KI effects on corrosion inhibition for 1018 steel in acid media using Medicago sativa.

Medicago sativa (M. sativa) extract is a safe and eco-friendly corrosion inhibitor of 1018 steel in acid media. The inhibitor reached a maximum efficiency of 85% by using 500 ppm. In this work, we study the use of KI as an add-on to increase the inhibition efficiency of M. sativa, as well as making the natural inhibitor competitive with the commercial ones. We evaluated the effect of halide ions through the variation of different concentrations of KI and its synergy with the extract of M. sativa as a corrosion inhibitor of carbon steel in 0.5 M sulfuric acid and at different temperatures. The results were obtained through electrochemical techniques such as electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) curves, and weight loss gravimetric technique. It was found that halide ions increase the inhibition efficiency of M. sativa from 85 to 95% when 5 mM concentration of KI was used. The efficiency of the inhibition increases proportionally with the immersion time but reduces when the temperature increases. The addition of iodide ions (I-) revealed that it exerts a synergistic effect on the inhibition of corrosion with the extract of M. sativa. However, when studying the metal surface using a scanning electron microscope, pitting corrosion was found.

Experimental and Theoretical Studies of α-Linolenic Acid as Green Corrosion Inhibitor for Carbon Steel in 0.5 M Sulfuric Acid.

A component of Salvia hispanica, α-linolenic acid, has been evaluated as a green corrosion inhibitor for 1018 carbon steel in 0.5 M sulfuric acid using weight loss tests, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) measurements. Theoretical calculations using Density Functional Theory (DFT) were used also. The results have shown that this compound is a good corrosion inhibitor, with an efficiency which increased with an increase in its concentration up to 600 ppm, but it decreased with a further increase in the concentration. α-linolenic acid formed protective corrosion products layer because it was chemically adsorbed onto the steel surface according to a Langmuir type of adsorption isotherms. Polarization curves have shown that α-linolenic acid is a good, mixed type of inhibitor with a predominant effect on the cathodic hydrogen evolution reactions. EIS measurements indicated a charge transfer-controlled corrosion process. DFT calculations indicated that α-linolenic acid was more efficient in an acidic environment than in a neutral one because has a high tendency to donate electrons and can be easily protonated. In addition to this, it had the highest EHUMO value, the best chemical reactivity, the greatest tendency to transfer electrons and a greater facility of modifying its electronic configuration in the presence of carbon steel specimens according to its chemical hardness value.

Use of a Gemini-Surfactant Synthesized from the Mango Seed Oil as a CO2-Corrosion Inhibitor for X-120 Steel.

A gemini surfactant imidazoline type, namely N-(3-(2-fatty-4,5-dihydro-1H-imidazol-1-yl) propyl) fatty amide, has been obtained from the fatty acids contained in the mango seed and used as a CO2 corrosion inhibitor for API X-120 pipeline steel. Employed techniques involved potentiodynamic polarization curves, linear polarization resistance, and electrochemical impedance spectroscopy. These tests were supported by detailed scanning electronic microscopy (SEM) and Raman spectroscopy studies. It was found that obtained gemini surfactant greatly decreases the steel corrosion rate by retarding both anodic and cathodic electrochemical reactions, with an efficiency that increases with an increase in its concentration. Gemini surfactant inhibits the corrosion of steel by the adsorption mechanism, and it is adsorbed on to the steel surface according to a Langmuir model in a chemical type of adsorption. SEM and Raman results shown the presence of the inhibitor on the steel surface.

Vertical splitting of the mandibular body as an alternative to inferior alveolar nerve lateralization.

The aim of this study was to present and evaluate a modified technique to inferior alveolar nerve lateralization (IANL) that allows the placement of longer implants in the posterior mandibular region. One hundred and forty-three consecutive patients were enrolled in this study; these patients had between 1.8 and 8mm residual crestal height above the mandibular canal. Vertical splitting of the mandibular body was performed using piezoelectric surgery followed by bone expansion and insertion of special conical implants of 10 and/or 12mm in length. Two hundred and sixty-nine osteotomies were performed and 636 implants were inserted, with a survival rate of 99% at the end of 12 months. Immediately postoperative there was an alteration of sensation in the lip/chin area in 8.5% of cases; 4.1% regained full sensation within 10-14 days, 2.6% after 8 weeks, and 0.7% had persistent paresthesia that did not affect their daily activities. Progressively increasing pain and numbness was present in 1.1%; the implants were removed 6 months postoperatively. This is a relatively simple procedure that has no limitations in clinical situations with minimal bone height. It allows for greater implant stability, and the risk of neurological disturbance is minimal.

