Tree root dynamics in montane and sub-alpine mixed forest patches

BACKGROUND AND AIMS

The structure of heterogeneous forests has consequences for their biophysical environment. Variations in the local climate significantly affect tree physiological processes. We hypothesize that forest structure also alters tree root elongation and longevity through temporal and spatial variations in soil temperature and water potential.

METHODS

We installed rhizotrons in paired vegetation communities of closed forest (tree islands) and open patches (canopy gaps), along a soil temperature gradient (elevations of 1400, 1700 and 2000 m) in a heterogeneous mixed forest. We measured the number of growing tree roots, elongation and mortality every month over 4 years.

KEY RESULTS

The results showed that the mean daily root elongation rate (RER) was not correlated with soil water potential but was significantly and positively correlated with soil temperature between 0 and 8 °C only. The RER peaked in spring, and a smaller peak was usually observed in the autumn. Root longevity was dependent on altitude and the season in which roots were initiated, and root diameter was a significant factor explaining much of the variability observed. The finest roots usually grew faster and had a higher risk of mortality in gaps than in closed forest. At 2000 m, the finest roots had a higher risk of mortality compared with the lower altitudes.

CONCLUSIONS

The RER was largely driven by soil temperature and was lower in cold soils. At the treeline, ephemeral fine roots were more numerous, probably in order to compensate for the shorter growing season. Differences in soil climate and root dynamics between gaps and closed forest were marked at 1400 and 1700 m, but not at 2000 m, where canopy cover was more sparse. Therefore, heterogeneous forest structure and situation play a significant role in determining root demography in temperate, montane forests, mostly through impacts on soil temperature.

CFD simulation of fluid dynamic and biokinetic processes within activated sludge reactors under intermittent aeration regime

Due to the aeration system, biological reactors are the most energy-consuming facilities of convectional WWTPs. Many biological reactors work under intermittent aeration regime; the optimization of the aeration process (air diffuser layout, air flow rate per diffuser, aeration length …) is necessary to ensure an efficient performance; satisfying the effluent requirements with the minimum energy consumption. This work develops a CFD modelling of an activated sludge reactor (ASR) which works under intermittent aeration regime. The model considers the fluid dynamic and biological processes within the ASR. The biological simulation, which is transient, takes into account the intermittent aeration regime. The CFD modelling is employed for the selection of the aeration system of an ASR. Two different aeration configurations are simulated. The model evaluates the aeration power consumption necessary to satisfy the effluent requirements. An improvement of 2.8% in terms of energy consumption is achieved by modifying the air diffuser layout. An analysis of the influence of the air flow rate per diffuser on the ASR performance is carried out. The results show a reduction of 14.5% in the energy consumption of the aeration system when the air flow rate per diffuser is reduced. The model provides an insight into the aeration inefficiencies produced within ASRs.

Cryopreservation of seeds and in vitro-cultured protocorms of Oncidium bifolium sims. (Orchidaceae) by encapsulation-dehydration

Encapsulation-dehydration was employed for cryopreserving seeds and in vitro-cultured protocorms of Oncidium bifolium. Freshly harvested seeds, 120 days after pollination, were encapsulated in beads containing 1/2 MS medium with 3% sucrose and 3% calcium alginate and subsequently pretreated in agitated (80 rpm) liquid medium supplemented with 0.15 M sucrose (24 h) followed by 0.25 M sucrose (48 h), 0.5 M sucrose (24 h) and 0.75 M sucrose (24 h). The beads with seeds were dehydrated with silica gel for 5 h to 19.2% moisture content and immersed in liquid nitrogen for 1 h, thawed at 30 degrees C for 2 min, post-treated using the same series of liquid media [0.5 M sucrose (24 h), 0.25 M sucrose (48 h), 0.15 M sucrose (24 h)], and recultured on 1/2 MS medium with 0.1M sucrose and 0.7% percent agar. As much as 4.8% of the cryopreserved seeds produced complete plants. In-vitro cultured protocorms were successfully cryopreserved following the same procedure, allowing 11.3% of them to produce plants.

