Effects of dopaminergic drugs on delayed reward as a measure of impulsive behavior in rats

RATIONALE

Impulsive individuals exhibit an exaggerated preference for immediate rewards over delayed but larger rewards, perhaps because they value the delayed rewards less. Dopamine (DA) has been postulated to mediate the incentive value of rewards, thus it may also mediate the exaggerated preference for immediate rewards in impulsive individuals. In this paper, we investigate the effects of DA agonists and antagonists on the value of delayed versus immediate rewards.

OBJECTIVES

The study had three main objectives: (1) to determine the effects of D1 and D2 type DA antagonists on the value of delayed rewards, (2) to determine the effect of the indirect DA agonist d-amphetamine on the value of delayed rewards, (3) to determine the sensitivity of the adjusting amount (AdjAmt) procedure to acute one-day changes in delay to reward, amount of reward, deprivation level and starting amount.

METHODS

In the AdjAmt procedure, rats choose between an adjusting amount of water given immediately (adjusting alternative) and a constant 150 microliters water delayed by 4 s (standard alternative). The immediate amount of water is adjusted across trials until the rat chooses both alternatives with equal frequency (indifference point). The final adjusted amount is an indicator of the subjective value of the standard alternative.

RESULTS

The D1/D2 antagonist flupenthixol (25, 50, and 100 micrograms/kg) and the D2 antagonist raclopride (40, 80, and 120 micrograms/kg), decreased the indifference points, whereas the D1 antagonist SCH 23390 (5, 10, and 20 micrograms/kg) did not affect the indifference point. All three DA antagonists slowed responding. The indirect DA agonist amphetamine (0.5, and 1.0 mg/kg) had effects opposite to those of the DA antagonists, it decreased choice latency, increased the number of trials completed and increased the indifference point. Decreasing the water deprivation level (6, 24, and 48 h) had no effect on the indifference points but slowed responding. Increasing the delay to reward (2, 4, and 8 s) and decreasing the amount of water available for choosing the standard alternative (300, 150, 75 microliters) decreased the indifference point.

CONCLUSIONS

The results indicate that amphetamine increased the value of delayed rewards (decreased impulsivity) and that D2 but not D1 receptor antagonists decreased the value of delayed rewards (increased impulsivity). The procedure was sensitive to acute 1-day changes in delay and magnitude of reward.

Subacute cutaneous lupus erythematosus in Iceland

Identification of patients with subacute cutaneous lupus erythematosus (SCLE) in Iceland was performed by means of a survey based on the histopathologic or immunofluorescent diagnosis of lupus erythematosus. Respondents underwent serologic studies, gave histories, and, dependent upon the latter, were examined. The resultant proportional rate of patients with SCLE approached 10% of all lupus erythematosus cases.

Oral acanthosis nigricans: report of a case and comparison of oral and cutaneous pathology

Malignant acanthosis nigricans is usually associated with adenocarcinomas of the digestive tract. The lesions of acanthosis nigricans commonly run a parallel course to the associated malignancy, producing hyperpigmented, roughened plaques on the skin and, sometimes, verruca-like papules on the oral mucosa. The clinical differences between cutaneous and oral acanthosis nigricans are mirrored by the marked differences in the histopathology. Because oral acanthosis nigricans is uncommon, recognizing histologic features may be difficult. The oral lesions have a true acanthosis and epithelial papillary hyperplasia while the cutaneous forms show slight irregular acanthosis that alternates with areas of epidermal atrophy and dermal papillomatosis.

The histology of malignant melanoma

A brief review of the histology of malignant melanoma is presented, including various prognostic indicators of the biologic behavior of this neoplasm. Reproducible criteria are outlined in an attempt to provide for a more accurate diagnosis and subsequent treatment of this life-threatening disease.

The effects of resin of podophyllin on condyloma acuminatum

The effects of resin of podophyllin on lesions of condyloma acuminatum have posed problems to pathologists who sought to differentiate them histologically from squamous cell carcinoma in situ. The most striking histologic changes in lesions of condyloma acuminatum following application of resin of podophyllin occur within the first 48 hours. They are pallor of the epidermis secondary to both intracellular and intercellular edema, numerous necrotic keratinocytes in the lower half of the epidermis, and a marked increase in the number of mitotic figures there. Within the edematous papillary dermis, there is a scattered infiltrate of lymphocytes, histiocytes, and neutrophils. The absence of nuclear atypia, multinucleated keratinocytes, and dyskeratotic cells, and the presence of the orderly sequence of maturation of keratinocytes within the epidermis permit histologic differentiation of podophyllin-treated condyloma acuminatum from true squamous-cell carcinoma in situ. The acute histologic changes induced by podophyllin begin to wane by 72 hours after the resin has been applied. At this time, necrotic keratinocytes are found mostly within the upper portion of the epidermis and few mitotic figures are seen. By 1 week after application of podophyllin there are virtually no histologic abnormalities within the epidermis.

Restoration of Trichophyton mentagrophytes growth in medium depleted of metals by chelation: importance of iron

The present study examined the requirement of Trichophyton mentagrophytes ATCC-18748 for iron. Nutrient broth depleted of iron by the chelating cation exchange resin Chelex-100 did not support the growth of T. mentagrophytes beyond germ tube formation. The soluble chelate of iron, ferric ammonium citrate, restored the capacity of the chelated medium to support fungal growth in proportion to the amount of iron added. Ferric chloride, which rapidly becomes insoluble at neutral pH, was not effective in the medium. The soluble salts of cobalt, chromium, copper, manganese, nickel, and zinc individually did not replace the requirement for iron. A method for defining the iron requirement based upon utilization of iron from ferric ammonium citrate is described. These data indicate that the growth of T. mentagrophytes ATCC-18748 is iron-dependent, which is consistent with the hypothesis that serum transferrin inhibits dermatophyte growth by the mechanism of iron deprivation.

