Prevention and Treatment of Nonfreezing Cold Injuries and Warm Water Immersion Tissue Injuries: Supplement to Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Frostbite.

We convened an expert panel to develop evidence-based guidelines for the evaluation, treatment, and prevention of nonfreezing cold injuries (NFCIs; trench foot and immersion foot) and warm water immersion injuries (warm water immersion foot and tropical immersion foot) in prehospital and hospital settings. The panel graded the recommendations based on the quality of supporting evidence and the balance between benefits and risks/burdens according to the criteria published by the American College of Chest Physicians. Treatment is more difficult with NFCIs than with warm water immersion injuries. In contrast to warm water immersion injuries that usually resolve without sequelae, NFCIs may cause prolonged debilitating symptoms, including neuropathic pain and cold sensitivity.

Plasma biomarkers of endothelial function, inflammation and oxidative stress in individuals with non-freezing cold injury.

NEW FINDINGS: What is the central question of this study? Are biomarkers of endothelial function, oxidative stress and inflammation altered by non-freezing cold injury (NFCI)? What is the main finding and its importance? Baseline plasma [interleukin-10] and [syndecan-1] were elevated in individuals with NFCI and cold-exposed control participants. Increased [endothelin-1] following thermal challenges might explain, in part, the increased pain/discomfort experienced with NFCI. Mild to moderate chronic NFCI does not appear to be associated with either oxidative stress or a pro-inflammatory state. Baseline [interleukin-10] and [syndecan-1] and post-heating [endothelin-1] are the most promising candidates for diagnosis of NFCI. ABSTRACT: Plasma biomarkers of inflammation, oxidative stress, endothelial function and damage were examined in 16 individuals with chronic NFCI (NFCI) and matched control participants with (COLD, n = 17) or without (CON, n = 14) previous cold exposure. Venous blood samples were collected at baseline to assess plasma biomarkers of endothelial function (nitrate, nitrite and endothelin-1), inflammation [interleukin-6 (IL-6), interleukin-10 (IL-10), tumour necrosis factor alpha and E-selectin], oxidative stress [protein carbonyl, 4-hydroxy-2-nonenal (4-HNE), superoxide dismutase and nitrotyrosine) and endothelial damage [von Willebrand factor, syndecan-1 and tissue type plasminogen activator (TTPA)]. Immediately after whole-body heating and separately, foot cooling, blood samples were taken for measurement of plasma [nitrate], [nitrite], [endothelin-1], [IL-6], [4-HNE] and [TTPA]. At baseline, [IL-10] and [syndecan-1] were increased in NFCI (P < 0.001 and P = 0.015, respectively) and COLD (P = 0.033 and P = 0.030, respectively) compared with CON participants. The [4-HNE] was elevated in CON compared with both NFCI (P = 0.002) and COLD (P < 0.001). [Endothelin-1] was elevated in NFCI compared with COLD (P < 0.001) post-heating. The [4-HNE] was lower in NFCI compared with CON post-heating (P = 0.032) and lower than both COLD (P = 0.02) and CON (P = 0.015) post-cooling. No between-group differences were seen for the other biomarkers. Mild to moderate chronic NFCI does not appear to be associated with a pro-inflammatory state or oxidative stress. Baseline [IL-10] and [syndecan-1] and post-heating [endothelin-1] are the most promising candidates for diagnosing NFCI, but it is likely that a combination of tests will be required.

The peripheral vascular responses in non-freezing cold injury and matched controls.

NEW FINDINGS: What is the central question of this study? Does non-freezing cold injury (NFCI) alter normal peripheral vascular function? What is the main finding and its importance? Individuals with NFCI were more cold sensitive (rewarmed more slowly and felt more discomfort) than controls. Vascular tests indicated that extremity endothelial function was preserved with NFCI and that sympathetic vasoconstrictor response might be reduced. The pathophysiology underpinning the cold sensitivity associated with NFCI thus remains to be identified. ABSTRACT: The impact of non-freezing cold injury (NFCI) on peripheral vascular function was investigated. Individuals with NFCI (NFCI group) and closely matched controls with either similar (COLD group) or limited (CON group) previous cold exposure were compared (n = 16). Peripheral cutaneous vascular responses to deep inspiration (DI), occlusion (PORH), local cutaneous heating (LH) and iontophoresis of acetylcholine and sodium nitroprusside were investigated. The responses to a cold sensitivity test (CST) involving immersion of a foot in 15°C water for 2 min followed by spontaneous rewarming, and a foot cooling protocol (footplate cooled from 34°C to 15°C), were also examined. The vasoconstrictor response to DI was lower in NFCI compared to CON (toe: 73 (28)% vs. 91 (17)%; P = 0.003). The responses to PORH, LH and iontophoresis were not reduced compared to either COLD or CON. During the CST, toe skin temperature rewarmed more slowly in NFCI than COLD or CON (10 min: 27.4 (2.3)°C vs. 30.7 (3.7)°C and 31.7 (3.9)°C, P < 0.05, respectively); however, no differences were observed during the footplate cooling. NFCI were more cold-intolerant (P < 0.0001) and reported colder and more uncomfortable feet during the CST and footplate cooling than COLD and CON (P < 0.05). NFCI showed a decreased sensitivity to sympathetic vasoconstrictor activation than CON and greater cold sensitivity (CST) compared to COLD and CON. None of the other vascular function tests indicated endothelial dysfunction. However, NFCI perceived their extremities to be colder and more uncomfortable/painful than the controls.

