Gap junctions synchronize the firing of inhibitory interneurons in guinea pig hippocampus.

The convulsant 4-aminopyridine (4AP) facilitates the synchronous firing of interneurons in the hippocampus, eliciting giant inhibitory postsynaptic potentials (IPSPs) in CA3 pyramidal cells. We used the gap junction blocker carbenoxolone to investigate the role of electrotonic coupling in both the initiation and the maintenance of 4AP-facilitated inhibitory circuit oscillations. Carbenoxolone abolished all synchronized IPSPs in CA3 cells elicited by 4AP in the presence of ionotropic glutamate receptor blockers. Carbenoxolone also blocked the isolated synchronized GABA(B) IPSPs generated in CA3 cells by a subpopulation of interneurons. These data confirm that: (1) the interneurons producing GABA(B) responses in CA3 cells are electrotonically coupled, and (2) gap junctions among interneurons are essential for initiating synchronized interneuron oscillatory firing in 4AP.

Information needs and preferences for participation in treatment decisions among Swedish breast cancer patients.

Patient participation in treatment decisions presupposes well-informed patients. The purpose of this study was to determine Swedish breast cancer patients' information needs and their preferences for participation in treatment decisions. Patients (n = 201) were interviewed on nine categories of information and five patient roles, using paired comparisons. Patients gave priority to facts about disease and treatment (chances of cure, stage of disease, treatment options). A collaborative role in treatment decisions was preferred by 87% of the patients. Most patients (56%) preferred a passive form of collaboration: I prefer that my doctor makes the final decision about my treatment but seriously considers my opinion. Younger and better educated patients tended to prefer a more active role. Many patients wanted to be more active (20%) and some more passive (8%) than they actually were. Patients gave priority to disease-specific information, but this reflected needs other than taking control of treatment decisions.

Health-related quality of life measured by the EORTC QLQ-C30--reference values from a large sample of Swedish population.

The EORTC QLQ-C30 Health-Related Quality of Life (HRQOL) questionnaire was completed by 3069/3919 (78%) of a random sample of the Swedish population aged 18-79 years. The aims of the study were to provide normative data on the questionnaire and to investigate differences in HRQOL with respect to age, gender, sociodemographic characteristics and reported chronic health problems. Women had lower scores than men on all but one of the EORTC QLQ-C30 subscales and reported more chronic health problems. The oldest respondents (70-79 years) had a greater degree of impaired HRQOL than the other age groups, with one exception, 'Emotional functioning', in which they scored higher. Unemployed respondents reported poorer HRQOL than employed respondents. Higher income was associated with a more positive assessment of HRQOL. The results of the study present reference values for EORTC QLQ-C30 Version 3 questionnaire and clarify the influence of factors which should be taken into account when planning studies of HRQOL.

Multiple chronic health problems are negatively associated with health related quality of life (HRQoL) irrespective of age.

PURPOSE: To examine HRQoL measured by EORTC QLQ-C30 with respect to an increasing number of self-reported chronic health problems in the general Swedish population and to study the association between HRQoL, chronic health problems and age, gender, income, marital status and employment status. METHOD: A postal survey among a large random sample of 4000 adults aged 18-79 years. The study material contained EORTC QLQ-C30 core questionnaire supplemented by a sociodemographic questionnaire including questions about 13 chronic health problems of which four categories, 'No', 'Few', 'Some' or 'A lot of chronic health problems were constructed. RESULTS: Multiple chronic health problems were significantly associated with reduced HRQoL. The increased number of chronic health problems was also associated with age. When the number of chronic health problems was accounted for, the influence of age diminished. Low income and unemployment were associated with greater decline in HRQoL with respect to increasing number of problems among the respondents in working age. CONCLUSION: The impact of increased number of chronic health problems had varying consequences in different age groups. Moreover, sociodemographic and economic factors showed to interact differently with chronic health problems and HRQoL in various age groups. It appears from our results that an assessment and a careful consideration of these factors will be valuable in order to facilitate the interpretation of the effects of cancer and treatment on long-term HRQoL of cancer patients.

