3D morphometric study of domestic fowl glomerulus—A scanning electron microscope study of vascular corrosion casts     

Nedžad Hadžiomerović  Rizah Avdić  Bernd Minnich  Katharina Erlbacher  Nadžida Mlaćo  Faruk Tandir  Pamela Bejdić 《Anatomia, histologia, embryologia》2021,50(3):678-682

Microvascularization of domestic fowl kidneys was studied using scanning electron microscopy (SEM) of vascular corrosion casts (VCCs). Two types of nephrons, mammalian-type (MT) and reptilian-type (RT) nephrons and their glomerular structure were analysed quantitatively by 3D morphometry. A significant difference in shape and size between the MT and RT glomeruli was found. The mean diameter of the RT glomeruli was about 56 µm, while that of MT glomeruli was significantly larger, namely about 80 µm. The afferent arterioles in mammalian-type glomeruli usually bifurcated into two lobular branches and formed a complex glomerular capillary network with numerous loops. Reptilian-type glomeruli consisted of a single capillary forming few loops and leaving the glomerulus as efferent arteriole. Diameters of afferent and efferent arteriolar replicas were similar in all three kidney divisions of MT and RT nephrons. The absence of the interconnecting branches between the MT nephron capillaries at the gross inspection suggests that the mammalian-type nephron glomeruli, although more complex than the reptilian type, are not equivalent to those in mammalian kidneys.  相似文献   

Quantitative pollen requirements of solitary bees: Implications for bee conservation and the evolution of bee–flower relationships     

Andreas Müller  Stefan Diener  Simone Schnyder  Katharina Stutz  Claudio Sedivy  Silvia Dorn 《Biological conservation》2006,130(4):604-615

Knowledge about the quantitative pollen requirements of solitary bees is crucial for the preservation of endangered bee species and the understanding of the evolution of bee–flower relationships. We estimate the number of flowers required to rear a single larva for 41 European bee species (i) by comparing the pollen content of brood cells with the pollen quantity contained in the flowers of the bees’ host plants and (ii) by deducing the pollen requirements from a regression model describing the relationship between the average bee dry body mass and the average brood cell pollen content. The flower requirements of the bee species examined vary by three orders of magnitude. Depending on both bee species and host plant, from seven to 1100 flowers or from 0.9 to 4.5 flower heads are needed to rear a single larva. As only about 40% of the pollen contained in a flower was found to be available to a single female bee, these minimal figures have to be multiplied by a factor of approximately 2.5 to obtain a realistic estimate of bee flower requirements. The amount of pollen lost from flowers for bee nutrition is surprisingly high. We hypothesize that the recent decline of many bee species may have its main cause in a food shortage provoked by a decrease in flower diversity and quantity following habitat destruction and modern agricultural practices. The substantial pollen losses to bees as documented in this study support earlier findings on floral adaptations against excessive pollen harvesting by bees.  相似文献   

Astronomy. Brown dwarfs--faint at heart, rich in chemistry     

Lodders K 《Science (New York, N.Y.)》2004,303(5656):323-324

  相似文献   

Southern Hemisphere water mass conversion linked with North Atlantic climate variability     

Pahnke K  Zahn R 《Science (New York, N.Y.)》2005,307(5716):1741-1746

Intermediate water variability at multicentennial scales is documented by 340,000-year-long isotope time series from bottom-dwelling foraminifers at a mid-depth core site in the southwest Pacific. Periods of sudden increases in intermediate water production are linked with transient Southern Hemisphere warm episodes, which implies direct control of climate warming on intermediate water conversion at high southern latitudes. Coincidence with episodes of climate cooling and minimum or halted deepwater convection in the North Atlantic provides striking evidence for interdependence of water mass conversion in both hemispheres, with implications for interhemispheric forcing of ocean thermohaline circulation and climate instability.  相似文献   

NIR-spectroscopic investigation of foliage of ozone-stressed <Emphasis Type="Italic">Fagus sylvatica</Emphasis> trees     

Martina?G?b  Katharina?Hoffmann  Melanie?Lobe  Rut?Metzger  Sven van?Ooyen  Gereon?ElbersEmail author  Barbara?K?llner 《Journal of Forest Research》2006,11(2):69-75

