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Biomedical subjects

M Laufer

Publications and source records attributed to M Laufer.

At least 19 recordsLinked to original sources
PubMed1994

Sexual abuse, or a delusional structure? From adolescent to young adult.

The treatment of an adolescent patient who recalled having been sexually abused in childhood by her father is described. In the course of treatment, various doubts were raised in the analyst's mind about the truth of this memory. As the analysis progressed, the analyst felt that the patient's responses to interpretations were signs of the presence of a delusional structure. When the patient felt that the analyst doubted her memory, or was not on her side, she angrily and vengefully broke off her treatment. She remains a very vulnerable young woman. The delusional structure contained the patient's sexual need to destroy the male's potency as a defense against her longing for the oedipal mother who, in reality, had left the patient for a new husband.

Adolescent↗
PubMed1994

[Relevance of alfentanil as an analgesic in N20 supplemented intravenous anesthesia in ambulatory surgery].

Alfentanil is a suitable analgesic drug for nitrous oxide-supplemented intravenous anaesthesia in day case surgery--provided that the appropriate requirements are taken into consideration. Following the last bolus dose of alfentanil the plasma concentration decreased below the threshold plasma concentration for respiratory depression of 100 to 300 ng/ml alfentanil within 5 to 10 minutes. The patients showed rapid recovery from anaesthesia and were cooperative shortly after discontinuation of the intravenous drug administration. Two to three hours postoperatively there was hardly any evidence of residual impairment due to the anaesthetic. Early postoperative pain relief was required.

Adolescent↗
PubMed1993

[Modulation of electrical coupling of horizontal cells of the retina].

Horizontal cells are electrically coupled in the teleost retina. This coupling is modulated by dopamine, which is in turn liberated from interplexiform amacrine cells. The present review includes studies carried out to elucidate the intracellular mechanisms responsible for such modulation of the resistance of intercellular unions, that results from the action of dopamine on receptors located on the cell membrane. In order to study the effects of possible second messengers, hydrogen ions (H+), cyclic adenosine monophosphate (cAMP) or calcium ions (Ca2+) were injected electrophoretically from multiple microelectrodes that simultaneously allow for voltage recording in the injected cells and in neighboring ones. A resistive hexagonal network model was used to calculate the cell membrane resistance (Rm) and the coupling resistance (Ra) between the two impaled cells. Intracellular injections of Lucifer yellow were used to microscopically verify the changes produced in Ra. The microinjection of either H+ or cAMP led to reduction in coupling ratio and increase in Ra, while Rm was reduced. These changes are similar to those produced by dopamine perfusion of the retina and, equally, are corroborated by the hindrance of diffusion to neighboring cells of the Lucifer yellow injected simultaneously. No changes were detected upon Ca2+ injection, but the chelator EGTA resulted in an increased electrical coupling and Rm reduction. The results reported are consistent with the idea that both H+ and cAMP are second messengers involved in dopamine's modulation of intercellular coupling, which is produced by changes in the resistance of intercellular unions, while Ca2+ would act as a modulator through its effect on the cell membrane resistance.

Animals↗
PubMed1990

Retinal neurotransmitter interaction as reflected in horizontal cell spatial behaviour.

The effects of 5-hydroxytryptamine (5-HT) and its precursors 5-hydroxytryptophan (5-HTP) and L-tryptophan (L-Tryp) on the spatial properties of horizontal cells were studied in the isolated and perfused retina of the teleost Eugerres plumieri. All three compounds produce a contraction of the receptive field, evaluated by the ratio of responses evoked by local and distant light stimuli. This is the result of cell uncoupling, revealed by the hindrance to diffusion of intracellularly injected Lucifer yellow. Similar effects are produced by dopamine (DA) and the effectiveness is DA much greater than 5-HT greater than 5-HTP greater than L-Tryp. All these effects are blocked by Haloperidol. HPLC studies of endogenous DA release reveal that it occurs when isolated retinas are incubated with 50 mM potassium, 10 microM 5-HT or 5-HTP, but is not found with up to 1 mM L-Tryp. The results indicate that indolaminergic cells induce the release of DA from interplexiform cells, which in turn uncouples horizontal cells in the fish retina.

5-Hydroxytryptophan↗
PubMed1989

Cyclic adenosine monophosphate as a second messenger in horizontal cell uncoupling in the teleost retina.

