[Cancer mortality in Chile: epidemiological considerations]

Malignancies are the second most important cause of mortality in Chile, accounting for 21.8% of total deaths. In comparison with other causes, cancer mortality shows an upward trend with increasing mortality rates from 99 to 118 per 100.000 population in the period 1980-1998. The most important cancer locations are stomach, lung and prostate among men and gallbladder, stomach, breast and uterine cervix in women. According to present risks, the mean probability for a Chilean to die from cancer is 3.0% for stomach, 2.3% for prostate, 2.0% for lung, 1.7% for gallbladder, 1.6% for breast and 1.2% for uterine cervix cancer. Recent trends of cancer crude death rates are a matter of concern. During the period 1990-1998 a significant decrease of death rates was only noticed for uterine cervix cancers. On the other hand, important increases were observed for prostate, lung, gallbladder, colon and kidney cancers. If death rates are adjusted by age, an increased risk, not due to the population aging process, is noticed for prostate and to less extent for kidney, colon, skin and myeloma. The adjusted rates show a downward trend for uterine cervix, stomach, breast and esophagus cancer. Increasing cancer mortality is associated with diagnostic and therapeutic delays. Possible actions in screening programs are discussed.

The p38-MAPK/SAPK pathway is required for human keratinocyte migration on dermal collagen

Human keratinocyte motility plays an important role in the re-epithelialization of human skin wounds. The wound bed over which human keratinocytes migrate is rich in extracellular matrices, such as fibrin, fibronectin, and collagen, and serum factors, such as platelet-derived growth factor and transforming growth factor beta 1. Extracellular matrices and the serum factors bind to cell surface receptors and initiate a cascade of intracellular signaling events that regulate cell migration. In this study, we identified an intracellular signaling pathway that mediates collagen- driven motility of human keratinocytes. Pharmaco logic inhibition of the activation of p38-alpha and p38-beta mitogen-activated protein kinase activation potently blocked collagen-driven human keratinocyte migration. Transfection of the same keratinocytes with the kinase-negative mutants of p38-alpha or p38-beta mitogen-activated protein kinase markedly inhibited keratinocyte migration on collagen. Attachment of keratinocytes to collagen activated p38 mitogen- activated protein kinase, as well as p44/p42 ERKs. Interestingly, activation of the p38 mitogen-activated protein kinase cascade by overexpressing the constitutively active MKK3 and MKK6, MKK3b(E) and MKK6b(E), could neither initiate migration in the absence of collagen nor enhance collagen-driven migration. This study provides evidence that the p38-MAPK/SAPK pathway is necessary, but insufficient, for mediating human keratinocyte migration on collagen.

[Colonoscopic follow-up of patients undergoing curative resection of colorectal cancer]

AIM

To investigate the role of colonoscopy in the follow-up of patients undergoing curative resection of colorectal cancer.

MATERIAL AND METHODS

A prospective study was performed of 102 patients with colorectal cancer who underwent surgery with curative intention. Postoperative colonoscopic follow-up was a minimum of 5 years.

RESULTS

There were 62 males and 40 females. The mean duration of follow-up was 73.4 months. Synchronous polyps were found in 44.1% (114 in 45 patients) and metachronous polyps in 33.4% (64 in 34 patients). Synchronous carcinoma was detected in 7.8% (9 in 8 patients), metachronous carcinoma in 1.9% (2 in 2 patients) and suture recurrence in 4.9% (5 in 5 patients). Metachronous polyps developed in 55.5% of the patients with synchronous polyps and in only 15.8% of those with no synchronous polyps (p < 0.00005); the odds ratio was 6.67. Colonoscopy diagnosed 92 synchronous polyps and 64 metachronous polyps; of these, 34 were found to be significant(in 22 patients). Colonoscopy diagnosed 5 synchronous carcinomas; in 3 of these (polyps with non-invasive carcinoma) polypectomy constituted definitive therapy and in the remaining 2, curative resection was achieved. Colonoscopy diagnosed 2 stage C2 metachronous carcinomas at 63 and 94 months. Curative resection was achieved in both cases. Colonoscopic follow-up diagnosed 2 suture recurrences and resection was potentially curative.

CONCLUSIONS

Colonoscopy was found to play an essential role in 30% of the patients. The technique allowed the early diagnosis of synchronous carcinomas and curative treatment of metachronous carcinomas and demonstrated that the presence of synchronous polyps increases the risk of developing metachronous polyps.

