Pathophysiology of the basal ganglia in Parkinson's disease

Insight into the organization of the basal ganglia in the normal, parkinsonian and L-dopa-induced dyskinesia states is critical for the development of newer and more effective therapies for Parkinson's disease. We believe that the basal ganglia can no longer be thought of as a unidirectional linear system that transfers information based solely on a firing-rate code. Rather, we propose that the basal ganglia is a highly organized network, with operational characteristics that simulate a non-linear dynamic system.

Human immunodeficiency virus infection modifies the natural history of chronic parenterally-acquired hepatitis C with an unusually rapid progression to cirrhosis

BACKGROUND/AIMS

To investigate the possible role of HIV infection in the natural history of chronic parenterally-acquired hepatitis C.

METHODS

A multicenter cross-sectional study was performed in 547 patients with chronic parenterally-acquired hepatitis C with or without HIV infection (116 HIV-positive and 431 HIV-negative). Approximate duration of HCV infection was estimated in all patients included, and histologic diagnoses made at different time intervals following HCV infection were analyzed in both groups. Factors related to serum HCV-RNA levels were also investigated.

RESULTS

Histologic findings were similar in liver biopsies from both HIV-infected and noninfected patients. However, in the first 10 years, 13 out of 87 (14.9%) HIV-positive subjects developed cirrhosis, in comparison with 7 out of 272 (2.6%) in the HIV-negative group (p < 0.01). Similar results were found in the first 5 and 15 years, respectively, and most of the HIV-negative patients with cirrhosis (42 out of 56) developed cirrhosis in a time interval longer than 15 years. Consequently, mean interval from estimated time of HCV infection to cirrhosis was significantly longer in HIV-negative than HIV-positive patients (23.2 vs. 6.9 years; p < 0.001). Chronic active hepatitis (with and without cirrhosis) and long duration of HCV infection were significantly associated with higher HCV load (p < 0.05). Finally, HIV-positive patients with CD4+ cell counts > 500 cells/ml showed a lower HCV load than those with < 500 cells/ml (p < 0.05).

CONCLUSIONS

HIV infection modifies the natural history of chronic parenterally-acquired hepatitis C with an unusually rapid progression to cirrhosis. HIV-related immunodeficiency may be a determinant of higher hepatitis C viremia levels and more severe liver damage.

Income-related inequalities in health: some international comparisons

This paper presents evidence on income-related inequalities in self-assessed health in nine industrialized countries. Health interview survey data were used to construct concentration curves of self-assessed health, measured as a latent variable. Inequalities in health favoured the higher income groups and were statistically significant in all countries. Inequalities were particularly high in the United States and the United Kingdom. Amongst other European countries, Sweden, Finland and the former East Germany had the lowest inequality. Across countries, a strong association was found between inequalities in health and inequalities in income.

A novel GSK-3beta inhibitor reduces Alzheimer's pathology and rescues neuronal loss in vivo

Amyloid deposits, neurofibrillary tangles, and neuronal cell death in selectively vulnerable brain regions are the chief hallmarks in Alzheimer's (AD) brains. Glycogen synthase kinase-3 (GSK-3) is one of the key kinases required for AD-type abnormal hyperphosphorylation of tau, which is believed to be a critical event in neurofibrillary tangle formation. GSK-3 has also been recently implicated in amyloid precursor protein (APP) processing/Abeta production, apoptotic cell death, and learning and memory. Thus, GSK-3 inhibition represents a very attractive drug target in AD and other neurodegenerative disorders. To investigate whether GSK-3 inhibition can reduce amyloid and tau pathologies, neuronal cell death and memory deficits in vivo, double transgenic mice coexpressing human mutant APP and tau were treated with a novel non-ATP competitive GSK-3beta inhibitor, NP12. Treatment with this thiadiazolidinone compound resulted in lower levels of tau phosphorylation, decreased amyloid deposition and plaque-associated astrocytic proliferation, protection of neurons in the entorhinal cortex and CA1 hippocampal subfield against cell death, and prevention of memory deficits in this transgenic mouse model. These results show that this novel GSK-3 inhibitor has a dual impact on amyloid and tau alterations and, perhaps even more important, on neuronal survival in vivo further suggesting that GSK-3 is a relevant therapeutic target in AD.

