Is elongation-induced leaf emergence beneficial for submerged Rumex species?

BACKGROUND AND AIMS: Plant species from various taxa 'escape' from low oxygen conditions associated with submergence by a suite of traits collectively called the low oxygen escape syndrome (LOES). The expression of these traits is associated with costs and benefits. Thus far, remarkably few studies have dealt with the expected benefits of the LOES. METHODS: Young plants were fully submerged at initial depths of 450 mm (deep) or 150-240 mm (shallow). Rumex palustris leaf tips emerged from the shallow flooding within a few days, whereas a slight lowering of shallow flooding was required to expose R. acetosa leaf tips to the atmosphere. Shoot biomass and petiole porosity were measured for all species, and treatments and data from the deep and shallow submergence treatments were compared with non-flooded controls. KEY RESULTS: R. palustris is characterized by submergence-induced enhanced petiole elongation. R. acetosa lacked this growth response. Upon leaf tip emergence, R. palustris increased its biomass, whereas R. acetosa did not. Furthermore, petiole porosity in R. palustris was twice as high as in R. acetosa. CONCLUSIONS: Leaf emergence restores gas exchange between roots and the atmosphere in R. palustris. This occurs to a much lesser extent in R. acetosa and is attributable to its lower petiole porosity and therefore limited internal gas transport. Leaf emergence resulting from fast petiole elongation appears to benefit biomass accumulation if these plants contain sufficient aerenchyma in petioles and roots to facilitate internal gas exchange.

Influence of an increased intracranial pressure on cerebral and systemic haemodynamics during endoscopic neurosurgery: an animal model.

BACKGROUND: During endoscopic neurosurgery, direct mechanical stimulation of the brain by the endoscope and increased intracranial pressure (ICP) caused by the continuous rinsing can induce potentially lethal haemodynamic reflexes, brain ischaemia, and excessive fluid resorption. METHODS: In a newly presented rat model of endoscopic neurosurgery, stereotactic access to the cerebrospinal fluid was secured and the ICP was increased by controlled infusion until complete suppression of the cerebral perfusion pressure (CPP). The haematocrit (Hct) level was determined before and after the procedure. During the whole procedure, invasive arterial pressure, ICP, and heart rate were continuously recorded and evaluated in a subsequent offline analysis. After the procedure, the animals were allowed to recover and 7 days later they were killed for histological examination. RESULTS: Suppression of the CPP resulted in a severe hypertension combined with tachycardia or mild bradycardia. The Hct decreased from 41 to 35 over the minutes of CPP suppression. After cessation of the infusion, the ICP decreased to 37% of the plateau pressure within 2.5 s. In the first few minutes after restoration of normal ICP, five animals died because of pulmonary oedema. CONCLUSIONS: Upon complete suppression of the CPP, an obvious hypertension developed, often together with tachycardia, but no severe bradycardia. At high ICP levels, we observed an important translocation of irrigation fluid to the vascular space. Fatality was not caused by ischaemia or arrhythmia but due to pulmonary oedema.

The Leiden Early Arthritis Clinic.

In 1993 a special Early Arthritis Clinic (EAC) was established at the Department of Rheumatology of the Leiden University Medical Center in order to detect and treat inflammatory disorders early in the disease state, especially early rheumatoid arthritis. Patients with confirmed arthritis of recent onset (less than 2 years) were included by rheumatologists and trained research nurses. Parameters of first and follow-up visits (3, 6 and 9 months and yearly) that were entered in the EAC-database include the medical history, physical-diagnostic examination, laboratory tests, questionnaires, radiographic joint scores and diagnosis. This database enables us to conduct research on arthritis, with an emphasis on rheumatoid arthritis, in many ways. Physicians and basic scientists have studied cellular immunology and genetic, environmental and clinical risk factors in order to determine the pathophysiologic mechanisms of inflammatory arthritis. The present article is a review on reports published from the EAC. Over the past ten years, these reports have been highly relevant for both daily clinical practice and research. Present and planned future studies, as described in this article, reconfirm the importance of an EAC framework to ensure that research continues on this disease in the Leiden EAC area.

