Search

Contains fulltext : 239574.pdf (Publisher’s version ) (Closed access) Open science initiatives are creating opportunities to increase research coordination and impact in nonhuman primate (NHP) imaging. The PRIMatE Data and Resource Exchange community recently developed a collaboration-based strategic plan to advance NHP imaging as an integrative approach for multiscale neuroscience. 5 p.

The use of single antagonistic yeasts and bacteria to control postharvest diseases expanded globally during the 1990s into the 2000s with multiple antagonists being commercialized as postharvest biocontrol agents. The advent of deoxyribonucleic acid (DNA) sequencing and molecular identification of microorganisms completely changed our perspective on potential postharvest biological control antagonists and their microecology. Breeding fewer bitter plants involved the development of plants with a reduced content of bitter compounds such as alkaloids and phenolics that are resistant compounds against postharvest plant pathogens. It was suspected early on that there were “natural” postharvest biocontrol systems that exist on the surfaces of fruits and vegetables. Synthetic fungicides are predominantly used to control postharvest diseases of fruits and vegetables. Even after over 35 years of research on the biological control of postharvest diseases, a very small number of products are used as alternatives to synthetic fungicides.

The world's food supply is shrinking and we are heading toward a world food shortage crisis. On one side we have a rapidly exploding world population and on the other side we have a rapidly deteriorating agricultural environment. Global warming has come on the scene and portends to greatly reduce crop yields. It has been shown that we cannot meet this global food shortage crises by just producing more food as we did during the “Green Revolution”. Since one-third of the food that we already produce is lost between the time that it is harvested and consumed it makes sense that we need to substantially reduce these postharvest losses if we are to feed the world's increasing population. Due to a meager investment of our agricultural resources into food preservation (5%) versus food production (95%) a postharvest “Skill Gap” and “Technology Gap” exists in our higher education systems particularly in developing countries. The World Food Preservation Center® LLC is filling these gaps by providing a world-class postharvest education to young student/scientists from developing countries and having them conduct research on much needed new postharvest technologies.

The application of ultraviolet light (UV-C, 254 nm) hormesis on fruits and vegetables to stimulate beneficial responses is a new method for controlling storage rots and extending the shelf-life of fruits and vegetables. The present study was aimed at treating tomatoes ( Lycopersicon esculentum ) with different UV-C dosages (1.3 to 40 KJ/m2) to induce resistance to black mold ( Alternaria alternata ), gray mold ( Botrytis cinerea ), and Rhizopus soft rot ( Rhizopus stolonifer ). These diseases were effectively reduced when tomatoes were inoculated following UV-C irradiation. UV-C treated tomatoes were firmer in texture and less red in color than the control tomatoes, indicating a delay in ripening. Slower ripening and resistance to storage rots of tomatoes are probably related. The positive effect of UV-C on tomatoes decreased as treatments were performed at stages of increased ripeness.

A rapid assay to determine antifungal activity in plant extracts and essential oils is described. Wells in microtiter plates were loaded with Botrytis cinerea spores and plant extracts or essential oils. Subsequent changes in optical density following spore germination in the wells was measured after 24 h using an automatic microtiter plate reader driven by a software program developed for this purpose. Extracts from 345 plants and 49 essential oils were evaluated for their antifungal activity against B. cinerea. Among 345 plant extracts analyzed, 13 showed high levels of antifungal activity, with species of Allium and Capsicum predominating. Among the 49 essential oils tested, palmarosa (Cymbopogon martini), red thyme (Thymus zygis), cinnamon leaf (Cinnamomum zeylanicum), and clove buds (Eugenia caryophyllata) demonstrated the most antifungal activity against B. cinerea. The most frequently occurring constituents in essential oils showing high antifungal activity were: D-limonene, cineole; β-myrcene; α-pinene, β-pinene; and camphor.

