Climate change may restrict dryland forest regeneration in the 21st century.

The persistence and geographic expansion of dryland forests in the 21st century will be influenced by how climate change supports the demographic processes associated with tree regeneration. Yet, the way that climate change may alter regeneration is unclear. We developed a quantitative framework that estimates forest regeneration potential (RP) as a function of key environmental conditions for ponderosa pine, a key dryland forest species. We integrated meteorological data and climate projections for 47 ponderosa pine forest sites across the western United States, and evaluated RP using an ecosystem water balance model. Our primary goal was to contrast conditions supporting regeneration among historical, mid-21st century and late-21st century time frames. Future climatic conditions supported 50% higher RP in 2020-2059 relative to 1910-2014. As temperatures increased more substantially in 2060-2099, seedling survival decreased, RP declined by 50%, and the frequency of years with very low RP increased from 25% to 58%. Thus, climate change may initially support higher RP and increase the likelihood of successful regeneration events, yet will ultimately reduce average RP and the frequency of years with moderate climate support of regeneration. Our results suggest that climate change alone may begin to restrict the persistence and expansion of dryland forests by limiting seedling survival in the late 21st century.

Comparison of cognitive function after carotid artery stenting versus carotid endarterectomy.

The effect of carotid artery stenting (CAS) and carotid endarterectomy (CEA) on cognitive function is unclear. Both cognitive improvement and decline have been reported after CAS and CEA. We aimed to compare the changes in postprocedural cognitive function after CAS versus CEA. A systematic qualitative review of the literature was conducted according to the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-analysis statement for studies evaluating the changes in cognitive function after CAS compared with CEA. Thirteen studies (403 CEAs; 368 CAS procedures) comparing the changes in cognitive function after CEA versus CAS were identified. Most studies did not show significant differences in overall cognitive function or only showed a difference in a single cognitive test between the two procedures. A definitive conclusion regarding the effect of CAS versus CEA on cognitive function was not possible owing to heterogeneity in definition, method, timing of assessment, and type of cognitive tests. For the same reasons, performing a meta-analysis was not feasible. The lack of standardization of specific cognitive tests and timing of assessment of cognitive function after CAS and CEA do not allow for definite conclusions to be drawn. Larger, adequately-powered and appropriately designed studies are required to accurately evaluate the effect of CAS versus CEA on postprocedural cognitive function.

Emotional distress and health risk behaviours of mothers of United States Marines.

AIM: The aim was to explore emotional distress and health risk behaviours of mothers of servicemen. The study was inspired by the first author's clinical practice in primary care among women who reported significant emotional distress surrounding impending deployment of their sons. BACKGROUND: Thousands of US service members have been deployed in the current wars. The potentially profound effects of deployment on emotional distress of military spouses and children have been documented; however, mothers of servicemen have not been studied. METHODS: This was an exploratory descriptive study to determine self-reported levels of emotional distress and health risk behaviours in the mothers of deployed male US Marines compared with mothers of male Marines not currently deployed. Mothers were accessed via a voluntary online support organization. RESULTS: Mothers of deployed sons reported significantly higher levels of emotional distress and more health risk behaviours compared with mothers of sons not deployed. Many of the mothers in both groups reported high levels of emotional distress. DISCUSSION: As primary care providers, nurses should be alert to the high levels of emotional distress and health risk behaviours among all patients. This exploratory study highlights these dimensions in mothers of servicemen. CONCLUSIONS: This study is the first of mothers of sons serving in the military. While the focus is on mothers of sons serving in the US military, their experience is likely not unique. Mothers of military service members all over the world send their children off to war and wait for their safe return.

Measurement differences between three versus five photocells during collection of ground reaction forces in dogs.

The differences between velocities and accelerations obtained from three and five photocells were examined when obtaining ground reaction force (GRF) data in dogs. Ground reaction force data was collected 259 times from 16 different dogs in two experimental phases. The first phase compared velocities and accelerations reported by the two systems based on trials accepted by the three photocell system. The second phase accepted trials based on data from five photocells. Three photocell data were calculated mathematically in the second phase in order to compare the values of both systems. The velocity and acceleration values obtained from each system were significantly different (at the hundredth of a meter per second). Differences in measured values did not result in acceptance of data by the three photocell system that would not have been acceptable with the five photocell system (false positives), but did result in rejection of acceptable data by the three photocell system (11% false negative rate). Given the small differences between the two systems, GRF data collected should not be significantly different, though the three photocell system is less efficient in gathering data due to the number of trials rejected as false negatives.