[Retraction of lower limbs in a female with hyperthyroidism]. / Retracción de miembros inferiores en un paciente con hipertiroidismo.

We report a 47 years old woman with hyperthyroidism that had a severe tendinous retraction of hips and knees that subsided with propylthiouracil treatment. Electrodiagnosis showed myopathic alterations and muscle strength was moderately reduced. The authors did not find references of a similar condition in patients with hyperthyroidism.

Synaptic connectivity of distinct hilar interneuron subpopulations.

Dual intracellular recordings of hilar interneurons and CA3 pyramidal cells were performed in transverse slices of guinea pig hippocampus in the presence of the convulsant compound 4-aminopyridine (4-AP) and ionotropic glutamate receptor antagonists. Under these conditions, interneurons burst fire synchronously, producing synchronized inhibitory postsynaptic potentials (sIPSPs) in pyramidal cells. Three different hilar interneuron subpopulations that contributed to the sIPSP were identified based on their projection properties and morphology. These three types were pyramidal-like stellate interneurons, spheroid interneurons, and oviform interneurons. Physiologically, pyramidal-like stellate interneurons could be differentiated from the other interneuron subpopulations because they generated short synchronized bursts of action potentials coincident with the hyperpolarizing and depolarizing gamma-aminobutyric acid-A (GABAA)-mediated inhibitory postsynaptic potentials (IPSPs) recorded in pyramidal cells. The bursts in pyramidal-like stellate cells were abolished by theGABAA-receptor blocker, bicuculline. In contrast, spheroid interneurons of the dentate-hilus (D-H) border and oviform hilar interneurons exhibited prolonged bicuculline-resistant bursts that occurred coincident with the GABAB pyramidal cell sIPSPs. Pyramidal-like stellate interneurons likely did not contribute to the generation of synchronized GABAB responses in hippocampal pyramidal cells. Spheroid interneurons were unique among these subpopulations of interneurons in that the bicuculline-resistant bursts in spheroid interneurons were sustained by a synaptic depolarization that persisted in the presence of antagonists of ionotropic glutamate, GABAA and GABAB receptors [6-cyano-7-nitroquinoxaline-2,3-dione, 20 microM; 3-3(2-carboxipiperazine-4-yl)propyl-1-phosphonate, 20 microM; bicuculline, 10-15 microM; CGP 55845A, 20 microM]. This novel depolarizing potential reversed between -30 and 0 mV. No noticeable synaptic depolarization sustaining burst firing could be isolated in oviform interneurons, suggesting that firing in this interneuron subpopulation was synchronized by nonsynaptic mechanisms. The results of the present study indicate that the hilar inhibitory circuit is composed of at least three different subpopulations of interneurons, distinguishable by their morphological characteristics and synaptic inputs and outputs. These findings give further support to the hypothesis that there are distinct populations of interneurons producing GABAA and GABAB responses with defined functional roles within the hippocampal inhibitory circuit. Notably, we found that spheroid interneurons were unique among the hilar interneurons studied, in that the synchronized bursts observed in these cells are sustained by a novel ionotropic glutamate and GABA receptor-independent synaptic depolarization.

Novel glutamate- and GABA-independent synaptic depolarization in granule cells of guinea-pig hippocampus.