A combination of Candida saitoana with 0.2% 2-deoxy-D-glucose to control decay of apple, lemon, and orange fruit was evaluated. Growth of C. saitoana in vitro was reduced by 2-deoxy-D-glucose; however, in apple wounds, the yeast grew as well in the presence of 2-deoxy-D-glucose as in its absence. When applied to fruit wounds before inoculation, the combination of C. saitoana with 0.2% 2-deoxy-D-glucose was more effective in controlling decay of apple, orange, and lemon caused by Botrytis cinerea, Penicillium expansum, and P. digitatum than either C. saitoana or the application of a 0.2% solution of 2-deoxy-D-glucose alone. Increasing the concentration of 2-deoxy-D-glucose from 0.2 to 0.5% did not improve control significantly. The combination of C. saitoana with 0.2% 2-deoxy-D-glucose was also effective against infections established up to 24 h before treatment. When applied within 24 h after inoculation, the combination of C. saitoana with 0.2% 2-deoxy-D-glucose was very effective in controlling blue mold of apple and green mold of orange and lemon. The level of control of green mold was equivalent to imazalil treatment. When either C. saitoana or 0.2% 2-deoxy-D-glucose was applied within 24 h after inoculation, neither had an effect on disease development on apple, orange, or lemon, and the incidence of decay was similar to the water-treated control.

How did humans sleep before the modern era? Because the tools to measure sleep under natural conditions were developed long after the invention of the electric devices suspected of delaying and reducing sleep, we investigated sleep in three preindustrial societies [1-3]. We find that all three show similar sleep organization, suggesting that they express core human sleep patterns, most likely characteristic of pre-modern era Homo sapiens. Sleep periods, the times from onset to offset, averaged 6.9-8.5 hr, with sleep durations of 5.7-7.1 hr, amounts near the low end of those industrial societies [4-7]. There was a difference of nearly 1 hr between summer and winter sleep. Daily variation in sleep duration was strongly linked to time of onset, rather than offset. None of these groups began sleep near sunset, onset occurring, on average, 3.3 hr after sunset. Awakening was usually before sunrise. The sleep period consistently occurred during the nighttime period of falling environmental temperature, was not interrupted by extended periods of waking, and terminated, with vasoconstriction, near the nadir of daily ambient temperature. The daily cycle of temperature change, largely eliminated from modern sleep environments, may be a potent natural regulator of sleep. Light exposure was maximal in the morning and greatly decreased at noon, indicating that all three groups seek shade at midday and that light activation of the suprachiasmatic nucleus is maximal in the morning. Napping occurred on 7% of days in winter and22% of days in summer. Mimicking aspects of the natural environment might be effective in treating certain modern sleep disorders.

Intracranial depth electrode recordings indicate that the majority of seizures in patients with temporal lobe epilepsy (TLE) may be segregated into two groups based on electrographic ictal onset patterns (Engel, 1990). Hypersynchronous (HYP) onsets consist of long-lasting (>5-s) trains of low-frequency (

The use of biocontrol agents as an alternative to synthetic, chemical fungicides that are presently used to control postharvest pathogens, has many constraints and obstacles that make it difficult to implement their use as a practical control strategy. Over the last 20 years postharvest biocontrol research has evolved towards being more integrated into a production systems approach with greater awareness of industry concerns. More research, however, is needed in many aspects of the science and technology of postharvest biocontrol and in integrating biocontrol agents into combined pre- and postharvest production and handling systems. Better understanding of the mode of action of postharvest biocontrol agents, relationships between infection levels occurring in the field and development of postharvest decay, along with basic information on microbial ecology and survival mechanisms of biocontrol agents on fruit surfaces, is critical for the advancement of successful implementation of postharvest biocontrol technology. The past 20 years of postharvest biocontrol research has seen tremendous advances and the creation of several products. Nonetheless, numerous challenges and opportunities still exist as this field of research matures. This review is an attempt to examine the field of postharvest biocontrol as it has developed over the past 20 years, define the reasons that have limited its commercialization, and identify areas of research that need to be addressed if the potential of postharvest biocontrol is to be achieved. We have also introduced a new paradigm for biocontrol research that may provide new opportunities for increasing the efficacy and consistency of biocontrol products.

