Age dependent incorporation of 14C-DHA into rat brain and body tissues after dosing various 14C-DHA-esters

INTRODUCTION

The omega-3 fatty acid docosahexaenoic acid (DHA) accounts for 10% of fatty acids in human brain and is critical for neuronal function and brain development. Mechanisms of transport, accumulation and conservation of DHA in the brain are unclear. The objective of the study was to quantify the age dependent DHA incorporation into the brain of 2-, 4- or 10-week-old rats after a bolus dose of different DHA-esters.

METHODS

Rats were gavaged with (14)C-DHA-TAG, (14)C-DHA-PL or (14)C-DHA-TAG+PL at 2 mg DHA/kg BW. After 24h the distribution of radioactivity in body and brain regions was determined using quantitative whole body autoradiography (QWBA). Radiolabeled compounds were extracted from the brains to determine the identity of the radiolabeled compounds.

RESULTS

Accumulation of orally ingested (14)C-DHA in rat brain was less than 1% of the dose and decreased with age. Ester specific differences were seen only in 10-week-old rats, where oral (14)C-DHA-PL delivered a 2-fold higher accretion of radioactivity in the brain.

CONCLUSIONS

Less than 1% of a dietary achievable DHA dose reached the rat brain within 24h. Optimal efficacy of DHA-PL may occur in older age groups.

Preschool healthcare utilisation related to home oxygen status

OBJECTIVE

To determine, in prematurely born children who had bronchopulmonary dysplasia (BPD), if respiratory morbidity, healthcare utilisation, and cost of care during the preschool years were influenced by use of supplementary oxygen at home after discharge from the neonatal intensive care unit.

DESIGN

Observational study.

SETTING

Four tertiary neonatal intensive care units.

PATIENTS

190 children, median gestational age 27 weeks (range 22-31), 70 of whom received supplementary oxygen when discharged home.

INTERVENTIONS

Review of hospital and general practitioner records together with a parent completed respiratory questionnaire.

MAIN OUTCOME MEASURES

Healthcare utilisation, cost of care, cough, wheeze, and use of an inhaler.

RESULTS

Seventy children had supplementary oxygen at home (home oxygen group), but only one had a continuous requirement for home oxygen beyond 2 years of age. There were no significant differences in the gestational age or birth weight of the home oxygen group compared with the rest of the cohort. However, between 2 and 4 years of age inclusive, the home oxygen group had more outpatient attendances (p = 0.0021) and specialist attendances (p = 0.0023), and, for respiratory problems, required more prescriptions (p<0.0001). Their total cost of care was higher (p<0.0001). In addition, more of the home oxygen group wheezed more than once a week (p = 0.0486) and were more likely to use an inhaler (p<0.0001).

CONCLUSIONS

Children with BPD who have supplementary oxygen at home after discharge have increased respiratory morbidity and healthcare utilisation in the preschool years.

Health care utilisation of prematurely born, preschool children related to hospitalisation for RSV infection

BACKGROUND

In prematurely born infants with chronic lung disease (CLD), RSV hospitalisation is associated with increased health service utilisation and costs in the first two years after birth.

AIMS

To determine whether RSV hospitalisation in the first two years was associated with chronic respiratory morbidity during the preschool years in prematurely born children who had had CLD.

METHODS

Retrospective review of readmissions, outpatient attendances, and community care in years 2-4 and, at age 5 years, assessment of the children's respiratory status and their health related quality of life. Comparison was made of the results of children who had had at least one hospitalisation in the first two years after birth for RSV infection (RSV group) to those of the rest of the cohort. Participants were 190 of an original cohort of 235 infants with CLD and a median gestational age 27 (range 22-33) weeks.

RESULTS

The 33 children in the RSV group, compared to the rest of the cohort, had a greater duration of hospital stay and more outpatient appointments. The RSV group had required more prescriptions for all treatments and respiratory medications, and more had used an inhaler. The cost of care of the RSV group was higher (median 2630 pounds sterling [4000 Euros, US4800 dollars], range 124-18,091 pounds sterling versus 1360 pounds sterling [2500 Euros, US3000 dollars], range 5-18 929 pounds sterling ) and their health related quality of life was lower.

CONCLUSION

In prematurely born children who had developed CLD, RSV hospitalisation in the first two years was associated with chronic respiratory morbidity and increased cost of care.

