor affecting TTF.

CONCLUSION

PNI at the start of treatment was an independent prognostic factor affecting treatment success time (TTF) in non-small cell lung cancer patients receiving triple therapy. However, PNI was not shown to be a prognostic predictor of irAE development.

Effect of Different Approaches to Antimicrobial Therapy with Cefmetazole and Meropenem on the Time to Defervescence in Non-Severe Extended-Spectrum β-Lactamase-Producing Escherichia coli Bacteremia

Carbapenems are antimicrobial agents commonly used to treat extended-spectrum β-lactamase (ESBL)-producing bacteria. Although cefmetazole (CMZ) is considered effective for ESBL-producing Escherichia coli (ESBL-EC) bacteremia, previous studies showed its limitations, including the influence of the initial antimicrobial agent. Here, we examined the effects of different approaches to antimicrobial therapy with CMZ and meropenem (MEPM) on the time to defervescence in ESBL-EC bacteremia. Notably, the influence of previous antimicrobial agents was excluded. Inpatients with ESBL-EC detected in blood cultures between April 2018 and March 2023 were included and assigned to CMZ (n = 14), MEPM (n = 8), de-escalation to CMZ (dCMZ; n = 9), or escalation to MEPM (eMEPM; n = 11) groups. The median time to defervescence was 3.5, 1.0, 2.0, and 4.0 days in the CMZ, MEPM, dCMZ, and eMEPM groups, respectively, with no significant differences. Cox proportional hazards analysis showed a significant difference in the hazard ratio (95% confidence interval) of 0.378 (0.145-0.984) for the time to defervescence with CMZ versus MEPM (p = 0.046). The extent of a delayed time to defervescence is greater with early CMZ administration than with MEPM administration in patients with non-severe ESBL-EC bacteremia.

Case Report: Case series: association between blood concentration and side effects of sotorasib

Introduction

Sotorasib is a crucial therapeutic agent for patients with non-small cell lung cancer (NSCLC) harboring the KRAS p.G12C mutation. Despite its efficacy, the relationship between blood sotorasib concentrations and side effects remains largely unexplored.

Methods

This study enrolled five patients with KRAS p.G12C-positive NSCLC treated with sotorasib (LUMAKRAS® Tablets, Amgen, Japan) between July 2022 and February 2023 at Asahikawa Medical University Hospital. Blood sotorasib levels were monitored, and their association with adverse events was examined, with no adjustments made to drug dosages based on these levels.

Results

Variable blood sotorasib levels were observed among the participants. Notably, one patient developed interstitial pneumonitis, although a definitive attribution to sotorasib was uncertain due to prior pembrolizumab treatment. The study revealed no consistent association between blood sotorasib levels and adverse events or therapeutic outcomes, with some patients experiencing severe side effects at higher concentrations, while others did not.

Conclusion

Preliminary findings suggested that monitoring blood sotorasib levels may aid in anticipating adverse events in this small cohort. However, future studies with larger sample sizes and extended follow-up periods are required to validate these initial observations. Such studies could potentially offer insights into personalized dosing strategies, thereby mitigating adverse effects and enhance patient care for individuals with KRAS p.G12C-positive NSCLC.

The Relationship Between Efficacy and Safety of Osimertinib Blood Concentration in Patients With EGFR Mutation-positive Lung Cancer: A Prospective Observational Study

BACKGROUND/AIM

Osimertinib blood levels and their impact on treatment continuation in patients with EGFR mutation-positive lung cancer is not known. This study investigated the drug blood levels and risk factors affecting treatment continuation.

PATIENTS AND METHODS

Fifty-six patients with recurrent and inoperable epidermal growth factor receptor (EGFR) mutation-positive non-small cell lung cancer who received Osimertinib (80 mg once daily, daily dose) between October 1, 2016, and August 31, 2021, were included. Patients were classified into two groups using a cutoff blood level of 155 ng/ml. The primary endpoint was the relationship between Osimertinib exposure and efficacy, and secondary endpoints were the relationship between Osimertinib exposure and side effects, and the effect of covariates on efficacy and blood levels.

RESULTS

The median progression-free survival (PFS) for evaluable patients in the steady-state trough concentration (Cmin ss) ≥155 ng/ml and Cmin ss <155 ng/ml groups was 18.7 months and 31.2 months. Serum albumin (Alb) levels were 3.73±0.40 g/dl and 3.93±0.28 g/dl (p=0.030), respectively, and in multivariate analysis, Alb <3.7 g/dl was associated with a hazard ratio of 5.304 (95%CI=1.431-19.66; p=0.013), indicating that Alb <3.7 g/dl significantly shortened PFS.

