Studies on polymers from cyclic dienes. VIII. Cationic polymerization of 1.3-[dimethylcyclopentadiene] and a general mechanism for cationic polymerizations of cyclopentadiene derivatives

Polymerization of 1.3-dimethylcyclopentadiene was carried out with FRIEDEL -CRAFTS and ZIEGLER -type catalysts. All polymers obtained were soluble. The polymers had 45 to 55% 1.4-structure and 55?45% 3.4-structure. The polymerization appears to go through a tertiary carbonium ion, in contrast to that of monosubstituted cyclopentadienes. In copolymerization of 1.3-dimethylcyclopentadiene (M₁) with cyclopentadiene (M₂), the former showed higher reactivity: r₁ = 6.85 ± 1.10, r₂ = 0.30 ± 0.10, at ?78°C. Comparison of the structures of polymers obtained by cationic polymerization of substituted cyclopentadienes revealed a general mechanism which explains the mode of the monomer addition.     

Identification of neural pathways involved in genital reflexes in the female: a combined anterograde and retrograde tracing study

The medial preoptic area (MPOA) is important for reproductive behavior in females. However, the descending pathways mediating these responses to the spinal motor output are unknown. The MPOA does not directly innervate the spinal cord. Therefore, pathways mediating MPOA-induced changes in sexual behavior must relay in the brain. The nucleus paragigantocellularis (nPGi) projects heavily to spinal circuits involved in female sexual reflexes and is involved in the tonic inhibition of genital reflexes. However, the periaqueductal gray (PAG) is also important for female sexual behavior. The present study examined the hypothesis that the MPOA output relays through PAG and the nPGi before descending to the spinal cord. We used anterograde and retrograde tracing techniques to examine the descending pathways and relay sites from the MPOA to the spinal cord and the nPGi in the female rat. Injection of biotinylated dextran amine into the MPOA produced dense labeling in specific regions of the PAG and Barrington's nucleus; anterogradely labeled fibers terminated close to neurons retrogradely labeled from the spinal cord in the PAG, Barrington's nucleus, nPGi, lateral hypothalamus and paraventricular nucleus (PVN). Anterogradely labeled fibers and varicosities were also found close to neurons retrogradely labeled from the nPGi in the PAG, lateral hypothalamus and PVN. These results suggest that the major MPOA output relays in the PAG and nPGi before descending to innervate spinal circuits regulating female genital reflexes and that the MPOA plays a multifaceted role in female reproductive behavior through its modulation of PAG output systems.     

Error behaviors associated with loss of competency in Alzheimer's disease

OBJECTIVE: To investigate qualitative behavioral changes associated with declining medical decision-making capacity (competency) in patients with AD. BACKGROUND: Qualitative measures can yield clinical information about functional changes in neurologic disease not available through quantitative measures. METHODS: Normal older controls (n = 21) and patients with mild and moderate probable AD (n = 72) were compared using a standardized competency measure and neuropsychological measures. A system of 16 qualitative error scores representing conceptual domains of language, executive dysfunction, affective dysfunction, and compensatory responses was used to analyze errors produced on the competency measure. Patterns of errors were examined across groups. Relationships between error behaviors and competency performance were determined, and neurocognitive correlates of specific error behaviors were identified. RESULTS: AD patients demonstrated more miscomprehension, factual confusion, intrusions, incoherent responses, nonresponsive answers, loss of task, and delegation than controls. Errors in the executive domain (loss of task, nonresponsive answer, and loss of detachment) were key predictors of declining competency performance by AD patients. Neuropsychological analyses in the AD group generally confirmed the conceptual domain assignments of the qualitative scores. CONCLUSIONS: Loss of task, nonresponsive answers, and loss of detachment were key behavioral changes associated with declining competency of AD patients and with neurocognitive measures of executive dysfunction. These findings support the growing linkage between executive dysfunction and competency loss.     

Executive dysfunction and loss of capacity to consent to medical treatment in patients with Alzheimer's disease

Loss of medical decision making capacity (competency) is an inevitable consequence of Alzheimer's disease (AD) and is an important subject for neuropsychological investigation. Consent capacity involves a complex set of comprehension, encoding, information processing, decision making, and communication abilities, which ultimately must have an explicit neurological basis. This article examines the role of executive dysfunction in loss of consent capacity in patients with AD. The authors first describe a cognitive neuropsychological model for understanding loss of consent capacity in AD. The article also reviews neuropsychological studies that have used a psychometric instrument to test consent capacity under different legal standards (Capacity to Consent to Treatment Instrument). These studies indicate that when multiple cognitive functions are associated with declining competency of AD patients on the Capacity to Consent to Treatment Instrument legal standards, measures of simple executive function are the predominant predictors. These empirical findings are discussed and related to the conceptual model. The findings support the growing body of literature linking frontal neural systems and executive cognitive functions to competency and to higher order functional capacities.     

Coexistence of benign phyllodes tumor and invasive ductal carcinoma in distinct breasts: case report

This report describes a rare case of coexistence of benign phyllodes tumor, which measured 9 cm in the right breast, and invasive ductal carcinoma of 6 cm in the left breast, synchronous and independent, in a 66-year-old patient. The patient underwent a bilateral mastectomy due to the size of both lesions. Such situations are rare and usually refer to the occurrence of ductal or lobular carcinoma in situ when associated with malignant phyllodes tumors, and more often in ipsilateral breast or intra-lesional.