Near infrared (NIR) reflectance spectroscopy was tested as a fast method for characterizing the toxic effects of air pollution on trees. Fagus sylvatica was exposed to known, different levels of ozone during summer of 2003 in plant chambers. Leaves were taken from the plants and NIR spectra were recorded. In order to derive calibration models, reference analyses were carried out and soluble carbohydrates were determined by an enzymatic method. Minor components, like α-tocopherol, were measured after solvent extraction using gas chromatography-mass spectrometry. A partial least squares (PLS) algorithm was used to perform the chemometric analyses. Good or in some cases very good calibration statistics expressed in terms of root mean square error of cross validation and R² were obtained for glucose, fructose, sucrose, and α-tocopherol. In addition, a better than expected correlation between the NIR spectra of the leaves and the ozone concentration in the plant chambers was observed. NIR spectroscopy appears to be a very useful method to simultaneously determine many components in leaves that are related to the health of trees. It is obviously able to quantitatively describe the changing patterns of constituents in leaves of trees caused by toxic substances. Thus, NIR spectroscopy can be a very effective tool for environmental biomonitoring, especially for observation of forests.  相似文献   

Application of stable carbon isotope analysis to the detection of testosterone administration to cattle     

Hebestreit M  Flenker U  Buisson C  Andre F  Le Bizec B  Fry H  Lang M  Weigert AP  Heinrich K  Hird S  Schänzer W 《Journal of agricultural and food chemistry》2006,54(8):2850-2858

The use of anabolic substances is prohibited in food-producing animals throughout the European Union. No method is available to reliably detect the misuse of natural hormones in cattle. A method was developed to detect the abuse of testosterone in cattle fattening. Synthesized testosterone is rather depleted in the (13)C/(12)C ratio. Hence, the method is based on gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) analysis of urine. To select testosterone metabolites and endogenous reference compounds (ERC), the concentration of urinary steroids of cattle was investigated. Dehydroepiandrosterone and androst-5ene-3beta,17alpha-diol were chosen as ERCs to show endogenous (13)C/(12)C ratios. Etiocholanolone and 5alpha-androstane-3beta,17alpha-diol were chosen as the most important testosterone metabolites. Other metabolites known from literature like epitestosterone were less promising. In principle, GC/C/IRMS is a nonspecific method because finally carbon dioxide is analyzed. Therefore, a dedicated cleanup procedure for the selected steroids was developed. By means of proposed confidence intervals in the isotopic composition of ERCs and metabolites, the administration of testosterone to cattle could be detected reliably. Differences of up to 11 per thousand on the delta-scale between ERC and testosterone metabolites were found after testosterone administration, whereas endogenous differences did not exceed 2 per thousand.  相似文献   

Authentication of the botanical and geographical origin of honey by mid-infrared spectroscopy   总被引：1，自引：0，他引：1  

Ruoff K  Luginbühl W  Künzli R  Iglesias MT  Bogdanov S  Bosset JO  von der Ohe K  von der Ohe W  Amado R 《Journal of agricultural and food chemistry》2006,54(18):6873-6880

The potential of Fourier transform mid-infrared spectroscopy (FT-MIR) using an attenuated total reflectance (ATR) cell was evaluated for the authentication of 11 unifloral (acacia, alpine rose, chestnut, dandelion, heather, lime, rape, fir honeydew, metcalfa honeydew, oak honeydew) and polyfloral honey types (n = 411 samples) previously classified with traditional methods such as chemical, pollen, and sensory analysis. Chemometric evaluation of the spectra was carried out by applying principal component analysis and linear discriminant analysis, the error rates of the discriminant models being calculated by using Bayes' theorem. The error rates ranged from <0.1% (polyfloral and heather honeys as well as honeydew honeys from metcalfa, oak, and fir) to 8.3% (alpine rose honey) in both jackknife classification and validation, depending on the honey type considered. This study indicates that ATR-MIR spectroscopy is a valuable tool for the authentication of the botanical origin and quality control and may also be useful for the determination of the geographical origin of honey.  相似文献   

Clinical evaluation of intranasal medetomidine–ketamine and medetomidine–S(+)-ketamine for induction of anaesthesia in rabbits in two centres with two different administration techniques     

Linda C. Weiland  Katharina Kluge  Annette P.N. Kutter  Peter W. Kronen 《Veterinary anaesthesia and analgesia》2017,44(1):98-105

Objective

The aim was to compare efficacy and side effects of induction with medetomidine–ketamine or medetomidine–S(+)-ketamine by intranasal (IN) instillation in rabbits and to evaluate both protocols during subsequent isoflurane anaesthesia.

