Observation of Seven Astrophysical Tau Neutrino Candidates with IceCube.

We report on a measurement of astrophysical tau neutrinos with 9.7 yr of IceCube data. Using convolutional neural networks trained on images derived from simulated events, seven candidate ν_{τ} events were found with visible energies ranging from roughly 20 TeV to 1 PeV and a median expected parent ν_{τ} energy of about 200 TeV. Considering backgrounds from astrophysical and atmospheric neutrinos, and muons from π^{±}/K^{±} decays in atmospheric air showers, we obtain a total estimated background of about 0.5 events, dominated by non-ν_{τ} astrophysical neutrinos. Thus, we rule out the absence of astrophysical ν_{τ} at the 5σ level. The measured astrophysical ν_{τ} flux is consistent with expectations based on previously published IceCube astrophysical neutrino flux measurements and neutrino oscillations.

Cellular Organization and Regulation of Plant Glycerolipid Metabolism.

Great strides have been made in understanding how membranes and lipid droplets are formed and maintained in land plants, yet much more is to be learned given the complexity of plant lipid metabolism. A complicating factor is the multi-organellar presence of biosynthetic enzymes and unique compositional requirements of different membrane systems. This necessitates a rich network of transporters and transport mechanisms that supply fatty acids, membrane lipids and storage lipids to their final cellular destination. Though we know a large number of the biosynthetic enzymes involved in lipid biosynthesis and a few transport proteins, the regulatory mechanisms, in particular, coordinating expression and/or activity of the majority remain yet to be described. Plants undergoing stress alter their membranes' compositions, and lipids such as phosphatidic acid have been implicated in stress signaling. Additionally, lipid metabolism in chloroplasts supplies precursors for jasmonic acid (JA) biosynthesis, and perturbations in lipid homeostasis has consequences on JA signaling. In this review, several aspects of plant lipid metabolism are discussed that are currently under investigation: cellular transport of lipids, regulation of lipid biosynthesis, roles of lipids in stress signaling, and lastly the structural and oligomeric states of lipid enzymes.

Arabidopsis galactolipid biosynthesis and lipid trafficking mediated by DGD1.

The photosynthetic apparatus in plant cells is associated with membranes of the thylakoids within the chloroplast and is embedded into a highly specialized lipid matrix. Diacylglycerol galactolipids are common in thylakoid membranes but are excluded from all others. Isolation of the gene DGD1, encoding a galactosyltransferase-like protein, now provides insights into assembly of the thylakoid lipid matrix and subcellular lipid trafficking in Arabidopsis thaliana.

Unraveling plant metabolism by EST analysis.

Large-scale single-pass sequencing of cDNAs prepared from specific plant species or tissues has evolved as an inexpensive and efficient gene-discovery tool that can be used to identify novel cDNAs encoding enzymes of specific plant metabolic pathways. Collections of expressed sequence tags from metabolically active tissues can provide quantitative estimates of gene expression levels and thus are being exploited to unravel plant metabolic and regulatory networks.

Suppression of human prostate cancer cell growth by alpha1-adrenoceptor antagonists doxazosin and terazosin via induction of apoptosis.