Plant regeneration of Ilex paraguariensis (Aquifoliaceae) by in vitro culture of nodal segments

In vitro regeneration of complete plants from nodal single bud segments of "yerba mate" (Ilex paraguariensis St. Hil.) was studied under defined nutritional and environmental conditions. Nodal segments harvested from actively growing shoots of conventionally raised plants were cultured on nutrient medium with the mineral salts and vitamins of Murashige and Skoog medium at 1/4 strength, supplemented with various concentrations of sucrose and 6-benzyladenine (BAP). Shoot regeneration from explants of both young (2 years old) and adult (20 years old) mother plants were readily achieved in the medium supplemented with 0.04-0.09 M sucrose with or without BAP. As many as 60-65% of the nodal segments cultured formed shoots. Rooting of regenerated shoots was observed in 50% of the explants harvested from young plants, whereas 25% of the explants rooted when the nodal explants were harvested from adult plants. The best rooting induction was achieved on 1/4 strength MS medium with vermiculite as the substrate and supplemented with 1-1.5% IBA (indolebutyric acid) and 1-2% PPZ (3-methyl-1-phenyl-2 pyrazolin-5-one). Plantlets were successfully transferred to soil.

Development of matrix-based theophylline sustained-release microtablets

Microtablets containing high theophylline content (from 60% to 80%) based on a Eudragit RS PO matrix were produced on a rotary tablet press. The influence of the compaction pressure, the plasticizer content used for the granulation of theophylline particles, and the amount of theophylline on the drug release were investigated. The effects of surface area and the addition of magnesium stearate as a hydrophobic agent on the drug release were studied. The storage stabilities of the release rate at room temperature and at 50 degrees C were also determined. Dissolution profiles expressed as percentage of theophylline dissolved were obtained over 8 hr in 900 ml of purified water at 37 degrees C and 75 rpm. It was observed that the compaction pressure (from 200 MPa to 250 MPa) had no effect on the theophylline release. The use of triethyl citrate (TEC) as a plasticizer in the granulation of theophylline enhanced the physical properties of the microtablets. Theophylline content in the range 60% to 80% did not affect the drug release. The theophylline release obtained was a function of the quotient surface area/tablet weight and therefore was dependent on the tablet diameter. To reduce the dissolution rates, magnesium stearate was added in a concentration up to 50% of the matrix material. Tablets of this hydrophobic formulation fulfilled the requirements of USP 23 for theophylline sustained-release preparations. Storage at room temperature for 3 months and at 50 degrees C for 2 months showed no significant influence on the theophylline release.

Typology and correlates of sexual abuse in children and youth: multivariate analyses in a prevalence study in Geneva

OBJECTIVE

Child sexual abuse (CSA) encompasses a variety of distinct situations, which should be differentiated. There is a need for a working classification, taking into account various parameters.

METHODS

The Geneva CSA prevalence study was based on 1116 randomly selected adolescents aged 14 to 16. Secondary analyses of the 252 reported cases of abuse was carried out using a multivariate approach combining multiple correspondence analysis and automatic classification, leading to descriptive analyses and to a new classification of CSA.

RESULTS

Global prevalence of CSA, using a broad definition, was 10.9% for boys, and 33.8% for girls. Classification of cases of abuse differentiated 5 classes: (A) exhibitionism or other abuse without contact, by an adult (proportion of cases in boys: 22%; girls: 32%); (B) abuse of an adolescent boy by a peer without contact (62%); (C) abuse of an adolescent girl by a peer with physical contact (38%); (D) abuse inside the family, repeated (boys: 10%, girls: 16%); (E) child abuse with genital penetration, lasting 2 years or more (boys: 7%; girls: 14%).

CONCLUSIONS

CSA is a complex and heterogeneous problem. Reported abuse situations can be classified into five classes, with different degrees of severity, causes, and consequences. Classification is essential in clinical research as well as in the design and conception of prevention programs.

Birth-related fatigue in 34-36-week preterm neonates: rapid recovery with very early kangaroo (skin-to-skin) care

OBJECTIVE

To test preterm neonates' physiologic and behavioral responses when placed skin-to-skin on their mother's chests, called kangaroo care (KC), for the first 6 hours after birth, instead of having the neonates go to an intensive care unit.

