Inertia suppresses signatures of activity of active Brownian particles in a harmonic potential

A harmonically trapped active Brownian particle exhibits two types of positional distributions-one has a single peak and the other has a single well-that signify steady-state dynamics with low and high activity, respectively. Adding inertia to the translational motion preserves this strict classification of either single-peak or single-well densities but shifts the dividing boundary between the states in the parameter space. We characterize this shift for the dynamics in one spatial dimension using the static Fokker-Planck equation for the full joint distribution of the state space. We derive local results analytically with a perturbation method for a small rotational velocity and then extend them globally with a numerical approach.

Comparative 16S rRNA gene sequencing study of subgingival microbiota of healthy subjects and patients with periodontitis from four different countries

AIM

To investigate the differences between the subgingival microbiota of healthy subjects (HS) and periodontitis patients (PP) from four different countries through a metagenomic approach.

MATERIALS AND METHODS

Subgingival samples were obtained from subjects from four different countries. Microbial composition was analysed through high-throughput sequencing of the V3-V4 region of the 16S rRNA gene. The country of origin, diagnosis and clinical and demographic variables of the subjects were used to analyse the microbial profiles.

RESULTS

In total, 506 subgingival samples were analysed: 196 from HS and 310 from patients with periodontitis. Differences in richness, diversity and microbial composition were observed when comparing samples pertaining to different countries of origin and different subject diagnoses. Clinical variables, such as bleeding on probing, did not significantly affect the bacterial composition of the samples. A highly conserved core of microbiota associated with periodontitis was detected, while the microbiota associated with periodontally HS was much more diverse.

CONCLUSIONS

Periodontal diagnosis of the subjects was the main variable explaining the composition of the microbiota in the subgingival niche. Nevertheless, the country of origin also had a significant impact on the microbiota and is therefore an important factor to consider when describing subgingival bacterial communities.

Pre-exposure prophylaxis and its implications in Mexico: notions of men who have sex with men

Background The aim of this study was to analyse ideas regarding pre-exposure prophylaxis (PrEP) for the prevention of HIV among groups of men who have sex with men in Mexico for future implementation in health services.

METHODS

During 2015, 54 people participated in four focus groups in three Mexican cities. Issues related to challenges for uses and limitations of PrEP were explored.

RESULTS

In contrast with other qualitative studies, which emphasised problems with relationships with other people for PrEP use or access to key populations, Mexican participants focused their concerns around the public health services organisation: PrEP is too expensive and the health services have no resources, which will affect services and result in discrimination. Participants identified possible stigmatisation related to prejudices of medical providers who do not approve the decreased use of condoms. As a potential solution, participants suggested that the Mexican Government could negotiate a lower cost for PrEP and public health services could provide the medication, with periodical review of the arrangements by civil organisations.

CONCLUSION

In the current context of the new Mexican government, it is necessary to propose public politics focused on negotiating with pharmaceutical companies on the costs of the PrEP, coordinating public services with groups within civil society and strengthening policies and actions to reduce stigma and discrimination.

HIV prevalence, AIDS knowledge, and condom use among female sex workers in Santiago, Chile

This paper describes HIV seroprevalence, knowledge of HIV transmission, and condom use among female sex workers (FSW) attending five specialized sexually transmitted disease (STD) clinics in Santiago, Chile. A short questionnaire with socio-demographic, AIDS knowledge, and condom-use variables was administered to 626 FSW. HIV seroprevalence was estimated with a blood test sent to the Chilean Public Health Institute. ELISA was used to confirm HIV in suspected cases. HIV prevalence was 0%. FSW showed adequate overall knowledge of HIV, even better than reported for the Chilean general population on some items. Condom use with clients was high ("always" = 93.4%), although regular use with steady partners was low ("always" = 9.9%). The zero HIV seroprevalence and consistent condom use with clients confirms the positive impact of intervention strategies for FSW, increasing both correct knowledge of AIDS and condom use with clients and helping decrease these women's HIV/AIDS vulnerability.