Summary Purpose: To determine whether hippocampal sclerosis might form an anatomical substrate for pathological high-frequency oscillations in patients with temporal lobe epilepsy (TLE). Methods: Intracerebral wide bandwidth electroencephalogram was recorded in patients with medically intractable complex partial seizures. A computer-automated program detected interictal normal ripples (80–150 Hz) and pathologic fast ripples (FR, 151–500 Hz) from microelectrodes within hippocampus, entorhinal, and subicular cortices. Hippocampal MRI volumetric analysis and cell density measurements were correlated with rates of FR and ripple discharge. Results: In all 13 patients, higher rates of FR (p = 0.03) and ratios of FR to ripple discharges (p = 0.02) were observed in sites ipsilateral to seizure onset compared with rates within contralateral nonictal sites. Higher ratios of FR to ripple discharge were associated with smaller ipsilateral hippocampal volumes (p = 0.02) and lower fascia dentata (FD; p = 0.02) and Ammon's horn (p = 0.0005) neuron densities. While reduced FD and Ammon's horn neuron densities correlated with higher ratios of discharges, stepwise multiple regression analysis revealed that decreased neuron densities within CA1 and prosubiculum regions most strongly predicted ratios of FR to ripples (r2= 0.78, p = 0.008). Conclusions: In surgical patients with TLE, higher ratios of FR to ripple discharges are associated with histopathologic changes found in hippocampal sclerosis. These findings support the hypothesis that pathological alterations linked with hippocampal cell loss and synaptic reorganization promote FR and reduce ripple generation.

High-frequency oscillations (HFOs) have been described in normal and epileptic brains of animals and humans. These oscillations reflect a short-term integration within neuronal networks and have important functional consequences for normal and pathological processes. We performed a comparative voltage depth profile analysis of normal and pathological HFOs after intrahippocampal kainic acid injection. Sixteen channel recording probes, with 100-200 microm separation between the tips of microelectrodes, were implanted along the CA1-dentate gyrus axis in the anterior hippocampus of adult rats. Guide cannulae were implanted in the CA3 area. After a week of baseline recording kainic acid (KA) (0.2microg/0.2microl) was injected into the CA3 area. Electrical activity continued to be record for the next 3-4 weeks after KA induced status epilepticus. Voltage depth profiles and power spectral analysis of HFOs were performed off-line using DataPac software. Ripple oscillations (80-200 Hz) in the CA1 area and gamma activity (40-80 Hz) in the dentate gyrus remained after status epilepticus. In the group of rats that later developed seizures a new pattern consisting of bursts of population spikes (BPS) occurred. The maximum of amplitude for BPS generated in CA1 was in the pyramidal layer and for those generated in the dentate gyrus was in the granular layer. BPS appeared 2-3 days after status epilepticus and remained for the rest of the experiments. The frequencies of intraburst spikes varied between 80 Hz and 600 Hz. With increasing distance from the area of the burst generation, this activity took on the appearance of HFOs. The occurrence of spontaneous BPS appear to be a primary electrophysiological consequence of status epilepticus when progressive epileptogenesis occurs with maximum of amplitude in the cellular layer. In areas outside of the generator of the BPS, this activity looks more like pathological high-frequency oscillations (pHFO), which were observed in earlier experiments.

Chitosan, a given name to a deacetylated form of chitin, is a natural biodegradable compound derived from crustaceous shells such as crabs and shrimps, whose main attributes corresponds to its polycationic nature. Chitosan has been proven to control numerous pre and postharvest diseases on various horticultural commodities. It has been reported that both soil and foliar plant pathogens fungal, bacterial and viral may be controlled by chitosan application. Microscopical observations indicate that chitosan has a direct effect on the morphology of the chitosan-treated microorganism reflecting its fungistatic or fungicidal potential. In addition to its direct microbial activity, other studies strongly suggest that chitosan induces a series of defence reactions correlated with enzymatic activities. Chitosan has been shown to increase the production of glucanohydrolases, phenolic compounds and synthesis of specific phytoalexins with antifungal activity, and also reduces macerating enzymes such as polygalacturonases, pectin metil esterase etc. In addition, chitosan induces structural barriers for example inducing the synthesis of lignin-like material. For some horticultural and ornamental commodities, chitosan increased harvested yield. Due to its ability to form a semipermeable coating, chitosan extends the shelf life of treated fruit and vegetables by minimizing the rate of respiration and reducing water loss. As a nontoxic biodegradable material, as well as an elicitor, chitosan has the potential to become a new class of plant protectant, assisting towards the goal of sustainable agriculture.