Anti-aggressive effect of a new phenylpiperazine compound (DU27716) on hypothalamically induced behavioural activities.

Using the same hypothalamic electrodes, the following behaviour was evoked in male rats by electrical stimulation at roughly equal current intensities: attacks on a partner, teeth-chattering, switch-off behaviour and locomotion. Current thresholds were determined for each behaviour following the intraperitoneal administration of saline or DU27716, a new phenylpiperazine compound with interesting inhibitory effects on territorial and intermale aggression. DU27716 raised current thresholds for attack and teeth-chattering beginning at the lowest dose (4 mg/kg), whereas there was no effect on switch-off behaviour, and only a slight but significant effect on locomotion thresholds at the highest dose (8 mg/kg). The results provide support for the hypothesis that DU27716 possesses behaviourally selective, anti-aggressive properties, and illustrate the usefulness of hypothalamically induced behaviours as a pharmacological model.

In vivo determination of radiographic projection errors produced by a novel filmholder and an x-ray beam manipulator.

Subtraction radiography requires radiographs made with identical projection geometry. The purpose of the present investigation was to develop and evaluate a new in vivo method to measure angular radiographic projection error. This included the development of a system for accurate control of the x-ray beam angulation relative to the intraoral film and the evaluation of the in vivo projection errors (equivalent to the "angular difference" between repeated exposures) produced by the new system. A filmholder, an x-ray beam manipulator, and an aiming device were newly constructed. Reference wires were attached for measuring the projection error on the filmholder and on the 22 bicuspids at the sites of investigation in 16 patients. Two exposures using standardized projection conditions were made of each site. The relative position of the reference wires on the duplicate radiographs was used to calculate the angular difference in the direction of the x-ray beam which occurred between the 2 exposures. Triplicate measurements allowed the determination of measurement error. The angular projection errors were measured in a horizontal and vertical direction. The reference wires allowed determination of the angular projection errors relative to the filmholder, relative to the dentition and the angular error due to the repositioning of the filmholder in the patient's mouth. The average projection errors deviated only slightly from zero. The largest deviation registered was -0.11 degrees. This applies to the horizontal and vertical direction and all relationships. The standard deviations varied between 0.403 degrees and 0.697 degrees. This applies to the standard deviation for all relationships in the horizontal, the vertical, and the oblique directions. The measuring error found from the triplicate measurements had a standard deviation of 0.08 degrees to 0.19 degrees depending on the distance between the reference wires. This new system for controlling in vivo projection errors seems to provide highly standardized radiographs in vivo. The new measuring system proved to be accurate enough to measure the in vivo projection errors between repeated radiographs produced with the new filmholder and x-ray beam manipulator. The in vivo errors produced by the new system are markedly smaller than all in vivo and in vitro errors previously reported in the literature.

Time-related changes of in vivo projection errors in standardized radiographs.

Subtraction radiography requires radiographs made with identical projection geometry. Recently a new radiographic aiming device and an x-ray beam manipulator made it possible to repeat radiographic exposures in vivo with small angular errors and to measure the angular errors occurring. The purpose of the present investigation was to study in vivo the measuring error and the angular errors produced by this new method at different time points (0, 6, and 12 months) and to assess the effect of different time intervals between exposures (0, 6, and 12 months). Ten sites were investigated. At each time point 2 exposures were made, resulting in 6 radiographs per site. For each pair of radiographs the measuring errors occurring during analysis and the projection errors were determined for each time point and for each time interval. Friedman's test and t-test were used to evaluate the errors. A difference in the measuring error of the system and in the angular errors at the time points 0, 6, and 12 months could not be detected. A time interval between exposures also did not have an effect on the measuring error. Time did not affect the vertical and horizontal angular errors measured between the radiographs producing the smallest oblique error. A combination of radiographs producing the largest oblique angular error showed an increase of the horizontal and vertical angular errors when the time interval increases. These effects, however, were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunohistochemical analysis of E-cadherin expression in human colorectal tumours.