Recent evidence from our laboratory has demonstrated that alpha1-adrenoceptor antagonists doxazosin and terazosin induced apoptosis in prostate epithelial and smooth muscle cells in patients with benign prostatic hypertrophy (BPH; J. Urol., 159: 1810-1815, 1998; J. Urol., 161: 2002-2007, 1999). In this study, we investigated the biological action of three alpha1-adrenoceptor antagonists, doxazosin, terazosin, and tamsulosin, against prostate cancer cell growth. The antigrowth effect of the three alpha1-adrenoceptor antagonists was examined in two human prostate cancer cell lines, PC-3 and DU-145, and a prostate smooth muscle cell primary culture, SMC-1, on the basis of: (a) cell viability assay; (b) rate of DNA synthesis; and (c) induction of apoptosis. Our results indicate that treatment of prostate cancer cells with doxazosin or terazosin results in a significant loss of cell viability, via induction of apoptosis in a dose-dependent manner, whereas tamsulosin had no effect on prostate cell growth. Neither doxazosin nor terazosin exerted a significant effect on the rate of cell proliferation in prostate cancer cells. Exposure to phenoxybenzamine, an irreversible inhibitor of alpha1-adrenoceptors, does not abrogate the apoptotic effect of doxazosin or terazosin against human prostate cancer or smooth muscle cells. This suggests that the apoptotic activity of doxazosin and terazosin against prostate cells is independent of their capacity to antagonize alpha1-adrenoceptors. Furthermore, an in vivo efficacy trial demonstrated that doxazosin administration (at tolerated pharmacologically relevant doses) in SCID mice bearing PC-3 prostate cancer xenografts resulted in a significant inhibition of tumor growth. These findings demonstrate the ability of doxazosin and terazosin (but not tamsulosin) to suppress prostate cancer cell growth in vitro and in vivo by inducing apoptosis without affecting cell proliferation. This evidence provides the rationale for targeting both drugs, already in clinical use and with established adverse-effect profiles, against prostatic tumors for the treatment of advanced prostate cancer.

Immunohistochemical localization of parathyroid hormone-related protein in human prostate cancer.

Parathyroid hormone-related protein (PTHrP) is produced by a variety of malignant tumors and has been implicated as a major cause of humoral hypercalcemia of malignancy. Expression of PTHrP in prostate cancer tissue was studied immunohistochemically using 33 radical prostatectomy specimens from patients with clinically localized carcinoma of the prostate. None of these patients demonstrated hypercalcemia prior to the surgery. Acetone-methyl benzoate-xylene-processed, paraffin-embedded tissues were stained with a validated mouse monoclonal antibody to an amino acid fragment, PTHrP(109-141), using the streptavidin-peroxidase enzyme conjugate method. All cases (33 of 33; 100%) studied demonstrated some degree of immunoreactivity throughout the cytoplasm of the tumor cells, but immunostaining was absent from inflammatory and stromal cells. The intensity of the staining appeared to directly correlate with increasing tumor grade. The widespread immunohistochemical localization of PTHrP in carcinoma of the prostate suggests that PTHrP may play some local role in the growth of transformed cells in the prostate. Furthermore, overexpression of PTHrP may be a possible marker to evaluate the malignant potential of carcinoma of the prostate.

The phospholipid-deficient pho1 mutant of Arabidopsis thaliana is affected in the organization, but not in the light acclimation, of the thylakoid membrane.

The pho1 mutant of Arabidopsis has been shown to respond to the phosphate deficiency in the leaves by decreasing the amount of phosphatidylglycerol (PG). PG is thought to be of crucial importance for the organization and function of the thylakoid membrane. This prompted us to ask what the consequences of the PG deficiency may be in the pho1 mutant when grown under low or high light. While in the wild-type, the lipid pattern was almost insensitive to changes in the growth light, PG was reduced to 45% under low light in the mutant, and it decreased further to 35% under high light. Concomitantly, sulfoquinovosyl diacylglycerol (SQDG) and to a lesser extent digalactosyl diacylglycerol (DGDG) increased. The SQDG increase correlated with increased amounts of the SQD1 protein, an indicator for an actively mediated process. Despite of alterations in the ultrastructure, mutant thylakoids showed virtually no effects on photosynthetic electron transfer, O2 evolution and excitation energy allocation to the reaction centers. Our results support the idea that PG deficiency can at least partially be compensated for by the anionic lipid SQDG and the not charged lipid DGDG. This seems to be an important strategy to maintain an optimal thylakoid lipid milieu for vital processes, such as photosynthesis, under a restricted phosphate availability.

Disruption of a gene essential for sulfoquinovosyldiacylglycerol biosynthesis in Sinorhizobium meliloti has no detectable effect on root nodule symbiosis.