The goal of this study was to characterize the electrophys- iological features of single neurons recorded deep within the medial tem- poral lobes in humans. Using three physiological criteria to distinguish principal cells and interneurons (firing rate, burst propensity, and action potential waveform) and a large data set of human single neurons (585) from thirteen patients, we show that single neurons in the human MTL separate into two distinct classes comparable to the pyramidal cell and interneuron classes described in animals. We also find that the four dif- ferent MTL brain regions that we examined (amygdala, hippocampus, entorhinal cortex, and posterior parahippocampal cortex) show unique action potential characteristics, which may in turn relate to the role that neurons from these regions play in behavior. A subset of cells were recorded while patients engaged in both slow-wave (SWS) and rapid-eye movement (REM) sleep and a comparison of the electrophysiological fea- tures during these different sleep stages showed that interneurons tended to burst more during SWS compared to REM, while only principal cells in the EC and hippocampus showed a greater propensity for bursting during SWS. Together, our results support the idea that human single neurons have electrophysiologically identifiable cell types, similar to those observed in other mammals, and provide insight into regional and func- tional differences in spike-wave characteristics relevant to considerations about neural populations in the human brain. V C 2006 Wiley-Liss, Inc.

Objective The effects of transcranial magnetic stimulation (TMS) on vagus nerve stimulation (VNS) are unknown. Understanding these effects is important before exposing individuals with an implanted VNS to TMS, as could occur in epilepsy or depression TMS research. To explore this issue, the TMS-induced current in VNS leads and whether TMS has an effect on the VNS pulse generator was assessed. Methods Ex vivo measurement of current in VNS leads during single-pulse TMS and pulse generator function before, during, and after single-pulse TMS was assessed. Results At the highest intensity and with the TMS coil held ∼5 mm from the VNS wires, a 200 nA, 1.0 ms current was induced by TMS. This translates to an induced charge density of 3.3 nC/cm 2 /phase. The function of the pulse generator was unaffected by single-pulse TMS, even when its case was directly stimulated by the coil. Conclusions TMS-induced current in VNS electrodes was not only well outside of the range known to be injurious to peripheral nerve, but also below the activation threshold of nerve fibers. Significance Using single-pulse TMS in individuals with VNS should not result in nerve stimulation or damage. Furthermore, single-pulse TMS does not affect the VNS pulse generator's function.

Summary: Purpose: The goal of this study was to analyze the transition period between interictal and ictal activity in freely moving rats with recurrent spontaneous seizures after unilateral intrahippocampal kainic acid (KA) injection. Methods: Pairs of tungsten electrodes (50 μm O/D) were implanted bilaterally under anesthesia at symmetrical points in the dentate gyrus (DG) and CA1 regions of anterior and posterior hippocampi and entorhinal cortex of adult Wistar rats. Stimulating electrodes were placed in the right angular bundle and KA was injected into the right posterior CA3 area of hippocampus after 1 week of baseline EEG recording. Beginning 24 h after injection, electrographic activity was recorded with video monitoring for seizures every day for 8 h/day for 60 days. Results: Seventy percent of seizures started locally in the DG ipsilateral to injection, with an increase in frequency of interictal EEG spikes (hypersynchronous type, HYP), and 26% of seizures started with a decrease of EEG amplitude with parallel increase in frequency (low-voltage fast type, LVF). During HYP seizures, a significant increase was observed in amplitude of beta-gamma range frequencies, ripple frequency, and fast ripple (FR) frequency, whereas during LVF seizure, an increase was noted only in the beta-gamma range. In all cases but one, an EEG wave preceded ripple and FR oscillations. Before seizure onset, the amplitude of DG-evoked responses to single pulses decreased, whereas the amplitude of the response to the second pulse delivered at 30-ms interval increased. Conclusions: If ripple and FR oscillations indicate the seizure-generating neuronal substrate, these areas must be small and widespread, so that the probability of recording from them directly is very low. The decreased response to electrical stimulation before seizures could indicate a protective inhibitory mechanism that contains or prevents seizure occurrence. The presence of decreased paired-pulse suppression could indicate a network predisposition to follow an external input with a certain frequency.

