G protein-independent stimulation of human myocardial phospholipase C by mastoparan.

1 Phosphoinositide-specific phospholipase C (PLC) is involved in the regulation of many cellular functions. In the myocardium, PLC-generated second messengers play a role in the regulation of contractile function and in the pathophysiology of myocardial hypertrophy. 2 In the present study, the effect of mastoparan, a tetradecapeptide which is capable of activating heterotrimeric G proteins by mimicking the action of an activated receptor, on membrane-bound human myocardial PLC, was investigated in a cell-free assay with exogenous phospholipids as a substrate. 3 Mastoparan stimulated human myocardial PLC approximately two fold with a half-maximal effect at approximately 2 microM and a maximal effect at 10 microM. The peptide did not alter the dependence of PLC on free calcium ions. In order to exclude non-specific effects of mastoparan due to its amphiphilic properties, different mastoparan derivatives were used as positive and negative controls. Mas17, an inactive mastoparan analogue with physical properties very similar to mastoparan, did not induce substantial PLC stimulation in human myocardial membranes. In contrast, Mas7, the most active mastoparan derivative known, caused a more pronounced PLC activation compared with the mother compound indicating that the effect was sequence-specific. Human myocardial PLC stimulation was pertussis toxin-insensitive and could not be abolished by addition of excess alpha-subunits from purified retinal transducin or by excess GDP or GDP/beta S. In order to investigate whether mastoparan stimulate PLC via pertussis toxin-insensitive alpha q, a deletion mutant of PLC beta 2 deficient of the site of interaction with alpha q-subunits was expressed in COS-1 cells. Both wild-type and mutant PLC beta 2 were similarly sensitive to stimulation by mastoparan. It is concluded that mastoparan stimulates human myocardial PLC by a mechanism distinct from heterotrimeric G proteins.

[The factors associated with a lengthy hospital stay in a third-level unit]. / Los factores asociados con la estancia hospitalaria prolongada en una unidad de tercer nivel.

A descriptive, cross-sectional and retrospective design was developed in order to assess the frequency of patients with lengthy hospital stay (LHS) and associated factors at the Hospital de Especialidades, Centro Médico Nacional Siglo XXI, IMSS, in Mexico City from January to April, 1993. Some 2,488 patients were discharged during this period and 541 were selected at random. There were 23.9% (n = 131) of patients who had LHS, with a specific mean of 7.7 days and a total mean of 18 days of hospital stay compared with 5 days for those patients who did not have LHS. The associated factors were: patient's origin, admission conditions, complications, hospital infections, category and specialty of attending physician, delay in laboratory and diagnostic imaging exams and results, delay in surgical interventions, and need of outside transportation at time of discharge. Characteristics of patients with greater probabilities of having LHS are outside origin, diagnosis of malignant tumor, complications, hospital infections, and delay in laboratory exams and in surgical interventions. Some of these characteristics can be modified in order to improve LHS and quality of medical care. Further investigations are required to individually analyze these characteristics as well as the justification for LHS and its costs.

[Dyslipidemia associated with food]. / La dislipidemia asociada con los alimentos.

The increase of the morbi-mortality due to CHD in México, particularly among the Social Security Institute (IMSS) workers led us to do research on the relative risk and the protection provided by foodstuffs usually consumed by these workers. We found significant evidence of low levels of cholesterol associated with dry alcoholic drinks, skimmed milk and yogurt as well as fresh cheeses. C-LDL was low among people that usually consume sweet alcoholic drinks and fresh cheese. High levels of TG were associated with those people consuming food products containing saturated fat (bacon, pork crackling, fatty red meat, fowl with skin) and viscera, more than three standard cups of alcoholic drinks three times a week, soft drinks and salt. Skimmed milk and yogurt and all vegetables were related to low levels of TG. Products related to high levels of C-HDL were all kinds of vegetables and beans. This study of IMSS worker eating habits could be useful to do research on the food intake of other worker populations, and could help us to design Health Education programs based on scientific knowledge.

[Evaluation and quality assurance of medical care]. / Evaluación y garantía de calidad de la atención médica.

This paper presents a model for the evaluation of the quality of health services. The purpose is to create a method which allows the identification of those aspects of health care which are below standard, register them, assign a responsible for its correction and implement an adequate follow-up.

[Evaluation of the medical care quality. Expectations of the patients and the workers of the medical units]. / Evaluación de la calidad de la atención médica. Expectativas de los pacientes y de los trabajadores de las unidades médicas.

Quality evaluation as a first step to improve health care is an essential step in the medical process. In the Mexican Social Security Institute (IMSS), this concern was first put into action in 1956, when a review of the medical records was undertaken at the La Raza hospital. The IMSS Medical Supervision Commission was formed in 1957, and in 1959 a medical auditorship was established. Until 1983 quality of care evaluation was centered on the information contained in the medical records. However, based on an extensive bibliographical review, the need to account for other aspects of medical care was then acknowledged, and attention was brought to issues such as the sufficiency and quality of the physical resources, availability and technical proficiency of human resources, supply of materials, organization of services, fulfillment of procedures according to current quality of care normativity, and optimization of results, all within a frame of humanitarian treatment of the patient. Quality of care can be viewed from three different angles: the patient's, the institution's, and the worker's standpoints. It has been customary to evaluate quality of care from the side of institutional expectations, unattending the other two viewpoints. In this study, a survey was made of 735 external patients, 853 hospitalized patients, and 1,353 workers, from 33 second and third level hospitals in both the federal District and the states, asking levels of satisfaction with the services provided. In the first group the highest percentage of dissatisfaction was related to medical information and doctor-patient relationship. In the hospitalization area the main problems were associated to food and attention by the social worker, but there were also problems in medical information, doctor-patient relationship, and patient orientation. Workers manifested dissatisfaction with wages and working-area conditions, and asked for more institutional support and better motivations.

