Asymmetrical voltage response in resonant neurons shaped by nonlinearities.

The conventional impedance profile of a neuron can identify the presence of resonance and other properties of the neuronal response to oscillatory inputs, such as nonlinear response amplifications, but it cannot distinguish other nonlinear properties such as asymmetries in the shape of the voltage response envelope. Experimental observations have shown that the response of neurons to oscillatory inputs preferentially enhances either the upper or lower part of the voltage envelope in different frequency bands. These asymmetric voltage responses arise in a neuron model when it is submitted to high enough amplitude oscillatory currents of variable frequencies. We show how the nonlinearities associated to different ionic currents or present in the model as captured by its voltage equation lead to asymmetrical response and how high amplitude oscillatory currents emphasize this response. We propose a geometrical explanation for the phenomenon where asymmetries result not only from nonlinearities in their activation curves but also from nonlinearites captured by the nullclines in the phase-plane diagram and from the system's time-scale separation. In addition, we identify an unexpected frequency-dependent pattern which develops in the gating variables of these currents and is a product of strong nonlinearities in the system as we show by controlling such behavior by manipulating the activation curve parameters. The results reported in this paper shed light on the ionic mechanisms by which brain embedded neurons process oscillatory information.

Study of frontal hairline patterns in Spanish Caucasian women.

BACKGROUND: Anterior hairline measurements and their possible relationship with androgen levels, sebum production, and skin hydration have not been reported in white Spanish women. MATERIAL AND METHODS: This was a prospective descriptive and analytical observational study conducted on 103 healthy premenopausal white Spanish women recruited from the health staff of Hospital Universitario Virgen Macarena in Seville, Spain. Measurements were made of anterior hairline implantation, sebum levels, and the degree of hydration of the stratum corneum. Androgen levels were also determined in 50 volunteers from this group 3 to 5 days after the end of the menstrual cycle. RESULTS: The mean age of the women was 29.7 years. A widow's peak was observed in 94.17% of the group. The mean dimensions of the widow's peak were a height of 1.01 cm and width of 2.13 cm. The mean hormone levels were within normal limits for our hospital's laboratory with the exception of 17-hydroxyprogesterone, with a mean level of 1.39 ng/mL (range, 0.6-5.9ng/mL; normal limits, 0.15-1.10 ng/mL). The mean prostate specific antigen level was 0.04ng/mL (range 0.02-0.08ng/mL; normal limits, 0.00-0.02ng/mL). CONCLUSIONS: The hairline measurements of the white Spanish women in this study differ from those reported in American women. Knowledge of this normal pattern of anterior hairline implantation can be important in the evaluation of women with female androgenetic alopecia with male pattern, frontal fibrosing alopecia, or other established scarring alopecia seeking a surgical solution by hair transplantation.

Physical workloads of the upper-extremity among workers of the Colombian flower industry.

BACKGROUND: We report the prevalence of symptoms of common upper-limb disorders and describe comprehensively mechanical workloads in a sample of workers of the Colombian flower industry. METHODS: One hundred fifty eight workers from eight flower manufacturers were assessed. Assessments included Borg self-reported exertion and working practices, medical examinations, video-based observations and kinematic and surface muscular activity assessments of upper-limb. RESULTS: Point prevalence of signs and symptoms of CTS, epicondylitis, and De Quervain's disease was 32.9%, 15.2%, and 13.3%, respectively. All tasks are executed on average in wrist extension, ulnar deviation, and high elbow flexion. Average median muscle activity across tasks ranged between 3.6% and 27.3%. Forearm muscles were mainly active. CONCLUSIONS: The occurrence of signs and symptoms of upper-extremity musculoskeletal disorders was high among the sample. The classification and cutting task showed the highest mechanical demands. Interventions in this working population are required and should be directed to allow for muscular rest on regular basis.

Differentiation of self: A scoping review of Bowen Family Systems Theory's core construct.