The possibility of inducing resistance to bitter rot ( Colletotrichum gloeosporioides ), brown rot ( Monilinia fructicola ), and green mold ( Penicillium digitatum ) in apples, peaches, and tangerines, respectively, by treating them with ultraviolet light-C (UV-C light) at the stem end in a stationary position without rotation was investigated. This approach was compared with the conventional procedure where fruits were rotated four times, thereby exposing the entire surface area to the full effects of the UV-C light. Results revealed that when the stem ends of apples, peaches, and tangerines were exposed in a stationary position to dosages of 7.5, 7.5 and 1.3 kJ m −2 of UV-C light, respectively, induced host resistance to postharvest decay which was equal to, or slightly better than when fruits were rotated four different times. When fruits were rotated, exposing only one or two different sides to UV-C light, the percent infection appeared to increase, compared to treating only the stem ends or when fruits were rotated four times.

A receptor-like protein kinase gene (Ppsrkl1) was isolated from a peach (Prunus persica (L.) Batsch.) bark cDNA library prepared with RNAs isolated from bark collected in December (cold acclimated). Sequence analysis indicated that this gene is related to the S-locus family of receptor protein kinases (SRKs) and that it shares greatest homology with ZMPK1 from maize and At4g32300 from Arabidopsis, both of which are intron-less genes. In bark tissues, Ppsrkl1 is induced by water deficit treatment, repressed by short-day photoperiods and showed no response to cold treatment. The Ppsrkl1 mRNA also increased in roots in response to water deficit. In fruit, Ppsrkl1 shows no response up to 6 h after wounding, but at 12 and 24 h after wounding, Ppsrkl1 mRNA shows an abrupt decline. This decline was prevented by the addition of salicylic acid to the wound site. The Ppsrkl1 mRNA rapidly decreased in fruit after 10-min exposure to UV-C radiation, followed by a return to normal levels within 1.5 h. Taken together, these experiments indicate that Ppsrkl1 is negatively regulated by light and positively influenced by salicylic acid treatment in fruit and water stress in bark and roots.

Summary: Purpose: To investigate the temporal relation between high-frequency oscillations (HFOs) in the dentate gyrus and recurrent spontaneous seizures after intrahippocampal kainite-induced status epilepticus. Methods: Recording microelectrodes were implanted bilaterally in different regions of hippocampus and entorhinal cortex. A guide cannula for microinjection of kainic acid (KA) was implanted above the right posterior CA3 area of hippocampus. After recording baseline electrical activity, KA (0.4 µg/0.2 µl) was injected. Beginning on the next day, electrographic activity was recorded with video monitoring for seizures every day for 8 h/day for ≥30 days. Results: Of the 26 rats studied, 19 revealed the appearance of sharp-wave activity and HFOs in the frequency range of 80 to 500 Hz in the dentate gyrus ipsilateral to the KA injection. In the remaining seven rats, no appreciable activity was noted in this frequency range. In some rats with recurrent seizures, HFOs were in the ripple frequency range (100‐200 Hz); in others, HFOs were in the fast ripple frequency range (200‐500 Hz), or a mixture of both oscillation frequencies was found. The time of detection of the first HFOs after status epilepticus varied between 1 and 30 days, with a mean of 6.3 ± 2.0 (SEM). Of the 19 rats in which HFO activity appeared, all later developed recurrent spontaneous seizures, whereas none of the rats without HFOs developed seizures. The sooner HFO activity was detected after status epilepticus, the sooner the first spontaneous seizure occurred. A significant inverse relation was found between the time to the first HFO detection and the subsequent rate of spontaneous seizures. Conclusions: A strong correlation was found between a decreased time to detection of HFOs and an increased rate of spontaneous seizures, as well as with a decrease in the duration of the latent period between KA injection and the detection of spontaneous seizures. Two types of HFOs were found after KA injection, one in the frequency range of 100 to 200 Hz, and the other, in the frequency range of 200 to 500 Hz, and both should be considered pathological, suggesting that both are epileptogenic. Key Words: Epileptogenesis— High-frequency oscillations—Dentate gyrus—Kainic acid— Rat.

