A study of the genetical structure of the Cuban population: red cell and serum biochemical markers. (1/401)

Gene frequencies of several red cell and serum gentic markers were determined in the three main racial groups--whites, mulattoes and Negroes--of the Cuban population. The results were used to estimate the relative contribution of Caucasian and Negro genes to the genetic makeup of these three groups and to calculate the frequencies of these genes in the general Cuban population.  (+info)

The challenge for Cuba. (2/401)

The restrictions of a U.S. trade embargo and the collapse of the Soviet Union marked the beginning of a period of extreme economic hardship in Cuba. Economic adversity has had tremendous effects, both positive and negative, on all aspects of life on the Island, including environmental and public health.  (+info)

Acquired mitochondrial impairment as a cause of optic nerve disease. (3/401)

BACKGROUND: Blindness from an optic neuropathy recently occurred as an epidemic affecting 50,000 patients in Cuba (CEON) and had clinical features reminiscent of both tobacco-alcohol amblyopia (TAA) and Leber's hereditary optic neuropathy (Leber's; LHON). Selective damage to the papillomacular bundle was characteristic, and many patients also developed a peripheral neuropathy. Identified risk factors included vitamin deficiencies as well as exposure to methanol and cyanide. In all 3 syndromes, there is evidence that singular or combined insults to mitochondrial oxidative phosphorylation are associated with a clinically characteristic optic neuropathy. PURPOSE: First, to test the hypothesis that a common pathophysiologic mechanism involving impairment of mitochondria function and, consequently, axonal transport underlies both genetic optic nerve diseases such as Leber's and acquired toxic and nutritional deficiency optic neuropathies. According to this hypothesis, ATP depletion below a certain threshold leads to a blockage of orthograde axonal transport of mitochondria, which, in turn, leads to total ATP depletion and subsequent cell death. Second, to address several related questions, including (1) How does impaired energy production lead to optic neuropathy, particularly since it seems to relatively spare other metabolically active tissues, such as liver and heart? (2) Within the nervous system, why is the optic nerve, and most particularly the papillomacular bundle, so highly sensitive? Although there have been previous publications on the clinical features of the Cuban epidemic of blindness, the present hypothesis and the subsequent questions have not been previously addressed. METHODS: Patients in Cuba with epidemic optic neuropathy were personally evaluated through a comprehensive neuro-ophthalmologic examination. In addition, serum, lymphocytes for DNA analysis, cerebrospinal fluid (CSF), sural nerves, and eyes with attached optic nerves were obtained from Cuban patients, as well as from Leber's patients, for study. Finally, we developed an animal model to match the low serum folic acid and high serum formate levels found in the CEON patients, by administering to rats low doses of methanol after several months of a folic acid-deficient diet. Optic nerves and other tissues obtained from these rats were analyzed and compared with those from the Cuban patients. RESULTS: Patients from the Cuban epidemic of optic neuropathy with clinical evidence of a selective loss of the papillomacular bundle did much better once their nutritional status was corrected and exposure to toxins ceased. Patients with CEON often demonstrated low levels of folic acid and high levels of formate in their blood. Histopathologic studies demonstrated losses of the longest fibers (in the sural nerve) and those of smallest caliber (papillomacular bundle) in the optic nerve, with intra-axonal accumulations just anterior to the lamina cribrosa. Our animal model duplicated the serologic changes (low folic acid, high formate) as well as these histopathologic changes. Furthermore, ultrastructural examination of rat tissues demonstrated mitochondrial changes that further matched those seen on ultrastructural examination of tissues from patients with Leber's. CONCLUSION: Mitochondria can be impaired either genetically (as in Leber's) or through acquired insults (such as nutritional or toxic factors). Either may challenge energy production in all cells of the body. While this challenge may be met through certain compensatory mechanisms (such as in the size, shape, or number of the mitochondria), there exists in neurons a threshold which, once passed, leads to catastrophic changes. This threshold may be that point at which mitochondrial derangement leads to such ATP depletion that axonal transport is compromised, and decreased mitochondrial transport results in even further ATP depletion. Neurons are singularly dependent on the axonal transport of mitochondria. (  (+info)

The epidemiological impact of antimeningococcal B vaccination in Cuba. (4/401)

The incidence of invasive meningococcal disease (IMD) before (1984-1988) and after (1989-1994), a nationwide intervention with VA-MENGOC-BC vaccination started in 1989, was compared. The prevaccination period incidence density (ID> 8.8/10(5) year-person) was higher than the postvaccination ID (ID< 6.5/10(5) year-person). The percentage proportional differences from the start to the end of each period of ID in the vaccinal period was higher (87%) than the prevaccinal (37%) with significant differences among vaccinated groups (< 25 years old). A break-point (Chow test) was confirmed by the decrease in the ID between 1989 and 1990 in children under 1 year old, 5-9, 10-14, 15-19 and 50-54 years. Comparison of ID using maps showed a decrease in IMD in all municipalities during the postvaccination period. These findings support the epidemiological impact of VA-MENGOC-BC vaccination in the reduction of IMD morbidity.  (+info)

