Decline in striatal dopamine D1 and D2 receptor activation in aged F344 rats

Aging differentially affects receptor function. In the present electrophysiological study we compared neuronal responsiveness to locally applied dopamine D1 and D2 receptor agonist in the striatum of female Fischer 344 rats aged 3 and 26-27 months. In a subgroup of the old rats, the nigrostriatal dopamine bundle was destroyed unilaterally with 6-hydroxydopamine (6-OHDA) to assess receptor plasticity in response to denervation. Spontaneous firing rate of striatal neurons was higher in aged compared to young rats. Higher doses of the D1 agonist SKF 38393 or the D2 agonist quinpirole were required to elicit a 50% change in firing rate in aged compared to young rats. No difference with SKF 38393 or quinpirole was detected between 6-OHDA denervated and control (nonlesioned) striatum in aged rats. Supersensitivity to D2 agonists has been reported following 6-OHDA lesions in young rats. These observations suggest that D2 receptors in aged rat striatum might not be as plastic as in younger rats.     

A comparison of porosity, fabric and fractal dimension as predictors of the Young''s modulus of equine cancellous bone

Ependymomas are rare neuroectodermal tumors arising from ependymal cells of the ventricular system, choroid plexus, filum terminale, and central canal of the spinal cord (1,2). This review focuses on intracranial ependymomas with special emphasis on pathology, etiology, cytogenetic characteristics, and adjuvant radiation therapy. Recent advances in neurosurgical technique, radiation therapy, and molecular biology have affected management of these tumors and have the potential to increase long-term cure rates. The role of highly advanced radiation therapy techniques such as stereotactic radiosurgery will need to be better defined.     

Chromosome-specific aneusomy in carcinoma of the breast

Fluorescence in situ hybridization was performed on touch preparations from 55 primary infiltrating ductal carcinomas of the breast to determine numeric chromosome abnormalities. The frequency of aneusomy, measured by both nondisomy and chromosomal gain, was determined for chromosomes X, 4, 6-12, 17, and 18 with the use of chromosome-specific, alpha-satellite DNA probes. The presence of chromosome-specific numeric abnormalities was correlated with established clinicopathological parameters, including tumor size, lymph node involvement, tumor grade, estrogen receptor level, and menopause status. In addition, a case-control study was performed to explore a possible association between chromosome-specific aneusomy and recurrence in lymph-node-negative patients. Although chromosomes 8 and 6 were most frequently aneusomic, numeric abnormalities of chromosomes 4 and 11 were most strongly associated with established prognostic factors. For chromosomes 4 and 11, strong associations were found with tumor involvement of lymph nodes and increased tumor size, along with a weaker association with tumor grade. In addition, numeric abnormalities of the following chromosomes were associated with the corresponding prognostic factors: chromosomes X, 7, and 12 with lymph node status; chromosomes 10, 17, and 6 with tumor size; and chromosomes 7, 12, 17, and X with tumor grade. No correlations were observed with estrogen receptor level or menopause status. In the case-control study performed on isolated nuclei of paraffin-embedded tissue from lymph node-negative breast cancer patients (19 cases and 19 controls), the gain of chromosome 4 was correlated with disease progression. These findings suggest that chromosome-specific aneusomy is associated with certain established prognostic factors and may be associated with disease progression.     

Amylase: creatinine clearance ratio and urinary excretion of lysozyme in acute pancreatitis and acute duodenal perforation

The amylase:creatinine clearance ratio in patients suffering from acute pancreatitis or acute duodenal perforation was higher than normal in both groups of patients. These findings cast doubt on the value of this parameter as a specific index of acute pancreatitis. The mechanism or mechanisms underlying the increased amylase excretion have not been determined. However, the markedly elevated urinary excretion of lysozyme observed in some patients suggests, by analogy, that diminished tubular reabsorption of amylase may contribute towards the elevated amylase:creatinine ratio.     