EEG delta activity: an indicator of attention to internal processing during performance of mental tasks

In previous papers we proposed that an increase in delta EEG activity during mental tasks might be related to an increase in subjects' attention to internal processing. In this paper we have made a narrow band analysis to detect those EEG frequencies that change selectively during the performance of a mental task that requires attention to internal processing. Two different experiments were performed: (1) a difficult mental calculation task and a control stimulus with the same physical characteristics as the arithmetical symbols were presented in random order; (2) the Sternberg paradigm for the analysis of short term memory using a memory set of 5 or 3 digits was also presented in random order. Referential recordings to linked ears were obtained in all leads of the 10/20 system. In the first experiment, the increase of power from 1.56 to 5.46 Hz was observed only during the performance of the task and not during the control condition. In the Sternberg paradigm, the increase of power from 1.56 to 3.90 Hz was greater during the difficult than during the easy condition. These results support our hypothesis that an increase in delta activity may be related to attention to internal processing during the performance of a mental task.

Concomitant cisplatin chemotherapy and radiotherapy in advanced mucosal squamous cell carcinoma of the head and neck. Long-term results of the Radiation Therapy Oncology Group study 81-17

One hundred twenty-four eligible patients with advanced mucosal squamous cell carcinoma of the head and neck were entered into a pilot study of concomitant cisplatin (100 mg/m2 given every 3 weeks for three doses) and standard irradiation. The initial complete response (CR) was 71% with an additional two cases salvaged by surgery for an overall 73% CR. When no keratin was identified in the histologic specimen (41 patients) the CR was 90%. The nasopharynx showed the best CR (89%) among the sites. At 4 years after treatment, the estimated locoregional tumor control rate was 43% and the survival, 34%. When no keratin was present in the specimen, the estimated locoregional control of tumor was superior (56% versus 38% with keratin identified, P = 0.02) and the estimated survival was also superior (48% versus 26%, P = 0.008). Acute treatment-related toxicities included one death due to renal damage and two patients with life-threatening renal damage. The delivery of radiotherapy was not altered. Late toxicity included necrosis -3%, fibrosis -4%, and one fistula. The results of this study justify a randomized trial for the comparison of this combination of cisplatin and radiotherapy versus radiotherapy alone in advanced mucosal carcinomas of the head and neck.

Field studies and cost-effectiveness analysis of vaccination with Gavac against the cattle tick Boophilus microplus

The control of tick infestations and the transmission of tick-borne diseases remains a challenge for the cattle industry in tropical and subtropical areas of the world. Traditional control methods have been only partially successful and the parasites continue to result in significant losses for the cattle industry. Recently, vaccines containing the recombinant Boophilus microplus gut antigen Bm86 have been developed. These vaccines have been shown to control tick infestations in the field. However, extensive field studies investigating the efficacy and cost-effectiveness of vaccination have not been reported and are needed to appraise the effect of this new approach for tick control. Here is reported the results of the application of Gavac in a field trial including more than 260,000 animals in Cuba. In this study the correlation between the antibody response to vaccination and the effect on ticks fertility is determined. Physiological status of the animals was found to affect the primary response to vaccination but not the antibody titers after revaccination. A cost-effectiveness analysis showed a 60% reduction in the number acaricide treatments, together with the control of tick infestations and transmission of babesiosis, which resulted in savings of $23.4 animal-1 year-1. These results clearly demonstrate the advantage of vaccination and support the application of Gavac for tick control.

Equity in the finance of health care: some further international comparisons

This paper presents further international comparisons of progressivity of health care financing systems. The paper builds on the work of Wagstaff et al. [Wagstaff, A., van Doorslaer E., et al., 1992. Equity in the finance of health care: some international comparisons, Journal of Health Economics 11, pp. 361-387] but extends it in a number of directions: we modify the methodology used there and achieve a higher degree of cross-country comparability in variable definitions; we update and extend the cross-section of countries; and we present evidence on trends in financing mixes and progressivity.

