Glycerolipid formation and PGE2 and PGF2α production of rat renal papillae in vitro, the effects of urea

The glycerolipid production by rat renal papillary slices varied inversely with the urea concentration (0a–1660 mM) whether the production was measured as labelling of the glycerol backbone from glucose or as incorporation of labelled arachidonic acid and palmitic acid. The rate of phospholipid formation was most dependent on medium urea concentrations in the range between 0 and 1100 mM. The production of prostaglandins PGE₂ and PGF_2α, measured radioimmunologically or by an isotope derivative method was in the same range inversely related to the production of glycerolipids and chain elongations. The effect of urea on prostaglandin formation is probably indirectly caused by the inhibition of the phospholipid formation and chain elongation, since the effect was abolished by 1% defatted albumin in the medium. The data suggest that the level of free arachidonic acid within the cells is controlled to an important extent by glycerolipid formation and chain elongation.     

Molecular Characterization of Melanoma Cases in Denmark Suspected of Genetic Predisposition

Both environmental and host factors influence risk of cutaneous melanoma (CM), and worldwide, the incidence varies depending on constitutional determinants of skin type and pigmentation, latitude, and patterns of sun exposure. We performed genetic analysis of CDKN2A, CDK4, BAP1, MC1R, and MITFp.E318K in Danish high-risk melanoma cases and found CDKN2A germline mutations in 11.3% of CM families with three or more affected individuals, including four previously undescribed mutations. Rare mutations were also seen in CDK4 and BAP1, while MC1R variants were common, occurring at more than twice the frequency compared to Danish controls. The MITF p.E318K variant similarly occurred at an approximately three-fold higher frequency in melanoma cases than controls. To conclude, we propose that mutation screening of CDKN2A and CDK4 in Denmark should predominantly be performed in families with at least 3 cases of CM. In addition, we recommend that testing of BAP1 should not be conducted routinely in CM families but should be reserved for families with CM and uveal melanoma, or mesothelioma.     

On lipid droplets in renal interstitial cells

Summary By ultracentrifugation of homogenates of rat renal papillae, a low density layer composed of small primary fluorescing lipid droplets was isolated. Probably the isolated lipid material originates mainly from the primary fluorescing lipid droplets of the renal interstitial cells. The isolated lipid droplets were mainly triglycerides, cholesterol esters and free longchain fatty acids. The long-chain fatty acid composition of the main components differed markedly from that of the analogous components of plasma and depot fat. The findings suggest that the complex lipids of the isolated lipid droplets are synthetized by the renal papilla and probably by the renal interstitial cells. The prostaglandin precursor arachidonic acid constitutes a significant fraction of the triglyceride long-chain fatty acids. Usually also small quantities of prostaglandins were present. Altogether the results suggest that the lipid droplets of the renal interstitial cells may function as a storage site for prostaglandin precursor.This work was supported by a grant from the Danish State Research Foundation. — The authors wish to acknowledge the support and inspiration given by E. Bojesen, M.D., Ph.D., the Institute of Experimental Medicine, Division of Endocrinology. — The authors wish to thank Dr. John E. Pike of the Upjohn Company, Kalamazoo, Michigan, for supplying the Prostaglandins used in this study.     

Two optical coherence tomography systems detect topical gold nanoshells in hair follicles,sweat ducts and measure epidermis

Optical coherence tomography (OCT) is an established imaging technology for in vivo skin investigation. Topical application of gold nanoshells (GNS) provides contrast enhancement in OCT by generating a strong hyperreflective signal from hair follicles and sweat glands, which are the natural skin openings. This study explores the utility of 150 nm diameter GNS as contrast agent for OCT imaging. GNS was massaged into skin and examined in four skin areas of 11 healthy volunteers. A commercial OCT system and a prototype with 3 μm resolution (UHR‐OCT) were employed to detect potential benefits of increased resolution and variability in intensity generated by the GNS. In both OCT‐systems GNS enhanced contrast from hair follicles and sweat ducts. Highest average penetration depth of GNS was in armpit 0.64 mm ± SD 0.17, maximum penetration depth was 1.20 mm in hair follicles and 15 to 40 μm in sweat ducts. Pixel intensity generated from GNS in hair follicles was significantly higher in UHR‐OCT images (P = .002) and epidermal thickness significantly lower 0.14 vs 0.16 mm (P = .027). This study suggests that GNSs are interesting candidates for increasing sensitivity in OCT diagnosis of hair and sweat gland disorders and demonstrates that choice of OCT systems influences results.      