CONCLUSION

Free blood concentration of Osimertinib may have been increased by a combination of factors, including decreased hepatic metabolic function and decreased albumin production caused by systemic inflammation in patients with cancer. However, there was no effect of Osimertinib Cmin ss on PFS.

The Effect of Concomitant Usage of Analgesics on Immune Checkpoint Inhibitor-related Interstitial Lung Disease

BACKGROUND/AIM

Interstitial lung disease (ILD) is a serious adverse event (AE) associated with the use of immune checkpoint inhibitors (ICIs). However, the risk factors for developing ICI-related ILD remain poorly understood. Therefore, this study investigated the effect of concomitant analgesics on developing ICI-related ILD using the Japanese Adverse Drug Event Report (JADER) database.

PATIENTS AND METHODS

All the reported AE data were downloaded from the Pharmaceuticals and Medical Devices Agency website, and the JADER data between January 2014 and March 2021 were analysed. The relationship between ICI-related ILD and concomitant use of analgesics was assessed using reporting odds ratio (ROR) and 95% confidence interval. We investigated whether the effect of developing ILD varied according to the type of analgesics used during ICI treatment.

RESULTS

Positive signals for ICI-related ILD development were detected for the concomitant use of the narcotic analgesics codeine, fentanyl and oxycodone, but not with morphine. In contrast, there were no positive signals for the concomitant use of the non-narcotic analgesics celecoxib, acetaminophen, loxoprofen and tramadol. An increased ROR for ICI-related ILD in cases with concomitant use of narcotic analgesics was observed in a multivariate logistic analysis adjusted by sex and age.

CONCLUSION

These results suggest that the concomitant use of narcotic analgesics is involved in the development of ICI-related ILD.

Low concentrations of clarithromycin upregulate cellular antioxidant enzymes and phosphorylation of extracellular signal-regulated kinase in human small airway epithelial cells

BACKGROUND

It is well known that low-dose, long-term macrolide therapy is effective against chronic inflammatory airway diseases. Oxidative stress is considered to be a key pathogenesis factor in those diseases. However, the mechanism of action of low-dose, long-term macrolide therapy remains unclear. We have reported that clarithromycin (CAM), which is a representative macrolide antibiotic, could inhibit hydrogen peroxide (H2O2)-induced reduction of the glutathione (GSH)/glutathione disulfide (GSSG) ratio in human small airway epithelial cells (SAECs), via the maintenance of GSH levels through an effect on γ-glutamylcysteine synthetase (γ-GCS) expression. In this study, we examined the influence of CAM against H2O2-induced activities of cellular antioxidant enzymes and phosphorylated extracellular signal regulatory kinase (p-ERK) using SAECs, the main cells involved in chronic airway inflammatory diseases.

METHODS

SAECs were pretreated with CAM (1, 5, and 10 μM) for 72 h, and subsequently exposed to H2O2 (100 μM) for 0.5-2 h. Levels of GSH and GSSG, and activities of glutathione peroxidase (GPx)-1, glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT), heme oxygenase (HO)-1 and p-ERK were assayed. mRNA expressions of GPx-1 and HO-1 were measured using the real-time reverse transcription polymerase chain reaction (RT-PCR). Tukey's multiple comparison test was used for analysis of statistical significance.

RESULTS

Pretreatment with low-dose (1 and 5 μM) CAM for 72 h inhibited H2O2-induced reductions of GPx-1, GR, SOD, CAT and HO-1 activities, and mRNA expressions of GPx-1 and HO-1, and improved the GSH/GSSG ratio. However, these alterations were not observed after pretreatment with high-dose (10 μM) CAM, which suppressed phosphorylation of cell proliferation-associated ERK to cause a significant (p < 0.01) decrease in cell viability.

CONCLUSIONS

CAM is efficacious against deterioration of cellular antioxidant enzyme activity caused by oxidative stress under low-dose, long-term treatment conditions. On the other hand, pretreatment with high-dose CAM suppressed phosphorylation of cell proliferation-associated ERK and decreased cell viability. The present study may provide additional evidence as to why low-dose, long-term administration of macrolides is effective for treating chronic inflammatory airway diseases.