Measurement of velocity with a kinematic system versus a photocell system in the collection of canine ground reaction forces.

Velocities obtained from a five photocell system were compared to velocities of nine anatomical points on a handler and canine subject as reported by a kinematic system over the same distance. There was not a statistically significant difference between the velocities of the markers on the dogs' occipital protuberance and interscapular region compared with the velocity as reported by the photocell system. The average velocities of the three markers on the forelimb of the dogs and three markers on the handler's leg and one on the sacrum had statistically different values than the photocell system. Given these results, photocell systems with the same configuration in this study can be trusted to report accurate trunk velocities of canine subjects during the collection of ground reaction forces.

Effects of cocaine on extracellular dopamine and serotonin levels in the nucleus accumbens.

RATIONALE: Although the rewarding effects of cocaine are generally attributed to its ability to increase dopamine (DA) transmission, cocaine demonstrates approximately equal affinity for dopamine and serotonin (5-HT) transporters in vitro. However, there have been few direct systematic comparisons of the effects of cocaine on DA and 5-HT transmission in vivo. OBJECTIVES: The present experiments compared the effects of systemic cocaine administration, local cocaine infusion and the systemic administration of cocaine during infusion on extracellular levels of DA and 5-HT in the nucleus accumbens (NAc). METHODS: In vivo microdialysis in awake unrestrained rats was used to measure the effects of systemic administration and local infusion of cocaine on extracellular DA and 5-HT levels simultaneously in the NAc. RESULTS: Systemic cocaine (10-25 mg/kg, IP) dose-dependently increased DA and 5-HT levels, but the increase in DA was larger than for 5-HT at 18 mg/kg. Infusion of cocaine (0.1-10.0 mM) into the NAc increased both DA and 5-HT levels, but the effect on DA was larger than 5-HT at 0.1 and 3 mM cocaine. The influence of cocaine on DA and 5-HT somatodendritic autoreceptors was examined when cocaine (25 mg/kg) was administered systemically during cocaine infusion. The increase in DA and 5-HT levels during cocaine infusion was attenuated by the systemic injection of cocaine during cocaine infusion, but the decrease of 5-HT was greater than that for DA. CONCLUSIONS: Cocaine produced a larger impact on DA than 5-HT neurotransmission under specific conditions. A series of physiological mechanisms, i.e. terminal density, neurotransmitter interactions and somatodendritic regulation, are discussed as factors responsible for facilitating cocaine's effects on DA relative to 5-HT.

Immunization of merino ewes with a synthetic inhibin peptide or with preparations obtained from bovine and porcine follicular fluids by immunoaffinity chromatography result in different effects on ovulation rate and on plasma gonadotrophin concentrations.

Ewes were immunized with either a synthetic peptide (peptide 1-32) that has an amino acid sequence identity with the first 32 amino acids at the amino terminal of the alpha-subunit of porcine inhibin, or with bovine or porcine monoclonal antibody purified inhibin (bMPI and pMPI respectively), obtained by immunochromatography from follicular fluids. The peptide 1-32 was conjugated to albumin before use. Peptide 1-32 and bMPI increased ovulation rate and number of follicles (greater than or equal to 5 mm diameter). Although bMPI increased plasma FSH concentration the peptide did not. pMPI had no effect on ovarian activity but markedly elevated both plasma FSH and LH concentrations. The plasma LH concentration was lowered in ewes immunized with peptide 1-32. It appears, therefore, that ovulation rate can be increased following increased plasma FSH concentrations at luteolysis or in the absence of such an increase. Conversely, greatly increased plasma gonadotrophin concentrations at luteolysis (pMPI) were not followed by an increase in ovulation rate. Antibodies in the plasma of ewes immunized with peptide 1-32 and bMPI bound to iodinated synthetic human inhibin alpha-chain 6-30 peptide. The results suggest that ovulation rate is at least partly determined by intraovarian factors.

