A general swimming response in exhausted obligate swimming fish.

Marine organisms normally swim at elevated speeds relative to cruising speeds only during strenuous activity, such as predation or escape. We measured swimming speeds of 29 ram ventilating sharks from 10 species and of three Atlantic bluefin tunas immediately after exhaustive exercise (fighting a capture by hook-and-line) and unexpectedly found all individuals exhibited a uniform mechanical response, with swimming speed initially two times higher than the cruising speeds reached approximately 6 h later. We hypothesized that elevated swimming behaviour is a means to increase energetic demand and drive the removal of lactate accumulated during capture via oxidation. To explore this hypothesis, we estimated the mechanical work that must have been spent by an animal to elevate its swim speed and then showed that the amount of lactate that could have been oxidized to fuel it comprises a significant portion of the amount of lactate normally observed in fishes after exhaustive exercise. An estimate for the full energetic cost of the catch-and-release event ensued.

HIV prevention strategies and risk of infection: a model-based analysis.

Risk populations for HIV infections tend to neglect condom use, making alternative preventive approaches necessary. Accordingly, we modelled the risk of sexual HIV transmission for condom use vs. use of rapid diagnostic test (RDT) systems with subsequent exclusion of potential sexual partners with a correctly or falsely positive test from unprotected sex with and without the use of HIV pre-exposure prophylaxis (PrEP) in a bio-statistical approach. We combined a previously described model of transmission risk for HIV-exposed individuals with a newly suggested model of risk of HIV exposure for sexually active HIV-negative individuals. The model was adapted for several stages of infection and different strategies of HIV infection prevention.HIV prevention with RDTs can reduce the transmission risk by up to 97% compared with having sex without any prevention and up to 80% compared with condom use. Nevertheless, RDT-based prevention strategies demonstrate a lack of protection in several stages of infection; in particular, RNA-based RDT systems may fail under treatment. RDT-based pre-screening of potential sex partners prior to unprotected sexual contacts substantially reduces HIV transmission risk. Combination of different prevention strategies is advisable for high-risk groups.

Polymorphism of X-linked CD40 ligand gene associated with pulmonary tuberculosis in the Han Chinese population.

Among those developing tuberculosis (TB) after exposure to Mycobacterium tuberculosis, approximately 70% are males. Host genetic variation, particularly immune-related genes on the X chromosome, may contribute to sex-specific differences in TB incidences. To study whether X-linked gene variation is associated with sex-specific presentation of pulmonary TB (pTB), three single-nucleotide polymorphisms (SNPs) of the TLR8, CD40LG and IRAK1 genes on the X chromosome were genotyped in 923 patients and 1033 healthy individuals of the Han Chinese population. Frequencies of the variants were analyzed independently as well as in their combinations. CD40LG rs3092923 and its combined effects with the other two SNPs were associated with an increased risk of pTB only in males. In males, the rs3092923 genotype C/(-) conferred relative protection (odds ratio (OR): 0.52, 95% confidence interval (CI): 0.35-0.78, Pcorr.=0.0045) and the combined effects of three SNPs increased gradually as the number of risk alleles increased (OR: 2.58, 2.83 and 2.96 for one, two and three risk alleles, respectively). For the remaining SNPs, significance was obtained only for the AA genotype of IRAK1 rs3027898 in the combined and female-only analysis. Our results indicate a role of a CD40LG variant and its combined effects with distinct TLR8 and IRAK1 variants in susceptibility to pTB in males.

National health insurance coverage and socio-economic status in a rural district of Ghana.