Study design

Prospective, blinded, randomized experimental study in two centres.

Animals

Eighty-three healthy New Zealand White rabbits undergoing tibial or ulnar osteotomy.

Methods

Medetomidine (0.2 mg kg^?1) with 10 mg kg^?1 ketamine (MK) or 5 mg kg^?1 S(+)-ketamine (MS) was administered IN to each rabbit in a randomized fashion. In Centre 1 (n = 42) rabbits were held in sternal recumbency, and in Centre 2 (n = 41) in dorsal recumbency, during drug instillation. Adverse reactions were recorded. If a rabbit swallowed during endotracheal intubation, half of the initial IN dose was repeated and intubation was re-attempted after 5 minutes. Anaesthesia was maintained with isoflurane. Heart rate, blood pressure, endtidal carbon dioxide concentration and blood gases were recorded. Data were analysed using Student's t-test, Mann–Whitney test and Fisher's exact test.

Results

In all, 39 animals were assigned to the MK group and 44 to the MS group. Two rabbits in the MS group held in dorsal recumbency died after instillation of the drug. Eight (MK) and 11 rabbits (MS) were insufficiently anaesthetized and received a second IN dose. One rabbit in MK and three in MS required an isoflurane mask induction after the second IN dose. There were no significant differences between treatments for induction, intraoperative data, blood gas values and recovery data.

Conclusion and clinical relevance

This study indicated that medetomidine–ketamine and medetomidine-S(+)-ketamine were effective shortly after IN delivery, but in dorsal recumbency IN administration of S(+)-ketamine led to two fatalities. Nasal haemorrhage was noted in both cases; however, the factors leading to death have not been fully elucidated.  相似文献   

A non-stochastic portfolio model for optimizing the transformation of an even-aged forest stand to continuous cover forestry when information about return fluctuation is incomplete     

Katharina Messerer  Hans Pretzsch  Thomas Knoke 《Annals of Forest Science》2017,74(2):45

  相似文献   

Randomized field trial comparing the efficacy of florfenicol and oxytetracycline in a natural outbreak of calf pneumonia using lung reaeration as a cure criterion     

Stan Jourquin  Jade Bokma  Lieze De Cremer  Katharina van Leenen  Nick Vereecke  Bart Pardon 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2022,36(2):820

BackgroundRespiratory infections are the main indication for antimicrobial use in calves. Optimal treatment duration currently is unknown, but shorter duration would likely decrease selection for antimicrobial resistance.Hypothesis/ObjectivesDetermine differences in cure rate and healing time between animals treated with florfenicol and oxytetracycline in a natural outbreak of respiratory disease using reaeration observed on thoracic ultrasound examination as healing criterion.AnimalsCommercial farm housing 130, 3 to 9 month old Belgian blue beef calves.MethodsRandomized clinical trial during an outbreak of respiratory disease. Metaphylactic treatment was initiated, randomly treating animals with either florfenicol or oxytetracycline. Ultrasonographic follow‐up was done the first day and every other day for a 14‐day period. At the individual animal level, treatment was discontinued when reaeration of the lungs occurred. Differences in cure rate and healing time were determined.ResultsOf the 130 animals studied, 67.7% developed a lung consolidation ≥0.5 cm. The mean ultrasonographic healing time was 2.5 days in the florfenicol group compared to 3.1 days in the oxytetracycline group (P = .04). After single treatment, 80.6% and 60.3% had no consolidations in the florfenicol and oxytetracycline groups, respectively (P = .01). A Mycoplasma bovis strain was genetically and phenotypically determined to be susceptible to both antimicrobials.Conclusions and Clinical ImportanceUltrasonographic lung reaeration shows potential as a cure criterion to rationalize antimicrobial use for outbreaks of pneumonia. In our study, florfenicol resulted in a faster cure and higher reduction in antimicrobial usage than did oxytetracycline.  相似文献