DESIGN

Convenience sampling was used in this descriptive study to enroll neonates who were given continuous KC beginning soon after birth in the delivery room and continuing for 6 hours. Heart rate, respiratory rate, oxygen saturation, abdominal temperature, and behavioral state were recorded each minute.

SETTING

Data were collected in the delivery room and in a private labor room in tropical Cali, Colombia.

PARTICIPANTS

Six 34-36-week preterm neonates with 5-minute APGAR scores of 6 or more were enrolled. Two neonates had grunting respirations before KC was begun.

RESULTS

Temperature rose rapidly to thermoneutral range. With few exceptions, heart rate, respiratory rate, and oxygen saturation remained within normal limits; grunting respirations in two neonates disappeared with warmed humidified oxygen and continuous KC. Sleep predominated, and neonates were discharged home by 48 hours being fully breastfed, suggesting that KC was an environment conducive to recovery from fatigue.

CONCLUSIONS

These data suggest that KC beginning in the delivery room can be given safely and perhaps with benefit to 34-36-week gestation neonates who appear healthy at birth. Kangaroo care was conducive to recovery from birth-related fatigue.

Enzymatic activity of two caspases related to interleukin-1beta-converting enzyme

Interleukin-1beta-converting enzyme is a member of a family of human cysteine proteases with specificity for aspartic acid, which have been named caspases. Within this family of enzymes, transcript X (TX) and transcript Y (TY) (caspases 4 and 5, respectively) are very similar to ICE (caspase 1) and form the ICE subfamily. Given the high degree of conservation in the sequences of these proteases (more than 50% amino acid identity in the mature enzymes), it was of interest to examine whether they shared similar substrate specificities. The three enzymes, ICE, TX and TY, were therefore expressed in baculovirus-infected insect cells, as 30-kDa proteins lacking the propeptide. Automaturation into p20 and p10 subunits occurred within the cells. Active ICE, TX and TY were collected in the cell culture supernatants. In addition, their production induced the activation of an endogenous 32-kDa putative cysteine protease (CPP32) like caspase. T7-tagged ICE, TX and TY were purified by immunoaffinity and tested for their catalytic efficiency on YVAD-containing synthetic substrates and on the ICE natural substrate, pro-interleukin-1beta. TX cleaved the same synthetic substrates as ICE (Km of 90 microM and k(cat) of 0.4 s(-1) for Suc-YVAD-NH-Mec, where Suc represents succinyl and NH-Mec represents amino-4-methylcoumarin) and could cleave pro-interleukin-1beta into the same peptides as ICE but less efficiently. On the other hand, TY showed very little efficacy on the different ICE substrates (Km of 860 microM for Suc-YVAD-NH-Mec). These results show that the ICE/TX/TY subfamily has functional heterogeneity and that ICE remains the preferred enzyme for pro-interleukin-1beta cleavage.

Drop-out reasons and complications in self-injection therapy with a triple vasoactive drug mixture in sexual erectile dysfunction

The usefulness, complications and reasons for discontinuing the self-injection program with a combination of papaverine, phentolamine and prostaglandin E1 were evaluated in 189 patients (mean age 57.2 y), who were included from April 1993 to September 1995 (mean follow-up 10.25 months). Patients were split into two groups: Active, those who continued with the program (48%); and Inactive, those who discontinued treatment or failed to attend consultation after five months from the last visit (52%). Only 30% of the inactive group reported failure to achieve response with the self-injected doses. Fibrosis in 5.3% and prolonged erection in 3.7% were the most severe complications. Patients lacking organic pathology showed a clear tendency to reduce the drug dose during treatment, recover spontaneous erections and discontinue the program for reasons unrelated to drug efficacy. The triple drug mixture provides an effective alternative in the treatment of impotence, with a low rate of complications.

