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P Weis

Publications and source records attributed to P Weis.

At least 19 recordsLinked to original sources
PubMed2003

Dietary P regulates phosphate transporter expression, phosphatase activity, and effluent P partitioning in trout culture.

Phosphate utilization by fish is an important issue because of its critical roles in fish growth and aquatic environmental pollution. High dietary phosphorus (P) levels typically decrease the efficiency of P utilization, thereby increasing the amount of P excreted as metabolic waste in effluents emanating from rainbow trout aquaculture. In mammals, vitamin D3 is a known regulator of P utilization but in fish, its regulatory role is unclear. Moreover, the effects of dietary P and vitamin D3 on expression of enzymatic and transport systems potentially involved in phosphate utilization are little known. We therefore monitored production of effluent P, levels of plasma vitamin D3 metabolites, as well as expression of phosphatases and the sodium phosphate cotransporter (NaPi2) in trout fed semipu diets that varied in dietary P and vitamin D3 levels. Mean soluble P concentrations varied markedly with dietary P but not with vitamin D3, and constituted 40-70% of total effluent P production by trout. Particulate P concentrations accounted for 25-50% of effluent P production, but did not vary with dietary P or vitamin D3. P in settleable wastes accounted for <10% of effluent P. The stronger effect of dietary P on effluent P levels is paralleled by its striking effects on phosphatases and NaPi2. The mRNA abundance of the intestinal and renal sodium phosphate transporters increased in fish fed low dietary P; vitamin D3 had no effect. Low-P diets reduced plasma phosphate concentrations. Intracellular phytase activity increased but brushborder alkaline phosphatase activity decreased in the intestine, pyloric caeca, and gills of trout fed diets containing low dietary P. Vitamin D3 had no effect on enzyme activities. Moreover, plasma concentrations of 25-hydroxyvitamin D3 and of 1,25-dihydroxyvitamin D3 were unaffected by dietary P and vitamin D3 levels. The major regulator of P metabolism, and ultimately of levels of P in the effluent from trout culture, is dietary P.

6-Phytase↗
PubMed2001

Dinuclear titanium(IV) complexes from amino acid bridged dicatechol ligands: formation, structure, and conformational analysis.

Amino acid bridged dicatechol ligands 3a-e-H4 form dinuclear double-stranded coordination compounds [(3a-e)2Ti2(OCH3)2]2- with titanium(IV) ions. Due to the directionality of the ligands, the chirality of the strand, and the chiral complex units, up to seven isomers, I-VII, can be obtained for the double-stranded complexes of ligands 3a-e-H4. The composition of the mixture of isomeric compounds in solution is strongly dependent on the conditions of complex formation. Under thermodynamic control, only a few isomers are obtained, one of which is the major component of the mixture. X-ray structure analyses were performed for K2[(3b)2Ti2(OH)2] and K2[(3d)2Ti2(OH)2] (type I), and for the meso complex Na2[(3e)(3e')Ti2(OCH3)2]. A conformational analysis that uses Ramachandrans method revealed that the conformation of the amino acids in the ligand strands can be compared with those found for amino acids in helical peptide structures. The most favored isomer of [(3)2Ti2(OCH3)2]2- appears to be of type I, with the catecholamide unit located at the N terminus of the ligand strand that binds to a lambda-configurated titanium(IV) complex unit and the dihydroxybenzyl group at the C terminus that coordinates to a delta-configurated titanium(IV) complex unit. The lambda configuration at the N terminus induces the conformation of a right-handed helix in the amino acid residue, while the delta configuration induces the less favored left-handed helix.

Amino Acids↗
PubMed2001

Calcitermin, a novel antimicrobial peptide isolated from human airway secretions.

The human airways are protected from pathogenic colonization by a blanket of fluid impregnated with innate antimicrobial effector molecules. Among several previously uncharacterized components, we isolated a peptide that had activity primarily targeting Gram-negative bacteria. We named the peptide 'calcitermin' since its amino acid sequence and mass were equivalent to the 15 C-terminal residues of the S100 protein, calgranulin C. The antimicrobial activity of calcitermin was enhanced in acidic buffers (pH 5.4) and in the presence of micromolar concentrations of ZnCl(2). Analysis revealed a putative zinc-binding consensus sequence as well as an alpha-helical conformation in structure-promoting solvents.

Amino Acid Sequence↗
PubMed2001

Lead uptake, distribution, and effects in two dominant salt marsh macrophytes, Spartina alterniflora (cordgrass) and Phragmites australis (common reed).