The Chilean AIDS Cohort

Chile, middle-income country with 15 million people, began an expanded access program (EAP) to antiretroviral therapy (ART) in 2001. EAP provides ART, monitoring, and funding for management of associated complications in 32 points of care. A national cohort (Chilean AIDS Cohort [ChiAC]), enrolling 98% of these patients, was created for standardized treatment and impact evaluation. Information exchange is mainly through the Internet. By December 2004, the ChiAC had 4365 participants (83.3% male). At baseline, 47.5% had clinical AIDS, 26.2% were asymptomatic, 80.2% had a CD4 count <200 cells/mm and 58.2% were ART naive; in these patients, the most frequent regimen is zidovudine, lamivudine, and efavirenz. A 6-month follow-up in 1057 patients showed a global mortality of 5% (0.5% if patients were asymptomatic at baseline and 8.3% if patients had baseline AIDS). There was a similar risk of death if the baseline CD4 count was 100 to 200 cells/mm or >200 cells/mm ( approximately 1%), but this increased to 4.8% (relative risk [RR] = 5.2) and 10.7% (RR = 11.5) if the CD4 count was 51 to 100 cells/mm or <or=50 cells/mm, respectively. Discontinuation occurred in 7.7% of patients because of drug toxicity, and progression occurred in 2.9%. A successful EAP to ART with the resources of a middle-income country is possible. Early results are similar to those of industrialized countries. A national cohort allows better implementation and evaluation of the program and may be a useful model for other countries.

Prevalences, genotypes, and risk factors for HIV transmission in South America

HIV cross-sectional studies were conducted among high-risk populations in 9 countries of South America. Enzyme-linked immunosorbent assay screening and Western blot confirmatory testing were performed, and env heteroduplex mobility assay genotyping and DNA sequencing were performed on a subset of HIV-positive subjects. HIV prevalences were highest among men who have sex with men (MSM; 2.0%-27.8%) and were found to be associated with multiple partners, noninjection drug use (non-IDU), and sexually transmitted infections (STIs). By comparison, much lower prevalences were noted among female commercial sex workers (FCSWs; 0%-6.3%) and were associated mainly with a prior IDU and STI history. Env subtype B predominated among MSM throughout the region (more than 90% of strains), whereas env subtype F predominated among FCSWs in Argentina and male commercial sex workers in Uruguay (more than 50% of strains). A renewed effort in controlling STIs, especially among MSM groups, could significantly lessen the impact of the HIV epidemic in South America.

Health care costs and financial consequences of epidemiological changes in chronic diseases in Latin America: evidence from Mexico

OBJECTIVE

To determine the costs of health services and the financial consequences of changes in the epidemiological profile of chronic diseases in Latin America.

STUDY DESIGN

We conducted longitudinal analyses of costs and of the economic impact of the epidemiological transition in healthcare services for diabetes and hypertension in the Mexican health system. The study population included both the insured and uninsured populations.

METHODS

The cost-evaluation method was based on the instrumentation and consensus techniques. To estimate the epidemiological changes and financial consequences for 2004-2006, six models were constructed according to the Box-Jenkins technique, using confidence intervals of 95% and the Box-Pierce test.

FINDINGS

Costs ranged from US$613 to US$887 for diabetes, and from US$485 to US$622 for hypertension. Regarding epidemiological changes for 2004 compared with 2006, an increase is expected in both cases, although results predict a greater increase for diabetes, 10-15% in all three institutions (P<0.05). Comparing the financial consequences of health services required by insured and uninsured populations, the greater increase (17%) will be for the insured population (P<0.05). The financial requirements for both diseases will amount to 9.5% of the total budget for the uninsured population and 13.5% for the insured population.

CONCLUSIONS

If the risk factors and the different healthcare models remain as they are at present, the economic impact of expected epidemiological changes on the social security system will be particularly strong. Another relevant financial factor is the appearance of internal competition in the use and allocation of financial resources among the main providers in the health services; this factor becomes even more complicated within each provider. In effect, within each institution, hypertension and diabetes programmes must compete for resources with other programmes for chronic and infectious diseases.

