A panic attack-like unusual stress reaction

Ever since the seminal studies of Hans Selye, activation of hypothalamus-pituitary-adrenal (HPA) axis is emblematic of stress. Consequently, the lack of HPA axis responses following the undisputable psychological stress of a panic attack stands out as one of the most intriguing findings of contemporary psychiatry. On the other hand, the defensive behaviors and aversive emotions produced by stimulation of the dorsal periaqueductal gray matter (DPAG) have been proposed as a model of panic attacks. Therefore, we examined whether the plasma levels of ‘stress hormones’ corticotropin and prolactin show any change following the DPAG-evoked freezing and flight behaviors of the rat. Rats bearing an electrode into the DPAG and an intra-atrial catheter were stimulated at 9:00 a.m., 18–24 h after the catheter implantation. Blood samples were withdrawn just before 1-min stimulation of DPAG, immediately after (5 or 15 min) and throughout 3 to 27 h following stimulation. In another experiment, samples were withdrawn either before or following a prolonged stimulation (5 min) of the DPAG with flight threshold intensity. Hormones were measured by either chemiluminescent or double-antibody immunoassays. Hormone plasma levels following freezing and flight behaviors were compared to those of resting or restraint-stressed rats. Data show that stress hormones remain unaltered following the DPAG-evoked defensive behaviors. Not even the 5-min stimulation of DPAG with the flight threshold intensity changed corticotropin plasma levels significantly. As far as we known, this is the first demonstration of the lack of stress hormone responses following the intense emotional arousal and physical exertion of a fear-like behavior in rats. Data add new evidence of DPAG involvement in spontaneous panic attacks.     

Octocoral bleaching during unusual thermal stress

We describe a bleaching event in octocoral communities at four reefs in southwest Puerto Rico during October 2005 following a period of elevated sea surface temperatures. Percentages of colonies bleached varied among taxa, ranging from 0% for Pseudopterogorgia, Eunicea and Gorgonia to over 90% for Muricea. Other taxa exhibiting bleaching included Pseudoplexaura (22.3%), Muriceopsis (36.6%), Briareum (46.1%), Plexaurella (69.6%) and Pterogorgia (84.5%).     

Sleeping blood,tremor and paralysis: A trans-cultural approach to an unusual conversion reaction

An unusual conversion reaction and a related folk belief system are described in a Cape Verdean-American woman. A clinical approach is presented which stresses the need to negotiate between professional and popular explanatory models of illness. It is suggested that a significant factor in the successful management of this patient's symptoms was the acceptance of a mutually-understandable idiom for communication and treatment.     

A genetic study of panic disorder pedigrees.

Pedigree analysis is done on 19 kindreds of panic disorder, and the results suggest that this disorder is transmitted as an autosomal dominant trait. Seven of these 19 kindreds were ascertained through a panic disorder proband with mitral valve prolapse. When the analysis is done omitting these seven kindreds, the results also suggest that panic disorder without prolapse is transmitted as an autosomal dominant trait.     

The reaction of thymocytes to hypoxic stress

The reaction of thymocytes to hypoxic stress has been investigated according to indices of nucleic acid exchange. Acute and moderate, though long-term, hypoxia noticeably depresses DNA and RNA syntheses in rat thymocytes. Activation of nucleic acid repair synthesis during restoration of the organ takes place only if the hypoxic effect alternates with periods of normoxia. Under conditions of continuous prolonged hypoxia (high altitude), the adaptation is achieved by a decrease in thymocyte nucleic acid exchange. The role of thymocytes in the homeostasis-maintaining mechanisms, as the organism becomes adapted to hypoxia through different training conditions, is discussed.     

