Contributions of climate, leaf area index and leaf physiology to variation in gross primary production of six coniferous forests across Europe: a model-based analysis

Gross primary production (GPP) is the primary source of all carbon fluxes in the ecosystem. Understanding variation in this flux is vital to understanding variation in the carbon sink of forest ecosystems, and this would serve as input to forest production models. Using GPP derived from eddy-covariance (EC) measurements, it is now possible to determine the most important factor to scale GPP across sites. We use long-term EC measurements for six coniferous forest stands in Europe, for a total of 25 site-years, located on a gradient between southern France and northern Finland. Eddy-derived GPP varied threefold across the six sites, peak ecosystem leaf area index (LAI) (all-sided) varied from 4 to 22 m(2) m(-2) and mean annual temperature varied from -1 to 13 degrees C. A process-based model operating at a half-hourly time-step was parameterized with available information for each site, and explained 71-96% in variation between daily totals of GPP within site-years and 62% of annual total GPP across site-years. Using the parameterized model, we performed two simulation experiments: weather datasets were interchanged between sites, so that the model was used to predict GPP at some site using data from either a different year or a different site. The resulting bias in GPP prediction was related to several aggregated weather variables and was found to be closely related to the change in the effective temperature sum or mean annual temperature. High R(2)s resulted even when using weather datasets from unrelated sites, providing a cautionary note on the interpretation of R(2) in model comparisons. A second experiment interchanged stand-structure information between sites, and the resulting bias was strongly related to the difference in LAI, or the difference in integrated absorbed light. Across the six sites, variation in mean annual temperature had more effect on simulated GPP than the variation in LAI, but both were important determinants of GPP. A sensitivity analysis of leaf physiology parameters showed that the quantum yield was the most influential parameter on annual GPP, followed by a parameter controlling the seasonality of photosynthesis and photosynthetic capacity. Overall, the results are promising for the development of a parsimonious model of GPP.

The Drosophila VEGF receptor homolog is expressed in hemocytes

Several signalling pathways have been defined by studies of genes originally characterised in Drosophila. However, some mammalian signalling systems have so far escaped discovery in the fly. Here, we describe the identification and characterisation of fly homologs for the mammalian vascular endothelial growth factor/platelet derived growth factor (VEGF/PDGF) and the VEGF receptor. The Drosophila factor (DmVEGF-1) gene has two splice variants and is expressed during all stages, the signal distribution during embryogenesis being ubiquitous. The receptor (DmVEGFR) gene has several splice variants; the variations affecting only the extracellular domain. The most prominent form is expressed in cells of the embryonic haematopoietic cell lineage, starting in the mesodermal area of the head around stage 10 of embryogenesis. Expression persists in hemocytes as embryonic development proceeds and the cells migrate posteriorly. In a fly strain carrying a deletion uncovering the DmVEGFR gene, hemocytes are still present, but their migration is hampered and the hemocytes remain mainly in the anterior end close to their origin. These data suggest that the VEGF/PDGF signalling system may regulate the migration of the Drosophila embryonic haemocyte precursor cells.

