Motor and non-motor sequence learning in children and adolescents with cerebellar damage.

Cerebellar involvement in motor and non-motor sequence learning was examined with serial reaction time tasks (SRT). Our sample consisted of 8 children and adolescents who had undergone surgical removal of a benign posterior fossa tumor (PFT) during childhood. None of them had undergone chemotherapy or cranial radiation therapy (CRT). Ages ranged from 1-11 years at surgery and 9-17 years at testing. The children were tested not earlier than 2.5 years after surgery (M = 5.9 years), enabling brain plasticity and recovery of functions. Their performance was compared with a matched control sample. The PFT group was not impaired in the implicit learning of sequences, as reflected in their performance in blocks with a repeated sequence, both before and after a random block. However, in the perceptual task, their performance deteriorated more than that of the control group when a random block was introduced, suggesting that it was more difficult for the patients to respond flexibly or change their response set when encountering changing task demands. These results are in line with another study by our group on task switching with the same patients.     

Early bladder outlet obstruction in fetal lambs induces renal dysplasia and the prune-belly syndrome

A model of posterior urethral valves in fetal lambs was developed in order to evaluate the effect of intrauterine urinary obstruction on the developing kidney. Complete urethral obstruction was induced in five fetal lambs at 43 to 45 days of gestation. Two control fetal lambs underwent sham operations. At full term (140 days), two of the five experimental lambs and both control lambs were available for postmortem examination. Results of gross and histological examination of the control lambs were normal. In contrast, the kidneys of the experimental lambs were markedly asymmetrical in size. Histological examination of the kidneys in experimental lambs showed cystic dilatation of the collecting ducts and occasional cystic dilatation of Bowman's spaces, features compatible with obstruction. Also noted were peripheral cortical cysts and primitive tubules lined with cuboidal epithelium and surrounded by fibromuscular collarettes, characteristic of renal dysplasia. One of the infant lambs had many characteristics of the prune-belly syndrome, including a wrinkled, markedly distended abdomen, deficient abdominal wall musculature, flared chest wall, limb deformities, and undescended testes. These results suggest that early in utero urethral obstruction (at the beginning of the second third of gestation) causes renal dysplasia. The results also support the hypothesis that the prune-belly syndrome results from abdominal distention that occurs early in gestation.     

Chromogenic Detection of Aminoglycoside Phosphotransferases

A coupled chromogenic reaction (based on an agar overlay combining NADH, pyruvate kinase, lactate dehydrogenase, phosphoenolpyruvate, ATP, and kanamycin sulfate with thiazolyl blue-phenazine methosulfate for detection of NADH consumption) was optimized for the detection of aminoglycoside phosphotransferases (APHs). When used after analytical isoelectrofocusing of bacterial extracts from APH-producing strains, this method revealed one band in each of two strains with a genetically confirmed APH (3′) I and two bands in another strain with both APH (3′) I and APH (3′) VI, whereas no bands were detected in susceptible control strains or in aminoglycoside-resistant microorganisms without APH genes.     

Carcinoma of the prostate with atypical immunohistological features. Clinical and histologic correlates

In seven patients with undifferentiated carcinoma of the prostate, the immunohistochemical stain for prostate-specific antigen was negative. The stain for prostatic acid phosphatase done on the same tissue samples was diffusely positive in three, focally positive in three, and negative in one. Only the three with diffusely positive immunostaining had elevated serum acid phosphatase levels, although five had evidence of metastatic disease. All seven neoplasms were histologically similar, being composed of large cells with large nuclei, a moderate amount of cytoplasm, and indistinct cell borders. All tumors grew as broad sheets within the prostatic stroma as well as in the prostatic urethra; in six cases. Thus, prostatic carcinoma with this histologic pattern frequently loses prostate-specific antigen immunoreactivity. Awareness of this occurrence should prevent a misdiagnosis of urothelial carcinoma in such cases. The prostatic origin of these neoplasms can usually be verified by prostatic acid phosphatase immunostaining, which proves to be more sensitive in this particular setting.