Low-dose application of hormetic (adj. of hormetin, the agent of hormesis e.g. UV-C) ultraviolet light-C (UV-C) to ‘Better Boy’ and ‘Floradade’ tomatoes at maturity resulted in fruits that were significantly, firmer than non-irradiated control fruits at the same stage of maturity. As, firmness increased following UV-C treatment, polygalacturonase (PG) activity decreased. The enzyme activity was lower for UV-C treated fruits than the control. The PG activity in crude extract from decayed tomato tissue infected with Rhizopons stolonifer was lower than non-decayed fruits. UV-C treated tomatoes showed a 40% reduction in PG activity in decayed tissue compared to the control at 72 h after treatment. The lesion diameter, and percent infection of non-treated and UV-C treated tomatoes at 72 h after treatment, was 13.4 mm (100% infection), and 5.3 mm (47% infection), respectively.

The normal processes of learning and memory as well as the pathological progress of various neurological diseases may result in changes in gene expression in small, local populations of neurons in any given brain area, leading to the occurrence of specific patterns of electrical activity without easily detectable changes in the morphology of this brain area. One way of identifying these changes might be the comparison of gene expression of areas which generate and areas which do not generate specific patterns of electrical activity. A method for microbiopsy of limited (0.5-1.0 mm3) tissue samples from electrophysiologically identified areas of neurons generating epileptiform activity in the rat brain is described. Here we demonstrate that total RNA isolated from individual microbiopsy samples might be successfully used for microarray based gene expression analysis of any discretely localized neuronal group which can be identified electrophysiologically, including neurons in cortical columns, cell assemblies or other functional units.

Summary: Many different types of epileptic seizures and epileptic syndromes exist. The process of epileptogenesis and the progressive nature of epilepsy, however, can most easily be investigated in the acquired epilepsies, in which a brain insult presumably gives rise to changes in neuronal systems that ultimately become capable of generating spontaneous ictal events. Invasive in vivo and in vitro research can be carried out in patients with acquired epileptogenic lesions in the course of epilepsy surgery; however, such studies are possible only for those epileptic conditions that can be treated surgically, and can be used only to examine an end stage of the epileptogenic process. Consequently, experimental animal models of human epileptic conditions are still required to study mechanisms by which specific cerebral insults initiate the epileptogenic process and the progression of an epileptic disturbance. Most current parallel human/animal invasive research has been focused on temporal lobe epilepsy, and particularly that form associated with hippocampal sclerosis, the most common human epileptogenic lesion. Studies indicate that epileptogenesis in this condition is initiated by specific types of cell loss and neuronal reorganization, which results not only in enhanced excitation, but also in enhanced inhibition, predisposing to hypersynchronization. Even within this single, well-studied epileptic disorder, evidence is found for more than one type of ictal onset, and individual seizures can demonstrate a transition from one ictal mechanism to another. Recent in vivo and in vitro parallel, reiterative investigations in patients with mesial temporal lobe epilepsy, and in rats with intrahippocampal kainate-induced hippocampal seizures, have revealed the presence of interictal epileptiform events, termed “fast ripples,” which appear to be unique in tissue capable of generating spontaneous seizures. Pursuit of the fundamental mechanisms underlying these abnormalities should elucidate the neurobiologic basis of epileptogenicity in this disorder. Furthermore, if these events are markers for epileptogenicity, they may have clinical value for diagnosis and pharmacologic, as well as surgical, treatment. Further research is needed to determine if these observations are relevant to other types of epilepsies.

