Log Cl Research Articles

Fresh and recirculated submarine groundwater discharge zones along the central west coast of India

The study area receives an average of 2840.0 mm of rainfall within four months every year. A portion of the rainwater is flown to the sea as surface water, and the other part is percolated into the bottom as groundwater. In coastal aquifers, the groundwater is transported to the sea due to a hydraulic gradient, and it contains a significant quantity of dissolved materials and nutrients. SGD processes impact the ocean productivity, mangrove and coral growth, local acidification and many. To isolate the SGD on the central west coast of India, different data was referred. The GWL concerning MSL contributed significantly to demarcating the SGD zones by considering the positive (>0 m) and negative (<0 m) values of GWL concerning above MSL. Thermal images for SST of pre-monsoon and post-monsoon periods of 2020 exhibit cooler surrounded by warmer, which might be the SGD buffering zones in the off-central west coast of India. By considering the results from GWL and SST, 8 SGD beach sites were identified for the further particularized study. The water samples were collected in March 2022, and analyzed using standard procedures and instruments. Fresh and mixing (recirculated) zones have been isolated by piper, hydrochemical facies evolution, and Ca2++Mg2+/K++Na + Vs log Cl− ionic ratio plots. The aquifer water chemical elements are converting possibly due to ionic exchange processes. The decrease in salinity and conductivity observed in the pore water just below the seawater might be due to the influence of freshwater inputs, helping to isolate the fresh SGD and recirculated SGD zones in the study area. Among 8 sites, 3 were found to be fresh SGD sites and 5 were noticed to be mixing/recirculated SGD sites. Most of these Beaches are bounded by hills, which helps to lead the SGD along the central west coast of India.

Hydrogeochemical investigations to assess groundwater and saline water interaction in coastal aquifers of the southeast coast, Tamil Nadu, India.

Groundwater and saline water interaction is the most common processes in the coastal aquifers that alters the quality of aquifer waters. The quaternary alluvium aquifer system is a significant water resource of southeast coastal Tamil Nadu that provides water supplies for industrial, agriculture, and domestic utilities. Hydrogeochemical investigations were attempted to analyze groundwater-saline water interactions for which a total of three hundred and sixty samples representing surface water, pore water, and groundwater samples collected from three significant locations (location A, B, and C) and analyzed for major ion concentrations. Piper plot infers surface and pore water samples representing saline water type (Na-Cl) in all the three locations due to tidal variation and sand dominant surface layer. Groundwater samples represent (Ca-HCO3) type at location A due to fresh groundwater discharge, mixed or subterranean estuary (Ca, Mg-Cl, HCO3) at location B due to conversion of freshwater (Ca-HCO3) at low tide to saline water (Na-Cl) at high tide, and saline (Na-Cl) water at location C due to proximity and influence of tides. The Cl-/HCO3- vs. Cl- plot represents two water types, such as fresh groundwater (0.5) and strongly affected by seawater intrusion (6.6). The plot (Ca2++Mg2+)/(K++Na+) vs. log Cl- represents freshwater in location A, mixing in location B, and saline water in location C. Groundwater samples observed to be fresh in location A (20.0 km away from the coast), recirculated in location B (9.0 km away from the coast), and saline in location C (0.5 km away from the coast).

The growth and reproductive biology of the coral gall crab, Hapalocarcinus marsupialis Stimpson, 1859 (Crustacea: Cryptochiridae) from Gulf of Aqaba, Red Sea, Egypt