[Maxillary sinus metastasis of renal cell carcinoma]. / Adenocarcinoma renal metastásico en seno maxilar.

Paranasal sinuses and nose metastasis are very uncommon tumors, about 50 have been reported. Renal cell carcinoma is the primary neoplasm which most frequently metastasizes in the nasosinusal region, followed by breast and lung. Symptoms are unspecific, but the epistaxis constitutes the most common sign due to the significant vascularizations of the tumor. Prognosis is poor. The survival rate fluctuates between 15-30% at 5 years. Surgery is the elective treatment.

Maximum likelihood mixture estimation to determine metal background values in estuarine and coastal sediments within the European Water Framework Directive.

Some of the recently derived European Directives, such as the Water Framework and Marine Strategy, have, as ultimate aims, to achieve concentrations of hazardous substances in the marine environment near background values. Hence, the determination of natural background levels, in marine sediments, is highly relevant. The present study proposes the use of the maximum likelihood mixture estimation (MLME) to determine regional background levels and upper threshold of metal concentration, with the Basque Country as a case study (with a data set of 575 samples, from estuarine and littoral areas, including both intertidal and subtidal sediments). The heuristic procedure is applied with unimodal data distributions (Cd, Cr, Fe and Ni) and the mixture density estimations, based upon maximum likelihood, are carried out with polypopulational data distributions (As, Cu, Mn, Hg, Pb and Zn). The upper limits of the distribution are proposed, as the limits between 'High Status' and 'Good Status' (according to the Water Framework Directive terminology). The regional upper limits were 0.45 microg g(-1) for Cd, 71 microg g(-1) for Cr, 53,542 microg g(-1) for Fe, 57 microg g(-1) for Ni, 24 microg g(-1) for As, 64 microg g(-1) for Cu, 447 microg g(-1) for Mn, 0.27 microg g(-1) for Hg, 66 microg g(-1) for Pb, and 248 microg g(-1) for Zn. The results from this study can assist further in the determination of sediment reference conditions, to assess chemical status, within the above-mentioned directives; likewise, it will be studied as a useful methodology in determining regional metal backgrounds in other European countries.

Chemoprevention of colon cancer by a glutathione conjugate of 1,4-phenylenebis(methylene)selenocyanate, a novel organoselenium compound with low toxicity.

