A Temporally Explicit Production Efficiency Model for Fuel Load Allocation in Southern Africa

Abstract We present a regional fuel load model (1 km² spatial resolution) applied in the southern African savanna region. The model is based on a patch-scale production efficiency model (PEM) scaled up to the regional level using empirical relationships between patch-scale behavior and multi-source remote sensing data (spatio-temporal variability of vegetation and climatic variables). The model requires the spatial distribution of woody vegetation cover, which is used to determine separate respiration rates for tree and grass. Net primary production, grass and tree leaf death, and herbivory are also taken into account in this mechanistic modeling approach. The fuel load model has been calibrated and validated from independent measurements taken from savanna vegetation in Africa southward from the equator. A sensitivity analysis on the effect of climate variables (incoming radiation, air temperature, and precipitation) has been conducted to demonstrate the strong role that water availability has in determining productivity and subsequent fuel load over the southern African region. The model performance has been tested in four different areas representative of a regional increasing rainfall gradient—Etosha National Park, Namibia, Mongu and Kasama, Zambia, as well as in Kruger National Park, South Africa. Within each area, we analyze model output from three different magnitudes of canopy coverage (<5, 30, and 50%). We find that fuel load ranges predicted by the model are globally in agreement with field measurements for the same year. High rainfall sustains green herbaceous production late in the dry season and delays tree leaf litter production. Effect of water on production varies across the rainfall gradient with delayed start of green material production in more arid regions.     

Addition of interleukin-2in vitro augments detection of lymphokine-activated killer activity generatedin vivo

Summary Thein vivo administration of repetitive weekly cycles of interleukin-2 (IL-2) to patients with cancer enhances the ability of freshly obtained peripheral blood lymphocytes (PBL) to lyse both the natural-killer(NK)-susceptible K562 and the NK-resistant Daudi targets. Lysis of both targets is significantly augmented by inclusion of IL-2 in the medium during the cytotoxicity assay. This boost is much greater for cells obtained following thein vivo IL-2 therapy than for cells obtained prior to the initiation of therapy or for cells from healthy control donors. In addition to direct lytic activity, the PBL obtained followingin vivo IL-2 show a rapid increase in lymphokine-activated killer (LAK) activity with more prolongedin vitro IL-2 exposure, indicating that LAK effectors primedin vivo respond with secondary-like kinetics to subsequent IL-2in vitro. Lymphocytes from healthy control individuals, cultured in IL-2 under conditions attempting to simulate thein vivo IL-2 exposure, function similarly to PBL obtained from patients following IL-2, in that low-level LAK activity was significantly boosted by inclusion of IL-2 during the cytotoxic assay and the cells also responded with secondary-like kinetics to subsequent IL-2in vitro. The augmentation of the LAK effect was also dependent on the dose of IL-2 added during the 4-h⁵¹Cr-release cytotoxicity assay, with higher doses of IL-2 having a more pronounced effect. While continuous infusion of IL-2 induces a greater cytotoxic potential per milliliter of blood obtained from patients, the peak serum IL-2 levels attained are greater with bolus IL-2 infusions. These pharmacokinetic results, together with the IL-2 dose dependence of LAK activity generatedin vivo shown in this report, suggest that a combination of treatment with bolus IL-2 infusions superimposed on continuous IL-2 infusion may transiently expose IL-2 dependent LAK cells, activatedin vivo, to higher concentrations of IL-2, facilitating theirin vivo cytotoxic potential.This work was supported by NIH contract NO1 CM-47669-02, NIH grants CA-32685, RR-031086, NO1 CM-47669-03, and American Cancer Society grant CH-237     

Isolation and characterization of conditional adherent and non-type 1 fimbriated Salmonella typhimurium mutants

Mutations in the genes encoding the type 1 fimbriae of Salmonella typhimurium were isolated by selecting for the deletion of Tn10 inserted adjacent to the chromosomal fim+ genes and screening for the loss of mannose-sensitive haemagglutination (HA) activity. S. typhimurium strains with Tn10 insertions in ahp were hypersensitive to peroxides, and tetracycline-sensitive derivatives of ahp::Tn10 mutants displayed two fim mutant phenotypes. The predominant class of fim mutants did not synthesize type 1 fimbriae. A second type of fim mutant synthesized type 1 fimbriae and exhibited a conditional lipoic acid requirement for HA. A fim-lip conditional mutant synthesized type 1 fimbriae when grown in Mueller-Hinton broth but the haemagglutinating activity of the fimbriae was dependent upon the addition of lipoic acid to the growth medium. Independently isolated lip mutations did not demonstrate a similar pleiotropic effect on HA. Western blots of fimbriae extracted from a fim-lip conditional mutant that was grown under permissive and restrictive conditions indicated the presence of 33 and 36.6 kDa proteins in HA+ fimbriae that were absent in HA- fimbriae. The HA+ phenotype of both conditional and non-fimbriated mutants was restored by transformation with cloned genes encoding S. typhimurium type 1 fimbriae.     

