Search PubMed⌕ Search

Biomedical subjects

B Peretz

Publications and source records attributed to B Peretz.

At least 91 records · Page 5Linked to original sources
PubMed1981

Age-dependent behavioral changes and physiological changes in identified neurons in Aplysia californica.

The gill withdrawal reflex (GWR) to direct gill stimulation was studied in sexually mature Aplysia and in those older by at least two months. The GWR threshold in old Aplysia was five- to sevenfold higher than that in mature animals. In the habituation paradigm, the GWR amplitude decremented rapidly to zero in old animals whereas in mature animals it persisted for at least ten trials. The GWR could not be dishabituated in old animals. The GWR is an age-dependent behavior in that parieto-visceral ganglion suppression of the GWR appears to increase with age. Also the electrophysiological properties of two neurons in the parieto-visceral ganglion were compared in the two age groups: L7 a neuron which dishabituates the GWR in mature and not in old animals; and R2 which manifests cytological changes with age. In old animals L7's input resistance was lower, the time constant was increased, and the size of the psp evoked by gill stimulation was smaller than those of mature L7s. Similar membrane changes with age were measured in R2. Soma size of L7 was approximately the same in the two age groups as was that of R2. The physiological parameters of neurons of known function continue to change during postmetamorphic life of Aplysia.

Aging↗
PubMed1980

Quantal transmitter release in an identified inhibitory cholinergic synapse of Aplysia.

A sustained postsynaptic potential is observed in an identified synapse of Aplysia when the presynaptic neuron is depolarized in the presence of tetrodotoxin (TTX). This prolonged postsynaptic potential appears to be at least in part due to the summation of quantal events. It is still observed when 30 mM CoCl2, which is known to inhibit Ca2+ influx, is added to the external media.

Acetylcholine↗
PubMed1980

Control of gill reflex habituation and the rate of EPSP decrement of L7 by a common source in the CNS of Aplysia.

It was found in older Aplysia that the rate of decrement of the EPSP evoked in L7 by repreated tactile stimulation of the gill was dependent on the strength of the applied stimulus and that the rate of decrement paralleled the rate of gill reflex habituation. As the stimulus intensity was increased both rates slowed. In contrast, it was found in young Aplysia that the rate of EPSP decrement and the rate of gill reflex habituation were independent of the strength of the stimulus applied to the gill. Neither rate changes as the stimulus intensity was changed. Moreover, L7's of young animals are more responsive to tactile stimuli applied to the gill than are L7's of older animals, and the difference in excitability is not due to any differences in passive membrane properties between the L7's in young and older Aplysia. These findings are fully consistent with and supportive of the proposal that a common neuronal source in the parieto-visceral ganglion of Aplysia controls the rate of gill reflex habituation, the synaptic input to L7, and the rate of decrement of this input, evoked by repeated tactile stimulation of the gill. Additionally, it was proposed that this common source is developed incompletely in the young. As a consequence of this incomplete development, young Aplysia exhibit less adaptability to changing stimulus conditions and, in general, less ability to suppress their behavior. It may thus be possible to study directly developmental changes in the nervous system which act to transform juvenile behavior to adult behavior.

Aging↗
PubMed1976

Habituation of reflexes in Aplysia: contribution of the peripheral and central nervous systems.

We studied the contribution of the Aplysia peripheral nervous system, in the siphon and gill, to habituation of the gill withdrawal reflex. After removal of one central ganglion, the parietovisceral, repeated stimulation of the siphon caused habituation of the reflex as it had with the ganglion intact, showing that there is a peripheral pathway between the siphon and gill with competence to mediate habituation. Repeated electrical stimulation of two efferent nerves to the gill, after removal of the parietovisceral ganglion, resulted in habituation of withdrawal movements, which shows that the terminals of the ganglion neurons in the gill are a site of habituation. Also, stimulation of one nerve dishabituates the withdrawal movements elicited by the other. These identify two sites of habituation in the gill in addition to sites in the parietovisceral ganglion.

Animals↗
PubMed1970

Habituation and dishabituation in the absence of a central nervous system.

Habituation and dishabituation have been observed in a semi-intact Aplysia preparation in which the central nervous system is removed. The amplitude of withdrawal responses in the gill decreases in proportion to the rate of water drops applied (one drop per 0.5 minute to one drop per 2.5 minutes at 15 degrees C). The effects of habituation last for at least 2 hours. A dishabituated response is elicited by stopping the water drops or electrically stimulating the preparation. Furthermore, the gill contains nerve cell bodies, and habituation and dishabituation appear to be properties of these peripheral neurons.

