Spatial and temporal patterns of carabid activity-density in cereals do not explain levels of predation on weed seeds.

Seed predation is an important component of seed mortality of weeds in agro-ecosystems, but the agronomic use and management of this natural weed suppression is hampered by a lack of insight in the underlying ecological processes. In this paper, we investigate whether and how spatial and temporal variation in activity-density of granivorous ground beetles (Coleoptera: Carabidae) results in a corresponding pattern of seed predation. Activity-density of carabids was measured by using pitfall traps in two organic winter wheat fields from March to July 2004. Predation of seeds (Capsella bursa-pastoris, Lamium amplexicaule, Poa annua and Stellaria media) was assessed using seed cards at the same sites and times. As measured by pitfall traps, carabids were the dominant group of insects that had access to the seed cards. In the field, predation of the four different species of seed was in the order: C. bursa-pastoris>P. annua>S. media>L. amplexicaule; and this order of preference was confirmed in the laboratory using the dominant species of carabid. On average, seed predation was higher in the field interior compared to the edge, whereas catches of carabids were highest near the edge. Weeks with elevated seed predation did not concur with high activity-density of carabids. Thus, patterns of spatial and temporal variation in seed predation were not matched by similar patterns in the abundance of granivorous carabid beetles. The lack of correspondence is ascribed to effects of confounding factors, such as weather, the background density of seeds, the composition of the carabid community, and the phenology and physiological state of the beetles. Our results show that differences in seed loss among weed species may be predicted from laboratory trials on preference. However, predator activity-density, as measured in pitfall traps, is an insufficient predictor of seed predation over time and space within a field.

Management considerations for organic waste use in agriculture.

Organic wastes are utilized in agriculture mainly for improving the soil physical and chemical properties and for nutrient sources for growing crops. The major source of organic waste used in agriculture is animal manure, but small amounts of food processing and other industrial wastes (along with municipal wastes) are also applied to land. In the last 35 years, and especially in the last 10 years, there have been increasing environmental regulations affecting farms that have resulted in more animal manure treatment options, and thus affecting characteristics of residues that are subsequently applied to land. Farms are being assessed for nutrient balances, with the entire nutrient and manure management system evaluated for best management alternatives. Because of inadequate available land on the animal farm in some cases, organic wastes must be treated and/or transported to other farms, or utilized for horticultural or other uses. This paper discusses the various factors and challenges for utilizing organic wastes in agriculture.

Determination of membrane immersion depth with O(2): a high-pressure (19)F NMR study.

Oxygen is known to partition with an increasing concentration gradient toward the hydrophobic membrane interior. At partial pressures (P(O2)) of 100 Atm or more, this concentration gradient is sufficient to induce paramagnetic effects that depend sensitively on membrane immersion depth. This effect is demonstrated for the fluorine nucleus by depth-dependent paramagnetic shifts and spin-lattice relaxation rates, using a fluorinated detergent, CF3(CF(2))(5)C(2)H(4)-O-maltose (TFOM), reconstituted into a lipid bilayer model membrane system. To interpret the spin-lattice relaxation rates (R) in terms of a precise immersion depth, two specifically fluorinated cholesterol species (6-fluorocholesterol and 25-fluorocholesterol), whose membrane immersion depths were independently estimated, were studied by (19)F NMR. The paramagnetic relaxation rates, R, of the cholesterol species were then used to parameterize a Gaussian profile that directly relates R to immersion depth z. This same Gaussian curve could then be used to determine the membrane immersion depth of all six fluorinated chain positions of TFOM and of two adjacent residues of specifically fluorinated analogs of the antibacterial peptide indolicidin. The potential of this method for determination of immersion depth and topology of membrane proteins is discussed.

Using O2 to probe membrane immersion depth by 19F NMR.