Genetic control of susceptibility to group A streptococcal infection in mice

The influence of genetic background on the ability to control infection with group A streptococci was investigated in different inbred strains of mice. Whereas BALB/c, C57BL/10, and DBA/2 mice were the most resistant strains, with lower bacteria loads and higher survival times, C3H/HeN and CBA/J mice exhibited substantially higher bacterial growth and 100% mortality. Differences in susceptibility were not dependent on the inoculum size. Resistance was influenced by sex, with males being much more susceptible than females. B cell- and T cell-deficient mice from the resistant background were as resistant to infection as were immunocompetent mice, which suggests that the effector mechanisms are independent of adaptive immunity. These results demonstrate for the first time the influence of genetic background and sex on susceptibility to infection with Streptococcus pyogenes in mice. The use of this mouse model of group A streptococcal infection will allow for a better definition of parameters involved in the outcome of the disease.

Role played by the response regulator Ris in Bordetella bronchiseptica resistance to macrophage killing

Previous studies suggested that the persistence in eukaryotic cells of a Bordetella bronchiseptica mutant carrying an insertion in the locus encoding the response regulator RisAS is impaired. This suggested that ris-dependent products are required for the intracellular survival of bacteria. In this study we demonstrate that ris-regulated products play a role in B. bronchiseptica resistance against both phagosomal acidification and reactive oxygen intermediates.

From favorable atomic configurations to supershell structures: a new interpretation of conductance histograms

Simulated minimum cross-section histograms of breaking Al nanocontacts are produced using molecular dynamics. The results allow a new interpretation of the controverted conductance histogram peaks based on preferential geometrical arrangements of nanocontact necks. As temperature increases, lower conductance peaks decrease in favor of broader and higher conductance structures. This reveals the existence of shell and supershell structures favored by the increased mobility of Al atoms.

[Diet, smoking and reproductive history as risk factor for cervical cancer]

BACKGROUND

Epidemiological studies have suggested that smoking, nutrition and sexual patterns are major risk factors for cervical cancer.

AIM

To study the association between food consumption patterns, smoking and sexual behavior and the risk of cervical cancer.

MATERIAL AND METHODS

A matched case control study of 170 cases and 340 controls. Food and nutrient intakes were assessed by a food frequency questionnaire considering 58 antioxidant rich food items. Median daily intake of vegetables, fruits, antioxidant vitamins and fiber was calculated. A conditional logistic regression model was used to determine odds ratios associated with variations in nutritional intake and no nutritional factors (age at first delivery, parity, body mass index, family history of cancer and smoking).

RESULTS

High intakes of vegetables, fruits, beta carotene, vitamin C, E and fiber were associated with a lower risk of cervical cancer (Odds ratios ranging from 0.56 to 0.78). The risk for cancer was inversely associated with the age at first delivery and directly associated with the total number of pregnancies and smoking. Multivariate analysis model showed a protective effect for vegetable and vitamin E consumption (odds ratio of 0.6 with confidence intervals of 0.5 to 0.8 p < 0.001) and a higher risk associated to smoking (odds ratio 2.8, confidence intervals 1.5-5.5 p < 0.002) and a younger age at the first delivery (odds ratio 3.37 confidence intervals 2-5.3 p < 0.001).

CONCLUSIONS

Cervical cancer is associated with reproductive and food consumption behaviors. A higher intake of vegetables and foods rich in vitamin E can reduce its risk.

Use of live bacterial vaccine vectors for antigen delivery: potential and limitations

Most infectious agents are restricted to the mucosal membranes or their transit through the mucosa constitutes a critical step in the infection process. Therefore, the elicitation of an efficient immune response, not only at systemic, but also at mucosal level, after vaccination is highly desirable, representing a significant advantage in order to prevent infection. This goal can be only achieved, when the vaccine formulation is administered by the mucosal route. However, soluble antigens given by this route are usually poorly immunogenic. Among the available approaches to stimulate efficient mucosal responses, the use of bacterial carriers to deliver vaccine antigens, probably, constitutes one of the most successful strategies. The potential and limitations of the most extensively studied bacterial carrier systems will be discussed.

Covariate effects on the apparent clearance of tacrolimus in paediatric liver transplant patients undergoing conversion therapy

OBJECTIVE

To analyse the influence of covariates on the apparent clearance (CL) of tacrolimus in paediatric liver transplant recipients being converted from cyclosporin to tacrolimus.