Who pays more for health services in middle-income countries: lessons from Mexico

An evaluative study with a cross-sectional design was carried out on healthcare cost indicators reported by the 2000 National Health Survey in Mexico, to determine which population group had higher health costs/expenditures in relation to family income. The results suggest that in middle-income countries such as Mexico, families with lower incomes tend to pay more for healthcare services.

[Financial requirements for health services demands for diabetes and hypertension in Mexico: 2001-2003]

This paper presents the results of a prospective study aimed at identifying financial requirements to provide and finance healthcare services during the period 2001-2003, for high blood pressure and diabetes, the two main chronic diseases demanding healthcare services in Mexico. The study population was drawn from Mexico's three main healthcare institutions: The Ministry of Health (SSA); the Mexican Institute of Social Security (IMSS); and the Institute for Social Security and Services for State Workers (ISSSTE). The costing method was based on instrumentation and consensus techniques per average case management. Six Box-Jenkins probabilistic models were constructed to estimate the epidemiologic change for the period 2001-2003. Study findings suggest that if risk factors and healthcare provision models remain unchanged, the financial consequences would have a greater impact on the Ministry of Health, followed by IMSS and ISSSTE. Financial requirements for both diseases will account for nearly 2% of the total budget allocated to the uninsured, and 3.5% for the insured population. Indirect costs showed a similar trend in the three institutions, representing nearly 23% above total direct costs.

[Trends on generation and reproduction of knowledge about economic evaluation and health]

This paper identifies the trends and recent progress in the generation and reproduction of knowledge on health economic evaluation. Analysis is organized along nine public health action fields, namely: health determinants and predictors, economic value of health, healthcare demand, healthcare supply, microeconomic evaluation of healthcare, healthcare market balance, evaluation of policy instruments, general evaluation of the health system, and healthcare planning, regulation and supervision. Each action field is defined to place the reader in the proper setting and level of analysis. In addition, thematic research topics developed in each action field are proposed and discussed. The generation and reproduction of knowledge on the different action fields was based on the review of the bibliographic databases MEDLINE and LILACS for the 1992-2000 period. Results lead to the conclusion that development and application of economic evaluation of healthcare has been uneven across different countries and that there is a growing increase of applications starting in 1994, the year of initiation of healthcare reform in Latin America.

Financing indicators for health care decentralization in Latin America: information and suggestions for health planning

This article presents the results from an evaluative longitudinal study with before-after design. The main objective was to determine the effects of health care decentralization on changes in health financing. Taking into account feasibility, political and technical criteria, three Latin American countries were selected as study populations: Mexico, Nicaragua and Peru. The methodology had two main phases. In the first phase, the study referred to secondary sources of data and documents to obtain information about the following variables: type of decentralization implemented, source of finance, funds of financing, providers, final use of resources and mechanisms for resource allocation. In the second phase, the study referred to primary data collected in a survey of key personnel from the health sectors of each country. Taking into account the changes implemented in the three countries, as well as the strengths and weaknesses of each country in financing and decentralization, a rule for decision-making is proposed that attempts to identify the main financial changes implemented in each country and the basic indicators that can be used in future years to direct the planning, assessment, adjustment and correction of health financing and decentralization.

Health financing changes in the context of health care decentralization: the case of three Latin American countries

OBJECTIVE

The results of an evaluative longitudinal study, which identified the effects of health care decentralization on health financing in Mexico, Nicaragua and Peru are presented in this article.

METHODS

The methodology had two main phases. In the first, secondary sources of data and documents were analyzed with the following variables: type of decentralization implemented, source of financing, funds for financing, providers, final use of resources, mechanisms for resource allocation. In the second phase, primary data were collected by a survey of key personnel in the health sector.

RESULTS

Results of the comparative analysis are presented, showing the changes implemented in the three countries, as well as the strengths and weaknesses of each country in matters of financing and decentralization.

