A comparison of nutrient uptake efficiency and growth rate between different macrophyte growth forms

Aquatic macrophytes grow abundantly in many lowland streams and play a key role in ecosystem functioning, such as nutrient retention. In this study, we performed a microcosm experiment to quantify and compare the contribution of two freshwater macrophyte growth forms to nutrient cycling. We measured and compared inorganic nitrogen (NH₄-N and NO₃-N) and phosphorus (PO₄-P) uptake kinetic parameters (V_max and C_min) in 12 submerged and seven amphibious plant species. We tested whether relative growth rate (RGR) was related to high V_max and low C_min, and quantified changes in nutrient uptake kinetic in a subset of six out of 19 plants species during the growth season. Uptake rates of NH₄-N were higher in submerged compared to amphibious plants, whereas uptake rates of NO₃-N were significantly higher in amphibious species; PO₄-P uptake kinetics were not significantly different between the two growth forms. There were also significant seasonal differences in V_max NH₄-N rate among both submerged and amphibious species and in V_max NO₃-N among amphibious species. Highest uptake rates were observed in summer for both submerged and amphibious species. Overall, we found that nutrient uptake kinetics differed between the two growth forms within and between seasons. Consequently, the presence of both growth forms should extend the period of nutrient uptake across the year and enhance nutrient uptake within seasons. We conclude that higher functional diversity enhances annual nutrient uptake in streams and that stream restoration efforts should consider increasing the niche space available for both submerged and amphibious species.

Submerged freshwater plant communities do not show species complementarity effect in wetland mesocosms

It is a generally accepted theory that ecological functions are enhanced with increased diversity in plant communities due to species complementarity effects. We tested this theory in a mesocosm study using freshwater submerged plant beds to determine if increasing species number caused overyielding and species complementarity. We applied a maximum of four species in the plant beds corresponding to the typical species number in natural freshwater plant beds. We found no clear effects of species number (1-4) on biomass production and thus no conclusive overyielding and complementarity effect. This may be explained by low species differentiation among the four species in plant traits relevant for resource acquisition in freshwater, or that other species interactions, e.g. allelopathy, were inhibiting overyielding. The existing knowledge on species complementarity in aquatic plant communities is sparse and inconclusive and calls for more research.

Anomalously high geothermal flux near the South Pole

Melting at the base of the Antarctic Ice Sheet influences ice dynamics and our ability to recover ancient climatic records from deep ice cores. Basal melt rates are affected by geothermal flux, one of the least constrained properties of the Antarctic continent. Estimates of Antarctic geothermal flux are typically regional in nature, derived from geological, magnetic or seismic data, or from sparse point measurements at ice core sites. We analyse ice-penetrating radar data upstream of South Pole revealing a ~100 km long and 50 km wide area where internal ice sheet layers converge with the bed. Ice sheet modelling shows that this englacial layer configuration requires basal melting of up to 6 ± 1 mm a-1 and a geothermal flux of 120 ± 20 mW m-2, more than double the values expected for this cratonic sector of East Antarctica. We suggest high heat producing Precambrian basement rocks and hydrothermal circulation along a major fault system cause this anomaly. We conclude that local geothermal flux anomalies could be more widespread in East Antarctica. Assessing their influence on subglacial hydrology and ice sheet dynamics requires new detailed geophysical observations, especially in candidate areas for deep ice core drilling and at the onset of major ice streams.

Religious Scholars' Attitudes and Views on Ethical Issues Pertaining to Pre-Implantation Genetic Diagnosis (PGD) in Malaysia

Pre-Implantation Genetic Diagnosis (PGD) represents the first fusion of genomics and assisted reproduction and the first reproductive technology that allows prospective parents to screen and select the genetic characteristics of their potential offspring. However, for some, the idea that we can intervene in the mechanisms of human existence at such a fundamental level can be, at a minimum, worrying and, at most, repugnant. Religious doctrines particularly are likely to collide with the rapidly advancing capability for science to make such interventions. This paper focuses on opinions and arguments of selected religious scholars regarding ethical issues pertaining to PGD. In-depth interviews were conducted with religious scholars from three different religious organizations in the Klang Valley, Malaysia. Findings showed that Christian scholars are very sceptical of the long-term use of PGD because of its possible effect on the value of humanity and the parent-children relationship. This differs from Islamic scholars, who view PGD as God-given knowledge in medical science to further help humans understand medical genetics. For Buddhist scholars, PGD is considered to be new medical technology that can be used to save lives, avoid suffering, and bring happiness to those who need it. Our results suggest that it is important to include the opinions and views of religious scholars when it comes to new medical technologies such as PGD, as their opinions will have a significant impact on people from various faiths, particularly in a multi-religious country like Malaysia where society places high value on marital relationships and on the traditional concepts of family.

