Prognostic analysis of patients with operable gastric cancer and tolerability to adjuvant radio-chemo-therapy.

The aim of this study is to evaluate the tolerability and toxicity of adjuvant chemoradiotherapy (CRT) and to analyze the prognosis in patients with operable gastric cancer. The retrospective analysis included 723 patients with operable gastric cancer; stage IB-IV (M0), received adjuvant CRT from 8 Medical Centers in Turkey between 2003 and 2010. The patients' age, sex, tumor localization, Lauren classification, grade and stage of the disease, type of dissection, the toxicity and tolerability status and survival rate were analyzed. All patients were divided into two groups as tolerable group to adjuvant CRT and intolerable group to adjuvant CRT .Among the patient, 73.9% had stage III-IVM0 disease; 61.0% had the intestinal type of gastric cancer, 51.1% had the distal type, and 61.4% had undergone D2 dissections. The number of patients who completed the entire course of the adjuvant CRT was 545 (75.4%).The median follow-up period was 20.8 months (range: 1.5-107 months). Overall Survival (OS) rates were 80% and 52%, while the relapse free survival (RFS) rates were 75% and 48% at 1 and 3 years, respectively.In the univariate analysis of the groups based on the the age defined as <65 or ≥ 65 (p=0.16 / p=0.003), Lauren classification (p=0.004 / p<0.001), localization of tumor (p=0.02 / p=0.04), tumor grade (p=0.06 / p=0.003), disease stage (p<0.001 / p<0.001), type of dissection (p=0.445 / p=0.043), presence or absence of toxicity (p=0.062 / p=0.077) and tolerability of the therapy (p=0.002 / p=0.001). In the cox regression analysis, tumor stage (Hazard Ratio (HR): 0.332; 95% confidence interval (CI): 0.195-0.566; p<0.001), and tolerability (HR: 0.516; 95% CI: 0.305-0.872; p=0.014), were found to be related with the OS. Tumor stage (HR: 0.318; 95% CI: 0.190-0.533; p=<0.001) and tolerability (HR: 0.604; 95% CI: 0.367-0.995; p=0.048) were observed to be statistically significant in terms of the RFS.We have observed that whether a patient can or cannot tolerate adjuvant CRT due to its toxicity is an independent prognostic factor besides the known prognostic factors like tumor stage and Lauren classification. We are of the opinion that the treatment of patients who cannot tolerate adjuvant CRT should be replaced with less toxic adjuvant therapies.

Local differences in the position of the mental foramen.

The mental foramen has been reported to vary in position in different ethnic groups. Repeated failures during injections and operative procedures involving the mental foramen suggest the presence of local differences in a given population. The aim of the present study was to investigate possible local differences of the mental foramen in Eastern Anatolian individuals in the Turkish population. The present investigation is based on the examination of 70 adult mandibles. The study consisted of three measurements, to include the relations of the mental foramen to the following: 1) the lower teeth; 2) the body of mandible; 3) the mandibular symphysis and posterior border of the ramus of the mandible. The most common position of the foramen was in line with the longitudinal axis of the second premolar tooth (relation IV), at the midpoint of the mandibular body height and at 1/3.5 of the distance from the mandibular symphysis to the posterior border of the ramus. Local differences of the mental foramen may occur in a population. Prior to surgery knowledge of the most common location of the foramen peculiar to a local population may enable effective mental block anaesthesia to be provided.

Electroencephalogram alpha (8-15 Hz) responses to visual stimuli in cat cortex, thalamus, and hippocampus: a distributed alpha network?

To investigate possible functional correlates of alpha (8-15 Hz) oscillations in the electroencephalogram (EEG) intracranial recordings in cats (from thalamus, occipital cortex, and hippocampus) were performed. In response to visual stimuli, event-related alpha oscillations were observed. Such alpha responses were found not only in a specific sensory (visual) pathway but also in the hippocampus, hinting at a possible distributed alpha response system.

Evoked EEG alpha oscillations in the cat brain--a correlate of primary sensory processing?

Event-related alpha (10 Hz) oscillations in the EEG were measured in cats by means of intracranial electrodes. Simultaneous recordings were made from auditory and visual cortex while auditory and visual stimuli were applied (in separate sessions). Frequency domain analysis of the EEG responses showed marked alpha components only for adequate stimulation (e.g. visual cortex-visual stimulus). This hints at a functional relationship between alpha responses and primary sensory processing.

A possible role of evoked alpha in primary sensory processing: common properties of cat intracranial recordings and human EEG and MEG.

