Life cycle and influence of age and feeding on the first mating of Triatoma mazzottii (Hemiptera: Reduviidae)

A cohort of 100 eggs of Triatoma mazzottii Usinger was studied to obtain information on its life cycle. Egg incubation took 24 days; mean duration of 1st, 2nd, 3rd, 4th, and 5th instar nymphs was 27, 36, 39, 46 and 64 days respectively; mean time from egg to adult was 236 days. The total duration of the nymphal stages was 212 days. The total nymph mortality in cohort was 16.3% and the embryonic egg mortality was 14.0%. The grater mortality occured in the 2nd instar. The average number of eggs/female/week was 9.8 during 15 weeks of observation. Of the total eggs laid (2,514), only 58.7% hatched. The total of insects that achieved the adult stage (72), 38 were females (52.8%), and 34 were males (47.2%). The influence of age and feeding on the first mating of T. mazzottii were also studied. It was found that the first mating depended on the male's age and it was on the average 30 days after the last imaginal molt. The female could be mating since 2nd days after the imaginal life. The nutritional status did not play an important role in the capacity of the insect for the first mating.

Development of sporogonic cycle of Plasmodium vivax in experimentally infected Anopheles albimanus mosquitoes

The sporogonic cycle of Plasmodium vivax was established and maintained under laboratory conditions in two different strains of Anopheles albimanus mosquitoes using as a parasite source blood from human patients or from Aotus monkeys infected with the VCC-2 P.vivax colombian isolate. Both the Tecojate strain isolate from Guatemala and the Cartagena strain from the colombian Pacific coast were susceptible to infections with P.vivax. A higher percentage of Cartagena mosquitoes was infected per trial, however the Tecojate strain developed higher sporozoite loads. Intravenous inoculation of Aotus monkeys with sporozoites obtained from both anopheline strains resulted in successful blood infections. Animals infected with sporozoites from the Tecojate strain presented a patent period of 21-32 days whereas parasitemia appeared between days 19-53 in monkeys infected with sporozites from Cartagena strain.

Acute creatine loading enhances human growth hormone secretion.

BACKGROUND: The main objective of this study was to explore the effect of acute creatine (Cr) ingestion on the secretion of human growth hormone (GH). METHODS: In a comparative cross-sectional study, 6 healthy male subjects ingested in resting conditions a single dose of 20 g creatine (Cr-test) vs a control (c-test). During 6 hours the Cr, creatinine and GH concentrations in blood serum were measured after Cr ingestion (Cr-test). RESULTS: During the Cr-test, all subjects showed a significant stimulation of GH (p<0.05), but with a large interindividual variability in the GH response: the difference between Cr-test and c-test averaged 83% (SD 45%). For the majority of subjects the maximum GH concentration occurred between 2 hrs and 6 hrs after the acute Cr ingestion. CONCLUSIONS: In resting conditions and at high dosages Cr enhances GH secretion, mimicking the response of strong exercise which also stimulates GH secretion. Acute body weight gain and strength increase observed after Cr supplementation should consider the indirect anabolic property of Cr.

In vivo detection of brain Krebs cycle intermediate by hyperpolarized magnetic resonance.

The Krebs (or tricarboxylic acid (TCA)) cycle has a central role in the regulation of brain energy regulation and metabolism, yet brain TCA cycle intermediates have never been directly detected in vivo. This study reports the first direct in vivo observation of a TCA cycle intermediate in intact brain, namely, 2-oxoglutarate, a key biomolecule connecting metabolism to neuronal activity. Our observation reveals important information about in vivo biochemical processes hitherto considered undetectable. In particular, it provides direct evidence that transport across the inner mitochondria membrane is rate limiting in the brain. The hyperpolarized magnetic resonance protocol designed for this study opens the way to direct and real-time studies of TCA cycle kinetics.

