Influence of plasma kinetic energy during the pulsed laser deposition of borophene films on silicon (100).

Developing borophene films with good structural stability on non-metallic substrates to maximize their potential in photosensitivity, gas detection, photothermia, energy storage, and deformation detection, among others has been challenging in recent years. Herein, we succeeded in the pulsed laser deposition of multilayered borophene films on Si (100) with ß12 or χ3 bonding by tuning the mean kinetic energy in the plasma during the deposition process. Raman and X-ray photoelectron spectroscopies confirm ß12 and χ3 bonding in the films. Borophene films with ß12 bonding were obtained by tuning a high mean kinetic energy in the plasma, while borophene with χ3 bonding required a relatively low mean kinetic energy. Atomic force microscopy (AFM) micrographs revealed a granular and directional growth of the multilayered borophene films following the linear atomic terraces from the (100) silicon substrate. AFM nanofriction was used to access the borophene surfaces and to reveal the pull-off force and friction coefficient of the films where the surface oxide showed a significant contribution. To summarize, we show that it is possible to deposit multilayered borophene thin films with different bondings by tuning the mean kinetic energy during pulsed laser deposition. The characterization of the plasma during borophene deposition accompanies our findings, providing support for the changes in kinetic energy.

Recommendations of the Society of Thoracic Surgery and the Section of Cardiothoracic and Vascular Surgery of the Spanish Society of Anesthesia, Resuscitation and Pain Therapy, for patients undergoing lung surgery included in an intensified recovery program.

In recent years, multidisciplinary programs have been implemented that include different actions during the pre, intra and postoperative period, aimed at reducing perioperative stress and therefore improving the results of patients undergoing surgical interventions. Initially, these programs were developed for colorectal surgery and from there they have been extended to other surgeries. Thoracic surgery, considered highly complex, like other surgeries with a high postoperative morbidity and mortality rate, may be one of the specialties that most benefit from the implementation of these programs. This review presents the recommendations made by different specialties involved in the perioperative care of patients who require resection of a lung tumor. Meta-analyzes, systematic reviews, randomized and non-randomized controlled studies, and retrospective studies conducted in patients undergoing this type of intervention have been taken into account in preparing the recommendations presented in this guide. The GRADE scale has been used to classify the recommendations, assessing on the one hand the level of evidence published on each specific aspect and, on the other hand, the strength of the recommendation with which the authors propose its application. The recommendations considered most important for this type of surgery are those that refer to pre-habilitation, minimization of surgical aggression, excellence in the management of perioperative pain and postoperative care aimed at providing rapid postoperative rehabilitation.

Cardiac and obstetric outcomes in pregnant patients with heart disease: a retrospective cohort study.

BACKGROUND: Cardiac diseases complicate 4% of pregnancies, with a mortality rate between 0 and 15%. Early referral has shown to reduce the risk of maternal major cardiac events (MACEs). METHODS: We retrospectively analyzed a cohort of pregnant women with heart disease from two referral centers in Mexico City. We examined MACEs: maternal death, pulmonary edema, acute heart failure, endocarditis, stroke, myocardial infarction, acute aortic syndromes, arrhythmias requiring urgent treatment, and the need for an urgent intervention; preterm birth and obstetric events such as HELLP syndrome, preeclampsia, eclampsia, placental abruption, obstetric hemorrhage. We analyzed the association between each modified World Health Organization (mWHO) group and MACEs, preterm birth and obstetric outcomes between March 2014 and March 2019. RESULTS: Using the mWHO classification, 399 deliveries were included and stratified as follows: I, 162; II, 133; II-III, 21; III, 18; and IV, 52 patients. MACEs were observed in 12.5% of the cohort and were associated with mWHO II (odds ratio [OR], 3.0; 95% confidence interval [95% CI], 1.1-8.1; p = 0.027), II-III (OR, 3.3; 95% CI, 0.9-1.0; p = 0.116), III (OR, 5.3; 95% CI, 1.2-23; p = 0.026), and IV (OR, 8.2; 95% CI, 2.7-24.5; p < 0.001) after adjusting for age, desaturation, previous functional class, and gestational age at referral. An association between mWHO and frequency of preterm birth was observed. Association between mWHO and obstetric events, even when adjusted, was not observed. CONCLUSIONS: The prevalence of MACEs and preterm birth is similar to that seen worldwide; MACEs and preterm birth are associated with the severity of heart disease stratified by mWHO, but there is no association between the severity of heart disease and obstetric events.