Post-ERCP pancreatitis: reduction by routine antibiotics

Cholangitis and pancreatitis are severe complications of endoscopic retrograde cholangiopancreatography (ERCP). Antibiotics have been considered important in preventing cholangitis, especially in those with jaundice. Some have suggested that bacteria may play a role in the induction of post-ERCP pancreatitis. It is not clear, however, whether the incidence of post-ERCP pancreatitis could be reduced by antibiotic prophylaxis, as is the case with septic complications. In this prospective study, a total of 321 consecutive patients were randomized to the following two groups: (1) a prophylaxis group (n = 161) that was given 2 g of cephtazidime intravenously 30 minutes before ERCP, and (2) a control group (n = 160) that received no antibiotics. All patients admitted to the hospital for ERCP who had not taken any antibiotics during the preceding week were included. Patients who were allergic to cephalosporins, patients with immune deficiency or any other condition requiring antibiotic prophylaxis, patients with clinical jaundice, and pregnant patients were excluded. In the final analysis six patients were excluded because of a diagnosis of bile duct obstruction but with unsuccessful biliary drainage that required immediate antibiotic treatment. The diagnosis of cholangitis was based on a rising fever, an increase in the C-reactive protein (CRP) level, and increases in leukocyte count and liver function values, which were associated with bacteremia in some. The diagnosis of acute pancreatitis was based on clinical findings, and increases in the serum amylase level (>900 IU/L), CRP level, and leukocyte count with no increase in liver chemical values. The control group had significantly more patients with post-ERCP pancreatitis (15 of 160 in the prophylaxis group vs. 4 of 155 in the control group; P = 0.009) and cholangitis (7 of 160 vs. 0 of 155; P = 0.009) compared to the prophylaxis group. Nine patients in the prophylaxis group (6%) and 15 patients in the control group (9%) had remarkably increased serum amylase levels (>900 IU/L) after ERCP, but clinical signs of acute pancreatitis with leukocytosis, CRP reaction, and pain developed in four of nine patients in the prophylaxis group compared to 15 of 15 patients with hyperamylasemia in the control group (P = 0.003). In a multivariate analysis, the lack of antibiotic prophylaxis (odds ratio 6.63, P = 0.03) and sphincterotomy (odds ratio 5.60, P = 0.05) were independent risk factors for the development of post-ERCP pancreatitis. We conclude that antibiotic prophylaxis effectively decreases the risk of pancreatitis, in addition to cholangitis after ERCP, and can thus be routinely recommended prior to ERCP. These results suggest that bacteria could play a role in the pathogenesis of post-ERCP pancreatitis

Sinusitis in the common cold

BACKGROUND

Acute community-acquired sinusitis is considered a bacterial complication of the common cold. Radiologic abnormalities in sinuses occur, however, in most patients with upper respiratory virus infections.

OBJECTIVE

Assessment of the occurrence, clinical profile, laboratory findings, and outcome of radiologically confirmed sinusitis was carried out as part of a common cold study in young adults.

METHODS

Clinical examinations and radiography of the paranasal sinuses were carried out on days 1, 7, and 21 in 197 patients with the common cold. The symptoms were recorded on diary cards on days 1 to 20. Ten viruses and 5 bacteria were studied as etiologic agents of common cold as reported earlier. Serum C reactive protein concentrations, erythrocyte sedimentation rates, and total white blood cell counts with differentials were determined in 40 randomized subjects on day 7. The effect of 6 days of intranasal fluticasone propionate treatment of the common cold in the prevention of sinusitis was analyzed.

RESULTS

On day 7, 39% of patients with the common cold in the placebo group (n = 98) had sinusitis, which we would prefer to call viral sinusitis. The symptoms of patients with sinusitis and those without it were not clinically distinguishable. Viral infection was detected in 81.6% of patients with sinusitis. No significantly increased levels of antibodies to bacteria were detected. Serum C reactive protein concentrations, erythrocyte sedimentation rates, and white blood cell counts were low in patients with sinusitis. All patients made a clinical recovery within 21 days without antibiotic treatment. Fluticasone propionate treatment tended to prevent paranasal sinusitis, especially in rhinovirus-positive subjects.

CONCLUSION

Viral sinusitis frequently occurs in the early days of the common cold, but it is a self-limited illness. The sinuses should not be imaged in patients with the common cold if the signs and symptoms of illness gradually become less severe and no specific signs suggestive of bacterial sinusitis occur.

The common cold: effects of intranasal fluticasone propionate treatment

OBJECTIVE

A double-blind, randomized, placebo-controlled trial was conducted to study the effect of the intranasal corticosteroid, fluticasone propionate (FP), in the naturally occurring common cold.

METHODS

One hundred ninety-nine young adults received high-dose FP (200 microg four times daily) or placebo beginning 24 to 48 hours after onset of the common cold for 6 days. All symptoms were recorded on diary cards on days 1 to 20, and clinical examinations were carried out on days 1, 7, and 21. Nasopharyngeal aspirates were collected on days 1 and 7 for detection of rhinoviruses (found in 105 subjects) and Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis (found in 52 subjects) in the nasopharynx.

RESULTS

In general, FP treatment had no clinically recognizable effects on the symptoms of the common cold, although it significantly reduced nasal congestion and cough on some study days. After treatment, rhinoviruses were cultured more often in the FP treatment group (37% vs 14%, p < 0.001), but this had no effect on the symptoms of common cold. FP treatment produced no changes in the colonization of pathogenic bacteria in the nasopharynx. Some symptoms of common cold were significantly more severe during days 1 to 10 (p < 0.05) in subjects found to have positive cultures for S. pneumoniae, H. influenzae, or M. catarrhalis in the nasopharynx on day 1 (n = 33).