BackgroundGall crabs were described 150 years ago, but little is known about their biology, ecology, and taxonomy. Studying the breeding season can facilitate the understanding of the adaptive strategies and reproductive potential of gall crab and its relationship with the environment and other species.ResultsGrowth and reproductive biology of the coral gall crab, Hapalocarcinus marsupialis, were studied at Gulf of Aqaba, Red Sea, Egypt. A total of 209 specimens were collected from different reef depths during 2014. Relationship between carapace width (CW) and total body wet weight (W) was represented as log W = 0.190 + 2.87 log CW. Growth generally shows negative allometric pattern. While the relation between CW and CL is represented by log CL = 0.019 + 1.009 log CW. This relation is linear and shows an isometric regression coefficient. The overall value for “Kn” is varied from 0.8 to 1.24, with an average of 1.11 ± 0.13, and denotes fitness for females. H. marsupialis shows clear sexual dimorphism and has lengthy definite breeding season characterized by carrying eggs throughout the year. The incubated eggs are semi spherical in shape, with diameter ranges according to maturity stages between 10 and 50 μm. The color of incubated eggs is also varied according to the developmental stage. Most females attain sexual maturity between 2.0 and 2.49 mm CW. Juveniles were recorded during year except the months of January and October. Fecundity varied from 10 to 740 eggs, with an average of 230 ± 173 eggs/female, showing linear relation with carapace width. Significant relationship between carapace width and fecundity was represented by log F = 0.22 + 2.39 log CW.ConclusionThe present study emphasized the reproductive biology of H. marsupialis and explained the size structure, sexual dimorphism, breeding season, fecundity, size at first maturity, and juvenile’s recruitments in the three selected sites Dahab, Nuweiba and Taba along the Gulf of Aqaba.

Carapace length-weight and width-weight relationships of Scylla serrata in Bulungan District, North Kalimantan, Indonesia

Widigdo B, Rukisah, Laga A, Hakim AA, Wardiatno Y. 2017. Carapace length-weight and width-weight relationships of Scylla serrata in Bulungan District, North Kalimantan, Indonesia. Biodiversitas 18: 1316-1323. The mud crab, Scylla serrata lives associated with mangrove ecosystems and is widely distributed in the Indo West-Pacific. The present work was aimed to reveal the carapace length/width-weight relationships of Scylla serrata in two mangrove ecosystem area of Bulungan District, North Kalimantan- Indonesia, i.e. Kahayan Delta and Tibi Island. The crabs were collected by using ambau pancang (trap) for two months from November to December 2016. A total of 522 individuals were collected and their carapace length, carapace width, and weight were measured. The sex ratio of total collected samples (male to female) was 1:0.79. Carapace length and width of S. serrata caught in these two study area ranged from 40 to 89 mm for male; 32 to 91 mm for female and 59 to 128 mm for male; 53 to 122 mm for female, respectively. The carapace length-weight relationships of total samples showed logarithmic equations as follow: W = -3.2194 + 2.9725 Log CL for male and Log W = -2.2010 + 2.3750 Log CL for female. While the carapace width-weight relationships are as follow: W = -3.9162 + 3.1012 Log CW for male and Log W = -2.6001 + 2.3968 Log CW for female. The b values of carapace width-weight relationship indicated that the growth pattern of male was positive allometric and female was negative allometric. Size frequency of crab population is also presented.

Some population characteristics of the pink spiny lobster Palinurus mauritanicus (Gruvel, 1911) caught in the Béni-Saf Bay (Western Algeria)

This study is aimed to pinpoint the morphometrics, state of exploitation dynamic in order to assess the P. mauritanicus (Gruvel, 1911) stock. Specimens were caught by trawlers operating in Beni-Saf Bay. In total 121 individuals were collected: 60 males (49.58%) and 61 (50.41%) females, χ2 test (p<0.05) didn’t show any significant difference between the two sexes. FISAT II software was used to estimate growth parameters, recruitment, mortality and exploitation rates. Total length-total weight, total length, carapace length equations parameters for the entire population were respectively TW=0.0363*TL2.858, Log TL = 0.802*Log CL+ 0.631 indicating a negative allometry growth. The parameters of Von Bertalanffy were: L∞ =32.03 cm, K=0.18 yr-1and t0= -0.16 year-1. Total mortality was estimated Z = 0.760 yr-1, natural maturity M=0.458 yr-1, fishing mortality F=0.302 yr-1 and exploitation ratio E=0.397 reflecting a situation near the full exploitation of the resource.