Peripheral sensory function in non-freezing cold injury patients and matched controls.

NEW FINDINGS: What is the central question of this study? Is peripheral sensory function impaired in the chronic phase of non-freezing cold injury (NFCI)? What is the main finding and its importance? Warm and mechanical detection thresholds are elevated and intraepidermal nerve fibre density is reduced in individuals with NFCI in their feet when compared to matched controls. This indicates impaired sensory function in individuals with NFCI. Interindividual variation was observed in all groups, and therefore a diagnostic cut-off for NFCI has yet to be established. Longitudinal studies are required to follow NFCI progression from formation to resolution ABSTRACT: The aim of this study was to compare peripheral sensory neural function of individuals with non-freezing cold injury (NFCI) with matched controls (without NFCI) with either similar (COLD) or minimal previous cold exposure (CON). Thirteen individuals with chronic NFCI in their feet were matched with the control groups for sex, age, race, fitness, body mass index and foot volume. All undertook quantitative sensory testing (QST) on the foot. Intraepidermal nerve fibre density (IENFD) was assessed 10 cm above the lateral malleolus in nine NFCI and 12 COLD participants. Warm detection threshold was higher at the great toe in NFCI than COLD (NFCI 45.93 (4.71)°C vs. COLD 43.44 (2.72)°C, P = 0.046), but was non-significantly different from CON (CON 43.92 (5.01)°C, P = 0.295). Mechanical detection threshold on the dorsum of the foot was higher in NFCI (23.61 (33.59) mN) than in CON (3.83 (3.69) mN, P = 0.003), but was non-significantly different from COLD (10.49 (5.76) mN, P > 0.999). Remaining QST measures did not differ significantly between groups. IENFD was lower in NFCI than COLD (NFCI 8.47 (2.36) fibre/mm2 vs. COLD 11.93 (4.04) fibre/mm2 , P = 0.020). Elevated warm and mechanical detection thresholds may indicate hyposensitivity to sensory stimuli in the injured foot for individuals with NFCI and may be due to reduced innervation given the reduction in IENFD. Longitudinal studies are required to identify the progression of sensory neuropathy from the formation of injury to its resolution, with appropriate control groups employed.

Faculty of Prehospital Care, Royal College of Surgeons Edinburgh guidance for medical provision for wilderness medicine.

To support leaders and those involved in providing medical care on expeditions in wilderness environments, the Faculty of Pre-Hospital Care (FPHC) of The Royal College of Surgeons of Edinburgh convened an expert panel of leading healthcare professionals and expedition providers. The aims of this panel were to: (1) provide guidance to ensure the best possible medical care for patients within the geographical, logistical and human factor constraints of an expedition environment. (2) Give aspiring and established expedition medics a 'benchmark' of skills they should meet. (3) Facilitate expedition organisers in selecting the most appropriate medical cover and provider for their planned activity. A system of medical planning is suggested to enable expedition leaders to identify the potential medical risks and their mitigation. It was recognised that the scope of practice for wilderness medicine covers elements of primary healthcare, pre-hospital emergency medicine and preventative medicine. Some unique competencies were also identified. Further to this, the panel recommends the use of a matrix and advisory expedition medic competencies relating to the remoteness and medical threat of the expedition. This advice is aimed at all levels of expedition medic, leader and organiser who may be responsible for delivering or managing the delivery of remote medical care for participants. The expedition medic should be someone equipped with the appropriate medical competencies, scope of practice and capabilities in the expedition environment and need not necessarily be a qualified doctor. In addition to providing guidance regarding the clinical competencies required of the expedition medic, the document provides generic guidance and signposting to the more pertinent aspects of the role of expedition medic.