CONCLUSIONS

The main financing changes implemented and quantitative trends with respect to the five financing indicators are presented as a methodological tool to implement corrections and adjustments in health financing.

Endoscopic treatment of sinonasal disease in patients who have had orthognathic surgery

Certain skeletofacial patterns may be predisposed to aggravated sinonasal disease postoperatively. These may include, but are not limited to, facial skeletal asymmetries with high septal deviations and those with obstructive nasal respiration and mouth breathing that leads to skeletal growth disturbances such as vertical maxillary hyperplasia and apertognathism. These sinonasal diseases may partly be the result of osteomeatal blockage by pre-existing structures, or synechial shelves and webs blocking normal maxillary antral mucosal flow. The use of nasal antral windows placed anteriorly in the lateral nasal wall at the time of downfracture LeFort (Hosaka window) do not seem to benefit the drainage of the maxillary antrum. This is because physiological flow often bypasses this region. If patients present postoperatively with new sinonasal disease or the aggravation of pre-existing symptoms, evaluation by both endoscopically assisted intranasal and axially and coronal computed tomography (CT) is recommended. Functional endoscopic sinus surgery by the minimally invasive Messerklinger technique, combined with intranasal use of laser-assisted turbinoplasty and soft tissue lysis, have been successfully used for most of these patients. Because the anatomical positioning of the midfacial structure can potentially affect patients with a predisposition to sinonasal physiological disturbances, consideration should be given to preoperative evaluation and discussion of potential consequences.

[Analysis of participation in surveys in 5 countries: the importance for public health research]

This study compares participation rates and reasons for nonresponse in surveys conducted in five countries of Latin America and the Caribbean. The objective of the surveys was to measure the prevalence of risk behaviors affecting the transmission of human immunodeficiency virus. The surveys were based on probability samples of the population of both sexes between 15 and 49 years old, except in Mexico, where only men were included. Proportions of three components of participation were estimated: residences interviewed, interviewed residences with eligible persons, and eligible persons who completed the interview. In addition, an overall index that combined the three components was calculated. The overall response rate ranged from 35.6% in Mexico to 81.4% in Chile. The component with the greatest variability was the participation of eligible persons, which ranged from 50% in Mexico to 95% in Cuba. These values were lower than what had been expected, especially among men, and will serve to guide future surveys, since rejection rates higher than the ones expected in the protocol should be considered. The results make it possible to infer the validity of the prevalence estimates for the various observed risk behaviors. The results also establish a benchmark to calculate the sample size in future surveys and to improve research methodology.

[Efficacy indicators for the allocation of health resources]

This review proposes an analytical method for the development of efficacy indicators, that will allow the integration of diverse technical criteria in the allocation of health resources. Indicators of epidemiological, clinical, organizational and economic efficiency were the four levels of conceptual approach integrated in the analytical framework. The different elements of each level are interrelated to compose an analytical perspective that can be used to guide the mechanisms of resource allocation based on technical criteria. This perspective allows the development of new relevant public health instruments, specially designed for the allocation of resources.

[Ambulatory medical care in Mexico: the cost for users]

OBJECTIVE

To analyze the results of the National Health Survey (ENSA-II) as to the costs generated by the search and obtainment of ambulatory medical attention in various institutions of the private and public health sector.

MATERIAL AND METHODS

Information was raised from the health care cost indicators reported by the study population of the ENSA-II. The dependent variable was the direct expense for the consumer and the independent variables, the condition of being insured and the income. Variation significance levels were identified using the test by Duncan.

RESULTS

The costs at national level in US dollar were: transport $2.20, medical visit $7.90, drugs $9.60, diagnostic studies $13.6; average total cost for ambulatory attention was $22.70. Empirical finding suggest a new direct and indirect cost-for-consumer analysis for the health care users. These costs represent an important burden on the family income, which worsens when users are not insured.

CONCLUSIONS

Incorporation of the economic perspective to the analysis of public health issues should not be limited to the analysis of the health provider's expenses, particularly if the problems of equity and accessibility must be solved, which are at present characteristic of health care services in Mexico.