A fluorinated detergent, CF(3)(CF(2))(5)C(2)H(4)-O-maltose, was reconstituted into a lipid bilayer model membrane system to demonstrate the feasibility of determining solvent accessibility and membrane immersion depth of each fluorinated group by (19)F NMR. Apolar oxygen, which is known to partition with an increasing concentration gradient toward the hydrophobic membrane interior, exhibits a range of paramagnetic relaxation effects on (19)F nuclei, depending on its depth in the membrane. This effect, which is predominately associated with spin-lattice relaxation rates (R(1)) and chemical shifts, can be amplified greatly with minimal line broadening by increasing the partial pressure of O(2) at least 100-fold (i.e., P(O(2)) greater than 20 bar). The differences of longitudinal relaxation rates at 20 bar of oxygen pressure to those under ambient pressure (R(1)(20bar) - R(1)(0)) are largest for those fluorine groups expected to be most deeply buried in the membrane bilayer. This result contrasts with the reverse trend, which is observed on addition of a membrane surface-associated paramagnetic species, 4-(N,N-dimethyl-N-hexadecyl) ammonium-2,2,6,6-tetramethylpiperidine-1-oxyl iodide (CAT-16) at ambient pressures. Thus, differential relaxation rates may be observed in (19)F-labeled membrane-associated molecules resulting from the addition of apolar oxygen under high pressure. The results demonstrate that the degree of solvent accessibility and membrane immersion depth of specific fluorinated species in membrane-associated macromolecules can be probed by (19)F NMR.

Fluorocholesterols, in contrast to hydroxycholesterols, exhibit interfacial properties similar to cholesterol.

We used an automated Langmuir-Pockels surface balance to characterize the air-water interfacial properties of cholesterol (CH) and its derivatives with hydrophilic OH and F substitutions at isologous sites on the sterol body or side chain. We studied 6-fluorocholesterol, 25-fluorocholesterol, 25,26,26,26,27,27,27-heptafluorocholesterol, 7alpha-hydroxycholesterol, 7beta-hydroxycholesterol, 25-hydroxycholesterol and 27-hydroxycholesterol, alone and in mixtures with 1-palmitoyl-2-oleoyl-sn-3-glycero-phosphocholine (POPC). Pressure;-area isotherms of the fluorocholesterols were essentially indistinguishable from CH and all condensed POPC monomolecular layers (monolayers) to variable degrees. Both nucleus-substituted hydroxycholesterols formed expanded monolayers, with lift-offs from baseline 22-26 A(2)/molecule larger than CH, suggesting interfacial tilting; furthermore, in binary mixtures, they condensed POPC monolayers less than CH. In contrast, the side chain hydroxylated CHs were oriented horizontally in the interface at large molecular areas, and became vertical below 140 A(2)/molecule with the side chain-OH rather than 3-OH group anchored in the subphase, as evidenced by low collapse pressures and smaller molecular areas than CH. Both side chain hydroxycholesterols expanded POPC monolayers at molar ratios <30%, but induced condensation with higher ratios, suggesting that OH-acyl chain (POPC) repulsion is superceded at higher mole fractions by lateral phase separation and intersteroidal H-bonding. These studies predict that fluorocholesterols should exhibit intramembrane spatial occupancy nearly identical to CH, whereas nucleus and especially side chain hydroxycholesterols will perturb membrane lipid packing notably.

Long circulating half-life and high tumor selectivity of the photosensitizer meta-tetrahydroxyphenylchlorin conjugated to polyethylene glycol in nude mice grafted with a human colon carcinoma.

In a mode of nude mice bearing a human colon carcinoma xenograft, the biodistribution and tumor localization of metatetrahydroxyphenylchlorin (m-THPC) coupled to polyethylene glycol (PEG) were compared with those of the free form of this photosensitizer used in photodynamic therapy (PDT). At different times after i.v. injection of both forms of 125I-labeled photosensitizer, m-THPC-PEG gave on average a 2-fold higher tumor uptake than free m-THPC. In addition, at early times after injection, m-THPC-PEG showed a 2-fold longer blood circulating half-life and a 4-fold lower liver uptake than free m-THPC. The tumor to normal tissue ratios of radioactivity concentrations were always higher for m-THPC-PEG than for free m-THPC at any time point studied from 2 to 96 hr post-injection. Significant coefficients of correlation between direct fluorescence measurements and radioactivity counting were obtained within each organ tested. Fluorescence microscopy studies showed that m-THPC-PEG was preferentially localized near the tumor vessels, whereas m-THPC was more diffusely distributed inside the tumor tissue. To verify whether m-THPC-PEG conjugate remained phototoxic in vivo, PDT experiments were performed 72 hr after injection and showed that m-THPC-PEG was as potent as free m-THPC in the induction of tumor regression provided that the irradiation does for m-THPC-PEG conjugate was adapted to a well-tolerated 2-fold higher level. The overall results demonstrate first the possibility of improving the in vivo tumor localization of a hydrophobic dye used for PDT by coupling it to PEG and second that a photosensitizer conjugated to a macromolecule can remain phototoxic in vivo.