The sulfolipid sulfoquinovosyldiacylglycerol is commonly found in the thylakoid membranes of photosynthetic bacteria and plants. While there is a good correlation between the occurrence of sulfolipid and photosynthesis, a number of exceptions are known. Most recently, sulfoquinovosyldiacylglycerol was discovered in the non-photosynthetic, root nodule-forming bacterium Sinorhizobium meliloti. This discovery raised the questions of the phylogenetic origin of genes essential for the biosynthesis of this lipid in S. meliloti and of a function of sulfolipid in root nodule symbiosis. To begin to answer these questions, we isolated and inactivated the sqdB gene of S. meliloti. This gene and two other genes located directly 3' of sqdB are highly similar to the sqdB, sqdC, and sqdD genes known to be essential for sulfolipid biosynthesis in the photosynthetic, purple bacterium Rhodobacter sphaeroides. This observation confirms the close phylogenetic kinship between these two species. Furthermore, the reduced similarity of sqdB to the plant ortholog SQD1 of Arabidopsis thaliana does not support a previous sqd gene transfer from the plant as a consequence of close symbiosis. A sulfolipid-deficient mutant of S. meliloti disrupted in sqdB is capable of inducing functional nodules and does not show an obvious disadvantage under different laboratory culture conditions. Thus far, no specific function can be assigned to bacterial sulfolipid, in either nodule-associated or free-living cells. S. meliloti contains a rich set of polar membrane lipids some of which, including sulfolipid, may become critical only under growth conditions that still need to be discovered.

Androgen receptor immunostaining and its tissue distribution in formalin-fixed, paraffin-embedded sections after microwave treatment.

We used microwave (MW) oven heat treatment to unmask human androgen receptor (AR) immunostaining in formalin-fixed, paraffin-embedded tissue. Prostate tissue was used as an AR-positive control. Tissue sections were boiled in citrate buffer in a conventional MW oven for 30 min, followed by immunostaining with a validated murine monoclonal antibody (MAb), F39.4.1, raised against a peptide included in the N-terminal domain of the 100 KD human AR. AR immunostaining was localized to the nuclei of prostate secretory epithelial cells but was weak or absent in basal cells and of variable intensity in the stromal cells. Slides exposed to less than 10 min of MW heat treatment or none at all manifested no AR immunoreactivity. Tissue morphology was well preserved. Immunohistochemical determination of AR status in a wide variety of human tissues was consistent with that previously reported by others using frozen sections. MW heat treatment of tissue samples in an excellent method of localizing AR antigenicity, enabling immunohistochemical evaluation of AR status in formalin-fixed, paraffin-embedded material.

Overexpression of human epidermal growth factor receptor and c-erbB-2 by neuroendocrine cells in normal prostatic tissue.

OBJECTIVE: It has been suggested that prostatic neuroendocrine (NE) cells play an important role in the growth and differentiation of the prostate by secreting various neuropeptides and serotonin. However, the mechanism by which NE cells themselves are regulated is virtually unknown. In the present study we evaluated the expression of the human epidermal growth factor receptor (EGFR) family (HER) in prostatic NE cells. METHODS: Formalin-fixed, paraffin-embedded tissue sections from twenty radical prostatectomy specimens were immunostained with validated rabbit polyclonal antibodies raised against human EGFR and c-erbB-2, using the streptavidin-peroxidase enzyme conjugate method. RESULTS: A strong immunoreactivity was observed with both antibodies in the cytosol of a few epithelial cells. These cells frequently had a dendritic appearance and were located in the acini and ducts. The EGFR-positive cells were predominant in most cases. Double immunostaining revealed the colocalization of both antigens with chromogranin A, a polypeptide that is expressed by most NE cells. Moreover, EGFR and c-erbB-2 appeared to be colocalized as well as independently expressed by different subpopulations of NE cells. CONCLUSIONS: The results suggest that prostatic NE cells might be regulated by the HER protein family, probably, in a ligand-specific fashion. This is the first report identifying a potential pathway regulating prostatic NE cells.

Galactolipids not associated with the photosynthetic apparatus in phosphate-deprived plants.