Variable phenotypic expressivity in a Swiss family with autosomal dominant retinitis pigmentosa due to mutation T494m in the Prpf3 gene

Purpose:to describe the clinical features in a five generations family segregating autosomal dominant retinitis pigmentosa and to identify the causative gene Patient and Methods:Twenty five individuals of a large five-generation family originating from Western Switzerland were ascertained for phenotypic and genotypic characterization. Ophthalmologic evaluations included color vision testing, Goldman perimetry and digital fundus photography. Some patients had autofluorescence (AF) imaging, ocular coherence tomography (OCT) and ISCEV-standard full-field electroretinography (ERG). Blood samples were collected from 10 affected (4 to 70 years of age) and 15 unaffected members after informed consent. DNA was isolated and exons and intron-exons junctions of known adRP genes were sequenced using a Big Dye sequencing kit 1.1. Results:Age of onset of nightblindness and severity of progression of the disease was variable between members of the family. Some patients had early onset of nightblindess aged 3, others at mid-twenties. Most patients had visual acuity above 0.6 for the first 4 decades. Two older patients still had good vision (0.4) in their seventies. Myopia (range: -2 to -5) was noticed in most affected subjects. Fundus findings showed areas of atrophy along the arcades. The AF imaging showed a large high density ring bilaterally. A T494M change was found in exon 11 of PRPF3 gene. The change segregates with the disease in the family. Conclusion: A mutation in the PRPF3 gene is rare compared with other genes causing ADRP. Although a T494M change has been reported, our family is the first one with a variable expressivity. Mutations in PRPF3 gene can cause a variable phenotype of ADRP unlike the previously described Danish and English families. Our report gives a better understanding as to the phenotype/genotype description of ADRP due to PRPF3 mutation.

Thermal effect on the life-cycle parameters of the medically important freshwater snail species Lymnaea (Radix) luteola (Lamarck)

The snails Lymnaea (Radix) luteola exhibited marked variations in growth, longevity, and attaining sexual maturity at different temperatures and diets. At 10°C, irrespective of foods, pH and salinity of water, the snails had minimum life span, maximum death rate and lowest growth rate. At 15°C, the growth rate was comparatively higher and the snails survived for a few more days. But at these temperatures they failed to attain sexual maturity. Snails exposed to pH 5 and 9 at 20°, 25°, 30°, 35°C and room temperatures (19.6°-29.6°C); to 0.5, 1.5 and 2.5 NaCl ‰ at 20° and 35ºC; to 2.5 NaCl ‰ at 25°C and room temperatures failed to attain sexual maturity. The snails exposed to pH 7 and different salinity grades at 20°, 25°, 30°, 35°C and room temperatures became sexually mature between 25-93 days depending upon the type of foods used in the culture.

A two years study on vectors of cutaneous leishmaniasis: Evidence for sylvatic transmission cycle in the State of Campeche, Mexico

Vectors of cutaneous leishmaniasis in the State of Campeche were studied in relation to the transmission cycle of Leishmania (Le.) mexicana. To determine how transmission of leishmaniasis occurs, we collected phlebotomine sand flies for two years. In the first year (October 1990 to November 1991) the collections were made with CDC light traps, Shannon traps and direct captures at natural shelters around the village (<200 m) of La Libertad. In the second year (February 1993 to January 1994) the catches were performed at 8 km southeast of La Libertad in the forest. Female sand flies were examined for Leishmania. During the first year, 347 sand flies of nine species were collected, most of which were Lutzomyia deleoni (61.3%). When all nine species were considered, more females than males were captured. Low densities of anthropophillic species of sand flies around the village indicated that sylvatic transmission was taking place. For the second year, 1484 sand flies of 16 species were caught. The most common were L. olmeca olmeca (21.7%), L. cruciata (19.2%) and L. ovallesi (14.1%). Similarly, more females were caught than males. Thirty-five females of five species were found infected with flagellates believed to be Leishmania sp. The highest infection rate was found in L. olmeca olmeca (7.1%) followed by L. cruciata (4.5%) and L. ovallesi (1.1%). These data plus other evidence on the epidemiology of human cases and results from reservoir studies are discussed in relation to the sylvatic transmission cycle.

Life cycle of a biologist.

Review of the book : "Lives of a biologist: Adventures in a century of extraordinary science", by J.T. Bonner, Harvard University Press, Cambridge, USA

A Simple Reverse Transcription-Polymerase Chain Reaction for Dengue Type 2 Virus Identification

