The use of the iron chelating agent desferrioxamine in rice cell cryopreservation: a novel approach for improving recovery

The iron chelating drug, desferrioxamine is used to suppress oxidative stress in mammalian transplant organs subjected to cold storage. The efficacy of desferrioxamine in improving post-thaw survival in cryopreserved cells from two rice culture lines was evaluated. Unfrozen rice cells maintained proliferation capacity over a fifteen day time course when exposed to concentrations of desferrioxamine > 10 mg·l⁻¹. Albeit, growth was reduced compared to controls. Short-term applications of the drug at concentrations of 0.5 and 10 mg·l⁻¹ before cryopreservation and during the early post-thaw period had a positive affect on recovery as assessed by cell proliferation and triphenyl tetrazolium chloride reduction capabilities. The pharmaceutical properties of desferrioxamine are attributed to iron sequestration and the prevention of harmful Fenton and free radical chemistry. However, desferrioxamine did not significantly reduce lipid peroxidation in cryopreserved rice cells.     

Oxidative stress adaptation improves postischemic ventricular recovery

Adaptation to various forms of stress has been found to be associated with increased cellular tolerance to myocardial ischemia. In this study, the effects of myocardial adaptation to oxidative stress was examined by injecting rats with endotoxin (0.5 mg/kg) and its non-toxic derivative, lipid A (0.5 mg/kg). Both compounds exerted oxidative stress within 1 h of treatment as evidenced by enhanced malonaldehyde formation. The oxidative stress disappeared steadily and progressively with time in concert with the appearance of the induction of glutathione and antioxidative enzymes that included superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase. After 24 h of endotoxin or lipid A treatment, the amount of oxidative stress and antioxidant enzyme levels were significantly lower and higher, respectively, compared to those at the baseline levels. Corroborating these results, both endotoxin and lipid A provided protection against myocardial ischemia and reperfusion injury as evidenced by significantly improved postischemic recovery of left ventricular functions. The data presented here demonstrates that a controlled amount of oxidative stress induces the expression of intracellular antioxidants that can result in enhanced myocardial tolerance to ischemia. This suggests that myocardial adaptation to oxidative stress may be a potential tool for reduction of ischemic/reperfusion injury.     

Changes in the macrophage population of the rat superior cervical ganglion after postganglionic nerve injury

Following peripheral nerve transection, a series of biochemical changes occurs in axons and Schwann cells both at the site of lesion and distal to it. Macrophages differentiated from monocytes that invade the area in response to transection (elicited macrophages) and, perhaps, also macrophages normally present in the tissue (resident macrophages) play important roles in these changes. In addition, nerve transection produces changes in the cell bodies of axotomized neurons and their surrounding glial cells, located at some distance from the lesion. To determine whether macrophages might play a role in the changes occurring in the superior cervical ganglion (SCG) after axotomy, we examined the presence of macrophages before and after axonal damage. The monoclonal antibodies ED1, ED2, and OX6 were used, each of which recognizes a somewhat different population of macrophages. Ganglia from normal rats contained a population of resident cells that were ED2+ but very few that were ED1+. Within 2 days after the postganglionic nerves were transected, the number of ED1+ cells increased substantially, with little change in immunostaining for ED2. These data, in combination with published studies on other tissues, suggest that ED1 in the SCG is selective for elicited macrophages and ED2 for resident macrophages. OX6 immunostaining was prominent in normal ganglia but also increased significantly after axotomy, suggesting that it reflects both macrophage populations. Systemic administration of 6-hydroxydopamine, a neurotoxin that causes the destruction of sympathetic nerve endings, also produced an increase in ED1 immunostaining. Thus, the change in ED1 immunostaining in the SCG does not require surgery, with the attendant servering of local blood vessels and connective tissue, but rather only the disconnection of sympathetic neurons from their end organs. The time course of the invasion of monocytes after axotomy indicates that this process is not required to trigger the biochemical changes occurring in the ganglion within the first 24 h. On the other hand, the existence of a resident population of macrophages raises the possibility that changes in those cells might be involved. © 1995 John Wiley & Sons, Inc.     