The galactolipid digalactosyldiacylglycerol (DGGD) is one of the major constituents of thylakoids, accounting for about 25% of polar lipids found in these membranes. Although the presence of DGDG has frequently been correlated with the structural and functional integrity of the photosynthetic apparatus, it is still a matter of debate of what the in-vivo function of DGDG actually might be. To further the understanding of the role of DGDG within the photosynthetic apparatus, experiments were conducted on different Arabidopsis thaliana lines with altered DGDG content. The dgd1 mutant is characterized by a 90% reduction in the DGDG content, resulting in a severe dwarfism during growth. Complementation of the dgd1 mutant with a DGD1 cDNA completely restored the wild-type characteristics, while photosynthesis-related parameters were intermediate in transgenic plants with a partial reduction in DGD1 activity caused by post-transcription gene silencing due to over-expression of a DGD1 cDNA in wild-type plants. These data provide clear evidence for a causal relationship between the DGDG content, and the structure and function of the photosynthetic apparatus. However, a significant DGDG accumulation in the dgd1/pho1 double mutant was without any detectable effect on photosynthetic activity, indicating that the molecular DGDG species synthesized upon phosphate deprivation in leaves cannot substitute for the DGDG species present under normal nutrient supply of plants. It is suggested that depending on the environmental growth conditions different pools of DGDG species exist in plants of which one is not associated with the photosynthetic apparatus.

Comparison of sulfoquinovosyl diacylglycerol from spinach and the purple bacterium Rhodobacter spaeroides by fast atom bombardment tandem mass spectrometry.

Isolated sulfoquinovosyl-diacylglycerol (SQD) from spinach and the purple bacterium Rhodobacter sphaeroides provide two sources of very different molecular species of SQD. We were able to demonstrate by fast atom bombardment-collisionally activated dissociation tandem mass spectrometry in the negative ion mode that the sulfoquinovosyl head group of the plant and bacterial lipids can be characterized by the common fragmentation pattern found in the spectra of both samples. Differences in the acyl functions from the two sources were also identified by this technique. SQD specific fragments are found at m/z 299, 283, 241, 225, 165 and 80 which indicate the presence of the sulfoquinovosyl moiety. The two predominant molecular species found in spinach contain palmitic and linolenic ([M-H]- at m/z 815) or two linolenic acids ([M-H]- at m/z 837) in the sn-1 and sn-2 positions, while the two major species of the bacterial lipid contain palmitic and 18:1 (vaccenic) acids ([M-H]- at m/z 819) or stearic and 18:1 (vaccenic) acids, ([M-H]- at m/z 847), respectively.

[A study of damaged acoustic biopotentials in guinea pigs following exposure to white noise]. / Das verhalten akustisch vorgeschädigter biopotentiale beim meerschweinchen nach beschallung mit weissem rauschen

62 guinea-pigs were treated twice exposed to white noise, 105 dB SPL, 20 to 20 000 cps for 40 minutes with a break of 24 hours in between. The cochlear microphonics (CM), the compound action potentials of the acoustic nerve (NAP) and the slow evoked potentials (SEP) were recorded. There were different degrees of damage to be seen in the acoustic biopotentials. The CM showed little damages only whereas the compound action potentials of the hearing nerve showed significant impairments in excitation and in adaptation. In the SEP excitation was decreased. From this, we may conclude that the CM must not be the only criterion for judging damages in the acoustic system after acoustic trauma. Furthermore we see that the central acoustic pathway is capable to compensate peripheric hearing damages within a short time. An additional exposure to noise does not necessarily add or cumulate the degrees of damage.

Psychosocial needs of family members of liver transplant patients.

Recent literature is beginning to reflect the importance of psychosocial needs of liver transplant patients, examining functional outcome, quality of life, daily living, and psychiatric and neurocognitive outcome. Little attention has been paid to the psychosocial needs of the liver transplant patient's family or significant other. Family members, along with the patient, must cope with disease chronicity, an uncertain organ donor waiting period, role reversal, a protracted postoperative hospital course, and a complicated medical regimen after discharge. Consequently, demands on time, energy, finances, and relationships can strain an already stressed family structure. Psychosocial needs of the liver transplant patient's family are discussed in this article, including aspects of chronic disease, the transplant evaluation, the waiting period, the immediate postoperative period, and long-term adjustment and recovery. Nursing interventions to facilitate effective coping strategies are suggested. Gaps in the existing literature are identified and suggestions for future research are made.

Lipid trafficking between the endoplasmic reticulum and the chloroplast.

