Effects of Mercuric Chloride on the Hydraulic Conductivity of Tomato Root Systems (Evidence for a Channel-Mediated Water Pathway).

A pressure-flux approach was used to evaluate the effects of HgCl2 on water transport in tomato (Lycopersicon esculentum) roots. Addition of HgCl2 to a root-bathing solution caused a large and rapid reduction in pressure-induced root water flux; the inhibition was largely reversible upon addition of [beta]-mercaptoethanol. Root system hydraulic conductivity was reduced by 57%. There was no difference between treatments in the K+ concentration in xylem exudate. The results are consistent with the presence of a protein-mediated path for transmembrane water flow in tomato roots.

Salt Tolerance of Glycinebetaine-Deficient and -Containing Maize Lines.

Pairs of homozygous near-isogenic glycinebetaine-containing (Bet1/Bet1) and -deficient (bet1/bet1) F8 lines of Zea mays L. (maize) were tested for differences in salt (150 mM NaCl or 127.25 mM NaCl plus 22.5 mM CaCl2) tolerance. The Bet1/Bet1 lines exhibited less shoot growth inhibition (as measured by dry matter accumulation, leaf area expansion rate and/or, plant height extension rate) under salinized conditions in comparison to their nearisogenic bet1/bet1 sister lines. These growth differences were associated with maintenance of a significantly higher leaf relative water content, a higher rate of carbon assimilation, and a greater turgor in Bet1/Bet1 lines than in bet1/bet1 lines under salinized conditions. These results strongly suggest that a single gene conferring glycinebetaine accumulation (and/or a tightly linked locus) plays a key role in osmotic adjustment in maize.

Chemically Induced Cuticle Mutation Affecting Epidermal Conductance to Water Vapor and Disease Susceptibility in Sorghum bicolor (L.) Moench.

Analysis of Sorghum bicolor bloomless (bm) mutants with altered epicuticular wax (EW) structure uncovered a mutation affecting both EW and cuticle deposition. The cuticle of mutant bm-22 was about 60% thinner and approximately one-fifth the weight of the wild-type parent P954035 (WT-P954035) cuticles. Reduced cuticle deposition was associated with increased epidermal conductance to water vapor. The reduction in EW and cuticle deposition increased susceptibility to the fungal pathogen Exserohilum turcicum. Evidence suggests that this recessive mutation occurs at a single locus with pleiotropic effects. The independently occurring gene mutations of bm-2, bm-6, bm-22, and bm-33 are allelic. These chemically induced mutants had essentially identical EW structure, water loss, and cuticle deposition. Furthermore, 138 F2 plants from a bm-22 x WT-P954035 backcross showed no recombination of these traits. This unique mutation in a near-isogenic background provides a useful biological system to examine plant cuticle biosynthesis, physiology, and function.

Involvement of leukocytes in the oxygenation and chlorination reaction of phenylbutazone.

A center carbon atom of 1,3-diketone moiety of phenylbutazone was oxidized to give three metabolites--4-hydroxyphenylbutazone (metabolite I), 4-hydroperoxyphenylbutazone (metabolite II) and 4-chlorophenylbutazone (metabolite III)--by the action of enzymes present in leukocyte extract obtained from peritoneal exudate of rats. Both metabolites II and III were produced by peroxidases, while metabolite I was produced by enzymes other than the peroxidases.

Review of limited systemic absorption of orlistat, a lipase inhibitor, in healthy human volunteers.

Orlistat, a lipase inhibitor, acts locally in the gastrointestinal tract. Systemic absorption is not required for its efficacy, but knowledge of the extent of its systemic absorption is important for its safe use in obese patients, the intended target population. Pharmacokinetic screening was carried out by monitoring plasma concentrations of unchanged orlistat in 25 phase 1 studies (including two mass balance studies) in normal and obese healthy volunteers. The results of these studies indicate an extremely low degree of systemic absorption for orlistat when administered with a hypocaloric, well-balanced diet with 20% to 30% of calories derived from fat (50-80 gm). To further characterize the pharmacokinetics and excretion pathways of orlistat, two mass balance studies using 14C-labeled orlistat were conducted. After oral dosing of radiolabeled orlistat with a fatty meal (28-30 gm fat), almost the entire dose was recovered from fecal samples; little was found in plasma and urine. It is concluded that systemic absorption of orlistat is negligible; at a clinically efficacious dose level, orlistat is unlikely to produce systemic lipase inhibition.

