Hydroxyapatite extraction from fish scales of Tilapia.

Hydroxyapatite is the inorganic component of human bones. To be used for bone replacements, hydroxyapatite can be synthesized or extracted from natural components. In this work we present the hydroxyapatite extraction from fish scales of the same Orechromis family (Tilapia) but from two different species usually consumed in Mexico and in Spain. Our results indicate, for both species, that it is possible to obtain hydroxyapatite, and moreover, that this biomaterial is enriched with magnesium for the Mexican Oreochromis hunteri, and with aluminum for the Spanish Oreochromis niloticus.

Biomateriales para Regeneración de Tejido Óseo Extraídos de Desechos de Pescado / Biomaterials for Bone Tissue Regeneration Extracted from Fish Wastes

Resumen Los biomateriales para regeneración ósea comúnmente se basan en el diseño natural del hueso, el cual mezcla la dureza de un material cerámico como la hidroxiapatita con la flexibilidad de un polímero como el colágeno. Ambos materiales pueden extraerse de los desechos del pescado consumido en la dieta humana, tales como escamas, piel e incluso huesos. Esta extracción tiene la ventaja de aportar biomateriales naturales, de baja toxicidad y como añadido, que evitan la transmisión de enfermedades que se ha reportado para colágenos provenientes de animales mamíferos. En este trabajo se hace una revisión de bibliografía referente a la extracción de colágeno tipo I, precursores de hidroxiapatita y síntesis de compósitos de ambos, para proponer la recuperación de estos biomateriales como una alternativa amigable con el ambiente y útil para usos médicos.

Abstract Biomaterials for bone tissue regeneration are commonly based in the natural design of bone where the stiffness of a ceramic material as hydroxyapatite is combined with the flexibility of a polymer such as collagen. Both materials can be extracted from human consumed fish waste, such as scales, bones and skin. The recovery of these biomaterials from fish waste has the advantage of yielding natural materials of low toxicity, avoiding the possible disease transmission found for the collagen coming from mammalians. In this article, we review several reports about collagen type I and hydroxyapatite precursors extraction, and composite synthesis, from fish waste in order to propose these methods as a green alternative for biomaterials useful for medical purposes.

Desencadenantes de síndromes coronarios agudos. Relaciones fisiopatológicas / Triggering of acute coronary syndromes. Pathophysiologic relationships

In this review, the relationship of external triggers with the development of acute coronary syndromes is described. Based on current evidence, the pathophysiological mechanisms that probably result in the rupture of vulnerable coronary plaques are revised and preventive measures to stop the functional and lethal consequences of its occurrence are proposed.

The gas-phase reaction between hydroxide ion and methyl formate: a theoretical analysis of the energy surface and product distribution.

The potential energy surface for the prototype solvent-free ester hydrolysis reaction: OH- +HCOOCH3 --> products has been characterized by high level ab initio calculations of MP4/6-311 + G(2df,2p)//MP2/6-31 + G(d) quality. These calculations reveal that the approach of an OH- ion leads to the formation of two distinct ion-molecule complexes: 1) the MS1 species with the hydroxide ion hydrogen bonded to the methyl group of the ester, and 2) the MS4 moiety resulting from proton abstraction of the formyl hydrogen by the hydroxide ion and formation of a three-body complex of water, methoxide ion and carbon monoxide. The first complex reacts to generate formate anion and methanol products through the well known B(AC)2 and S(N)2 mechanisms. RRKM calculations predict that these pathways will occur with a relative contribution of 85% and 15% at 298.15 K, in excellent agreement with experimentally measured values of 87% and 13%, respectively. The second complex reacts by loss of carbon monoxide to yield the water-methoxide complex through a single minimum potential surface and is the preferred pathway in the gas-phase. This water-methoxide adduct can further dissociate if the reactants have excess energy. These results provide clear evidence that the preferred pathways for ester hydrolysis in solution are dictated by solvation of the hydroxide ion.

Incorporation of a GnRH agonist, leuprolide acetate, into regimens with exogenous gonadotropins to produce ovarian stimulation and ovulation in the nonpregnant squirrel monkey.