The Ras-ERK MAPK regulatory network controls dedifferentiation in Caenorhabditis elegans germline.

How a committed cell can be reverted to an undifferentiated state is a central question in stem cell biology. This process, called dedifferentiation, is likely to be important for replacing stem cells as they age or get damaged. Tremendous progress has been made in understanding this fundamental process, but its mechanisms are poorly understood. Here we demonstrate that the aberrant activation of Ras-ERK MAPK signaling promotes cellular dedifferentiation in the Caenorhabditis elegans germline. To activate signaling, we removed two negative regulators, the PUF-8 RNA-binding protein and LIP-1 dual specificity phosphatase. The removal of both of these two regulators caused secondary spermatocytes to dedifferentiate and begin mitotic divisions. Interestingly, reduction of Ras-ERK MAPK signaling, either by mutation or chemical inhibition, blocked the initiation of dedifferentiation. By RNAi screening, we identified RSKN-1/P90(RSK) as a downstream effector of MPK-1/ERK that is critical for dedifferentiation: rskn-1 RNAi suppressed spermatocyte dedifferentiation and instead induced meiotic divisions. These regulators are broadly conserved, suggesting that similar molecular circuitry may control cellular dedifferentiation in other organisms, including humans.

Differential subcellular localization of DNA topoisomerase-1 isoforms and their roles during Caenorhabditis elegans development.

DNA topoisomerase-1 (TOP-1) resolves the topological problems associated with DNA replication, transcription and recombination by introducing temporary single-strand breaks in the DNA. Caenorhabditis elegans TOP-1 has two isoforms, TOP-1α and TOP-1ß. TOP-1ß is broadly localized to the nuclei of many cells at all developmental stages and concentrated in nucleoli in embryo gut and oogenic cells. However, TOP-1α is specifically localized to centrosomes, neuronal cells, excretory cells and chromosomes of germ cells in embryonic and larval stages. Reporter gene analysis also shows that top-1 transcription is highly activated in several sensory neurons, speculating the possible role of TOP-1α in neuronal development. From RNA interference (RNAi) experiments, we demonstrated that C. elegans TOP-1 is required for chromosomal segregation, germline proliferation and gonadal migration, which are all correlated with the expression and activity of TOP-1. Therefore, our findings may provide an insight into a new role of TOP-1 in development of multicellular organisms.

Post-transcriptional regulation of the Ras-ERK/MAPK signaling pathway.

The Ras-ERK/MAP (Mitogen-Activated Protein) kinase signaling pathway governs many cellular processes such as proliferation, differentiation, cell fate, homeostasis, and survival in all eukaryotes. Constitutive activation of the Ras-ERK/MAPK signaling pathway often leads to promotion of abnormal cell growth and tumorigenesis. Although the regulation of the Ras-ERK/MAPK signaling pathway by post-translational modification has been well elucidated, post-transcriptional regulations of this pathway are beginning to emerge in invertebrates and this work is extended to humans. In this review, we describe the conserved regulation of Ras-ERK/MAPK signaling by RNA-binding proteins (PUF, KH-domain, HuR, and LARP) and microRNAs (let-7 family miRNAs) and important implications for human diseases including cancers.

Caenorhabditis elegans DNA-2 helicase/endonuclease plays a vital role in maintaining genome stability, morphogenesis, and life span.

In eukaryotes, highly conserved Dna2 helicase/endonuclease proteins are involved in DNA replication, DNA double-strand break repair, telomere regulation, and mitochondrial function. The Dna2 protein assists Fen1 (Flap structure-specific endonuclease 1) protein in the maturation of Okazaki fragments. In yeast, Dna2 is absolutely essential for viability, whereas Fen1 is not. In Caenorhabditis elegans, however, CRN-1 (a Fen1 homolog) is essential, but Dna2 is not. Here we explored the biological function of C. elegans Dna2 (Cedna-2) in multiple developmental processes. We find that Cedna-2 contributes to embryonic viability, the morphogenesis of both late-stage embryos and male sensory rays, and normal life span. Our results support a model whereby CeDNA-2 minimizes genetic defects and maintains genome integrity during cell division and DNA replication. These finding may provide insight into the role of Dna2 in other multi-cellular organisms, including humans, and could have important implications for development and treatment of human conditions linked to the accumulation of genetic defects, such as cancer or aging.

Embryonic stem cells inhibit expression of erythropoietin in the injured spinal cord.