In silico optimization of pharmacokinetic properties and receptor binding affinity simultaneously: a ‘parallel progression approach to drug design’ applied to β-blockers

The present work exploits the potential of in silico approaches for minimizing attrition of leads in the later stages of drug development. We propose a theoretical approach, wherein ‘parallel’ information is generated to simultaneously optimize the pharmacokinetics (PK) and pharmacodynamics (PD) of lead candidates. β-blockers, though in use for many years, have suboptimal PKs; hence are an ideal test series for the ‘parallel progression approach’. This approach utilizes molecular modeling tools viz. hologram quantitative structure activity relationships, homology modeling, docking, predictive metabolism, and toxicity models. Validated models have been developed for PK parameters such as volume of distribution (log Vd) and clearance (log Cl), which together influence the half-life (t1/2) of a drug. Simultaneously, models for PD in terms of inhibition constant pKi have been developed. Thus, PK and PD properties of β-blockers were concurrently analyzed and after iterative cycling, modifications were proposed that lead to compounds with optimized PK and PD. We report some of the resultant re-engineered β-blockers with improved half-lives and pKi values comparable with marketed β-blockers. These were further analyzed by the docking studies to evaluate their binding poses. Finally, metabolic and toxicological assessment of these molecules was done through in silico methods. The strategy proposed herein has potential universal applicability, and can be used in any drug discovery scenario; provided that the data used is consistent in terms of experimental conditions, endpoints, and methods employed. Thus the ‘parallel progression approach’ helps to simultaneously fine-tune various properties of the drug and would be an invaluable tool during the drug development process.

Processes that control water chemistry and stable isotopic composition during the refilling of Lake Ngami in semiarid northwest Botswana

Summary Lake Ngami in semiarid Botswana was dry until 2009 when it began filling with water because of regional increases in precipitation and from redirection of water to the lake from distributaries of the Okavango River. We measured the physical, chemical and stable isotopic composition of lake water collected at 25 cm below the surface along a ∼18 km axial transect from the inflow river to the distal end of the lake. Our objective was to determine the processes that control water properties and to establish baseline values for future temporal and spatial comparisons. The major ionic concentrations (e.g., Cl−, Na+, Ca2+) and the stable oxygen (δ18O) and hydrogen (δD) isotope ratios show three distinct regions of increasing concentrations and isotopic enrichment, respectively along the transect. The δ18O vs. δD data plot along the Okavango Delta evaporation line and suggest modification of lake water by evaporation. The proportions of the major ions in the inlet water and in the lake were similar and log Cl− vs. log Na+ suggests an evaporative enrichment of solutes. The segmentation of the major solutes and the δ18O and δD into three regions along the axial transect results from differential evaporation of lake recharge from 2010, 2011 and 2012, and are thus controlled by the residence time of recharge in the lake. Unlike the major ions, the dissolved inorganic carbon (DIC) concentrations and the stable carbon isotopic ratios (δ13C) of DIC increase along the axial transect to about midway in the lake, and then reach steady state. The δ13C of dissolved organic matter in the inlet river and lake averaged ∼−25.7 ± 0.3‰ while that for particulate organic carbon decreased from ∼−24‰ in the inlet river to ∼−28‰ in the lake from water column productivity. Carbon cycling in Lake Ngami is controlled by evaporation which increase DIC concentrations and equilibration between carbon in DIC and atmospheric CO2(g). The results show the importance of evaporation and residence time in controlling the solute chemistry and the dominance of atmospheric CO2(g) in controlling carbon cycling during the filling stages of lakes in arid environments.

Impact of Seawater on Distribution of Fluoride and Other Ions in Groundwater of Diplo Area, Thar Desert Pakistan

The role of seawater dilution, along with other water-quality components, has been studied to determine the causes of spatial distribution of high fluoride concentrations in the groundwater of the Diplo sub-district, Thar Desert, Pakistan. Fluoride ion concentration ranges of up to 7.60 mg/L were discovered, with mean and median values of 1.66 and 1.34 mg/L, respectively. Estimates based on the total dissolved solid (TDS) ratio show the impact of seawater intrusion at a percentage of around 8.05% in the groundwater. The major ion chemistry of water in the central diamond shape of the Piper diagram precisely demarcates the phenomenon of the intrusion of seawater into the study area. The plots of Na+K vs. Ca+Mg (meq/L) and log C1 (mg/L) vs. log Ca+Mg/Na+K (meq/L) indicate a mixing of freshwater with seawater. The molar Na/Na+Cl and Ca/Ca+SO4 ratios of the groundwater, and correlation matrices of major ion chemistry, also show a blending of groundwater with seawater. Mutual relationships among Li+, Sr2+, and C1- ions further substantiate the marked influence of the marine environment on the groundwater in the study area.