CONCLUSION

FP treatment does not have any marked effects on the symptoms of the common cold. FP treatment induced prolonged shedding of viable rhinoviruses. Some symptoms of the common cold were significantly more severe in subjects with pathogenic bacteria in the nasopharynx.

The effect of nimesulide and naproxen on the uterine and ovarian arterial blood flow velocity. A Doppler study

BACKGROUND

To measure the effect of oral naproxen and nimesulide treatments on the uterine and ovarian arterial blood flow velocity in both eumenorrheic and dysmenorrheic women.

METHODS

The double-blind, placebo-controlled, study comprised six eumenorrheic women receiving either placebo or nimesulide (100 mg, single oral dose) during two consecutive cycles. Six women with moderate to severe dysmenorrhea were treated with placebo, nimesulide or naproxen (500 mg, single oral dose) during three consecutive cycles. Uterine impedance (pulsatile index, PI) was measured during the cycle day 1 at four different levels of the uterus and in the ovarian branch of the uterine artery at 0, 30, 60, and 120-140 min, with a color Doppler ultrasonograph for orientation and with pulsatile Doppler for recording waveforms.

RESULTS

In the eumenorrheic women no significant changes were found with any treatment. In dysmenorrheic patients, nimesulide relieved symptoms and caused a decrease in uterine artery PI earlier than naproxen. Both treatments reduced the elevated uterine impedance in dysmenorrhea close to the normal level. When analyzing the PIs of the uterine artery at 4 different levels, the most prominent changes were observed in the fundus. The ovarian branch remained unaffected.

CONCLUSIONS

Color Doppler ultrasonography and pulsatile Doppler are good methods for investigating disease- or drug-induced changes in uterine and ovarian blood flow velocities. Nimesulide induced a slightly faster and more complete decrease of the elevated uterine vascular resistance in dysmenorrhea, towards normal eumenorrheic levels, than naproxen. The fundal part of the uterus appears to be an important site of the pathogenesis in primary dysmenorrhea.

Myometrial estrogen and progesterone receptor binding in pregnancy: inhibition by the detergent action of phospholipids

We characterized the phospholipid inhibition of estradiol and progesterone binding to guinea-pig and human myometrial receptors. Of twelve compounds studied, phosphatidylinositol (PI), lysophosphatidic acid and lysophosphatidylcholine (lyso-PC) were the most active inhibitors (50% inhibition at 10(-5) M). Lyso-PC with fatty acid chain length C14:0 inhibited ligand binding both to estrogen receptor (ER) and progesterone receptor (PR), C16:0 only to PR and C18:0 neither to ER nor to PR. The lyso-derivates were more inhibitory than the parent compounds. The ionic detergent (sodium taurocholate) inhibited both ER and PR binding, but the non-ionic detergent (Triton X-100) only PR. Triton X-100 enhanced the PI-induced inhibition of ER binding by a factor of 10. PR was more sensitive to inhibition than ER in all cases. The type of inhibition was non-competitive. At term pregnancy, ligand binding to myometrial ER or PR was low or absent in humans, but moderate in the guinea-pig. Phospholipid extracts of human decidua and fetal membranes contained PI and phosphatidylserine rather than lyso-PC. The extract was a potent inhibitor of ligand binding to PR (50% inhibition at 10(-6) M phospholipid phosphorus), but not to ER. The physicochemical environment, modulated by phospholipids acting as detergents, may regulate sex steroid function also in vivo. This might have special significance for pregnancy maintenance.

Nimesulide in dysmenorrhoea

Nimesulide does not affect active intrauterine pressure, as measured using microsensors, or the direction and velocity of the propagation of uterine activity, but nevertheless alleviates pain significantly by 30 minutes after oral administration. In dysmenorrhoeic patients, resting pressure is high only in the fundus. Nimesulide reduces the pressure during the maximal but not during the submaximal pain period, with concomitant alleviation of pain. The drug changes the painful state of uterine contracture to painless cyclic contractions. With a single oral dose of 100mg, nimesulide is evenly distributed in female genital tissues (uterine fundus and cervix, oviduct and ovaries), reaching peak concentrations and peak plasma: tissue ratio (0.5) 3 hours after administration. Tissue concentrations range from 0.3 to 1.8 micrograms/g. Two 100mg oral doses of nimesulide administered to dysmenorrhoeic women in a double-blind placebo-controlled cross-over study reduced prostaglandin F2 alpha levels in menstrual blood from 382 to 94 micrograms/L. Double-blind placebo-controlled studies also confirmed that nimesulide relieves pain in dysmenorrhoeic patients.

