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Biomedical subjects

J K Meyer

Publications and source records attributed to J K Meyer.

At least 19 recordsLinked to original sources
PubMed1996

Mapping motor neuron activity to overt behavior in the leech. I. Passive biomechanical properties of the body wall.

As an initial step in constructing a quantitative biomechanical model of the medicinal leech (Hirudo medicinalis), we determined the passive properties of its body wall over the physiological range of dimensions. The major results of this study were: 1. The ellipsoidal cross section of resting leeches is maintained by tonic muscle activation as well as forces inherent in the structure of the body wall (i.e., residual stress). 2. The forces required for longitudinal and circumferential stretch to maximum physiological dimensions were similar in magnitude. Cutting out pieces of body wall did not affect the passive longitudinal or circumferential properties of body wall away from the edges of the cut. 3. The strain (i.e., the percentage change in dimension of different body segments when subject to the same force was identical, despite differences in muscle cross-sections. 4. Serotonin, a known modulator of tension in leech muscles, affected passive forces at all physiological muscle lengths. This suggests that the longitudinal muscle is responsible for at least part of the passive tension of the body wall. 5. We propose a simple viscoelastic model of the body wall. This model captures the dynamics of the passive responses of the leech body wall to imposed step changes in length. Using steady-state passive tensions predicted by the viscoelastic model we estimate the forces required to maintain the leech at any given length over the physiological range.

Animals↗
PubMed1992

Cytotoxicity of Bacillus piliformis.

Seven isolates of B. piliformis, the agent of Tyzzer's disease, obtained from various host species, were examined for cytotoxic activity by incubating culture filtrates on BRL 3A rat-hepatocyte and 3T3 mouse-fibroblast cell lines. One isolate exhibited cytopathic effects on BRL 3A cells, but not on 3T3 cells. Three other isolates were strongly cytotoxic for 3T3 cells but only slightly so for BRL 3A cells. The remaining three isolates showed no cytotoxicity for either cell line. The cytotoxic products were greater than 100 kDa in mol. wt, thermolabile, and partly destroyed by trypsin treatment. The data show that some B. piliformis isolates produce cytotoxic proteins, which may contribute to the pathogenesis of Tyzzer's disease.

Animals↗
PubMed1991

Detection of serum antibodies to Bacillus piliformis in mice and rats using an enzyme-linked immunosorbent assay.

Rats and mice were infected with Bacillus piliformis organisms at a dosage which resulted in clinical signs of Tyzzer's disease in gerbils. Although rats and mice did not show clinical signs of disease, rising antibody titers to B. piliformis were detected by enzyme-linked immunosorbent assay (ELISA) 2 to 6 weeks post-inoculation and remained at positive levels 11 weeks post-inoculation. Western blot analyses of sera from experimentally infected animals revealed banding patterns nearly identical to those obtained using hyperimmune serum. Results indicated that elevated ELISA titers reflected production of specific antibodies directed against antigens of B. piliformis. ELISA and Western blot analyses of naturally infected animals yielded similar results. These findings suggest that immunoassays such as ELISA can be used to detect subclinically infected rats and mice in the absence of clinical signs or histopathologic evidence of Tyzzer's disease.

Animals↗
PubMed1988

A case of hysteria, with a note on biology.

Psychoanalysis recently has shown interest in the data of neurobiology. This interest has been fostered by the realization that a model of Cartesian mind-body dualism is inadequate to current observation and knowledge. Despite the theoretical appeal of integrating knowledge from the two fields, there have been few attempts at correlation in specific clinical situations. This paper presents a case of hysteria in which the physical manifestations of hyperprolactinemia, galactorrhea, amenorrhea, and infertility are considered in relation to both the brain regulation of prolactin and to unconscious fantasy, motivation, and conflict. Some of the intriguing possibilities and limitations of research at the frontier of psychoanalysis and neurophysiology are discussed.

Adult↗
PubMed1986

Sexual dysfunction within an adult developmental perspective.

The focus of this paper is on the adult who has adequately mastered the oedipal stage of psychosexual development and who presents with a sexual dysfunction. Drawing on the developmental sequence of Erik Erikson, the authors suggest that failure to address adequately an adult psychosocial crisis may result in sexual dysfunction. There may be both adult developmental deficits and regression to adolescent and adult stages previously negotiated. Both may be symptomatically represented by sexual dysfunction. The authors urge that the sexual and marital problems be evaluated within an adult developmental framework and that the therapy address the psychosocial issues which are appropriate to the developmental stage of the patient.