We show here a simplified reverse transcription-polymerase chain reaction (RT-PCR) for identification of dengue type 2 virus. Three dengue type 2 virus strains, isolated from Brazilian patients, and yellow fever vaccine 17DD, as a negative control, were used in this study. C6/36 cells were infected with the virus, and tissue culture fluids were collected after 7 days of infection period. The RT-PCR, a combination of RT and PCR done after a single addition of reagents in a single reaction vessel was carried out following a digestion of virus with 1% Nonidet P-40. The 50ml assay reaction mixture included 50 pmol of a dengue type 2 specific primer pair amplifying a 210 base pair sequence of the envelope protein gene, 0.1 mM of the four deoxynucleoside triphosphates, 7.5U of reverse transcriptase, and 1U of thermostable Taq DNA polymerase. The reagent mixture was incubated for 15 min at 37oC for RT followed by a variable amount of cycles of two-step PCR amplification (92oC for 60 sec, 53oC for 60 sec) with slow temperature increment. The PCR products were subjected to 1.7% agarose gel electrophoresis and visualized with UV light after gel incubation in ethidium bromide solution. DNA bands were observed after 25 and 30 cycles of PCR. Virus amount as low as 102.8 TCID50/ml was detected by RT-PCR. Specific DNA amplification was observed with the three dengue type 2 strains. This assay has advantages compared to other RT-PCRs: it avoids laborious extraction of virus RNA; the combination of RT and PCR reduces assay time, facilitates the performance and reduces risk of contamination; the two-step PCR cycle produces a clear DNA amplification, saves assay time and simplifies the technique

Nocardiose oculaire endogène

IntroductionNous avons diagnostiqué et traité un patient atteint de nocardiose oculaire endogène. Grâce à la chirurgie vitréo-rétinienne, le diagnostique définitif a pu être établi avec un résultat oculaire fonctionnel excellent. La nocardiose oculaire endogène étant une maladie rare, l'image clinique oculaire et la prise en charge n'ont pas encore été décrites systématiquement. Nous avons analysé tous les cas rapportés dans la littérature mondiale (38 cas, publiés jusqu'en 2007) pour trouver des indices sur la physiopathologie, la présentation oculaire, sur la meilleure façon d'établir le diagnostique et sur l'efficacité du traitement antibiotique systémique. Enfin, nous avons établit des directives pour la prise en charge oculaire.La nocardiose (défini comme maladie systémique ou locale) est une maladie touchant surtout des patients immunosupprimés ou immunocompromis comme les patients transplantés, avec maladie auto-immune, atteints du virus HIV sans HAART ou des patients ayant subit un trauma, une opération avec inoculation du germe. Aux Etats-Unis environs 500-1000 nouveaux cas sont diagnostiqués par année avec 20% de dissémination dans des autres organes, le plus fréquemment dans le cerveau. Environs 0.6-1% des patients (3-5 cas/année/US) auront un foyer dans l'oeil, c'est-à-dire la nocardiose oculaire endogène. Nocarida est un Actinomycète, classé comme bactérie, avec une morphologie et un comportement proche aux champignons, avec un cycle de reproduction lente, se trouvant dans la poussière (ubiquitaire) et la matière végétale se décomposant. Elle est sensible aux sulfamides avec émergence de résistances. La mortalité est environs de 25%.RésultatsLa moitié des patients présentait comme premier signe de la maladie systémique des problèmes oculaires, le plus souvent une baisse d'acuité visuelle progressive indolore. Un abcès choroïdien unilatéral unique dans la région maculaire associé ou non à un décollement rétinien séreux et/ou à une vitrite variable était la présentation dans 70% des cas. Nocardia dissémine au niveau des choriocapillaires, rarement, dans l'iris résultant dans un hypopyon isolé. Il y a deux modes de propagation locale: vers l'intérieur, par une nécrose de l'épithélium pigmentaire avec l'envahissement de la rétine et du corps vitré; vers l'extérieure, produisant une sclérite résultant dans une perforation du globe. Avant la séquestration au niveau du corps vitré, la réponse au traitement par antibiose voie générale est favorable: 75% des cas analysés. La rupture de la barrière hémato-oculaire externe (épithélium pigmentaire) peut être mis en évidence par la fluorescence angiographique : les images tardives montrent la diffusion de la fluorescéine dans le corps vitré. Si le corps vitré est atteint, au minimum des injections antibiotiques intravitréen (amikacin), mieux une vitréctomie sont indiqué pour diminuer la charge bactérienne et faciliter la pénétration des antibiotiques donnés par voie systémique. Signes d'une extériorisation d'un abcès choroïdien sont des douleurs intenses, l'exophthalmie et l'hypopyon associé.Soixante-deux pourcents des patients ont souffert d'une dissémination continue par retardement du diagnostique/traitement. La moitié des patients ont eu des abcès cérébraux avant, simultanément ou après présentation. Un quart des patients sont décédés suite de la nocardiose, 32% incluant la maladie de base (tumeur maligne hématologique) ou des autres infections opportunistiques (aspergillose). La morbidité oculaire est importante: un tiers des patients survivants ont retenu une acuité visuelle 0.5 ou mieux, un tiers une acuité visuelle égale ou inférieure à 0.1 et un tiers ont perdu l'oeil par énucléation/éviscération(l). La suspicion clinique et la biopsie de la lésion pour un examen microbiologique direct et des cultures sont cruciales pour la prise en charge. Les risques facteurs sont sexe masculin (4 :1), stéroïdes, immunosuppression pour transplantation ou maladie auto-immune et des tumeurs hématologiques malignes, plus rarement des accidents/ traumas graves. La ponction directe de la lésion assure les meilleures chances pour collectionner un spécimen contenant des bactéries: dans des petits abcès sous-rétiniens maculaires par ponction transvitréenne sous-rétinienne par aiguille fine décrit par le Prof. Augsburger (Référence 7) ou dans des lésions avancées par biopsie sous-rétinienne/rétinienne pendant une vitréctomie selon l'extension et la localisation de l'abcès. Le spécimen doit être préparé pour un examen direct (4 lames) et des cultures utilisant des plaques ordinaires sauf exceptions. La suspicion doit être communiquée au laboratoire et les cultures incubées de façon prolongée (4-6 semaines). Un bilan d'extension avec au minimum un CT scan thoracique et une IRM cérébrale sont indiqués.Le traitement de choix est un antibiotique du groupe des sulfamides à haute dose comme par exemple le co- trimoxazole à double dose. Le choix, le nombre et le dosage du/des médicaments doivent être adapté selon résistance, extension de la maladie, médicaments autres et état de santé général du patient (foie, reins). Les figures 6a et 6b illustrent la prise en charge de patients selon diagnostique établit (Fig. 6b) ou non (Fig 6a).