Allergenic components of a novel food, Micronesian nut Nangai (Canarium indicum), shows IgE cross-reactivity in pollen allergic patients

BACKGROUND

New foods may present a risk for food hypersensitive patients. Several examples exist of allergic reactions caused by cross-reactive plant-derived foods, and new foods should be scrutinised before introducing them to the market. We have evaluated the clinical and serological relevance of cross-reactivity between Nangai and pollen allergens.

METHODS

Cross-reactivity was examined with Maxisorp RAST (radioallergosorbent test), RAST inhibition and Western blot, using sera from patients allergic to grass, birch and mugwort pollen. None of the patients reported having seen or eaten Nangai previously. To determine the biological and clinical relevance of the cross-reactivity, histamine release (HR) test, skin prick test (SPT) and food challenge were used.

RESULTS

There was prevalence for reactivity against Nangai in the group of pollen allergic patients. This cross-reactivity seems to be related--at least in part--to carbohydrate epitopes. Three out of 12 patients tested with Nangai were positive upon open challenge, but using double blind placebo controlled food challenge (DBPCFC) this could not be confirmed in two patients. The biological effects of Nangai on allergic patients were confirmed using HR and SPT.

CONCLUSION

The Nangai specific IgE found among pollen allergic patients addresses the need for control of new or changed foods before introduction to the market.

On-pump versus off-pump coronary artery bypass: independent risk factors and off-pump graft patency

OBJECTIVE

Current knowledge on off-pump coronary artery bypass (OPCAB) generally stems from single surgeons' experience or from series where OPCABs constituted a minor fraction of coronary operations. The present center decided to venture as far into OPCAB as possible during 1999. The present series thus represents the average surgeon's experience.

METHODS

During 1999, 533 patients underwent coronary artery bypass grafting using cardiopulmonary bypass (CPB) in 368 and OPCAB in 165 including the circumflex artery (CX) area in 91. Coronary arteriography was performed before discharge in the first 103 OPCAB patients.

RESULTS

The CPB and OPCAB groups differed as regards left ventricular ejection fraction (53+/-13 versus 57+/-11, P < 0.0001) and frequency of triple-vessel or left main stem disease (84 versus 32%, P < 0.0001) but were comparable as regards diabetes (12%), prior myocardial infarct (57%), unstable angina (21%), and previous heart surgery (3%). Using multivariate analyses, 30-day mortality (1.3%), P-creatine kinase myocardial band (CKMB) > 80 microg/l (11.1%), re-sternotomy for bleeding (4.5%) or dehiscense (1.7%), transitory cerebral ischemia and stroke (1.7%), supraventricular tachycardia (27.4%), and hospital stay (mean 8 days) were unrelated to off- versus on-pump surgery as well as to OPCAB in triple-vessel disease. CX branches < or = 1mm, > or = 5 distal anastomoses, prior heart surgery, right coronary artery (RCA) branches < or = 1.5mm, 8-21 days old myocardial infarct, female gender, and preoperative acute arrhythmia (among others) were identified as independent risk factors for mortality or increased CKMB in all 533 patients. The latter five risk factors were reproduced in the OPCAB group isolated. The patency in the 103 OPCABs was 95.3, 91.8, and 85.3% in the left anterior descending artery (LAD), CX, and RCA, respectively. Patency was inversely related to diameter of the grafted vessel in the LAD and CX areas, unlike the RCA area.

CONCLUSIONS

The results after beating heart surgery were good also in patients with triple-vessel disease, but specific gains relative to on-pump surgery could not be shown. The independent risk factors in the OPCAB group may indicate relative contraindications for OPCAB grafting.

[Coronary artery bypass without use of the heart-lung-machine]

INTRODUCTION

Off pump coronary artery bypass via sternotomy (OPCAB) and via a small left anterior thoracotomy (MIDCAB) on the anterior coronary arteries of the heart was introduced at the present center in 1997. Starting this year we decided to increase OPCAB and MIDCAB to constitute at least 50% of CAB procedures including the posterior aspect of the heart.