Activation of glycogen synthase kinase-3 beta mediates β-amyloid induced neuritic damage in Alzheimer's disease

β-Amyloid (Aβ) plaques in Alzheimer (AD) brains are surrounded by severe dendritic and axonal changes, including local spine loss, axonal swellings and distorted neurite trajectories. Whether and how plaques induce these neuropil abnormalities remains unknown. We tested the hypothesis that oligomeric assemblies of Aβ, seen in the periphery of plaques, mediate the neurodegenerative phenotype of AD by triggering activation of the enzyme GSK-3β, which in turn appears to inhibit a transcriptional program mediated by CREB. We detect increased activity of GSK-3β after exposure to oligomeric Aβ in neurons in culture, in the brain of double transgenic APP/tau mice and in AD brains. Activation of GSK-3β, even in the absence of Aβ, is sufficient to produce a phenocopy of Aβ-induced dendritic spine loss in neurons in culture, while pharmacological inhibition of GSK-3β prevents spine loss and increases expression of CREB-target genes like BDNF. Of note, in transgenic mice GSK-3β inhibition ameliorated plaque-related neuritic changes and increased CREB-mediated gene expression. Moreover, GSK-3β inhibition robustly decreased the oligomeric Aβ load in the mouse brain. All these findings support the idea that GSK3β is aberrantly activated by the presence of Aβ, and contributes, at least in part, to the neuronal anatomical derangement associated with Aβ plaques in AD brains and to Aβ pathology itself.

Control of ticks resistant to immunization with Bm86 in cattle vaccinated with the recombinant antigen Bm95 isolated from the cattle tick, Boophilus microplus

The recombinant Bm86-containing vaccine Gavac(TM) against the cattle tick Boophilus microplus has proved its efficacy in a number of experiments, especially when combined with acaricides in an integrated manner. However, tick isolates such as the Argentinean strain A, show low susceptibility to this vaccine. In this paper we report on the isolation of the Bm95 gene from the B. microplus strain A, which was cloned and expressed in the yeast Pichia pastoris producing a glycosylated and particulated recombinant protein. This new antigen was effective against different tick strains in a pen trial, including the B. microplus strain A, resistant to vaccination with Bm86. A Bm95-based vaccine was used to protect cattle against tick infestations under production conditions, lowering the number of ticks on vaccinated animals and, therefore, reducing the frequency of acaricide treatments. The Bm95 antigen from strain A was able to protect against infestations with Bm86-sensitive and Bm86-resistant tick strains, thus suggesting that Bm95 could be a more universal antigen to protect cattle against infestations by B. microplus strains from different geographical areas.

Hepatocellular carcinoma in HIV-infected patients with chronic hepatitis C

OBJECTIVES

Chronic hepatitis C is frequently seen in HIV-positive subjects infected through needle sharing or transfusion of contaminated blood products. Progression to end-stage liver disease seems to occur faster in these patients. As the life expectancy of HIV-infected persons has dramatically improved since the introduction of highly active antiretroviral therapies, cirrhosis and eventually hepatocellular carcinoma (HCC) may be recognized at an increasing rate in patients coinfected with HIV and hepatitis C virus (HCV).

METHODS

We identified the main features of HIV-infected individuals with end-stage liver disease due to HCV infection and diagnosed with HCC in three HIV/AIDS referral centers, and compared these features to those of a control group of patients with HCV-related HCC but without HIV infection.

RESULTS

Seven HIV-infected patients were identified. Of these, six were <45 yr of age and had been intravenous drug users. The mean time between exposure to HCV and the development of HCC was estimated to be 17.8 yr. Two subjects were coinfected with hepatitis B and delta viruses, respectively. Only one individual had been diagnosed of an AIDS-defining condition before the diagnosis of HCC was made. However, all subjects had < 500 CD4+ T cells at the time of HCC diagnosis. Five died within the first 4 months of follow-up. Patients in the control group (n = 31) were significantly older (68.9 +/- 8.9 vs 42.2 +/- 10.4; p < 0.001) and the duration of HCV infection was significantly longer (28.1 +/- 10.9 vs 17.8 +/- 2.7; p < 0.05) than in those with HIV-HCV coinfection.