We examined biomass accumulation, tissue concentrations of lead (Pb), and net uptake of Pb in Phragmites australis (common reed) and Spartina alterniflora (salt cord grass) grown under greenhouse conditions in sediment of different Pb concentrations. Sediment and newly emerged ramets of each plant species were collected in April 1999 from Tuckerton, NJ, a relatively clean salt marsh. One-gallon pots were filled with either control sediment (29 microg g(-1) Pb) or Pb-added sediment (68 microg g(-1) Pb), and the sediment moisture was kept saturated along with controlled additions of additional nutrients. At harvest in October, whole plant biomass was 60-85% greater for pots with P. australis than pots with S. alterniflora and a 40-70% reduction in biomass in response to the addition of Pb was observed for both species. In the high Pb treatments, both concentrations and pools of Pb were greater in the leaves of S. alterniflora than in leaves of P. australis at the end of the growing season. In both species, Pb concentrations were higher in lower leaves than upper leaves. The addition of Pb into experimental pots led to over an 800% increase in Pb standing stock for both species. In S. alterniflora, however, significantly more of this pool was allocated to aboveground biomass (leaves and stems) than to belowground biomass (roots and rhizomes). This difference in allocation was more profound at the higher sediment Pb concentration (Pb-added pots). This fundamental difference between the species in response to Pb contamination indicates that metal export into food webs or the water column should be greater in stands of S. alterniflora than in P. australis. These results suggest that in Pb-contaminated, and possibly all metal-contaminated sediments, the replacement of S. alterniflora with P. australis may reduce metal bioavailability by sequestering a greater proportion of its metal burden in belowground tissues which are likely to be permanently buried.

Biological Availability↗
PubMed1999

Application of the ParaSight-F dipstick test for malaria diagnosis in a district control program.

A rapid test for the diagnosis of Plasmodium falciparum infections based on the detection of histidine-rich-protein II, the ParaSight-F test, was evaluated after introduction in a district malaria control program in Uganda. Suspected treatment failures, pregnant women and infants with clinical malaria and general fever cases were tested at health facilities in malaria hypo-, meso- and holoendemic areas. A total of 1326 tests were carried out by health unit staff, cross read by experienced laboratory staff and results compared with thick film microscopy as the standard. Rater agreement in reading the dipstick result between health unit staff and laboratory staff was high, kappa index 0.94 (0.88-0.99). Sensitivity was 99.6% (99.0-100) for parasite densities above 500/microl, 98.6% (97.7-99.6) for densities above 50/microl and 22.2% (8.6-42.3) for densities below 10/microl. With the applied testing strategies no differences were found between endemicity levels or patient categories. Specificity was 86.2% (83.3-88.8) overall, but significantly higher in general fever cases (92.7%) compared to the other patient groups (84.3%, P=0.009). At the given prevalences positive predictive values (ppv) were above 80% and negative predictive values (npv) above 90% in all cases except in pregnant women (ppv: 77.8%). We conclude that in certain situations this test is an alternative to microscopy to improve diagnostic facilities for case management in malaria control programs in endemic African countries.

Adolescent↗
PubMed1999

Reductions in risk behaviour provide the most consistent explanation for declining HIV-1 prevalence in Uganda.

OBJECTIVE: To monitor the HIV-1 epidemic in Western Uganda and the possible impact of interventions. DESIGN: Results from sentinel surveillance of HIV-1 seroprevalence were compared with cross-sectional serosurvey data and model simulations. METHODS: Age-specific trends in HIV-1 prevalence between 1991 and 1997 amongst antenatal clinic (ANC) attenders in the town of Fort Portal, where a comprehensive AIDS control programme has been implemented since 1991, were analysed. Results were compared with outputs from a mathematical model simulating the HIV-1 epidemic in Uganda. Two scenarios were modelled: one without and one with behaviour change. Sentinel surveillance data were compared with data from a population-based HIV-1 serosurvey at the study site, which was carried out in early 1995. RESULTS: Data from 3271 ANC attenders identified greater education and being single as risk factors for HIV-1 infection. A significant decrease of risk for women with secondary school education over time was observed, whereas the risk for illiterate women remained high. Among women aged 15-19 years (n = 1045) education and marital status-adjusted HIV-1 prevalence declined steadily from 32.2% in 1991 to 10.3% in 1997. For 20-24-year-old women (n = 1010) HIV-1 prevalence increased until 1993 from 19.9% to 31.7% and decreased thereafter (21.7% in 1997). These trends closely follow the prediction of the model simulation assuming behaviour change, and for 1995-1997, confidence intervals of the HIV-1 prevalence estimate exclude the model output for an uninfluenced epidemic. No clear trends of HIV-1 prevalence were found in older women (n = 1216) and comparisons with the model were ambiguous. Sentinel surveillance data at the time of the population survey closely reflected results for the female general population sample for the two younger age-groups (15-19 and 20-24 years). In contrast, pregnant women aged 25-29 years showed significantly lower rates than the population sample (20.8% versus 45.1%). CONCLUSION: HIV-1 prevalence amongst ANC attenders aged 15-24 years can be used to monitor the HIV-1 epidemic in the given setting. Declining trends of HIV-1 prevalence in women aged 15-19 and 20-24 years most likely correspond to a reduced HIV-1 incidence attributable to changes in behaviour. Our data also show that sentinel surveillance data need to be age-stratified to give useful information.

