[Plasmocytoma of the ureter--a rare cause of hydronephrosis: case report and review of the literature]. / Plasmozytom des Harnleiters--seltene Ursache einer Harnstauung: Fallbericht und Literaturübersicht.

INTRODUCTION: Plasmocytoma is an aggressive B-cell lymphoma with diffuse and multi-located-infiltration of the bone marrow. There are only a few cases in the literature reporting an extraosseous manifestation of plasmocytoma, e. g., in the urinary tract. CASE REPORT: We report on an 80-year-old female patient with known plasmocytoma presenting with renal colics. Ultrasonography demonstrated marked hydronephrosis and retrograde pyelography disclosed a short and filiform stenosis of the ureter. Surgical exploration revealed an infiltration of the distal ureter by the known plasmocytoma. The affected ureter segment could be removed completely and ureterocystoneostomy was performed successfully. CONCLUSIONS: To the best of our knowledge, we present the first case of an isolated plasmocytoma of the ureter. Although extremely rare, it should be considered as a differential diagnosis of circumscribed ureteral strictures.

Radiochemotherapy after transurethral resection is an effective treatment method in T1G3 bladder cancer.

AIM: Conservative therapy using deep transurethral resection (TUR) followed by radiochemotherapy is a novel treatment strategy in stage TI grade 3 (TIG3) transitional cell carcinoma (TCC) of the bladder. The aim of this study was to present our long-term results of radiochemotherapy in T1G3 TCC patients. MATERIALS AND METHODS: A total of 64 patients with TIG3 TCC of the bladder underwent a TUR and a subsequent radiochemotherapy protocol at our institution. Following TUR, a median dose of 55.8 (range; 45-69.4) Gy radiation therapy was applied to the bladder, and simultaneous chemotherapy was initiated using cisplatin, carboplatin and/or 5-fluorouracil. After completion of the protocol, response was evaluated by repeat TUR, and check cystoscopies were performed at regular intervals. Median patient age was 66 (range; 30-82) years and median follow-up was 43.2 (range; 6-127) months. RESULTS: Complete response was achieved in 55 (90.2%) patients. Of the complete responders, 7 patients experienced a superficial (Ta, T1) recurrence and 8 patients had progression. In 8 patients with refractory superficial and invasive relapses, a salvage cystectomy was mandated. The overall progression rate was 14%. The overall and disease-free survival rates were 76% and 93%, respectively at 5 years. During followup, 4 patients suffered from reduced bladder capacity, and 2 patients underwent cystectomy due to shrinking bladder. CONCLUSION: Combined multimodality therapy is a safe and curative treatment option for patients with T1G3 TCC of the bladder in the hands of dedicated multimodality teams. Therefore, it is reasonable to justify radiochemotherapy combined with TUR in the first-line treatment of T1G3 tumors.

Tolerance of half-body irradiation as systemic therapy for patients with locally advanced breast cancer.

BACKGROUND: Locally advanced breast cancer (LABC) is one of the main causes of cancer death among women in Bulgaria. In 1988, when this study started, there was still controversy about the role of chemotherapy in controlling systemic disease. There were encouraging results from the Radiation Therapy Oncology Group (RTOG) 82-06 study suggesting that half-body irradiation (HBI) should be used earlier in the disease course to prevent the development of metastases. There were many patients with LABC requiring treatment, but there was a problem with obtaining the drugs needed; they were expensive and not consistently available. PROCEDURE: Taking into account the medical contraindications to chemo-therapy treatment, its toxicity, and the possibility of chemoresistance, we initiated this study to look at the effects of HBI given as two fractions of 4 Gy to the upper and then lower parts of the body, after surgery and before local radiotherapy. RESULTS: The acute tolerance of this regimen in 36 patients with LABC was as good as it was in 4 additional LABC patients with M1 disease, and hematologic recovery was satisfactory. CONCLUSIONS: We conclude that systemic treatment with HBI is tolerable. It therefore may be a convenient and cost-effective treatment for LABC, although better treatments are still needed.