Recommendations of the Society of Thoracic Surgery and the Section of Cardiothoracic and Vascular Surgery of the Spanish Society of Anesthesia, Resuscitation and Pain Therapy, for patients undergoing lung surgery included in an intensified recovery program. / Recomendaciones de la Sociedad Española de Cirugía Torácica y de la Sección de Cardiotorácica y Cirugía Vascular de la Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor, para los pacientes sometidos a cirugía pulmonar incluidos en un programa de recuperación intensificada.

In recent years, multidisciplinary programs have been implemented that include different actions during the pre, intra and postoperative period, aimed at reducing perioperative stress and therefore improving the results of patients undergoing surgical interventions. Initially, these programs were developed for colorectal surgery and from there they have been extended to other surgeries. Thoracic surgery, considered highly complex, like other surgeries with a high postoperative morbidity and mortality rate, may be one of the specialties that most benefit from the implementation of these programs. This review presents the recommendations made by different specialties involved in the perioperative care of patients who require resection of a lung tumor. Meta-analyses, systematic reviews, randomized and non-randomized controlled studies, and retrospective studies conducted in patients undergoing this type of intervention have been taken into account in preparing the recommendations presented in this guide. The GRADE scale has been used to classify the recommendations, assessing on the one hand the level of evidence published on each specific aspect and, on the other hand, the strength of the recommendation with which the authors propose its application. The recommendations considered most important for this type of surgery are those that refer to pre-habilitation, minimization of surgical aggression, excellence in the management of perioperative pain and postoperative care aimed at providing rapid postoperative rehabilitation.

Social Network Organization, Structure, and Patterns of Influence Within a Community of Transgender Women in Lima, Peru: Implications for Biomedical HIV Prevention.

Understanding social network structures can contribute to the introduction of new HIV prevention strategies with socially marginalized populations like transgender women (TW). We conducted 20 semi-structured interviews and four focus groups (n = 32) with TW from selected social networks in Lima, Peru between May and July, 2015. Participants described layers of social influence from diverse actors in their social networks. The majority identified a close relative as their primary social support, with whom they confided secrets but avoided issues of transgender identity, sexuality, and sex work. Participants described close circles of TW friends with whom they shared information about gender identity, body modification, and sexual partners, but avoided issues like HIV. Community leadership included political leaders (who advocated for transgender rights) as well as social leaders (who introduced TW to hormone therapy, body modification, and commercial sex). Detailed analysis of TW social networks can contribute to implementation and acceptability of new HIV prevention technologies.

Fiabilidad de dos pruebas de velocidad de marcha de diferentes fases cronometradas e iguales fases no cronometradas en personas mayores que viven en la comunidad / Reliability of two gait speed tests of different timed phases and equal non-timed phases in community-dwelling older persons