DESIGN

Retrospective modelling study.

PATIENTS AND PARTICIPANTS

18 children, 13 girls and 5 boys, aged 4 months to 16 years (median 9.1 years) who required conversion to tacrolimus because of acute or chronic rejection or cyclosporin toxicity.

METHODS

287 whole-blood tacrolimus concentrations from therapeutic drug monitoring were used to build a nonlinear mixed-effects population model (NONMEM program) for the apparent clearance of tacrolimus. Variables considered were age, total bodyweight (TBW), body surface area (BSA), time after initiation of treatment (T), gender, haematocrit (Hct), albumin (Alb), aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (gammaGT), alkaline phosphatase (ALP), bilirubin (BIL), creatinine clearance (CL(CR)) and dosage of concomitant corticosteroids (EST).

RESULTS

TBW, T, BIL and ALT were the covariates that displayed a significant influence on CL according to the final regression model: CL (L/h) = 10.4(TBW/70)3/4 x e(-0.00032 T) x e(-0.057 BIL) x (1 - 0.079 ALT). With this model, the estimates of the coefficients of variation were 24.3% and 29.5% for interpatient variability in CL and residual variability, respectively.

CONCLUSIONS

The proposed model for tacrolimus CL can be applied for a priori dosage calculations, although the results should be used with caution because of the unexplained variability in the CL. We therefore recommended close monitoring of tacrolimus whole blood concentrations, especially within the first months of treatment. The best use of the model would be its application in dosage adjustment based on therapeutic drug monitoring and the Bayesian approach.

[Is it possible to have a consensual terminology in disc diseases?]

The large variety of concepts and classifications for disc disease (anatomical, pathological, surgical and radiological) are reflected in the, often ambiguous, terminology of degenerative disc disease used on imaging study reports by neuroradiologists and radiologists. The attempts to standardize the nomenclature, made by some medical societies, lack general acceptance. This work reflects the conviction that morphological characterization of disc disease prevails over the anatomopathological due to the limitations of imaging study techniques, including magnetic resonance imaging.

Characterization of the domain of fibronectin-binding protein I of Streptococcus pyogenes responsible for elicitation of a protective immune response

Fibronectin-binding protein I (SfbI) represents a major adhesin of Streptococcus pyogenes. Mice were intranasally immunized with recombinant proteins spanning different portions of SfbI to identify the minimal fragment able to elicit a protective response against a lethal challenge with S. pyogenes. The strongest cellular responses and the highest levels of antigen-specific secretory immunoglobulin A (IgA) were detected in mice immunized with the fibronectin-binding region of SfbI. In contrast, animals vaccinated with a polypeptide spanning the aromatic and proline-rich regions showed the highest titers and fastest IgG response in serum. Vaccination with either SfbI without a membrane anchor and signal peptide or a polypeptide encompassing its fibronectin-binding regions resulted in efficient protection against heterologous challenge (60% and 80%, respectively), whereas the use of a polypeptide lacking this region conferred marginal protection (10%) with respect to the control group (0%). These results demonstrate that the fibronectin-binding region of SfbI is a promising candidate antigen for developing anti-S. pyogenes vaccines.

[Adult mortality in Chile]

BACKGROUND

The study of mortality of human groups is important to judge the health conditions of population.

AIM

To study the main mortality features among Chilean adults.

MATERIAL AND METHODS

Information about mortality in Chile from the Instituto nacional de Estadísticas and The World Health Organization, was analyzed. Data was expressed mainly as rates.

RESULTS

Annual mortality risk among Chileans is 812 per 100,000 inhabitants and is low compared to the rest of Latin America. In the last 30 years it has decreased systematically at a rate of 1% per year in both genders. The risk of mortality caused by cerebrovascular disease, coronary heart disease, hepatic cirrhosis, gastric cancer and tuberculosis has decreased. On the other hand, the risk of mortality caused by diabetes, hypertension and lung, gallbladder, prostate and colorectal cancer has increased. Mortality varies from 604 per 100,000 in Atacama to 934 per 100,000 in Valparaiso. The most factor that influences this variation is population aging. Mean survival at the start of adulthood is 54 years in men and 61 years in women. At 60 years, the expectancy is 19 and 24 years respectively. Mean age of death in Chile was 71.5 years in 1998. Seventy six percent of deaths occurs in the elderly and 33%, in people of 80 years or more.