Long-term treatment of clarithromycin at a low concentration improves hydrogen peroxide-induced oxidant/antioxidant imbalance in human small airway epithelial cells by increasing Nrf2 mRNA expression

Background

Clarithromycin (CAM), a representative macrolide antibiotic, has been used widely at low doses for long-term therapy of chronic inflammatory airway diseases. Anti-inflammatory effects of macrolide antibiotics were first discovered in clinical practice. Although oxidative stress is known as a key pathogenesis factor in chronic airway inflammatory diseases, the mechanism of action of low-dose, long-term CAM therapy remains unclear. We aimed to examine the cytoprotective action of CAM against hydrogen peroxide (H₂O₂)-induced cell dysfunction, focusing on CAM dose and treatment duration, and using human small airway epithelial cells (SAECs), the main cells involved in chronic airway inflammatory diseases.

Methods

SAECs were pretreated with CAM (1, 5 or 10 μM) for 24, 48 or 72 h, and were subsequently exposed to H₂O₂ for 0.5–4 h. Levels of interleukin (IL)-8, glutathione (GSH) and glutathione disulfide (GSSG), and the activities of nuclear factor (NF)-κB and γ-glutamylcysteine synthetase (γ-GCS) were assayed using specific methods. IL-8 mRNA and NF erythroid 2-related factor 2 (Nrf2) mRNA expression were measured using real-time reverse transcription polymerase chain reaction (RT-PCR). Tukey’s multiple comparison test was used for analysis of statistical significance.

Results

Pretreatment with low-dose (1 or 5 μM), long-term (72 h) CAM inhibited H₂O₂-induced IL-8 levels, NF-κB activity, and IL-8 mRNA expression, and improved the GSH/GSSG ratio via the maintenance of γ-GCS expression levels. Similar to its enhancing effect on the GSH/GSSG ratio, pretreatment with low-dose CAM for 72 h significantly increased Nrf2 mRNA expression (p < 0.01 and p < 0.05). In contrast, these alterations were not observed after pretreatment with high-dose (10 μM) or short-term (24 and 48 h) CAM.

Conclusions

CAM is efficacious against cell dysfunction caused by oxidative stress under low-dose, long-term treatment conditions. This effect depended on the suppression of NF-κB activation and improvement of the H₂O₂-induced oxidant/antioxidant imbalance that is achieved by increasing Nrf2 mRNA expression in SAECs. The present study may provide the first evidence of why low-dose, long-term administration of macrolides is effective for treating chronic inflammatory airway diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s40360-017-0119-8) contains supplementary material, which is available to authorized users.

Neonatal sucking behaviour and its development until 14 months

A fiberscope supported by a holder, devised by one of the authors, was used to film neonatal sucking behaviour and its development from birth to 14 months of life. The subjects were 57 low-risk full term infants. Present observations detect a developmental course of the sucking behaviour. The main changes are: (a) the bell shape produced by the peristaltic tongue movements is quite high in the neonatal period, decreases in height considerably during the third month and almost disappears by the tenth month of life. (b) The depth of the cavity produced by the peristaltic tongue movements increases from the third month until the eighth month and decreases after this time, (c) The wrapping by the root of the tongue at the tip of the nipple gradually weakens during the first month and almost disappears around the sixth month of life. (d) The neonatal pattern disappears and the pattern for older infants appears in one sucking episode in the same infant during the second and third month after birth. There are individual differences in the period of actual change but it usually appears during the third month.

[Sucking behavior of normal full-term and low-risk preterm infants]

The sucking behavior of infants was analyzed by taking pictures using a fiberscope. The pictures were taken from inside an artificial nipple when a baby was sucking. The recording was carried out on babies of between 38 and 40 weeks gestational age. The subjects were 20 normal full term infants and 20 low-risk preterm infants. Individual differences were found, but it was possible to abstract the common components of the sucking behavior. The main components studied were the degree of adhesiveness of the lips to the breast for forming an airtight closure, the degree to which the tongue wraps the nipple, the width of the peristaltic tongue movements, and 6 other components. Each component was measured on a 3 point scale, where 1 is poor, 2 is good and 3 is excellent. The total score for each subject was determined by adding the scores for all nine components. The overall score for each infant indicates a level of individual sucking behavior. After the scale was compiled, the level of the sucking behavior of normal full term infants and that of low-risk preterm infants were assessed. The result showed significant discrepancies between the two groups. Low-risk preterm infants had lower overall scores than normal full term infants, and this difference was seen in all nine components.