Bowen Family Systems Theory's central construct, differentiation of self (DoS), is one of the most recognized constructs to systemic researchers and psychology professionals. The present study reviewed the available evidence on DoS from the inception of the construct until July 31, 2020. A scoping review was conducted and a total of 295 primary studies were eligible for inclusion. Literature was categorized according to the hypotheses postulated by Bowen regarding: the associations between DoS and psychological and health outcomes and how DoS stability and similarity in partner levels operate within family systems. Descriptive data regarding studies on the measurement of DoS and in the area of psychotherapy were also compiled. Results revealed that there is ample support for DoS as a predictor of psychological health and marital quality, and that there are positive associations between DoS and better physical health and intergenerational relationships. Results of this review show that there continue to be underexplored hypotheses and a paucity of longitudinal or causal research designs to test the stability of DoS, the intergenerational transmission of DoS, and the efficacy of clinical interventions in modifying DoS to promote optimal well-being. Recommendations and next steps for researchers and practitioners are outlined.

Fiber degradation and carbohydrate production by combined biological and chemical/physicochemical pretreatment methods of lignocellulosic biomass - A review.

Sustainable biorefinery concepts based on lignocellulosic biomass are gaining worldwide research interest because of their inexpensiveness and abundance. The recalcitrance of lignocellulosic biomass poses a major hindrance to enhance biofuel production. Therefore, a pretreatment step is critical to prepare the substrates for the downstream process. Combining pretreatment steps help to lower the severity of the drawbacks of a single pretreatment step. This paper systematically reviews the combined biological and chemical/physicochemical pretreatment based on fiber degradation and sugar yield. An energy-efficient biological pretreatment method combined with a chemical pretreatment that accelerates the pretreatment times has been seen to be efficient for fiber degradation and sugar yields. However, fungal species, culture conditions, biomass type, the severity of chemical pretreatment and the order of sequential pretreatment influences the relative component contents and sugar yield. Even the same biomass from different sources undergoing similar pretreatment conditions could result in a varying amount of digestibility.

A role for antimicrobial peptides in intestinal microsporidiosis.

SUMMARY: Clinical isolates from 3 microsporidia species, Encephalitozoon intestinalis and Encephalitozoon hellem, and the insect parasite Anncaliia (Brachiola, Nosema) algerae, were used in spore germination and enterocyte-like (C2Bbe1) cell infection assays to determine the effect of a panel of antimicrobial peptides. Spores were incubated with lactoferrin (Lf), lysozyme (Lz), and human beta defensin 2 (HBD2), human alpha defensin 5 (HD5), and human alpha defensin 1 (HNP1), alone and in combination with Lz, prior to germination. Of the Encephalitozoon species only E. hellem spore germination was inhibited by HNP1, while A. algerae spore germination was inhibited by Lf, HBD2, HD5 and HNP1, although HBD2 and HD5 inhibition required the presence of Lz. The effects of HBD2 and HD5 on microsporidia enterocyte infection paralleled their effects on spore germination. Lysozyme alone only inhibited infection with A. algerae, while Lf inhibited infection by E. intestinalis and A. algerae. HNP1 significantly reduced enterocyte infection by all 3 parasite species and a combination of Lf, Lz and HNP1 caused a further reduced infection with A. algerae. These data suggest that intestinal antimicrobial peptides contribute to the defence of the intestine against infection by luminal microsporidia spores and may partially determine which parasite species infects the intestine.

Effect of x-ray energy dispersion in digital subtraction imaging at the iodine K-edge--a Monte Carlo study.

The effect of the energy dispersion of a quasi-monochromatic x-ray beam on the performance of a dual-energy x-ray imaging system is studied by means of Monte Carlo simulations using MCNPX (Monte Carlo N-Particle eXtended) version 2.6.0. In particular, the case of subtraction imaging at the iodine K-edge, suitable for angiographic imaging application, is investigated. The average energies of the two beams bracketing the iodine K-edge are set to the values of 31.2 and 35.6 keV corresponding to the ones obtained with a compact source based on a conventional x-ray tube and a mosaic crystal monochromator. The energy dispersion of the two beams is varied between 0 and 10 keV of full width at half-maximum (FWHM). The signal and signal-to-noise ratio produced in the simulated images by iodine-filled cavities (simulating patient vessels) drilled in a PMMA phantom are studied as a function of the x-ray energy dispersion. The obtained results show that, for the considered energy separation of 4.4 keV, no dramatic deterioration of the image quality is observed with increasing x-ray energy dispersion up to a FWHM of about 2.35 keV. The case of different beam energies is also investigated by means of fast simulations of the phantom absorption.