Sequestration of Alkyltin(IV) Compounds in Aqueous Solution: Formation, Stability, and Empirical Relationships for the Binding of Dimethyltin(IV) Cation by N‐ and O‐Donor Ligands

The sequestering ability of polyamines and aminoacids of biological and environmental relevance (namely, ethylenediamine, putrescine, spermine, a polyallylamine, a branched polyethyleneimine, aspartate, glycinate, lysinate) toward dimethyltin(IV) cation was evaluated. The stability of various dimethyltin(IV) / ligand species was determined in NaClaq at t = 25°C and at different ionic strengths (0.1 ≤ I/mol L−1 ≤ 1.0), and the dependence of stability constants on this parameter was modeled by an Extended Debye-Hückel equation and by Specific ion Interaction Theory (SIT) approach. At I = 0.1 mol L−1, for the ML species we have log K = 10.8, 14.2, 12.0, 14.7, 11.9, 7.7, 13.7, and 8.0 for ethylenediamine, putrescine, polyallylamine, spermine, polyethyleneimine, glycinate, lysinate, and aspartate, respectively. The sequestering ability toward dimethyltin(IV) cation was defined by calculating the parameter pL50 (the total ligand concentration, as −log CL, able to bind 50% of metal cation), able to give an objective representation of this ability. Equations were formulated to model the dependence of pL50 on different variables, such as ionic strength and pH, and other empirical predictive relationships were also found.

Geospatial Methods for Monitoring a Vegetative Treatment Area Receiving Beef Feedlot Runoff

A vegetative treatment area (VTA) offers alternative solutions to traditional feedlot runoff holding ponds, but the distribution of nutrients is not easily defined. Methods for monitoring salt accumulations in soils have been demonstrated at the United States Salinity Laboratory, Riverside, CA. This study was conducted to determine if methods developed to inventory saline soils can be used to inventory a VTA designed to control feedlot runoff. A soil conductivity map was generated at a VTA site using electromagnetic induction equipment (Dualem-1S) and global positioning satellite. The ESAP software package, developed by the United States Salinity Laboratory at Riverside, CA, was used to determine a representative set of (n = 20) soil sampling locations for estimating the chloride distribution in the VTA (Cl(-): selected as an indicator ion to track feedlot runoff). An additional set of (n = 20) stratified random sampling (SRS) locations were selected for comparison. The ESAP-generated, prediction-based sampling plan exhibited better design optimality criteria than the SRS plan. Statistical validation tests confirmed that the regression model estimated from the ESAP-generated sample data was capable of producing accurate and unbiased predictions of the natural log (Cl(-)) levels at the independently chosen SRS sites. The combination of geo-referenced soil conductivity, directed soil sample data, and regression modeling provides a cost-effective tool to observe and manage liquid flow patterns in a VTA.