The dose-dependent effect of BHT (butylated hydroxytoluene) on vitamin K-dependent blood coagulation in rats.

Earlier studies have reported a reduction of vitamin K-dependent blood clotting factor activity and incidence of haemorrhagic death in rats fed butylated hydroxytoluene (BHT); however, the vitamin K status of the animals used in these studies was claimed to be inadequate. The aim of the study reported here was to determine the effect of BHT on vitamin K-dependent clotting factors in vitamin K-sufficient and vitamin K-supplemented rats. Rats given BHT (3000 mg/kg body weight) for up to 21 days, in a diet containing a minimum of 3 ppm vitamin K3 (six times the recommended requirement), showed decreased vitamin K-dependent blood clotting factor activities, demonstrated by increases in factor-specific clotting time assays. Clotting times were prolonged within 7 days, significantly increased within 14 days (P < 0.001) and maximally increased 5.5-fold at 21 days (P < 0.05). Supplementation with a further 250 ppm vitamin K3 reversed this effect. BHT did not increase prothrombin time (PT), the usual index of clotting. However, in a similar 14-day investigation, a small but significant increase in PT (up to 151%, P < 0.005) was seen within 7 days. Further vitamin K supplementation was incapable of reversing this effect completely. A similar trend was shown by activated partial thromboplastin time. The 1/51 dilution Thrombotest, a more sensitive indicator of vitamin K-dependent clotting factor activity in the rat, was significantly increased (more than four fold, P < 0.01) within 7 days. This increase was fully reversed by further vitamin K supplementation. Prolongation of Thrombotest time was significant at a BHT dose level of 600 mg/kg body weight per day and this could be reversed by further supplementation of only 3.0 ppm vitamin K. However, at dose levels of 125 mg BHT/kg body weight per day or less, no clotting defects were observed. These studies confirm that chronic administration of more than 600 mg BHT/kg/day to rats supplied with recommended amounts of vitamin K can depress clotting factors and precipitate haemorrhagic deaths. When further vitamin K is provided, these deaths could be prevented even though not all clotting abnormalities may be reversed. This study disapproves the proposal that BHT-related clotting factor defects are confined to rats of inadequate vitamin K status, but shows that such effects do not occur at dose levels lower than 600 mg/kg/day. The results further indicate that rats receiving a high dose of BHT have a higher vitamin K requirement than would otherwise be considered necessary. However, as BHT produces no clotting defects in these animals receiving an intake 1000 times the acceptable daily intake, such clotting effects are most unlikely to indicate a human safety problem for BHT.

An assessment of chloramphenicol and thiamphenicol in the induction of aplastic anaemia in the BALB/c mouse.

The potential of the antibiotics chloramphenicol succinate (CAPS) and thiamphenicol (TAP) to induce aplastic anaemia in the female BALB/c mouse was investigated. CAPS was administered at 2000 mg/kg, and TAP at 850 mg/kg, daily by gavage, for 17 days. At 1, 13, 22, 41, 98 and 179 days after the final dose of each antibiotic, mice (n = 4 or 5) were sampled for haematological examination and haematopoietic stem cell assays. Both CAPS and TAP induced significant reductions in red blood cell count, haematocrit and haemoglobin values at day 1 post dosing; counts of colony-forming units-erythroid and colony-forming units-granulocyte-macrophage, were similarly significantly decreased at this time. All these reduced parameters returned towards normal at days 13 and 22. At days 41, 98 and 179, results for all haematological values and stem cell assays in both CAPS- and TAP-treated mice compared with the controls; there was no evidence of a reduction in peripheral blood values or bone marrow parameters at the later sampling points, as would be expected in a developing or overt bone marrow aplasia. We therefore consider that the administration of CAPS and TAP, which have been associated with the development of aplastic anaemia in man, induce a reversible anaemia, but not a chronic bone marrow aplasia, when given at haemotoxic dose levels for 17 days in the BALB/c mouse.

Haemotoxicity of thiamphenicol in the BALB/c mouse and Wistar Hanover rat.