Neurones with epileptiform discharge in the central nervous system and chronic pain. Experimental and clinical investigations

Epileptiform discharge was recorded from neurons in the thalamic nuclei of chronic pain patients during stereotactic surgery. Hyperactive neurons showed regular firing of 3-5 trains of epileptic-like group discharges with a frequency of 4 to 5 Hz. As described by Lombard et al. (1979), we operated on the dorsal root unilaterally, sectioning C5 to Thl in male Wistar rats. One to three months after the operation, hyperactive neurons were examined in the contra-lateral thalamic nuclei (VP, zona incerta), and lemniscus medialis. The firing patterns and distribution of hyperactive neurons in these animals was very similar to those of humans. The hyperactive neuron was unaffected by electrical stimulation of the nucleus raphe dorsalis (NRD) and locus ceruleus (LC). Administration of phenytoin and diazepam reduced the firing. However, no effect was seen with valproic acid. During spreading depression of the sensorimotor cortex, a remarkable reduction was seen on the firing of thalamic hyperactive neurons. This suggested that hyperactive neurons of the thalamic nuclei received facilitory effects from the sensorimotor cortex with little influence from adrenergic or serotoenergic systems.

Effect of midbrain raphe nucleus stimulation on somatosensory evoked potential in cat

Experiments were carried out to clarify the effect of serotonin [5-hydroxytryptamine (5-HT)] upon the somatosensory evoked potential (SEP) elicited by superficial radial nerve stimulation in cat, and the following results were obtained: (i) in untreated (control) animals, a significant reduction occurred in amplitude of the SEP in response to conditioning stimulation of the dorsal raphe nucleus in the midbrain, within 100 ms of the interval between conditioning and test stimuli; (ii) in 5-HT depleted animals prepared by intraperitoneal injection of p-chlorophenylalanine (PCPA), the amplitude of SEP significantly increased in comparison with that of nontreated animals. Conditioning stimulation of the raphe nucleus in 5-HT depleted animals failed to cause any remarkable change in the SEP; (iii) the diminuation of the SEP by raphe nucleus conditioning reappeared following intraventricular administration of a large dose of 5-HT (200 micrograms) in the PCPA-treated animals. These results have demonstrated that the serotonergic system with its cell bodies located in the raphe nucleus of the midbrain has the function of reducing the amplitude of the SEP, thus suggesting that it acts as a suppressive control on the excitability of the cortex to sensory input.

Evoked potentials from the human thalamus: correlation with microstimulation and single unit recording

During stereotactic surgery, intrathalamic single unit recordings and summated evoked potentials (Th-SEP), evoked by percutaneous electrical median nerve stimulation and intrathalamic microstimulation, were done using the same microelectrode at the same site. Potentials evoked by natural and electrical stimulation were compared. The format of Th-SEP varied in anteroposterior, mediolateral and dorsoventral directions in the ventrocaudal nucleus (Vc). The positive response peak latency was shortest from the caudal part of Vc and longest from the anterior part of Vc.

Influence of the ipsilateral hemisphere upon somatosensory evoked potential in cats

Somatosensory evoked potentials (SEPs) were recorded on the skull corresponding to the (left) SI area by (right) superficial radial nerve stimulation. Amongst the various components of the SEP, special attention was directed to the negative component (N15) with a latency of approximately 15 ms. Changes in this potential followed by conditioning stimulation of the ipsilateral (right) hemisphere were observed and the following results were obtained: (i) when conditioning stimuli were applied to the contralateral (left) superficial radial nerve, the ipsilateral (right) thalamic VPL nucleus and the ipsilateral (right) sensory cortex, the amplitude of N15 decreased to 65-80% of the control level at C-T intervals less than 100 ms and (ii) following functional elimination of the unilateral sensory cortex by KCl application, the amplitude of N15 recorded at the opposite side significantly increased. In this condition, the inhibitory effects of the ipsilateral thalamus and contralateral peripheral nerve disappeared. From these observations, ipsilateral homologous cortex may well have an inhibitory influence upon the near field potential (N15) of the SEP.