Anomalous phase transition in dipalmitoylphosphatidylethanolamine/palmitoylphosphatidylcholine/water system.

An anomalous phase transition with a marked rise in specific heat, the isobaric thermal expansion coefficient, and the compressibility coefficient at 62.5 degrees C for an equimolar mixture of 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) and 1-palmitoyl-sn-glycero-3-phosphocholine (PLPC), in water (34 wt.%) has been shown by differential scanning calorimetry, scanning dilatometry and isothermal compressibility measurements. This transition occurs 15 degrees C above a first-order transition observed in the same system. (31)P and (2)H nuclear magnetic resonance results are consistent with the occurrence of 'defects' in the bilayer in the temperature range between the first and the anomalous phase transitions. It is proposed that conically, PLPC molecules prefer regions with high curvature in the defective bilayer, while DPPE molecules are mostly confined to the flat regions of the bilayers.

Physicochemical characterization of a model digestive mixture by 2H NMR.

2H nuclear magnetic resonance (NMR) spectra were obtained at 30.87 MHz for 8% (w/v) aqueous dispersions of mixtures of bile salts (MBS), mixed intestinal lipids (MIL; myristic acid, monomyristoylglycerol, dimyristoylphosphatidylcholine = 5:1:1), and cholesterol, in which a single lipid component is selectively 2H-labeled. Using the observation that the time-averaged quadrupole splitting of a C2H3 group varies according to whether it exists in a micellar, multilamellar or solid phase, one-, two-, and three-phase regions in the equilibrium phase diagram have been identified. From the intensities of the singlets and powder patterns in the wide-line 2H NMR spectra, the relative amounts of these organized molecular assemblies were determined. With different C2H3-labeled components in samples of identical total composition, the chemical composition of each phase was calculated for one point (20 mol % cholesterol; 50 mol % MIL, and 30 mol % MBS) in a two-phase region of the phase diagram where the 2H NMR spectrum displayed both a sharp spectral component and a broad uniaxial powder pattern. X-ray diffraction measurements on this sample confirmed that the uniaxial powder pattern in the NMR spectra can be assigned to multilamellar vesicles. At this same point in the phase diagram with the 2H label on the alpha-methylene site of myristic acid, both narrow and broad (delta v = 37 kHz) spectral components were again observed. Relaxation time (T1 and T2) measurements of the sharp spectral component indicate that this peak arises from rapidly tumbling aggregates which, at a total lipid concentration of 8% (w/v), are micellar particles and not unilamellar vesicles. These experiments demonstrate the feasibility of structural investigations of model digestive mixtures by 2H NMR.

A study of carbobenzoxy-D-phenylalanine-L-phenylalanine-glycine, an inhibitor of membrane fusion, in phospholipid bilayers with multinuclear magnetic resonance.