OBJECTIVE: To explore the association between socio-economic status (SES) and health insurance subscription to the Ghanaian National Health Insurance Scheme (NHIS) of residents of the Asante Akim North district of the Ashanti Region, Ghana. METHODS: In the course of a community survey, data on asset variables (e.g. electricity, housing conditions and other variables) and on NHIS subscription were collected on the household level in 99 villages. Using principal components analysis, households were classified into three categories of SES (20% high, 40% middle and 40% low SES). Odds ratios of NHIS subscription were calculated for all SES categories, using the low category as the reference group and adjusting for travelling time to health facilities by public transport. RESULTS: Of the 7223 households surveyed, 38% subscribed to the NHIS, of these 21% were low, 43% middle and 60% high SES households. SES was significantly associated with NHIS subscription (high SES: OR 4.9, 95% CI 4.3-5.7; middle SES: OR 2.5, 95% CI 2.2-2.9; low SES: OR 1, reference group). CONCLUSION: Four years after its introduction, the NHIS has reached subscription rates of 38% in the district surveyed. However, to achieve the aim of assuring universal access to health care facilities for all residents of Ghana, in particular for individuals living under socio-economic constraints, increasing subscription rates are necessary.

A structural variant of the human interferon-gamma gene.

The first structural IFNG variant, G54D (c.287G>A, ss105106770), located in the second exon, was identified.

Effects of food type on diel behaviours of common carp Cyprinus carpio in simulated aquaculture pond conditions.

In order to better understand behaviour patterns of common carp Cyprinus carpio in aquaculture ponds, their diel grazing, swimming, resting and schooling behaviours were observed in six 1 m(2) tanks under simulated pond conditions. Each tank was fertilized to stimulate natural food production before starting experiments, and then stocked with three C. carpio. Fish behaviours were compared among three treatments: (1) tanks with plankton only, (2) tanks with plankton and benthic macroinvertebrates and (3) tanks with plankton, benthic macroinvertebrates and artificial feed. Overall C. carpio grazed more frequently during daytime than at night and exhibited the reverse pattern for non-feeding swimming behaviour. A significant negative relationship (r(2) = 0.99, P < 0.01, n = 48) was observed between total per cent grazing time and total per cent swimming time. Fish dispersed to graze individually during daytime but schooled at night and did not display any agonistic behaviours. Diel variations in the vertical swimming behaviour of C. carpio were related to food types available. In tanks containing plankton only, fish grazed in the water column, whereas when benthic macroinvertebrates were present, they spent more time near the tank bottom. Resting behaviour was only seen in tanks with artificial feed and even then was rare (2-5% of total time). Results suggest that C. carpio growth and feed utilization efficiency in semi-intensive aquaculture systems could be optimized by using a combination of plankton, benthic macroinvertebrates and artificial feed, and feeding fish twice per day (at c. 0730 and c. 1630 hours).

No associations of human pulmonary tuberculosis with Sp110 variants.

BACKGROUND: After a recent report on the role of the Ipr1 gene in mediating innate immunity in a mouse model of Mycobacterium tuberculosis infection, the human Ipr1 homologue, Sp110, was considered a promising candidate for an association study in human tuberculosis. METHODS: In a sample of >1000 sputum positive, HIV negative West African patients with pulmonary tuberculosis and >1000 exposed, apparently healthy controls, we have genotyped 21 Sp110 gene variants that were either available from public databases, including HapMap data, or identified by DNA re-sequencing. RESULTS: No significant differences in the frequencies of any of the 21 variants were observed between patients and controls. This applied also for HapMap tagging variants and the corresponding haplotypes, when including sliding window analyses with three adjacent variants, and when stratifying controls for positivity and negativity according to the results of intradermal tuberculin (purified protein derivative, PPD) skin tests. DNA re-sequencing revealed 13 novel Sp110 variants in the 5'-UTR, exons, and adjacent intronic regions. CONCLUSIONS: Based on the results obtained in this case-control study, the hypothesis that Sp110 variants and haplotypes might be associated with distinct phenotypes of human M tuberculosis infection is doubtful.

Pre-treatment with chloroquine and parasite chloroquine resistance in Ghanaian children with severe malaria.