Species differences and interindividual variation in liver microsomal cytochrome P450 2A enzymes: effects on coumarin, dicumarol, and testosterone oxidation.

Antibody against purified CYP2A1 recognizes two rat liver microsomal P450 enzymes, CYP2A1 and CYP2A2, that catalyze the 7 alpha- and 15 alpha-hydroxylation of testosterone, respectively. In human liver microsomes, this antibody recognizes a single protein, namely CYP2A6, which catalyzes the 7-hydroxylation of coumarin. To examine species differences in CYP2A function, liver microsomes from nine mammalian species (rat, mouse, hamster, rabbit, guinea pig, cat, dog, cynomolgus monkey, and human) were tested for their ability to catalyze the 7 alpha- and 15 alpha-hydroxylation of testosterone and the 7-hydroxylation of coumarin. Antibody against rat CYP2A1 recognized one or more proteins in liver microsomes from all mammalian species examined. However, liver microsomes from cat, dog, cynomolgus monkey, and human catalyzed negligible rates of testosterone 7 alpha- and/or 15 alpha-hydroxylation, whereas rat and cat liver microsomes catalyzed negligible rates of coumarin 7-hydroxylation. Formation of 7-hydroxycoumarin accounted for a different proportion of the coumarin metabolites formed by liver microsomes from each of the various species examined. 7-Hydroxycoumarin was the major metabolite (greater than 70%) in human and monkey, but only a minor metabolite (less than 1%) in rat. The 7-hydroxylation of coumarin by human liver microsomes was catalyzed by a single, high-affinity enzyme (Km 0.2-0.6 microM), which was markedly inhibited (greater than 95%) by antibody against rat CYP2A1. The rate of coumarin 7-hydroxylation varied approximately 17-fold among liver microsomes from 22 human subjects. This variation was highly correlated (r2 = 0.956) with interindividual differences in the levels of CYP2A6, as determined by immunoblotting. These results indicate that CYP2A6 is largely or entirely responsible for catalyzing the 7-hydroxylation of coumarin in human liver microsomes. Treatment of monkeys with phenobarbital or dexamethasone increased coumarin 7-hydroxylase activity, whereas treatment with beta-naphthoflavone caused a slight decrease. These results suggest that environmental factors can increase or decrease CYP2A expression in cynomolgus monkeys, which implies that environmental factors may be responsible for the large variation in CYP2A6 levels in humans, although genetic factors may also be important. In contrast to rats and mice, the expression of CYP2A enzymes in cynomolgus monkeys and humans was not sexually differentiated. Despite their structural similarity to coumarin, the anticoagulants dicumarol and warfarin do not appear to be substrates for CYP2A6. The overall rate of dicumarol metabolism varied approximately 5-fold among the human liver microsomal samples, but this variation correlated poorly (r2 = 0.126) with the variation observed in CYP2A6 levels and coumarin 7-hydroxylase activity.(ABSTRACT TRUNCATED AT 400 WORDS)     

Topical Fat Reduction

The fat on women's thighs is more difficult to mobilize due to increased α-2 adrenergic receptor activity induced by estrogen. Lipolysis can be initiated through adipocyte receptor stimulation (β adrenergic) or inhibition (adenosine or α-2 adrenergic) or by inhibition of phosphodiesterase. Since many women desire regional thigh fat loss, a series of clinical trials were initiated using one thigh as a double-blinded control. Trial #1: Five overweight women had injections of isoproterenol at intervals around the thigh three times a week for 4 weeks with diet and walking. Trial #2: Five overweight woman had ointment containing forskolin, yohimbine and aminophylline applied to the thigh five times a week for 4 weeks after hypertonic warm soaks with a diet and walking. Trial #3: Eighteen overweight women were divided into three groups of six and trial #2 was repeated with each agent alone vs. placebo using forskolin, yohimbine or aminophylline in separate ointments. Trial #4: Thirty overweight women had 10% aminophylline ointment applied to the thigh five times a week for 6 weeks with diet and walking. Chemistry panel, theophylline level and patch testing wereperformed. Trial#5: Twelve women had trial #4 repeated with 2% aminophylline cream without a diet or walking. Trial #6: Trial #5 was repeated with 0.5% aminophylline cream. All trials except yohimbine ointment gave significantly more girth loss from the treated thigh (p < 0.05 to p < 0.001). Chemistry panel showed no toxicity. Theophylline was undetectable and patch testing was negative. We conclude that topical fat reduction for women's thighs can be achieved without diet or exercise.     