Contrast cancellation technique applied to digital x-ray imaging using silicon strip detectors.

Dual-energy mammographic imaging experimental tests have been performed using a compact dichromatic imaging system based on a conventional x-ray tube, a mosaic crystal, and a 384-strip silicon detector equipped with full-custom electronics with single photon counting capability. For simulating mammal tissue, a three-component phantom, made of Plexiglass, polyethylene, and water, has been used. Images have been collected with three different pairs of x-ray energies: 16-32 keV, 18-36 keV, and 20-40 keV. A Monte Carlo simulation of the experiment has also been carried out using the MCNP-4C transport code. The Alvarez-Macovski algorithm has been applied both to experimental and simulated data to remove the contrast between two of the phantom materials so as to enhance the visibility of the third one.

Inhibition of allospecific response in pancreatic islet transplantation: the glycan approach.

UNLABELLED: Host resistance has precluded clinical islet transplantation from becoming a consistent therapy for type I diabetic patients, mainly due to both specific and nonspecific processes. O-glycosylated proteins have a primary role in immunologic synapses. Therefore, we investigated the effects of a putative immunomodulatory effect of the cleavage of these molecules on islet allotransplantation. METHODS: Murine islets were treated with O-sialoglycoprotein endopeptidase. Three endpoints were studied: (1) proliferation in allogeneic mixed islet mononuclear cell reactions using treated and control irradiated islets as stimulator cells of mononuclear cells; (2) expression of IA-d on monocytes using 48-hour transplants of treated versus control mouse islets into subcutaneous capsules; (3) posttransplant graft function in an in vivo model of islet allotransplantation. Treated and control islets were transplanted in diabetic mice treated daily with cyclosporine. Glycemia was monitored to determine diabetes reversion. RESULTS: The allogeneic proliferative response was maximal when allogeneic mononuclear cells were mixed with control islets; it was significantly decreased with treated islets. Mean proliferative inhibition rate of treated vs. control was 62%. IA-d expression on monocytes was maximal in control islets. Reversion was significantly different for treated versus control islets with its duration varied from 3 to 7 days. CONCLUSION: These results suggest that treatment of islets with O-sialoglycoprotein endopeptidase may modulate allogeneic immunologic reactions.

Clinical and molecular analysis of three Mexican families with Pendred's syndrome.

BACKGROUND: The autosomal recessive Pendred's syndrome is defined by congenital sensorineural deafness, goiter, and impaired iodide organification. It is caused by mutations in the Pendred's syndrome (PDS) gene that encodes pendrin, a chloride/iodide transporter expressed in the thyroid, the inner ear, and the kidney. OBJECTIVE: To perform a detailed clinical and molecular analysis of patients with Pendred's syndrome from four patients from three unrelated Mexican families. METHODS: Thyroid function tests, perchlorate test, thyroid scintigraphy, audiometry, computer tomography and magnetic resonance imaging were performed in all affected individuals. Haplotype analyses were performed using microsatellite markers flanking the PDS locus, and the PDS gene was submitted to direct sequence analysis. RESULTS: All patients presented with sensorineural deafness, Mondini malformations of the cochlea, an enlarged vestibular aqueduct, goiter, and a positive perchlorate test. Two patients were hypothyroid, two individuals were euthyroid. Sequence analysis revealed a complex homozygous deletion/insertion mutation at the end of exon 4 in the index patient of family 1 resulting in a premature stop codon at position 138. In family 2, the affected individuals were compound heterozygous for a splice acceptor mutation (IVS2 -1G>A) and a 1231G>C transversion substituting alanine 411 by proline (A411P). In family 3, the index patient was found to be homozygous for a transversion 412G>T in exon 4 replacing valine 138 by phenylalanine (V138F). CONCLUSIONS: All patients included in this study presented with the classic Pendred syndrome triad and molecular analysis revealed pendrin mutations as the underlying cause. The identification of three novel mutations, one of them of complex structure, expands the spectrum of mutations in the PDS gene and emphasizes that they display marked allelic heterogeneity.