Interference effects in the conservation of weight.

On the assumption that the ability to overcome the effects of interference between the physical properties of an object is a basic component in the acquisition of conservation, we hypothesized that children would tend to negate conservation not only when the form of an object is altered but also when, without deforming the object, one of its properties (e.g., color or temperature) is altered; when variations (e.g., movement or orientation) are introduced into the concrete situation in which weight is exerted; or when other spatial properties (e.g., volume or surface) are made to interact with weight. The results indicate that children up to 8 years of age may have difficulty accepting the conservation of weight even when a transformation does not deform the object and that children up to 13 years may accept the conservation of weight but may find it difficult to explain why an object appears heavier in those instances where weight has to be coordinated with another spatial property. The theoretical implications of these results are discussed.

The grafting of burns with cultured epidermis as autografts in man. Two case reports.

In two patients full-thickness burns were grafted with cultured autologous epidermis obtained using the technique described by H. Green. The grafts only took partially but produced satisfactory covering. Better efficiency and more information about the long-term characteristics of the resulting skin are necessary before routine use can be recommended.

[Postoperative analgesic effect of pethidine injected epidurally]. / Effets analgésiques postopératoires de la péthidine injectée par voie péridurale.

Postoperative pain was treated by epidural administration of 30 to 50 mg pethidine (5 mg X ml-1) in a group of 36 patients who had undergone retropubic prostatectomy. Surgery was carried out under epidural anaesthesia with lidocaine. Pain was assessed by means of the visual analogue scale. A general study of the effects of injections and reinjections showed that analgesia thus obtained was excellent at the first hour after injection and lasted 3 to 5 h. The effect of the first postoperative injection on spontaneous pain was studied in 14 patients. Statistical analysis (Wilcoxon test) demonstrated that the fall in pain score was significant at the first and third hours after injection, but not significant at the fifth hour. The analgesia to that pain produced by coughing was studied in 11 patients. There was a significant decrease in pain at the first hour after injection; differences in pain scores at the third hour were not significant. No noticeable side-effect was observed. It was concluded that low doses of epidural pethidine were efficient on postoperative pelvic abdominal pain, but that doses should be increased if painless coughing was required.

[Effect of experimental interventions provoking the start of molting on the secretory activity of cerebral glands of Lithobius forficatus L. (Myriapoda Chilopoda)]. / Influence d'interventions expérimentales provoquant le déclenchement de la mue sur l'activité sécrétoire des glandes cérébrales chez Lithobius forficatus L. (Myriapode Chilopode).

In Lithobius forficatus, the removal of the two antennae or of 10-15 walking legs and the ecdysteroid supply induces ecdysis. The effects of these experiments has been studied on the secretory cycle of the cerebral glands; it must be reminded that these neurohaemal organs exert a moderating role on moulting. The removal of the antennae leads to injuries in some of the protocerebral neurosecretory cell axonal endings. Correlatively, a slight decrease can be observed in the glandular activity. The removal of the walking legs disturbs the secretory activity of the cerebral glands, whereas the axonal endings do not present injuries. It seems that the removal does not act-through the protocerebral neurosecretory cells. After ecdysteroid supply, the axonal endings are intact and the glandular activity is not affected. Ecdysteroids seem to stimulate the metabolism via the pars intercerebralis. These reported results show that moulting can be induced by various pathways. Moreover, the cerebral glands are not the only organs exercing a role in the control of moulting; complexe interactions exist between endocrine centres, the nervous system and environmental factors.

Effect of gonadectomy on the secretory activity of the cerebral glands in Lithobius forficatus L. (Myriapoda Chilopoda).

Castrated Lithobius forficatus L. showed increased activity of the cerebral glands which are cephalic neurohemal organs exerting a role in spermatocyte and oocyte growth. This glandular hyperactivity is characterized by higher activity of the Golgi apparatus. The reaction, although comparable in both sexes, is apparently more pronounced after ovariectomy. About 50 days after castration glandular cells showed signs of injury while their activity remained similar or somewhat lower in comparison with controls. It is suggested that the glandular hyperactivity arises from the cessation of negative feedback signals from the gonads. The genital glands could act either directly or indirectly via the brain.

Effects of sodium chloride on the hydraulic conductivity of soybean root systems.