Comparative Histopathology of Biomphalaria glabrata, B. tenagophila and B. straminea with Variable Degrees of Resistance to Schistosoma mansoni Miracidia

A comparative histopathological study of three snails species - Biomphalaria glabrata, B. tenagophila and B. straminea - which had been infected with Schistosoma mansoni miracidia revealed similar qualitative features, consisting of areas of sporocyst proliferation and differentiation associated with reactive host reaction, at the time they were actively eliminating great number of cercariae. However, in specimens that were exposed to miracidia but failed to eliminate cercariae later on, different histopathological pictures were observed in different snail species. While B. glabrata exhibited frequent focal (granulomatous) proliferation of amebocytes in several organs, B. tenagophila and B. straminea only rarely showed such reactive changes, suggesting that the mechanism of resistance to miracidial infection probably follows different pathways in the snail species studied

Two monoclonal rat antibodies with specificity for the beta-chain variable region V beta 6 of the murine T-cell receptor.

Two rat monoclonal antibodies (mAbs), 44-22-1 and 46-6B5, which recognize an alloreactive cytotoxic clone, 3F9, have been further tested on a panel of T hybridomas and cytotoxic T-cell clones for binding and functional activities. The mAbs recognized only those cells sharing the expression of the T-cell receptor beta-chain variable region gene V beta 6 with 3F9. All V beta 6+ cells were activated by these mAbs under cross-linking conditions and their antigen-specific activation was blocked by soluble mAb. Furthermore, depletion of 46-6B5+ normal lymph node T cells eliminated all cells expressing the epitope recognized by 44-22-1 and V beta 6 mRNA.

Macroeconomic shocks and the business cycle: evidence from a structural factor model

We use a dynamic factor model to provide a semi-structural representation for 101 quarterly US macroeconomic series. We find that (i) the US economy is well described by a number of structural shocks between two and six. Focusing on the four-shock specification, we identify, using sign restrictions, two non-policy shocks, demand and supply, and two policy shocks, monetary and fiscal. We obtain the following results. (ii) Both supply and demand shocks are important sources of fluctuations; supply prevails for GDP, while demand prevails for employment and inflation. (ii) Policy matters, Both monetary and fiscal policy shocks have sizeable effects on output and prices, with little evidence of crowding out; both monetary and fiscal authorities implement important systematic countercyclical policies reacting to demand shocks. (iii) Negative demand shocks have a large long-run positive effect on productivity, consistently with the Schumpeterian "cleansing" view of recessions.