Analysis of uterine contractility after administration of the non-steroidal anti-inflammatory drug nimesulide

To study the effects of non-steroidal anti-inflammatory drugs (NSAIDs) on uterine contractility in different parts of the uterus and on the direction and velocity of propagation of the activity, intra-uterine pressure (IUP) was measured simultaneously in 10 dysmenorrheic and 5 eumenorrheic patients with two microtransducer catheters at two locations (30 mm apart) before and after taking nimesulide, a newly developed NSAID. The uterus developed higher pressure cycles in the fundus than in the isthmus, in both eumenorrheic and dysmenorrheic conditions. Nimesulide did not affect either the active pressure (AP) or the direction and velocity of propagation of the activity, though it alleviated pain significantly. In dysmenorrheic patients, resting pressure (RP) is at a high level only in the fundus. The velocity of propagation ranged from 12 to 19 mm/s. The mathematical probability of procervical activity (1.0 if all procervical; 0.0 if all profundal), and thus the transport, was 0.59 in eumenorrheic and 0.68 in dysmenorrheic patients, the average for the whole series being 0.65. The luminal content (menstrual blood) moves in the cervical direction much more slowly than would be expected on the basis of simple calculations of velocity (velocity vector) of propagation.

"Menstrual induction" with Sulproston

The PGE2-analogue Sulproston (16-phenoxy-omega-17,18,19,20-tetranor-PGE2-mythylsulfonylamide) was administered to 200 medically and gynecologically normal women who were 17 +/- 0.4 days beyond their expected menstrual period and who had a positive pregnancy test. The intramuscular impact dose (500 micrograms repeated after 4 hours) caused an immediate tonic uterine contraction which compromised the estradiol 17 beta, progesterone and chorionic gonadotropin production within the fetoplacental unit, and thereby allowed the evolution of cyclic uterine activity, cervical dilatation and tissue expulsion. Pregnancy termination was complete in 92% of women, 5.5% required surgical curettage and 2.5% were given a second Sulproston treatment 2-3 weeks after the first to remove retained tissue from the uterus. The medical induction of menstruation was preferred by 83% of the women who had previously experienced surgical termination of pregnancy. Normal menstruation resumed in all women after 36 +/- 0.9 days. The majority of 42 women questioned found Sulproston a satisfactory, safe, simple and effective drug regimen for "menstrual induction".

The effect of antidiuretic hormone, indomethacin and naproxen on prostaglandin synthesis of experimentally infected and healthy kidneys

The authors studied the effect of indomethacin and naproxen on the changes of renal prostaglandin E and F2 alpha concentration in experimental kidney infection, as well as the action of arginine-vasopressin in healthy rats. Naproxen proved to be an effective inhibitor of prostaglandin synthesis, as did indomethacin. In control animals an increased prostaglandin E and F2 alpha synthesis was observed caused by arginine vasopressin. It is supposed that ADH--depending on its concentration--has a metabolic modulator role in prostaglandin synthesis, which raises the possibility of a self-regulatory mechanism of water reabsorption.

Pituitary-ovarian hormones after low-dose endometrial afterloading irradiation

Low-dose endometrial after loading irradiation was used in 19 mentally retarded women for the induction of therapeutic amenorrhea. They were divided into two subgroups on the basis of age: 13 young patients (mean age 17 years, range 13-26 years) and six patients of middle age (mean age 42 years, range 34-44 years). In the young patients, during the 10-month follow-up period, the plasma E2 levels did not decrease. However, the FSH concentration increased. Late on, 2-9 years after treatment, the E2 levels were significantly higher than those of healthy postmenopausal women and did not differ from the values of healthy women in the sixth to seventh days of the menstrual cycle. At that time the FSH and LH levels were similar to reference values in reproductive age. The E2/E1 ratio was significantly higher than that of healthy women in the sixth to seventh days of the cycle and that of postmenopausal women. Most of the menstrual cycles were anovulatory but some ovulatory also occurred. The testosterone concentrations did not differ from reference values. The ovaries of the middle age patients were more sensitive to irradiation than those of the younger patients.