Chloramphenicol (CAP) is haemotoxic in man, inducing two forms of toxicity. First, a commonly-occurring, dose-related, reversible bone marrow depression, which develops during treatment. Second, a rarer aplastic anaemia (AA), developing after treatment, is irreversible, and often fatal. Thiamphenicol (TAP) was developed as a replacement for CAP; however, there are no toxicological investigations in the mouse or rat on the dose-related haemotoxicity of TAP, in repeat dose gavage studies. Therefore, we have conducted a comprehensive investigation in these species, administering TAP for 7-17 days, to define haematological changes. Female BALB/c mice were gavaged with TAP, daily for 7-17 days at 400-1500 mg/kg; female Wistar Hanover rats were dosed with TAP daily at 50-375 mg/kg for 9 or 10 days. Haematological changes were studied at 1, 7 and 14 days post-dosing. In mice at day 1, TAP caused decreases in RBC, HCT and Hb; reticulocytes and platelets were reduced; changes were dose-related and reversible. Marrow cell counts were reduced; marrow was hypocellular, with erythroid depletion and progenitor cell vacuolation; the myeloid/erythroid (M:E) ratio was increased. In the rat, changes were not as clear-cut; there was anaemia with indications of reduced reticulocyte and platelet counts, and evidence of decreased neutrophils and lymphocytes. Marrow erythroid cells were decreased, precursor cells vacuolated, and the M:E ratio increased. We conclude that TAP induced haematological changes in the mouse and rat, parallelling the dose-dependent, reversible marrow depression reported in man; TAP is more haemotoxic in the rat than in the mouse.

Ethanol drinking patterns in a continuous-access operant situation: effects of ethanol concentration and response requirements.

Rats, initiated to self-administer ethanol with either a sucrose-substitution procedure or a secondary-conditioning procedure, were maintained in a continuous-access environmental system in which operant lever press responses were required to receive 10% ethanol and food reinforcement. Water available from a drinking tube was electronically monitored to detect licks. Total daily consumption and patterns of food, water, and ethanol responding were analyzed under conditions in which the concentration of ethanol presented as a reinforcer was either 10% or 20%, and the response requirement for ethanol reinforcement was either a fixed ratio 4 schedule or a fixed ratio 1 schedule. Either increasing the ethanol concentration or decreasing the response requirement resulted in an increase in total daily ethanol intake. There was no significant difference between initiation procedures. These results are similar to observations in studies using a limited-access operant situation. This increased ethanol intake resulted from a complex alteration in the daily ethanol drinking pattern. The greatest ethanol intakes were observed when both the ethanol concentration was increased and response requirement was decreased. This was predominantly the result of increasing the number of ethanol drinking bouts per day when the response requirement was decreased, and by decreasing individual bout size by less than half when the ethanol concentration was doubled. These studies indicate that concentration of the ethanol presented as the reinforcer and the response cost required for reinforcement are involved in regulating ethanol consumption in the continuous-access condition. Type of initiation did not appear to interact with these variables.

Effects of morphine on acquisition and maintenance of ethanol and water intake patterns in rats.

Two experiments were conducted to assess the effects of chronic subcutaneous injections of morphine (1.0 mg/kg) or saline on the pattern and amount of sweetened ethanol and water intake in fluid restricted Long-Evans rats. Following daily injections, 2-h two-bottle choice tests were conducted with water and an ethanol solution (15% ethanol v/v in 5% sucrose w/v). During a 20-day acquisition phase (Experiment 1), ethanol intake patterns and amounts did not differ between saline (n = 6) and morphine (n = 6) groups. Both groups exhibited ethanol intake patterns that decreased exponentially throughout the session suggesting control by fluid restriction procedures. Morphine decreased water intake during initial periods of each session and increased intake during later periods. In Experiment 2, morphine and saline injections were reversed across three phases with the same rats. Morphine increased total ethanol consumption during the first few days of each 15-day phase, but the groups did not differ thereafter, and the initial increases produced no statistically significant group differences. Additionally, morphine augmented ethanol intake in early portions of sessions, while water intake was decreased and increased during early and later portions of each session, respectively. Analysis of the data from the last 5 days of each phase indicated that, when injected with morphine, the group which received saline during acquisition consumed significantly more ethanol solution than the group injected with morphine during acquisition. The effect on patterns of water and ethanol intake were observed, regardless of the drug injected during acquisition.(ABSTRACT TRUNCATED AT 250 WORDS)

The myelotoxicity of chloramphenicol: in vitro and in vivo studies: II: In vivo myelotoxicity in the B6C3F1 mouse.