CONCLUSIONS

HCC seems to occur at a younger age and after a shorter period of HCV infection in subjects coinfected with HIV. Thus, treatment of CHC should be encouraged in HIV-positive patients, and in those with HCV-related cirrhosis the periodic monitoring of alpha-fetoprotein and abdominal ultrasonography should be recommended.

Design of a new multiparticulate system for potential site-specific and controlled drug delivery to the colonic region

A multiparticulate dosage form consisting of a hydrophobic core coated with a pH-dependent polymer is proposed for colonic specific delivery of drugs. Different approaches for colon-specific drug delivery have been studied over the last decade, including prodrugs, polymeric coating using pH-sensitive or bacterial degradable polymers and matrices. In this work, we present a new multiparticulate system to deliver active molecules to the colonic region, which combines pH-dependent and controlled drug release properties. This system was constituted by drug loaded cellulose acetate butyrate (CAB) microspheres coated by an enteric polymer (Eudragit(R) S). Both, CAB cores and pH-sensitive microcapsules, were prepared by the emulsion-solvent evaporation technique in an oily phase. Ondansetron (OS) and budesonide (BDS), two interesting drugs with a potentially new application for the local treatment of intestinal disorders, were efficiently microencapsulated in CAB microspheres at different polymer concentrations (6 and 8%). These hydrophobic cores (about 60 and 110 micrometer in size, respectively) were then microencapsulated with Eudragit(R) S, resulting in multinucleated structures, except in the case of BDS-CAB microspheres prepared at 8% CAB concentration, in which more mononucleated microcapsules were obtained. The in vitro drug release studies of pH-sensitive microcapsules containing the hydrophobic cores showed that no drug was released below pH 7. After that, CAB microspheres efficiently controlled the release of BDS, the release behavior being affected by the different polymer concentration used in their preparation. However, OS-CAB microspheres did not maintain their controlled-release properties once the enteric polymer dissolved. The extraction of the drug by the Eudragit(R) solvent during the second microencapsulation process was in this case the cause for the failure of the controlling release mechanism.

Large-scale production in Pichia pastoris of the recombinant vaccine Gavac against cattle tick

A gene coding for the Bm86 tick protein was recently cloned, expressed in Pichia pastoris and shown to induce an inmunological response in cattle against ticks. Moreover, the Gavac vaccine (Heber Biotec S.A., Havana, Cuba), which contains this recombinant protein, has proved to control the Boophilus microplus populations under field conditions. This paper reviews the development and large-scale production of this vaccine, the efficacy of the resulting product and the strategy followed in designing its production plant. The production plant fulfills biosafety requirements and GMP.

Vaccination against ticks (Boophilus spp.): the experience with the Bm86-based vaccine Gavac

The control of tick infestations and the transmission of tick-borne diseases remain a challenge for the cattle industry in tropical and subtropical areas of the world. Traditional control methods have been only partially successful and the parasites continue to result in significant losses for the cattle industry. Recently, vaccines containing the recombinant B. microplus gut antigen Bm86 have been developed. Our vaccine formulation (Gavac, Heber Biotec S.A., Havana, Cuba) has been registered and is commercially available in Cuba, Colombia, Dominican Republic, Brazil and Mexico. In controlled pen trials, Gavac has been effective for the control of artificial infestations of B. annulatus, B. decoloratus and chemical-sensitive and resistant B. microplus strains from Australia, Africa, America and Iran. In controlled field trials in Cuba, Brazil, Argentina and Mexico, Gavac has shown a 55-100% efficacy in the control of B. microplus infestations in grazing cattle 12-36 weeks after the first vaccination. Field trials under production conditions have been conducted in Cuba, Colombia, Brazil and Mexico in pure and cross-bred cattle herds. The application of Gavac has increased the time between acaricide treatments by an average of 32 /-21 days (P = 0.0005) resulting in important savings for the cattle industry. In Cuba, a cost-effectiveness analysis was conducted in more than 260000 animals. The cost-effectiveness analysis showed a 60% reduction in the number of acaricide treatments, together with the control of tick infestations and transmission of babesiosis, which resulted in savings of 23.4 dollars animal(-1) year (-1). These results clearly demonstrate the advantage of vaccination and support the application of Gavac for the control of Boophilus spp. infestations.