The anti-viral and membrane fusion inhibitor, carbobenzoxy-D-phenylalanine-L-phenylalanine-glycine (ZfFG), was studied in phospholipid bilayers, where earlier studies had indicated this peptide functioned. Multinuclear magnetic resonance (NMR) studies were performed with isotopically labeled peptide. A peptide labeled in the glycine carboxyl with 13C was synthesized, and the isotropic 13C-NMR chemical shift of that carbon was measured as a function of pH. A pKa of 3.6 for the carboxyl was determined from the peptide bound to a phosphatidylcholine bilayer. ZfFG inhibits the formation by sonication of highly curved, small unilamellar vesicles. Experiments as a function of pH revealed that this ability of ZfFG was governed by a pKa of 3.7. Therefore the protonation state of the carboxyl of ZfFG appeared to regulate the effectiveness of this anti-viral peptide at destabilizing highly curved phospholipid assemblies. Such destabilization had previously been discovered to be related to the mechanism of the anti-fusion and anti-viral activity of this peptide. The location of the carboxyl of ZfFG in the membrane was probed with paramagnetic relaxation enhancement of the 13C spin lattice relaxation of the carboxyl carbon in the glycine of ZfFG (enriched in 13C). Results suggested that this carboxyl is at or above the surface of the phospholipid bilayer. The dynamics of the molecule in the membrane were examined with 2H-NMR studies of ZfFG, deuterated in the alpha-carbon protons of the glycine. When ZfFG was bound to membranes of phosphatidylcholine, a sharp 2H-NMR spectral component was observed, consistent with a disordering of the glycine methylene segment of the peptide. When ZfFG was bound to N-methyl dioleoylphosphatidylethanolamine (N-methyl DOPE) bilayers at temperatures below 30 degrees C, a large quadrupole splitting was observed. These results suggest that ZfFG likely inhibits membrane fusion from the surface of the lipid bilayer, but not by forming a tight, stoichiometric complex with the phospholipids.

Homophobic attitudes and AIDS risk behavior of adolescents.

Adolescents in the United States are increasingly knowledgeable about acquired immunodeficiency syndrome (AIDS), yet they are notoriously resistant to behavioral changes that would reduce their personal risk, such as practicing abstinence, using condoms, or careful selection of sexual partners. For the present study, we asked 80 heterosexual adolescents about their sexual behavior and intentions to avoid risky behavior, in conjunction with assessing their knowledge and attitudes concerning AIDS and AIDS-related issues. The results suggest that many adolescents do not feel vulnerable to AIDS because they still see AIDS as a Gay disease. Those who are most prejudiced against Gays are, on average, five times more willing to engage in indiscriminant sex as are the least prejudiced group; among males, this effect is even greater. In addition, highly prejudiced adolescents are twice as willing to have sex without using a condom. This study indicates the importance of dealing with homophobic attitudes in the context of AIDS education.

Risk-taking behavior of college students and social forces.

We surveyed 1,900 first-year students at the University of Virginia 1 month after arrival. We looked at drinking and driving practices. Men drank more and they drank more often than women. Our data suggest that in defining frequent heavy drinkers, one should consider body weight. We now define frequent heavy drinking as five or more drinks in a row at least weekly for men, and for women we use three to four drinks or more in a row at least weekly. Frequent heavy drinkers and dangerous drivers appeared disproportionately among students planning to join fraternities and sororities. We believe correction of alcohol abuse and addiction by college students must focus, at least in part, on social organizations, especially fraternities and sororities. Also, we must attend to characterologic features that predispose to alcohol abuse and dependence and dangerous driving practices.

Depression. Nursing implications of a clinical and social problem.

Depression is a phenomenon with concurrent personal, social, and clinical dimensions. Each person is affected by depression differently and expresses depressive symptomatology in a unique manner. Socially, the incidence of depressive illness in the general population is three times that of schizophrenia. The cost of depression in terms of lost days at work and treatment is estimated to be $29 billion in 1991. Diagnosing and treating depressive illnesses depend on the clinical manifestations of the illness and the assessment skills of the practitioner. Different treatment modalities such as psychotherapy, psychopharmacology, and electroconvulsive treatments can be effective singularly or in combination to assist the patient in regaining his or her functionality in daily life.

Outpatient psychogeriatric nursing services: an integrative model.

The complex needs of psychogeriatric patients and their families require specialized outpatient psychogeriatric services. The interaction of physical and mental health and the need for coordinated care places important responsibilities on nursing because it contributes to integrated, multidisciplinary care delivery to these patients and their families. This article presents a model of outpatient psychogeriatric nursing services focused on the community integration of patients and families. Experiences in the development of the Geriatric Neuropsychiatry Clinic at the University of Virginia, Charlottesville, are used as the point of departure from which to describe a model of outpatient psychogeriatric nursing care delivery that is multidisciplinary, clinically innovative, and epidemiologically justified.

Alcohol and cocaine use among first-year college students.