CONCLUSIONS

Chile is one of the four Latin American countries with lower mortality risk. In the last 30 years, the main causes of deaths among adults, with exception of pneumonia, have decreased. Therefore health care of the adult is in the correct track (Rev Méd Chile 2000; 128: 1144-49).

Number and size of stones in patients with asymptomatic and symptomatic gallstones and gallbladder carcinoma: a prospective study of 592 cases

The development of gallbladder carcinoma has been correlated with the presence of a single large gallstone in two retrospective studies. The objective of the present study was to determine the number and size of gallstones in patients with gallbladder carcinoma compared to asymptomatic and symptomatic female patients with gallstones. The following three groups of patients were included in this prospective trial: (A) 78 asymptomatic patients with gallstones; (B) 365 symptomatic patients with gallstones; and (C) 149 patients with gallbladder carcinoma. At the end of the operation, the resected gallbladder was opened and the number of stones counted. The maximum size of the stones was determined using calipers. Patients with gallbladder carcinoma were significantly older than patients in the other two groups (P <0.001). In the group with asymptomatic gallstones, there were significantly more patients with one single stone, whereas in the group with gallbladder carcinoma there were significantly more patients with multiple stones (more than 11; P <0.01). Patients with gallbladder carcinoma had significantly larger stones, regardless of the number of stones present (P <0.001). We postulate that the increase in the number and size of the stones among patients with gallbladder carcinoma could simply be an effect of aging or it could be a reflection of the long-term presence of stones in the gallbladder rather than some particular chemical or physical influence.

[Diagnosis and treatment of hepatic artery thrombosis after liver transplantation]

The aim of this study was to examine the clinical presentation and time of hepatic artery thrombosis (HAT) after orthotopic liver transplantation (OLT), stressing the role of imaging modalities. Therapeutic options are described, such as retransplantation (Re-OLT), hepatic resections and revascularization procedures, focusing on complications and outcome in a consecutive series of 687 OLT. Over the period from 1986 to 1999, 687 OLT were carried out in 601 patients, 592 of whom were adults and 95 pediatric subjects. Of these operations 601 were primary OLT and 86 Re-OLT (71 I Re-OLT, 14 II Re-OLT and 1 III Re-OLT). In this retrospective study, we reviewed rejection episodes, time of HAT (early or late), possible cause of HAT, day of suspected diagnosis of HAT and day of confirmation of diagnosis. Clinical presentation, management, complications, outcome, survival rates and the need for Re-OLT were also recorded. The incidence of HAT was 2.47% (17/687). Early HAT (n = 9, < 30 days) was diagnosed 15.6 days after OLT (range: 3-25 days), whereas late HAT (n = 8, > 30 days) occurred 295.1 days after OLT (range: 38-1830 days). In two asymptomatic patients (2/17: 11.7%), HAT was discovered incidentally. Most of the patients (11/17: 64.7%) presented with increased liver function test values and fever. Relapsing bacteremia occurred in 7/17 cases (41.1%), whereas a biliary stricture and biliary leak were diagnosed in 3/17 (17.6%) and in 1/17 patients (5.8%), respectively. Fulminant hepatic failure was the clinical presentation in 2/17 cases (11.7%). In one case the clinical presentation was acute and chronic rejection (1/17: 5.8%). Intrahepatic abscesses were diagnosed in one case (1/17: 5.8%), as well as an intrahepatic haemorrhage (1/17: 5.8%). Doppler ultrasound (DUS) correctly revealed HAT in 9 of the 17 patients (52.9% sensitivity). In 8 of the 9 patients (88.8%) in whom HAT was diagnosed by DUS, angiography was also performed to confirm the diagnosis. Overall, angiography detected HAT in 14/17 patients (82.3% sensitivity). HAT management consisted of immediate Re-OLT in 6 patients 6.8 days (range: 3-12 days) after diagnosis. Delayed Re-OLT was performed in 6 patients 529.1 days (range: 68-1920 days) after diagnosis. The overall retransplantation rate was 70.5% (12/17). Two patients died despite undergoing intraarterial urokinase treatment. Three grafts were salvaged, but suffered biliary stricture due to ischemic cholangitis and underwent hepatico-jejunostomy. A II Re-OLT was carried out in 4 of 12 patients (33.3%). The overall mortality rate was 41.1% (7/17). One-year and 3-year overall survival rates were 58.8% (10/17) and 47.0% (8/17), respectively. Both 5- and 10-year overall survival rates were 11.7% (2/17). Although the results of OLT have improved dramatically over the past few years, HAT is still associated with substantial morbidity, a high incidence of graft failure and high mortality rates. The use of DUS to screen for HAT has permitted earlier diagnosis, but early angiographic evaluation of the hepatic arteries is still needed for accurate diagnosis of HAT and remains the gold standard. Retransplantation is the definitive solution for HAT in the majority of cases, though it is essentially the patient's clinical condition that dictates the form of management.