The homotypic homophilic cell-cell adhesion molecule E-cadherin is crucial in the organization and maintenance of most epithelia. The expression of E-cadherin was studied immunohistochemically in various human colorectal tumours. Therefore we stained 1 tubular adenoma with low grade dysplasia, 18 adenocarcinomas with different histologic degrees of differentiation and invasion, and 1 metastasis using a modified peroxidase-anti-peroxidase technique. In the adenoma as well as in all well differentiated adenocarcinomas we found E-cadherin immunopositivity at the cell membrane of almost all cancer cells. The immunopositivity of E-cadherin was clearly weaker and sometimes even absent in isolated neoplastic cells and glands of less differentiated adenocarcinomas. The moderately differentiated adenocarcinomas showed an intermediate staining pattern. These findings are in line with experimental evidence that downregulation of E-cadherin favours invasion, eventually leading to metastasis.

Positron emission tomography study of the human hypothalamus during normal ageing and in ischemic and degenerative disorders.

Regional blood flow and oxygen metabolism were determined by positron emission tomography, using the steady state technique with 15O, in the hypothalamus and in the whole brain of fifty two normal persons and patients suffering from cerebral ischemia and degenerative dementia. During normal ageing regional blood flow and oxygen consumption appeared to increase slightly in the hypothalamus and to decrease in the whole brain in 24 persons. In the young age group the hypothalamus was more protected against ischemia than in the elderly group. In the aged group with cerebral ischemia and degenerative dementia regional blood flow and oxygen consumption were decreased in the hypothalamus to the same extent as in the whole brain.

A large intracranial xanthoma in familial hypercholesterolemia.

Intracranial xanthomata occurring in patients with familial hypercholesterolemia are very rare. We present a young woman with a large intracranial xanthoma. The patient was treated for a familial hyperlipoproteinemia type IIa. MRI and morphological features are shown and discussed on reviewing the literature.

Fever attributed to the use of hydroxyurea.

We report on three patients who developed fever after starting treatment with the anti-neoplastic agent, hydroxyurea. Fever occurred within 5 days to 3 weeks after starting treatment. In all cases the causal relationship between fever and use of hydroxyurea was demonstrated by spontaneous recovery after drug withdrawal and was confirmed by recurrence of fever after rechallenge. Other causes were excluded. Fever was accompanied by rash, gastro-intestinal and pulmonary symptoms, and arthralgia. Physicians should be aware of the fact that unexplained fever may be caused by hydroxyurea.

Tomography of the lamina dura.

Tomographic technics are based on the principle that when the X-ray source is moved in relation to the object the speed of the projection of different parts of the object on a plane will be different. By selecting the projections which have a certain speed, an image of a selected plane of the object can be obtained. Two principles have to be considered: 1. the image of a curved surface will only show the surface area where the rays form a tangent to the surface; 2. in tomography the blurring of the image increases with an increase of the tomographic angle and the distance of the object to the plane in focus. The image formation of curved bony surfaces, such as the lamina dura, is discussed in detail. The specific properties of the spatial model of the lamina dura requires another approach to explain the image formation. Diagrams and graphs illustrate the effect of the tomographic movement of the X-ray source on the movement of the projected image. Limits for the misalignment permitting an interpretable image are given, as well as an explanation of the images obtained when these limits are exceeded.

Influence of anesthesia on autoregulation of the cerebral blood flow.