Adolescent↗
PubMed1999

Sexually transmitted infections in young pregnant women in Bangui, Central African Republic.

In early 1996, 481 women visiting the antenatal services of the 3 major governmental health centres in the capital city of the Central African Republic (CAR) were included in the study. All study participants underwent the health centre's routine gynaecological examination, including laboratory diagnosis of trichomoniasis, candidiasis, gonorrhoea, syphilis and bacterial vaginosis. Cervical secretions and blood samples from study participants were sent to the National STD Reference Centre for diagnosis of Chlamydia trachomatis, Neisseria gonorrhoeae, Candida albicans, Treponema pallidum, and HIV. Overall, 34% of the study women were diagnosed with at least one sexually transmitted infection (STI) (3.1% N. gonorrhoeae, 6.2% C. trachomatis, 9.9% T. vaginalis, 6.7% T. pallidum, 12.2% HIV-1). In addition, 29.1% of women were diagnosed with bacterial vaginosis and 46.6% with candidiasis. Only a small proportion of these women had sought treatment during the weeks before, despite the recognition of genital symptoms. Self-reported and health worker-recognized symptoms, signs and laboratory results exhibited only low sensitivities, specificities, and positive predictive values in the diagnosis of STIs. These findings confirm the high vulnerability of young African women to STIs and emphasize the need for specific control interventions which should include affordable and user-friendly services. Moreover, these results call for more effective quality control in case of laboratory-based STI control strategies and question the validity of syndromic STI management strategies in women attending antenatal care services in Africa.

Adolescent↗
PubMed1998

The Extent of Benthic Impacts of CCA-Treated Wood Structures in Atlantic Coast Estuaries

To ascertain the extent of impacts from CCA-treated wood bulkheads, we sampled sediments along 10-m transects from these bulkheads and from reference sites (either bulkheads made of other materials or unbulkheaded areas nearby) and analyzed the fine fraction for metals. We ascertained metal content in resident biota, and analyzed species richness, Shannon-Wiener diversity index, and biomass of the benthic community. We found accumulation of metals in the fine-grained portion of nearby sediments and reduction in the biotic community nearby (generally at 0 and 1 m); such gradients were generally not seen in reference transects. At two of the sites there was evidence for secondary reduction of the community out further to 3 or 10 m, where the metals in the fines were lower but the percent fines was greatly increased. At all the other sites, impacts were generally limited to 0 and 1 m. The lack of reduction at further distances at the other sites is attributed to factors such as the age of the bulkheads, high energy of the environment, or nature of the sediments at those sites.

Journal Article↗
PubMed1998

Ivermectin distribution using community volunteers in Kabarole district, Uganda.

Ivermectin mass distribution for the control of onchocerciasis in Uganda began in 1991. This report describes a community based ivermectin distribution programme covering two foci in the Kabarole district which have an estimated 32,000 persons infected and another 110,000 at risk. Through nodule palpation in adult males, 143 villages were identified where nodule prevalence exceeded 20%. Skin snips were also taken from a sample of the population to measure changes in community microfilarial load (CMFL) with treatment. The delivery programme was integrated into the district health management structure, and used community volunteers supervised by medical assistants from adjacent health facilities for annual ivermectin distribution campaigns. After initial efforts by the community to support distributors in-kind proved inadequate, ivermectin distributors earned money retailing condoms as part of the social marketing component of district STD/AIDS programme. Reduction in the CMFL ranged from 40-62% twelve months after the second ivermectin treatment in three villages, and from 69-84% six months after the fourth round of treatment in two villages. After four years of treatment, 85% of eligible persons were receiving ivermectin from community volunteers in each treatment cycle. Drop out rates among volunteers did not exceed 20% over the four years reported here. The direct cost of treatment was US $0.29 per person. Among the reasons for low per-person treatment costs were the strong supervisory structure, the presence of health centres in the foci and a well developed and capable district Primary Health Care management team.