Origin of frontal N15 component of somatosensory evoked potential in man

Origin of the frontal somatosensory evoked potential (SEP) by median nerve stimulation was investigated in normal volunteers and in patients with localized cerebrovascular diseases, and the following results were obtained. (1) In normal subjects, SEPs recorded at F3 (or F4) contralateral to the stimulating median nerve were composed of P12, N15, P18.5 and N26. Similar components were recognized in SEP recorded at Fz. (2) In patients in whom putaminal or thalamic hemorrhages had destroyed the posterior limbs of the internal capsules, frontal N15 and parietal N18 (N20) disappeared. These components were also absent in patients with cortical (parietal) infarctions. Among these patients, the thalamus was not affected in cases with putaminal hemorrhages and cortical infarctions. These facts indicate that the generator of the frontal N15 does not exist in the thalamus but that it originates from the neural structure central to the internal capsule, which suggests a similarity to the generator of the parietal N18. Because N15 was recorded in the midline of the frontal region with shorter latency than parietal N18, the frontal N15 might represent a response to the sensory input of the frontal lobe via the non-specific sensory system.

Origin of short latency somatosensory evoked potential in cats: especially potentials derived from thalamus and cortex

Short latency somatosensory evoked potential (SSEP) was recorded in cats to identify the potentials originating from the cortex and the thalamus, and the following results were obtained. When SSEP was elicited on the bregma by stimulation of the contralateral superficial radial nerve, P2, P4, P4.5, P5.5, P7, P8, N8.5, P11, P9.5, N11.5, N12.5 and N14 were recognized. Of these components N11.5, N12.5 and N14 consisted of large negative potential (LNP). When KCl was applied to the sensorimotor cortex to induce spreading depression, the positive component of the primary evoked potential was markedly decreased and the negative component disappeared. In SSEP, components preceding N8.5 were unchanged. N8.5-P11 and P11-N12.5, however, markedly diminished or disappeared. The latency of the first component of the field potential recorded in the VPL nucleus of the thalamus was about 5 ms. When a small amount of Nembutal was injected into VPL nucleus, components between P2 and P4.5 remained unchanged, but P5.5 disappeared. P7, P8 and N8.5 were preserved. The amplitude of N8.5-P11 was markedly decreased and LNP disappeared. From these results, among various components of SSEP, P5.5 should originate from the thalamus, and P7, P8 and N8.5 from the extralemniscal system. N8.5-P11 should mainly represent post-synaptic potential (PSP) in the deep somatic layer, and P11-N12.5 represent PSP in the apical dentrites of the sensorimotor cortex. N14 probably represents PSP via the diffuse projection system. Thus, LNP should consist of complex potentials of specific and non-specific sensory systems.

Origin of the initial negative potential (N15) recorded on the skull by superficial radial nerve stimulation in the cat

The origin of the initial prominent negative potential with a latency of about 15 msec (N15), recorded on the skull by superficial radial nerve stimulation was studied in the cat, and the following results were obtained. In the direct recording from the cortex, SEPs were elicited from the SI and SII areas, as well as the lateral gyrus and anterior suprasylvian gyrus. Among various wave forms recognized in the SI area, diphasic positive-negative (P-N) potential obtained from the postero-lateral part was most distinct, representing the primary evoked potential. Responses recorded on the dura and those directly on the cortex showed similar wave patterns over many sites. Although different forms of evoked potentials were recorded extensively over the skull, the most prominent negative potential was elicited at the site corresponding to the postero-lateral part of the SI area. The latency of this potential was approximately in agreement with that of the negative component of the P-N potential recorded on the cortex. Based on the intracortical laminar analysis of P-N potential, the positive component of this potential was assumed to reflect the activity of cells in the deeper layer of the cortex. The negative component, on the other hand, might represent activities of apical dendrites of the cortex. From the result of functional elimination of the cortex, however, this positive component was thought to contain potentials from far field neural structures. N15 recorded on the skull completely disappeared during cortical spreading depression.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes of somatosensory evoked potential accompanying ischaemia and hypoxia in cats

Changes of evoked potential accompanying haemorrhagic hypotension and hypoxia were investigated on cats to evaluate the usefulness of SEP as a monitor in an intensive care unit (ICU), and the following results were obtained. Positive-negative diphasic potential was elicited at posterior sigmoid gyrus(PSG) by contralateral superficial radial nerve stimulation. This potential was recorded at the restricted area of the posterior border of PSG and regarded as primary somatosensory evoked potential. In the initial stage of haemorrhagic hypotension, both positive and negative components of SEP occasionally increased in amplitude. In profound hypotension in which CBF fell to less than the critical level of 30 ml 100 g-1 min-1, the latency was retarded and the amplitude was decreased. At CBE less than 10 ml 100 g-1 min-1, SEP disappeared. Within the range of CBF between 10 and 30 ml 100 g-1 min, a close correlation was noted between CBF and SEP amplitude. Transient increase of SEP amplitude was also observed during hypoxia induced by inhalation of nitrogen gas. (3) In normal state SEP was decreased in amplitude by conditioning stimulation of the nucleus lateralis posterior (LP nucleus) of the thalamus. This might be explained by the fact that intracortical inhibitory interneurons were activated by stimulation of LP nucleus. After haemorrhagic hypotension and hypoxia, however, the inhibitory effect on SEP elicited by LP nucleus stimulation attenuated or disappeared. Because of the initial impairment of the inhibitory interneurons by ischaemia and hypoxia, the amplitude of SEP might increase transiently. In conclusion, the authors thought that SEP might be less useful than EEG in ICU, because of its insensible change to hypoxia and ischaemia.