Development and characterization of a recombinant truncated type VII collagen "minigene". Implication for gene therapy of dystrophic epidermolysis bullosa

Dystrophic epidermolysis bullosa (DEB) is an inherited mechano-bullous disorder of skin caused by mutations in the type VII collagen gene. The lack of therapy for DEB provides an impetus to develop gene therapy strategies. However, the full-length 9-kilobase type VII collagen cDNA exceeds the cloning capacity of current viral delivery vectors. In this study, we produced a recombinant type VII minicollagen containing the intact noncollagenous domains, NC1 and NC2, and part of the central collagenous domain using stably transfected human 293 cell clones and purified large quantities of the recombinant minicollagen VII from culture media. Minicollagen VII was secreted as correctly-folded, disulfide-bonded, helical trimers resistant to protease degradation. Purified minicollagen VII bound to fibronectin, laminin-5, type I collagen, and type IV collagen. Furthermore, retroviral-mediated transduction of the minigene construct into DEB keratinocytes (in which type VII collagen was absent) resulted in persistent synthesis and secretion of a 230-kDa recombinant minicollagen VII. In comparison with parent DEB keratinocytes, the gene-corrected DEB keratinocytes demonstrated enhanced cell-substratum adhesion, increased proliferative potential, and reduced cell motility, features that reversed the DEB phenotype toward normal. We conclude that the use of the minicollagen VII may provide a strategy to correct the cellular manifestations of gene defects in DEB.

Nonimmune interaction of the SfbI protein of Streptococcus pyogenes with the immunoglobulin G F(ab')(2) fragment

Fibronectin-binding protein I (SfbI) of Streptococcus pyogenes binds to mouse immunoglobulin G (IgG) but not to IgA or IgM in a nonimmune fashion. The fibronectin-binding domains of SfbI were responsible for this activity, which was targeted to the IgG F(ab')(2) fragment. SfbI also binds to B cells but not to CD4(+) or CD8(+) lymphocytes.

Diagnosis of arterial injuries caused by penetrating trauma to the neck: comparison of helical CT angiography and conventional angiography

PURPOSE

To determine the sensitivity and specificity of helical computed tomographic (CT) angiography in the diagnosis of carotid and vertebral arterial injuries caused by penetrating neck trauma.

MATERIALS AND METHODS

A prospective study was conducted during 24 months in 60 patients with penetrating neck trauma who were referred for conventional angiography owing to clinical suspicion of arterial injury. In the patient population, 146 arteries (77 carotid, 69 vertebral) were studied by means of conventional angiography. In all patients, conventional angiography and helical CT angiography were completed within 6 hours. Two radiologists interpreted helical CT angiographic studies by means of consensus. Conventional angiography was the standard of reference for determining the sensitivity and specificity of helical CT angiography.

RESULTS

Conventional angiograms showed arterial injuries in 10 (17%) of 60 patients. Conventional angiographic findings were arterial occlusion (n = 4), arteriovenous fistula (n = 2), pseudoaneurysm (n = 3), pseudoaneurysm with arteriovenous fistula (n = 1), and normal arteries (n = 136). Nine of 10 arterial injuries and all normal arteries were depicted adequately at helical CT angiography. Sensitivity of helical CT angiography was 90%, specificity was 100%, positive predictive value was 100%, and negative predictive value was 98%.

CONCLUSION

The sensitivity and specificity of helical CT angiography are high for detection of major carotid and vertebral arterial injuries resulting from penetrating trauma.