The photosynthetic (thylakoid) membrane of plants is one of the most extensive biological cell membrane systems found in Nature. It harbours the photosynthetic apparatus, which is essential to life on Earth as carbon dioxide is fixed and atmospheric oxygen released by photosynthesis. Lipid biosynthetic enzymes of different subcellular compartments participate in the biogenesis of the thylakoid membrane system. This process requires the extensive exchange of lipid precursors between the chloroplast and the ER (endoplasmic reticulum). The underlying lipid trafficking phenomena are not yet understood at the mechanistic level, but genetic mutants of the model plant Arabidopsis thaliana with disruptions in lipid trafficking between the ER and the chloroplast have recently become available. Their study has led to the identification of components of the lipid transfer machinery at the inner chloroplast envelope.

Evidence supporting a model of voltage-dependent uptake of auxin into Cucurbita vesicles.

The accumulation of [(14)C]indole-3-acetic acid (IAA), of [(3)H]tetra-phenyl phosphonium ion as a membrane potential probe, and of [(14)C]butyric acid as probe for pH gradients was studied with membrane vesicles from etiolated hypocotyls of Cucurbita pepo. Ion gradients (K(+), H(+)) were applied in the presence and absence of specific ionophores e.g. valinomycin or carbonylcyanide m-chlorophenylhydrazone. In all cases tested, the accumulation of [(14)C]IAA equals neither potential probe nor pH-probe accumulation, but represents. an intermediate between the two. Auxin molecules seem to be taken up as positively charged ions and a pH gradient is required for accumulation. The uptake mechanism thus appears to be a specific, carrier-mediated cotransport of the anion of IAA and no less than two protons. The initial rates of auxin uptake by the saturable influx carrier, of permeation through the membrane, and of efflux by the phytotropin-affected efflux carrier were analysed.

Can digalactosyldiacylglycerol substitute for phosphatidylcholine upon phosphate deprivation in leaves and roots of Arabidopsis?

To explore the role of digalactosyldiacylglycerol (DGDG) in plants the dgd1 mutant of Arabidopsis thaliana was grown in the presence and absence of inorganic phosphate. Phosphate deficiency in the dgd1 mutant causes a strong decrease in all phospholipids accompanied by an increase in DGDG and sulpholipid. Moreover, a significant DGDG accumulation was found in roots upon phosphate deprivation as well. Our data indicate that DGDG accumulation upon phosphate deprivation is due to the activation of a specific eukaryotic dgd1-independent biosynthetic pathway. We propose that DGDG may substitute for phosphatidylcholine upon phosphate deprivation.

Functional expression of uridine 5'-diphospho-glucose 4-epimerase (EC 5.1.3.2) from Arabidopsis thaliana in Saccharomyces cerevisiae and Escherichia coli.

It is our goal to investigate the biosynthesis of galactose-containing compounds in higher plants. Searching a database of expressed sequence tags, a cDNA from Arabidopsis thaliana (clone 108G20T7) with sequence similarity to UDP-glucose epimerase was identified and further analyzed. The 1356-bp-long cDNA included an open reading frame predicted to encode a 351 amino acid protein of 39 kDa. The presumed protein sequence showed a high degree of similarity to UDP-glucose epimerase sequences from bacteria, rat, and yeast. Complementation of the Saccharomyces cerevisiae gal1O mutant and expression of an active enzyme in Escherichia coli demonstrated that the cDNA encoded a functional UDP-glucose epimerase. The recombinant enzyme was purified to homogeneity. It showed a broad pH optimum of 7.0 to 9.5 and a Km of 0.11 mM. The UDP-glucose epimerase activity was not dependent on the addition of the cofactor NAD+ and was only moderately inhibited by high salt concentrations. Tissue-specific Northern analysis showed that the gene is expressed in all tissues of A. thaliana with highest expression levels in the stems and roots. Based on Southern analysis, there seems to be a single gene encoding UDP-glucose epimerase in A. thaliana. The cDNA analyzed during this study is the first known to encode a sugar-nucleotide modifying enzyme from higher plants. Its availability provides the means to investigate the role of UDP-glucose epimerase for the biosynthesis of UDP-galactose as precursor of galactolipids and cell wall polysaccharides.