[Surface negative waves in penicillin-induced epileptogenesis in cats]

The "surface negative (SN) wave" produced by pyramidal tract stimulation and recorded at the cortical surface has been identified as a reflection of postsynaptic potentials generated through recurrent inhibitory pathways (Humphrey, et al.). We studied changes in SN wave in an attempt to examine inhibitory mechanisms underlying epileptogenesis in immobilized cats. 1) A single shock applied to the cerebral peduncle evoked alpha and beta wave at the surface of ipsilateral anterior sigmoid gyrus (Fig.1 A). A train of 4 shocks with 4 msec shock-interval elicited SN wave which had a peak latency of 20 msec and decayed in 60-80 msec (Fig. 1 B,C,D). 2) The spindle-like after-discharges elicited by direct cortical shock were markedly suppressed with conditioning stimulation of the ipsilateral pyramidal tract (Fig. 2). Spike-and-wave complexes and other ECoG paroxysms produced by intramuscular administration of penicillin (Pc) were also depressed by repeated stimulation of the cerebral peduncle (Fig. 3). These facts revealed that the inhibitory effects of pyramidal tract stimulation caused to suppress the occurrence of epileptic discharges. 3) SN wave gradually diminished in amplitude after topical application of Pc at the anterior sigmoid gyrus (Fig. 4 A-D). It disappeared completely when tonic-clonic sustained paroxysms occurred at the focus (Fig. 4 E). These effects are due presumably to depression of recurrent postsynaptic inhibition caused by topical penicillin. 4) SN wave observed at the contralateral secondary focus was almost unchanged during interictal and ictal stage (Fig. 5).(ABSTRACT TRUNCATED AT 250 WORDS)

[Cerebral blood flow dynamics of spontaneous occlusion of the circle of Willis (Part 1)--comparison between electrophysiological findings and neuroradiological findings]

Four cases (2 children and 2 adults) of spontaneous occlusion of the circle of Willis were studied using EEG, somatosensory evoked potential (SEP), cerebral angiography and CT scan. The following results were obtained. 1) Among the above described parameters, SEP was the most useful to detect the ischemic change in the thalamus when the obstruction of the posterior part of the circle of Willis extends, even before a low density lesion of the thalamus appears on CT. 2) In child cases, a decrease in the amplitude N3 of SEP was observed after hyperventilation. It was speculated that this finding of SEP might be correlated with the mild cortical ischemia due to vasoconstriction and "rebuild up" phenomenon in EEG after hyperventilation.

[Correlation between local cerebral blood flow and EEG in experimental cerebral ischemia]

Varying degrees of cerebral ischemia were produced in adult Wistar rats by clipping of bilateral common carotid arteries with or without induced hypotension. Local cerebral blood flow was measured from bilateral caudate nuclei and parietal cortices using the hydrogen clearance method. EEG was recorded from the same electrode as used for the hydrogen clearance method. The delta power of EEG increased along with decreasing local cerebral blood flow. There was an inverse correlation between the delta power of EEG and local CBF values, ranging from normal to extremely low (10 ml/100 g/min). When local CBF was reduced below 6-8 ml/100 g/min, EEG became isoelectric. Continuous EEG recording might contribute to predict rCBF value in the ischemic lesion.

Electrical impedance as a locating method in human stereotactic surgery

During stereotactic surgery, electrical impedance was measured by means of a roving electrode technique with a sine wave current of 10 kc. Impedance showed a characteristic decrease when the electrode was passing through the thalamus and consequently the impedance profile corresponding to the thalamic area exhibited the characteristic shape of a 'frying pan'. By observing the impedance, it is possible to differentiate the thalamic gray matter from the surrounding structures with some accuracy.