Histology of dart tag insertion sites in the epaulette shark

Samples of dermal and epidermal tissues of epaulette sharks Hemiscyllium ocellatum were examined histologically to assess damage caused by tagging. Tissues from around tag sites were removed at time intervals ranging from 100 min to 284 days post-tagging. These samples showed acute and chronic responses to tagging. Acute responses consisted of localized tissue breakdown and haemorrhaging, and occurred within the first few hours after tag insertion. At 10 h post-tagging, an intermediate response was apparent. This phase was characterized by further haemorrhaging and red and white blood cell movement into the wound area. The chronic response observed in the 10–284-day post-tagging samples was characterized by fibrous tissue formation to sequester the tag. This tissue presumably protects the adjacent musculature from further trauma produced by movement of the tag and provides a continuous barrier between the internal and external milieu. Tissue repair appeared to progress consistently in all specimens and no secondary infections at the tag site were seen. Tagging produced only localized tissue disruption and did not appear to be detrimental to the long term health of individual sharks. Our findings show that spaghetti style dart tagging is an acceptable method for marking individuals (40–75+ cm total length) of this species.     

NOCICEPTIVE RESPONSES IN INTERLEUKIN-6-DEFICIENT MICE TO PERIPHERAL INFLAMMATION AND PERIPHERAL NERVE SECTION

The cutaneous nociceptive response threshold to mechanical and thermal stimulation, the development of hyperalgesia and plasma extravasation after subcutaneous injection of carrageenan and the development of autotomy behaviour after nerve section were assessed in interleukin-6-deficient (IL-6^−/−) and age-matched wild-type (IL-6^+/+) mice. IL-6^−/−mice had significantly lower response threshold to both mechanical and thermal stimulation in comparison to IL-6^+/+controls. Both IL-6^−/−and IL-6^+/+mice developed hyperalgesia to mechanical and thermal stimulation after localized carrageenan injection, but the magnitude of the hyperalgesia was less in the IL-6^−/−than in the IL-6^+/+controls. IL-6^−/−mice also exhibited less plasma extravasation after carrageenan injection. No difference was noted between males and females in basal nociception and inflammatory hyperalgesia. However, female IL-6^−/−mice exhibited autotomy behaviour, a sign of neuropathic pain, significantly more frequently and after a shorter interval following peripheral nerve injury than male IL-6^−/−or male and female IL-6^+/+mice. It is suggested that IL-6^−/−mice exhibited numerous changes in nociceptive responses compared to controls, some of which are sex related. The mechanisms of these changes in relation to null-mutation of the IL-6 gene and the influence of genetic background are discussed.     

杏种子超低温伤害的研究

液氮保存杏种子伤害情况大体分为三类。整个子叶伤害后,只要种胚具有活力,仍能用组织培养方法获得新植株。子叶局部损伤,延迟种子萌发３－４ｄ,萌发后１２ｄ左右的期间内,苗木生长稍慢。种胚伤害,则不能成苗。随着种子损伤程度的增加,电解质渗出率也增加,说明杏种子超低温导致了质膜伤害。     

A retrospective,follow-up study of biofeedback-assisted relaxation therapy in patients with posttraumatic headache

Although biofeedback in the treatment of migraine and tension-type headache has been widely researched, there is little research examining biofeedback therapy in posttraumatic headache (PTH). In this retrospective study, 40 subjects with PTH who had received biofeedback-assisted relaxation at our headache clinic were questioned at least 3 months following the completion of therapy. Subjects were queried about improvements in headache, increases in ability to relax and cope with pain, and overall benefits, lasting effectiveness, and continued use of biofeedback in daily life. Results indicate 53% reported at least moderate improvement in headaches; 80% reported at least moderate improvement in ability to relax and cope with pain; 93% found biofeedback helpful to some degree; 85% felt headache relief achieved through biofeedback had continued at least somewhat; and 95% stated they were continuing to use biofeedback skills in daily life. A correlation analysis revealed a negative relationship between response to biofeedback and increased chronicity of the disorder. In other words, the more chronic the disorder, the poorer the response to treatment. A stepwise regression analysis found that chronicity of the disorder and number of treatment sessions significantly affected response to treatment. Data suggest that biofeedback-assisted relaxation should at least be considered when planning treatment strategies for posttraumatic headache.We wish to express our appreciation to Sandra Tomlinson Becky Kinloch, and C. M. Bundrick for their assistance in this project.     