The reduction in the receptive field of horizontal cells of the teleost Eugerres plumieri observed upon dopamine (DA) superfusion is thought to be due to cell uncoupling. The possible mechanisms by which activation of DA receptors modify the electric coupling between horizontal cells were studied in the present work. It was found that the effect of DA in different preparations is mediated by a modification of intracellular concentration of cAMP and H+. The effects of intracellular injection of cAMP and H+ were studied in retinal horizontal cells of the teleost E. plumieri. A triple microelectrode was used to inject the ion iontophoretically, to pass current pulses, and to record voltages from the same cell, while a fourth microelectrode was used to record voltages from a neighboring cell in the same retinal layer. Responses evoked by light spots and annuli were evaluated simultaneously. Coupling ratios between neighboring horizontal cells ranged from 0.22 to 0.45. The intercellular resistance (Rc), 0.5-3.5 x 10(6) ohms, and that of the remaining cell membrane resistance (Rm), 2.5-18 x 10(6) ohms, were calculated by means of a passive electrical model that has a hexagonal array. The microinjection of H+ with injection current from +5 to +30 nA for 40 to 100 sec led to temporary and reversible light response reduction. The coupling ratio between two impaled cells was reduced by about 30%, and intercellular resistance (Rc) increment was 320% while cell membrane resistance (Rm) did not change consistently. There was also a temporary and reversible Rm reduction (70-85%) and an Rc increment of 170-330% when cyclic adenosine monophosphate was iontophoretically injected with current from -30 to -40 nA for 50 to 170 sec. The coupling ratio between two impaled cells was reduced by about 40%, and light responses recorded from the injected cell showed a reduction in amplitude with the same time course as that of the resistive changes. The injection of Lucifer yellow into a horizontal cell under normal conditions always results in pronounced fluorescence for more distant cells; however, under constant injection of H+ or cAMP only the injected cell is fluorescent, which provides direct evidence of the reduction in the effectiveness of coupling between horizontal cells. The observed effects of intracellular H+ or cAMP injection correspond to the resistive changes in Rc and coupling ratio that occur in the horizontal cell network upon superfusion with a dopamine (DA) solution.

Animals↗
PubMed1986

Adolescence and psychosis.

In this paper, I discuss how the specific developmental function of adolescence can result in behaviour and thought which resemble the adult psychoses but which, in most circumstances, are fundamentally different from the adult psychoses. Anybody who treats the seriously disturbed adolescent will be familiar with a simple and obvious characteristic of these adolescents--it is an irreconcilable, unanswerable quest to alter the image of the body. If we try to understand the psychotic manifestations or psychoses of adolescence, we must differentiate between (i) a psychotic episode, (ii) psychotic functioning, and (iii) psychosis. The assessment of psychosis must be reserved only for a very special category of disorder in adolescence and must not be confused with either a psychotic episode or psychotic functioning.

Adolescent↗
PubMed1983

Fine structure of regenerated ependyma and spinal cord in Sternarchus albifrons.

The caudal-most regenerated spinal cord in Sternarchus albifrons consists solely of an ependymal tube. Ependymal cells are enlarged radially and are more numerous than in unregenerated cord. Projections of ependymal cell cytoplasm and Reissner's fiber fill most of the central canal. Small groups of neurites and cell processes filled with dense-cored vesicles lie between abluminal processes of ependymal cells. Rostral to this, additional cells appear dorsal and lateral to the inner ependymal layer. Some cell bodies contain numerous dense-cored vesicles. Larger bundles of neurites, some with synapses, are present. Invaginations of the peripheral edge of the cord create enclosed spaces lined with basal lamina. In the peripheral region, longitudinally oriented neurites extend through extracellular spaces or channels. The ventral portion at some levels of regenerated cord is completely filled with neurites, processes containing dense-cord vesicles, and capillaries. Similar masses of neurites and processes containing dense-cored vesicles lie outside the cord proper, in or near the meningeal layer. In rostral-most sections, the organization of regenerated spinal cord approaches that of normal cord, with the regenerated cord exhibiting groups of myelinated axons, differentiated fibrous astrocytes and oligodendroglia, cell bodies containing dense-cored vesicles, and differentiated electromotor neurons. These observations indicate a degree of pluripotency in some of the ependymal cells in adult Sternarchus. Moreover, they are consistent with a role of ependymal cells in the guidance of regenerating neurites.

Animals↗
PubMed1982

The formation and shaping of the Oedipus complex: clinical observations and assumptions.

Freud maintained that the Oedipus complex as a development landmark could be conceptualized as taking place only at the time of the phallic phase. Freud's theory is that it is the culmination of a very long process whose primary result, in developmental terms, was that the ego now had to act as an organizing and unifying agent of all of one's past, while at the same time adding a new agency of the mind which he called the superego. With the resolution of the Oedipus complex, infantile sexuality would begin to be left behind. Since Freud, there have been a number of developments and controversies related to the Oedipus complex. The confusion which has arisen is that some of us use the insights we have gained about pre-oedipal life as themselves holding the answers to many of the psychopathologies we meet with clinically. My own view is that unless these insights about pre-oedipal life become part of a development framework, culminating in the Oedipus complex and, through its resolution, in the internalization of the superego, then we miss something which is fundamental in our understanding and in our efforts to undo psychopathology. For Freud, the relationship between sexuality and the Oedipus complex was inseparable. The assumption I put forward about the Oedipus complex is that the image of one's own body which has been organized by the end of the phallic-oedipal period determines the form of the oedipal resolution, and remains central to one's later sexual life and psychopathology. If, in our clinical work, we avoid the meaning of genital sexuality and the meaning of the sexual body image, but interpret mainly those aspects of the patient's life which are pre-oedipal (and therefore non-incestuous), then we lose the chance of creating the possibility of the patient having an active relationship to his sexual/genital body, and the patient loses the chance of ever feeling himself to be the owner of his own sexuality.

Adolescent↗