Effect of interferon on the infectivity of Trypanosoma cruzi in cultured HeLa cells

Results are presented on the effects of human lymphoblastoid interferon (HUIFN-α-ly) on the infectivity of metacyclic culture forms of Trypanosoma cruzi in HeLa cells. When cells were pretreated with interferon the parasitisation ratios of the cultures increased with respect to controls. This phenomenon also occurs when interferon was added during the period of parasite-cell interaction. When parasites were pretreated with interferon but cells were not, no increase in the parasitisation ratios was observed.     

Some factors affecting the in vitro invasion of HeLa cells by Trypanosoma cruzi

The penetration of metacyclic forms of Trypanosoma cruzi into HeLa cells after different treatments was studied. When cell development was synchronized by two different processes, maximum rates of parasitization occurred during the S phase of cell cycle (29.48 and 24.3%). However, when cells were treated with trypsin (0.1%), parasitization rates appeared to be lower than controls, reaching values similar to controls 14 h after the beginning of the treatment. Infection values remained unaltered after treatment with colcemid (0.6 μg ml^?1). Cell treatment either with valinomycin (1 μg ml^?1) or with actinomycin D (250 μg ml^?1) caused a marked decrease in the percentage of parasitization. When cells were treated and infected in the presence of tunicamycin (100 ng ml^?1), parasitization rates were increased (14.7%) compared to control cells (6%). On the other hand, no differences in parasitization rates were observed when cells were treated with cycloheximide (100 μg ml^?1). Infection in a low redox medium (?100 mV) resulted in considerable increase in parasitization.     

Treatment of acute otitis media: a controlled study of 142 children

Results of the use of ampicillin, penicillin G and symptomatic therapy in the treatment of acute otitis media in 142 children were compared. Antibiotic therapy conveyed significant benefit. No major differences were observed between penicillin and ampicillin, except in the age group under 3 years where ampicillin was associated with the best results. Ampicillin appears to be the drug of choice. Its superiority over symptomatic therapy was statistically significant. Long-term sequelae were not observed in any of the three treatment groups. The relative merits of erythromycin and ampicillin require further study.     

Effect of CRF injected into the median eminence on GH secretion in female rats under different steroid status

To evaluate whether the median eminence (ME) is a site of action of CRF (corticotropin releasing factor) on GH secretion and to determine the possible role of estradiol and progesterone in modifying theses secretion, we injected CRF (0.25, 0.75, 1, and 1.5 nmol of peptide dissolved in 1 μl of water) directly into the ME in three experimental groups of rats: Long-term ovariectomized (OVX); OVX primed by estradiol (OVX±E) and OVX primed by estradiol plus progesterone (OVX±EP). Blood was collected to determine GH (30, 60, 90, and 120 min postinjection) Serum T₃, T₄, and glucose levels were measured in OVX±E rats 30 min postinjection. CRF at all doses studied significantly decreased serum GH levels in the three experimental groups. Serum T₃, T₄, and glucose levels were unchanged after CRF administration. The results suggest that: CRF inhibits “per se” GH secretion, at least in part, by a central action in the ME. The inhibitory effect of CRF on GH is independent of the estrogen/progesterone status of the animal. CRF at ME levels may participate in a variety of stress-related responses, including growth inhibition, through GH suppression.     

Spermatophore development and sperm ultrastructure inCraterostigmus tasmanianus (Chilopoda,Craterostigmomorpha)

 Spermatophore development and ultrastructure of the mature sperm of Craterostigmus tasmanianus were studied using light and electron microscopy. In C. tasmanianus, as in the Scolopendromorpha, the spermatophore develops within the vas deferens. The latter consists of three parts, each with a different morphology. The first may be involved in guiding the sperm to roll up into typical ring-like structures, while the other two, which show an evident secretory activity, secrete the acellular wall of the spermatophores. The ultrastructure of mature spermatozoa showed that a very close similarity exists between Craterostigmomorpha and Lithobiomorpha, especially regarding the organization of the connecting piece. Based on this similarity, we consider the Craterostigmomorpha together with the Scolopendromorpha, Geophilomorpha and Lithobiomorpha (=Pleurostigmophora) to be the sister group of the Scutigeromorpha. Accepted: 2 June 1996     