Parasite genome initiatives

During 1993-1994, scientists from developing and developed countries planned and initiated a number of parasite genome projects and several consortiums for the mapping and sequencing of these medium-sized genomes were established, often based on already ongoing scientific collaborations. Financial and other support came from WHO/TDR, Wellcome Trust and other funding agencies. Thus, the genomes of Plasmodium falciparum, Schistosoma mansoni, Trypanosoma cruzi, Leishmania major, Trypanosoma brucei, Brugia malayi and other pathogenic nematodes are now under study. From an initial phase of network formation, mapping efforts and resource building (EST, GSS, phage, cosmid, BAC and YAC library constructions), sequencing was initiated in gene discovery projects but soon also on a small chromosome, and now on a fully fledged genome scale. Proteomics, functional analysis, genetic manipulation and microarray analysis are ongoing to different degrees in the respective genome initiatives, and as the funding for the whole genome sequencing becomes secured, most of the participating laboratories, apart from larger sequencing centres, become oriented to post-genomics. Bioinformatics networks are being expanded, including in developing countries, for data mining, annotation and in-depth analysis.

Spontaneous dimerization and leucine-zipper induced activation of the recombinant catalytic domain of a new adenylyl cyclase of Trypanosoma brucei, GRESAG4.4B

In this study, we describe the isolation and characterization of a new adenylyl cyclase from Trypanosoma brucei and its activation by dimerization of the catalytic domain. In agreement with the current nomenclature of trypanosomal adenylyl cyclases, this new gene is termed GRESAG4.4B. The complete ORF of the GRESAG4.4B gene encodes a protein of 1291 amino acids. Its predicted protein structure is consistent with the structure of other trypanosomal cyclases, and with the cyclases of L. donovani. GRESAG 4.4B is constitutively expressed during the life cycle of trypanosomes. GRESAG4.4B is a member of a gene family, which contains at least six members, which are all clustered on chromosome IV. The catalytic domain of GRESAG4.4B is able to dimerize spontaneously. However, these spontaneously formed, stable dimers only show minimal enzymatic activity. The addition of a leucine zipper (LZ) derived from the S. cerevisiae GCN 4 gene to the N-terminus of the catalytic domain of GRESAG4.4B strongly activated its enzymatic activity. The LZ appears to enforce a distinct conformation of the dimer, which leads to an increased enzymatic activity, and thus may mimic the effect of ligand-induced dimerization of adenylyl cyclase in vivo.

Lack of definitive severe mitochondrial signs and symptoms among deceased HIV-uninfected and HIV-indeterminate children < or = 5 years of age, Pediatric Spectrum of HIV Disease project (PSD), USA

BACKGROUND

In response to recent reports of mitochondrial dysfunction in HIV-uninfected infants exposed to antiretroviral (ARV) prophylaxis, the Perinatal Safety Review Working Group reviewed deaths in five large HIV-exposed perinatal cohorts in the United States to determine if similar cases of severe mitochondrial toxicity could be detected. We describe the results of this review for the PSD cohort.

METHODS

Hospitalization, clinic and death records for deceased HIV-uninfected and HIV-indeterminate children who were less than 5 years of age were reviewed. Standard definitions were used to classify HIV infection status and the likelihood that signs and symptoms were related to mitochondrial dysfunction. Children were classified as having signs and symptoms that were considered (1) unrelated, (2) unlikely, (3) consistent with, or (4) likely related to mitochondrial disease. SIDS deaths were put into a separate category.

RESULTS

8,465 of 13,125 HIV-exposed children were either HIV-uninfected or HIV-indeterminate. Among the 84 deaths in the subgroup of 8,465 children, 9 were considered in Class 2 (unlikely), 4 were considered in Class 3 (consistent with), and none were considered in Class 4 (likely). 97% of those children who received ARV prophylaxis received zidovudine alone. None of the HIV-uninfected deaths were classified in 2, 3, or 4; and only one of these was exposed to ARV prophylaxis. Among the 3 HIV-indeterminate children who were classified in 3 (consistent with), 2 had no or unknown ARV exposure before 1994 when use of ZDV prophylaxis became the standard of care. Both HIV-uninfected and HIV-indeterminate children with ARV exposure or unknown exposure had lower mortality rates than children without ARV exposure.