1. Chloramphenicol continues to be widely used in many parts of the world despite its known haematotoxicity. Until now, elucidation of the mechanisms involved and any attempt at amelioration of the toxic effects have been hampered by the lack of an animal model. 2. In this study neither acute nor chronic administration of chloramphenicol as its succinate ester in the drinking water produced anaemia in mice as assessed by changes in peripheral blood parameters. 3. Chloramphenicol could not be detected in the bone marrow when the antibiotic was administered either in the drinking water or by gavage, although it was detected in the serum. 4. In marrow taken from mice after chloramphenicol succinate administration and cultured in vitro, depression of the differentiation of immature committed erythroid progenitors occurred 15 min after administration of the antibiotic by gavage. However, recovery was beginning to occur at 48 h after administration of chloramphenicol succinate at 50 and 200 mg/kg and this was then followed by an 'overshoot' response at the higher dose. A toxic effect was therefore achieved in the bone marrow but this was probably masked in the peripheral blood by enhanced proliferation. 5. Morphological evidence of apoptosis was seen in erythroid and myeloid precursors in mice treated with 200 mg/kg. 6. The data suggest that the effect of chloramphenicol was at the differentiation stage of the committed marrow progenitor cells rather than at the replication stage of the stem cells and therefore this response appears to mimic the reversible bone marrow depression seen in the treated patient.

Haemotoxicity of chloramphenicol succinate in the CD-1 mouse and Wistar Hanover rat.

1. Chloramphenicol has been widely used in the treatment of serious infections including typhoid fever and meningitis. However, the drug is haemotoxic in man inducing firstly, a reversible, dose-dependent anaemia which develops during treatment, secondly, an often fatal aplastic anaemia with pancytopenia and acellular marrow, and thirdly, leukaemia. 2. We investigated the haemotoxicity of chloramphenicol succinate (CAPS) in female CD-1 mice in repeat dose studies, to compare the response with the reversible anaemia reported in man. Studies in male Wistar Hanover rats were also carried out. 3. CAPS was gavaged daily to mice at dose levels from 800 - 2000 mg/kg for seven days. Values were significantly reduced for reticulocytes at 1700 and 2000 mg/kg, and for erythrocytes (RBC), haematocrit (HCT), and haemoglobin (Hb) at 2000 mg/kg. Platelet and white blood cell (WBC) counts were unaffected. 4. Mice were dosed with CAPS at 1400 mg/kg for 10 days and sampled at 1, 4 and 15 days after the last dose. At day 1 post dosing, RBC, HCT and Hb values were significantly reduced, but returned to normal (or above normal) by day 4 or 15. 5. CAPS from 2000 - 4000 mg/kg was gavaged to rats daily for 19 days. Hb values were significantly lower at 3600 and 4000 mg/kg; reticulocytes were not reduced. WBC and platelet counts, in general, were unaffected. 6. Levels of apoptosis in marrow mononuclear cells were increased in CAPS-treated mice, but not in CAPS-treated rats. Serum biochemistry parameters, in general, showed few changes of toxicological significance. 7. We conclude that the administration of CAPS to CD-1 mice induced haematological changes showing close parallels with the chloramphenicol-induced reversible anaemia seen in man.

Mother-infant interaction and breastfeeding outcome 6 weeks after birth.