Momentary maximizing in concurrent schedules with a minimum interchangeover interval.

Eight pigeons were trained on concurrent variable-interval variable-interval schedules with a minimum interchangeover time programmed as a consequence of changeovers. In Experiment 1 the reinforcement schedules remained constant while the minimum interchangeover time varied from 0 to 200 s. Relative response rates and relative time deviated from relative reinforcement rates toward indifference with long minimum interchangeover times. In Experiment 2 different reinforcement ratios were scheduled in successive experimental conditions with the minimum interchangeover time constant at 0, 2, 10, or 120 s. The exponent of the generalized matching equation was close to 1.0 when the minimum interchangeover time was 0 s (the typical procedure for concurrent schedules without a changeover delay) and decreased as that duration was increased. The data support the momentary maximizing theory and contradict molar maximizing theories and the melioration theory.

Stimulus effects on concurrent performance in transition.

Six experimentally naive pigeons were exposed to concurrent variable-interval variable-interval schedules in a three-key procedure in which food reinforcement followed pecks on the side keys and pecks on the center key served as changeover responses. In Phase 1, 3 birds were exposed to 20 combinations of five variable-interval values, with each variable-interval value consistently associated with a different color on the side keys. Another 3 pigeons were exposed to the same 20 conditions, but with a more standard procedure that used a nondifferential discriminative stimulus on the two side keys throughout all conditions. In Phase 2, the differential and nondifferential stimulus conditions were reversed for each pigeon. Each condition lasted for one 5-hr session and one subsequent 1-hr session. In the last 14 conditions of each phase, the presence of differential discriminative stimuli decreased the time necessary for differential responding to develop and increased the sensitivity of behavior to reinforcement distribution in the 1st hr of training; during the last hours of training in each condition, however, the effects of the differential discriminative stimuli could not be distinguished from the effects of reinforcement distribution per se. These results show the importance of studying transitions in behavior as well as final performance. They may also be relevant to discrepancies in the results of previous experiments that have used nonhuman and human subjects.

Shock intensity and signaled avoidance responding.

Five rats were submitted to a signaled free-operant avoidance contingency. Throughout the experiment, shock intensity was varied from 0.1 to 8.0 mA, with shock duration constant at 200 milleseconds. Results indicate: (a) an all-or-none effect of shock intensity on response and shock rates, on percentage of shocks avoided, and on frequency of occurrence of responding during the preshock stimulus; and (b) no systematic effect of shock intensity on stimulus control, measured either by the percentage of stimulus presentations accompanied by a response or by the percentage of responses that occurred during those preshock stimuli. Such results indicate that for each subject there is a minimum shock intensity necessary to establish and maintain avoidance responding; intensities higher than this minimum value have little or no effect on responding (with an upper limit for those strong intensities with a general disruptive effect on behavior).

Frequency versus magnitude of reinforcement: New data with a different procedure.

Two pigeons, with previous exposure to concurrent schedules, were submitted to 29 sessions of 8 hours each with concurrent variable-interval variable-interval schedules in which reinforcement parameters changed from session to session. In the first nine sessions reinforcement durations were equal in both schedules while reinforcement frequencies varied; in Sessions 10 through 18, both frequency and duration of reinforcement were varied; in Sessions 19 through 29, only reinforcement duration was varied. Results with this different procedure confirm previous findings that behavior is more sensitive to changes in reinforcement frequency than to reinforcement magnitude.

Choice, experience, and the generalized matching law.

Five pigeons were exposed to different pairs of concurrent variable-interval, variable-interval schedules on nine experimental conditions of 30 sessions each. For every session, the parameters of the generalized matching equation were computed for the first five, six, seven, eight, and nine experimental conditions. The exponent a, both for response and time distribution, tended to decrease with increases in number of experimental conditions and to increase with number of sessions per condition, but values of k (bias) varied unsystematically. When the subjects were exposed to five new pairs of schedules, with 55 sessions per condition, the findings were confirmed. Data from the literature on the generalized matching law suggest that the variability of exponent values may be explained in part by the use of naive or experienced subjects in different investigations and by the variability in number of experimental conditions and in number of sessions per condition.