Foreign serum-induced pancreatitis in mice. II. Secretory disturbances of acinar cells

As previously reported, pancreatic acinar cell necrosis and inflammation develop in mice a few hours after one intraperitoneal injection of foreign serum. However, sublethally injured acinar cells exhibited notable increases in both zymogen granule numbers and amylase activity, observed within 3 hours and increasing with time. These two changes were coupled with a progressive decrease in the secretory response to pilocarpine and were preceded by significant disturbances in pancreatic tissue concentrations of sodium and potassium. We conclude that (1) the granule increase results from an induced disturbance of the granule exocytosis mechanism while granule formation continues and, therefore, (2) the granule secretory process is more sensitive to the serum injury mechanism than is the zymogen synthesis process. Although the granule increases developed in acinar cells throughout most of the nonnecrotic gland and persisted for at least 24 hours, acinar cell necrosis was maximal in extent--approximately 25% of the gland in severest form--by 12 to 15 hours. We conclude, therefore, that the increase in granules is neither the primary determinant nor initiator of acinar cell death. The latter is likely caused by disturbed plasma membrane functions, sufficient in some cells to result in lethal changes in ion and fluid composition. The injury mechanism, which permits granule formation to go on in the face of impaired granule exocytosis, is yet to be worked out. The possibilities are discussed in relationship to the reactivity of foreign sera for target cell plasma membranes.     

Further characterization of the complementation group B temperature-sensitive mutant of respiratory syncytial virus

ts-2, a temperature-sensitive and plaque morphology mutant of respiratory syncytial virus and sole representative of complementation group B, was compared with members of the other complementation groups of respiratory syncytial virus (group A [ts-1] and group C [ts-7]). ts-2 was found to be 10- to 1,000-fold more restricted in growth and ability to spread at restrictive temperatures (37, 38, and 39 degrees C) than at the permissive temperature (32 degrees C). In temperature shift-up experiments, the ts defect of ts-1 and other members of complementation group A was found to effect a late function that was required for at least 13 h in the replicative cycle. The ts lesion of ts-7 affected a function early in the replication cycle. In contrast, ts-2 was not temperature sensitive when studied by the shift-up technique. The discrepancy between the ts plaque property and failure to detect temperature sensitivity during the shift-up experiment was resolved when it was shown that ts-2 had a defect in adsorption or penetration or both at the restrictive temperature. Clonal analysis of revertant ts-2 showed a coordinate restoration of ts+ phenotype ans syncytium-forming capacity. It appears that ts-2 has a defect in a protein that is involved in adsorption and/or penetration of virus and is also responsible for cell fusion activity.     

Nickel sulphide-induced rhabdomyosarcomata in rats

Fifty-nine Fischer rat tumors and eleven Hooded rat tumors induced by intramuscular injection of Ni3S2 were examined and their histopathologic and cytologic characteristics studied. Nine out of eleven Hooded rat tumors metastasized whereas 15 out of 59 Fischer rat tumors metastasized within 30 days. Histopathological characterization of the Ni3S2-induced tumors was made according to their preponderant cellular constitution. They were grouped into six types: well-differentiated rhabdomyosarcomas, poorly-differentiated rhabdomyosarcomas, embryonal rhabdomyosarcomas, mesenchymal tumors, leiomyosarcoma-like tumors and fibrosarcoma-like tumors. Forty-seven of total of 70 were rhabdomyosarcomas. Tumors with shorter latent periods in Fischer rats and tumors with fleshy and soft texture demonstrated a higher incidence of metastases.     

The effects of anemia on heme synthesis parameters during lead exposure

The effects of anemia during lead exposures were studied using an infant baboon animal model. When the hemoglobin concentration was reduced to less than 70% of normal, a marked blood lead increase was observed and the free erythrocyte porphyrin value, aminolevulinic acid dehydratase activity and reticulocyte counts increased. Special emphasis should be placed on nutritional effects in lead exposures.