ANTECEDENTES La velocidad de la marcha es una medida rápida, económica y precisa para evaluar la capacidad funcional de las personas mayores, tanto saludables como con diferentes comorbilidades. Estudios previos han evaluado la velocidad de la marcha medida a lo largo de cursos de diferentes distancias, pero las fases no cronometradas no se miden de manera uniforme y se desconoce si esto afecta los resultados de la prueba. OBJETIVO El objetivo de este estudio fue evaluar la confiabilidad de la prueba de velocidad de marcha de diferentes fases cronometradas e iguales fases no cronometradas. MÉTODOS Estudio de confiabilidad descriptivo, con diseño observacional analítico y de corte transversal. Se incluyeron 136 personas mayores. Se realizaron pruebas de 4 y 10 metros, con 2 metros para la fase de aceleración/desaceleración de ambas. El promedio de dos intentos se obtuvo como la medida final de cada prueba. Los resultados se obtuvieron mediante el coeficiente de correlación intraclase (CCI) con un modelo de efectos fijos y el método Bland y Altman (con un intervalo de confianza del 95%). Se complementaron con los valores de error estándar de la media y del cambio mínimo detectable (CMD95). RESULTADOS Los resultados indican un excelente nivel de acuerdo entre los intentos de las pruebas de 4 y 10 metros (CCI = 0,959 y 0,976, respectivamente), así como entre el promedio de las dos pruebas (CCI = 0,867). Destaca un nivel de acuerdo ligeramente mejor entre los dos intentos de la prueba de 10 metros. Por lo tanto, el número de intentos no es capaz de afectar los resultados de la velocidad de la marcha; sin embargo, se requieren análisis adicionales para concluir lo mismo con respecto a la distancia de la prueba. La diferencia del análisis Bland Altman para el promedio de las pruebas de 4 y 10 metros fue 1,5945 m/s (intervalo de confianza 95%: 0,9759 a 2,2130 m/s), siendo demasiado grande y más alto que el valor CMD95. CONCLUSIONES El CCI fue excelente en todos los casos, pero se requiere un análisis adicional para concluir lo mismo con respecto a la distancia de la prueba. Existe un acuerdo insuficiente entre las dos pruebas para permitir que se utilicen indistintamente en poblaciones con las características de este estudio.

BACKGROUND Gait speed is a fast, low cost and accurate measurement for evaluating older persons' functional ability, both health and with comorbidities. Previous studies have evaluated gait speed measured over courses of varying distances, but the non-timed phases are not measured uniformly. It is unknown if this affects the results of the test. OBJECTIVE This study aims to evaluate the reliability of the running speed test of two different timed phases compared to the same nontimed phases. METHODS We conducted a descriptive reliability study, with an observational and cross-sectional analytical design. One hundred thirty-six older persons were included. Two gait speed tests were taken, one of 4 and 10 meters, and 2 meters for the acceleration/deceleration phase for both tests. The average of two attempts was obtained as a final measure of each test. The intraclass correlation coefficient was used to express the results (ICC) with a fixed effects model and the Bland and Altman method (confidence interval of 95%), complemented with the standard error of the mean and minimal detectable change with 95% confidence values (MDC95). RESULTS The results indicate an excellent level of agreement between the attempts of the tests of 4- and 10-m (ICC = 0.959 and 0.976, respectively), as well as between the average of the two tests (ICC = 0.867). The agreement was slightly better between the two attempts in the 10-meter test. The number of attempts does not affect the results of gait speed. Further analysis is required to conclude the same regarding the distance of the test (4 and 10 meters). The difference in the results of the Bland Altman analysis for the average of the 4 and 10-meter tests was 1.5945 m/s (95% confidence interval: 0.9759 to 2.2130 m/s), which is too wide and higher than the MDC95 value. CONCLUSIONS The ICC value was excellent in all cases, and the number of attempts does not affect the results of gait speed. However, further analysis is required to conclude the same regarding the distance of the test. There is an insufficient agreement between the two tests to allow them to be used interchangeably in populations with the characteristics of this study.

Application of the Hands-On Donkey Tool for Assessing the Welfare of Working Equids at Tuliman, Mexico.