Regarding the evoked potential (EP) as a superposition of evoked EEG rhythms in several frequency ranges, we investigated the following issue: Are distinct evoked rhythms, in particular the alpha (8-15 Hz) response, related to separable physiological processes? Frequency domain analysis of EPs was used to evaluate results of cross-modality experiments, i.e.: responses to auditory stimuli were simultaneously recorded from the auditory cortex (adequate stimulation) and from the visual cortex (inadequate stimulation). Responses to visual stimuli were recorded from the same sites. The results of these experiments and further measurements (EEG and MEG responses in humans, among them multiple sclerosis patients) are consistent in the following respect: The amplitudes of alpha responses are dependent on whether or not a stimulus applied is adequate. Alpha responses may thus be related mostly to primary sensory processing. In contrast, theta responses (4-7 Hz) were observed for adequate as well as inadequate stimuli. They may be related rather to associative and cognitive processing than to primary sensory processing. Thus frequency responses, in particular the alpha response, are not artificial results of digital filtering, but functionally significant brain responses.

Event-related theta rhythms in cat hippocampus and prefrontal cortex during an omitted stimulus paradigm.

In a recent study on human subjects which performed a time prediction task in an omitted stimulus paradigm we found an increase in the amplitudes of evoked potentials (EPs) for the stimulus preceding the omitted stimuli, probably due to expectancy and focused attention. The amplitude increases were dominant over frontal and parietal association areas and were mainly reflected in enhancements of the theta (3-6 Hz) components. In the present study we analyse the responses of the auditory cortex (GEA, gyrus ectosylvianus anterior), different parts of hippocampus (CA1, CA3), reticular formation (RF), and motor cortex (MC) of the cat brain using a similar paradigm. Similar theta component increases of the EPs were obtained in various parts of the hippocampus, which were dominant in pyramidal cell layers (CA3, CA4), and in motor cortex. The results are interpreted as signs of a diffuse theta response system in the brain including mainly the hippocampus and frontal and parietal association areas. The diffuse theta system is probably involved in general attention and expectancy processes.

Auditory evoked potentials in multiple sclerosis: alpha responses are reduced in amplitude, but theta responses are not altered.

Auditory evoked potentials (EPs) were measured in a group of 16 multiple sclerosis (MS) patients and in a control group of 20 subjects. In vertex recordings, response amplitudes were reduced in the MS group. Remarkably, EP frequency components computed from the averaged EPs showed different degrees of amplitude reduction in different frequency channels: alpha (7-12 Hz) components were reduced whereas theta (4-7 Hz) responses were not altered. Our interpretation takes into account results of our companion paper (Basar-Eroglu et al., this issue) on similar results in the visual modality and is based on considering MS as a disease with disturbed sensory input to the brain. The fact that in this disorder alpha responses are reduced while theta responses are not altered can be interpreted as follows: alpha components might be mainly dependent on sensory input and thus reflect primary sensory processing. Theta responses, being unaltered in MS, might mainly reflect associative processing. The results are in accordance with conclusions drawn from investigations of topographic differences of evoked electric and magnetic brain responses.

Sensory and cognitive components of brain resonance responses. An analysis of responsiveness in human and cat brain upon visual and auditory stimulation.

We performed an analysis of topographic and modality-dependent responsiveness of auditory and visual cortex in 5 cats and of vertex and occipital derivations in 12 human subjects. The evoked potentials were studied in the frequency domain by means of the Fourier transform. Furthermore, digital filtering was applied to confirm and extend the analysis. Preliminary results indicate that resonances were observed mainly in the 5, 10, 20 and 40 Hz frequency bands. The frequency of resonance maxima depended on the sites of measurement electrodes and stimulus modality. It is concluded that the analysis of resonance phenomena in the brain is a useful approach to understanding the relation between evoked potentials, evoked magnetic fields and single-cell recordings.

The associations between 40 Hz-EEG and the middle latency response of the auditory evoked potential.

The study of the 40 Hz activity of the brain which was begun by Adrian (1942) has been furthered for the past years with several new approaches: A neural model for the generation of 40 Hz activity in attention has been published by Freeman (1975) whereas new possibilities in clinical applications and exploration of cognitive processes in an extended manner was proposed by Galambos and coworkers (1981). The present study demonstrates the relation between 40 Hz spontaneous activity in human EEG-recordings and the middle latency response of the auditory evoked potentials. The applied signal analysis method allows also a single trial analysis of EEG-EP epochs which can be extended in studies on cognitive processes. A perspective concerning the middle latency response of the auditory AEP is also given.