Oncogenes induce genotoxic stress by mitotic processing of unusual replication intermediates

Oncogene-induced DNA replication stress activates the DNA damage response (DDR), a crucial anticancer barrier. DDR inactivation in these conditions promotes genome instability and tumor progression, but the underlying molecular mechanisms are elusive. We found that overexpression of both Cyclin E and Cdc25A rapidly slowed down replication forks and induced fork reversal, suggestive of increased topological stress. Surprisingly, these phenotypes, per se, are neither associated with chromosomal breakage nor with significant DDR activation. Oncogene-induced DNA breakage and DDR activation instead occurred upon persistent G2/M arrest or, in a checkpoint-defective context, upon premature CDK1 activation. Depletion of MUS81, a cell cycle–regulated nuclease, markedly limited chromosomal breakage and led to further accumulation of reversed forks. We propose that nucleolytic processing of unusual replication intermediates mediates oncogene-induced genotoxicity and that limiting such processing to mitosis is a central anti-tumorigenic function of the DNA damage checkpoints.     

小麦苗期对1, 2, 4-三氯苯胁迫的生理响应

通过砂培试验,研究了6种浓度(0、0.3、0.6、1.0、1.5 mmol/kg沙和2.0 mmol/kg沙)的1, 2, 4-三氯苯(TCB)对两种小麦烟辐188(耐性基因型)和扬麦16(敏感基因型)种子发芽率、发芽指数、幼苗生物量、以及叶片和根系的蛋白质含量、丙二醛含量(MDA)、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、过氧化氢酶(CAT)活性等生理指标的影响.结果表明两种小麦基因型具有显著的差异,在TCB胁迫下,烟辐188的种子发芽率、发芽指数、幼苗生物量均高于扬麦16,烟辐188和扬麦16的叶片可溶性蛋白含量分别与对照差异不显著和显著偏低.随着TCB浓度的升高,烟辐188根系的可溶性蛋白含量呈上升趋势,与对照差异显著,而扬麦16先略有上升然后呈下降趋势,且显著低于对照.TCB胁迫导致扬麦16叶片SOD、POD活性小于对照,CAT活性显著小于对照;而烟辐188叶片SOD活性与对照间差异不明显,POD和CAT活性在低浓度TCB胁迫时与对照差异不大,在高浓度时小于对照,其MDA含量低于扬麦16.烟辐188根系SOD、POD活性对TCB胁迫不敏感,扬麦16 SOD、POD活性受O-·2诱导而上升,但由于其O-·2产生速率要大于烟辐188,仍然不能清除多余的O-·2,最终其根系MDA含量高于烟辐188.总体而言,TCB胁迫下烟辐188的发芽情况、幼苗生长情况和生理指标均好于扬麦16,表现出对TCB胁迫有较强的耐受性和适应性.     

Orthostatic panic as a key Vietnamese reaction to traumatic events: the case of September 11, 2001

This article discusses a culturally specific response to traumatic events: orthostatic panic attacks among Vietnamese refugees. We compared the rate and severity of orthostatic panic as well as the rates and severity of associated flashbacks a month before and a month after September 11, 2001. After that date, the rate and severity of orthostatic panic greatly increased, as did the rate and severity of associated flashbacks. The central role of orthostatic panic as a response to traumatic events is illustrated through a patient's vignette. An explanation of why September 11 so profoundly influenced this population is adduced, including an explanation of why it resulted in considerable worsening of orthostatic panic.     

Ozone-induced oxidative stress: Mechanisms of action and reaction

In this review we explore several models which might explain ozone (O₃)-induced injury to plant foliage. Ozone enters the cell through the wall and plasma membrane where active oxygen species are generated. If the concentration of O₃ is very high, unregulated cell death will occur. Alternatively, the active oxygen species, or succeeding reaction products, may serve as elicitors of regulated plant responses. These regulated responses include the induction of ethylene which could serve as a primary signal for—or a facilitator of—subsequent responses. The role of regulated suppression of photosynthetic genes and induction of chitinases and β-1,3-glucanase in programmed cell death is explored. Induction of antioxidants, enzymes of lignification and glutathione- S -transferase are discussed in the context of O₃-induced cell repair or cell protection. A second model is postulated to explain induction of accelerated foliar senescence by low levels of O₃. The notion that O₃-induced elicitation of responses in the nucleus might lead to increased oxidative stress in the chloroplast is considered as a mechanism for accelerating the rate of degradation of ribulose-1,5-bisphosphate car-boxylase/oxygenase (Rubisco). The mechanisms by which O₃ induces loss of Rubisco, and the relationship to accelerated foliar senescence are discussed.