We have consistently shown that several synthetic Organoselenium compounds are superior cancer chemopreventive agents and less toxic than selenite or certain naturally occurring selenoamino acids. 1,4-Phenylenebis(methylene)selenocyanate (p-XSC) is the lead Organoselenium compound in that it has been shown to be the most effective and the least toxic agent in several experimental cancer models. It is not known whether p-XSC or one of its metabolites is responsible for its chemopreventive efficacy. As an initial step, we synthesized one of its putative metabolites, i.e., the glutathione conjugate of p-XSC (p-XSe-SG), and determined its stability in the pH range from 2 to 8 and in the diet under normal feeding conditions. We also assessed its maximum tolerated dose and examined its chemopreventive efficacy against azoxymethane (AOM)-induced colon carcinogenesis in male F344 rats. p-XSe-SG proved to be very stable over the pH range tested. The maximum tolerated dose of p-XSe-SG determined in a 6-week subchronic toxicity study was found to be >210 ppm (>40 ppm selenium) when the compound was added to AIN-76A high-fat diet. To assess the efficacy of this agent in the postinitiation period of colon carcinogenesis, male F344 rats 6 weeks of age were fed the high-fat diet, and at beginning of weeks 7 and 8, all of the rats intended for carcinogen treatment were given AOM at a dose of 15 mg/kg body weight by s.c. injection. Two days after the carcinogen treatment, the groups of rats consuming the high-fat control diet began their respective high-fat experimental diet regimens with 0, 56, or 84 ppm p-XSe-SG (0.1, 10, and 15 ppm of selenium) supplementation. All animals continued on their respective diets for 38 weeks after the AOM-treatment and were then killed. Colon tumors were evaluated histologically using routine procedures and were also analyzed for cyclooxygenase (COX)-1 and COX-2 expression and enzymatic activities. The results indicate that p-XSeSG administered during the post-initiation stage significantly inhibited both the incidence (P < 0.05-0.01) and the multiplicity (P < 0.05-0.005) of AOM-induced colon adenocarcinomas. This agent also greatly suppressed the multiplicity (P < 0.01-0.001) of AOM-induced exophytic adenocarcinomas in a dose-dependent manner. Feeding of 56 or 84 ppm p-XSe-SG in the diet significantly suppressed total COX activity (P < 0.02 to -0.01) and COX-2 specific activity (P < 0.005-0.0005) but had minimal effect on the protein expression levels of COX-1 and COX-2. These results suggest that the newly developed synthetic Organoselenium compound, p-XSe-SG, is stable in the diet and at wide pH ranges, inhibits colon carcinogenesis when administered during the postinitiation stage, and inhibits COX activity. Compared with previous efficacy studies and considering the toxicity associated with selenium, p-XSe-SG seems to be the least toxic Organoselenium chemopreventive agent thus far tested in the experimental colon carcinogenesis. Studies are in progress to delineate whether p-XSe-SG is also effective when administered during the progression stage of colon carcinogenesis.

Chemoprevention of familial adenomatous polyposis development in the APC(min) mouse model by 1,4-phenylene bis(methylene)selenocyanate.

Epidemiological and experimental studies have suggested that dietary supplementation with selenium can inhibit the development of cancers at several organ sites. We have consistently shown that 1, 4-phenylene bis(methylene) selenocyanate (p-XSC) is a highly effective cancer chemopreventive agent against the development of chemically induced cancers in several laboratory animal species. This is the first report describing the preventive effects of p-XSC in an animal model of familial adenomatous polyposis (FAP) containing a germline mutation of the APC gene. Six-week old male (heterozygous) C57BL/6J-APC(min) or wild-type mice were fed high fat diets containing 0, 10 or 20 p.p.m. p-XSC. After 80 days, the mice were killed and their intestines were excised and evaluated for polyps. Multiple samples were also harvested from normal appearing small intestine and colon for molecular analysis. Both the mucosa and polyps from the intestine and colon were assayed for beta-catenin, cyclooxygenase (COX)-2 expression and COX isoform activities. Administration of p-XSC in the diet significantly decreased the rate of formation of small intestinal tumors (P < 0. 0001) and colon tumors (P < 0.002) in APC(min) mice. p-XSC produced a dose-dependent inhibition of tumors in both small intestine (P < 0. 0001) and colon (P < 0.035). Mice fed 20 p.p.m. p-XSC had significantly lower levels of beta-catenin expression and COX-2 activity in polyps. These observations demonstrate for the first time that the synthetic organoselenium compound p-XSC possesses antitumor activity against genetically predisposed neoplastic lesions, such as FAP. While the exact mechanism(s) for this antitumor activity of p-XSC remains to be elucidated, it appears that modulation of beta-catenin expression and COX-2 activity is associated with inhibition of intestinal polyps.

Evaluation of benzyl selenocyanate glutathione conjugate for potential chemopreventive properties in colon carcinogenesis.