Adolescent↗
PubMed1985

Psychiatric diagnosis and psychological symptoms in impotence.

A sample of 137 males who presented with a principal complaint of impotence were assessed regarding manifest psychopathology through DSM-III psychiatric diagnosis and the SCL-90-R, a self-report symptom inventory. Contrasts in self-reported symptoms among dysfunctional groups assigned different DSM-III diagnoses proved to be very significant, as were contrasts with patients free of current psychiatric diagnoses. When the sample was separated into the three groups of organic etiology, psychogenic etiology with psychiatric diagnosis, and psychogenic etiology without psychiatric diagnosis, few significant differences in group profiles were uncovered. Findings of the study lend strong support to the notion that males with erectile sexual dysfunction reveal disproportionate levels of psychological symptoms and psychopathology. The results failed to confirm the premise that biogenic versus psychogenic etiologies in impotence can be effectively identified solely on the basis of the psychological symptom picture.

Adjustment Disorders↗
PubMed1982

The theory of gender identity disorders.

Experience with more than 500 patients over the last decade has led to the conclusion that the quest for sex reassignment is a symptomatic compromise formation serving defensive and expressive functions. The symptoms are the outgrowth of developmental trauma affecting body ego and archaic sense of self and caused by peculiar symbiotic and separation-individuation phase relationships. The child exists in the pathogenic (and reparative) maternal fantasy in order to repair her body image and to demonstrate the interconvertability of the sexes. Gender identity exists not as a primary phenomenon, but in a sense as a tertiary one. There is, no doubt, a tendency to gender-differentiate in a way concordant with biological endowment. Nevertheless, gender formation is seriously compromised by earlier psychological difficulty. Gender identity is a fundamental acquisition in the developing personality, but it is part of a hierarchical series beginning with archaic body ego, early body image, and primitive selfness, representing their extension into sexual and reproductive spheres. Gender identity consolidates during separation-individuation and gender pathology bears common features with other preoedipal syndromes. Transsexualism is closely linked to perversions, and the clinical syndromes may shade from one into another. However, what is kept at the symbolic level in the perversions must be made concrete in transsexualism. In this regard there is a close relation to psychosis. The clinical complaint of the transsexual is a condensation of remarkable proportions. When the transsexual says that he is a girl trapped in a man's body, he sincerely means what he says. As with other symptoms, however, it takes a long time before he begins to say what he means.

Animals↗
PubMed1981

A psychological profile of the transsexual. II. The female.

This research introduced standardized psychological measurement into the clinical assessment of the female transsexual. Twenty females with a presenting complaint of gender dysphoria were carefully screened to ensure high correspondence between their clinical pictures and current nosological concepts of transsexualism. All were administered the Derogatis Sexual Functioning Inventory as a part of their initial clinical work-up, and their profiles were contrasted with those of a comparison group of 143 heterosexual females. Results indicated hypermasculine gender role definitions and fantasy themes among the transsexual group with decrements in terms of sexual information and range of sexual experiences. The transsexual females revealed moderately dysphoric affect profiles but were unremarkable in terms of psychological symptoms. Overall, there was evidence of reductions in sexual drive; however, this result was highly dependent upon which indicator of drive was employed. The opportunity to obtain a systematic psychometric evaluation of this fascinating clinical group is viewed as a significant step in gaining an ultimate understanding of their condition.

Adult↗
PubMed1981

Psychopathology in individuals with sexual dysfunction.

The literature contains contradictory reports on the psychiatric status of individuals with sexual dysfunction. As a step toward resolving the controversy the authors administered the SCL-90-R to a large series of patients who sought treatment for sexual disorders (N = 325). Psychiatric evaluations were also done for each patient. Results showed disproportionate levels of psychological distress, reflected in SCL-90-R symptom profiles; approximately one-third of the 199 men and one-half of the 126 women in the series were also assigned psychiatric diagnoses. Findings provided evidence suggesting that the various sexual dysfunctions have characteristic symptom profiles; however, interpretation should be cautious because the cause-and-effect relationship between psychological distress and sexual dysfunctions remains complex and uncharted.

Adjustment Disorders↗
PubMed1981

Partners of distressed transvestites.

The authors studied partners of 18 transvestites who sought consultation because of their disorder. They found that all of these women were moral masochists and that all tolerated the self-centered, obsessive-compulsive behavior of their transvestic spouses. Many of these women had experienced multiple losses and poor parenting, and their transvestic partners fulfilled their dependency needs. The authors recommend supportive and insight-oriented therapy for such women who, in order to stay with a transvestic man, sacrifice their own self-esteem and desire to engage in a mutual relationship.