Cornoid lamellation. A histologic reaction pattern

Cornoid lamellation is a constant histologic marker of porokeratosis in its many variants. This histologic appearance, heretofore thought to be pathognomonic of and restricted to porokeratosis alone, has also been found by us in a variety of other conditions. Cornoid lamellation is, therefore, analogous to the histologic findings of focal acantholytic dyskeratosis, epidermolytic hyperkeratosis, and follicular mucinosis as a distinctive histologic reaction pattern that reflects disordered progression of epidermal cells to cornification.

Cowden's disease

Cowden's disease, a rare genodermatosis, is associated with characteristic cutaneous and oral lesions: papillomas, verrucous papules, and acral keratoses. Various internal anomalies involving the breast, thyroid, and gastrointestinal, reproductive, and skeletal systems are also seen in patients with this syndrome complex. Twelve of the thirty-two reported patients have been subject to cancers, most commonly of the breast. The characteristic skin and oral lesions make possible an early diagnosis of this disease and permit close follow-up of these patients for the development of any internal disease.

Chondrodermatitis nodularis chronica helicis. A review with emphasis on steroid therapy

Chondrodermatitis nodularis chronica helicis, a disease involving the ear helix of middle-aged to elderly persons is described herein. The clinical, histologic, and therapeutic aspects of this entity are discussed with special emphasis on treatment with intralesional steroids. Several etiologic and pathogenetic mechanisms are also mentioned.

Intravenous miconazole therapy of mycotic infections

The efficacy and safety of intravenously administered miconazole nitrate was examined in eight patients with the following infections: cutaneous North American blastomycosis (one), extensive dermatophytosis(one), and chronic mucocutaneous candidiasis (six). Mycologic assessment included direct examination for fungal elements, fungal culture, and histopathology. Laboratory evaluations were performed before and at regular intervals during the study. The total miconazole nitrate dosage, which was administered over a seven- to 32-day period, ranged from 4.0 to 46.8 g. Follow-up examinations extended from two to 15 months. Excellent results were obtained in five patients and fair results in three. No renal, cardiac, hepatic, or hematopoietic toxicity was observed. Other side effects, however, necessitated premature cessation of therapy in four patients. Overall, intravenously administered miconazole is an effective antifungal agent for these cutaneous infections.

Irritant and allergic reactions to topically applied Micatin cream

Miconazole nitrate (Micatin cream) is a potent antifungal agent. Few side effects have been reported with topical application. We report on 10 patients who exhibited an intolerance to topical use of this drug. Most of the reactions were irritant in nature but in two instances, an allergic contact dermatitis was observed. Patch tests were positive to the cream base.

Pruritic urticarial papules and plaques of pregnancy

We report an intensely pruritic cutaneous eruption that occurs in the third trimester of pregnancy. The clinical manifestations include erythematous urticarial papules and plaques that begin on the abdomen and spread to involve the thighs and occasionally the buttocks and arms. This dermatosis appears to be clinically distinct from previously described pruritic eruptions occurring in pregnancy. Biopsy specimens of the lesions show two histological patterns. We propose that this entity be termed "pruritic urticarial papules and plaques of pregnancy (PUPPP)".

Bowenoid papulosis of the genitalia

We report 34 cases of bowenoid papulosis of the genitalia. In each case, the patient had numerous reddish brown or violaceous papular lesions, some distinctly verrucoid, situated on the genitalia. Although clinically the lesions invariably appeared benign, histologic examination of specimens from the genital lesions in each patient showed changes of squamous cell carcinoma in situ. Many of the patients gave a history of preceding viral lesions on the genitalia. Therapy in all cases was conservative but thoroughly ablative. We view bowenoid papulosis as a new entity whose biologic behavior if untreated is as yet unknown.

Bowenoid papulosis of the penis

During the past 18 months we have studied 36 biopsy specimens taken from 11 young men ranging in age from 21 to 36, each of whom had multiple, reddish to violaceous papules, some distinctly verrucoid or velvety on either or both the shaft and glans of the penis. The clinical diagnoses accompanying the biopsy specimens were lichen planus, psoriasis and condyloma acuminatum. In no instance was carcinomia in situ suggested in the differential diagnosis. Histologically, however, all specimens submitted showed indubitable changes of squamous cell carcinoma in situ.

Skin changes and diseases associated with pregnancy

During the gestational period, the skin is among the many organs undergoing changes. Various endocrine changes occurring in pregnancy are thought to give rise to certain skin changes such as pigmentary alterations, abnormalities in hair growth, vascular anomalies, and striae. Also, there are several skin diseases unique to the pregnant woman. Whereas the physiologic skin changes are mainly of cosmetic importance, the various pregnancy-unique skin diseases have associated symptoms, and an increase in both fetal and/or maternal morbidity and mortality is associated with several of these skin diseases.

Cowden's disease: a case report and review of the literature

Cowden's disease is one of the rare genodermatoses. The most characteristic findings in this disease are cutaneous and oral lesions that are widespread papillomas and verrucous papules. On the palms the lesions are keratoses. Aside from these findings, this syndrome complex is sooner or later associated with various internal abnormalities involving the mammary, thyroid, gastrointestinal, reproductive and skeletal systems. In the 28 reported cases, 13 cancers have been found, most of the breasts. Because of the characteristic cutaneous and oral lesions, it is possible to recognize this disease early and then to follow afflicted patients closely for the possibility of development of cancers or other abnormalities of other organs.