1. Dual intracellular recordings of granule cells, hilar interneurons and CA3 pyramidal cells were performed in transverse slices of guinea-pig hippocampus. At resting membrane potential, in the presence of 4-aminopyridine, ionotropic glutamate receptor antagonists and the GABAA receptor antagonist bicuculline, granule cells showed spontaneous, large amplitude depolarizations correlated with synchronous bursting activity of interneurons. 2. Under these conditions, pyramidal cells exhibited large amplitude monophasic GABAB inhibitory postsynaptic potentials (IPSPs) synchronous with the GABAergic interneuron burst discharges. The granule cells also received a GABAB input, which was evident only when the neurons were depolarized by DC injection. The GABAB receptor antagonist CGP 55,845A (CGP) blocked the GABAB IPSPs in both pyramidal cells and granule cells; however, the depolarizing potential in granule cells was unaffected by the drug. 3. The granule cells depolarization in the presence of CGP was monophasic and exhibited linear voltage dependence with a reversal potential around -40 mV, suggesting that it was generated by a synaptic input activating a mixed cationic current. 4. The granule cell depolarization was abolished following the addition of tetrodotoxin to the bath. In addition, perfusing the slice with a low Ca(2+)-containing solution (0.5 mM Ca(2+)-10 mM Mg2+) also abolished the granule cell depolarization, confirming the synaptic origin of the event. 5. (S)-Methyl-4-carboxyphenylglycine, L-(+)-2-amino-3-phosphonopropionic acid, propranolol and atropine did not affect the granule cell depolarization, indicating that metabotropic glutamate receptors, beta-adrenergic receptors and muscarinic cholinergic receptors were not involved in generating the granule cell depolarizing synaptic response. 6. These findings indicate that, in the absence of both glutamatergic and GABAergic inputs, synchronous interneuronal activity can produce a depolarizing synaptic response in granule cells. The neurochemical responsible for the depolarization is currently under investigation.

Repair of rupture of the distal tendon of the biceps brachii. Review of the literature and report of three cases treated with a single anterior incision and suture anchors.

Operative repair of distal biceps tendon ruptures is recommended for active individuals desiring maximum return of elbow supination and flexion power and endurance. Traditional two-incision repair methods are highly successful, but they carry the risk of radioulnar synostosis formation if the ulna is exposed. Repair via an anterior incision through bone drill holes requires more dissection and potential risk to the posterior interosseous nerve. The authors present a method of repair of distal biceps tendon ruptures via a single anterior incision using suture anchors. This technique has been used in 3 patients with excellent functional results and is recommended for use as an alternative to the two-incision method.

Six-month follow-up of effects of an information programme for patients with malignant melanoma.

Using a randomized design, the effects of an information programme for melanoma patients were studied. The programme consisted of a group meeting and a brochure. The present study reports on the six-month follow-up of the effects of the programme. A total of 128 patients participated in the programme, 55 before and 73 after the first medical control visit. Questionnaires regarding knowledge about melanoma, psychological and psychosomatic variables were completed at the first medical control visit and six months later by mail. A questionnaire concerning patients attitudes to the programme was included after six months. Knowledge about melanoma increased and a majority of patients were satisfied with the information brochure, the group meeting and the group leader, but 40% considered that too few participants attended in their group meeting. No effects on psychological or psychosomatic variables were found. Men and women participated to the same extent.

Perceived susceptibility to and knowledge of malignant melanoma: screening participants vs the general population.

BACKGROUND: The incidence of and mortality from melanoma are increasing and no effective treatment for disseminated disease exists. Studies of factors influencing participation in prevention and early detection of melanoma are therefore warranted. In the present study, participants in public melanoma screening were compared with a sample of the Swedish population with respect to concern for nevi, perceived risk for melanoma, knowledge about melanoma, and sources of information. Gender differences were studied. METHOD: Consecutive participants in public melanoma screening (Participants) received questionnaires at registration for skin examination; 235 (96%) responded. Questionnaires were distributed by mail to a random sample of the Swedish population (Public); 1,070 (63%) responded. RESULTS: Participants were more concerned about nevi, and a higher proportion had previously consulted physicians for suspected lesions compared with the Public. Participants were better informed in terms of the number of sources of information and knowledge of melanoma and risk factors. There were no differences regarding perceived risk and there was a mixed picture concerning knowledge of sun effects and sun protection. Gender differences were found for perceived susceptibility to, knowledge of, and number of sources of information about melanoma, favoring women. CONCLUSION: The preventive aspects of screening as well as the good prognosis of melanoma detected early should be stressed in invitations to skin cancer screening. New approaches for reaching men are warranted.