OBJECTIVE: This study explored the relationship of early postpartum maternal-infant interactions to breastfeeding outcome at 6 weeks postpartum. DESIGN: Prospective, comparative descriptive study. SETTING: Women, Infants, and Children Supplemental Nutrition Program and Comprehensive Perinatal Services Programs in northern California. PARTICIPANTS: Forty-two Latina participants were recruited in the 3rd trimester of pregnancy. Eligibility criteria included age 18 years or older, primiparous at recruitment, antepartum desire to breastfeed 8 weeks or longer postpartum, planned hospital birth, full-term vaginal birth of a healthy newborn, and an uncomplicated, immediate postpartum course for mother and newborn, including being discharged together. MAIN OUTCOME MEASURES: The study examined breastfeeding dyads' early postpartum scores on Barnard's Nursing Child Assessment Feeding Scale (NCAFS) in relation to breastfeeding outcome 6 weeks postpartum. NCAFS tests were performed 28-90 hours postpartum in the participants' homes, and breastfeeding status was assessed by phone contact 6 weeks postpartum. RESULTS: Dyads continuing to breastfeed at 6 weeks postpartum had significantly higher early postpartum NCAFS scores than did dyads who had weaned from the breast by 6 weeks postpartum. CONCLUSIONS: Optimal maternal-infant interactions, as evidenced by higher scores on Barnard's NCAFS, were related to longer breastfeeding duration. Lower scores on the NCAFS, suggesting difficulties in maternal-infant interaction, were related to weaning earlier than planned.

The length of the second stage of labor in uncomplicated, nulliparous African American and Puerto Rican women.

The Friedman Curve of Normal Labor, based on Emanuel Friedman's studies of Caucasian women in 1954 and 1955, remains the "gold standard" for assessing progress in the second stage of labor. Clinical observation by the authors, however, suggests that the second stage of labor is shorter in African American and Puerto Rican women. This descriptive, comparative study examined the duration of the second stage of labor in nulliparous African American and Puerto Rican women with uncomplicated births. The labor and delivery records of 373 African American and 157 Puerto Rican nulliparous women were randomly selected and reviewed, and the mean durations of the second stage of labor for both groups were compared to Friedman's labor curve. The mean length of second stage of labor in the sample of African American women was 31.6 minutes with a standard deviation of +/- 22.5 minutes, significantly shorter than Friedman's duration (P < .01). The mean length of second stage of labor in the sample of Puerto Rican women was 44.32 minutes with a standard deviation of +/- 33.03 minutes. This was also shorter than Friedman's figure for the second stage of labor (P < .01). These findings provide a more appropriate curve for monitoring labor progress in women from different ethnic backgrounds.

The effect of epidural analgesia on the second stage of labor.

A retrospective review of 202 randomly selected records of parturient labors examined the relationship between cervical dilation at epidural analgesia administration and length of the second stage of labor. The epidural group received bupivacaine 0.11% or 0.125% with sufentanil 1 to 2 micrograms/mL using a Bard Patient Controlled Anesthesia II pump. Labor management and outcomes were compared with a nonepidural group who chose unmedicated childbirth, intravenous narcotics, or pudendal block. A significant inverse correlation was found between cervical dilation at epidural administration and second-stage length in labors that did not use oxytocin. However, linear regression explained only 13.5% of the variance, leaving 86.5% unexplained. In labors in the epidural group that used oxytocin, cervical dilation at epidural administration was not correlated with second-stage length. The epidural group experienced a significantly longer mean length of the second stage. Labors in the epidural group were 3.5 times more likely to have oxytocin induction or augmentation and 4.5 times more likely to experience instrument-assisted delivery. There were no significant differences in Apgar scores between the two infant groups.

Outcome following stabilization of type B1 periprosthetic femoral fractures.

We present results of internal stabilization of 16 type B1 periprosthetic femoral fractures following total or hemiarthroplasty of the hip. Seven patients had cemented stems, and the rest had cementless, extensively hydroxyapatite-coated stems. Fourteen were managed by a cable-grip plating system, 1 by Dynamic compression plate, and 1 had insertion of cables only. Minimum follow-up was 1 year. Four patients had a major complication: 2 had deep infection; 1 had nonunion requiring amputation; and 1 had persistent hip pain requiring removal of all metalwork, including the hip prosthesis. The average time to healing in the remaining patients was 16.3 weeks. Harris Hip Scores dropped from an average of 86.8 preoperatively to 73.4 on last follow-up. Periprosthetic fractures are a significant injury, with a high risk of complications.