[Cost-effectiveness of interventions for end-stage renal disease]

OBJECTIVE

The study reports the cost-effectiveness results of end-stage renal disease (ESDR) patients in Mexico in terms of years of life gained and quality of life and the economic cost with regards to three treatment alternatives that could be considered mutually exclusive: continuous peritoneal ambulatory dialysis (CAPD), hemodialysis (HD) and renal transplant (RT).

METHOD

The economic costs were calculated by using the average cost case-management methodology and further, the probable of life expectancy and the quality of life were cross-sectionally assessed by means of the Quality Adjusted Life Years (QALY) measured by the Rosser Index.

RESULTS

The results show that economic costs in US$ of the three treatment alternatives were: CAPD $5,643.07, HD $9,631.60, and RT $3,021.63. The probability of life expectancy for CAPD and RT for the first and third year were: 86.2% and 66.9%, and 89.9% and 79.6%, respectively. The QALY scores for patients were: CAPD 0.8794, HD 0.8640, and RT 0.9783.

CONCLUSION

The intervention with the highest cost-effectiveness coefficient was the renal transplant (3,088.69), followed by the CAPD (6,416.95) and HD (11,147.68). A significant difference was found between the transplanted patients and patients undergoing dialysis. Finally, this study concluded that the RT offers the least expensive alternative and the greatest number of years of life gained as well as providing significant changes in the quality of life of ESRD patients.

[Costs of interventions for patients with chronic renal disease]

INTRODUCTION

The results of a study which identified the cost of health interventions in the management of patients with chronic renal disease are presented.

MATERIAL AND METHOD

The costing method was based on a consensus technique and the instrumentation of case management through the identification of the materials used and functions of production for the demand of each service solicited. The interventions included: peritoneal dialysis, hemodialysis, and renal transplant.

RESULTS

The cost per event in U.S. dollars was $3.71, $57.95, and $8,778.32, respectively. The annual cost of case management was: Peritoneal Dialysis $5,643.07, Hemodialysis $9,631.60 and renal transplant $3,021.67.

CONCLUSIONS

The information generated from the costs of the events differed considerably from the information that was generated by the annual cost of case management. These differences are significant for the design and evaluation of patterns for allocating resources.

[Prescriptions, access, and expenses on drugs among users of health services in Mexico]

OBJECTIVE

To analyze the medical prescription, drug access and drug expenditure by patients based on the National Health Survey in Mexico, 1994.

MATERIAL AND METHODS

A descriptive analysis of drug access and expenditure was undertaken and predictive factors for medical prescription were identified by logistic regression for 3,324 patients.

RESULTS

78% of the patients received drug prescriptions. 92% of the Social Security patients and 35% of the Ministry of Health patients received drugs free of charge (p = 0.000). The region with the highest poverty index received the least amount of drugs free of charge. Regarding drug expenditure of patients who purchased drugs, median expenditure was 40.00 pesos (12.50 USD). Private health service patients spent significantly more than public health service patients.

CONCLUSIONS

Drug access and drug expenditure are linked to socioeconomic factors and to the institutions attended by patients. The Mexican health system faces, among others, the challenge of increasing the equity of access to medical drugs.

Costs and financial consequences of the changing epidemiological profile in Mexico

This article presents an analysis of health-care costs and financial consequences of changes in the epidemiological profile in Mexico. Four tracer diseases were selected to conduct this study: two non-communicable diseases (arterial hypertension and diabetes) and two communicable ones (diarrhea and pneumonia). Costs involved in disease case-management, both in economic and planning terms, predict the internal competition for resources to finance health services for each tracer disease. In addition, the change in the number of cases expected during the study period highlights the process of internal competition and adds an element of intrinsic competition in the management of ambulatory and hospitalized cases for each disease. Study results support the conclusion that if preventive programs remain unchanged, the increasing demands for curative health care may cause great financial and organizational challenges to the health care system of middle-income countries like Mexico.