Synchronization of inhibitory neurones in the guinea-pig hippocampus in vitro.

1. Intracellular recordings were obtained from pyramidal, granule and hilar cells in transverse slices of guinea-pig hippocampus to examine synaptic interactions between GABAergic neurones. 2. In the presence of the convulsant compound 4-aminopyridine (4-AP), after fast excitatory amino acid (EAA) neurotransmission was blocked pharmacologically, large amplitude inhibitory postsynaptic potentials (IPSPs) occurred rhythmically (every 4-8 s) and synchronously in all principal cell populations (triphasic synchronized IPSPs). In the presence of the GABAA receptor blocker picrotoxin (PTX), a large amplitude IPSP continued to occur spontaneously in all principal cells simultaneously (monophasic synchronized IPSP). 3. Burst firing occurred simultaneously in a group of hilar neurones (synchronized bursting neurones) coincident with triphasic synchronized IPSPs in principal cells. After PTX was added, the bursts and the underlying depolarizing synaptic potentials were completely suppressed in some of the synchronized bursting neurones (type I hilar neurones), while others (type II hilar neurones) continued to fire in bursts coincident with monophasic synchronized IPSPs in principal cells. Intense hyperpolarization blocked burst firing and revealed underlying attenuated spikes of less than 10 mV, but did not uncover any underlying depolarizing synaptic potentials. 4. In type II hilar neurones, during sufficient hyperpolarization, spontaneous activity consisted of attenuated spikes. With depolarization, the small spikes began to trigger full size action potentials. These data suggest the presence of electrotonically remote spike initiation sites. 5. The morphology of synchronized bursting neurones was revealed by intracellular injection of the fluorescent dye Lucifer Yellow. Attempts to inject dye into one type II hilar neurone often resulted in the labelling of two to four cells (dye coupling). Dye coupling was not observed in type I hilar neurones. 6. These findings indicate that excitatory interactions synchronizing the firing of GABAergic neurones can occur in the absence of fast EAA neurotransmission. GABAergic neurones can become synchronized via their recurrent collaterals through the depolarizing action of synaptically activated GABAA receptors. In addition, a subpopulation of GABAergic neurones can become synchronized by a mechanism probably involving electrotonic coupling.

Information to patients with malignant melanoma: a randomized group study.

An information programme for patients with cutaneous malignant melanoma, Stage 1, aiming at increasing satisfaction with information, was carried out at the Department of Oncology (Radiumhemmet). The programme consisted of a group meeting and a brochure. A total of 231 consecutive patients were included, and 149 (65%) reported interest in participation and were randomized to the Information group (n = 77) or to the Control group. A total of 67 patients (29%) were not interested (the NI-group). To evaluate the programme, the patients in the three groups completed questionnaires regarding satisfaction with information, knowledge of melanoma and psychological and psychosomatic variables before randomization and at the first visit for follow-up at Radiumhemmet. After the information programme, the Information group was significantly more satisfied with information, had a higher level of knowledge and a lower proportion requested further information as compared with the Control group. No differences were found on the psychological and psychosomatic variables.

Psychological reactions in public melanoma screening.

Participants in public screening for malignant melanoma (n = 190) completed a questionnaire containing items regarding cognitive and emotional responses to skin examination on two occasions, before screening and 7 months later. The results suggest subjective susceptibility to melanoma in participants in public screening, especially in women. No increase in psychosomatic problems, anxiety or depressive symptoms or signs of "false security" were seen as an effect of the screening, neither in the total sample nor in those who at the screening were recommended further medical procedures.

Ontogeny of epileptogenesis in the rat hippocampus: a study of the influence of GABAergic inhibition.

