Nurse rock microclimates significantly buffer exposure to freezing T temperature and moderate summer temperature

Nurse tree canopies mitigate exposure to freezing temperatures that could result in injury or mortality to the saguaro cactus (Carnegiea gigantea). Abiotic objects have been hypothesized to provide similar beneficial microclimates. We used data loggers at 11 nurse rock sites to record daily daytime summer maximum and winter nighttime minimum temperatures at Saguaro National Park, Arizona, to examine the effectiveness of rocks to moderate seasonal temperature extremes in the microclimate. Temperatures at rock sites averaged 2 °C warmer than exposed open control sites in winter. We found that the efficiency of rocks to act as insulators significantly increased as temperature at control sites decreased, consistent with studies of tree canopies, and that the insulation effect lasted throughout the night. In summer, rocks reduced exposure to maximum temperatures but did not offer significantly more cooling at higher temperatures. Our results suggest that the protection from freezing temperature offered by rocks in winter is more ecologically beneficial to the saguaro than extreme temperature amelioration during summer in the cold-limited frontiers of the species’ range

Nurse rock microclimates significantly buffer exposure to freezing T temperature and moderate summer temperature

Nurse tree canopies mitigate exposure to freezing temperatures that could result in injury or mortality to the saguaro cactus (Carnegiea gigantea). Abiotic objects have been hypothesized to provide similar beneficial microclimates. We used data loggers at 11 nurse rock sites to record daily daytime summer maximum and winter nighttime minimum temperatures at Saguaro National Park, Arizona, to examine the effectiveness of rocks to moderate seasonal temperature extremes in the microclimate. Temperatures at rock sites averaged 2 °C warmer than exposed open control sites in winter. We found that the efficiency of rocks to act as insulators significantly increased as temperature at control sites decreased, consistent with studies of tree canopies, and that the insulation effect lasted throughout the night. In summer, rocks reduced exposure to maximum temperatures but did not offer significantly more cooling at higher temperatures. Our results suggest that the protection from freezing temperature offered by rocks in winter is more ecologically beneficial to the saguaro than extreme temperature amelioration during summer in the cold-limited frontiers of the species’ range

Post-COVID symptoms reported at asynchronous virtual review and stratified follow-up after COVID-19 pneumonia.

BACKGROUND: The COVID-19 pandemic has strained healthcare systems and how best to address post-COVID health needs is uncertain. Here we describe the post-COVID symptoms of 675 patients followed up using a virtual review pathway, stratified by severity of acute COVID infection. METHODS: COVID-19 survivors completed an online/telephone questionnaire of symptoms after 12+ weeks and a chest radiograph. Dependent on findings at virtual review, patients were provided information leaflets, attended for investigations and/or were reviewed face-to-face. Outcomes were compared between patients following high-risk and low-risk admissions for COVID pneumonia, and community referrals. RESULTS: Patients reviewed after hospitalisation for COVID pneumonia had a median of two ongoing physical health symptoms post-COVID. The most common was fatigue (50.3% of high-risk patients). Symptom burden did not vary significantly by severity of hospitalised COVID pneumonia but was highest in community referrals. Symptoms suggestive of depression, anxiety and post-traumatic stress disorder were common (depression occurred in 24.9% of high-risk patients). Asynchronous virtual review facilitated triage of patients at highest need of face-to-face review. CONCLUSION: Many patients continue to have a significant burden of post-COVID symptoms irrespective of severity of initial pneumonia. How best to assess and manage long COVID will be of major importance over the next few years

Effect of peroxynitrite on plasma extravasation, microvascular blood flow and nociception in the rat

1. Peroxynitrite (ONOO(−)) is a cytotoxic species, formed by the reaction between nitric oxide and superoxide free radicals, that may be involved in inflammation. In this study we have investigated the effect of peroxynitrite on plasma extravasation and microvascular blood flow in the dorsal skin and on nociceptive responses in the hind paw of the rat. 2. Male Wistar rats were anaesthetized and their dorsal skin shaved. Plasma extravasation was measured by the extravascular accumulation of (125)I-labelled albumin over 0–45 min and 0–240 min. Blood flow was measured by laser-Doppler flowmetry over 0–240 min. Studies in the hind paw were carried out in the conscious rat. Hind paw weight changes were determined by volume displacement and nociception by a mechanical hyperalgesia technique. 3. Intradermal (i.d.) peroxynitrite (100–200 nmol site(−1)) produced a significant (P<0.01) dose-dependent increase in plasma extravasation in dorsal skin over 0–45 min which was not increased over 45–240 min. Plasma extravasation was significantly (P<0.001) decreased in rats pretreated with the anti-inflammatory steroid dexamethasone (1 mg kg(−1), i.v.; −180 min), but not modulated by treatment with the hydrogen peroxide deactivator catalase (2200 u site(−1)), or the superoxide scavenger superoxide dismutase (500 u site(−1)), effective doses of the tachykinin NK(1) antagonist SR140333 (1 nmol site(−1)), the cyclo-oxygenase inhibitor indomethacin (358 μmol site(−1)), or combined pretreatment with mepyramine (histamine H(1)-receptor antagonist; 2.8 nmol site(−1)) and methysergide (5-HT antagonist; 1.9 nmol site(−1)). 4. Microvascular blood flow was significantly (P<0.05) increased 30 and 120 min after i.d. peroxynitrite (100 nmol site(−1)) in dorsal skin and remained raised until the end of the recording period (240 min). The increase in blood flow was unaffected by dexamethasone (1 mg kg(−1), i.v.; −180 min) or indomethacin (10 mg kg(−1), s.c.; −30 min). 5. Hind paw volume was significantly (P<0.001) increased 30 min after intraplantar peroxynitrite (87.5 and 175 nmol paw(−1)) and remained raised for the duration of the experiment (360 min). By comparison, nociception was not altered by intraplantar peroxynitrite. 6. These data indicate that peroxynitrite can cause an increase in both plasma extravasation and blood flow, suggesting that peroxynitrite could be of biological relevance to microvascular responses. These findings may be of importance in the pathology of inflammatory diseases in which peroxynitrite formation occurs