The constructal-law physics of why swimmers must spread their fingers and toes.

Here we show theoretically that swimming animals and athletes gain an advantage in force and speed by spreading their fingers and toes optimally. The larger force means larger body mass lifted and greater speed, in accord with the constructal theory of all animal locomotion. The spacing between fingers must be twice the thickness of the boundary layer around one finger. This theoretical prediction is confirmed by computational fluid dynamics simulations of flow across two and four cylinders of diameter D. The optimal spacing is in the range 0.2D-0.4D, and decreases slightly as the Reynolds number (Re) increases from 20 to 100. For example, the total force exerted by two optimally spaced cylinders exceeds by 53% the total force of two cylinders with no spacing when Re=20. These design features hold for both time-dependent and steady-state flows.

Genetic association study in nasal polyposis.

BACKGROUND AND OBJECTIVES: Nasal polyposis (NP) is a chronic inflammatory disease of the upper airways with a variable clinical course and unknown pathogenesis that often coexists with other conditions. Considering the possibility of genetic predisposition, we decided to analyze whether polymorphisms in LTC4S, CYSLTR1, PTGDR, and NOS2A were associated with NP. METHODS: The study population comprised 486 Caucasian individuals. Polyposis and aspirin intolerance were diagnosed following the recommendations of the European Position Paper on Rhinosinusitis and Nasal Polyps. Genotypes were determined using polymerase chain reaction amplification and direct sequencing. RESULTS: The -444A > C LTC4S polymorphism was significantly associated with NP and atopy (P = .033) and with NP and atopic asthma, (P =.012). In addition, a significant association was found when the (CCTTT) repetition of the NOS2A gene was present more than 14 times in patients with NP and asthma (P = .034), in patients with polyposis and intolerance to nonsteroidal anti-inflammatory drugs (P = .009), and in patients with the aspirin triad (P = .005). The PTGDR diplotype CCCT/CCCC (-613CC, -549CC, -441CC and -197TC) was more frequent in patients with NP (P = .043), NP with asthma (P = .013), and the aspirin triad (P = .041). CONCLUSIONS: NP was associated with specific polymorphisms only when it occurred with related phenotypes. Our results suggest that this genetic background plays a more relevant role in the development of the associated clinical features of nasal polyposis than in simple polyposis.

Convergent Evolution of Boats with Sails.

This article unveils the geometric characteristics of boats with sails of many sizes, covering the range 102-105 kg. Data from one hundred boat models are collected and tabulated. The data show distinct trends of convergent evolution across the entire range of sizes, namely: (i) the proportionality between beam and draft, (ii) the proportionality between overall boat length and beam, and (iii) the proportionality between mast height and overall boat length. The review shows that the geometric aspect ratios (i)-(iii) are predictable from the physics of evolution toward architectures that offer greater flow access through the medium.

Unifying constructal theory of tree roots, canopies and forests.

Here, we show that the most basic features of tree and forest architecture can be put on a unifying theoretical basis, which is provided by the constructal law. Key is the integrative approach to understanding the emergence of "designedness" in nature. Trees and forests are viewed as integral components (along with dendritic river basins, aerodynamic raindrops, and atmospheric and oceanic circulation) of the much greater global architecture that facilitates the cyclical flow of water in nature (Fig. 1) and the flow of stresses between wind and ground. Theoretical features derived in this paper are: the tapered shape of the root and longitudinally uniform diameter and density of internal flow tubes, the near-conical shape of tree trunks and branches, the proportionality between tree length and wood mass raised to 1/3, the proportionality between total water mass flow rate and tree length, the proportionality between the tree flow conductance and the tree length scale raised to a power between 1 and 2, the existence of forest floor plans that maximize ground-air flow access, the proportionality between the length scale of the tree and its rank raised to a power between -1 and -1/2, and the inverse proportionality between the tree size and number of trees of the same size. This paper further shows that there exists an optimal ratio of leaf volume divided by total tree volume, trees of the same size must have a larger wood volume fraction in windy climates, and larger trees must pack more wood per unit of tree volume than smaller trees. Comparisons with empirical correlations and formulas based on ad hoc models are provided. This theory predicts classical notions such as Leonardo's rule, Huber's rule, Zipf's distribution, and the Fibonacci sequence. The difference between modeling (description) and theory (prediction) is brought into evidence.

[What medication should be prescribed to a patient with coeliac disease?] / ¿Qué medicamento prescribiría a un paciente con enfermedad celiaca?

Coeliac disease is a permanent intolerance to gluten proteins from wheat, rye, barley and triticale. Although strict adherence is complicated, the only effective treatment is a gluten-free diet throughout life. Some drugs contain starch as an excipient, and there is a risk related to the gluten content, which must be avoided in these patients. Current legislation requires the analysis of the protein content of wheat starch, or the absence of starches from another source where rice, maize, or potato starches are used as excipients. But, it does not specify that reference should be made to traces of gluten that are residues of the process of production of the active ingredient. As regards the case described, there needs to be awareness of the importance of adequately informing patients and reviewing/updating current legislation to ensure the safe use of drugs.