BACKGROUND: Self-medication with anti-malarial drugs is widespread, and chloroquine (CQ) resistance is increasing. The effect of these factors on the incidence and presentation of severe malaria is uncertain. AIM: To investigate subtype of severe malaria, duration of illness, previous CQ treatment and prevalence of Plasmodium falciparum CQ-resistance markers among children presenting with severe malaria to a teaching hospital in Ghana. DESIGN: Prospective clinical study. METHODS: Consecutive patients (n = 189) presenting with severe malaria were examined clinically, and blood was taken for routine haematology and malaria films. Plasma and blood cells were stored and subsequently analysed by ELISA for CQ levels (n = 168) and by PCR and restriction digest for P. falciparum chloroquine resistance transporter gene (pfcrt) mutations (n = 139). RESULTS: Of 47 presenting with cerebral malaria, 21 had severe anaemia and 13 respiratory distress (RDS). Twenty-nine had prostration or RDS alone, 41 severe anaemia with prostration or RDS, and 72 severe anaemia not associated with coma, prostration or RDS. Of the patients studied, 77% had CQ in their plasma, and 88% were carrying P. falciparum with a CQ-resistance genotype. Significant associations were found (i) between the CQ-resistance genotype of parasites and plasma CQ levels, (ii) between the presence of CQ in plasma and the reported duration of illness, and (iii) between the reported duration of illness and the occurrence of severe but otherwise uncomplicated anaemia. DISCUSSION: There was extensive prior CQ use in our patients presenting with severe malaria, and a high prevalence of parasites with the CQ-resistance genotype. CQ resistance in P. falciparum may contribute to the development of severe but otherwise uncomplicated anaemia in this setting.

Polymorphisms of transporter associated with antigen processing type 1 (TAP1), proteasome subunit beta type 9 (PSMB9) and their common promoter in African children with different manifestations of malaria.

The distribution of gene variants of the antigen processing proteins transporter associated with antigen processing type 1 (TAP1) and proteasome subunit beta type 9 (PSMB9) and of their shared bidirectional promoter was assessed in children with either mild or severe malaria. The genetic study was performed on samples collected during a longitudinal study on malariometric indices in an area hyperendemic for Plasmodium falciparum malaria in Gabon. The allele frequencies of the genes did not differ between the mild and the severe malaria groups. The distributions of alleles among children with distinct phenotypes of severe malaria were similar. A negative association of hypoglycaemia with the PSMB9 promoter variant PSMB9-R was found (odds ratio 0.01; chi2=12.1; P<0.0005; Pc<0.03). The promoter allele TAP1-446G was associated with hyperparasitaemia and absence of hypoglycaemia. TAP1, PSMB9, and TAP1/PSMB9 promoter alleles were in strong linkage disequilibrium. DNA sequencing of the TAP1/PSMB9 promoter region revealed a previously unrecognized single nucleotide polymorphism 455 bp upstream of the TAP1 transcription start site.

The species Mycobacterium africanum in the light of new molecular markers.

The findings of recent studies addressing the molecular characteristics of Mycobacterium tuberculosis complex isolates have initiated a discussion on the classification of M. africanum, especially of those isolates originating from East Africa (cluster F, subtype II) and displaying phenotypic and biochemical characteristics more similar to those of M. tuberculosis. To further address this question, we analyzed a representative collection of 63 M. tuberculosis complex strains comprising 30 M. africanum subtype I strains, 20 M. africanum subtype II strains, 10 randomly chosen M. tuberculosis isolates, and type strains of M. tuberculosis, M. bovis, and M. africanum for the following biochemical and molecular characteristics: single-nucleotide polymorphisms (SNPs) in gyrB and narGHJI and the presence or absence of RD1, RD9, and RD12. For all molecular markers analyzed, subtype II strains were identical to the M. tuberculosis strains tested. In contrast, the subtype I strains as well as the M. africanum type strain showed unique combinations of SNPs in gyrB and genomic deletions (the absence of RD9 and the presence of RD12), which proves their independence from M. tuberculosis and M. bovis. Accordingly, all subtype I strains displayed main biochemical characteristics included in the original species description of M. africanum. We conclude that the isolates from West Africa were proved to be M. africanum with respect to the phenotypic and genetic markers analyzed, while the isolates from East Africa must be regarded as phenotypic variants of M. tuberculosis (genotype Uganda). We propose the addition of the molecular characteristics defined here to the species description of M. africanum, which will allow clearer species differentiation in the future.