Root system hydraulic conductivity (L(P)) was measured on soybean (Glycine max [L.] Merr. var Harosoy) seedlings grown in solution culture and exposed to varying levels of osmotic stress. Hydroponic growth solutions were salinized by additions of NaCl, and the permeability of excised seedling root systems to water was measured. Conductance was estimated at high rates of water flux, where osmotic effects are negligible. L(P) was reduced as the salinity of the growth solution increased. Growth in NaCl for 14 days at -0.17 megapascals and -0.26 megapascals resulted in reductions in L(P) from that of controls by 27% and 72%, respectively. L(P) was correlated with the root/shoot biomass ratio (RS), with larger values of L(P) observed in seedlings with lower RS.

Effect of brain electrostimulation on antennal regeneration in Lithobius forficatus L. (Myriapoda:Chilopoda). Preliminary note.

After the antennae of Lithobius forficatus were amputated, electrical stimulation of the deutocerebral apex (= antennal lobes) either in the spring or the autumn led to (1) a decrease in the number of regenerated articles, and (2) an increase in the time-lag between the experiment and moulting. Moreover, in the spring experiments, the antennae regenerated asymmetrically. The electrostimulatory effect could act through an endocrine centre, probably the cerebral glands.

Net CO(2) assimilation of cacao seedlings following dark chilling.

Overnight exposure of cacao (Theobroma cacao L.) seedlings to chilling temperatures between 4.7 and 15.8 degrees C reduced net CO(2) assimilation rate (A) and stomatal conductance to water vapor (g(s)), with temperatures below 10 degrees C causing severe inhibition. Net CO(2) assimilation rates of chilled seedlings recovered to those of nonchilled plants within 7 days. No differences in daytime intercellular CO(2) concentration (c(i)) with overnight temperature were observed on the first day after the chilling treatment, which indicates that the reduction in photosynthesis was not caused by the reduction in stomatal conductance. However, c(i) of chilled plants was much less than that of nonchilled plants on the second day after treatment, which suggests that chilling caused a change in stomatal response to CO(2) concentration. Even 7 days after treatment, when A had recovered to control values, g(s) of chilled leaves was only approximately 70% that of controls. Chilling did not inhibit A through an effect on leaf water potential, which was higher in chilled plants than in unchilled plants.

Net CO2 assimilation of cacao seedlings during periods of plant water deficit.

The effect of leaf water potential (Ψ) on net CO2 assimilation rate (A), stomatal conductance (g), transpiration (E) and water-use efficiency (WUE) was measured for three cultivars of cacao (Theobroma cacao L.) seedlings during three recurrent drought cycles. Net assimilation varied greatly at high water potentials, but as Ψ dropped below approximately -0.8 and -1.0 MPa, A was reduced to less than 1.5 µmol CO2 m(-2) s(-1). The relation between g and A was highly significant and conformed to an asymptotic exponential model, with A approaching maximal values at stomatal conductances of 55-65 mmol H2O m(-2) s(-1). Net assimilation varied linearly (r=0.95) with transpiration, and the slope of the A-E relation (WUE) was approximately 3.0 µmol CO2 mmol(-1) H2O throughout the range of stomatal conductances observed. C i was insensitive to water stress, even though both g and A were strongly affected. Under the experimental conditions used here, mesophyll photosynthesis did not appear to control g through changes in C i. As stress intensified within each drying cycle, WUE of nonirrigated seedlings did not decline relative to that of controls even though CO2 and water vapor exchange rates underwent large displacements. The effect of seed source was highly significant for WUE, and the basis for observed differences among genotypes is discussed.

Alteration of Cell-Wall Water Content and Elasticity in Douglas-Fir during Periods of Water Deficit.

Three populations of seedlings of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) were subjected to recurrent drought cycles. Pressure-volume curves were developed to derive the osmotic and pressure potentials as functions of the symplastic water over a wide range of relative water content. The drought cycles induced large reversible changes in the relative water content of the apoplasm and in the bulk modulus of elasticity. These responses have not been reported previously in any species of higher plant. Our data suggest that turgor regulation in Douglas-fir is mediated by structural and biochemical factors associated with the cell wall, rather than by osmotic adjustment.

Intracanopy lighting reduces electrical energy utilization by closed cowpea stands.