Seroprevalence of <Emphasis Type="Italic">Borrelia burgdorferi</Emphasis> sensu lato and <Emphasis Type="Italic">Anaplasma phagocytophilum</Emphasis> in Danish horses

Background

Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum are able to infect horses. However, the extend to which Danish horses are infected and seroconvert due to these two bacteria is unknown. The aim of the present study was to evaluate the seroprevalence of B. burgdorferi sensu lato and A. phagocytophilum in Danish horses.

Methods

A total of 390 blood samples collected from all major regions of Denmark and with a geographical distribution corresponding to the density of the Danish horse population were analyzed. All samples were examined for the presence of antibodies against B. burgdorferi sensu lato and A. phagocytophilum by the use of the SNAP^®4DX ^® ELISA test.

Results

Overall, 29.0% of the horses were seropositive for B. burgdorferi sensu lato whereas 22.3% were seropositive for A. phagocytophilum.

Conclusions

Antibodies against B burgdorferi sensu lato and A. phagocytophilum are commonly found among Danish horses thus showing that Danish horses are frequently infected by these organisms.

     

Dynamics of human DNA topoisomerases IIalpha and IIbeta in living cells

DNA topoisomerase (topo) II catalyses topological genomic changes essential for many DNA metabolic processes. It is also regarded as a structural component of the nuclear matrix in interphase and the mitotic chromosome scaffold. Mammals have two isoforms (alpha and beta) with similar properties in vitro. Here, we investigated their properties in living and proliferating cells, stably expressing biofluorescent chimera of the human isozymes. Topo IIalpha and IIbeta behaved similarly in interphase but differently in mitosis, where only topo IIalpha was chromosome associated to a major part. During interphase, both isozymes joined in nucleolar reassembly and accumulated in nucleoli, which seemed not to involve catalytic DNA turnover because treatment with teniposide (stabilizing covalent catalytic DNA intermediates of topo II) relocated the bulk of the enzymes from the nucleoli to nucleoplasmic granules. Photobleaching revealed that the entire complement of both isozymes was completely mobile and free to exchange between nuclear subcompartments in interphase. In chromosomes, topo IIalpha was also completely mobile and had a uniform distribution. However, hypotonic cell lysis triggered an axial pattern. These observations suggest that topo II is not an immobile, structural component of the chromosomal scaffold or the interphase karyoskeleton, but rather a dynamic interaction partner of such structures.     

Integration time for short broad band clicks in echolocating FM-bats (Eptesicus fuscus)

Vespertilionid FM-bats (four Eptesicus fuscus and one Vespertilio murinus) were trained in an electronic phantom target simulator to detect synthetic echoes consisting of either one or two clicks. The threshold sound pressure for single clicks was around 47 dB peSPL for all five bats corresponding to a threshold energy of -95 dB re 1 Pa² * s. By varying the interclick interval, T, for double clicks it was shown that the threshold intensity was around — 3 dB relative to the threshold for single clicks at T up to 2.4 ms, indicating perfect power summation of both clicks. A threshold shift of -13.5 dB for a 1 ms train of 20 clicks (0.05 ms interclick interval) confirmed that the bats integrated the power of the stimuli. At T longer than around 2.5 ms the threshold for double clicks was the same as for single clicks. Thus, the bats performed like perfect energy detectors with an integration time of approximately 2.4 ms. This integration time is an order of magnitude shorter than that reported for bats listening passively for pure tones. In our setup the bats emitted sonar signals with durations of 2–3 ms. Hence, the results may indicate that while echolocating the bats integration time is adapted to the duration of the sonar emissions.Abbreviations AGC automatic gain control - FM frequency modulated - peSPL peak equivalent sound pressure level - rms root mean square - SD standard deviation - SE standard error of mean - T interclick interval