Excitation of antidromically identified neurosecretory cells of the paraventricular nucleus by oxytocin applied iontophoretically

Oxytocin was applied iontophoretically to the cell membrane of neurons in the paraventricular (PV) and supraoptic (SO) nuclei of the hypothalamus. Oxytocin excited the majority of PV units which could be activated antidromically by stimulation of the neural lobe but failed to excite PV neurons which could not be identified in this way and cells in the SO nucleus, cortex, and thalamus. Vasopressin had no excitatory effects either on the PV nucleus or the SO nucleus. Intravenous injections of oxytocin did not affect the firing rates of PV nucleus units, so it is hard to find a physiological meaning for these observations. However, the need to prevent such excitation may go some way to explain the elaborate neurophysin-packaging system associated with oxytocin synthesis and transport.     

Comparison of the aerodynamic size distribution of chain-like aggregates measured with a cascade impactor and a spiral centrifuge.

Several authors have suggested that chain-like aggregates fragment in the jets of cascade impactors and that the impactor consequently underestimates the median aerodynamic diameter and overestimates the geometric standard deviation (GSD). The aerodynamic size distribution of (Pu0.14U0.86)02.2 aggregates were measured simultaneously with two Mercer cascade impactors and a LAPS spiral centrifuge to investigate this problem. Although the median aerodynamic diameters were generally in good agreement, the impactor consistently measured higher values for the GSD than did the spiral centrifuge. Based on experiments in which losses in the centrifuge inlet were measured, it was concluded that the centrifuge had measured the aerodynamic size distribution more accurately than the impactor. Interception of chain-like aggregates on the first few impactor stages may have been the primary reason for the disparity between the impactor and centrifuge measurements.     

Pathologic axons and synapses in human neuropsychiatric disorders.

Ultrastructural studies of cerebral biopsy specimens from patients with various forms of psychomotor retardation and dementia have disclosed pathologic changes in axons and presynaptic or postsynaptic processes. The clinical disorders with lesions in axons and presynaptic terminals are reviewed. Three basic abnormalities have been detected: proliferation of tubulovesicular structures which probably originate from the smooth endoplasmic reticulum, "abnormal" mitochondria, and proliferation of 80 to 100 A filaments. Understanding of the pathogenesis of human disorders associated with axonic or "synaptic" lesions will probably depend on progress in areas of basic biomedical research concerned with the synthesis and turnover of biological membranes and the packaging and secretion of neurotransmitters, elucidation of mechanisms of cytoplasmic streaming and axoplasmic flow, and biophysical and biochemical characteristics and functions of "fibrous" proteins (neurotubules, neurofilaments, pathologic fibrous proteins). In several cases of mental retardation of unknown etiology, abnormal dendritic spines of cortical neurons have been observed with the use of the Golgi method. These dendritic (postsynaptic) disorders have been attributed to defective development ("dysgenesis"). The knowledge provided by ultrastructural analysis of brain tissue from the human disorders of mental retardation or dementia is "still formless, incomplete, lacking the essential threads of connection," and only future developments in lacking neurobiology will make possible the dissection of the primary phenomena from the secretory and probably irrelevant findings.     

Measuring antenatal depression and anxiety: findings from a community-based study of women in Hyderabad, Pakistan

This study evaluated the psychometric properties of two possible measures of depression and anxiety among pregnant women in Pakistan for use in the Global Network for Women's and Children's Health Research project, a collaborative, international multi-site research network investigating methods for improving pregnancy and birth outcomes in developing countries. The first measure, the Aga Khan University Anxiety and Depression Scale (AKUADS), is an Urdu language scale originally developed for the general Pakistani population, whereas the second measure, the How I Feel scale, was designed for pregnant women in the United States. In an earlier pilot study, we found that the two scales demonstrated similar levels of diagnostic validity. Because neither scale was designed for the specific population of interest, item response theory analyses were conducted to evaluate the psychometric properties of the scales at three levels of measurement: scale, item, and response option. The study results provide insights that may be useful to researchers or clinicians developing or using scales in this population. In particular, our findings suggest that scales designed for populations with lower literacy, such as our target population, may improve data quality by including no more than three response options (e.g., almost always, sometimes, and never) and keeping the direction of item wording consistent throughout the scale. Based on the results from the current study, we recommend a short form of the AKUADS which removes poorly functioning items and reduces respondent burden while retaining the reliability and validity of the longer form.