Thermal windows on the body surface of African elephants (Loxodonta africana) studied by infrared thermography

In this study, we examined infrared thermograms in the course of time of six African zoo elephants and observed two phenomena. First, we noticed independent thermal windows, highly vascularised skin areas, on the whole elephants’ body and second we observed distinct and sharply delimited hot sections on the elephants’ pinnae. The frequency of thermal windows increased with increasing ambient temperature and body weight. We assume that the restriction of an enhanced cutaneous blood flow to thermal windows might enable the animal to react more flexibly to its needs with regard to heat loss. With this understanding, the use of thermal windows in heat loss might be seen as a fine-tuning mechanism under thermoneutral conditions.     

制革鞣制工艺在小布氏鲸皮张脱脂中的应用

在分析组织结构并测定脂肪含量的基础上,利用现代制革鞣制工艺对一头小布氏鲸(Balaenoptera edeni)的皮作了脱脂效果研究。在控制好对皮肤整体质量影响最小的情况下,本文设计了一套工艺流程,将脱脂操作贯穿到整个皮张的鞣制过程中。经组织切片和氯仿甲醇法检验,胸部和腹部真皮的脂肪体积比,由31.78%±2.69%和44.80%±3.74%下降至4.28%和6.83%;含脂量下降至4.04%和5.57%,脱脂率达到了86.24%和84.90%,基本满足了标本制作的脱脂要求。     

Validation of a dose tracking software for skin dose map calculation in interventional radiology

PurposeValidate the skin dose software within the radiation dose index monitoring system NEXO[DOSE]® (Bracco Injeneering S.A., Lausanne, Switzerland). It provides the skin dose distribution in interventional radiology (IR) procedures.MethodsTo determine the skin dose distribution and the Peak Skin Dose (PSD) in IR procedures, the software uses exposure and geometrical parameters taken from the radiation dose structured report and additional information specific to each angiographic system. To test the accuracy of the software, GafChromic® XR-RV3 films, wrapped under a cylindrical PMMA phantom, were irradiated with different setups. Calculations and films results are compared in terms of absolute dose and geometric accuracy, using two angiographic systems (Philips Integris Allura FD20, Siemens AXIOM-ArtisZeego).ResultsCalculated and film measured PSD values agree with an average difference of 7% ± 5%. The discrepancies in dose evaluation increase up to 33% in lower dose regions, because the algorithm does not consider the out-of-field scatter contribution of the neighboring fields, which is more significant in these areas. Regarding the geometric accuracy, the differences between the simulated dose spatial distributions and the measured ones are<3 mm (4%) in simple tests and 5 mm (5%) in setups closer to clinical practice. Moreover, similar results are obtained for the two studied angiographic system vendors.ConclusionsNEXO[DOSE]® provides an accurate skin dose distribution and PSD estimate. It will allow faster and more accurate monitoring of patient follow-up in the future.     

Diurnal Blood Pressure Variations Are Associated with Changes in Distal–Proximal Skin Temperature Gradient

It is generally assumed that skin vascular resistance contributes only to a small extent to total peripheral resistance and hence to blood pressure (BP). However, little is known about the impact of skin blood flow (SBF) changes on the diurnal variations of BP under ambulatory conditions. The main aim of the study was to determine whether diurnal patterns of distal SBF are related to mean arterial BP (MAP). Twenty-four-hour ambulatory measurements of BP, heart rate (HR) and distal (mean of hands and feet) as well as proximal (mean of sternum and infraclavicular region) skin temperatures were carried out in 51 patients (men/women?=?18/33) during a 2-d eye hospital investigation. The standardized ambulatory protocol allowed measurements with minimal interference from uncontrolled parameters and, hence, some conclusive interpretations. The distal minus proximal skin temperature gradient (DPG) provided a measure for distal SBF. Individual cross-correlation analyses revealed that the diurnal pattern of MAP was nearly a mirror image of DPG and hence of distal SBF. Scheduled lunch and dinner induced an increase in DPG and a decline in MAP, while HR increased. Low daytime DPG (i.e. low distal SBF) levels significantly predicted sleep-induced BP dipping (r?=??.436, p?=?.0014). Preliminary path analysis suggested that outdoor air temperature and atmospheric pressure may act on MAP via changed distal SBF. Changes in distal SBF may contribute to diurnal variation in MAP, including sleep-induced BP dipping and changes related to food intake. This finding might have an impact on individual cardiovascular risk prediction with respect to diurnal, seasonal and weather variations; however, the underlying mechanisms remain to be discovered.     