METHODS

From January 1st through April 16th 1999 we performed 152 CAB procedures: 108 CABG, 6 MIDCAB, 13 OPCAB (on the anterior cornary arteries) and 25 OPCAB-Cx (including the circumflex artery). OP procedures were done using OCTOPUS-II to expose and stabilize the arteriotomies, and control angiography was performed before discharge.

RESULTS

Off pump CAB was performed in 2% of the first 50 CAB patients, 36% of the next 50 and 50% of the last 52. The CABG and OPCAB-Cx groups were comparable as regards degree of coronary artery disease and number of distal anastomoses, but differed as regards poor left ventricular function and unstable preoperative status. Early mortality was 1.9% in the CABG group and 0% in the OP groups. Control angiograms in the OP groups showed a patency from 92 to 100%.

CONCLUSIONS

In this short preliminary series, it was possible to increase the fraction of OP procedures to nearly 50% with good results.

Hearing loss after cardiopulmonary bypass surgery

Hearing loss (HL) is a rare complication following cardiac surgery with extracorporal circulation (CSWEC) or other non-otologic surgery under general anesthesia, as is HL caused by loss of cerebrospinal fluid during neurosurgery or spinal anesthesia. The incidence of HL after CSWEC is not known since preoperative hearing testing is not commonly done and a perioperative HL may occur unnoticed. We present four cases of profound sensorineural hearing loss following CSWEC for coronary artery bypass or cardiac valve surgery. The hearing loss was noticed immediately on waking from anesthesia in three of the patients, whereas the fourth patient noticed decreased hearing during the first postoperative week. In all patients audiological investigation suggested a cochlear etiology of the HL. The possible mechanisms for HL are discussed. HL after CSWEC is most likely caused by a microembolism generated by atheromatous material.

Cytodifferentiation and transformation of embryogenic callus lines derived from anther culture of wheat

Three types of callus tissues established from anther culture of eleven doubled haploid (DH) lines of wheat (Triticum aestivum L.) were evaluated for their ability in enhancing friable embryogenic (Type II) culture differentiation and genetic transformation. Differences between types of callus inocula were highly significant (P < 0.001), suggesting that the quality of the initial callus explant is of profound importance in encouraging the proliferation of Type II cultures. Other factors found to be crucial included weekly subculture of friable embryogenic callus tissues on a maintenance medium containing 30 microM dicamba and a predominance of amino-acid nitrogen supplement. Transfer and integration of the beta-glucuronidase gene was also affected by the type of inoculum when suitable embryogenic cell cultures were transformed using silicon carbide whiskers and high velocity microprojectiles. Expression of the hygromycin phosphotransferase selectable marker gene sequence was confirmed in all the stably transformed cell lines maintained on selection media containing lethal levels of hygromycin. Comparatively, there were differences in the frequency of regenerable, transgenic clonal segments between whisker-treated and microprojectile bombarded tissues mainly as a result of the fact that cultures vortexed with whiskers were more capable of post-treatment cell proliferation and embryo differentiation than those bombarded with cDNA-coated microprojectiles. Conditions for obtaining these results are outlined and discussed in relation to the suitability of the two transformation strategies for producing transgenic cell aggregates of wheat.

Intraluminal papaverine with pH 3 doubles blood flow in the internal mammary artery

Seventy-five patients undergoing coronary artery bypass grafting were randomized to receive injections of papaverine solution or isotonic saline or no injection into the left internal mammary artery (LIMA) used as graft. Blood flow in the LIMA was measured twice-after dissection of the pedicle and before anastomosis to the coronary artery. Blood flow increased significantly in all three groups, but after papaverine injection it was twice as high as in the control groups, increasing by 285% (from 40 +/- 12 to 154 +/- 32 ml/min, p = < 0.0001). The pH of the papaverine solution was only 3, and we advise that surgeons check and correct pH in the papaverine solutions they use, in order to avoid endothelial damage to the LIMA. Based on these results we can recommend papaverine injection into the arterial graft only if the initial flow is low.