Venous endothelial function in postmenopausal women who are receiving long-term estrogen and progestagen therapy.

OBJECTIVE: To test venous endothelial function during long-term hormone replacement therapy (HRT) and after treatment withdrawal. DESIGN: Measurement of dorsal hand-vein diameter by venous occlusion plethysmography during infusion of norepinephrine, bradykinin, NG-monomethyl L-arginine, and sodium nitroprusside. SETTING: Plethysmography and menopause units, University Hospital Marqués de Valdecilla, Santander, Spain. PATIENT(S): Twenty postmenopausal women, of whom 10 were assigned to receive no hormone replacement therapy (HRT) for 6 months after plethysmography (group A) and 10 were assigned to receive HRT for 6 months (group B). After 6 months, HRT was administered to group A and withdrawn from group B for another 6 months. INTERVENTION(S): Plethysmography at baseline and at 6 and 12 months. MAIN OUTCOME MEASURE(S): Dorsal hand-vein diameter measured by venous occlusion plethysmography during infusion of norepinephrine, bradykinin, NG-monomethyl L-arginine, or sodium nitroprusside. RESULT(S): At 6 months, the maximum dilation obtained with bradykinin was 48.8 +/- 7.58% in group A and 76.7 +/- 12.9% in group B. At 12 months, maximum bradykinin dilation increased to 74.3 +/- 14.2% in group A and decreased to 54.0 +/- 15.9% in group B. CONCLUSION(S): Long-term HRT with estrogen plus progestin improves endothelium-dependent vasodilation, but this effect is lost in a relatively short time. Endothelial function in dorsal hand veins is an easy-to-use plethysmography model that can be used in serial studies.

Blunt traumatic injuries to the colon and rectum.

BACKGROUND: Experience in the treatment of patients with blunt colonic injuries is based on isolated case reports, and it is unclear whether the principles that guide the management of penetrating colonic injuries should be applied to these patients. Reviews of patients with these injuries suggest that such injuries present unique problems for diagnosis and treatment and are accompanied by excessive morbidity and mortality. STUDY DESIGN: A 42-month retrospective case series was analyzed. RESULTS: Data from 27 patients were analyzed, accounting for 8.5 percent of all colon and rectal injuries and for 0.5 percent of total blunt trauma admissions. Automobile crashes were the cause of injuries in 20 patients (74 percent). The mean Injury Severity Score was 28. All but 2 patients were operated on within 3 hours after admission. No significant difference was found in the morbidity and mortality rates based on the operation performed to manage the colonic injury. Indications for early exploration included a positive diagnostic peritoneal lavage in 23 patients, abnormal radiologic findings in 2, and positive clinical abdominal findings in the remaining 2 patients. CONCLUSIONS: Blunt colonic and rectal injuries are uncommon and pose problems for diagnosis and treatment. Associated injuries are common, and steering wheel compression of the upper abdomen as well as lap belts seem to predispose to colonic injuries. Initial diagnosis is made at the time of operation, and a thorough exploration of the abdominal cavity is important to diagnose associated injuries. Treatment must be individualized; however, based on our observations, the creation of ostomies is not mandatory for the treatment of these injuries.

Venous endothelial function in postmenopausal women after six months of tibolone therapy.