We surveyed 1528 first-year students at the University of Virginia, 1 month after their arrival on campus, who had used alcohol at some time in their lives. Our survey was designed to identify alcohol and cocaine use, and related psychosocial patterns. Men drank more and more often than women. Our data suggest that body weight should be considered in defining those who drink heavily and often. We define 'frequent heavy drinking' as five or more drinks in a row each week for men and three to four drinks or more in a row each week for women. Frequent heavy drinkers, cocaine users, and students with psychosocial problems appeared disproportionately among students planning to join fraternities and sororities. Although first-year students used cocaine infrequently, its users followed the patterns of frequent heavy drinkers. We believe efforts to correct alcohol and cocaine misuse by college students should be directed, in part, at social organizations such as Greek-letter societies. Also, we must attend to psychosocial features that predispose to alcohol and cocaine misuse.

Sudden death from acute cocaine intoxication in Virginia in 1988.

A review of medical examiners' autopsy records revealed that in 1988, 33 residents of Virginia died of acute cocaine intoxication. The subjects were 19 to 45 years old; most were men, used cocaine intravenously, and used other toxic substances with the lethal dose of cocaine.

Psychosocial inventory among first-year college students by patterns of alcohol use.

We surveyed 1703 first-year students at the University of Virginia one month after arrival who used alcohol at some time in their lives. Our survey looked at drinking practices and psychosocial patterns. Men drank more and more often than women. Our data suggest that in defining frequent heavy drinkers, one should consider body weight. Now, we define frequent heavy drinking as five or more drinks in a row at least weekly for men, and for women, we use three to four drinks or more in a row at least weekly. Frequent heavy drinkers and students with psychosocial problems appeared disproportionately among students planning to join fraternities and sororities. We believe efforts to correct alcohol abuse and addiction by college students must focus, at least in part, on social organizations, especially fraternities and sororities. Also, we must attend to psychosocial features that predispose to alcohol abuse and addiction.

Seasonal stability of water balance among schizophrenic patients subject to water intoxication.

1. Diurnal weight gain, afternoon hyponatremia, and polyuria were assessed for one year among eight male schizophrenics subject to water intoxication. 2. The authors normalized the diurnal weight gain (NDWG) as a percentage by subtracting the 7 a.m. weight from the 4 p.m. Weight, multiplying the difference by 100, and then dividing the result by the 7 a.m. weight. 3. NDWG ranged between 2.69 +/- .99 and 3.34 +/- 1.32 percent (F [3, 5] = .885, p = .509) during the four seasons of the year. 4. The seasonal decrease in afternoon serum sodium compared to its morning counterpart ranged between 4.23 +/- 1.96 and 6.14 +/- 2.82 mmol/l (F [3, 5] = 2.212, p = .205). 5. Seasonal polyuria ranged between 8.2 +/- 3.5 and 8.8 +/- 3.2 liters (F [3, 5] = .228, p = .873). 6. Among schizophrenics subject to water intoxication, the seasonal stability in our three parameters of water imbalance suggest they may be used to follow patients with altered water homeostasis over time. This finding has both clinical and research implications.

Chain-length dependence of n-alkane solubility in phosphatidylcholine bilayers: a 2H-NMR study.

Phosphatidylcholine bilayer membranes containing 2H-labelled n-alkanes have been studied by 2H-NMR as a model system for the investigation of molecular theories of general anesthesia. The solubilities of n-alkanes in lipid bilayers have been determined by measurement of the relative intensities of a powder pattern signal arising from orientationally ordered, membrane-soluble alkane and a sharp signal in the 2H-NMR spectrum resulting from isotropically reorienting alkane. The ordering profiles for the ordered n-alkane as determined from the quadrupole splittings for different segments along the chain are similar to those described earlier for n-hexane, n-octane and n-dodecane, suggesting that the restricted motions undergone by the n-alkanes of chain length from 6 to 19 are basically similar. For this homologous series of n-alkanes, it was found that membrane solubility dropped sharply at an alkane chain length which depended on lipid chain length, degree of unsaturation, cholesterol concentration in the bilayer, and temperature. The results show that the incorporation of n-alkanes in lipid bilayers is a complex function of lipid composition. The implications of these results in relationship to the observed 'cut-off' in anesthetic potency in the n-alkane homologous series are discussed.