Adult↗
PubMed1997

Isolation and characterization of pleurocidin, an antimicrobial peptide in the skin secretions of winter flounder.

Antimicrobial peptides are found in both myeloid cells and mucosal tissues of many vertebrates and invertebrates. These peptides are predicted to operate as a first-line host defense mechanism exerting broad-spectrum activity against pathogenic bacteria, fungi, parasites, and enveloped viruses. We report the characterization of a novel 25-residue linear antimicrobial peptide found in the skin mucous secretions of the winter flounder (Pleuronectes americanus). This peptide was purified through multiple chromatographic methods to obtain a single peak by reversed-phase high performance liquid chromatography. This purified peptide, which we named pleurocidin, exhibited antimicrobial activity against Escherichia coli in a bacterial cell lysis plate assay. Mass spectrometry and amino acid sequence analysis indicated that it is 25 amino acids in length. Pleurocidin is predicted to assume an amphipathic alpha-helical conformation similar to many other linear antimicrobial peptides. There is a high degree of homology between pleurocidin and two antimicrobial peptides, ceratotoxin from the Mediterranean fruit fly and dermaseptin from the skin of a hylid frog. The minimal inhibitory concentration and minimal bactericidal concentration of pleurocidin were determined against 11 different Gram-negative and Gram-positive bacteria. Immunohistochemistry locates pleurocidin in the epithelial mucous cells of flounder skin. Pleurocidin represents a novel antimicrobial peptide found in fish and may play a role in innate host defense.

Amino Acid Sequence↗
PubMed1992

Toxicity of construction materials in the marine environment: a comparison of chromated-copper-arsenate-treated wood and recycled plastic.

Previous studies have demonstrated leaching from chromated-copper-arsenate (CCA)-treated wood, which is used in pilings and bulkheads, and resulting toxicity to various estuarine organisms. The current study compared effects of leachates from CCA-treated wood with those of recycled plastic "lumber," a possible alternative construction material. Limb regeneration in fiddler crabs, while depressed in leachates from CCA wood, was accelerated in three formulations of recycled plastics. The acceleration was reduced in subsequent trials with the same pieces of plastic. Using a sea urchin fertilization test, no effects were seen in 1- and 3-day leachates from the plastics. However, CCA wood reduced fertilization by 90%, and totally inhibited larval development of those that did fertilize. A smaller piece of wood, one-tenth the size (0.4 cm2), did not have a significant effect on fertilization or development. With 1-3 weeks of leaching, significant reductions in fertilization were seen in sea urchin gametes exposed to one plastic formulation and no fertilization was seen in leachates from the small piece of CCA wood. Two formulations enriched to 30% polystyrene (PS) had no significant effect on fertilization, but did reduce larval growth. When the same pieces of plastic and wood were used for a second set of experiments, all three formulations of plastic, as well as the small piece of wood, inhibited fertilization significantly, and one of the 30% PS formulations and the wood caused reduced larval growth. In another assay, snails and an alga were exposed to plastics for two months with no observed effect; the CCA leachates caused 100% snail mortality within one week and chlorosis of the alga.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Toxicity to estuarine organisms of leachates from chromated copper arsenate treated wood.

The effects of chromated copper arsenate (CCA), used for treating wood in docks, pilings, and bulkheads, were studied in several estuarine organisms. Leaching of metals from treated wood into sea water was assayed by atomic absorption spectrophotometry. Fiddler crabs (Uca pugilator) were subjected to limb removal and were placed in containers with treated wood of various sizes or control wood. Limb regeneration rate was retarded in a dose-dependent fashion and mortality occurred with the treated wood, reaching 100% in the tank with the largest piece of wood. Embryos of the mummichog (Fundulus heteroclitus) were allowed to develop in culture dishes in which CCA-treated or untreated wood was soaking. Mortality was noted in the dishes with treated wood and to a smaller extent in those with untreated wood. Containers containing CCA-treated wood, control wood, or no wood were stocked first with the alga Ulva lactuca, the snails (Nassarius obsoletus). Chlorophyll content of the algae was reduced with the treated wood within a few days, and snails with the treated wood became moribund and died within a few days. In the controls containing untreated wood or no wood, no such effects were seen. Studies with individual or combination of two or three of the metals with snails and algae indicated that the copper was primarily responsible for the snail mortality and algal bleaching seen in the treated wood experiments. In all experiments, the toxicity of the wood decreased over time; when the experiments were repeated with the same pieces of wood, effects were diminished.

Animals↗