Observational, clinical and experimental studies have suggested that dietary supplementation with selenium can inhibit the development of colon cancer. Since toxicity and chemopreventive efficacy of selenium compounds depend to a large extent, on the form of selenium the development of efficacious organoselenium compounds with low toxicity is being pursued in our laboratory. We have assessed the chemopreventive properties of a newly synthesized organoselenium compound, benzyl selenocyanate glutathione conjugate (BSeSG), and of benzyl selenocyanate (BSC), as a positive control, using azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF) as a measure of efficacy. Five-week-old male F344 rats were fed the control diet (modified AIN-76A) or experimental diets containing 10 or 20 ppm BSeSG (1.7 and 3.4 ppm as Se, respectively), or 10 ppm BSC (4.1 ppm as Se). One week later, all animals except those in vehicle (normal saline)-treated groups were s.c. injected with AOM (15 mg/kg of body weight, once weekly for 2 weeks). All animals were sacrificed 7 weeks after the last AOM injection, and the ACF, levels of prostaglandin E2 (PGE2), cyclooxygenase protein expression (COX-1 and -2), and glutathione S-transferase type mu (GST-mu) were determined in the colon. As expected, dietary administration of BSC suppressed ACF development by about 37%. In rats administered 10 or 20 ppm BSeSG, the frequencies of AOM-induced colonic ACF were significantly decreased compared to those of rats given AOM and control diet by about 41% (P<0.01) and 61% (P<0.001), respectively. Administration of BSeSG inhibited PGE2 production (81-88% inhibition) via COX-2 synthesis in the colonic mucosa (18-60% inhibition). Also, BSeSG increased GST-mu protein activity in colonic mucosa (30-32% increase). These data suggest that a newly synthesized organoselenium compound, BSeSG might be a promising chemopreventive agent against colon carcinogenesis.

Neurosurgery and the Internet: a critical analysis and a review of available resources.

Thanks to the development of computers and telecommunication, the concept of communication is undergoing radical changes. Scientific collaboration among medical professionals has evolved rapidly in the last few years toward the use of Internet, a new tool which will change the world of health. It is impossible to predict at present where this new type of scientific collaboration will lead us, but what is certain is that in the next decade, the so-called electronic communities will be created and will develop at an extraordinary rate. The increase in the capacity of image processing in computers and in the rate of transmission of data over the net will make possible applications such as the remote medical visit, video conferences, surgical simulation or even remote virtual surgery. However, while some medical professionals are dreaming of this type of electronic communication in the future, others are using it right now, taking advantage of all of its benefits. In fact, electronic communities are already a reality, being accessible today, and not a future goal. Being inside or outside these communities will make the difference between health professionals. It is well worth therefore being in contact with these new fields so as not to miss the boat of technological development. We present a comprehensive listing of neurosurgical resources available on the Internet, and some ideas on the present and future applications of the Internet in the world of Health Care.

Adolescent student's compliance with testicular self examination

To determine what adolescents students know or feel about testicular cancer, (TC) and the testicular self examination, (TSE), technique, 127 males students (mean age 16.14 years) were given a 21 item questionnaire. The role of the primary physician and the role of written and visual educational material were assessed for effectiveness in increasing the regular performance of monthly testicular self examination by male students at a Health Education Course at Cervantes Public School at Bayamón, P.R. Out of 127 male student, only 2.4, (n = 3), initially knew about the symptoms of TC. Analysis of the attitude and knowledge questions revealed that respondents were not sure about general concepts in TC and, were not sure that this cancer could be self diagnosed. This study pretends to assess the effects of modeling and guiding practice as components within a comprehensive testicular self examination education program for adolescents male students. Three groups were studied from 10th, 11th, and 12th, grade. The variables investigated were knowledge of testicular cancer, attitudes toward testicular cancer, and frequency of self reported testicular self examination. The participants then received written material plus a physician's lecture on TC and TSE. Upon follow up, 87.5, (n = 113) of the students reported performing monthly TSE, (P < 0.001), a statistically significant increase in performance. Although 20.3 (n = 26) reported having a physical examination by a physician within the previous 3 months, less than 4.7, (n = 6) reported being taught TSE by a physician. Physicians need to educate males about testicular cancer and its early detection

Adolescent student's compliance with testicular self examination.