CONCLUSION

Monoprophylaxis with ZDV was not associated with higher death rates in the cohort of 8,465 children or with any findings likely consistent with mitochondrial dysfunction among the 85 deaths. Ongoing monitoring of drug safety in large multi-site prospective cohort studies of HIV-exposed children is essential in the era of highly active antiretroviral therapy.

Survival in children with perinatal HIV infection and very low CD4 lymphocyte counts

OBJECTIVES

To evaluate clinical conditions associated with mortality in HIV-infected children with CD4+ counts <100 cells/microl.

METHODS

The Pediatric Spectrum of HIV Disease Project is a longitudinal medical record review study with eight study sites in the United States, which have been enrolling children since 1989. Survival time from baseline very low CD4 count (<100 cells/microl) to death was estimated using the Kaplan-Meier method. Cox proportional hazards models were used to evaluate the effect of clinical variables on mortality.

RESULTS

Of 522 children (>/=1 year of age) with serial CD4+ T-lymphocyte measurements, the median age at the first very low CD4 count was 4.8 years. The estimated median survival following the first very low CD4 count was 36 months. The following factors present at the first very low CD4 count were independently associated with a higher risk of death: younger age, weight-for-age >2 standard deviations below the mean, and previously diagnosed AIDS. The subsequent development of cytomegalovirus (CMV)-associated disease, Mycobacterium avium intracellulare (MAI) infection, wasting syndrome, or esophageal candidiasis was also independently associated with a higher risk of death.

CONCLUSION

Survival in HIV-infected children with very low CD4 counts before introduction of highly active antiretroviral therapy was highly variable. Poor nutritional status and the development of CMV disease or MAI infection were associated with the shortest survival times.

Analysis of ploidy (in megabase chromosomes) in Trypanosoma brucei after genetic exchange

The megabase chromosomes of Trypanosoma brucei are normally diploid, but the extent to which this ploidy is maintained when parasites undergo genetic exchange is not known. To investigate this issue, a panel of 30 recombinant clones resulting from the co-transmission through tsetse flies of three different parental T. brucei lines in all pair-wise combinations (STIB 247, STIB 386 and TREU 927/4) were examined. These clones are products of 28 different mating events; four of them result from self-fertilisation and the others are F1 hybrids. DNA contents of the three parental lines were determined by flow cytometry and shown to differ only slightly with DNA content increasing in the order 927/4 < 247 < 386. Flow cytometry of the recombinant clones indicated DNA contents were similar to the parents in 28 clones and raised approximately 1.5 times the parental values in only two. The two F1 hybrid progeny with raised DNA contents were shown by marker analysis to be trisomic for seven independent loci indicating that they were probably triploid whereas progeny with DNA contents similar to parental values inherited a single allele from each parent for four independent loci indicating that they were diploid.

Health care providers' perspectives on patient delay for seeking care for symptoms of acute myocardial infarction

To inform intervention development in a multisite randomized community trial, the Rapid Early Action for Coronary Treatment (REACT) project formative research was undertaken for the purpose of investigating the knowledge, beliefs, perceptions, and usual practice of health care professionals. A total of 24 key informant interviews of cardiologists and emergency physicians and 15 focus groups (91 participants) were conducted in five major geographic regions: Northeast, Northwest, Southeast, Southwest, and Midwest. Transcript analyses revealed that clinicians are somewhat unaware of the empirical evidence related to the problem of patient delay, are concerned about the practice constraints they face, and would benefit from concrete suggestions about how to improve patient education and encourage fast action. Findings provide guidance for selection of educational strategies and messages for health providers as well as patients and the public.

Transcription of 'inactive' expression sites in African trypanosomes leads to expression of multiple transferrin receptor RNAs in bloodstream forms

African trypanosomes express a heterodimeric transferrin receptor that mediates iron uptake from the host bloodstream. The genes encoding the receptor, ESAG6 and ESAG7, are found at the beginning of VSG expression sites: these are telomeric, polycistronic transcription units that each terminate with a gene encoding a trypanosome variant surface glycoprotein, VSG. Approximately 20 of these VSG expression sites are found in the trypanosome genome, but only one VSG is expressed at a time. The conventional view is that one expression site promoter is extremely active whereas the others are either inactive or show very low, poorly processive activity, and that all transferrin receptor molecules are encoded by the active expression site. The 3'-end of the ESAG6 gene is more than 5 kb from the promoter. We show here that 20% of ESAG6 mRNA originates from the 'inactive' expression sites. We suggest that many expression site promoters in trypanosomes show low-level activity throughout the life cycle, and that transcription proceeds for at least 5 kb. This suggests a simplified model of VSG expression site control, whereby the only regulated event is the strong activation of a single expression site promoter in bloodstream forms.