[Non-invasive screening for GJB2 mutations in buccal smears for the diagnosis of inherited hearing impairment]. / Screening auf GJB2-Mutationen mit Wangenabstrichmaterial zur nicht-invasiven Diagnostik genetisch bedingter Innenohrschwerhörigkeit.

BACKGROUND: Approximately 1 out of 1000 children is affected by severe or profound hearing impairment at birth. In the last years it has been shown that more than 50 % of inherited prelingual, sensorineural hearing impairment may be attributed to genetic defects. Most commonly, the GJB2 gene (chromosome 13q11) that encodes connexin 26 (Cx26) is affected. Cx26 is crucial for the formation of gap junctions which play an important role in the intercellular exchange of electrolytes. A variety of autosomal recessive GJB2 mutations associated with inherited hearing impairment has meanwhile been identified. The most common GJB2 mutation in Caucasian populations, 35delG accounts for the majority of cases and has a carrier frequency of more than 2.5 %. Other distinct mutations account for hearing impairment in other parts of the world. MATERIAL AND METHODS: We examined in 59 Caucasian and Ghanaian individuals whether DNA recovered from buccal smears was appropriate for genetic testing by polymerase-chain reaction (PCR) based DNA-sequencing. RESULTS: Buccal smears could be taken conveniently in all cases, even from small babies. In 53 out of 59 samples the material recovered from buccal smears could be subjected to PCR of the second exon of the GJB2 gene and subsequent DNA-sequencing. GJB2 mutations were identified in 34 patients. 13 Caucasian individuals exhibited the most common mutation 35delG. In addition, four cases of the rare W24X and each one heterozygous case of the V153I- and the L90P mutation were found. In two African individuals the 35insG mutation was detected. All other African patients had mutations exclusively identified in Ghana so far with the exception of R143W. R143W accounts for most cases of profound deafness in Ghana and has been identified in low frequencies in other ethnic groups as well. CONCLUSION: Screening for GJB2 mutations in DNA recovered from buccal smears of individuals with inherited hearing impairment offers an easy, non-invasive method for early diagnosis and a basis of genetic counselling.

TNFalpha-308A associated with shorter intervals of Plasmodium falciparum reinfections.

A mutation at position -308 of the tumor necrosis factor alpha (TNF-308A) gene promoter has previously been associated with particular manifestations of infectious and non-infectious diseases. In a longitudinal study on malariological parameters in Gabon, TNF promoter variants of 98 children initially presenting with severe Plasmodium falciparum malaria, followed by a total of 504 reinfection events within 52 months, and 100 children initially presenting with mild malaria followed by a total of 342 reinfections were analyzed. Symptomatic P. falciparum reinfections occurred more quickly (median 11 weeks) in carriers of the TNF-308A allele, with severe malaria at enrollment, compared to carriers of other TNF promoter variants (median 16 weeks). The results show that this particular TNF promoter allele increases the risk of reinfection with the malaria parasite P. falciparum.

Spleen size determined by ultrasound in patients with sickle cell trait, HbAC trait and glucose-6-phosphate-dehydrogenase deficiency in a malaria hyperendemic area (Ashanti Region, Ghana).

The occurrence of enlarged spleens and its age distribution has long been used as a crude measure to estimate malaria endemicity in cross-sectional surveys. Spleen size, however, is influenced by several variables that should be considered if they are observed in a population under study. We hypothesized that spleen indices are dependent on distinct red blood cell polymorphisms. Accordingly, we expected a lower prevalence of splenomegaly among patients with the sickle-cell trait (HbAS), HbAC trait and G6PD deficiency than in patients without red cell disorders, possibly due to the lower incidence of malaria attacks in these individuals. In our survey, however, spleen rates and sizes did not differ significantly between HbAA-, HbAS- and HbAC-positive individuals. Furthermore, enlargement of spleens was found at similar frequencies in persons with and without glucose-6-phosphate-dehydrogenase (G6PD)-deficiency (G6PD-A(-)).