To determine what adolescents students know or feel about testicular cancer, (TC) and the testicular self examination, (TSE), technique, 127 males students (mean age 16.14 years) were given a 21 item questionnaire. The role of the primary physician and the role of written and visual educational material were assessed for effectiveness in increasing the regular performance of monthly testicular self examination by male students at a Health Education Course at Cervantes Public School at Bayamón, P.R. Out of 127 male student, only 2.4%, (n = 3), initially knew about the symptoms of TC. Analysis of the attitude and knowledge questions revealed that respondents were not sure about general concepts in TC and, were not sure that this cancer could be self diagnosed. This study pretends to assess the effects of modeling and guiding practice as components within a comprehensive testicular self examination education program for adolescents male students. Three groups were studied from 10th, 11th, and 12th, grade. The variables investigated were knowledge of testicular cancer, attitudes toward testicular cancer, and frequency of self reported testicular self examination. The participants then received written material plus a physician's lecture on TC and TSE. Upon follow up, 87.5%, (n = 113) of the students reported performing monthly TSE, (P < 0.001), a statistically significant increase in performance. Although 20.3% (n = 26) reported having a physical examination by a physician within the previous 3 months, less than 4.7%, (n = 6) reported being taught TSE by a physician. Physicians need to educate males about testicular cancer and its early detection.

Injuries as an adverse reaction to clinically used laser devices.

Since the first use of lasers in ophthalmology in the early 1960s, applications for the medical laser have been found in many medical specialties. Despite their increasing usefulness, lasers have been reported to induce injuries. Few studies have tried to quantify the number of injuries caused by the clinical use of lasers. To address this issue, we surveyed physicians at the 5th Annual Meeting of the American Society for Laser Medicine and Surgery, May 1985. Forty-two of the 226 physicians attending the meeting responded to the questionnaire about their experience with lasers in their practice. An average of 25 laser procedures per month were performed by the responding physicians, and 61.9% of them reported at least one complication. Of the complications reported in the survey, 33 occurred within the last 12 months for an overall rate of 2.7 incidents per 1,000 procedures performed. The most common complications reported were burns and scarring; however, bowel perforation and pneumothorax were among the more serious. The mean number of reported complications varied by the length and type of training in the use of the laser, with the lowest number of complications reported by respondents who had taken a training course lasting longer than 7 days within the last year. Our findings show that both minor and life-threatening injury can be caused by the clinical use of medical lasers. Evaluation of the adverse effects of any medical technology, such as lasers, is needed to help guide recommendations for its safe use.

Human pulvinar units, spontaneous activity and sensory-motor influences.

Unit activity was recorded from the pulvinar nucleus (Pu) in human patients undergoing stereotaxic surgery. Thirty-six units (12 isolated and 12 pairs recorded with the same microelectrode) with a signal-to-noise ratio greater than 5, a stable amplitude, and a sustained discharge rate for more than 1 min, were selected for processing. The following functions were calculated with a digital computer to characterize discharge patterns: interval, autocorrelation and peristimulus time histograms for spikes, cross-correlation histograms between spikes of a pair, and autocorrelation functions and averages of the EEG. In spontaneous conditions, about half of the units fired in rhythmic bursts at the same or half the frequency of the Pu EEG. Most non-rhythmic units showed a "Poisson-like' interval histogram indicating a random firing pattern. Some non-rhythmic units revealed a periodic cross-correlation with the rhythmic Pu EEG, indicating that spikes tend to fire at a preferred phase of the rhythm. About half of the units showed phasic firing rate changes during voluntary movements. In most cells a discharge rate increase was observed. One unit also responded to passive movements of the fingers. Of the neurons tested, 2 out of 3 showed firing rate modulation during voluntary movements of the jaw as well as of the contralateral hand. The above units also increased the impulse rate after visual stimulation. Convergence of the effects of voluntary movements, and visual and auditory stimulation, was demonstrated in one unit. These results indicate the participation of the Pu in sensory-motor integrative functions.

Biological factors involved in the clinical features and surgical management of cerebellar hemangioblastomas.

Sixty-five personal cases of cerebellar hemangioblastomas plus others from the literature making a total of 539 cases are reviewed regarding their clinical, biological and surgical aspects. A variable genetic blastomatous growth potential seems to determine the individual biological behavior of these tumors. Retinal angiomatosis, family incidence, multicentric tumors in the central nervous system and in other organs, and some of the so-called recurrences, are considered within this concept.