Equids are still used for diverse chores in Mexico and are essential for the livelihoods of numerous families. Appropriate health and behavior are prerequisites for performing work without affecting welfare. This study aimed to assess the welfare of working equids in Tuliman, applying the hands-on donkey tool. This tool evaluates five dimensions (behavior, body condition score [BCS], wounds, lameness, and other health issues) and was applied to 438 working equids (horses, mules, and donkeys). The Kruskall-Wallis test was applied to investigate differences between species and sex. Donkeys were more common; they also presented more positive behaviors and less lameness (p < 0.05). No differences were found for BCS among species on a scale ranging from 1 to 5 (mean BCS for donkeys = 1.9; mules = 2; and horses = 1.8). Mares had significantly lower BCS (mean = 1.5) than stallions (p < 0.05) and geldings (mean = 1.9). Overall mules had better welfare evaluations. The tool allowed detection of welfare issues in working equids; a practical outcome would be implementing local welfare strategies according to its results.

[Evaluation of visceral adipose tissue and lipid level in premenopausal and postmenopausal women's]. / Evaluación del tejido adiposo visceral y de la concentración de lípidos en mujeres pre y posmenopáusicas.

BACKGROUND: Postmenopausal women present weight gain and intensification of obesity, especially visceral adipose tissue (VAT) increases in postmenopausal women. But it is still not clear whether abdominal fat increases during this stage independently of body weight. OBJECTIVE: compare the VAT and lipid profile between postmenopausal and premenopausal Mexican women. METHODS: A case control study in postmenopausal women matched for BMI with premenopausal women. Anthropometric and laboratory measurements as well as body composition analysis were performed. RESULTS: VAT was increased in postmenopausal women in contrast with premenopausal women (114.8 ± 39.5 vs 97.3 ± 29.0, p<0.05). Compared with premenopausal women, postmenopausal women showed higher total cholesterol (231 .6 ± 56.1 vs 206.8 ± 29.5 p <0.05), and LDL-cholesterol levels (145.9 ± 48.3 vs 121.7 ± 34.1, p < 0.05), whereas H DL-cholesterol remained unchanged. CONCLUSION: The results of the present study have demonstrated that Mexican postmenopausal women had a significant increment in visceral adipose tissue and in other metabolic risk factors, independent of the body mass index.

Effect of the structure on luminescent characteristics of SRO-based light emitting capacitors.

In this paper, we study the structural, optical and electro-optical properties of silicon rich oxide (SRO) films, with 6.2 (SRO30) and 7.3 at.% (SRO20) of silicon excess thermally annealed at different temperatures and used as an active layer in light emitting capacitors (LECs). A typical photoluminescence (PL) red-shift is observed as the silicon content and annealing temperature are increased. Nevertheless, when SRO30 films are used in LECs, a resistance switching (RS) behavior from a high current state (HCS) to a low conduction state (LCS) is observed, enhancing the intense blue electroluminescence (EL). This RS produces a long spectral blue-shift (∼227 nm) between the EL and PL band, and it is related to structural defects created by a high current flow through preferential conductive paths breaking off Si-Si bonds from very small silicon nanoparticles (Si-nps) (Eδ (Si ↑ Si ≡ Si) centers). LECs with SRO20 films do not present the RS behavior and only exhibit a slight shift between PL and EL, both in red spectra. The carrier transport in these LEC devices is analyzed as being trap assisted tunnelling and Poole-Frenkel through a quasi 'continuum' of defect traps and quantum dots for the conduction mechanism in SRO30 and SRO20 films, respectively. The results prove the feasibility of obtaining light emitting devices by using simple panel structures with Si-nps embedded in the dielectric layer.

Liver growth factor induces testicular regeneration in EDS-treated rats and increases protein levels of class B scavenger receptors.