High level expression of the B. microplus Bm86 antigen in the yeast Pichia pastoris forming highly immunogenic particles for cattle

Recently, a gene coding for the Bm86 tick gut glycoprotein was cloned, expressed in Escherichia coli and shown to induce an immunological response in cattle to damage ticks engorging on these animals (Rand et al., 1989). We report here the increased expression of the Bm86 antigen from the cattle tick Boophilus microplus in the methylotrophic yeast Pichia pastoris. The recombinant protein was obtained with a purity higher than 95% by a procedure with a high yield. The conducted biochemical studies demonstrated the antigen to be glycosylated and found to form particles of around 17 to 45 nm in diameter with enhanced immunogenic properties. Ticks engorging on vaccinated cattle were significantly damaged as a result of the immune response against the recombinant antigen. This system permits the obtainment in a high yield of the tick Bm86 antigen, in a glycosylated and particulated form.

Comparison of supercritical fluid and ultrasound-assisted extraction of carotenoids and chlorophyll a from Dunaliella salina

In the work described here the extraction processes of carotenoids and chlorophylls were analysed using two extraction techniques, namely ultrasound-assisted extraction and supercritical fluid extraction, and the results are compared. The solvents used for the ultrasound-assisted extraction were N,N'-dimethylformamide and methanol and for the supercritical fluid extraction, carbon dioxide. The raw material studied was Dunaliella salina, a microalgae characterized by the high levels of carotenoids present in its cellular structure. The results indicate that the supercritical fluid extraction process is comparable to the ultrasound-assisted extraction when methanol is used as solvent. In addition, the supercritical extraction process is more selective for the recovery of carotenoids than the conventional technique since it leads to higher values for the ratio carotenoids/chlorophylls. Finally, the effects of pressure and temperature on the extraction yields of the supercritical fluid extraction process were studied.

High frequency of vitamin D deficiency in ambulatory HIV-Positive patients

Several reports have suggested an increased prevalence of osteopenia and osteoporosis in HIV-infected individuals. Vitamin D deficiency may be a risk factor for osteoporosis and bone fractures. We aimed to determine the prevalence of vitamin D insufficiency in an outpatient HIV clinic in Boston. We collected serum levels of 25-OH vitamin D and evaluated calcium and vitamin D intake in adult HIV-positive outpatients during the winter and spring of 2005. Fifty-seven subjects were enrolled. The prevalence of moderate (< or = 20 and>10 ng/ml) and severe (< or =10 ng/ml) 25-OH vitamin D deficiency was 36.8% and 10.5%, respectively. Lower vitamin D intake was significantly associated with severe 25-OH vitamin D deficiency (p=0.01). Lactose intolerance tended to be associated with severe vitamin D deficiency (p=0.08). Antiretroviral use and low daily calcium intake were significantly associated with elevated parathyroid hormone levels (p=0.01 and 0.03, respectively). Vitamin D deficiency was frequent in ambulatory HIV-positive patients. HIV-infected individuals living in areas with low exposure to ultraviolet light during winter may benefit from vitamin D supplementation.

Pairing Gap and In-Gap Excitations in Trapped Fermionic Superfluids

We consider trapped atomic Fermi gases with Feshbach-resonance enhanced interactions in pseudogap and superfluid temperatures. We calculate the spectrum of radio-frequency (or laser) excitations for transitions that transfer atoms out of the superfluid state. The spectrum displays the pairing gap and also the contribution of unpaired atoms, that is, in-gap excitations. The results support the conclusion that a superfluid, in which pairing is a manybody effect, was observed in recent experiments on radio-frequency spectroscopy of the pairing gap.