Analysis of the genomic organisation of a small chromosome of Leishmania braziliensis M2903 reveals two genes encoding GTP-binding proteins, one of which belongs to a new G-protein family and is an antigen

Leishmania braziliensis M2903 contains a highly amplified small chromosome. This work is aimed at resolving its structural organization and determining whether this unusual chromosome contains specific genes encoding proteins with important functions in disease pathology or drug resistance. Our results show that the M2903 250-kb small chromosome contains LD1 sequences and has an inverted repeat structure. The LD1 sequences and two cDNAs (cDNA2 and cDNA53) were mapped on a cosmid contig, and the two cDNAs and the corresponding genomic fragments from the small chromosome were sequenced. The gene encoding cDNA2 predicts a putative GTP-binding protein with homology to other GTP-binding proteins only in the G-1 domain region; however, four other conserved motifs can be recognized. Sequence similarity to cDNA53 is located in at least five chromosomes, and its small chromosome copy is a pseudogene. An open reading frame downstream of the cDNA53 pseudogene predicts another GTP-binding protein that belongs to a new G-protein family with an unusual conserved GTP-binding domain and a newly characterized conserved sequence motif. A portion of this GTP-binding protein gene was studied previously in L. aethiopica as a recombinant antigen that reacts with human antibodies.

Absence of neurogenesis of adult rat dorsal root ganglion cells

Recently, an age-related increase in the number of dorsal root ganglion (DRG) cells was reported in adult rats. This suggests neurogenesis of adult primary afferent neurons, which would be an extremely important phenomenon if it occurred. Other evidence is not compatible with this idea, however, so the issue is not settled. The primary point of contention concerns the counts of DRG cells in relation to age. In our opinion, these disagreements arise, at least in part, because different counting methods give different results for the same material. Thus, any method for determining DRG cell numbers should be calibrated. We previously calibrated some of the common methods used to count DRG cells and found that an empirical method gave accurate cell counts. In the present study, we have used this method and asked whether an age-related increase in the number of lumbar DRG cells can be demonstrated in adult rats. Our data indicate that DRG cell numbers remain essentially constant from 3 to 22 months of age. Most ancillary evidence is consistent with the hypothesis that mammalian DRG cell numbers do not change during adult life. Thus, we feel that the evidence does not support the hypothesis that there is neurogenesis of adult rat primary afferent neurons.

Increased protein turnover despite normal energy metabolism and responses to feeding in patients with lung cancer