Evidence for a reduced effect of chloroquine against Plasmodium falciparum in alpha-thalassaemic children.

Alpha-thalassaemia is common in malaria-endemic regions and is considered to confer protection from clinical disease due to infection with Plasmodium falciparum. In vitro, sensitivity to chloroquine (CQ) of P. falciparum infecting alpha-thalassaemic erythrocytes is reduced. We examined, in a cross-sectional study of 405 Nigerian children, associations between alpha-globin genotypes, blood concentrations of CQ, and P. falciparum parasitaemia. Of the children, 44% were alpha+-thalassaemic (36.8% heterozygous, 7.6% homozygous). CQ in blood and P. falciparum-infection were observed in 52 and 80%, respectively. CQ was more frequently found in homozygous alpha+-thalassaemic (71%) than in non-thalassaemic children (50%; odds ratio, 2.42; 95% confidence interval, 1.01-5.8). Among children with CQ in blood and despite similar drug concentrations, alpha+-thalassaemic individuals had fewer infections below the threshold of microscopy which were detectable by PCR only, and they had a higher prevalence of elevated parasitaemia than non-thalassaemic children. No such differences were discernible among drug-free children. CQ displays a lowered efficacy in the suppression of P. falciparum parasitaemia in alpha+-thalassaemic children; hence protection against malaria due to alpha+-thalassaemia may be obscured in areas of intense CQ usage. Moreover, alpha+-thalassaemia may contribute to the expansion of CQ resistance.

HLA-DQB1*0501-restricted Th1 type immune responses to Plasmodium falciparum liver stage antigen 1 protect against malaria anemia and reinfections.

Protective immunity against Plasmodium falciparum requires constant exposure to the pathogen. T cell-mediated immune responses are induced by T cell epitopes of pre-erythrocytic stage antigens of P. falciparum and involve HLA-restricted CD4 and CD8 cells. Cytotoxic T cell responses to a conserved epitope of P. falciparum liver stage antigen (LSA) type 1 are restricted by the HLA class I allele Bw53. The role of HLA class II alleles in mediating cellular responses against P. falciparum LSA-1 has not yet been demonstrated. In a longitudinal study performed for >4 years, associations were found between the HLA class II allele DQB1*0501 and protection from malaria anemia and malarial reinfections in Gabonese children. Children carrying DQB1*0501 had a higher frequency of interferon-gamma responses to LSA-1 T cell epitopes, compared with noncarriers.

Impact of subpatent multi-species and multi-clonal plasmodial infections on anaemia in children from Nigeria.

Childhood anaemia in sub-Saharan Africa is often caused by Plasmodium falciparum malaria. The influence of subpatent, multi-species and polyclonal infections with malaria parasites on haematological parameters was assessed in 1996/97 in clinically healthy children in Nigeria. Of the 228 children studied, 64% were anaemic by the WHO age-dependent criteria. A univariate analysis of risk factors indicated that the prevalence of anaemia was dependent on the number of Plasmodium species detected by species-specific PCR (P < 0.0001). Furthermore, the prevalence of anaemia increased gradually with the complexity (P < 0.003) as well as with the extent of P. falciparum parasitaemia (P < 0.0001). A logistic regression analysis revealed that individuals with an enlarged spleen tended to be anaemic. The number of Plasmodium species by which an individual was infected was independently associated with anaemia (P < 0.03). ANOVA revealed that the age-corrected values for haemoglobin (Hb) and red blood cells (RBCs) were mainly influenced by the occurrence of mixed infections. Haematological parameters were also influenced by the number of different P. falciparum clones by which an individual was infected. Hb levels and RBC counts were further diminished by additional infections with P. malariae and/or P. ovale. However, the effect of multi-species infections on haematological parameters exceeded that of multi-clonal infections.