The aim of the present work was to determine the effects of liver growth factor (LGF) on the regeneration process of rat testes after chemical castration induced by ethane dimethanesulfonate (EDS) by analyzing some of the most relevant proteins involved in cholesterol metabolism, such as hormone sensitive lipase (HSL), 3ß-hydroxysteroid dehydrogenase (3ß-HSD), scavenger receptor SR-BI, and other components of the SR family that could contribute to the recovery of steroidogenesis and spermatogenesis in the testis. Sixty male rats were randomized to nontreated (controls) and LGF-treated, EDS-treated, and EDS + LGF-treated groups. Testes were obtained on days 10 (T1), 21 (T2), and 35 (T3) after EDS treatment, embedded in paraffin, and analyzed by immunohistochemistry and Western blot. LGF improved the recovery of the seminiferous epithelia, the appearance of the mature pattern of Leydig cell interstitial distribution, and the expression of mature SR-BI. Moreover, LGF treatment resulted in partial recovery of HSL expression in Leydig cells and spermatogonia. No changes in serum testosterone were observed in control or LGF-treated rats, but in EDS-castrated animals LGF treatment induced a progressive increase in serum testosterone levels and 3ß-HSD expression. Based on the pivotal role of SR-BI in the uptake of cholesteryl esters from HDL, it is suggested that the observed effects of LGF would facilitate the provision of cholesterol for sperm cell growth and Leydig cell recovery.

Unexpected bond activations promoted by palladium nanoparticles.

Thioether-phosphines, 1 and 2, were applied for the stabilisation of palladium nanoparticles (PdNPs) synthesised by a bottom-up methodology, using [Pd2(dba)3] as an organometallic precursor. For the phenyl containing ligand 1, small (d(mean) = 1.6 nm), well-defined and dispersed nanoparticles were obtained; however, ligand 2 involving a long alkyl chain led to agglomerates. NMR and GC-MS analyses throughout the synthesis of the nanomaterials revealed partial cleavage of ligands by C-S and C-P bond activations, and XPS spectra of the isolated nanoparticles indicated the presence of both thioether-phosphines and their fragments on the metallic surface. Reactivity studies of molecular palladium systems as well as on extended palladium surfaces pointed out that cluster entities are responsible for C-heteroatom activations, triggering structure modifications of stabilisers during the synthesis of PdNPs.

[Hereditary sensory and autonomic neuropathy type II A: early neurological and skeletal findings]. / Neuropatía sensitiva autonómica hereditaria tipo IIA: manifestaciones neurológicas y esqueléticas tempranas.

The hereditary sensory and autonomic neuropathies are genetic disorders characterized by the loss of sensation including pain, tactile and temperature. Its clinical and molecular features vary widely; the symptoms may begin from birth or be noticed in the first or second decade, with different types of complications of trauma to the extremities such as ulcers, mutilations and acral amputations. They are classified into six groups from I to VI, determined by the abnormality in eleven genes leading to phenotypic variations in the age of onset and the presence or absence of dysautonomia signs. With the exception of type I, all are autosomal recessive. The type II of these neuropathies is characterized by insensitivity to pain, heat and proprioception. We describe three members of a Mexican family with WNK1 gene mutation that caused hereditary neuropathy IIA.

Stochastic model predicts evolving preferences in the Iowa gambling task.

Learning under uncertainty is a common task that people face in their daily life. This process relies on the cognitive ability to adjust behavior to environmental demands. Although the biological underpinnings of those cognitive processes have been extensively studied, there has been little work in formal models seeking to capture the fundamental dynamic of learning under uncertainty. In the present work, we aimed to understand the basic cognitive mechanisms of outcome processing involved in decisions under uncertainty and to evaluate the relevance of previous experiences in enhancing learning processes within such uncertain context. We propose a formal model that emulates the behavior of people playing a well established paradigm (Iowa Gambling Task - IGT) and compare its outcome with a behavioral experiment. We further explored whether it was possible to emulate maladaptive behavior observed in clinical samples by modifying the model parameter which controls the update of expected outcomes distributions. Results showed that the performance of the model resembles the observed participant performance as well as IGT performance by healthy subjects described in the literature. Interestingly, the model converges faster than some subjects on the decks with higher net expected outcome. Furthermore, the modified version of the model replicated the trend observed in clinical samples performing the task. We argue that the basic cognitive component underlying learning under uncertainty can be represented as a differential equation that considers the outcomes of previous decisions for guiding the agent to an adaptive strategy.