Autoregulation of the cerebral blood flow is a wellknown fact. In normal man the arterial pressure can vary from 80 mm Hg to 150 mm Hg without a change in the normal cerebral blood flow of 50 ml/100 g/min. The mechanism which is responsible for this autoregulation is not clearly understood. Several theories were proposed to explain this phenomenon. 1. The tissue pressure increases with an increase of the arterial pressure. A mechanical process should neutralize an increase of the cerebral blood flow. 2. The metabolic theory says that a decrease of the blood pressure, without a change of metabolism, involves an increase of the PaCO2, and a decrease of the PaO2. Those two factors provoke a decrease of the vascular tone. 3. The myogenic theory explains autoregulation by the fact that a change of the transmural pressure in the small vessels, involves a change in the activity of the smooth muscles of the vessels. 4. The exact mechanism of the autonomic nervous system in the autoregulation of the cerebral blood flow is still obscure. In some pathological conditions autoregulation is completely lost or is functioning not optimal: hypoxia, hypercapnia and brain contusion. We have measured the cerebral blood flow before and after an intravenous injection of 5 mg thiopental (Pentothal) on occasion of a carotid angiography in man. We noticed a decrease of the cerebral blood flow and at the same moment a decrease of the arterial pressure. We thought that maybe barbiturates could influence autoregulation. Our results could not prove this hypothesis. For ethical reasons we could not make the necessary measurements to prove or to reject this hypothesis (i.e. intracranial pressure, deep controlled hypotension). In the literature there are arguments which support this hypothesis although most workers found an intact autoregulation after a barbiturate anesthesia. Some workers saw that the increase of the cerebral blood flow by increasing the PaCO2 was depressed by barbiturates and exhausted by halothane and cyclopropane. As autoregulation is a more vulnerable mechanism than CO2 reactivity as seen in clinical situations, it could be true that anesthetics do influence autoregulation.

Study of the cerebral blood flow in patients with brain lesions under anesthesia.

The influence of thiopental (Pentothal) on cerebral blood flow was studied by means of ten scintillationcounters in man on occasion of a carotid angiography. The patients received a basic anesthesia with 30% oxygen, 70% nitrous oxide and pancuronium bromide. When the anesthesia was stabilised, thiopental was given (4 mg/kg). The influence of barbiturates on autoregulation is discussed.

Influence of piracetam and etiracetam compared to placebo, on rCBF and parameters of brain metabolism.

On occasion of a carotid angiography in man, regional cerebral bloodflow (rCBF) was measured before and after the injection of thiopental 5 mg/kg I.V. A significant decrease of rCBF was found after thiopental, in a previous study, due to a decrease of the brainmetabolism. To study the influence of piracetam and of etiracetam on this decrease of rCBF, 22 patients received intravenously the evening before the investigation 4 g piracetam or 4 g etiracetam or placebo, as well in the morning before the investigation and 30 minutes before the injection of thiopental. Besides the rCBF also other parameters were measured: arterial pressures, cardiac output, heart rate, as well as blood gases, glucose, lactate and pyruvate in the arterial blood and the cerebral venous blood, and blood gases in the mixed venous blood. There was no influence on the decrease of rCBF neither in the piracetam or etiracetam group, compared to the placebogroup. A few scarce minor changes were seen in the other measured parameters.

Influence of etomidate, a new short acting anesthetic agent, on cerebral blood flow in man.

Cerebral blood flow was measured by means of a ten channel cerebrograph. This investigation was done after a corotid angiography; 2 to 3 miCi of Xenon133 was injected in the internal carotid artery. Beside CBF we measured arterial bloodpressures, heart rate, stroke volume, cardiac output, central venous pressures, blood gases and glucose in arterial blood, blood gases and glucose in the bulbus of the internal jugular vein and blood gases in mixed venous blood. In most regions CBF decreased significantly after Etomidate. The other parameters did not change. Only the heartrate slowed significantly.

Controlled hypotension with fentanyl and halothane in neurosurgery. A clinical evaluation.