We have examined the responses of energy and protein metabolism to nutrient intake in nine patients with lung carcinoma, of whom none were cachexic and only one had distant metastases, compared with nine control patients for elective aneurysm surgery, who were comparable in terms of age, body mass index, and smoking habits. Whole-body protein turnover and leucine oxidation were assessed by primed continuous infusion of L-[13C]leucine. Indirect calorimetry was used to determine energy expenditure and rates of carbohydrate and fat utilization. Lean body mass (LBM) was estimated from dilution of deuterium oxide. Measurements were made over an 8-h period, including 4 h postabsorptive followed by 4 h of feeding, during which small hourly meals were consumed. In the post-absorptive state, the rate of incorporation of leucine into protein was higher in the cancer group (mean +/- SD, cancer versus control: 102 +/- 21 versus 86 +/- 8 mumol/kg LBM/h, P less than 0.05), as was the release of leucine by protein degradation (126 +/- 19 versus 110 +/- 10 mumol/kg LBM/h, P less than 0.01), but there was no difference in rates of leucine oxidation (27 +/- 6 versus 27 +/- 5 mumol/kg LBM/h) or leucine balance (-25 +/- 7 versus -24 +/- 4 mumol/kg LBM/h). There were no differences between the cancer and control groups with respect to either resting energy expenditure (37.3 +/- 3.5 versus 35.2 +/- 3.8 kcal LBM/day) or the postabsorptive pattern of nutrient utilization (61 +/- 13% fat, 26 +/- 10% carbohydrate, and 13 +/- 2% protein versus 65 +/- 7%, 21 +/- 7%, and 14 +/- 2%, respectively). During feeding, leucine oxidation rose relative to the postabsorptive state, incorporation into protein remained the same, and release by protein degradation fell. Incorporation (106 +/- 20 versus 89 +/- 7 mumol/kg LBM/h, P less than 0.05) and release (59 +/- 12 versus 42 +/- 14 mumol/kg LBM/h, P less than 0.02) remained higher in the cancer group than in controls, but leucine oxidation (43 +/- 15 versus 43 +/- 12 mumol/kg LBM/h) and leucine balance (+48 +/- 10 versus +47 +/- 12 mumol/kg LBM/h) were the same. Energy expenditure during feeding increased to 43.8 +/- 5.1 versus 43.2 +/- 4.2 kcal/kg LBM/day, derived from 32 +/- 11% fat, 52 +/- 9% carbohydrate, and 16 +/- 5% protein in cancer patients and 36 +/- 7%, 48 +/- 8%, and 16 +/- 4%, respectively, in controls.(ABSTRACT TRUNCATED AT 400 WORDS)

Preservation of sensory cells by placing stumps of transected nerve in an impermeable tube

It is known that transection of a major peripheral nerve results in the loss of a significant number of sensory cells whose axons travel in that nerve. The present study confirms this observation and shows that placement of the stump of such a transected nerve into an impermeable tube prevents this loss. We further show that this preservation does not depend on axonal regeneration. Further experiments to define the phenomenon and to obtain beginning insight into mechanisms are discussed. If these findings can be generalized to humans, they may have clinical significance.

The role of degradation in the acute control of protein balance in adult man: failure of feeding to stimulate protein synthesis as assessed by L-[1-13C]leucin infusion

The effect of feeding on whole-body protein turnover was measured in six healthy volunteers using the essential amino acid, L-[1-13C]leucine, as a tracer for protein metabolism. Varied lengths of periods of feeding and isotope infusion produced different apparent responses to feeding. When parameters of protein turnover were estimated from 8-hour infusions, the change from post-absorptive in the first four hours to mixed feeding during the final four hours was found to produce positive leucine balance by decreasing degradation from 89.5 +/- 5.0 to 31.7 +/- 7.3 mumol leucine/kg/h (P less than .001), with no apparent change in synthesis. By contrast, when tracer was infused for 24 hours with 12 hours of feeding followed by 12 hours of fasting, the estimate of protein synthesis during feeding was 35% higher than during fasting (P less than .01). However, when tracer infusion during the 12-hour feeding/12-hour fasting protocol was limited to the last four hours of each nutritional period, the estimates of fed and fasted protein synthesis showed no significant difference, 71.3 +/- 6.5 and 66.2 +/- 5.6 respectively, while the calculated rate of protein degradation was 43% lower during feeding (P less than .002). As relatively higher levels of enrichment in plasma leucine were detected in comparable nutritional states following longer infusions, the possibility of significant recycling of label was investigated. Residual tracer was still detectable in both breath and plasma 12 hours after cessation of a 12-hour tracer infusion, supporting the conclusion that significant errors in estimates of protein turnover due to recycling of label arise with prolonged infusions.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbohydrate oxidation: do we eat ourselves or our food?

In post-absorptive man, energy is derived solely from oxidation of body stores, mainly by oxidation of fat rather than glycogen. Eating changes this pattern so that carbohydrate (CHO) oxidation predominates. If during feeding energy intake exceeds energy expenditure, the energy needs of the whole body can in theory be met entirely from the diet. However, it is not clear whether the CHO utilised in the fed state does come directly from the absorbed diet, or whether some continues to be removed from body stores.

Pulmonary Tuberculosis as shown by X-rays, but without Physical Signs

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The King George Military Hospital-Radiographic Department

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Demonstration of "Duralumin."

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A Discussion on the Use of X-rays in the Diagnosis of Pulmonary Tuberculosis: X-Rays in the Early Diagnosis of Pulmonary Tuberculosis

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