The objectives of this research were to evaluate the in vitro fungicidal effect of chitosan and aqueous extracts of custard apple leaves, papaya leaves and papaya seeds, and the combination of chitosan and plant extracts on the development of Colletotrichum gloeosporioides, which causes anthracnose on papaya. Chitosan at 2.0% and 3.0% had a fungicidal effect on C. gloeosporioides. Extracts alone did not show any fungicidal effect while the combination of 2.5% chitosan with all the tested extracts had a fungistatic rather than fungicidal effect. Changes in the conidial morphology of C. gloeosporioides were observed with 1.5% chitosan concentration after 7 h incubation. For in situ studies, control of anthracnose disease was obtained with 1.5% chitosan applied before C. gloeosporioides inoculation. Phomopsis was most frequently isolated from the non-inoculated fruit. Chitosan applications did not influence the content of total solid solubles or percentage weight loss during the storage of papaya fruit. However, there was a tendency toward greater firmness in fruit treated with the papaya seed extract alone or combined with chitosan.

Summary: Purpose: Fast ripples (FRs) are interictal, pathological, high-frequency oscillations in the 200- to 600-Hz range, which can be recorded from limbic regions capable of generating spontaneous seizures in rodent models of epilepsy and in human mesial temporal lobe epilepsy. To evaluate the spatial stability of FR-generating brain areas over long periods, we monitored interictal FR oscillations in rats with chronic recurrent spontaneous seizures. Methods: After unilateral intrahippocampal injection of kainic acid, 22 rats were video monitored until spontaneous behavioral seizures occurred, and then implanted with multiple hippocampal, dentate gyrus, and entorhinal cortex microelectrodes. Electrophysiological monitoring of microelectrode sites was carried out during daily 8-h recordings for periods ranging from 6 to 98 days. Results: Interictal FRs were recorded from discretely localized areas, adjacent to non–FR-generating areas in dentate gyrus and entorhinal cortex. The location of interictal FR oscillations remained fixed, and the electrophysiological pattern of FRs remained the same over the time of our study. For the duration of monitoring, sites initially recording interictal FRs continued to display FR oscillations, and sites that initially did not record FRs never demonstrated FR activity. A direct relation was seen between the total number of electrode contacts recording interictal FRs and the frequency of spontaneous seizure generation (p < 0.0001). Conclusions: These results suggest that interictal FRs reflect abnormal discharges from a fixed pathologic substrate imbedded within less-epileptogenic tissue, and that spontaneous seizure frequency is dependent on the extent and distribution of this pathologic substrate.

The fungistatic or fungicidal effect of powders, and aqueous and ethanolic extracts of seeds, and monthly harvested leaves of huamuchil (Pithecellobium dulce ) were evaluated for fungicidal activity, against Botrytis cinerea , Penicillium digitatum , and Rhizopus stolonifer . Fungicidal activity of huamuchil powders and aqueous extracts were also evaluated on strawberry fruit during storage. Preliminary characterization of the active compound responsible for the fungicidal effect was carried out using thin layer chromatography and spectrophotometry. Results indicated that powders had the best fungicidal effect, in both in vitro and in situ studies. Fungistatic or fungicidal properties were associated with the plant organ and harvest month. A correlation between high absorbance values of extracts with the fungicidal or fungistatic effect was not observed. The highest fungistatic or fungicidal effect for both in vitro and in situ studies was recorded from extracts of leaves harvested in months having more stressful environmental conditions; the cold season (October/February) and, the dry, hot season (April and June). Attempts to characterize the active compound suggest that kaempferol may be responsible for the fungicidal effect. # 2003 Elsevier Science B.V. All rights reserved.