Rate of tree carbon accumulation increases continuously with tree size.

Forests are major components of the global carbon cycle, providing substantial feedback to atmospheric greenhouse gas concentrations. Our ability to understand and predict changes in the forest carbon cycle--particularly net primary productivity and carbon storage--increasingly relies on models that represent biological processes across several scales of biological organization, from tree leaves to forest stands. Yet, despite advances in our understanding of productivity at the scales of leaves and stands, no consensus exists about the nature of productivity at the scale of the individual tree, in part because we lack a broad empirical assessment of whether rates of absolute tree mass growth (and thus carbon accumulation) decrease, remain constant, or increase as trees increase in size and age. Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree. The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree's total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density. Our results resolve conflicting assumptions about the nature of tree growth, inform efforts to undertand and model forest carbon dynamics, and have additional implications for theories of resource allocation and plant senescence.

Under-reporting giardiasis: time to consider the public health implications.

Giardiasis is a treatable disease, caused by the flagellated protozoan parasite, Giardia duodenalis (G. duodenalis). It is one of the most common enteric parasites found globally to cause gastrointestinal disturbances, and infections may result in long-term irritable bowel syndrome-like symptoms. It is a common misconception that giardiasis is associated with foreign travel, which results in locally acquired cases in the UK being underdiagnosed. This report highlights the findings from one large Scottish Health Board, arising from a change in testing methodology, which resulted in the screening of all stools submitted for enteric investigations for G. duodenalis. Previous selection criteria were restricted to patients with a travel history to specific regions of the world, or on the basis of certain clinical details. In this report, clinical details were recorded from samples shown to be positive using two methods: an ELISA-based antigen detection assay and microscopy. Clinical details were assessed for a total of 28 laboratory-confirmed positive cases against the original selection criteria. Twenty-six cases (93%) would have been excluded from Giardia testing if the previous selection criteria had been applied. Although nine cases stated foreign travel, only two had been to regions deemed to be 'high risk'. Therefore, those seven cases that travelled to perceived 'low-risk' regions would have been excluded from testing for this reason. This summary highlights the need for significant improvements to the selection criteria for Giardia testing. Laboratories should be encouraged towards the testing of all routinely submitted stools for this neglected pathogen to ensure cases that are acquired locally are properly identified and treated effectively.

A synthetic review of notoedres species mites and mange.

Notoedric mange, caused by obligately parasitic sarcoptiform Notoedres mites, is associated with potentially fatal dermatitis with secondary systemic disease in small mammals, felids and procyonids among others, as well as an occasional zoonosis. We describe clinical spectra in non-chiropteran hosts, review risk factors and summarize ecological and epidemiological studies. The genus is disproportionately represented on rodents. Disease in felids and procyonids ranges from very mild to death. Knowledge of the geographical distribution of the mites is highly inadequate, with focal hot spots known for Notoedres cati in domestic cats and bobcats. Predisposing genetic and immunological factors are not known, except that co-infection with other parasites and anticoagulant rodenticide toxicoses may contribute to severe disease. Treatment of individual animals is typically successful with macrocytic lactones such as selamectin, but herd or wildlife population treatment has not been undertaken. Transmission requires close contact and typically is within a host species. Notoedric mange can kill half all individuals in a population and regulate host population below non-diseased density for decades, consistent with frequency-dependent transmission or spillover from other hosts. Epidemics are increasingly identified in various hosts, suggesting global change in suitable environmental conditions or increased reporting bias.

Evaluation of complications and feasibility of indwelling epidural catheter use for post-operative pain control in dogs in the home environment.

AIMS: The objective of this study was to describe the use of indwelling epidural catheters post-operatively in dogs in a home environment, and to report associated complications. METHODS: Dogs undergoing surgical procedures of the hind limb (n=83) were included in the study and were administered 0.05 or 0.10 mg/kg epidural morphine via an indwelling epidural catheter every 6 hours. Data compiled relating to catheter placement included time of placement, ease of placement and problems encountered, number of attempts of placement, and individual placing the catheter. A client questionnaire was provided to evaluate side effects, complications, pain, and ease of use of the epidural catheter system after discharge from the hospital and catheter removal at home. Side effects were compared between the dogs receiving 0.05 or 0.1 mg/kg epidural morphine. RESULTS: The most common patient complication was abnormal urination patterns (32/82, 39%); specifically dribbling urine where laying, emptying the entire bladder where laying, not urinating for extended periods of time, and taking a longer time to pass urine were reported. There were no significant differences in the number or types of side effects reported in either dosing group. The most common technical issues reported by owners were difficulty getting the needle into the injection port (10/81, 12%) and removing the adhesive covering keeping the epidural catheter system in place (19/78, 24%). There were no reports of inflammation or discharge at the catheter site in any of the dogs. Of the respondents surveyed, 76/79 (97%) found the epidural catheter system easy to use at home in the post-operative period. CONCLUSIONS: Indwelling epidural catheters are a feasible method of administration of post-operative analgesia in the immediate post-operative period in the home environment and were associated with only a few minor complications in this population.