In vivo experiments were carried out to examine whether the period during which gamma-aminobutyric acid (GABA)ergic inhibition in the hippocampus matures is associated with a decrease in epileptogenesis. Seizures were elicited with bipolar electrodes stereotactically positioned in the hippocampus of urethane-anesthetized rat pups from postnatal (PN) 7 through 28 days of age. No clinical seizure activity was detected but electrographic seizures (afterdischarges) were induced at all ages. Afterdischarge thresholds (ADT) varied inversely with age. However, the durations of initial afterdischarges and the degree of lengthening of afterdischarges with the rapidly recurring hippocampal seizure (RRHS) protocol were not different for the various age animals studied. Paired pulse inhibition was assessed with a twin pulse paradigm that has been shown to monitor GABAergic inhibition. Measurements were made before and 60 min after a single seizure and again 60 min after the RRHS protocol. At no age was there a significant change in paired pulse inhibition after a single seizure. After RRHS there was a significant reduction of paired pulse inhibition only in the groups that had manifested adult levels of paired pulse inhibition in pre-seizure measurements (greater than or equal to PN 21). These studies indicate that heightened epileptogenesis in the young hippocampus cannot simply be explained on the basis of an immaturity of GABA-mediated inhibition.

Excitatory synaptic responses mediated by GABAA receptors in the hippocampus.

Gamma-aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the cortex. Activation of postsynaptic GABAA receptors hyperpolarizes cells and inhibits neuronal activity. Synaptic responses mediated by GABAA receptors also strongly excited hippocampal neurons. This excitatory response was recorded in morphologically identified interneurons in the presence of 4-aminopyridine or after elevation of extracellular potassium concentrations. The synaptic excitation sustained by GABAA receptors synchronized the activity of inhibitory interneurons. This synchronized discharge of interneurons in turn elicited large-amplitude inhibitory postsynaptic potentials in pyramidal and granule cells. Excitatory synaptic responses mediated by GABAA receptors may thus provide a mechanism for the recruitment of GABAergic interneurons through their recurrent connections.

A model of a CA3 hippocampal pyramidal neuron incorporating voltage-clamp data on intrinsic conductances.

1. We have developed a 19-compartment cable model of a guinea pig CA3 pyramidal neuron. Each compartment is allowed to contain six active ionic conductances: gNa, gCa, gK(DR) (where DR stands for delayed rectifier), gK(A), gK(AHP), and gK(C). THe conductance gCa is of the high-voltage activated type. The model kinetics for the first five of these conductances incorporate voltage-clamp data obtained from isolated hippocampal pyramidal neurons. The kinetics of gK(C) are based on data from bullfrog sympathetic neurons. The time constant for decay of submembrane calcium derives from optical imaging of Ca signals in Purkinje cell dendrites. 2. To construct the model from available voltage-clamp data, we first reproduced current-clamp records from a model isolated neuron (soma plus proximal dendrites). We next assumed that ionic channel kinetics in the dendrites were the same as in the soma. In accord with dendritic recordings and calcium-imaging data, we also assumed that significant gCa occurs in dendrites. We then attached sections of basilar and apical dendritic cable. By trial and error, we found a distribution (not necessarily unique) of ionic conductance densities that was consistent with current-clamp records from the soma and dendrites of whole neurons and from isolated apical dendrites. 3. The resulting model reproduces the Ca(2+)-dependent spike depolarizing afterpotential (DAP) recorded after a stimulus subthreshold for burst elicitation. 4. The model also reproduces the behavior of CA3 pyramidal neurons injected with increasing somatic depolarizing currents: low-frequency (0.3-1.0 Hz) rhythmic bursting for small currents, with burst frequency increasing with current magnitude; then more irregular bursts followed by afterhyperpolarizations (AHPs) interspersed with brief bursts without AHPs; and finally, rhythmic action potentials without bursts. 5. The model predicts the existence of still another firing pattern during tonic depolarizing dendritic stimulation: brief bursts at less than 1 to approximately 12 Hz, a pattern not observed during somatic stimulation. These bursts correspond to rhythmic dendritic calcium spikes. 6. The model CA3 pyramidal neuron can be made to resemble functionally a CA1 pyramidal neuron by increasing gK(DR) and decreasing dendritic gCa and gK(C). Specifically, after these alterations, tonic depolarization of the soma leads to adapting repetitive firing, whereas stimulation of the distal dendrites leads to bursting. 7. A critical set of parameters concerns the regulation of the pool of intracellular [Ca2+] that interacts with membrane channels (gK(C) and gK(AHP)), particularly in the dendrites.(ABSTRACT TRUNCATED AT 400 WORDS)