EEG activation patterns during the performance of tasks involving different components of mental calculation

In this study we demonstrate the existence of different patterns of EEG activation during the performance of 4 different tasks involving different components of mental calculation in normal subjects. The EEG was recorded in all monopolar leads of the 10/20 system using linked ear lobes as reference. Absolute and relative power were calculated in the delta (1.5-3.5 Hz), theta (3.5-7.5 Hz), alpha (7.5-12.5 Hz) and beta (12.5-19 Hz) bands. The tasks were presented randomly and the EEG segments preceding presentation of the stimulus were considered as the rest corresponding to the task requested by the stimulus. Tasks were of 4 different types, involving number comprehension, recognition of mathematical symbols, the calculation process and the spatial component. ANOVAs between the rest periods showed no differences in any band. Neither did ANOVAs between tasks. However, other variables (task minus rest), which were calculated as the differences in power between task and rest respectively, showed significant differences between tasks in the delta and beta bands in the frontal lobes. In addition, new variables were calculated as the difference between tasks, since many factors were common across several tasks. These variables correspond to the EEG change due to a specific component of mental calculation. Significant differences were obtained in delta and theta bands in right posterior areas and in the beta band in frontal areas. We concluded that the EEG differences observed during different components of mental calculation suggest the participation of different networks.

Effects of maternal stress during pregnancy on forced swimming test behavior of the offspring

It has been reported that gonadal steroids modulate brain and behavioral sex differentiation during development. Prenatal maternal restraint also alters development by affecting gonadal steroid levels in the fetus. Prenatal maternal restraint of animals decreases sex differences for sexual behavior, locomotion, aggression, etc. In recent work on animal models, we reported that, like humans, laboratory rats show sex differences in depression. From the present study, performed on Sprague-Dawley rats, we conclude that: 1) there are sex differences for depression in two different animal models (swimming-induced immobility and natatory tests); 2) there are also sex differences in open-field behavior; 3) prenatal maternal restraint decreases sex differences for depression but does not affect sex differences in open-field behavior; 4) prenatal maternal restraint affects female but not male behavior in the two depression tests used. These results suggest that: 1) sex differences reported in animal models of depression are under the control of gonadal steroids during prenatal brain development; 2) stress during early phases of development increases the risk for depression in adulthood.

Community involvement in dengue vector control: cluster randomised trial

OBJECTIVE

To assess the effectiveness of an integrated community based environmental management strategy to control Aedes aegypti, the vector of dengue, compared with a routine strategy.

DESIGN

Cluster randomised trial.

SETTING

Guantanamo, Cuba.

PARTICIPANTS

32 circumscriptions (around 2000 inhabitants each).

INTERVENTIONS

The circumscriptions were randomly allocated to control clusters (n=16) comprising routine Aedes control programme (entomological surveillance, source reduction, selective adulticiding, and health education) and to intervention clusters (n=16) comprising the routine Aedes control programme combined with a community based environmental management approach.

MAIN OUTCOME MEASURES

The primary outcome was levels of Aedes infestation: house index (number of houses positive for at least one container with immature stages of Ae aegypti per 100 inspected houses), Breteau index (number of containers positive for immature stages of Ae aegypti per 100 inspected houses), and the pupae per inhabitant statistic (number of Ae aegypti pupae per inhabitant).

RESULTS

All clusters were subjected to the intended intervention; all completed the study protocol up to February 2006 and all were included in the analysis. At baseline the Aedes infestation levels were comparable between intervention and control clusters: house index 0.25% v 0.20%, pupae per inhabitant 0.44x10(-3) v 0.29x10(-3). At the end of the intervention these indices were significantly lower in the intervention clusters: rate ratio for house indices 0.49 (95% confidence interval 0.27 to 0.88) and rate ratio for pupae per inhabitant 0.27 (0.09 to 0.76).

CONCLUSION

A community based environmental management embedded in a routine control programme was effective at reducing levels of Aedes infestation.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN88405796.