[Spontaneous pneumothorax associated to active pulmonary tuberculosis]. / Neumotorax espontáneo asociado a tuberculósis pulmonar activa.

This paper reviewed 8 cases of spontaneous pneumothorax, associated to pulmonary tuberculosis during a period of time of two years at the A.L.M. General Hospital of Toluca, Mex. The diagnosis was confirmed by clinical picture, radiology and bacteriology studies. Six males and two females proceding of the low class; farmers all of them. Their age ranged between 18 and 35 years. Two of the patients showed cavitary lesions, five had difusse fibrosis of the lung. We analized the clinical manifestations and reviewed the pathogenic mechanisms as well the medical and surgical treatment. No deaths ocurred en this series. We concluded that the direct relation between active pulmonary tuberculosis and spontaneous pneumothorax is not clear, but their association in this serie suggested further studies to stablished this. We emphasized the importance of this complication rare in the world literature.

[Value of fetal hemoglobin in the diagnosis of neoplastic diseases]. / Valor de la hemoglobina fetal en el diagnostico de las enfermedades neoplasicas

In base of the actual interest on certain substances which measured in blood indicate the possible existence of neoplasic processes and because the elevation of fetal hemoglobin in patients with neoplasms or "pre-malignant" diseases, the authors of this paper decided investigate the levels of fetal hemoglobin in patients with neoplasic diseases, with and without treatment, comparing it with that obtained from a control group of healthy individuals or with infectious diseases, colagenopathies or bening tumours.

[Diagnosis of malignant neoplasms by studying the changes in the concentration of fetal hemoglobin, hemoglobin A2 and carbonic anhydrases B and C. An application of discriminating function]. / Diagnóstico de neoplasias malignas por medio de las alteraciones en la concentración de hemoglobina fetal, hemoglobina A2 y anhidrasas carbónicas B y C. Una aplicación de funciones discriminantes.

This publication proposes the utilization of an analytical discriminatory method in the diagnosis of malignant neoplasia. The multiple variable technique of analysis is suggested employing the quantification of the HbF, HbA2, AcB and AcC. This has already been demonstrated in a previous study which suffered from quantifiable variations important in neoplastic disease. The confidence of the procedure has been proven when applied to 198 known cases, having classified them adequately 94 per cent of the time.

Identification and characterization of G protein-regulated phospholipase C in human myocardium.

The generation of the second messengers inositol 1,4,5-trisphosphate (InsP3) and diacylglycerol (DAG) by phosphoinositide-specific phospholipases C (PLCs) is a key mechanism by which many cellular functions such as intracellular calcium handling or growth and differentiation are modulated. In the myocardium, PLC plays a role in the mediation of positive inotropic effects and is possibly involved in the pathogenesis of myocardial hypertrophy. Among the variety of PLC isozymes known, the PLC beta family is regulated by heterotrimeric G proteins. The aim of the present study was to identify and to characterize the PLC beta isoform present in human myocardium. PLC activity in human myocardial membranes was dependent on the presence of Ca2+. Interestingly, PLC was markedly stimulated by GTP gamma S, used as an activator of G proteins. This stimulation was completely abolished by GDP. However, purified alpha-subunits from retinal transducin (alpha 1), used as scavengers of free beta gamma-subunits, did not abolish this effect indicating GTP gamma S stimulation being mediated by G protein alpha-subunits. PLC activity was also stimulated by G protein beta gamma-subunits purified from bovine retina (beta gamma t). This stimulation was completely blocked by addition of purified alpha t. Reverse transcriptions and polymerase chain reactions (RT-PCR) provided evidence for PLC beta 1 mRNA being expressed in human myocardium, whereas PCR products corresponding to PLC beta 2 and PLC beta 3 mRNAs were not detected. It is concluded that PLC beta 1 mRNA is expressed in human myocardium. The functional properties of human myocardial PLC activity correspond well to the properties established for PLC beta 1, i.e. sensitivity to G protein alpha-as well as beta gamma-subunits. The presence of other as yet unidentified PLC isozymes is nevertheless possible. The identification of the PLC beta isozyme present in human myocardium and the understanding of its regulation by G protein subunits sets the stage for the investigation of possible involvement of this system in the pathophysiology of myocardial hypertrophy.

[Basis for the evaluation of health care quality at the medical units of the health sector]. / Bases para la evaluación de la calidad de la atención en las unidades médicas del sector salud.

A methodology for evaluating the quality of services rendered by the health institutions is presented. This methodology, proposed by the Basic Evaluation Group of the Health Sector, includes an operational diagnosis of the health care units, allowing the identification of service-rendering problems, this facilitating the elaboration of alternative solutions in the patient's best interests. It can be applied at all levels of the institutional hierarchy, from service and department levels to the macro dimension of health care. In order to obtain its best results, the methodology must be utilized systematically and continuously.