Recent observations have demonstrated neuroprotective role of erythropoietin (Epo) and Epo receptor in the central nervous system. Here we examined Epo function in the murine spinal cord after transplantation of pluripotent mouse embryonic stem (ES) cells pre-differentiated towards neuronal type following spinal cord injury. Expression of Epo was measured at both mRNA and protein levels in the ES cells as well as in the spinal cords after 1 and 7 days. Our data demonstrated that expression of Epo mRNA, as well as its protein content, in ES cells was significantly decreased after differentiation procedure. In the spinal cords, analysis showed that Epo mRNA level was significantly decreased after 1 day of ES cell injections in comparison to media-injected control. Epo protein level detected by Western blot was diminished as well. Examination of Epo production in the injured spinal cords after media or ES cells injections by indirect immunofluorescence showed increased Epo-immunopositive staining after media injections 1 day after injection. In contrast, ES cell transplantation did not induce Epo expression. Seven days after ES cell injections, Epo-immunopositive cells' distribution in the ipsilateral side was not changed, while the intensity of immunostaining on the contralateral side was increased, approaching levels in control media-injected tissues. Our data let us to presume that previously described immediate positive effects of ES cells injected into the injured zone of spinal cord are not based on Epo, but on other factors or hormones, which should be elucidated further.

Pre-differentiated embryonic stem cells promote neuronal regeneration by cross-coupling of BDNF and IL-6 signaling pathways in the host tissue.

The mechanism of embryonic stem (ES) cell therapeutic action remains far from being elucidated. Our recent report has shown that transplantation of ES cells, predifferentiated into neuronal progenitors, prevented appearance of chronic pain behaviors in mice after experimentally induced spinal cord injury. In the current study, we tested the hypothesis that this beneficial effect is mediated by antiapoptotic and regenerative signaling pathways activated in the host tissue by transplanted ES cells. Spinal cord injury was induced by unilateral microinjections of quisqualic acid at spinal levels T12-L2. At 1 week after injury, the pre-differentiated towards neuronal phenotype ES cells were transplanted into the site of injury. Here we show that transplantation of pre-differentiated ES cells activate both brain-derived neurotrophic factor (BDNF) and interleukin-6 (IL-6) signaling pathways in the host tissue, leading to activation of cAMP/PKA, phosporylation of cofilin and synapsin I, and promoting regenerative growth and neuronal survival.

Predifferentiated embryonic stem cells prevent chronic pain behaviors and restore sensory function following spinal cord injury in mice.

Embryonic stem (ES) cells have been investigated in repair of the CNS following neuronal injury and disease; however, the efficacy of these cells in treatment of postinjury pain is far from clear. In this study, we evaluated the therapeutic potential of predifferentiated mouse ES cells to restore sensory deficits following spinal cord injury (SCI) in mice. The pain model used unilateral intraspinal injection of quisqualic acid (QUIS) into the dorsal horn between vertebral levels T13 and L1. Seven days later, 60,000 predifferentiated ES cells or media were transplanted into the site of the lesion. Histological analysis at 7, 14, and 60 days post-transplantation revealed that animals receiving ES cell transplants suffered significantly less tissue damage than animals receiving media alone. Transplanted cells provided immediate effects on both spontaneous and evoked pain behaviors. Treatment with ES cells resulted in 0% (n = 28) excessive grooming behavior versus 60% (18 of 30) in media-treated animals. In the acetone test (to assess thermal allodynia), mice recovered to preinjury levels by 12 days after ES cell transplant, whereas control animals injected with media after SCI did not show any improvement up to 60 days. Similarly, the von Frey test (to assess mechanical allodynia) and the formalin test (to assess nociceptive hyperalgesia) showed that transplantation of predifferentiated ES cells significantly reduced these pain behaviors following injury. Here we show that predifferentiated ES cells act in a neuroprotective manner and provide antinociceptive and therapeutic effects following excitotoxic SCI.

Genital Chlamydia trachomatis infection in a subgroup of young men in the UK.

The frequency of genital Chlamydia trachomatis infection in young men in the UK has been found to be consistently lower than that in young women, but studies in such populations might have been affected by selection bias. We tested 798 male military recruits for chlamydia as part of their routine medical examination at Glencorse barracks in Scotland. 78 (9.8%) men were infected with chlamydia; rates of infection were similar in all age-groups. 69 (88%) chlamydia-positive men were asymptomatic. This rate is higher than those usually cited, showing the importance of opportunistic testing for chlamydia in men as well as in women.