The dependence of Fe III hydrolysis on ionic strength in NaCl solutions

The influence of ionic strength on FeOH 2+ formation (0.1 m ≤ I ≤ 6.0 m) in NaCl solutions at 25 °C was observed potentiometrically, and can be summarized as log B 1 * = − 2.34 ( ± 0.01 ) − 2.044 I 1 / 2 / ( 1 + 1.70 ( ± 0.08 ) I 1 / 2 ) − 0.228 ( ± 0.005 ) I where B 1* = [FeOH 2+][H +][Fe III] − 1 , brackets denote species concentrations, and [Fe III] is the total Fe III concentration ([Fe III] T) exclusive of hydrolyzed forms of Fe III ([Fe III] = [Fe 3+] + [FeCl 2+] + [FeCl 2 +]). The magnitude of B 1* is well described in terms of Fe III hydrolysis constants ( β 1*) determined in NaClO 4 solutions ( β 1* = [FeOH 2+][H +][Fe 3+] − 1 ), and ferric chloride formation constants determined in moderately acidic solutions ( Cl β 1 = [FeCl 2+][Fe 3+] − 1 [Cl −] − 1 , Cl β 2 = [FeCl 2 +][Fe 3+] − 1 [Cl −] − 2 ): log β 1 * = − 2.179 ( ± 0.012 ) − 2.044 I 1 / 2 / ( 1 + 2.42 ( ± 0.11 ) I 1 / 2 ) + 0.020 ( ± 0.004 ) I log Cl β 1 = 1.26 ( ± 0.01 ) − 3.066 I 1 / 2 / ( 1 + 2.10 ( ± 0.06 ) I 1 / 2 ) + 0.130 ( ± 0.003 ) I log Cl β 2 = 2.53 ( ± 0.16 ) − 5.11 I 1 / 2 / ( 1 + 0.86 ( ± 0.22 ) I 1 / 2 ) + 0.27 ( ± 0.12 ) I Ferric chloride formation constants are strongly medium dependent. At high ionic strengths, FeCl 2+ formation constants are much larger in HClO 4 solutions than in NaClO 4 solutions. In strong acids (HClO 4 + HCl) log Cl β 1 is given as log Cl β 1 = 1.26 ( ± 0.04 ) − 3.066 I 1 / 2 / ( 1 + 1.78 ( ± 0.11 ) I 1 / 2 ) + 0.244 ( ± 0.006 ) I Chloride complexation exerts a strong influence on the magnitude of B 1*. In 0.7 m NaCl, B 1* is smaller than β 1* by a factor of three, and in 6 m NaCl, B 1* is smaller than β 1* by a factor of eighty. Chloride complexation also exerts a strong influence on the enthalpy of Fe III hydrolysis. While observations of the influence of temperature on β 1* in 0.72 m NaClO 4 indicate that the enthalpy for the Fe III hydrolysis reaction is Δ H = 42.7 ± 0.8 kJ mol − 1 [Byrne, R.H., Luo, Y.R., Young, R.W., 2000. Iron hydrolysis and solubility revisited: observations and comments on iron hydrolysis characterizations. Mar. Chem. 70, 23–35], observations of B 1* in 0.7 m NaCl indicate that Δ H = 26.0 ± 1.2 kJ mol − 1 . This result is in good agreement with results obtained via solubility analysis [Liu, X., Millero, F.J., 1999. The solubility of iron hydroxide in sodium chloride solutions. Geochim. Cosmochim. Acta 63, 3487–3497]. Potentiometric observations of Fe III solubility equilibria in 0.7 m NaCl at 25 °C can be summarized as log [ Fe 3 + ] = 4.62 ( ± 0.06 ) − 2.73 ( ± 0.01 ) pH The slope ( n = − 2.73) obtained for freshly precipitated hydrous ferric oxides in 0.7 m NaCl is identical to that observed in previous work [Biedermann, G., Chow, J.T., 1966. Studies on the hydrolysis of metal ions. Acta Chem. Scand. 20 (5), 1376–1388] using aged precipitates in 0.5 m NaCl. This slope is somewhat smaller than that observed in 0.7 m NaClO 4 at 25 °C [ n = − 2.86 ± 0.009; Byrne, R.H., Luo, Y.R., 2000. Direct observations of nonintegral hydrous ferric oxide solubility products: K so*=[Fe 3+][H +] −2.86. Geochim. Cosmochim. Acta. 64, 1873–1877.].

Interspecies pharmacokinetic scaling of oltipraz in mice, rats, rabbits and dogs, and prediction of human pharmacokinetics