Subchronic administration of sublethal doses of thallium to rats: effects on distribution and lipid peroxidation in brain regions

Occupational exposure to thallium (Tl+) is known to be responsible for severe neurological manifestations in humans, including ataxia and paralysis; however, little is known yet about the precise mechanism of toxicity elicited by this heavy metal at sublethal doses and its brain distribution after chronic or subchronic exposures resulting from environmental contamination. In order to evaluate the levels of Tl in rat brain regions after a subchronic administration (30 days) of sublethal doses of Tl (I) acetate: 0.8 mg/kg (1/40 of LD(50)), 1.6 mg/kg (1/20 of LD(50)), we measured the concentrations of Tl by atomic absorption spectrophotometry. A possible role of oxidative injury in the pattern of toxicity exerted by Tl in the same brain regions, was also studied. Lipid peroxidation (LP) as a current marker of oxidative stress, was estimated by the generation of lipid fluorescent products. Higher concentrations of Tl were observed in brain tissue from adult rats treated with 1.6 mg/kg, as compared to those treated with 0.8 mg/kg. However, no differential distribution of Tl among regions was observed after administration of 0.8 mg/kg dose to rats, nor after 1. 6 mg/kg dose. We also found significant changes in LP both in corpus striatum and cerebellum from rats treated daily with 0.8 mg/kg Tl, whereas all regions from rats treated with 1.6 mg/kg Tl exhibited enhanced LP as compared to control. These findings suggest an active role of free radicals and oxidative events involved in the pattern of toxicity after exposure to sublethal doses of Tl, which are associated with regional susceptibility of the brain to this metal.

Environmental factors associated with blood lead levels in Venezuelan children

A preliminary study explored the relative contribution of residential sources of lead exposure on mentally challenged children who attend "special education" institutions (GI) compared to a group of age and sex matched school children (G2). We captured descriptive information and analyzed demographic variables, personal and household information, medical effects, environmental exposure factors, and children habits. Home paint, dust, soil, and water sampling was conducted and blood lead (BPb) levels determined. Eighteen G1 and 20 G2 children were studied. The mean G1 BPb was 16.9 +/- 7.9 microg/dl and was significantly higher than that in G2. Fifty percent of G1 children had PbB >20 microg/dl and 72.2% were >10 microg/dl. Low muscular strength, decreased osteotendinose reflexes, fine and gross motricity, deficient equilibrium, and hipotonic muscular tone coincided with >18 microg/dl BPb levels. In 61.1% of G1 homes paint lead levels were higher than permissible levels and 33.3% had dust lead exceeding that level. The high BPb levels in G1 probably resulted from ingestion of household paint, dust, and soil via "hand-to-mouth" activity. Environmental exposure to lead can be an important source of lead intake by infants and children and could affect neurological development. This study provides new insights currently unavailable for these children in Venezuela.

Leaf optical properties in Venezuelan cloud forest trees

Leaf optical properties and related leaf characteristics were compared for thirteen cloud forest tree species differing in successional status. Sun leaves were sampled for the eight pioneer species and sun and shade leaves were sampled for the five climax species. Sun leaves had a slightly higher absorptance than shade leaves, although differences were small. Sun leaves had a higher leaf mass per unit area (LMA) and a lower chlorophyll concentration per unit leaf mass, resulting in similar chlorophyll concentrations per unit leaf area and hence similar light harvesting capacities as shade leaves. However, shade leaves realized a higher efficiency of absorptance per unit leaf biomass than sun leaves. There were few differences in leaf characteristics of sun leaves between the climax and pioneer species. Absorptance values of cloud forest species were comparable with values reported for rain forest and more seasonal forest species. Intraspecific variation in leaf absorptance was largely the result of variation in LMA, whereas interspecific variation in leaf absorptance was largely a result of variation in chlorophyll concentration per unit leaf area.

Modulation of immune responses following antigen administration by mucosal route

Most microbial infections are either restricted to the mucosal membranes or the etiologic agents needed to transit the mucosa. Thus, it is desirable to stimulate a mucosal response following vaccination, to block both infection and disease development. Attenuated vaccine carriers mimic natural infections, triggering also mucosal responses. Similar results can be achieved by administering antigens with appropriate adjuvants. However, the delivery of antigens per se is not sufficient to engender a protective response. A successful immunization requires the elicitation of an appropriate type of immune response (e.g. antibodies vs. cell-mediated immunity, Th1 vs. Th2 helper pattern). Therefore, a successful vaccination strategy demands the choice of adequate antigens, and their appropriate delivery and/or formulation to promote the required quality of immune response. Different strategies to optimize the immune responses elicited following vaccine administration by the mucosal route are discussed.