Animals↗
PubMedDate not supplied

Crown size asymmetry in males with fra (X) or Martin-Bell syndrome.

We measured the mesio-distal and bucco-lingual crown diameters of 13 males with the fra(X) or Martin-Bell syndrome. Fluctuating crown-size asymmetry was calculated and compared with values obtained in normal Caucasian children and also with a sample of 19 males with Down syndrome. A statistically significant increased asymmetry was found in the fra(X) males when compared to normal control individuals. In the maxilla, Down syndrome males showed a significantly higher tooth crown asymmetry than fra(X) males. (less than 0.02); in the mandible, no significant differences were found between the 2 groups. It is suggested that crown size asymmetry be included in the evaluation of fra(X) males.

Down Syndrome↗
PubMedDate not supplied

Increased age affects properties characterizing behavioral plasticity in freely behaving Aplysia.

In the marine mollusc Aplysia, in vitro studies showed that the gill withdrawal reflex (GWR) and its neuronal substrates were altered by age. In contrast, age minimally affected the gill respiratory pumping movements (GPM) and its neuronal substrates. Based on the respective properties of the GWR- and GPM-pathways in vitro, we proposed that the more pronounced the effect of age, the greater the expression of plasticity in a pathway. This conclusion may hold for in vitro preparations, but it remained to be demonstrated in intact animals. Based on this conclusion, the GWR should exhibit greater plasticity than the GPM in intact animals. Using freely behaving Aplysia, we tested for plasticity of the GWR and the GPM in three age groups (young, mature, and old). The tests for behavioral plasticity were: Graded responses to varying stimulus strength, response decrement (or habituation) to repetitive stimulation, enhanced response to dishabituating stimuli, and the effect of the GWR stimulus on the GPM and the GPM stimulus on the GWR. The GWR in mature animals exhibited all four properties, but in old animals, graded responses and habituation were significantly altered and in young animals habituation and dishabituation were absent. The GPM exhibited fewer of the properties than the GWR, only graded responses and response decrement, both of which were generally the same in the three groups. We found that behavioral plasticity and age-induced plasticity are related in freely behaving animals and are consistent with in vitro findings. The effect of age on properties characterizing plasticity at both the behavioral and pathway levels is discussed.

Aging↗
PubMedDate not supplied

Excitability and branching of neuroendocrine cells during reproductive senescence.

In the mollusc Lymnaea stagnalis, neuroendocrine caudodorsal cells (CDCs) were studied physiologically and morphologically from egg layers (EL) (aged 154-400), and animals 4 weeks (CEL-4) (342-455 days), and 8 weeks (CEL-8) (477-660 days) after production of their last egg mass. After recording chemical transmission, electrical coupling and stimulation induced afterdischarges (ADs), CDCs then were filled with Lucifer Yellow. Based on the axonal branching revealed by Lucifer Yellow, CDCs were classified as extensively, moderately, or minimally branched. In EL-CDCs, induction of AD activity, which normally (9) precedes egg-laying, only was initiated in the resting state. CEL-4 CDCs exhibited ADs whereas CEL-8 CDCs did not. CEL-8 CDCs exhibited significantly reduced chemical and electrical transmission, and CEL-4 CDCs did not differ from resting state EL-CDCs. CDC branching was significantly reduced with both increasing age and declining egg-laying. Minimally branched CDCs most frequently failed to exhibit an AD and exhibited reduced electrical coupling. We conclude that both physiology and morphology of CDCs are related to age and reproductive state.

Aging↗
PubMedDate not supplied

Non-institutionalized elderly dental patients in Israel: socio-demographics, health concerns, and dental anxiety.

The purpose of this study was to evaluate which factors might influence health care attitudes such as anxiety about dental care by older adults in Israel. The study population consisted of 103 non-institutionalized patients (46 men and 57 women) over the age of 65 who attended a dental clinic that provided services for older adults during a one-year period. Socio-demographic information and information about the subjects' general health and their level of concern about health problems were obtained from self-reported questionnaires, while the dental anxiety level was found by means of a dental anxiety scale (DAS). Ninety-nine percent of the patients suffered from a major systemic disease such as diabetes, hypertension, atherosclerosis, respiratory disease, and rheumatic disease. Both unmarried and first-time patients expressed high anxiety scores. Patients with 12 or fewer years of formal schooling demonstrated significantly higher dental anxiety. Among patients who regularly attended a synagogue or a social club, concern about oral health was significantly higher than for the rest (p < 0.02). No association was found between having dentures and gender, or between having dentures and level of education. The reason for visiting the clinic (inability to eat, pain, or esthetics) was not associated with any other health concern or with dental anxiety levels. This study determined that patients who were unmarried, less educated, or attending the facility for the first time were more likely to experience dental anxiety. These patients merit special consideration.