Liquid-based cytology and cell block immunocytochemistry in veterinary medicine: comparison with standard cytology for the evaluation of canine lymphoid samples.

Liquid-based Cytology (LBC) consists of immediate wet cell fixation with automated slide preparation. We applied LBC, cell block (CB) and immunocytochemistry to diagnose canine lymphoma and compare results with conventional cytology. Samples from enlarged lymph nodes of 18 dogs were collected and fixed in preservative solution for automated slide preparation (LBC), CB inclusion and immunophenotyping. Two CB techniques were tested: fixed sediment method (FSM) and agar method (AM). Anti-CD79a, anti-Pax5, anti-CD3 and anti-Ki67 were used in immunocytochemistry. LBC smears showed better nuclear and nucleolar definition, without cell superposition, but presented smaller cell size and worse cytoplasmic definition. FSM showed consistent cellular groups and were employed for immunocytochemistry, while AM CBs presented sparse groups of lymphocytes, with compromised analysis. Anti-Pax-5 allowed B-cell identification, both in reactive and neoplastic lymph nodes. Our preliminary report suggests that LBC and FSM together may be promising tools to improve lymphoma diagnosis through fine-needle aspiration.

Evaluation of cerebral function after carotid endarterectomy.

Neuroimaging methods have failed to disclose correlation between degree of cerebral atrophy and blood flow in carotid artery stenosis patients. Moreover, intellectual improvement after carotid endarterectomy does not correlate fully with neuroimaging data in such patients. We performed brain electrical activity mapping and psychological testing before and 4 weeks after operation in 28 patients with symptomatic, high-grade, carotid stenosis. Postoperatively, electroencephalographic (EEG) mean frequency and absolute theta power improved significantly (p < 0.01). Mean frequency increased >1 Hz in most areas while power decreased dramatically, mainly because of resolution of high-voltage foci in 8 patients. Differences were conspicuous in both frontal lobes irrespective of the operated side, which suggests changes in perfusion affecting the whole brain. This is a positive effect of endarterectomy. Mini-Mental test and Set Test for verbal fluency had a positive correlation with the qEEG changes. Quantitative EEG as a measure of cerebral function has disclosed discriminative improvement in the early postoperative period. Our results support the thesis of improvement subsequent to endarterectomy.

[Recurrent digestive hemorrhage as a complication of an intraduodenal diverticulum]. / Hemorragia digestiva recidivante como complicación de un divertículo intraduodenal.

Intraluminal duodenal diverticulum (IDD) is a rare congenital anomaly, which usually causes symptoms in adulthood. We report a 39-year-old woman, who presented several episodes of upper gastrointestinal bleeding and who was successfully treated with surgery. The clinical presentation, diagnosis and treatment of the 56 cases published in the English and Spanish literature from 1975 to 1998 are reviewed.

[Lumbar puncture and early neuroimaging in complex febrile seizures. Report of a case of shaken infant syndrome]. / Punción lumbar y neuroimagen precoz en las crisis febriles complejas. A proposito de un caso de síndrome de lactante sacudido.

INTRODUCTION: Febrile convulsions are one of the most frequent pathologies seen in paediatric emergencies. The diagnosis of febrile seizures is clinico evolutionary and is easily established once the acute process is overcome and a normal state is restored in the child. The differential diagnosis is established with the processes that associate fever and convulsions in children between the ages of 1 month and 6 years, many of which require specific treatment. Certain complementary examinations, essentially a blood test, lumbar puncture and neuroimaging, are needed to identify them. Shaken infant syndrome is a form of physical abuse which includes the presence of intracranial traumatic injury, retinal haemorrhage and, in general, the absence of other physical signs of traumatic injury in the child. CASE REPORT: An 8 month old infant who presented a convulsive seizure on the left side of the body which coincided with an axillary temperature of 38 C that remitted with intravenous diazepam 40 minutes after onset. An early cranial computerised tomography (CT) scan led to a diagnosis of shaken infant syndrome. DISCUSSION: This case constitutes an argument in favour of performing an early cranial CT scan in complex febrile convulsions and in prolonged or partial non provoked seizures. We highlight the risks involved in performing a lumbar puncture in the absence of suspected non complicated acute bacterial meningitis. The diagnostic usefulness of an early CT scan in diagnosing such an important problem as shaken infant syndrome must also be noted, due to the risk of repetition and its high morbidity and mortality rates.

Evolution: why all plumes and jets evolve to round cross sections.