Intestinal metabolism of estrogens

Estrogen metabolism in the human intestine was studied in two ways. Firstly, by measuring the excretion of 12 estrogens in pooled human late pregnancy feces before and during the administration of ampicillin (2 g/day). Secondly, by administering 5.4 and 20 mg of 16alpha-hydroxyestrone orally to two postmenopausal women and analyzing the estrogens in simultaneously drawn portal and peripheral venous blood samples at time intervals from 0 to 150 min after steroid administration. The majority of the estrogens in normal pregnancy feces were unconjugated. The amounts of estradiol, estreon and 16-epiestriol excreted, relative to the principal estrogen estriol, were greater than in pregnancy bile or urine and 16alpha-hydroxyestrone, an important biliary estrogen, was only present in trace amounts. Considerable quantities of 15alpha-hydroxyestradiol-17beta were also found. Ampicillin administration, which decreases intestinal bacterial steroid metabolism, caused a huge increase in the fecal excretion of conjugated estrogens. In particular it caused very striking increases in the excretion of both unconjugated and conjugated, estriol, 15alpha-hydroxyestrone, 15alpha-hydroxyestradiol and 2-methoxyestrone. These findings emphasize the active role played by the intestinal microflora in estrogen metabolism under normal conditions. Administration of 16alpha-hydroxyestrone resulted in increases in portal venous unconjugated and conjugated 16alpha-hydroxyestrone, 16-oxoestradiol-17beta, 15alpha-hydroxyestrone, 16-epiestriol and conjugated estriol levels. The most significant finding in both subjects was the large increase in portal venous unconjugated 15alpha-hydroxyestrone. This would suggest that the human intestine (or intestinal contents) has the ability to carry out the transformation, 16alpha-hydroxyestrone leads to 15alpha-hydroxyestrone. Increases in the same estrogens were found in peripheral plasma, with the increase in conjugated estriol occurring in peripheral blood before it was seen in portal blood. The largest elevations in peripheral plasma values were seen in unconjugated estriol and conjugated 16alpha-hydroxyestrone in the subject who received the 20 mg dose and in unconjugated 16alpha-hydroxyestrone and 16-oxoestradiol-17beta in the subject who had the 5.4 mg dose. The intestinal and enterohepatic metabolism of estrogens is discussed in relation to these findings.

Termination of pregnancy with double prostaglandin impact

With the "double PG impact" (DPGI) technique in 100 sedated first- and second-trimester volunteers, pregnancy was terminated successfully in 99 with a total extraovular PGF2alpha dose of 19.0 +/- 1.5 mg. in 16.9 +/- 0.9 hours. Two thirds of the patients received only the initial dose of 11.6 +/- 0.5 mg. of PG and aborted in 12.9 +/- 0.7 hours without requiring supplemental treatment. Only mild and transient side effects and 14 indicated curettages were recorded. Excepting one gravida (who failed to abort), plasma progesterone in 99 patients decreased at 3 hours after DPGI from 32.5 +/- 1.7 to 22.7 +/- 1.2 ng. per milliliter (P less than 0.001). The rate of progesterone withdrawal and IAT showed a close relationship and the first-trimester patients aborted at a lower progesterone level than the second-trimester patients (P less than 0.001).

Effect of ampicillin administration on the excretion of twelve oestrogens in pregnancy urine

The excretion of twelve oestrogens in urine, pooled daily from a group of pregnant women, was determined before, during and after ampicillin administration (2 g/day, for 3 days). On the second day of ampicillin administration total oestrogen excretion fell to 67% of the mean control value, oestriol excretion to 69% and that of the other eleven individual oestrogens to an average of 62% of the mean control values. In general, on the third day of treatment and on the two post-treatment days this decrease tended to be corrected. The patterns of change in the urinary levels of the individual metabolites provided no clear lead to the basic mechanism of ampicillin impairment of oestrogen excretion. However, as the drug affected all their excretion in more or less the same way as it did that of oestriol, it is possible that ampicillin interferes primarily with their enterohepatic circulation in the mother as has been established with reasonable certainty in the case of oestriol.