This study was designed to measure the effects of variations in the length of pretreatment with a GnRH agonist, leuprolide acetate (LA), on subsequent follicular development and ovulation. The hypothesis was that the duration of LA suppression of pituitary function does not adversely affect ovarian response to standardized ovulation induction protocols in squirrel monkeys. The first phase determined the dose and duration of LA needed to achieve a hypogonadal state. One of two groups received daily subcutaneous injections of 50 microg of LA. The other received a single injection of 175 microg of a depot suspension of LA. Sera were assayed for estradiol (E2) and progesterone (P). E2 and P levels increased 2- to 5-fold with peak levels on days 4 and 7, respectively. Suppression of steroid levels took 10 to 15 days in the LA-treated group. Depot-LA did not effectively suppress steroid production. After suppression, females receiving daily LA received five daily injections of hMG to stimulate follicular development. E2 and P increased in these animals. These results suggest that cycling squirrel monkeys have P-secreting capacity throughout the cycle. This may explain how the squirrel monkey is able to accommodate both a short (4-5 day) luteal phase of their 9 day cycle and implantation from 5 to 7 days after ovulation. A second study compared exogenous follicle stimulating hormone (FSH) to endogenous gonadotropins released as a response to LA in ovulation induction. Steroid production and hCG-induced ovulation were assessed. LA treatment was compared to a standard ovulation induction protocol by using a randomized cross-over measures design. There were no differences in E2 and P levels in response to dosages of either LA or hMG. The ovulatory response following LA treatment was not significantly greater than that using FSH. The number of animals with unovulated, large follicles was greater on the FSH protocol (12/18) compared to the LA protocol (3/18). Thus, a single injection of a depot preparation of LA is sufficient to stimulate follicular development and ovulation when followed by an hCG injection. Based on this observation and the data on unovulated large follicles, it is suggested that the ovary responds more readily to endogenous gonadotropins released by LA than to exogenous FSH.

Cryopreservation of murine zygotes for use in testing culture environments.

Developing one-cell mouse zygotes are more sensitive to in vitro environmental conditions than are cleavage-stage embryos. However, for convenience and reproducibility, cryopreserved two-cell zygotes are routinely used for such assays. Concern over the possibility of inducing damage by exposing one-cell zygotes to cryoprotective agents and freeze-thaw procedures during syngamy led us to examine one-cell zygotes, with and without visible pronuclei, in an effort to minimize or avoid these effects and obtain the highest possible developmental rate. In vivo fertilized mouse zygotes were collected 21 to 43 h after administration of human chorionic gonadotropin (hCG). Suspensions of zygotes in 2M ethylene glycol were aspirated into 0.25-ml plastic insemination straws and slowly cooled at -0.5 degree C/min to -40 degrees C before being plunged into liquid nitrogen for storage. Zygotes were thawed, rinsed, and placed in culture. Zygotes were examined initially for damage from the freeze-thaw procedure. Daily in vitro development was recorded. In this group of zygotes, no damage was apparent immediately after thawing, and a high degree of development in vitro was observed. Thus, usefulness of a cryopreservation method for one-cell murine zygotes has been confirmed.

Effect of sperm dose on pregnancy rate from intrauterine insemination: a retrospective analysis.

Both the number of motile spermatozoa inseminated and the site of insemination have been correlated with the probability of pregnancy in patients inseminated with donor sperm cells from fertile men. Nevertheless, more data on the minimum sperm dose required to achieve a pregnancy are needed to understand this apparent relationship. We analyzed retrospectively 2280 cycles of intrauterine insemination to test the hypothesis that intrauterine insemination requires a minimum number of motile sperm cells to maximize the pregnancy rate. Our analysis of 1761 cycles of intrauterine insemination using from 200,000 to more than 200 million motile sperm cells showed no significant relationship between sperm dose and pregnancy rate.

[The P wave in systemic arterial hypertension. Comparison with the echocardiogram and apexcardiogram]. / La onda P en la hipertensión arterial sistémica. Correlación con el ecocardiograma y el apexcardiograma.