An ontogenetic study of kindling using rapidly recurring hippocampal seizures.

The present study investigated the acquisition and retention of kindling in immature rats. Postnatal (PN) 7-28-day-old rats were electrically kindled in the ventral hippocampus. Ten-second, 20-Hz stimulus trains were delivered every 5 min for 6 h on one day (short interval rapidly recurring hippocampal seizures, RRHS) or every 30 min for 9 h on each of two consecutive days (long interval RRHS). Afterdischarge durations (ADD) and behavioral seizure scores (BSS) were recorded following each stimulation. Animals of all ages kindled with both short and long interval RRHS, as manifested by lengthening of ADD and increasing BSS. With short interval RRHS, the course of kindling was erratic; with long interval RRHS, kindling proceeded smoothly over both test days. In PN 14-28 rats, the degree of kindling obtained on the first day of long interval RRHS was retained at the start of the second experimental day. In contrast, PN 7 rats showed a transient decrease in ADD and BSS from day 1 to day 2. Afterdischarge thresholds declined with maturation. Among the PN 14-28 animals, younger rats exhibited longer seizures at the outset of kindling and proceeded through kindling faster. Once established, kindled motor seizures also occurred with 2-s, 50-Hz stimulus trains. We conclude that rapid kindling occurs at all ages; however, PN 7 rats are less capable of retaining the kindling effect than are older rats.

Synchronized GABAergic IPSPs recorded in the neocortex after blockade of synaptic transmission mediated by excitatory amino acids.

1. Intracellular and extracellular recordings were carried out in guinea pig neocortical slices to examine the effects of blockade of excitatory amino acid (EAA) synaptic transmission on population discharges elicited by 4-aminopyridine (4-AP; 50-100 microM). 2. After the introduction of 4-AP, two distinct types of rhythmic spontaneous field potentials were recorded in neocortical slices. Type I consisted of multiple spike discharges lasting 20-90 s. These events occurred at a frequency of 0.4-0.2/min. Type II were single field potential spikes (3-6 s in duration) occurring at a higher frequency (2-4/min). 3. Blockade of amino acid-mediated excitatory synaptic transmission with D-2-amino-5-phosphonovaleric acid (D-AP5; 10-30 microM) or 3-(2-carboxypiperazin-4-yl)propyl-l-phosphonic acid (CPP, 10 microM) and 6-cyano-7nitroquinoxaline-2,3-dione (CNQX; 10 microM) abolished the first type of 4-AP-induced field potential, whereas type II events persisted. 4. Type II field events, occurring in the presence of EAA blockers, were further characterized by paired recordings. Events recorded along an axis orthogonal to the pia surface occurred simultaneously without measurable delay. Recordings made along a plane parallel to the pia surface showed that type II discharges propagated over distances of greater than or equal to 3 mm at an estimated velocity of 7.5 mm/s. 5. Intracellular recordings show that during type II field discharges all cells exhibited phasic depolarizations or hyperpolarizations, depending on the resting membrane potential. When resting potentials were more depolarized than -68 mV, events became mostly hyperpolarizing.(ABSTRACT TRUNCATED AT 250 WORDS)