Behavior analysis and experimental pharmacology.

This paper provides an introduction to the field of behavioral pharmacology. A brief description of the main characteristics of behavior analysis is followed by a review of the contributions of experimental pharmacology to behavior analysis and vice versa. Finally, a section on new procedures in behavioral pharmacology outlines experimental situations in which complex kinds of behavior can to studied. These include: (a) temporal discrimination; (b) preference to be free and informed; (c) commitment, choice and self-control; and (d) high-order concept formation.

Concurrent avoidance of shocks by pigeons pecking a key.

Three pigeons were studied on concurrent, unsignaled, avoidance schedules in a two-key procedure. Shock-shock intervals were two seconds in both schedules. The response-shock interval on one key was always 22 seconds, while the response-shock interval associated with the other key was varied from 7 to 52 seconds in different experimental conditions. Response rates on the key associated with the varied schedule tended to decrease when the response-shock interval length was increased. Responding on the key associated with the constant schedule was not systematically affected.

Effect of experimentally induced chronic renal failure upon the behavior of rats.

Two groups of rats were submitted to a 2-hour training session under a free operant avoidance of shock contingency 23 weeks after surgery, which provoked a state of chronic renal failure (experimental group) or after a sham operation (control group). Subjects in the control group had superior performances than those from the experimental group when total of shocks received and total numbers of avoidance and escape responses were compared. Results of biochemical blood analyses obtained from samples taken immediately after the avoidance training session indicate that the experimental group showed higher plasma urea concentration, higher levels of creatinine and osmolarity. The data show that the procedure used to provoke chronic renal failure was successful, and results in general confirm and extend findings relative to the effects of acute renal failure on behavior.

Signalled free-operant avoidance of shock by pigeons pecking a key.

Two pigeons were trained to peck a key under a free-operant avoidance schedule. Then, changes in key color signalled the beginning (safe period) and the end (warning period) of the response-shock interval, with a response required to change the key color. Finally, a change in key color signalled the warning period and either a response or a shock reinstated the safe stimulus. During signalled avoidance, response rate was higher during the warning stimulus than during the safe stimulus. More responding tended to occur in the warning stimulus when it was terminated by either a response or a shock than by only a response. In either procedure, response latency during the warning stimulus was a function of the duration of the warning stimulus. In general, response and shock rate were higher during unsignalled than during signalled avoidance. When the warning stimulus was brief, the results were similar to those of unsignalled avoidance. These results confirm previous findings with pigeons, are in general agreement with data provided by other species in studies of signalled avoidance, and thereby indicate the transituationality of the key-pecking operant.

Key pecking as a function of response-shock and shock-shock intervals in unsignalled avoidance.

Five pigeons were exposed to an unsignalled avoidance procedure where key pecks were maintained through shock postponement. Functions obtained showed an inverse relationship between rate of responding and length of the response-shock interval, while changes in the shock-shock interval had no systematic effect on response rates. The rate of shocks delivered generally decreased with increases in length of both response-shock and shock-shock intervals. Results show that key pecking in pigeons, maintained through an unsignalled avoidance procedure, was affected by changes in response-shock and shock-shock intervals in the same manner as other responses in pigeons and in rats.

Interaction of frequency and magnitude of reinforcement on concurrent performances.

Frequency and magnitude of reinforcement were varied in concurrent variable-interval variable-interval schedules of reinforcement. The relative response rate to the two stimuli did not support the notion that choice approximately matches relative total access to food (the product of frequency and magnitude of reinforcement in one schedule divided by the sum of products of frequency and magnitude in both schedules). Relative response rates matched relative reinforcement value when that measure was adjusted to give more emphasis to reinforcement frequency than to reinforcement duration.