Adult↗
PubMed1980

The border area between transvestism and gender dysphoria: transvestitic applicants for sex reassignment.

Clinical variants among the population of applicants for sex reassignment have been previously categorized. These coherent entities were introduced in an effort to sharpen the clinical presentation of syndromic diversity as well as to enhance the specificity of prognosis and outcome. The description of the so-called younger and aging transvestite has been further investigated. Although the initial group of reported transvestitic patients was small, it was suggested that these individuals constituted a coherent group definable in terms of demographic variables, past history, current crises, psychodynamics, clinical course, and special risks. This investigation presents a supplementary series of aging and younger transvestites who have applied for sexual reassignment. Since the original report, further elucidation of the characteristics of both groups have emerged. The theoretical implications of these categories have become clearer. The data support the original content of the classification as an aid to evaluation, prognosis, and treatment.

Adult↗
PubMed1980

Transvestism: previous findings and new areas for inquiry.

The transvestite is a heterosexual fetishistic cross-dresser. The phenomenology of the disorder reveals individuals to be heterosexual males who have usually married and fathered children. The course of the disorder is unknown. Many transvestites note genital arousal from cross-dressing abates, yet continue episodically to wear women's clothes. A small segment of these individuals become gender dysphoric and seek sexual reassignment. Etiologic explanations include pregenital psychopathology in the genesis of the condition. The treatment for transvestism remains disappointing although behavior modification may offer individuals who wish to change their transvestitic behavior some hope. This review suggests new areas for inquiry and possible research strategies.

Adolescent↗
PubMed1979

Sex reassignment. Follow-up.

Although medical interest in individuals adopting the dress and life-style of the opposite sex goes back to antiquity, surgical intervention is a product of the last 50 years. In the last 15 years, evaluation procedures and surgical techniques have been worked out. Extended evaluation, with a one- to two-year trial period prior to formal consideration of surgery, is accepted practice at reputable centers. Cosmetically satisfactory, and often functional, genitalia can be constructed. Less clear-cut however, are the characteristics of the applicants for sex reassignment, the natural history of the compulsion toward surgery, and surgery's long-term effects. The characteristics of 50 applicants for sex reassignment, both operated and unoperated, are reported in terms of such indices as job, education, marital, and domiciliary stability. Outcome are reviewed. The results of long-term follow up data are discussed in terms of the adjustments of operated and unoperated patients.

Adult↗
PubMed1979

A psychological profile of the sexual dysfunctions.

The present report summarizes an assessment of the psychological characteristics of a sample of sexually dysfunctional patients and compares them to those of a sample of heterosexual normals. Forty-seven male and 40 female dysfunctional patients were evaluated on the Derogatis Sexual Functioning Inventory (DSFI) and contrasted to a group of 200 heterosexual normals. Findings indicated substantial differences between dysfunctionals and normals on seven of the eight subtests of the DSFI. Both male and female patients showed higher levels of psychological distress and dysphoric affect than normals, and also revealed decrements on sexual information. Particularly noteworthy among male dysfunctionals were lowered sexual drive levels and a somewhat constricted repertoire of sexual experiences. Male dysfunctionals also revealed gender role definitions less polarized in the masculine direction. Female patients did not reveal any additional decrements beyond those mentioned previously, and some equivocation in defining gender role. However, detailed analyses of Experience and Fantasy subtests depicted female patients as more creative and less constrained in their sexual activities. Conclusions suggest that sexually dysfunctional patients do maintain a characteristic psychological profile but one that is distinct for males and females.

Adult↗
PubMed1979

The invested partner in sexual disorders: a profile.

To determine the relevant psychosexual characteristics of invested partners of patients with sexual disorders, the authors administered the Derogatis Sexual Functioning Inventory (DSFI) to 51 invested partners and 200 normal volunteers. Female invested partners (N = 18) participated in a significantly more constricted range of specific sexual activities and revealed significantly lower sexual drive than the normal women. Tbey also had significantly lower scores on the femininity component of the gender role definition subtest. Male invested partners (N = 33) also showed significantly lower femininity scores and had somewhat lower scores on endorsement of specific sexual experiences. Degree of sexual satisfaction in the invested partners was comparable to that of their sexually dysfunctional partners.

Adult↗