Antigenic and genetic characterization of twenty-six strains of human respiratory syncytial virus (subgroup A) isolated during three consecutive outbreaks in Havana city, Cuba. (5/401)

Twenty-six human respiratory syncytial virus strains (subgroup A) isolated from three outbreaks in Havana City during the period 1994/95, 1995/96 and 1996/97 were analyzed to determine their antigenic and genetic relationships. Analyses were performed by monoclonal antibodies and restriction mapping (N gene) following amplification of the select region of the virus genome by polymerase chain reaction. All isolated strains were classified as subgroup A by monoclonal antibodies and they showed a restriction pattern NP4 that belonged to subgroup A. Thus the results obtained in this work, showed a close relation (100%) between antigenic and genetic characterization of the isolated strains in our laboratory. These methods permit the examination of large numbers of isolates by molecular techniques, simplifying the researchs into the molecular epidemiology of the virus.  (+info)

The Latino mortality paradox: a test of the "salmon bias" and healthy migrant hypotheses. (6/401)

OBJECTIVES: Relative to non-Latino Whites, Latinos have a worse socioeconomic profile but a lower mortality rate, a finding that presents an epidemiologic paradox. This study tested the salmon bias hypothesis that Latinos engage in return migration to their country of origin and are thereby rendered "statistically immortal" and the alternative hypothesis that selection of healthier migrants to the United States accounts for the paradox. METHODS: National Longitudinal Mortality Study data were used to examine mortality rates of the following groups for whom the salmon hypothesis is not feasible: Cubans, who face barriers against return migration; Puerto Ricans, whose deaths in Puerto Rico are recorded in US national statistics; and US-born individuals, who are not subject to either salmon or healthy migrant effects. RESULTS: The sample included 301,718 non-Latino Whites and 17,375 Latino Whites 25 years or older. Cubans and Puerto Ricans had lower mortality than non-Latino Whites. Moreover, US-born Latinos had lower mortality than US-born non-Latino Whites. CONCLUSIONS: Neither the salmon nor the healthy migrant hypothesis explains the pattern of findings. Other factors must be operating to produce the lower mortality.  (+info)

Eradication of poliomyelitis in Cuba: a historical perspective. (7/401)

The eradication of poliomyelitis in Cuba, for which effective vaccines had to be acquired, is reviewed in this article. The strategy for eradication was based on mass immunization campaigns for the annual delivery of two doses of trivalent Sabin oral poliovirus vaccine (OPV). Except during the first campaign in 1962, the ages of the children for immunization were determined through national serological surveys of the entire country, including rural and urban areas. The interruption of wild virus transmission had been suspected since 1967 in Cuba, and since 1970 no studies have detected any wild virus. The important role of political and social organizations in the success of the programme and in the execution of the mass immunization campaigns is underscored. Countries that have successfully interrupted poliovirus circulation should maintain high immunization coverage for as long as there are other countries in the world where poliovirus still exists.  (+info)

Difference between observed and predicted length of stay as an indicator of inpatient care inefficiency. (8/401)

OBJECTIVES: To evaluate the performance of the difference between observed and predicted length of stay (OLOS-PLOS) as an inefficiency of care indicator for inpatients. SETTING: The Internal Medicine and the General Surgery departments of Hermanos Ameijeiras Hospital in Havana. DESIGN AND STUDY PARTICIPANTS: Two sets of clinical histories were needed for each department: one for deriving the predictive equation and another to validate it. The equation was a linear multiple regression model which included variables recognized as affecting length of stay. The validation group of histories was thoroughly examined and separated into two groups: (i) adequate efficiency or mild problems and (ii) inefficiencies considered to be moderate or severe. This classification was the gold standard to obtain a receiver operating characteristic (ROC) curve for the indicator. RESULTS: The function explained 41% of the total variation for Internal Medicine and 70% for General Surgery. The indicator's mean difference between the two validation groups of histories was around 10 days for both departments. The areas under the ROC curve were 0.80 for Internal Medicine and 0.88 for General Surgery. Sensitivity and specificity > 0.7 for detecting inefficiencies of care are achieved with a cut off point of 2 days for Internal Medicine and 1 day for General Surgery. CONCLUSIONS: The use of predictive equations might be quite useful for detecting efficiency problems in inpatient health care.  (+info)