Comparative study of papaverine plus phentolamine versus prostaglandin E1 in erectile dysfunction

PURPOSE

We compared the efficacy and short-term adverse effects of 1 ml. 30 mg./ml. papaverine plus 0.5 mg./ml. phentolamine versus 1 ml. 30 micrograms./ml. prostaglandin E1 in patients undergoing pharmacological erection testing.

MATERIALS AND METHODS

A total of 60 patients (mean age 58 years) with a history of sexual erectile dysfunction longer than 6 months was randomly classified into 6 groups to be tested 1 week apart with the 2 solutions and with placebo to evaluate erection response and short-term adverse effects.

RESULTS

Of the patients tested with papaverine plus phentolamine 54% responded with erections adequate for penetration, compared to 50% of those tested with prostaglandin E1 (p > 0.05). Prolonged erection occurred in 18% of patients tested with papaverine plus phentolamine and 15% of those tested with prostaglandin E1 (p > 0.05). Pain was reported by 15 and 35% of patients, respectively (p < 0.05).

CONCLUSIONS

One ml. 30 mg./ml. papaverine plus 0.5 mg./ml. phentolamine has the same efficacy and equal prolonged erection rate as 1 ml. 30 micrograms./ml. prostaglandin E1 but the latter agent induces significantly more pain.

[Mitomycin C for the treatment of superficial tumors of the bladder (Tis-Ta-T1) with one or more risk factors. Argentinian Cooperative Group of Oncourology (GCAO)]

OBJECTIVES

To determine the efficacy and toxicity of intravesical mitomycin C in superficial bladder tumors (Tis Ta T1) completely resected with one or more risk factors. (Protocol U. 01/90).

METHODS

The patients received six instillations weekly of 40 mg mitomycin C within 15 days post-TUR of a superficial bladder tumor with one or more risk factors: histological grade 3, tumor size more than 3 cm and/or multicentric lesion. The patients were evaluated by cystoscopy every three months for the first two years and every six months thereafter. Toxicity was evaluated according to Miller's score. Tumor recurrence, disease-free interval and survival were analyzed.

RESULTS

126 patients were entered into the study; of these, 110 were evaluable. At 18 months mean follow-up (range 6-36 months), 77 patients (70%) remain disease-free; the mean time to recurrence was 13.8 months. There were no differences between patients with one, two or three risk factors or those who received or did not receive previous treatments. The patients tolerated the treatment well; there were no dropouts or systemic toxicity.

CONCLUSIONS

1. At 18 months mean follow-up, 77 of 110 patients (70%) remain disease-free; 2. The mean time to recurrence was 13.8 months; 3. Local toxicity was minimal; 4. There were no dropouts due to toxicity; 5. Systemic toxicity was not observed.

Calcium-independent regulation of pigment granule aggregation and dispersion in teleost retinal pigment epithelial cells

In the eyes of teleosts and amphibians, melanin pigment granules of the retinal pigment epithelium (RPE) migrate in response to changes in light conditions. In the light, pigment granules disperse into the cells' long apical projections, thereby shielding the rod photoreceptor outer segments and reducing their extent of bleach. In darkness, pigment granules aggregate towards the base of the RPE cells. In vitro, RPE pigment granule aggregation can be induced by application of nonderivatized cAMP, and pigment granule dispersion can be induced by cAMP washout. In previous studies based on RPE-retina co-cultures, extracellular calcium was found to influence pigment granule migration. To examine the role of calcium in regulation of RPE pigment granule migration in the absence of retinal influences, we have used isolated RPE sheets and dissociated, cultured RPE cells. Under these conditions depletion of extracellular or intracellular calcium ([Ca2+]o, [Ca2+]i) had no effect on RPE pigment granule aggregation or dispersion. Using the intracellular calcium dye fura-2 and a new dye, fura-pe3, to monitor calcium dynamics in isolated RPE cells, we found that [Ca2+]i did not change from basal levels when pigment granule aggregation was triggered by cAMP, or dispersion was triggered by cAMP washout. Also, no change in [Ca2+]i was detected when dispersion was triggered by cAMP washout in the presence of 10 microM dopamine, a treatment previously shown to enhance dispersion. In addition, elevation of [Ca2+]i by addition of ionomycin neither triggered pigment movements, nor interfered with pigment granule motility elicited by cAMP addition or washout. Since other studies have indicated that actin plays a role in both pigment granule dispersion and aggregation in RPE, our findings suggest that RPE pigment granule migration depends on an actin-based motility system that is not directly regulated by calcium.