Aged↗
PubMedDate not supplied

Parents' attitudes toward behavior management techniques during dental treatment.

PURPOSE: This study investigated the attitudes of parents toward behavior management techniques used during dental treatment of children. METHODS: One hundred and four parents who accompanied their children to the Department of Pediatric Dentistry at the Hebrew University, Hadassah Faculty of Dental Medicine in Jerusalem, Israel, participated in the study. The techniques for managing the children's behavior were explained to the parents prior to treatment and parents were present in the operatory during dental treatment. At the end of the second appointment, parents completed a questionnaire requesting demographic, behavioral, and dental information as well as the parents' attitudes toward the management techniques. RESULTS: Most parents preferred an explanation as to the proper approach for treating their children. Voice control was totally accepted by most parents, Papoose Board by one-third of the parents and physical restraint by nearly one-fourth of the parents. Of the parents who were in favor of restraint, most children did not cooperate. CONCLUSION: Detailed explanations and witnessing children during dental treatment may raise parents' tolerance level to firm techniques.

Adolescent↗
PubMedDate not supplied

Herpes simplex-associated erythema multiforme (HAEM): a clinical therapeutic dilemma.

Erythema multiforme of the mouth is an acute vesiculo-ulcerative lesion, which presents a diagnostic and therapeutic challenge to the clinician. Herpes simplex is described as the most frequent cause of this disease. Controversy exists in the literature as to the definition of oral erythema multiforme and the role of systemic corticosteroids in its treatment. Recent treatment protocols advocate the use of systemic acyclovir, especially in cases triggered by the herpes simplex virus. Two cases of successful treatment of oral erythema multiforme with systemic corticosteroids after acyclovir treatment had failed are presented.

Acute Disease↗
PubMedDate not supplied

Behavior and toothbrushing of young Israeli adolescents.

The purpose of the present study was to assess the toothbrushing behavior of Israeli adolescents attending a pediatric dental clinic, with regard to the maxillary anterior region. One hundred twenty-three adolescents (57 boys, 66 girls, mean age 12.45 +/- 1.76), participated in this study. The amount of plaque extending from the gingival line incisally was measured. Brushing characteristics and daily habits were recorded. In 87 patients, 4 mm or more of plaque were measured on the labial surfaces of the maxillary central incisors, while thirty-six patients demonstrated less than 4 mm plaque. Patients who brushed the maxillary and mandibular incisors separately showed significantly less plaque than patients who brushed them simultaneously. Brushing the maxillary and the mandibular incisors separately was significantly more prevalent in the thirteen-to-seventeen-year-olds, and among girls. Also, significantly more girls brushed twice per day, and for more than three seconds on each incisor.

Adolescent↗
PubMedDate not supplied

A comparison of restorations for children with early childhood caries treated under general anesthesia or conscious sedation.

PURPOSE: There is no data in the dental literature concerning the quality of the restorations performed in young children with early childhood caries (ECC) under sedation as compared with those treated under general anesthesia (GA). The aim of this study was to compare the quality of restorations and recurrent caries in 65 children with ECC who had dental treatment under GA or sedation. METHODS: Thirty-four children, mean age 34.4 months were treated under GA and 31 children with a mean age of 37.2 months were treated under sedation and re-examined 6-24 months after completion of treatment. The quality of the restorations was evaluated using a modified Cvar & Ryge index. RESULTS: Fifty-nine percent of children treated under GA required further dental treatment compared to 74% of children treated under sedation. The majority of the required treatment was due to new caries: 57% in the GA group and 60% in the sedation group. A total of 248 restorations were evaluated for the GA group, with a 94% success rate for marginal adaptation, 92% success for anatomic form, and 97% had no secondary caries. In the sedation group, out of 224 restorations, 78% demonstrated perfect marginal adaptation, 79% showed adequate anatomic form, and 90% had no secondary caries. Successful marginal adaptation was found in 90% of strip crowns placed under GA, compared to 63% of those placed under sedation. CONCLUSION: It is concluded that the outcome of treatments related to quality of the restorations performed under GA is better for all parameters examined.

Anesthesia, Dental↗