The high planting densities needed to grow edible biomass in sustainable space life support systems will create problems for planophile crops that form closed, self-shading canopies. The use of traditional overhead-lighting configurations will reduce the penetration of photosynthetically active radiation (PAR) into such canopies and will result in substantial shading of understory leaves. Intracanopy lighting, an irradiation approach that allows plants to grow around fixed arrays of low-intensity lamps, reduces overall energy expenditure for crop production by improving light distribution and interception throughout the canopy. Comparing different fluorescent lamp geometries within vegetative canopies of cowpea (Vigna unguiculata L. Walp) revealed great plasticity of leaf orientation to maximize absorption of PAR from lamps arrayed at various nontraditional angles. Varying the amount of photosynthetic energy available within canopies creates considerable potential to manipulate canopy productivity. Increasing lamp number 38% within cowpea canopies raised stand productivity 45%, reflecting the highly efficient interception and absorption of intracanopy PAR. However, combined above/within-canopy lighting did not increase overall PAR interception and vegetative yield, and productivity did not improve relative to the same input wattage of intracanopy lighting alone. Optimization of intracanopy lighting for crops to be used in future space life support systems will substantially reduce power and energy burdens for food-crop production.

Overview on the pharmacokinetics of tenoxicam.

Tenoxicam, a new non-steroidal anti-inflammatory drug (NSAID) with an oxicam structure, is entirely ionised at physiological pH, has minimal lipophilic properties, high plasma protein binding, does not accumulate in fatty tissue and skin and thus has a small volume of distribution. Tenoxicam is rapidly and completely absorbed after oral administration. It is entirely metabolised via oxidation and conjugation pathways before elimination. The extraction ratio in the liver is small resulting in a long elimination half-life with a mean of 72 hours. Since no unchanged drug is found in the bile the low half-life cannot be explained by enterohepatic recirculation of parent compound. The low elimination rate of tenoxicam allows for a once-daily dosage (20 mg) regimen. Following multiple dosing during the first two weeks of therapy tenoxicam reaches steady-state levels within 10-20% of predicted values. Several pharmacokinetic factors help make tenoxicam therapy safe and straightforward: it is completely absorbed when taken orally even with meals or antacids, it penetrates easily into synovial fluid, and is excreted as inactive metabolites. Furthermore, drug disposition is not influenced by age, sex or rheumatic disease and unexpected accumulation is not observed.

[Osteoporosis at high remodeling and parathyroid function. Histo-biological confrontations (author's transl)]. / Ostéoporoses à haut niveau de remodelage et fonction parathyroïdienne. Confrontations histo-biologiques.

In order to evaluate the relationship between apparently idiopathic osteoporosis and parathyroid hormone secretion, plasma immunoreactive parathyroid hormone (iPTH) was measured in 57 untreated osteoporotic patients using a carboxyl-terminal specific antiserum, and sections of undecalcified iliac bone biopsies from these subjects, who had been previously doubly labelled with tetracycline, were quantitatively analysed. Twenty-one patients (36%) exhibited histological signs of a high remodeling similar to that which is present in primary hyperparathyroidism, but their osteoplastic appositional rate values were lower. Among these 21 cases 8 had an increase of their iPTH levels. These data and those of the literature indicate that in a few cases high remodeling osteoporosis may be associated with parathyroid hypersecretion, but do not bring out the evidence that the increased circulating iPTH is the cause of osteoporosis. The authors draw from their results some practical consequences for the treatment of high remodeling osteoporosis.

[Osteoporosis at high remodeling and parathyroid function. Histo-biological confrontations (author's transl)]. / Ostéoporoses .a haut niveau de remodelage et fonction parathyroïdienne. Confrontations histo-biologiques.

In order to evaluate the relationship between apparently idiopathic osteoporosis and parathyroid hormone secretion, plasma immunoreactive parathyroid hormone (iPTH) was measured in 57 untreated osteoporotic patients using a carboxy-terminal specific antiserum, and sections of undecalcified iliac bone biopsies from these subjects, who had been previously doubly labelled with tetracycline, were quantitatively analyzed. Twenty one patients (36%) exhibited histological signs of a high remodeling similar to that which is present in primary hyperparathyroidism, but their osteoplastic oppositional rate values were lower. Among these 21 cases 8 had an increase of their iPTH levels. These data and those of the literature indicate that in a few cases high remodeling osteoporosis may be associated with parathyroid hypersecretion, but do not bring out the evidence that the increased circulating iPTH is the cause of osteoporosis. The authors draw from their results some practical consequences for the treatment of high remodeling osteoporosis.