Circulating free testosterone in obese men after bariatric surgery increases in parallel with insulin sensitivity.

BACKGROUND AND AIM: Male hypogonadism has been linked to obesity and diabetes. We aimed to study the association of changes in insulin sensitivity and testosterone levels in severe obese patients submitted to bariatric surgery. SUBJECTS AND METHODS: Prospective intervention study with twenty consecutive patients who underwent bariatric surgery studied before and after significant weight loss. Serum testosterone, SHBG, fasting glucose, and insulin were measured among others. Free testosterone was calculated with the Vermeulen formula and insulin sensitivity with the homeostatic model assessment (HOMA). RESULTS: At baseline, thirteen patients had low total testosterone levels, whereas eight of these patients also had free testosterone levels below the reference range obtained from the control group. After bariatric surgery total testosterone, SHBG, and free testosterone significantly increased and achieved normal values in all evaluated patients. Insulin sensitivity improved in all of them. Multivariate linear regression showed that changes in fasting glucose (ß=-1.868, p=0.001), insulin (ß=-3.782, p=0.001), weight (ß=-0.622, p=0.002), and SHBG (ß=-0.635, p=0.022) were associated with changes in free testosterone (adjusted R2=0.936, F=26.613, p=0.001). When insulin resistance calculated by HOMA was in the model instead of insulin and glucose, it also was associated (ß=-3.488, p=0.008) with free testosterone (adjusted R2=0.821, F=11.111, p=0.005). CONCLUSIONS: Circulating tes tos terone in obese men increases after bariatric surgery in parallel with an improvement in insulin sensitivity.

Efecto de la adición de plasma seminal en el semen equino descongelado / Effect of seminal plasma addition on frozen-thawed equine semen

Antecedentes y objetivos: E l semen criopreservado ofrece beneficios adicionales no presentes en el semen refrigerado. S in embargo, varios factores afectan al éxito en la inseminación artificial con semen congelado de caballos. E l objetivo del trabajo es evaluar si la adición de plasma seminal a diferentes concentraciones, sobre espermatozoides equinos descongelados, afecta a la motilidad espermática, viabilidad y a nivel de membrana. Material y métodos: S e utilizaron diferentes razas, cuatro sementales de silla, y dos sementales de tiro. E n un primer experimento el semen descongelado se centrifugó, mientras en el segundo no se centrifugó. A continuación, se adicionó el plasma seminal al 10, 20, 30% suspendido en solución tampón fosfato y plasma seminal puro (100%). Resultados: En los caballos de silla el plasma seminal no afectó a los parámetros estudiados (p>0,05), pero se apreció un posible efecto tóxico del plasma seminal puro sobre las características espermáticas. E n las muestras con plasma seminal de los caballos de tiro, se observaron unos índices mejores en espermatozoides vivos con acrosoma intacto que en las muestras control. A simismo se obtuvo un porcentaje menor en espermatozoides reaccionados que en las muestras control, encontrando en esta categoría una diferencia significativa (p<0,05). Conclusiones: La incubación de los espermatozoides descongelados con plasma seminal puede frenar la reacción acrosómica, reflejado este hecho, en los bajos porcentajes de espermatozoides que han sufrido la verdadera reacción acrosómica (AU)