An anesthesia technique is described for clipping off a cerebral aneurysm. The patients are premedicated with Thalamonal and atropine. For induction is given: thiopental (Pentothal) 4 mg/kg and pancuronium (Pavulon) 0.1 mg/kg. Subsequently fentanyl 7 micrograms/kg and dehydrobenzperidol 0.25 micrograms/kg is given intravenously. The patient is moderately hyperventilated (PaCO2 30-35 mm Hg) with an O2/N2O gasmixture. Through a second intravenous infusion fentanyl (20 ml fentanyl dissolved in 500 ml glucose 10%) is given continuously to obtain a good painrelief during the whole procedure. Those conditions eliminate almost each cause of an increase of the blood pressure. Once the dura meter is opened, halothane is administered in a concentration between 0.5% and 3% to lower the mean arterial pressure to 60 mm Hg. Within 15 minutes the blood pressure is on the desired level. After clipping off the aneurysm, halothane is stopped and the blood pressure regains its normal level. Postoperatively the patient is ventilated during 24 hours (moderate hyperventilation). To prevent an increase of the blood pressure, the administration of the fentanyl solution is continued. Indeed, the blood pressure may not be allowed to increase because the autoregulation of the CBF is markedly disturbed after a hypotension. This technique has been used in 7 patients.

Jugular bulb oximetry: review on a cerebral monitoring technique.

Jugular bulb oximetry is the first available continuous monitoring method estimating the adequacy of cerebral perfusion. Despite its major technical as well as methodological shortcomings the information on the oxygen supply to demand balance of the brain seems most valuable. Especially the deleterious consequences of systemic variations (mainly concerning arterial blood pressure and CO2-tension) on the diseased brain are revealed by jugular bulb saturation values. The prevention and/or the early detection of these systemic secondary insults could have important implications as to final neurological outcome. Jugular bulb oximetry could also guide specific intracranial antihypertensive treatment, as it may reveal the pathophysiological mechanisms behind intracranial hypertension with regard to the status of cerebral perfusion (cerebral hyperemia or cerebral hypoperfusion). These insights might increase the efficacy of all treatments available for intracranial hypertension.

Operative closure of patent ductus arteriosus in the neonatal intensive care unit.

Preterm infants undergoing surgical closure of patent ductus arteriosus are usually critically ill and are suffering from many concomitant diseases. The high risk of increased morbidity in transferring them from the neonatal intensive care unit (NICU) to a distant operating room is generally recognized. For this reason we report our experience in 33 premature infants with patent ductus arteriosus who have been operated in the NICU over a six-year period. There were no operative or immediate postoperative deaths and the 30 days hospital mortality was 6%. Based upon these findings we can confirm that operative closure of PDA can be performed safely in the NICU.

[Poisoning with amitraz, an agricultural anti-ectoparasitic agent]. / Een intoxicatie met amitraz, een agrarisch anti-ectoparasiticum.

A mentally handicapped male aged 22 years ingested 25-100 ml of the agricultural anti-ectoparasite product amitraz (Taktic) (at most 12.5 g amitraz), and went into coma approx. one hour later (Glasgow coma score: 3). Gastric lavage was performed and activated charcoal and sodium sulphate deposited in the stomach. Product information could be obtained from the manufacturers in the United Kingdom with some trouble, 1.5 hours after admission. It was striking how little information is available concerning the toxicity of agricultural products. Patient had recovered the next day; he was discharged three days after admission. Blood assay 1.5 hours after ingestion revealed a concentration of amitraz plus metabolites of 3.7 micrograms/ml; when the patient came out of coma it was < 0.67 microgram/ml.

[Tuberculosis of the larynx]. / Tuberculose in de larynx.

Laryngeal tuberculosis was diagnosed in two men, a 73-year-old man Dutch by birth and a 40-year-old one Turkish by birth. In the former patient it was probably primary tuberculosis, in the latter secondary (he had lung tuberculosis as well). The clinical picture was highly suggestive of laryngeal carcinoma in both patients. They both recovered with chemotherapy. Laryngeal tuberculosis may mimic laryngeal carcinoma. The diagnosis is based on Ziehl-Neelsen staining, culture and polymerase chain reaction (PCR) on Mycobacterium tuberculosis. Because laryngeal tuberculosis is highly infectious, the patient has to be nursed in isolation and people in his or her environment have to be screened. The response of laryngeal tuberculosis to chemotherapy is good.