The effects of foot reflexology on anxiety and pain in patients with breast and lung cancer.

PURPOSE/OBJECTIVES: To test the effects of foot reflexology on anxiety and pain in patients with breast and lung cancer. DESIGN: Quasi-experimental, pre/post, crossover. SETTING: A medical/oncology unit in a 314-bed hospital in the southeastern United States. SAMPLE: Twenty-three inpatients with breast or lung cancer. The majority of the sample were female, Caucasian, and 65 years or older; had 12 or fewer years of education and an annual income of $20,000 or more; and were receiving regularly scheduled opioids and adjuvant medications on the control and intervention day. METHODS: Procedures included an intervention condition (foot reflexology to both feet for 30 minutes total by a certified reflexologist) and a control condition for each patient (with at least a two-day break). No changes were made in patients' regular schedule or medications. MAIN RESEARCH VARIABLES: Anxiety and pain. FINDINGS: Following the foot reflexology intervention, patients with breast and lung cancer experienced a significant decrease in anxiety. One of three pain measures showed that patients with breast cancer experienced a significant decrease in pain. CONCLUSIONS: The significant decrease in anxiety observed in this sample of patients with breast and lung cancer following foot reflexology suggests that this may be a self-care approach to decrease anxiety in this patient population. IMPLICATIONS FOR NURSING PRACTICE: Professionals and lay people can be taught reflexology. Foot reflexology is an avenue for human touch, can be performed anywhere, requires no special equipment, is noninvasive, and does not interfere with patients' privacy.

Creative strategies for updating knowledge on sexually transmitted diseases.

Updating knowledge is important in maintaining effective nursing competency. The hectic pace of health care delivery in the 1990s does not always allow for attending day-long continuing education sessions. This article presents creative teaching-learning strategies that are self-paced, interesting, and less time intensive, designed to update nurses on sexually transmitted diseases.

A comparison of nurse and patient: perceptions of postsurgical pain.

In this study, the nurses' and patients' perceptions of a patient's postsurgical pain were compared. Responses to the McGill Pain Questionnaire, Present Pain Intensity (MPQ-PPI) and the Visual Analogue Scale (VAS) indicated that nurses scored patients lower on the average than patients scored themselves, both before pain medication and after pain relief. As expected, the scores on the MPQ-PPI and VAS were highly correlated, except for patients' scores before administration of medication.

CT appearances of rounded atelectasis.

Five patients examined with CT had lesions fulfilling criteria for a diagnosis of rounded atelectasis (RA) and these were managed without biopsy. In three patients unsuspected contralateral lesions were identified as RA variants, and one of these was biopsied at thoracotomy and proved to be benign. All patients remain well at 6-22 months follow-up. We concur with recent reports that there is a spectrum of CT appearances of RA and that even atypical lesions seldom need further investigation. We also suggest that the appearances of some atypical lesions add support for the fibrosing theory of pathogenesis of RA.

Hepatic focal nodular hyperplasia: colour Doppler ultrasound can be diagnostic.

Focal nodular hyperplasia (FNH) is a rare, benign, hepatic mass lesion that is usually found in young adult females. It is sometimes an incidental finding on abdominal sonography or computed tomography. Its appearance on these studies is not characteristic however, thereby creating a diagnostic problem. This report is of a case which showed a centrifugal, spokewheel pattern of pulsatile blood supply on colour Doppler US. This finding, we suggest, is sufficiently diagnostic to avoid the need for further investigation in some patients, and to direct further imaging more appropriately in others.

Invasive locomotory behaviour between malignant human melanoma cells and normal fibroblasts filmed in vitro.