Dose-independent pharmacokinetics of oltipraz after intravenous and/or oral administration at various doses to mice, rats, rabbits and dogs were evaluated. After both intravenous and/or oral administration of oltipraz to mice (5, 10 and 20 mg/kg for intravenous and 15, 30 and 50 mg/kg for oral administration), rats (5, 10 and 20 mg/kg for intravenous and 25, 50 and 100 mg/kg for oral administration), rabbits (5, 10 and 30 mg/kg for intravenous administration) and dogs (5 and 10 mg/kg for intravenous and 50 and 100 mg/kg for oral administration), the total area under the plasma concentration-time curve from time zero to time infinity (AUC) values of oltipraz were dose-proportional in all animals studied. Animal scale-up of some pharmacokinetics parameters of oltipraz was also performed based on the parameters after intravenous administration at a dose of 10 mg/kg to mice, rats, rabbits and dogs. Linear relationships were obtained between log time-averaged total body clearance (Cl) x maximum life-span potential (MLP) (1 year/h) and log species body weight (W) (kg) (r=0.999; p=0.0015), log Cl (l/h) and log W (kg) (r=0.979; p=0.0209), and log apparent volume of distribution at steady state (V(ss)) (l) and log W (kg) (r=0.999; p=0.0009). The corresponding allometric equations were ClxMLP=49.8 W(0.861), Cl=5.20 W(0.523) and V(ss)=4.46 W(0.764). Interspecies scale-up of plasma concentration-time data for the four species using pharmacokinetic time of dienetichron resulted in similar profiles. In addition, concentrations of oltipraz in a plasma concentration-time profile for humans predicted using the four animal data fitted to the dienetichron time transformation of animal data.

Interspecies pharmacokinetic scaling of DA-8159, a new erectogenic, in mice, rats, rabbits and dogs, and prediction of human pharmacokinetics

Time-averaged total body clearance (Cl) and apparent volume of distribution at steady state (V(SS)) of DA-8159 after intravenous administration to mice (30 mg/kg), rats (30 mg/kg), rabbits (30 mg/kg) and dogs (3 mg/kg) were analysed as a function of species body weight (W) using the allometric equation for interspecies scaling, and were used to predict those in humans. Significant linear relationships were obtained between log Cl (l/h) and log W (kg) (r = 0.992; p = 0.0079) and log V(SS) (l) and log W (kg) (r = 0.999; p < 0.0001). The corresponding allometric equations were Cl = 4.36 W(0.492) and V(SS) = 6.41 W(0.911). These allometric equations were extrapolated to predict the Cl and V(SS) for DA-8159 in humans based on the 70 kg body weights. In addition, concentrations in the plasma-time profile predicted using the four animal data fitted to a complex Dedrick plot of animal data. Our results indicated that the DA-8159 data obtained from four laboratory animals could be utilized to generate preliminary estimates of the pharmacokinetic parameters in humans. These parameters can serve as guidelines for better planning of clinical studies.

Prooxidant toxicity of polyphenolic antioxidants to HL-60 cells: description of quantitative structure-activity relationships

Polyphenolic antioxidants exhibited a dose-dependent toxicity against human promyelocytic leukemia cells (HL-60). Their action was accompanied by malondialdehyde formation, and was partly prevented by desferrioxamine and the antioxidant N, N′-diphenyl- p-phenylene diamine. This points to a prooxidant character of their cytotoxicity. A quantitative structure-activity relationship (QSAR) has been obtained to describe the cytotoxicity of 13 polyphenolic antioxidants belonging to three different groups (flavonoids, derivatives of gallic and caffeic acid): log cL 50 (μM)=(2.7829±0.2339)+(1.2734±0.4715) E p/2 (V)−(0.3438±0.0582) log P ( r 2=0.8129), where cL 50 represents the concentration for 50% cell survival, E p/2 represents the voltammetric midpoint potential, and P represents the octanol/water partition coefficient. Analogous QSARs were obtained using enthalpies of single-electron oxidation of these compounds, obtained by quantum-mechanical calculations. These findings clearly point to two important characteristics determining polyphenol cytotoxicity, namely their ease of oxidation and their lipophilicity.