The cause of an abnormal electrocardiographic P wave (AEPW) in systemic arterial hypertension (SAH) has not been delucidated. In order to demonstrate if this sign is related to volume overload of the left atrial cavity -previously we found no correlation between pressure overload of the cavity and the presence of an AEPW- 34 patients with SAH were studied; population were divided in two groups: group A (GA, n = 13), formed by 13 cases with a P wave more than 0.10 s duration (D2 standard lead) and group B integrated by 21 cases with a P wave at 0.10 s or less duration. In each cases phonocardiographic and echocardiographic (Mode M) studies were performed and the following data were obtained: "A" index (AI), left atrial dimension (LAD) and, septal (SD) and left posterior wall dimension (LPWD); besides: Sokolow electrocardiographic index (SI) and systolic (SBP) and diastolic (DBP) blood pressure. Results are shown in the following table: (Table: see text). There were not statistical differences between groups (data of SBP and DBP not shown). Correlation between LAD and AI and duration of P wave were not statistical different (data not shown). An AEPW in SAH does not seem to be cause by a volume left atrial overload. Possible it is related to an interatrial conduction defect.

[The P-wave in systemic arterial hypertension]. / La onda P en la hipertensión arterial sistémica.

An abnormal electrocardiographic P wave (AEPW) has been interpreted as indicative of heart failure, hypertrophy or dilatation of left atrium, or diminished left ventricular compliance. In order to determine the significance of this electrocardiographic sign we studied 47 cases of systemic arterial hypertension (SAH) without heart failure or coronary obstruction. Patients were assigned at 2 groups: group A (22 cases with P wave duration greater than 0.11 seg. (LEAD D2); and group B 25 cases with P wave duration less than this. The following data were studied in all cases: left ventricular ejection fraction (LVEF), left ventricular presystolic filling fraction (LVPFF), Sokoloff electrocardiographic index (SEI), final diastolic pressure of LV (FDPLV), and systolic arterial pressure (SAP). Results were: (Table: see text). There were not statistical differences in these values between groups A and B (including the FDPLV value not shown in the table). Correlation coefficient between duration of P wave and the other parameters studied were also no significant. AEPW in SAH is not related to an specifically degree of left ventricular hypertrophy or disfunction; therefore, hypertensive heart disease should not be classified taking in account this electrocardiographic sign.

Distribution of a seminal plasma-associated protein kinase inhibitor in normal, oligozoospermic, and vasectomized men.

Human sperm-free seminal plasma contains an inhibitor, which is protein in nature, of the histone kinase present in seminal plasma. Since protein kinase inhibitors have been observed to be present in spermatozoa, the objective of the present study was to determine whether this seminal plasma-associated enzyme inhibitor originates from the sperm, or whether it is a component of accessory secretion(s) comprising the seminal plasma. Sperm-free seminal plasma from normospermic (greater than 20 X 10(6) sperm/ml), oligozoospermic (less than or equal to 20 X 10(6) sperm/ml), and vasectomized donors was obtained, and inhibitor-enriched fractions were prepared by (NH4)2SO4 fractionation and gel filtration. Contamination of the sperm-free seminal plasma by spermatozoa or spermatozoan components was negligible as assessed by light microscopy, polyacrylamide gel electrophoresis, and measurement of the activity of cyclic adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase. Specific (inhibitory units/mg protein) and total inhibitory activities were determined in each of the donors by constructing linear inhibition curves using various concentrations of inhibitor. The results were correlated with the initial sperm concentration. There was no apparent relationship between the amount of inhibitory activity present and the initial sperm concentration. The histone kinase inhibitor also did not appear to be associated with testicular or epididymal secretions since it was observed in the seminal plasma of vasectomized donors. It is concluded that this inhibitor of histone kinase originates from the accessory secretions comprising the human ejaculate.

[Corrected transposition of great arteries. Surgical results]. / Transposición corregida de las grandes arterias. Resultado quirúrgico.

Thirteen patients with congenitally corrected transposition of the great arteries underwent cardiac surgery between May 1964 and May 1984. Eleven cases underwent corrective surgery and two palliative treatment. Four cases had closure of the ventricular septal defect two had pulmonary valvotomy, two closure of atrial septal defect and three tricuspid valve replacement. Two patients developed atrioventricular dissociation, requiring pacemaker insertion. Two patients died, one in the immediate postoperative period in pulmonary edema, and another due to bacterial endocarditis 3 years after surgery. Our observations suggest that surgical treatment of corrected transposition can be achieved with acceptable risks. The long-term follow up in the survivors was excellent.