[The economic costs in the production of health services: from the cost of inputs to the cost of case management]

OBJECTIVE

To generate information on costs of health services.

MATERIAL AND METHODS

Using Kessner's criteria the tracer conditions selected were: hypertension, diabetes, diarrhea and pneumonia. Case-management definitions were established and then, -using the case-management costing method-the production functions, inputs and unit costs necessary to meet the demand for medical care per condition. Data were processed in a spreadsheet software package to estimate in-patient and out-patient case-management costs.

RESULTS

Findings from this study show that using in-patient and out-patient case-management costing it is possible to identify the relative weight of the different production functions and inputs. Using the relative frequencies, both production functions and inputs were classified in high, medium and low impact on the total case-management cost.

CONCLUSIONS

This information suggests that planning, organization and resource allocation should be guided by in-patient and out-patient service demands for each tracer conditions. In addition we suggests direct action to stimulate the obtention of economic earnings from resources utilization in the most efficient way.

[Economic assessment of the epidemiological profile change: information for health care reforms]

Taking into account the information needed to implement the reform process of the health sector, we present the results of an analysis of costs and the financial consequences of the epidemiological change of four tracer diseases in Mexico, two chronic (diabetes and hypertension) and two infectious diseases (pneumonias and diarrheas). The hospital cost-case management of diabetes expected for 1998 represents the same amount of hospital and ambulatory case management of diarrheas and pneumonias for the same year. The internal competition for resource allocations that is expected, among other factors, is one of the results that permits the argument that changes in the epidemiological profile generate relevant financial consequences in the planning and implementing of structural reforms of the health systems, particularly with regards to the patterns of resource allocation for specific health programs.

Changes in the quality of life of patients with end-stage renal disease treated with high-efficiency bicarbonate hemodialysis in Mexico

In accordance with the epidemiological changes in Mexico, the results of this study are intended to contribute to the evaluation of the end-stage renal disease (ESRD) program of the health services in Mexico. We measured the quality of life of 21 ESRD patients before and after 6 months of exposure to treatment with high-efficiency hemodialysis with bicarbonate (HEHD/bicarbonate). We cross-sectionally assessed the Quality Adjusted Life Year (QALY) index and the biochemical status of the subject pool. The QALY score for patients undergoing HEHD/bicarbonate after 6 months was significantly higher than with the previous dialysis modality (0.95 and 0.74, respectively, p = 0.02). The marked similarities of the biochemical status variables indicated there was little or no effect in the improvement of the quality of life of patients. Dialysis modality likely exerts an important influence on the quality of life of chronic dialysis patients; thus we believe HEHD/bicarbonate does offer greater benefits than hemodialysis alone. Longitudinal studies are needed to better ascertain the effect of the case mix, the treatment approach, and the characteristics of the dialysis in relation to the improvement of the quality of life of ESRD patients.

Cost of diseases in Brazil: breast cancer, enteritis, cardiac valve disease and bronchopneumonia

The results from the need to develop methodologies for performing cost analysis in developing countries, principally in the region of Latin America, were studied. It, furthermore, serves to generate knowledge from an economic evaluation in order to support decision-making related to the organization of health systems, particularly in the efficient use of resources which are allocated for the provision of medical services. Two chronic diseases (breast cancer and cardiac valve disease) and two infections (enteritis and bronchopneumonia) were selected for the study. The results recommend the use of a valid methodology for economic cost analysis of any disease to be studied and the use of this information in the decision-making process.

[An approach to the study of health services costs in Mexico]

OBJECTIVE

To approach the cost analysis of the health services for eight tracer conditions, in three institutions of the public sector and in five of the private sector.

MATERIAL AND METHODS

First, production functions and inputs required for standard case-management of each tracer condition were identified. Subsequently, tracer case-management was adjusted for each institution through expert consensus techniques. Once the type and amount of inputs necessary to produce tracer-specific health care services were identified, case-management costs were estimated. Tracer conditions were: hypertension, diabetes, diarrheas, pneumonia, appendicectomy, labor and delivery care, routine ambulatory medical care and vaccines.