Explants of human malignant melanoma (MM96), normal adult human skin fibroblasts (HSF) and embryonic chick ventricle were confronted in pairs. The 2 outwandering populations in each confrontation eventually met in a situation where each could potentially invade the other. The human explants were artificially prepared from dissociated cells. The primary objective of the study was to compare the relative invasive capacities of the malignant and nonmalignant human cell populations against a standard population of chick heart fibroblasts (CHF). Relative invasiveness was also compared for (a) malignant human melanoma cells against human and avian fibroblasts; (b) the 2 different fibroblast populations against MM96; and (c) the 2 fibroblast populations against each other. Time-lapse films were prepared for each confrontation. Each cell population was also filmed in a free or unconfronted state. The films were analysed in terms of (a) cell speeds in relation to numbers of contacts; (b) the net radial outward velocity; (c) directional frequencies of movements; and (d) cell behavior resulting from heterologous collisions. Replicate cultures were fixed and stained 24--40 h after junction. Measurements from these indicated relative distances travelled by each population towards the opposing population and towards free space. Nuclear overlap and population density measurements were also recorded. MM96 cells invaded the standard chick fibroblast population but eventually encountered moderate obstruction. Invasion was mainly by oriented movement between successive pairs of chick cells. Contact paralysis of ruffling of MM96 was not seen. Human fibroblasts did not invade the CHF population. They were contact inhibited by chick cells and typically reversed their direction of movement. MM96 cells invaded the human fibroblast population without obstruction. They were not usually inhibited by HSF and several different pathways for locomotory invasion, including overlapping, were involved. Cells of both fibroblast populations were contact inhibited by leading-edge collisions with MM96 cells. Fibroblast invasion of MM96 was by underlapping of orthogonally oriented, bipolar melanocytes or dendritic processes. Human fibroblasts were less obstructed than chick fibroblasts during invasion of MM96. Initiation of invasion of HSF by chick cells was apparently orientation dependent. Invasion by CHF was assisted by the alignment, morphology and contact-mediated withdrawal of the human cells. Heterologous contact inhibition was not apparently defective for either cell type. In all confrontations involving both malignant and non-malignant cells, the extent and pattern of invasion could be related to apparent deficiencies in heterologous contact inhibition of locomotion.

Pain measurement: a comparison using horizontal and vertical visual analogue scales.

The McGill Pain Questionnaire (MPQ) is widely used in assessing a variety of pain problems. MPQ has been found to be sensitive enough to detect differences in pain relief and differences between acute and chronic pain. It requires, however, 5 to 10 minutes to administer. Because of this time factor, the Short-Form McGill Pain Questionnaire (SF-MPQ) was developed. A visual analogue scale (VAS) was not included in the original MPQ but is part of the SF-MPQ. Studies addressing the best way to present a VAS suggest that a vertical line is easier for patients to see; however, the VAS on the SF-MPQ is a horizontal line. This study examined the relationship between SF-MPQ scores with both the horizontal and vertical VAS.

Has lymphography a role in early stage testicular germ cell tumours?

A retrospective study was performed of 183 newly diagnosed seminoma cases and 73 newly diagnosed non-seminomatous germ cell tumours (NSGCT) presenting from 1985 to 1989 to a tertiary referral cancer hospital. The purpose was to assess the contribution of bipedal lymphography (LG) to the management of these patients. As the main value of LG is in detecting small retroperitoneal lymph node (LN) metastases, analysis concentrated upon early stage disease, specifically N0 and N1a LN disease. Comparison between LG results, abdominopelvic computed tomography (APCT), final clinical stage and treatment outcome was performed. We found that with the LG and APCT criteria used (filling defects > 2 mm and LN diameter > 20 mm, respectively), LG was much more sensitive in disease detection. However, with modern techniques APCT can reliably detect disease 10 mm or greater. In addition, tumour marker status, primary tumour vascular invasion status and initial clinical examination were each more important in staging NSGCT disease than LG alone. Thus, LG is now rarely used in our institution but we will have to monitor our excellent survival data to confirm that this change in policy is warranted.

New permanent endocardial atrial J lead: implantation techniques and clinical performance.

The potential benefits of pacing systems which restore A-V synchrony have long been recognized. However, availability of atrial leads which are easily implanted and which consistently perform well has been limited. A new version of the silicone rubber tined J leads is now available. Changes were made in the insulation material, conductor configuration, tine configuration, and a J memory coil was added. After over three years of use in 100 patients, we conclude that these leads are easier to implant than previous atrial leads, and that they demonstrate excellent clinical performance.