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Biomedical subjects

M E Morales

Publications and source records attributed to M E Morales.

12 recordsLinked to original sources
PubMed2006

Chemical characterization with XPS of the surface of polymer microparticles loaded with morphine.

Hydrophilic matrices are a potentially useful option for the development of oral controlled-release formulations. The porous surface of these particles makes it possible to control or modify release of the active principle after administration. As a result, such formulations can be used in liquid controlled-release pharmaceutical formulations. We investigated a method of spontaneous drug encapsulation to prepare ethylcellulose polymer microparticles (since the polymer is synthetic rather than natural the final suspension is called pseudolatex) filled with morphine hydrochloride. Morphine is incorporated to water during the synthesis process and thus it is microencapsulated inside the micelles that give rise to the final microparticles. X-ray photoelectron spectroscopy (XPS), a technique that can identify elements in a sample without destroying it, was used for the chemical analysis of the surface of these microspheres. The results demonstrated the complete absence of morphine from the microsphere surface, which was taken as evidence that the drug had been completely encapsulated.

Analgesics, Opioid↗
PubMed2005

Could the homologous sequence of anti-inflammatory pentapeptide (MLIF) produced by Entamoeba histolytica in the N protein of rabies virus affect the inflammatory process?

Amebiasis and rabies are public health problems, and they have in common a poor inflammatory effect in the target organs that they affect. In the GenBank, it was found that the anti-inflammatory peptide monocyte locomotion inhibitory factor (MLIF) produced by Entamoeba histolytica homologates 80%, with a fragment of the N protein of the rabies virus. We speculated if the N protein could contribute to the scant inflammatory reaction produced by rabies virus in central nervous system. The N protein was obtained and studied in vitro and in vivo. The N protein, as MLIF, inhibited the respiratory burst in human mononuclear phagocytes (43%, p<0.05), but in contrast to MLIF, it increased chemotaxis and it did not significantly inhibit delayed hypersensitivity skin reaction to 1-chloro-2-4-dinitrobenzene in guinea pigs. Therefore, the full peptide sequence has to be present or it has to be cleaved-free from the large recombinant N protein molecule (55 kDa) to become active.

Animals↗
PubMed2005

An experimental investigation of the stability of ethylcellulose latex: correlation between zeta potential and sedimentation.

This paper aims at explaining the experimental observations of the stability and redispersibility of an aqueous ethylcellulose latex through the electrokinetic characterization of the particles. The surface charge and the electrical double layer thickness play an essential role in the stability of the system, hence the need for a full characterization of the polymeric particles. The effect of both pH and ionic strength of the dispersion medium were investigated. It was found that at acid pH values the latex displays "delayed" or "hindered" sedimentation: in such conditions, the electrophoretic mobility and zeta potential are rather low, indicating a small electrokinetic charge on the particles. At alkaline pH, when the dissociation of ionizable surface groups must be complete, the zeta potential is high and negative. The electrostatic repulsion between polymer particles is responsible for the low sedimentation volume and poor redispersibility of the latex. The effect of NaCl and CaCl(2) concentration on both the zeta potential and stability of the latexes was also investigated: it was found that CaCl(2) has the greatest influence, yielding flocculated, easily re-dispersible systems when its concentration in the dispersion medium is high enough. There qualitative observations were ascertained by means of calculations of the potential energy of interaction between particles. In the case of NaCl solutions, a high and relatively wide potential energy barrier was predicted, that may prevent the particle aggregation. Above 5mM NaCl a shallow minimum in the potential energy curves must lead to the formation of aggregates. Similar results were found with CaCl(2) solutions, although in this case the secondary minima are deeper and appear at lower concentrations.

Calcium Chloride↗
PubMed2004

Comparative study of morphine diffusion from sustained release polymeric suspensions.

In recent years, great efforts have been devoted to the design of drug delivery systems. Many polymeric excipients have been studied in order to make drug release fit the desired profiles. The aim of this work was to design a morphine oral suspension, as sustained release pharmaceutical formulations. To this end, two different ethylcellulose suspensions were prepared: one with the drug incorporated during synthesis (suspension A) so that the drug was inside the polymeric microparticles. In the second group of suspensions the drug was incorporated after synthesis (suspension B), thus resulting in the drug being adsorbed on the surface. The analytical technique used, spectrophotometry, showed that suspensions A were able to spontaneously encapsulate approximately 92% of the drug, whereas suspensions B adsorbed only 15% dose on the particle surface. Moreover, the diffusion results obtained with Franz-cells showed that suspensions A offered the possibility of easy control of the release rate of the active substance. This system transfers morphine hydrocloride during 24 h in accordance with a Weibull kinetic model. This dosage form presents the clinical advantage of less frequent dosing, with increased quality of life for patients. This report documents the suitability of our ethylcellulose polymeric suspension for encapsulated morphine with a controlled release rate.

Analgesics, Opioid↗
PubMed2003

Increased perception of post-ischemic paresthesias in depressed subjects.