The response of tropical Atlantic decapod crustaceans to artificially lighted trawls

Micronektonic decapod crustaceans were sampled repeatedly ata depth of 200 ± 25 m at two positions centred on 20°30'N,19°40'W and 31°10'N, 21°05'W to assess their responseto an artificial light fitted to an opening/closing rectangularmidwater trawl. Of the 20 decapod species identified, the numbersand biomass of the three numerically dominant diel migrantsOplophorus spinostu, Sysiellaspis debilis and Acanthephyra purpureawere significantly reduced in hauls taken with the artificiallight switched on, when compared with catches with it switchedoff. There was little measurable response in the frequentlyoccurring species Gennadas valens or Gennadas brevirostris,or in other less frequently occurring species.     

Low serum testosterone concentrations in patients with carcinoma of the pancreas

The detection of high activities of two sex-steroid biosynthetic enzymes—aromatase and 5-alpha-reductase—in pancreatic carcinoma tissue suggested the possibility that these enzymes may influence the circulating concentrations of sex-steroid hormones. Mean serum testosterone concentrations in 22 men and women with exocrine carcinoma of the pancreas were significantly lower than those in 20 healthy controls and 27 patients with other known malignancies, who were of similar age and sex composition. Low serum testosterone concentrations may be due to uptake by and metabolism within the tumour; alternatively, patients with low androgen concentrations may be at greater risk of developing pancreatic carcinoma.     

Blockade of reflex venous capacitance responses in liver and spleen by hexamethonium, atropine, and surgical section.

Since hexamethonium and surgical section have been used to prevent reflex splanchnic capacitance responses, we examined the effectiveness of these procedures in blocking responses to direct stimulation of preganglionic fibres in the splanchnic nerves. Liver blood volume was measured by plethysmography and splenic blood volume by weighing in cats anesthetized by pentobarbital. The cats were adrenalectomized to prevent adrenal catecholamine secretion in response to splanchnic nerve stimulation. Hexamethonium (10 and 20 mg/kg) alone or atropine (1 mg/kg) alone caused only a small variable block of the responses to preganglionic nerve stimulation. A combination of the two drugs essentially produced a complete block of the liver capacitance response, but a significant response still persisted in the spleen. Surgical section of the postganglionic nerve bundles around the hepatic and splenic arteries completely abolished the responses to preganglionic stimulation. It is concluded that a relatively complete block of reflex splanchnic capacitance responses requires either a combination of hexamethonium and atropine or surgical section of the postganglionic nerves.     

The isolation and properties of a denitrifying bacterium of the genus Flavobacterium

A previously undescribed denitrifying bacterium was isolated from soil. The cells are small gram-negative rods, asporogenous, and non-motile. Colonies become yellow after long exposure to light. This colouring is due to the production of a carotenoid pigment. The organism shows no fermenting activity, and grows only in the presence of one of the following electron acceptors: NO _inf2 ^sup- , N₂O, and O₂. It does not reduce nitrate. It gives a positive oxidase test and has a cytochrome c and catalase. It requires no growth factors, is a chemoorganotroph and uses only sugars as carbon and energy supply. The DNA base composition is 40.8 moles percent GC. Although presenting the physiological characteristics of a pseudomonad, the organism described has been placed in the genus Flavobacterium because of its pigmentation and its low GC percentage.     

Photokinesis in the teleost fish Danio malabaricus

Summary Photokinesis as shown by the rapidly moving fish Danio malabaricus was examined in two experiments.In Experiment I, which involved sequences of short periods of light and darkness, the Ss for the most part showed a positive relationship between light intensity and level of activity. This reaction included a well differentiated response to abrupt intensity change, the effect of the transition from darkness to light being marked. Level of activity in both light and dark periods tended to fall; after a certain point, however, it rose again in the light but continued to fall in the darkness.In Experiment II, successive increases in the total area of lighted space available were matched by increases in the total length of time spent there by the Ss. The overall reaction, however, was initially photonegative and became more so as the experiment progressed. The range of most frequent periods of time spent in the lighted area increased gradually, while the length of entries into the shaded area gradually decreased, in the course of the experiment. But for a lighted area the Ss' length of entry was shorter than for the corresponding dark area, the choice of period was more precise, there were fewer longer periods, and the range was less. In the last condition, the Ss divided their time approximately equally between the lighted 7/8 and the shaded 1/8 of the area available. The number of times the Ss crossed from one area to the other almost doubled during the experiment.The author wishes to express his gratitude to Prof. G. Thinès for his help and encouragement. He was supported by a research grant from N. A. T. O., administered through the Science Research Council, London. The findings reported formed part of a study submitted as a doctoral dissertation at the Université de Louvain. The raw data is tabulated in this study and may be consulted at the Institut de Psychologie et des Sciences Pédagogiques. Address after 1 October: Department of Psychology, Bryn Mawr College, Bryn Mawr, Pennsylvania, U.S.A.