STUDY OBJECTIVE: To test venous endothelial function in long-term climateric therapy with tibolone. DESIGN: Measurement of dorsal hand-vein diameter by venous occlusion plethysmography during infusion of norepinephrine (NE), bradykinin (BK), NG-monomethyl L-arginine (L-NMMA) and sodium nitroprusside (SNP). SETTING: Plethysmography and Menopause Units. University Hospital Valdecilla. Santander. Spain. PATIENTS: Eleven postmenopausal women having continuous treatment with oral tibolone (2.5 mg/day) for 6 months. INTERVENTIONS: Three plethysmography studies were made: at baseline, and at three and six months of treatment. MAIN OUTCOME MEASURES: Dorsal hand-vein diameter measured by venous occlusion plethysmography during infusion of NE, BK, L-NMMA and SNP. RESULTS: (a) Baseline study: maximum dilation with BK was 54.2+/-10.2%. (b) Three-month study: BK dilation of 71.5+/-11.9%, with a significant increase of 17.3% (P=0.019) compared with baseline. (c) Six-month study: BK dilation of 77.5+/-11.9%, with a significant increase 23.3% (P=0.002) compared with baseline. Maximal vasodilation was reached with SNP in the three studies and L-NMMA infusion has a similar vasoconstrictor response in the three studies. CONCLUSIONS: Long-term climateric therapy with tibolone improves vein endothelium-dependent vasodilation suggesting a positive impact of this drug on endothelial function.

Cavernous hemangioma of the liver. Diagnostic value of 99mTc-labeled red cell scintigraphy: results in 28 patients.

Cavernous hemangioma is the most common benign tumor of the liver, the organ in which these lesions are most often present. We report on 28 patients who underwent 99mTc-labeled red cell scintigraphy after ultrasound or computerized tomography images suggesting the existence of one or more hepatic angiomas. In 16 patients (57.1%), an accumulation of red blood cells was considered to indicate the existence of hemangiomas. On the basis of subsequent clinical follow-up, ultrasound studies, and in one case laparotomy, all were eventually confirmed to be hemangiomas. The specificity as 100%. In the remaining 12 patients (42.9%), red cell uptake was not observed and the findings were considered negative; in this group, there were 10 true negatives and 2 false negatives in which scintigraphy failed to detect the existing angiomas due to their small size and deep location. The sensitivity was 88.8%. On the basis of the results, it is concluded that labeled red cell scintigraphy is a highly sensitive and specific method for the diagnosis of cavernous hemangioma of the liver. It should be considered the method of choice when this lesion is suspected, thus avoiding the use of more invasive diagnostic procedures such as laparoscopy which, in our study proved to be unnecessary.

[Chronic schizophrenia: validity of the study of regional cerebral blood flow through cerebral SPECT]. / Esquizofrenia crónica: validez del estudio de flujo sanguíneo cerebral regional mediante SPECT cerebral.

OBJECTIVE: To check the validity of the diagnostic test in schizophrenia. MATERIAL AND METHODS: The cerebral blood flow (CBF) characteristics were assessed by means of single photon emission tomography (SPECT) in 24 patients with schizophrenia and 20 normal control subjects. Analysis of sensitivity, specificity and the Youden rate was made of certain RCBF patterns chosen in terms of the cerebral regions between which the greatest differences were observed according to the diagnosis, schizophrenia vs control. RESULTS: Schizophrenia vs control: sensitivity = 58.33%; specificity = 95%; positive predictive value = 93.33% and overall efficiency = 53.33%. CONCLUSIONS: Cerebral SPECT is valid in the discrimination between patients diagnosed with schizophrenia and control subjects, taking the diagnostic judgement of the psychiatrist as the gold standard, and the RCBF pattern that displays the best coefficient is hypoperfusion, in one or several of the regions: right frontal/left frontal/right parietal/thalamus: sensitivity = 58.33%; specificity = 95%; positive predictive value = 93.33% and overall efficiency = 53.33%.

[Neurological sciences based on evidence]. / Ciencias neurológicas basadas en la evidencia.

OBJECTIVE: An exhaustive search of reported metanalysis from any medical speciality is described. MATERIAL AND METHODS: Search of papers included in MEDLINE or EMBASE between 1973-1998. A descriptive analysis of the reported papers (frequency tables and graphics) is described, including differences of mean of reported metanalysis papers by medical speciality and year. RESULTS: 1,514 papers were selected and classified. Between 1977-1987 overall mean of reported studies of neurologic metanalysis (1.20 +/- 1.10) was significatively inferior to the 1988-1998 (11.20 +/- 7.85) (p < 0.001). Global number of neurologic metanalysis was positively correlated (p < 0.05) with the number of studies about fundamentals and methodology during the study period. CONCLUSIONS: A progressive increase in the number of reported neurologic metanalysis since 1977 can be demonstrated. Diffusion of knowledge about fundamentals and methodology of metanalysis seems to have drawn and increase in performing and reporting this kind of analysis.