RESULTS

Results indicate significant differences with regards to the production of medical services between both sectors and within each one.

CONCLUSIONS

The comparative analysis in the cost per case-management for each tracer presents differences that could be explained due to the quantitative and qualitative processes that characterized each institution in the combination of inputs to produce services and for the different costs of the inputs for each of the sectors analyzed, resulting in lower costs in the public sector and higher costs in the private sector, particularly for private health insurance.

[Advances and challenges in health economics]

Health economics is a specialized field of economic science that applies the economic perspective to the fields of health, the medical-industrial complex and health services. A brief review of the evolution of this speciality by subject, as well as the level achieved assessed in terms of generation, diffusion, reproduction and application of its specialized knowledge, is presented.

[Teaching of health economics in Mexico: 5-year experience]

Teaching strategies for a new specialty constitute a challenge to ensure the rapid development of human resources for the purpose of supporting these activities. In the health economics field a plan was applied for coping with the needs of teaching activities in the field. The activities developed in the plan are presented in this paper, included under the following items: A. Theoretical organization of the contents of the subject. B. Organization of contents according to the students' needs. C. Support given to teachers. D. The whole strategy also includes: academic interchange, technical advisory services, dissemination of results through meetings, publications and academic organizations. E. Median term agenda: Human resources; Financial resources; Teaching strategies; Interaction between health services and decision makers; and Collaborative network.

[Medical equipment companies and their ties with technology development centers in Mexico]

The purpose of this study was to determine the characteristics of the companies that produce, distribute, and service medical equipment in Mexico and the factors related to whether or not they had established ties with research and technology development centers. The data analyzed came from a survey of such companies carried out in Mexico City and environs in 1989. The information was updated in 1991. Multivariate analyses were carried out in order to identify the characteristics of companies that had established ties or wished to do so and the areas of interest of those companies. Of 208 companies surveyed, only 23% had ties with research centers. The companies that had such ties or were interested in establishing them tended to invest in research and to have made plans for expansion. The establishment of ties appeared to be a two-way process, with positive consequences for the companies involved, the research centers, and the health sector. It was concluded that it would be advantageous to design programs to promote ties with companies having the characteristics mentioned.

[Supply of medical equipment in Mexico]

This article covers the report on Supply of Medical Equipment in Mexico, presented during the Second National Congress of Public Health. The results are part of an investigation that dealt with the general conditions that currently prevail in the production and distribution of medical equipment. The information was obtained by means of a survey applied to 208 companies that comprised the sample study. The facts indicate that of the companies that correspond to this industrial sector in Mexico, 3.8 per cent are manufacturers, 69.7 per cent distributors, 19.2 per cent manufacturer-distributors, and the remaining 7.2 per cent correspond to corrective and preventive maintenance. Also, these companies pose serious problems of external dependence with regard to production costs and the commercialization of products. Furthermore, it became evident that there is a substantial need for financial support to optimally satisfy the demands of various institutions in the country's health sector.

[Explanatory models on the utilization of health services: a review and analysis]

The present article begins with a conceptual review of the models which have been developed for the analysis of health services utilization. The models are: epidemiological, psychosocial, sociological and economic. The stages and/or determining factors in the procedure of health services use, are described and a cross study is made with each model by means of a contingency matrix. The starting point for the search of a model that enables (in a complete and unisolated way) the identification of the determinant factors in health service use is the cross analysis of the models under investigation. This cross analysis is also taken as a conceptual framework of reference in the unfolding investigation.

[Investigation in medical technology: support for cooperation among countries]

This paper discusses the results of the research work on medical technology in several countries by research teams whose goals are to prompt the exchange of information and support practical cooperation. Emphasis is placed on the work developed by the Pan American Health Organization, which has supported 45 research proposals on medical technology and stimulated the association of academic groups, national institutions and international agencies. The authors also describe the research activities of the team devoted to medical technology research at the National Institute of Public Health in Mexico.