Background and objectives: S tallion sperm cryopreservation offers benefits not available in cooled semen. However various factors affect the success of artificial insemination with frozen-thawed equine semen. T his study aims to evaluate if adding different concentrations of seminal plasma on frozen-thawed equine spermatozoa affects sperm motility, viability and membrane status. Material and Methods: D ifferent breeds were used; four saddle stallions and two draft stallions. I n the first experiment thawed semen was centrifuged and in the second one it was not. Subsequent to that, the spermatozoa resuspended with 10, 20, 30% seminal plasma in phosphate buffered saline and pure seminal plasma (100%). Results: semen parameters of saddle stallions were not affected (p>0,05), but a possible toxic effect of pure seminal plasma was observed on sperm characteristics. S eminal plasma samples in draft breed got better rates in viable sperm with intact acrosome. A lower percentage was also found on spermatozoa with acrosome reaction than in control samples. T his category showed signif icant differences (p<0,05). Conclusions: Post-thawing spermatozoa incubation with seminal plasma can stop acrosome reaction, due to the low percentage of spermatozoa suffering true acrosome reaction (AU)

Anti-CD20 therapy in patients with refractory systemic lupus erythematosus: a longitudinal analysis of 52 Hispanic patients.

The objective of this study was to investigate the efficacy and safety of anti-CD20 treatment in Hispanic patients with refractory systemic lupus erythematosus and to determine whether baseline parameters predict disease flare. Fifty-two patients with systemic lupus erythematosus, 13 with active lupus nephritis, eight with thrombocytopenia, three with leukocytopenia, 25 with severe musculoskeletal involvement and three with skin involvement) refractory to conventional therapy were treated with anti-CD20 treatment (rituximab; MabThera, Roche) plus ongoing immunosuppressive treatment. Disease activity was assessed monthly using the SLEDAI validated for the Mexican population with a follow-up period of 6 months. At 6 months of follow-up, significant clinical improvements were detected, with a reduction in the global SLEDAI validated for the Mexican population score. Five of the 13 patients with lupus nephritis (38.4%) had a complete renal response and five (38.4%) had a partial response. Rituximab was also effective in patients with autoimmune thrombocytopenia, inducing a significant increase in platelet counts (p = 0.012). Nineteen of 25 patients with severe musculoskeletal involvement had remission of arthritis. Only one of the three patients with skin involvement had no lesions at 6 months. Rituximab treatment also allowed a reduction of the oral prednisone dose in the majority of patients. No baseline predictors of flare were found. Treatment was discontinued after the first infusion in two patients due to serum sickness and in another due to pulmonary infection. In conclusion, the addition of rituximab to conventional immunosuppressive therapy may be an effective strategy for lupus nephritis, autoimmune thrombocytopenia and inflammatory polyarthritis in patients with refractory systemic lupus erythematosus.

Segregation analysis in X-linked ichthyosis: paternal transmission of the affected X-chromosome.

BACKGROUND: Steroid sulphatase (STS) deficiency has been described in a diversity of ethnic populations. The phenotype of STS deficiency, X-linked ichthyosis (XLI), is a genodermatosis characterized by dark scaly skin. About 90% of patients with XLI have complete deletion of the entire STS gene and flanking sequences. The variable number tandem repeats, on either side of the STS gene, appear to play an important role in these interstitial deletions due to nonallelic homologous recombination (NAHR). It is difficult to establish if this NAHR occurs between two chromosomes, between sister chromatids or between the same chromatid. OBJECTIVES: To identify the parental origin of the affected X-chromosome in seven unrelated sporadic cases of XLI. METHODS: Amplification of the regions from DXS89 to DXS1134 (telomeric-centromeric) including the 5' and 3' ends of the STS gene was performed through polymerase chain reaction. GeneScan analysis was performed using the DXS987, DXS8051 and DXS1060 markers located on the short arm of the X-chromosome. Fluorescence in situ hybridization analysis was performed with a digoxigenin-labelled cDNA STS probe. RESULTS: STS gene deletion in patients with XLI involved the sequences DXS1139 and DXF22S1. In five families segregation analysis showed paternal transmission of the affected X-chromosome in the XLI carrier. It was not possible to determine the parental origin of the affected X-chromosome in two families. CONCLUSIONS: These data strongly suggest that STS gene deletion occurred in the male meiosis probably due to an intrachromosomal event, recombination between S232 sequences on the same DNA molecule, or during the process of DNA replication.