Dopamine cell degeneration induced by intraventricular administration of 6-hydroxydopamine in the rat: similarities with cell loss in parkinson's disease

In an attempt to find a convenient rat model to study cell vulnerability in Parkinson's disease, we have investigated the cell-loss profile in different midbrain dopaminergic nuclei and subnuclei of rats injected with 6-hydroxydopamine (6-OHDA) in the third ventricle. Following administration of different doses (5-1000 microgram) of 6-OHDA, motor behavior was evaluated and tyrosine hydroxylase-immunostained neurons were counted in the A8 group and different subdivisions of A9 and A10 groups. Animals developed hypokinesia, repetitive chewing movements, and catalepsia. Signs of cell degeneration were evident from the first day after injection, reaching the definitive pattern at the end of the first week. There was a similar degeneration in both brain sides, the A9 group showing the highest degree of cell-loss, followed by A8 and A10 groups. In the A9 group, the degeneration mostly affected those subgroups located in its ventral, lateral, and posterior regions. In the A10 group the degeneration mainly affected the parabrachial pigmented nucleus, the paranigral nucleus and the ventral tegmental area. This topographic pattern of degeneration is very similar to that previously described in Parkinson's disease, suggesting that this model may be a useful tool in the study of the cell vulnerability mechanisms in this neurodegenerative disorder. In addition, our results also showed that small dopaminergic neurons are more resistant to degeneration than the large ones. In some DA subgroups, the cells that contained calbindin but not calretinin were less vulnerable to the neurotoxic effect of 6-OHDA.

Sequence variations in the Boophilus microplus Bm86 locus and implications for immunoprotection in cattle vaccinated with this antigen

Cattle tick infestations constitute a major problem for the cattle industry in tropical and subtropical regions of the world. Traditional control methods have been only partially successful, hampered by the selection of chemical-resistant tick populations. The Boophilus microplus Bm86 protein was isolated from tick gut epithelial cells and shown to induce a protective response against tick infestations in vaccinated cattle. Vaccine preparations including the recombinant Bm86 are used to control cattle tick infestations in the field as an alternative measure to reduce the losses produced by this ectoparasite. The principle for the immunological control of tick infestations relies on a polyclonal antibody response against the target antigen and, therefore, should be difficult to select for tick-resistant populations. However, sequence variations in the Bm86 locus, among other factors, could affect the effectiveness of Bm86-containing vaccines. In the present study we have addressed this issue, employing data obtained with B. microplus strains from Australia, Mexico, Cuba, Argentina and Venezuela. The results showed a tendency in the inverse correlation between the efficacy of the vaccination with Bm86 and the sequence variations in the Bm86 locus (R2 = 0.7). The mutation fixation index in the Bm86 locus was calculated and shown to be between 0.02 and 0.1 amino acids per year. Possible implications of these findings for the immunoprotection of cattle against tick infestations employing the Bm86 antigen are discussed.

Contribution of dietary and newly formed arachidonic acid to human milk lipids in women eating a low-fat diet

BACKGROUND

Polyunsaturated fatty acids in milk are derived from direct intestinal absorption, endogenous synthesis, or maternal body stores. Arachidonic acid (AA) intake is frequently low in undernourished women, but milk secretion of this fatty acid is similar to that in well-nourished women.

OBJECTIVE

The objective was to evaluate the contribution of dietary and endogenously synthesized AA to its total secretion in the milk of women eating a low-fat diet.

DESIGN

Ten lactating women who habitually ate a low-fat diet (17% of energy) received 2.5 mg [(13)C]linoleic acid (LA)/kg body wt orally 5 mo postpartum. LA and AA concentrations and (13)C enrichment were measured in milk samples collected before and after the tracer application. Total lipid, LA, and AA contents were determined in diet composites. Fatty acids were assessed by gas chromatography and (13)C enrichment by isotope ratio mass spectrometry.

RESULTS

The cumulative 72-h recovery of [(13)C]LA in milk was 16.3 +/- 6.4% of the dose; only 0.01% of the label was found as [(13)C]AA. The calculated transfer of dietary LA and AA into milk was 32.8 +/- 18.0% and 11.8 +/- 6.6%, respectively. AA originating from conversion of dietary LA contributed only 1.1% to the total milk AA secreted.

CONCLUSIONS

Little milk AA originates from conversion of LA; 70% of LA and 90% of AA secreted in milk were not derived from direct intestinal absorption. Our results suggest that maternal body stores are the major source of milk LA and AA in these women.