Outer ear temperature and time of death

From a research sample of 138 corpses, divided into four subgroups of ambient storage temperature (0–5 °C, 6–10 °C, 11–15 °C and 16–23 °C) four linear regression formulae of actual versus estimated post-mortem interval were obtained (‘interval’ formulae) using a single outer ear temperature measurement on both sides. This method showed the best correlation coefficient among five other methods previously proposed for time of death determination (rectal temperature, vitreous K +, CSF K +, blood log Na + K + and log Cl −), however its results were less accurate than those obtained with a multivariate equation combining several of the above mentioned methods. Eventually an equation expressing time of death (TOD) as a function of outer ear temperature (OE T °) and ambient temperature was also established from the whole research sample (‘global’ formulae). On a different sample of 141 corpses the regression formulae (‘interval’ and ‘global’) for the outer ear temperature were compared to three methods based on a single rectal temperature measurement (‘rule of thumb’ 1 and 2, Henssge nomogram) and therefore useful at the scene; the results of all methods were compared within the four subgroups of ambient temperature as well as in three subgroups of different post-mortem interval lengths (<7 h, <10 h, <15 h). In all cases the outer ear temperature formulae provided better results than the rectal temperature methods (especially Henssge nomogram and rule of thumb 1). Moreover they did not show any post-mortem plateau which was present in almost 30% of cases when rectal temperature was measured in corpses kept at ambient temperature above 15 °C. Our results show that outer ear temperature measurement is the method which provides the best simplicity/quality ratio and should therefore be proposed for use at the scene when conditions are similar to those of our experiment (within buildings). A software equipped thermometer is required in order to use in each case the appropriate formula and confidence interval.

Characteristics, determinants and interpretations of acute lethality in daphnids exposed to complex waste leachates

Acute lethality of the water flea Daphnia magna exposed to leachate runoff samples from 35 Finnish mixed waste disposal sites was measured with 24 h tests without dilutions, followed by standard 48 h tests, and accompanied by chemical analyses of water quality. Toxicity was observed in 1 3 of the 343 screening test samples (including dilute ones), and at 3 4 of the sites. The average 48h-EC(I)50 value of the toxic samples, as determined by a power function of linear estimates of Median Survival Time, was 50% dilution (0.5 C 0). The average 24 h toxicity was slightly less (0.61 C 0). There was a strong correlation between lethality in screening test (LETH_24h) and 48h-EC (I) 50 ( r = 0.85 ∗∗∗, S = 0.77 ∗∗∗ ). Screening test response was concentrated in areas of total or no lethality. Very significant ( p < 0.1%) linear and rank correlations were found between lethality and general water quality variables, e.g. concentrations of Cl −, NH 4-N and light metals. However, sometimes lethality was not observed even though the concentrations of toxic substances exceeded those reported to be acutely lethal in pure solutions, suggesting suppression of toxicity or method differences, and constituting false negatives. The inclusion of Cl − as a variable explaining variation in standard test lethality increased r 2 from 0.73 in the simple linear regression model 48h-EC(I)50 = 110 − 0.755 LETH_24h to 0.77 in the model 48 h EC(I)50 = 102 − 0.00507 (LETH_24h) 2 − 0.396 (log Cl −) 2. The applicability of standard and simplified acute Daphnia tests in the characterization and assessment of toxicological risks from waste leachates was discussed.

Effect of malaria infection and endotoxin-induced fever on phenacetin o-deethylation by rat liver microsomes

We have investigated the effect of malaria infection with the rodent parasite Plasmodium berghei and fever induced by Escherichia colt endotoxin on the metabolism of phenacetin to paracetamol by rat liver microsomes from young (4 weeks old) male Wistar rats (N = 5 in control and fever groups; N = 10 in malaria-infected group). Following determination of % parasitaemia, the malaria-infected group was divided into a low parasitaemia subgroup (N = 5; mean % parasitaemia = 9.87 ± 2.6) and a high parasitaemia subgroup (N = 5; mean % parasitaemia = 36.6 ± 8.1). The control group received normal saline. Total microsomal protein was not significantly affected by fever or malaria infection while cytochrome P450 levels were reduced by approximately 50% in the high parasitaemia subgroup, 20% in the low parasitaemia subgroup and 20% in the endotoxin-treated group. Phenacetin-O-deethylation kinetics were biphasic in both control and malaria-infected rats, but monophasic in endotoxin-treated rats. Total apparent intrinsic clearance ( CL int.total; calculated as V max/ K m ; V max is maximum velocity, K m is Michaelis constant) of phenacetin was reduced approximately 6-fold in low parasitaemia, 30-fold in high parasitaemia and 35-fold in fever. There was a poor correlation between CL int.total and % parasitaemia ( r = −0.6). However, log CL int.total correlated inversely with % parasitaemia ( r = −0.9), suggesting that CL int.total decreased exponentially with an increase in % parasitaemia. Phenacetin O-deethylation is a marker for cytochrome P4501A2 activity and the results of the present study suggest that both malaria infection and fever might specifically reduce P4501A2 activity in the rat.