Plasma interleukin-10:Tumor necrosis factor (TNF)-alpha ratio is associated with TNF promoter variants and predicts malarial complications.

In individuals with severe malarial anemia, plasma levels of tumor necrosis factor (TNF)-alpha tend to exceed those of interleukin (IL)-10. In this study, IL-10:TNF plasma level ratios <1 were found to be a risk factor for both cerebral malaria and severe anemia (P=.009), whereas higher IL-10:TNF ratios were observed more frequently in hyperparasitemic individuals. When considering allelic variants of the TNF promoter in children with severe malaria, carriers of the wild type more frequently had an IL-10:TNF ratio >1 (P=.008). In contrast, individuals with a mutation at position -238 of the TNF promoter (TNF(-238A) and TNF(-376A/-238A)) consistently had lower IL-10 than TNF plasma levels (IL-10:TNF ratio <1; P=.003). Our results show that, in children with severe malaria, TNF promoter variants influence the balance of IL-10:TNF in the plasma, which, in turn, affects the outcome in terms of clinical complications.

Liver transplantation for cholangiocarcinoma: results in 207 patients.

BACKGROUND: Because of the high incidence of recurrent tumor, many surgeons have become disenchanted with transplantation as a treatment for cholangiocarcinoma. METHODS: The Cincinnati Transplant Tumor Registry database was used to examine 207 patients who underwent liver transplantation for otherwise unresectable cholangiocarcinoma or cholangiohepatoma. Specific factors evaluated included tumor size, presence of multiple nodules, evidence of tumor spread at surgery, and treatment with adjuvant chemotherapy and/or radiation therapy. Incidentally found tumors were compared to tumors that were known or suspected to be present before transplantation. RESULTS: The 1, 2, and 5-year survival estimates using life table analysis were 72, 48, and 23%. Fifty-one percent of patients had recurrence of their tumors after transplantation and 84% of recurrences occurred within 2 years of transplantation. Survival after recurrence was rarely more than 1 year. Forty-seven percent of recurrences occurred in the allograft and 30% in the lungs. Tumor recurrence, and evidence of tumor spread at the time of surgery, were negative prognostic variables. There were no positive prognostic variables. Patients with incidentally found cholangiocarcinomas did not have improved survival over patients with known or suspected tumors. A small number of patients survived for more than 5 years without recurrence. However, this group had no variable in common that would aid in the selection of similar patients in the future. CONCLUSIONS: Because of the high rate of recurrent tumor and lack of positive prognostic variables, transplantation should seldom be used as a treatment for cholangiocarcinoma. For transplantation to be a viable treatment in the future, more effective adjuvant therapies are necessary.

Red cell glucose-6-phosphate dehydrogenase status and pyruvate kinase activity in a Nigerian population.

Glucose-6-phosphate dehydrogenase A- (G6PD A-) deficiency is a common enzymopathy in Africa that sporadically leads to manifest haemolytic anaemia. It is not exactly known how far the haematological status of individuals with either homozygous or heterozygous G6PD A- deficiency differs from that of individuals with normal G6PD activity. In a field study in Nigeria, we determined G6PD gene variants, the corresponding G6PD and pyruvate kinase (PK) activities, and basic haematological parameters in clinically healthy individuals, who were, in part, asymptomatically infected by malaria parasites. Red blood cell counts and haemoglobin levels were lower in G6PD A- deficient than in G6PD normal subjects. PK activities were higher in G6PD deficients, indicating a younger red cell population in these individuals. These findings suggest that G6PD A- deficiency is accompanied by chronic subclinical haemolysis. As a consequence, the reduced life span of red cells leads to an impaired diagnosis of G6PD heterozygosity when applying routine biochemical methods.