[Secondary encephalopathy due to exposure to organic solvents: psychopathological, neuropsychological and neuroimaging findings]. / Encefalopatía secundaria a solventes orgánicos: hallazgos psicopatológicos, neuropsicológicos y en neuroimagen.

Chronic exposure to organic solvents may cause permanent cognitive impairment. The nonspecify of neurological signs as the abnormalities of neurophysiological tests and morphological neuroimaging techniques have oblige the use of clinic neuropsychology in the monitorization of the neurotoxicity cause by these substances. The new modern functional neuroimaging techniques can contribute to the diagnosis of brain lesions caused by the exposure to organic solvents. We report a case that clearly supports this hypothesis as we emphasize the correlation found between clinical symptoms and the deficits obtained after the study of cerebral blood flow with single photon emission computed tomography (SPECT).

[Contribution of hepatic scintigraphy with Tc99m blood cells to the imaging diagnosis of cavernous hemangioma. Results in 48 patients]. / Contribución de la gammagrafía hepática con hematíes Tc99m al diagnóstico por imagen del hemangioma cavernoso. Resultados en 48 pacientes.

Cavernous hemangiomas are the most common benign tumours of the liver, being the liver the most frequent organ affected by this lesions. We report 48 patients who underwent 99mTc-red blood cell (RBC) scintigraphy, after ultrasound or tomographic appearance of cavernous hemangioma. Scintigraphy findings in 29 of 48 patients (60.4%) were typical of cavernous hemangioma, hemangioma-positives, after scintigraphy (all true-positives). On clinical, ultrasound and in one case after surgery (exploratory laparotomy) the follow up was positive for hemangioma. Specificity of 100%. In the remaining 19 patients (39.6%) where hemangioma-negative lesions, 17 of 19 where true negatives and the remaining 2 where angiomas false-negatives, both of them were small lesions. The sensitivity for hemangiomas was 89.4%. To conclude with we would like to enhance the high specificity and sensitivity of 99mTc-red blood cell scintigraphy on the diagnosis of cavernous hepatic hemangioma (CHH). We highlight the utility of this specific imaging technique in the final diagnosis of CHH not requiring other invasive diagnosis tests, such as laparoscopy that in our study proved to be unnecessary.

[Why evidence-based medicine? 20 years of meta-analysis]. / Por qué la medicina basada en la evidencia? 20 años de metaanálisis.

BACKGROUND: Meta-analysis, described within evidence-based medicine, has become a frequent issue in recent medical literature. An exhaustive search of reported meta-analysis from any medical specialty is described. MATERIAL AND METHODS: Search of papers included in Medline or Embase between 1973-1998. A study of intra and inter-reviewers liability about selection and classification have been performed. A descriptive analysis of the reported papers (frequency tables and graphics) is described, including differences of mean of reported meta-analysis papers by medical specialty and year. RESULTS: 1,518 papers were selected and classified. Most frequently found (45.91%) were: methodology (15.7%), psychiatry (11.79%), cardiology (10.01%) and oncology (8.36%). Inter personal agreement was 0.93 in selecting papers and 0.72 in classifying them. Between 1977-1987 overall mean of reported studies of meta-analysis (1.67 + 4.10) was significatively inferior to the 1988-1998 (49.54 + 56.55) (p < 0.001). Global number of meta-analysis was positively correlated (p < 0.05) with the number of studies about fundamentals and methodology during the study period. CONCLUSIONS: The method used to identify meta-analysis reports can be considered to be adequate; however, the agreement in classifying them in medical specialties was inferior. A progressive increase in the number of reported meta-analysis since 1977 can be demonstrated. Specialties with a greater number of meta-analysis published in the literature were: psychiatry, oncology and cardiology. Diffusion of knowledge about fundamentals and methodology of meta-analysis seems to have drawn and increase in performing and reporting this kind of analysis.