Influence of sex and age on fluorouracil clearance.

Currently, fluorouracil (5-FU) is one of the major drugs used in cancer chemotherapy. Several investigators, including ourselves, have demonstrated a link between abnormalities in 5-FU clearance (Cl) and the risk of developing more or less 5-FU-related toxicities. Age and sex are among the host factors that have been implicated in the pharmacokinetic variability of drugs. Presently, no data are available on the possible influence of sex and age on 5-FU Cl. Three hundred eighty patients (mean age, 61.7 years; range, 25 to 91; 301 men and 79 women) with squamous cell carcinoma (sre) of the head and neck were treated in our institution between 1987 and 1991. 5-FU Cl was determined for a total of 1,092 chemotherapy cycles. Each cycle consisted of cisplatin and 5-day continuous intravenous infusion 5-FU (daily doses ranging between 365 and 1,224 mg/m2). 5-FU Cl values (L/h/m2) showed a wide dispersion for both men (median, 179; range, 29 to 739) and women (median, 155; range, 56 to 466). 5-FU Cl values were lower significantly for women compared with men (P = .0005). When adjusted for age and dose, the influence of sex on log Cl remained significant (P = .013). There was no evidence that age modified 5-FU Cl when adjusted for sex and dose. Interestingly, for both men and women, the oldest patients (greater than 70 years) maintained their ability to clear 5-FU with daily doses that ranged from 500 to 1,000 mg/m2. These data indicate that the capacities to clear 5-FU are lower in women compared with men and are not influenced by age. It would be of interest to know whether this sex-related difference in 5-FU Cl may be clinically relevant by considering both toxicity and tumor response to 5-FU treatment.

Effects of body size and temperature on the metabolic rate of Penaeus monodon

Laboratory measurements of oxygen consumption were made on Penaeus monodon (Fabricius) from protozoea to adult stage at temperatures between 15° and 35°C. The logarithmic relationship between weight-specific respiration rate (WRt) and temperature (T) for two size groups, Protozoea 1 (PZ1) to Postlarva 1 (PL1) and PL to adult, are given as; WRt=100.431+0.0146 (T) (ml O2 g-1 h-1) and WRt=10-0.948+0.0338 (T) (ml O2 g-1 h-1), respectively. Additionally, equations relating metabolic rate, temperature and size for the two size groups are; PZ1-PL1: log M=0.431+0.0146T+(1.25 (log TL)+0.579), and PL1-adult: log M=-0.948+0.0338T+(2.60(log CL)-0.683), where M=oxygen consumption in ml O2 individual -1h-1, T=temperature in °C, TL=total length in cm, and CL=carapace length in cm. Activation energies of 6 186.75 J for PZ1-PL1 and 14 066.62 J for PL-adults point to different metabolic pathways or to differences in the ratio between the metabolic pathways used.

Comparisons of Shell Morphology among Turtles of the Kinosternon minor Complex

-Musk turtles of the Kinosternon minor complex (K. minor minor, K. m. peltifer, K. m. minor x K. m. peltifer, K. depressum, and presumed K. depressum x K. m. peltifer) were examined for proportional differences in shell morphology. Kinosternon m. peltifer was the most distinct taxon, differing significantly in slope and intercept of the growth curve log CH versus log CL. Discrimination between K. depressum populations from central Alabama and presumed intermediate populations (K. depressum x K. m. peltifer) from west-central Alabama was not possible based on the characters used in the analysis. However, discriminant analysis showed these populations were significantly different from the K. m. peltifer populations examined. These findings support the hypothesis, advanced in other studies, that K. depressum is a distinct species. Lacking empirical data to the contrary, these results also suggest that the presumed intermediate populations in west-central Alabama are referable to K. depressum.