Retinomotor movements in isolated teleost retinal cone inner-outer segment preparations (CIS-COS): effects of light, dark and dopamine

Teleost cone inner segments elongate and contract in response to light and circadian signals. Previous studies have shown that teleost cone contraction is triggered by light or dopamine, while cone elongation is triggered by darkness or experimental elevation of cAMP. We have developed procedures for isolating and purifying motile cone fragments consisting of inner and outer segments (CIS-COS) to permit more detailed analysis of light and dopamine regulation of cone retinomotor movements. When retinas are dissected from long-term dark-adapted fish, CIS-COS break off at the base of the ellipsoid and remain attached to the RPE. CIS-COS can be detached from the RPE by brief protease treatment, thereby generating a highly enriched CIS-COS suspension. CIS-COS retain normal morphology and extend new myoids when cultured in darkness or in light plus forskolin, an activator of adenylate cyclase. The microtubule and actin cytoskeletons of the new myoids resemble those of intact cone myoids in vivo. Light inhibits CIS-COS myoid elongation, suggesting that light reception by the outer segment can directly influence cone motility. In dark-cultured CIS-COS, myoid elongation is inhibited half-maximally by nanomolar concentrations of dopamine, suggesting that dopamine effects on motility are mediated by D2-family receptors present on the cone inner and/or outer segment. After dark-induced elongation in culture, CIS-COS myoids can be induced to contract by subsequent culture in the light or with dopamine. Thus isolated cone inner and outer segments possess sufficient cytoskeletal and regulatory machinery to exhibit light- and dopamine-regulation retinomotor movement similar to that observed in intact cones in situ.

Skin-to-skin contact beginning in the delivery room for Colombian mothers and their preterm infants

To determine if the transition to extrauterine life is facilitated by skin-to-skin contact, six relatively low risk preterm infants experienced six continuous hours of skin-to-skin contact on their mothers' chests beginning within 30 minutes of birth. Heart and respiratory rates and oxygen saturation remained within normal limits and all infant temperatures rose rapidly to thermoneutral range. Two infants developed grunting respirations by the time skin-to-skin contact began, but the grunting disappeared with warm, humidified oxygen and continuous skin-to-skin contact. All infants were fully breastfeeding and ready for discharge by 24-48 hours postbirth. Early skin-to-skin contact was safe and seemed beneficial for these relatively low risk preterm infants.

Selected physiologic measures and behavior during paternal skin contact with Colombian preterm infants

A descriptive study of eleven healthy preterm infants was conducted in which cardiorespiratory (heart and respiratory rates, oxygen saturation), thermal (abdominal, toe and tympanic temperatures) and state behavior responses to two hours of paternal skin-to-skin contact within the first 17 hours of birth in Colombia, South America were evaluated. Infant physiologic and behavioral state measures were recorded each minute as was paternal skin temperature and behavior. Infant heart and respiratory rates increased during paternal contact as did abdominal and core temperatures. Fathers were able to keep their infants sufficiently warm, and five infants became hyperthermic (tympanic temperature greater than 37.5 degrees C) despite cooling measures while being held in this climate. Infants slept most of the time while being held and fathers seldom gazed at, spoke to, or touched their infants while holding them. When mothers are unavailable, fathers may be an alternate source of warmth and comfort to infants.