A psychophysical assessment of sensory activity linked to unmyelinated and myelinated primary afferents was conducted by estimating the intensity of thermal and tactile post-ischemic paresthesias in 11 nontreated depressed subjects (Zung's index > or =50) and 19 controls. Blood flow in the dominant forearm was arrested until ischemic pain tolerance was reached. Ischemic pain and post-ischemic paresthesias were numerically rated. The duration of blood flow occlusion to the time of ischemic pain tolerance was similar in both groups. Thermal (warm/cool) and tactile (tingling) paresthesias were 96% and 57% more intense in depressed than in control subjects, respectively. Zung's depression scores were positively correlated with the tingling and thermal paresthesias. Ischemic pain intensity correlated positively with thermal paresthesias. These findings suggest that depression is associated with enhanced sensory paresthesias that are known to be predominately linked to unmyelinated afferent activity.

Adult↗
PubMed1999

Toxicokinetics and oral bioavailability of fumonisin B1.

The kinetics of fumonisin B1 (FB1) after single doses of 10 mg FB1/kg (po) or 2 mg FB1/kg (i.v.) were studied in male Wistar rats. Serial blood samples were obtained after p.o and i.v. administration. Liver and kidney tissue samples were also obtained after p.o administration. Plasma, liver and kidney concentrations of FB1 were determined by a reversed-phase high-performance liquid chromatographic assay using precolumn 0-phthaldialdehyde derivatisation with fluorescence detection. The FB1 plasma profile could be adequately described by a 2-compartment open model. For FB1, the elimination half-life from plasma was 1.03 h after i.v. and 3.15 h after p.o administration. The apparent volume of distribution and volume of distribution at steady state for FB1 were 0.11 and 0.072 L, respectively, after i.v. administration. The total plasma clearance of FB1 was the same for both the p.o and i.v. routes, 0.072 L/h. After the single p.o dose, FB1 was rapidly absorbed with a Tmax of 1.02 h. The maximum plasma concentration of FB1 was 0.18 microgram/mL. The p.o bioavailability of FB1 was 3.5%. The tissue concentration time data for FB1 fit a 1-compartment open model. Considerable concentrations of FB1 were found in the liver and kidney tissues. The elimination half-lives for FB1 were longer for liver (4.07 h) and kidney (7.07 h) than for plasma (3.15 h). Tissue accumulation of FB1 was evidenced by the tissue/plasma area under the concentration-time curve (AUC) ratios; the AUCtissue/AUCplasma for FB1 was 2.03 in liver and 29.89 in kidney.

Administration, Oral↗
PubMedDate not supplied

In pursuit of excellence: quality assurance, documentation, and peer review by home birth CNMs.

The unique characteristics of home birth practice for certified nurse-midwives (CNMs) are applied to a quality assurance program. This article explores the mUltiple purposes, benefits, and elements of documentation as they specifically apply to home birth. The steps of documentation for a home birth practice are outlined and the three current models to consider in setting up positive peer review programs in which CNMs can succeed and learn are presented. Recommendations are made for 1) a more positive emphasis on the purposes of documentation and collection of statistics, 2) networking to close the gaps of isolation and task duplication for home birth CNMs, 3) ongoing development of models for positive peer review to facilitate participation in the mandate of the American College of Nurse-Midwives, and 4) identification of clinical indicators for quality assurance specific to home birth practice by CNMs.

Female↗
PubMedDate not supplied

[Stability of an oral liquid morphine formulation for pediatric use].

OBJECTIVE: The aim of this study the determination of the stability of an oral morphine hydrochloride solutions. METHOD: Determinations of a concentrated morphine solution of 4 mg/ml and the impact of two temperatures, 4 degrees C (refrigerator) and 25 degrees C (room) was analyzed via spectrophotometric measurements. RESULTS: Findings showed the high stability of the solutions at 4 degrees C, since no significant degradation was observed during the 30 days of the study, whereas at room temperature stability losses were hardly seen during the first 7 days, reaching 6.8% +/- 0.5% after 15 days. CONCLUSIONS: The tested morphine solution is stable at 4 degrees C during 30 days, but not at room temperature.

Child↗
PubMedDate not supplied

[Congenital tuberculosis. Description of a case].

Presentation is made of a case in a premature newborn, the offspring of a mother with bilateral pulmonary tuberculosis, of placental lesions suggestive of tuberculosis and acute miliary congenital tuberculosis with lesions in liver, spleen, lymph nodes and lungs due to a possible blood stream dissemination starting from the placental infection.

Female↗
PubMedDate not supplied

[Premature rupture of the membranes. Analysis of neonatal infection].

The study included 65 pregnant women with PRM and of 23 (control group) without PRM or infection. Out of the products from PRM, infection appeared in 13.2% and from the control group in 4.2% (p less than 0.001). No differences were found among frequency of infection and the various periods of latency of PRM, nor with the route from which the product was obtained. The overall mortality was 5.8% for the group studied and cero for the control group (p greater than 0.05) and was shown to be more related with prematurity than with the latent period of PRM. With these experiences, the prophylactic use of antibiotics is not justified in the newborn from mother with PRM.

Adolescent↗