Transposicion corregida de las grandes arterias. Resultado quirurgico. / Repaired transposition of the great arteries. Surgical results

Trece pacientes portadores de transposicion corregida de las grandes arterias (TCGA) fueron tratados quirurgicamente en un periodo comprendido entre mayo de 1964 y mayo de 1984. En dos de ellos, se practico cirugia paliativa y en los demas cirugia correctiva. En cuatro casos fue cerrada la comunicacion interventricular, dos sufrieron valvulotomia pulmonar, dos cierre directo del defecto septal interatrial y tres reemplazo de la valvula tricuspide.Dos pacientes desarrollaron bloqueo atrioventricular completo en el postoperatorio.Un enfermo murio en el postoperatorio inmediato a consecuencia de un edema agudo pulmonar. Otro fallecio por endocarditis infecciosa 3 anos despues de la cirugia.Nuestros resultados sugieren que el tratamiento quirurgico de la transposicion corregida de las grandes arterias se hace con riesgo aceptable. El resultado a largo plazo es excelente

The role of surface charge and hydrophobic interaction in the activation of rat liver adenylate cyclase.

Rat liver plasma membranes were incubated either with procaine, lidocaine or tetracaine to study the binding of glucagon to receptors and the responses of adenylate cyclase to glucagon or fluoride. Procaine treatment increased the glucagon and fluoride activation of the cyclase and the stimulation was concentration-dependent; this compound seemed to act at the G/F unit level since changes in the glucagon binding were not observed and the basal activity was not modified. Tetracaine inhibited the adenylate cyclase activity in the order glucagon greater than basal greater than fluoride; it seems that tetracaine acted at the receptor unit level since it reduced the binding affinity. Tetracaine at high concentration (10 mM) also inhibited the fluoride stimulation of the Lubrol PX-solubilized enzyme; apparently the anesthetic acts on the G/F unit and this would indicate the component is still bound to the catalytic unit. The solubilized enzyme is not longer stimulated by procaine. These data suggested that the F component site of the G/F units is in some aspects different to the G component and more resistant to the detergent. The results of this work allowed a clear distinction among the different components of the glucagon-stimulated adenylate cyclase system and showed the importance of surface charge and hydrophobic interactions as regulatory mechanisms.

[Late arrhythmias in the operated interatrial communication. Analysis of sinus node function and the conduction pathways by His bundle electrocardiography]. / Arritmias tardías en la comunicación interauricular operada. Análisis de la función del nódulo sinusal y de las vías de conducción con eletrocardiografía de His.

Four hundred patients with atrial septal defect treated surgically were reviewed. Thirty five (8.7%) developed arrhytmias post-surgery which persisted for over a year. Sinus bradycardia was found in 10 patients, nodal rhythm in 21, and atrial fibrilation and flutter in 4 patients. Thirty five per cent of the patients with late arrhythmias developed related symptomatology. In 14 patients the function of the sinus node was studied with electrical stimulation of the atrium and with His registry. The interatrial conduction time, AV node and His Purkinje were analized employing various stimulation frequencies. All the cases studied had normal intra-atrial conduction; the response of the atrio-ventricular node to increasing frequencies was normal, an the intraventricular conduction remained constant. In 8 patients (52%), alterations of the sinus node were found; these consisted of prolonged post-stimulation pauses, Wenckebach's type sinoatrial block and suppression of sinus automatism employing vagal procedures or through electrical stimulation. A patient with severe bradycardia detected by dynamic electrocardiography had to be treated with a permanent pacemaker. We confirm that these arrhytmias are not produced by lesions of the internodal tracts, and that an alteration of the sinus node is frequent without a concomitant lesion of the intraventricular pathway. The lesion to the nutrient artery could be due to trauma and/or surgically induced. The response to anticholinergic drugs was good. Prolonged observation of these patients could increase the morbility of these arrythmias and raise doubts of the surgical indications in cases with moderate hemodynamic repercussion.