Chronic instrumentation and longterm investigation in the fetal and maternal baboon: tether system, conditioning procedures and surgical techniques

A tether system, conditioning procedures and surgical techniques were designed to maintain chronic catheters and electrodes in the pregnant baboon and her fetus. The tether system was comprised of a lightweight metal backpack containing catheters and electrodes, couplers, pressure transducers and electrical cabling. The backpack was held snugly in place by shoulder and body straps. A flexible metal tether connected the pack to a ball bearing assembly mounted on the top of the animal's home cage. Attached to the assembly were two infusion pumps, fluid reservoir and slip ring electrical connector. The entire system rotated freely with the movements of the animal; thus, the instrumentation and connectors were secure while access was maintained for continuous physiologic recording and intravascular infusion or intermittent blood sampling with minimal physical restraint. Animals were conditioned to accept the system prior to pregnancy and animals who demonstrated tolerance were bred. An initial group of 10 pregnant animals were sham tethered during pregnancy at 102 +/- 7 days with term gestation estimated at 180 days. Surgical procedures were done at 136 +/- 4 days with placement of catheters in the maternal femoral artery and vein, fetal carotid artery jugular vein and trachea, amniotic fluid cavity, and electrodes for fetal electrocardiogram and electroencephalogram. The mean fetal survival time was 9.3 (range 0 to 29) days. The major complications which led to early delivery were placental abruption and rupture of amniotic membranes. With ultrasonic localization of the placenta and determination of fetal position before surgery, these complications may be avoided.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunological sequelae of intrauterine infection

Compared to normal children, pre-natally infected infants had significantly elevated IgM concentrations throughout the first year of life and elevated IgA levels for the first 6 months. In contrast, IgG levels dropped significantly below normal at 3 months post-partum. Infants born without overt disease but with elevated IgM were found to have precocious development of serum IgA when compared to control children. Levels of IgA and IgG in tears were markedly reduced in symptomatic children at 3 months of age. Lymphocyte response in vitro to phytohaemagglutinin and pokeweed mitogen was low in symptomatic infants. These results suggest that intratuerine infection may result in multiple immunological abnormalities.

Development of impaired cell-mediated immunity in mild and moderate malnutrition

The development of moderate malnutrition and cell-mediated immune function was studied in 71 Colombian infants from birth through 2 yr of age. Based upon weight-for-age criteria 31 remained normal, 33 were classified as grade I, and seven were grade II malnourished at the end of their 2nd yr of life. Delayed hypersensitivity reactions to purified protein derivative were significantly reduced in all malnourished children 8 wk after Bacille Calmette-Guerin vaccination at birth, and also at 2 yr in the Grade II group. Nearly half of the latter group could not be sensitized to dinitrochlorobenzene at 2 yr of age. A 50% reduction in the blastogenic response of peripheral blood lymphocytes to phytohemagglutinin in vitro was detected in grade II children. Both mildly and moderately malnourished infants exhibited a significant reduction in tonsil size at 2 yr of age. These results indicate that a majority of newborns in this poor, urban setting will develop measurable malnutrition associated with impaired cell-mediated immune function before their 2nd birthday.

Effect of moderate malnutrition on concentrations of immunoglobulins and enzymes in tears and saliva of young Colombian children

The influence of moderate malnutrition on immunoglobulins and enzymes in the sera and secretions of 71 Colombian children was studied. Concentrations of immunoglobulin A, immunoglobulin G, lysozyme, albumin, and aminopeptidase were measured in the sera, tears, and saliva of 27 normal, 32 grade I, 9 grade II, and 3 grade III malnourished children. The most severely malnourished children, grades II and III, had markedly reduced immunoglobulin A concentrations and elevated immunoglobulin G concentrations in tears. Immunoglobulin A levels in whole saliva were also reduced in these malnourished children. In contrast, the concentration of immunoglobulin A in the sera of these children was significantly elevated. There was no influence of malnutrition on levels of lysozyme, albumin, total protein, and aminopeptidase in tears or saliva. These results indicate that secretory immunity may be impaired in moderately malnourished children due to decreased levels of immunoglobulin A in secretions.

[Results of ortho- and megavolt therapy of inoperable bronchial carcinoma]

Survival rates of patients with inoperable, histologically verified bronchial carcinoma are compared as to orthovoltage or megavoltage radiation therapy. With megavoltage therapy, better survival rates are obtained after one or two years; later on, an approximation of the comparison groups is to be observed with regard to life expectancy. The improvement in one-year and two-year survival rates does justify the application of megavoltage therapy.