[Traumatic rupture of a main bronchus. Clinical and peroperative presentation, physiopathological mechanisms, treatment and late sequelae]

On the basis of a case report, the clinical and peroperative features of bronchial rupture caused by blunt thoracic trauma, theories concerning the pathophysiological mechanisms, the treatment and outcome are reviewed. Two distinct clinical presentations may occur: (a) with free communication between the bronchus and the pleura (as in the present case) and (b) with little or no communication. The suspected diagnosis is confirmed by bronchoscopy. Peroperatively, bronchial rupture is seen at places of reduced resistance (the junction between the cartilaginous and the membranous trachea or bronchus and the annular ligaments) and typically within 2.5 cm from the carina. The pathophysiological basis includes three mechanisms: decrease in the anteroposterior diameter of the thorax, sudden increase in intrabronchial pressure with a closed glottis and rapid deceleration. These mechanisms may occur independently or together. The initial treatment aims at maintaining the airway, reversing shock and relieving pneumothorax. Surgical repair should follow as soon as the condition of the patient permits. The optimal surgical technique is identical with that employed for vascular anastomoses. Surgical repair of bronchial rupture should only be omitted if extensive parenchymal pulmonary damage and/or suppuration are present. Even after years of delay, reconstruction will lead to partial recovery of pulmonary function.

Moclobemide and clomipramine in reactive depression. A placebo-controlled randomized clinical trial

The purpose of this study was to compare moclobemide and clomipramine in reactive depression according to the Newcastle II classification. Sixty patients were allocated to either 300 mg moclobemide, 150 mg clomipramine or placebo, all divided in 3 daily doses. Improvements occurred over time, but differences between treatments and compared with placebo were never statistically significant. Dizziness, tremor and anticholinergic symptoms were significantly more frequent with clomipramine than with moclobemide and placebo.

Prospective controlled vagotomy trial for duodenal ulcer. Results after 11-15 years

A prospective, randomized, controlled trial was conducted to compare truncal vagotomy and drainage (TV), selective vagotomy and drainage (SV) and parietal cell vagotomy (PCV) as elective treatment for duodenal ulcer. Between 11 and 15 years after operation, 248 patients were available for study of the recurrent ulceration rate by a life table method, and 197 patients could be studied with regard to postvagotomy symptoms. The recurrent ulcer rates were 28.5% for TV, 37.4% for SV, and 39.3% for PCV. These differences were not statistically significant. The incidence of severe postvagotomy symptoms was as follows: dyspepsia, 18.4% for TV, 20.5% for SV, 8.6% for PCV; dumping, 5.9% for TV, 19.6% for SV, 2.2% for PCV; diarrhea, 9.8% for TV, 11.8% for SV, 4.4% for PCV. The incidence of severe dumping was significantly less frequent among the PCV patients than the SV group. The differences did not reach statistical significance in any of the other groups. There was no significant difference in the Visick gradings among the three groups either before or after treatment of the failures. About two thirds of the patients in each group were finally satisfied with their operation, often after second operations or prolonged medical treatment. It is concluded that none of the three forms of vagotomy can be recommended as the standard operative treatment of duodenal ulceration.

Prospective 14- to 18-year follow-up study after parietal cell vagotomy

One hundred and thirty-five patients underwent elective parietal cell vagotomy for duodenal, pyloric or prepyloric ulcers. The patients were followed prospectively at intervals of 1-3 years in order to detect postvagotomy symptoms and recurrent ulcers; 14-18 years after surgery 106 patients were studied with regard to recurrent ulceration and 84 concerning postvagotomy symptoms. Thirty-two patients (30 per cent) had developed proven recurrent ulcers and a further 9 per cent were suspected of having recurrences. Two patients were reoperated for gastric outlet obstruction and one for bile reflux gastritis. Four patients had severe dyspeptic symptoms and four severe dyspepsia plus dumping. No patient had severe diarrhoea. Forty-three patients were regarded as failures after parietal cell vagotomy. After treatment of these failures 88 per cent of the patients available for subsequent follow-up had satisfactory results. The alternatives to parietal cell vagotomy are discussed. It is concluded that although parietal cell vagotomy has a high long-term recurrence rate, this disadvantage is outweighed by the low incidence severe postvagotomy symptoms.

Results of surgical treatment for lung cancer

A review is presented of 233 patients who were surgically treated for bronchial carcinoma during a five-year period. The survival time was determined in relation to operative procedure and to cell type and anatomic extent of the tumours. Staging according to the TNM classification gave five-year survival rates of 51.6% in Stage I, 12.0% in Stage II and 8.4% in Stages III-IV. Among the Stage I cases, tumours classified as T1N0M0 were associated with longer survival than were T1N1M0 or T2N0M0 tumours. It is concluded that the stage of the disease as defined by TNM classification should be regarded as the most important prognostic factor.