Turbulent curtains of smoke rise initially as flat plumes and, above a certain height, they become round plumes. The same evolution of cross-sectional shape is exhibited by jets issuing from flat nozzles. Here we predict based on principle that all such flows should evolve their cross-sectional shapes from flat to round (and not the other way) at a critical distance downstream, which is predictable. The principle is that the prevailing flow architecture provides greater access to the flow of momentum from the moving core (plume, jet) to the still surroundings. For turbulent plumes and jets, the transition distance scales with the long dimensions (L) of the two-dimensional (flat) heat sources and nozzles that drive them. For laminar jets, the transition distance scales with L Re, where Re is the Reynolds number based on nozzle velocity and the smaller dimension of the nozzle cross section. These predictions are confirmed by full numerical experiments of the three-dimensional flow fields of turbulent and laminar jets covering the Re range 10-10(4).

Liver transplanted patients with donors older than 60 years require more hospital resources.

BACKGROUND: The increasing utilization of organs from older donors to fulfill the increasing demand for transplantation has been associated with an increased complication rate and shorter graft survival. Nevertheless, few studies have evaluated the impact of these donors on resource utilization. We sought to evaluate hospital resource utilization during the first year after liver transplantation among patients receiving a liver from a donor >60 years versus a younger donor. METHODS: This prospective study evaluated 149 consecutive liver transplantations performed in our center between 2000 and 2005. We divided the patients into 2 groups according to the donor's age; group A <60 and group B, ≥ 60 years. The follow-up was for the first year. Herein we have reported data related to resource utilization, such as number and length of stay hospitalizations, length of ICU stay; surgical and diagnostic procedures including ultrasounds, cholangiography, computed tomography or magnetic resonance imaging, as well as external consultations. RESULT: Group B patient required a greater number of hospitalizations (2.7 ± 2.4 vs 1.7 ± 1.5; P = .006), and a longer length of initial stay (37.5 ± 20.9 vs 27.8 ± 17.5 days; P = .012). There were no differences between groups concerning diagnostic and surgical procedures or external consultations. CONCLUSION: Patients transplanted from donors >60 years required more hospital resources in the first year after transplantation.

Neurophysiological methods testing the psychoneural basis of attention deficit hyperactivity disorder.

Theories concerning the etiology of attention deficit hyperactivity disorder have evolved from the 1950s, when it was believed that an injury to or dysfunction of the diencephalon was the cause of the syndrome, to the present day, when delayed brain maturation is postulated as an explanation. Delay in laying down myelin can be investigated by newly developed techniques like computerized EEG and transcranial magnetic stimulation. In this study, a group of 15 children 3-7 years of age suffering from attention deficit were investigated using both methods in combination and were compared to a control group of 23 age-matched normal children. On the computerized EEG spectral analysis significant differences to the control group were found in areas O1 and O2 (P < 0.05, Student's t-test). With transcranial magnetic stimulation, the overall difference in right/left stimulation was statistically significant (P < 0.001). The results suggest delayed myelination at the brain stem reticular formation where the alpha rhythm is activated and at the corticospinal pathway as parts of a widespread involvement.

Helicobacter pylori stimulates pepsinogen secretion from isolated human peptic cells.

BACKGROUND: Different acid and peptic related gastroduodenal diseases are associated with both increased gastric secretion and Helicobacter pylori infection. Patients with H pylori associated gastritis or duodenal ulcer have increased serum pepsinogen levels which decrease after eradication. The mechanisms of H pylori induced gastric mucosal damage are not completely understood. AIM: To determine the effects of H pylori on pepsinogen secretion from isolated human peptic cells. METHODS: Dispersed human peptic cells were prepared from endoscopically obtained biopsy specimens after collagenase digestion, mechanical disruption, and density gradient centrifugation. H pylori was obtained from gastric biopsies (antrum and body), and cultured in non-selective and selective media. Isolates of H pylori were used at different concentrations (1 - 20 x 10(6) colony forming units (cfu)). RESULTS: H pylori (10(6) - 2 x 10(7) cfu) increased basal pepsinogen secretion in a concentration dependent manner. This stimulus was not observed with Escherichia coli. The increased secretion was in addition to that observed with 0.1 mM histamine and 0.1 mM dibutyryl-cyclic adenosine monophosphate. However, H pylori did not affect either carbamylcholine (0.1-10 microM) or cholecystokinin (1 microM) stimulated pepsinogen secretion. Addition of the nitric oxide synthase inhibitor N(w)-monomethyl-L-arginine (1 mM) inhibited H pylori induced cGMP generation and pepsinogen secretion, which were also reduced in the absence of extracellular calcium. H pylori induced pepsinogen secretion was not affected by the absence/presence of the cagA gene. CONCLUSIONS: H pylori increases pepsinogen secretion from human peptic cells through a calcium and nitric oxide mediated intracellular pathway. This effect is independent of the H pylori virulent cagA gene, and may be a mechanism of H pylori induced gastric mucosal damage.