Cyclosporin A binding in mitochondrial cyclophilin inhibits the permeability transition pore and protects hearts from ischaemia/reperfusion injury

When loaded with high (pathological) levels of Ca²⁺, mitochondria become swollen and uncoupled as the result of a large non-specific increase in membrane permeability. This process, known as the mitochondrial permeability transition (MPT), is exacerbated by oxidative stress and adenine nucleotide depletion. These conditions match those that a heart experiences during reperfusion following a period of ischaemia. The MPT is caused by the opening of a non-specific pore that can be prevented by sub-micromolar concentrations of cyclosporin A (CsA). A variety of conditions that increase the sensitivity of pore opening to [Ca²⁺], such as thiol modification, oxidative stress, increased matrix volume and chaotropic agents, all enhance the binding of matrix cyclophilin (CyP) to the inner mitochondrial membrane in a CsA-sensitive manner. In contrast, ADP, membrane potential and low pH decrease the sensitivity of pore opening to [Ca²⁺] without affecting CyP binding. We present a model of pore opening involving CyP binding to a membrane target protein followed by Ca²⁺-dependent triggering of a conformational change to induce channel opening. Using the ischaemic/reperfused rat heart we have shown that the mitochondrial pore does not open during ischaemia, but does do so during reperfusion. Recovery of heart during reperfusion is improved in the presence of 0.2 µM CsA, suggesting that the MPT may be critical in the transition from reversible to irreversible reperfusion injury. (Mol Cell Biochem 174: 167–172, 1997)     

The mitochondrial permeability transition in toxic, hypoxic and reperfusion injury

Opening of a non-specific, high conductance permeability transition pore or megachannel in the inner mitochondrial membrane causes onset of the mitochondrial permeability transition, which is characterized by mitochondrial swelling, depolarization and uncoupling. Inducers of the permeability transition include Ca²⁺, oxidant stress and a permissive pH greater than 7.0. Blockers include cyclosporin A, trifluoperazine and pH < 7. Using laser scanning confocal microscopy, we developed techniques to visualize onset of the mitochondrial permeability transition in situ in living cells. In untreated cells, the permeability transition pore is continuously closed and does not 'flicker' open. By contrast, the pore opens in liver and heart cells after exposure to oxidant chemicals, calcium ionophore, hypoxia and ischemia/reperfusion, causing mitochondrial uncoupling and aggravation of ATP depletion. In injury to hepatocytes from tert-butylhydroperoxide, an analog of lipid hydroperoxides generated during oxidative stress, onset of the mitochondrial permeability transition is preceded by oxidation of mitochondrial pyridine nucleotides, mitochondrial generation of oxygen radicals and an increase of mitochondrial Ca²⁺, all inducers of the mitochondrial permeability transition. In ischemia, the acidosis of anaerobic metabolism protects strongly against cell death. During reperfusion, recovery of pH to normal levels is a stress that actually precipitates cell killing. Onset of the mitochondrial permeability transition may be responsible, in part, for this pH-dependent injury, or pH paradox. The mitochondrial permeability transition may also be responsible for a variety of pathological phenomena. In particular, the mitochondrial permeability transition may underlie Reye's syndrome and Reye's-like drug toxicities. In conclusion, multiple mechanisms contribute to cell injury after hypoxia, ischemia/reperfusion and toxic chemicals, but a common final pathway leading to acute cellular nec rosis may be ATP depletion after mitochondrial failure. One important mechanism causing mitochondrial failure is the mitochondrial permeability transition, which both uncouples oxidative phosphorylation and accelerates ATP hydrolysis. Interventions that block this pH-dependent phenomenon protect against onset of cell death. (Mol Cell Biochem 174: 159–165, 1997)     

一氧化氮和肿瘤坏死因子在小鼠免疫性肝损伤中的作用及抗肝炎新药SY－801和SY－640的影响

本研究结果表明：一氧化氮（ＮＯ）在卡介苗（ＢＣＧ）加脂多糖（ＬＰＳ）诱导的免疫性肝损伤中呈现双向作用。来源于吞噬细胞的ＮＯ具有损伤作用,而其它来源的ＮＯ则具有保护作用。肿瘤坏死因子（ＴＮＦ）也参与了ＢＣＧ＋ＬＰＳ诱导的肝损伤。枯否氏细胞通过释放ＮＯ及ＴＮＦ而介导肝损伤。抗肝炎新药ＳＹ－８０１及ＳＹ－６４０的保肝机理与它们升高血浆ＮＯ及降低ＴＮＦ基因表达有关。