Changes in exercise and post-exercise core temperature under different clothing conditions

 This study evaluates the effect of different levels of insulation on esophageal (T _es) and rectal (T _re) temperature responses during and following moderate exercise. Seven subjects completed three 18-min bouts of treadmill exercise (75% VO_2max, 22°C ambient temperature) followed by 30 min of recovery wearing either: (1) jogging shoes, T-shirt and shorts (athletic clothing); (2) single-knit commercial coveralls worn over the athletic clothing (coveralls); or (3) a Canadian Armed Forces nuclear, bacteriological and chemical warfare protective overgarment with hood, worn over the athletic clothing (NBCW overgarment). T _es was similar at the start of exercise for each condition and baseline T _re was ∼0.4°C higher than T _es. The hourly equivalent rate of increase in T _es during the final 5 min of exercise was 1.8°C, 3.0°C and 4.2°C for athletic clothing, coveralls and NBCW overgarment respectively (P<0.05). End-exercise T _es was significantly different between conditions [37.7°C (SEM 0.1°C), 38.2°C (SEM 0.2°C and 38.5°C (SEM 0.2°C) for athletic clothing, coveralls and NBCW overgarment respectively)] (P<0.05). No comparable difference in the rate of temperature increase for T _re was demonstrated, except that end-exercise T _re for the NBCW overgarment condition was significantly greater (0.5°C) than that for the athletic clothing condition. There was a drop in T _es during the initial minutes of recovery to sustained plateaus which were significantly (P<0.05) elevated above pre-exercise resting values by 0.6°C, 0.8°C and 1.0°C, for athletic clothing, coveralls, and NBCW overgarment, respectively. Post-exercise T _re decreased very gradually from end-exercise values during the 30-min recovery. Only the NBCW overgarment condition T _re was significantly elevated (0.3°C) above the athletic clothing condition (P<0.05). In conclusion, T _es is far more sensitive in reflecting the heat stress of different levels of insulation during exercise and post-exercise than T _re. Physiological mechanisms are discussed as possible explanations for the differences in response. Received: 30 June 1998 / Accepted: 19 February 1999     

A novel antimicrobial peptide from skin secretions of the earthworm, Pheretima guillelmi (Michaelsen)

A novel lumbricin-like antimicrobial peptide named lumbricin-PG was isolated from skin secretions of the earthworm, Pheretima guillelmi (Michaelsen), using a procedure of one step Sephadex G-50 gel filtration and one step C₈ reverse-phase high-performance liquid chromatography (RP-HPLC). Its amino acid sequence was determined as FSRYARMRDSRPWSDRKNNYSGPQFTYPPEKAPPEKLIKWNN EGSPIFEMPAEGGHIEP by Edman degradation combined with cDNA cloning and mass spectrometry analysis. The cDNA encoding lumbricin-PG was cloned by cDNA library screening. The predicted protein from the cDNA sequence was composed of 73 amino acid residues including a mature lumbricin-PG and predicted signal peptide. It showed similarity with lumbricin antimicrobial peptide from the earthworm, Lumbricus rubellus by BLAST search. Purified lumbricin-PG exerted potential antimicrobial activities against bacteria and fungi; it showed weak hemolysis activity against human and rabbit red cells.     

Antibacterial peptide pleurocidin forms ion channels in planar lipid bilayers

Pleurocidin, a 25-residue α helical cationic peptide, isolated from skin mucous secretions of the winter flounder, displays a strong anti-microbial activity and appears to play a role in innate host defence. This peptide would be responsible for pore formation in the membrane of bacteria leading to lysis and therefore death. In this study, we investigated the behaviour of pleurocidin in different planar lipid bilayers to determine its mechanism of membrane permeabilisation. Macroscopic conductance experiments showed that pleurocidin did not display a pore-forming activity in neutral phosphatidylcholine/phosphatidylethanolamine (PC/PE) lipid bilayers. However, in 7:3:1 PC/PE/phosphatidylserine (PS) lipid bilayers, pleurocidin showed reproducible I/V curves at different peptide concentrations. This activity is confirmed by single-channel experiments since well-defined ion channels were obtained if the lipid mixture was containing an anionic lipid (PS). The ion channel characteristics such as—no voltage dependence, only one unitary conductance, linear relation ship current-voltage—, are not in favour of the membrane permeabilisation according to the barrel model but rather by the toroidal pore formation.     

Specific cleavage of beta-amyloid peptides by a metallopeptidase from Xenopus laevis skin secretions

Dactylysin (EC 3.5.24.60) is a metalloendopeptidase first isolated from the skin granular gland secretions of Xenopus laevis. This peptidase hydrolyzes bonds on the amino-terminus of singlets and between doublets of hydrophobic amino acids and was considered to play a role in the in vivo inactivation of biologically active regulatory peptides. Here, we show that dactylysin has also the ability to cleave human β[1-40]-amyloid peptide and related peptides. Cleavage of the wild type β[1-40]-amyloid peptide form, and to a lesser extent Flemish and Dutch mutants, occurred predominantly at the His¹⁴-Glu¹⁵ bond. We demonstrate that frog skin exudate contains a full-length amyloid protein precursor detected by immunochemical cross-reactivity with monoclonal antibody against C-terminal human amyloid protein precursor. The possibility that dactylysin, might be involved in normal catabolism of β amyloid peptide of Xenopus laevis is discussed.