Isolation and promoter characterization of barley geneItr1 encoding trypsin inhibitor BTI-CMe: differential activity in wild-type and mutantlys3a endosperm

The geneItr1, encoding trypsin inhibitor BTI-CMe, has been obtained from a genomic library ofHordeum vulgare L. The gene has no introns and presents in its 5-upstream region 605 bp that are homologous to the long terminal repeats (LTR) of the copia-like retro-transposon Bare-1. Functional analysis of theItr1 promoter by transient expression in protoplasts derived from different barley tissues, has shown that in this system theItr1 promoter retains its endosperm specifity and thetrans-regulation mediated by theLys3a gene. The proximal promoter extending 343 bp upstream of the translation initiation ATG codon is sufficient to confer fullGUS expression and for endosperm specifity. In protoplasts derived from thelys3a mutant, Risø 1508,GUS activity was less than 5% of that obtained with the same constructs in the protoplasts of wild-type Bomi from which it derives. Gel retardation experiments, after incubation with proteins obtained from both types of endosperm nuclei, also show differential patterns. Possible reasons for these differences are discussed.Equal authours     

Study of the phagocytic process in neutrophils from elite sportswomen

All the stages of the phagocytic process of blood neutrophils were compared in sedentary young women (no formal exercise during the previous 24 months) and elite sportswomen (basketball players from the Siglo XXI Spain Selection, in the middle of their competitive season) at rest. The sportswomen had performed no exercise since the day before taking the blood samples. Adherence of neutrophils to nylon fibre, which is similar to endothelium adherence, was not different between the two groups [62 (SD 14) and 58 (SD 18) in control and sport groups respectively]. Chemotaxis (studied in a Boyden chamber using a filter with 3 m pore diameter) was found to be stimulated (P<0.001) in the sportswomen [105 (SD 30)] with respect to the controls [39 (SD 9)]. Attachment, ingestion and killing by neutrophils was measured by incubation of the neutrophils with serum and a suspension ofCandida albicans. While no statistical differences were found in attachment ofC. albicans after 15 min incubation [71 (SD 8) in the control group, and 74 (SD 20) in the sport group], the sportswomen showed a higher (P<0.001) ingestion capacity forC. albicans at both 15 min [53 (SD 13) and 111 (SD 32) in control and sportswomen respectively] and 60 min [control 90 (SD 10), and sport group 224 (SD 21)] incubation. The greater phagocytic capacity in sportswomen was correlated with a higher plasma cortisol concentration (P <0.05) and a lower plasma ACTH concentration (P <0.001) in this group. It is concluded that elite women basketball players have a greater phagocytic capacity than sedentary women, possibly mediated by the higher plasma cortisol concentration in the sportswomen.     

Vegetation Changes Following Large-scale Fence Removal Across a Protected Area Network Within the Kruger to Canyons Biosphere Reserve,South Africa

Ecosystems - In the early 1990’s, reserves adjacent to Kruger National Park (KNP) removed their fences to create a continuous landscape within the Kruger to Canyons Biosphere Reserve....     

Effect of stress,adrenalectomy and changes in glutathione metabolism on rat kidney metallothionein content: comparison with liver metallothionein

Eighteen hours of immobilization stress, accompanied by food and water deprivation, increased liver metallothionein (MT) but decreased kidney MT levels. Food and water deprivation alone had a significant effect only on liver MT levels. In contrast, stress and food and water deprivation increased both liver and kidney lipid peroxidation levels, indicating that the relationship between MT and lipid peroxidation levels (an index of free radical production) is unclear. Adrenalectomy increased both liver and kidney MT levels in basal conditions, whereas the administration of corticosterone in the drinking water completely reversed the effect of adrenalectomy, indicating an inhibitory role of glucocorticoids on MT regulation in both tissues. Changes in glutathione (GSH) metabolism produced significant effects on kidney MT levels. Thus, the administration of buthionine sulfoximine, an inhibitor of GSH synthesis, decreased kidney GSH and increased kidney MT content, suggesting that increased cysteine pools because of decreased GSH synthesis might increase kidney MT levels through an undetermined mechanism as it appears to be the case in the liver. However, attempts to increase kidney MT levels by the administration of cysteine or GSH were unsuccesful, in contrast to what is known for the liver. The present results suggest that there are similarities but also substantial differences between liver and kidney MT regulation in these experimental conditions.