Cytokine effects on pepsinogen secretion from human peptic cells.

BACKGROUND: Different cytokines, including epidermal growth factor (EGF) and interleukin 1 beta (IL 1 beta), participate in the pathogenesis of gastric mucosal damage and repair by means of different mechanisms that are either paracrine or autocrine in nature. AIMS: To study whether EGF and IL 1 beta affect pepsinogen secretion in vitro. METHODS: Dispersed human peptic cells were prepared from endoscopically obtained biopsy specimens after collagenase digestion, mechanical disruption, and density gradient centrifugation. RESULTS: EGF dose dependently increased basal pepsinogen secretion and mitogenic concentrations (0.1 nM) of EGF induced submaximal stimulation. Similar effects were observed with transforming growth factor alpha. EGF effects on pepsinogen secretion were in addition to that induced by CCK-OP and db-cAMP stimulated pepsinogen secretion. EGF stimulated pepsinogen secretion was completely inhibited by a human immunospecific EGF receptor antibody and reduced by both genistein and tyrphostin-25, two different tyrosine kinase inhibitors. IL 1 beta does not affect basal, CCK-OP or acetylcholine stimulated pepsinogen secretion. However, IL 1 beta dose dependently inhibited db-cAMP and histamine stimulated pepsinogen secretion. CONCLUSIONS: These results show that both EGF and IL 1 beta modulate human pepsinogen secretion in vitro and suggest that the paracrine effects of these cytokines on pepsinogen secretion might be involved in some pathological conditions of damage and inflammation of the gastric mucosa.

[Psychopharmaceuticals in primary care: prescription quality]. / Psicofármacos en atención primaria: calidad de la prescripción.

OBJECTIVE: Using criteria based on the bibliography, to assess drugs prescription in a Health Centre, in order to put forward corrective measures in line with the defects identified. DESIGN: Descriptive and retrospective study. SETTING: Santa Maria de Benquerancia Health Centre (Toledo). PARTICIPANTS: A sample of 40% of the clinical records of patients over 14 produced records of patients treated with drugs for psychic disorders between October 1990 and October 1991. MEASUREMENTS AND MAIN RESULTS: 248 prescriptions for these drugs were found. The most common diagnoses were: neurotic depression (33.1%), anxiety (25.8%) and insomnia (10.1%). Benzodiazepines made up 78.2% of the prescriptions. Of 8 quality criteria assessed, the compliance level was acceptable by WHO standards except in the recording in the notes of the diagnosis or problem for which the drug was prescribed (74.2% non-compliance); Alprazolam and Triazolam were not considered first-choice benzodiazepines (31.3% non-compliance); and there was 44.5% non-compliance by Primary Care physicians with the non-prescription of anti-psychotic or stimulant MAO inhibitor antidepressants. CONCLUSIONS: Quality-control studies, such as this one, in order to identify problems, to take corrective measures and subsequently assess them, are useful in improving care procedures.

Low frequency of upper gastrointestinal complications in a cohort of high-risk patients taking low-dose aspirin or NSAIDS and omeprazole.

BACKGROUND: There is very little information available on the incidence of complications and on the best prevention therapy in high-risk patients taking non-steroidal anti-inflammatory drugs (NSAIDs) and/or aspirin. Randomized-controlled trials in such patients are rare for ethical reasons. We studied the incidence of gastrointestinal complications in high-risk patients taking long-term low-dose aspirin or non-aspirin-NSAIDs combined with omeprazole in a real-life clinical setting. METHODS: This was a multicentre, prospective and observational study including 247 consecutive high-risk patients who had a clinical indication for long-term treatment with either low-dose aspirin or non-aspirin NSAIDs and omeprazole therapy. The occurrence of gastrointestinal complications was measured. RESULTS: In addition to a recent history of peptic ulcer bleeding, all patients had at least 1 other risk factor and 112 (45.3%) had 3 or more risk factors; 78.9% were taking low-dose aspirin and the remainder non-aspirin NSAIDs. Mean follow-up was 14.6 +/- 10.38 months. Three patients taking low-dose aspirin developed upper gastrointestinal bleeding (1.2%; 95% CI 0.3-3.5; 1.0 event/100 patients/year). This was similar to the rate observed in studies involving non-high-risk patients taking low-dose aspirin and higher than that observed in patients not taking low-dose aspirin. Two additional patients developed a lower gastrointestinal bleeding event (0.81% (0.04%-3.12%); 0.67 events/100 patients/year), which was within the range expected in NSAID users. CONCLUSIONS: The use of omeprazole in the high-risk patient taking low-dose aspirin or NSAIDs seems to be a safe therapeutic approach in this population and is associated with a low frequency of upper gastrointestinal complications.