A protective role for testosterone in adjuvant-induced arthritis

We have investigated the role of the gonadal steroids testosterone (T) and progesterone in modulating: (1) the onset and severity of adjuvant-induced arthritis (AA), (2) the response of the hypothalamo-pituitary-adrenal (HPA) axis, and (3) the levels of plasma prolactin and anterior pituitary prolactin messenger ribonucleic acid (mRNA) in the rat. Male rats were castrated (CSX) and received either no T, low T or high T delivered using silastic implants. In a second study experimental groups comprised CSX/AA, CSX/AA + progesterone or CSX/AA + progesterone + T. The time of onset was sooner and the severity of AA was greater in CSX rats. Inflammation was prevented by T replacement. Endogenous plasma T levels were decreased in AA rats. In control animals with AA there was an increase in pro-opiomelanocortin (POMC) mRNA in the anterior pituitary and of plasma corticosterone, and a decrease in corticotrophin-releasing factor (CRF) mRNA. These changes in the HPA axis of AA and CSX/AA rats were reversed by T replacement. These data suggest that T has an important protective effect on the progress and severity of AA. This was reflected by a reversal of the neuroendocrine changes of the HPA axis. Progesterone treatment alone had no effect on the severity of the disease. Prolactin mRNA in the anterior pituitary was decreased in the CSX and in the CSX/AA group but was not altered by AA. Plasma prolactin was raised in AA but T replacement did not reduce these elevated levels despite the absence of disease. Thus, prolactin provides a poor indicator of inflammation, suggesting that it may not be a potent pro-inflammatory compound in AA.     

Arousal, numbing, and intrusion: symptom structure of PTSD following assault

OBJECTIVE: This study investigated hypotheses concerning the importance of symptoms of numbing in posttraumatic stress disorder (PTSD). METHODS: Symptoms of PTSD were assessed in 72 female rape victims and 86 female victims of nonsexual assault approximately 3 months after the crimes occurred. A principal-components factor analysis of subjects' symptoms was then undertaken. RESULTS: The analysis yielded three factors: arousal/avoidance, numbing, and intrusion. These were somewhat different from the symptom clusters in DSM-III-R, since effortful avoidance and numbing symptoms did not load on the same factor. Numbing symptoms appeared to be particularly important in identifying individuals with PTSD. CONCLUSIONS: The results imply that there are two patterns of posttrauma symptoms, one characterizing PTSD and the second characterizing a phobic reaction.     

Oxidation of low density lipoprotein by iron or copper at acidic pH

Oxidized low density lipoprotein (LDL) may play a significant role in atherosclerosis. We have investigated the effect of pH on the oxidation of LDL by iron or copper. When LDL was oxidized by iron in the presence of cysteine in either Hanks' balanced salt solution (HBSS) or Ham's F-10 medium, an acidic pH greatly decreased the lag period and increased the rate of formation of hydroperoxides and thiobarbituric acid-reactive substances (TBARS), and increased its uptake by macrophages. There was a dose-dependent increase of LDL oxidation at acidic pH in the presence of increasing concentrations of cysteine. When LDL was oxidized by copper in HBSS, an acidic pH increased the lag phase before the rapid formation of conjugated dienes, hydroperoxides, and TBARS, but increased its uptake by macrophages. Similar results were obtained using Ham's F-10 medium. Cysteine (100 microM) inhibited the modification of LDL by copper in HBSS at both pH 7.4 and 5.5 As atherosclerotic lesions may be acidic, these observations may help to explain why LDL oxidation occurs locally at these sites.     

Criteria for accurate usage of block models

The results of block model calculations for multiple discretizations of a dielectric sphere and circular cylinder suggest that it is essential that the cells must be arranged for a best-fit of the body being modeled, the matrix elements must be reasonably accurate, and the cells must be small enough so that the pulse-function basis approximation is not blatantly unreasonable. When these criteria are approximately satisfied the remaining errors appear to be mainly due to imperfect representation of the shape of the object being modeled. It appears that the accuracy can be improved by using discretizations having cells of reduced size near the surface of the object. Geometric factors are defined which allow testing the potential accuracy of a solution without dimensioning or inverting a large matrix. Several unique procedures for discretization are also described that have the potential of partially mitigating the errors due to inaccurate representation of the shape of a scatterer.