Modulation of host immune responses stimulated by Salmonella vaccine carrier strains by using different promoters to drive the expression of the recombinant antigen

We evaluated whether immune responses stimulated by Salmonella vaccine carriers can be modulated by using different promoters to drive antigen expression. Mice were orally immunized with strains transfected with plasmids carrying beta-galactosidase (beta-gal) under the control of either a constitutive or an in vivo-activated promoter. While alpha-gal-reactive IgG1, IgG2a, IgG2b and IgG3 were detected in sera of mice immunized with Salmonella expressing constitutively beta-gal, higher titers dominated by IgG2a and IgG2b were detected in sera when the in vivo-activated promoter was used. beta-gal-specific proliferative responses of spleen-derived CD4+ T lymphocytes were similar in both groups. However, CD4+ T lymphocytes from mice immunized with the constitutive promoter secreted IL-4, IL-5, IL-6, IL-10 and IFN-gamma (Th1/Th2 pattern), whereas CD4+ cells mainly secreted IFN-gamma (Th1 pattern) when the second construct was used. The spleens of all immunized mice contained beta-gal-reactive CD8+ CTL precursors. The vaccine prototypes were tested for their capacity to control seeding and/or development within the lung of an intravenously delivered aggressive fibrosarcoma transfected with beta-gal. Reduced metastasis and significantly increased mean survival times were observed in all vaccinated mice. However, protection was improved when the carrier expressed beta-gal upon infection (80 % versus 50% survival, p < 0.05).

[Breast cancer risk factors in women in Santiago, Chile]

BACKGROUND

Epidemiological studies suggest a relation between breast cancer, diet and life styles.

AIM

To analyze the association between food patterns, obesity, smoking, alcohol consumption and breast cancer risk in women of Santiago.

PATIENTS AND METHODS

A case-control study design (170 cases and 340 controls), matched by age and sex, was used. Through a food frequency questionnaire the average daily intake of vegetables, fruits, beta-carotene, vitamin A, C, E and fiber was analyzed. Other exposures to non-nutritional risks (parity, smoking, cancer history) were also studied. Conditional logistic regression was calculated to determine the odds ratio associated with variations in food and nutrient intake and non-nutritional factors.

RESULTS

Cases had a greater BMI and a higher prevalence of obesity than controls (p < 0.02). No differences were observed in either group food patterns. The ORs for breast cancer associated with obesity and alcohol consumption were 1.65 (95% CI 1.06-2.64) and 1.61 (95% CI 1.06-2.54) respectively (p < 0.05). Multiparity had a protective effect with 0.66 less risk (95% CI 0.44-0.99). No protective effect associated to a greater intake of vegetables, fruits or natural antioxidants was observed. Multivariate analysis model disclosed obesity as a risk factor (OR 1.79, p < 0.02) and parity > or = 4 as protective (OR 0.62, p < 0.02).

CONCLUSIONS

This study does not support a protective role for natural antioxidants against breast cancer but indicate a weak association with obesity.

[Neurophysiological clinical study of 70 patients with type 2 spinocerebellar ataxia]

INTRODUCTION

The prevalence of hereditary ataxia in Holguín, Cuba, is 43 per 100,000 inhabitants, but in some regions reaches 503 per 100,000 inhabitants, a figure never previously recorded in the international literature.

OBJECTIVES

To evaluate the part played by non-cerebellar structures and vias in causing some of the clinical signs of the disorder by means of clinico-electro physiological correlation.

PATIENTS AND METHODS

A neurological examination, peripheral nerve conduction studies and somato-sensorial evoked potentials of the median and posterior tibial nerves were done in 70 patients with type 2 spinocerebellar ataxia.

RESULTS

The commonest clinical signs were ataxia on walking, dysarthria, dysmetria and adiadochokinesia. Correlation analysis showed that the variable most significantly correlated with the degree of ataxia and Romberg's sign was latency of the P40 component, whilst tendon reflexes were best correlated with H reflex latency. However, the duration of the disease was not found to have statistical correlation.

CONCLUSIONS

These results suggest that degeneration of long peripheral nerves and sensory paths contributes to the degree of ataxia and other clinical signs. At present no correlation has been found between the duration of the illness and increasing electrophysiological changes, and therefore seems not to have a major effect on neurodegenerative mechanisms.