Presence of <Emphasis Type="Italic">C. albidus</Emphasis>, <Emphasis Type="Italic">C. laurentii</Emphasis> and <Emphasis Type="Italic">C. uniguttulatus</Emphasis> in Crop and Droppings of Pigeon Lofts (<Emphasis Type="Italic">Columba livia</Emphasis>)

Columba livia is an important reservoir and carrier of Cryptococcus neoformans, Cryptococcus uniguttulatus, Cryptococcus laurentii and Cryptococcus albidus. Upper digestive tract of this species is also known as a habitat for Cryptococcus neoformans. Given the increasing clinical interest of this microorganism, 331 swabs from crop and 174 dropping samples from pigeon lofts in Grand Canary Island have been studied. The obtained results show an extensive presence samples 81 positive (24.47%) of Cryptococcus spp. in analysed crops: 32 (9.66%) for C. neoformans, 24 (7.2%) for C. uniguttulatus, 23 (6.9%) for C. albidus and 2 (0.6%) for C. laurentii. In the same way, Cryptococcus spp was also isolated in 82 (47.13%), dropping samples: C. neoformans in 59 (33.9%), C. uniguttulatus, in 9 (5.17%), C. laurentii in 8 (4.59%) and C. albidus in 6 (3.44%) of the investigated samples, respectively. The cryptococcosis produced by species of cryptococci other than C. neoformans has become more important during the last decade, supporting the study on the role of pigeon in the epidemiology of this disease.     

Fickean and Non-Fickean Water Desorption During Vacuum Drying of <Emphasis Type="Italic">L. bulgaricus</Emphasis>

The recovery of Lactobacillus bulgaricus was studied in correlation to the kinetics of cell drying. When bacteria were dehydrated at 30 °C, either in the presence or the absence of sucrose, the drying kinetics corresponds to a Fickean diffusion in correspondence with a short lag time. In contrast, when the bacteria were dehydrated at 70 °C in the absence of sugar, the kinetics corresponds to an anomalous diffusion, and the lag time is four to five times higher than that at 30 °C. However, when drying at 70 °C was carried out in the presence of sucrose, drying kinetics turned into a Fickean process parallel to a substantial decrease in the lag time. The pattern of water desorption was correlated with the critical water activity. When the drying kinetics corresponds to a Fickean diffusion, the lag time started to increase at 0.7 water activity, but when the cells were dried at 70 °C, the damage started at 0.5 water activity. This observation indicates that the drying rate affects the pattern of water desorption, and it can change the value of critical water activity. These results put into relevance that the cell recovery is due to the drying history and that the recovery increase produced by sucrose can be related to the maintenance of kinetic barriers for water desorption.     

Experimental infections of simians with human malaria: attempts to infect Callithrix penicillata with Plasmodium falciparum

After reviewing the use of non-human primates of the Old and New Worlds for human malaria research, we concluded that another experimental animal which is easily available to use and possible to rear indoors is needed. Thus, we studied the susceptibility of the marmoset Callithrix penicillata to Plasmodium falciparum erythrocytic infections. The marmosets received various P. falciparum human isolates, directly from a patient and from continuous cultures. The Palo Alto strain, which has been adapted to the night monkey Aotus trivirgatus and further maintained in the squirrel monkey Saimiri sciureus was also used. In a total of 20 marmosets we performed 31 inoculations, with 10(5) to 10(9) parasites, intraperitoneally, intracardiacly or intravenously. Blood samples from each animal were examined daily up to day 90 post-inoculation. None of the intact marmosets developed patent infections. Four out of 19 C. penicillata, previously splenectomized, showed circulating parasites for up to five days after intravenous inoculation with the Palo Alto strain, becoming negative thereafter. Neither the addition to the simian diet of p-aminobenzoic acid, essential for the parasite metabolism, nor drug-immunosuppression, improved the marmoset susceptibility to P. falciparum.     

Structure of a protein catalyzing the formation of 11 cis-retinal in the visual cycle of invertebrate eyes

A pigment made up of a protein able to bind retinal as well as retinol is described. The molecule consists of a dimer with a molecular weight of 50,000 which binds one molecule of retinal. The binding site for retinal is a Schiff base buried in the interior of the protein. Retinol is probably bound to the protein in the same site as for retinal, although not covalently, as suggested by the absorbance spectra. The protein, extracted from honeybee retina, is involved in visual pigment metabolism, and its structure may elucidate the mechanism of the stereospecific photoisomerization of all trans-retinal to 11-cis-retinal.     

Effect of rate of change of luteinizing hormone concentration on in-vitro progesterone secretion within rat corpora lutea during differentiation.

Immature rats were injected with pregnant mares' serum gonadotrophin followed by human chorionic gonadotrophin (hCG). Ovaries were removed 0, 2, 5 or 8 days after hCG and either prepared for morphometric analysis or perifused with 0, 5 or 30 ng luteinizing hormone (LH)/min. In a second study, ovaries were removed on Day 2 or 8 and perifused with 0.1 mg 8-br-cyclic adenosine 5'-phosphate/ml (8-br-cAMP). On Day 0, the granulosa cells of the preovulatory follicles were small (53 +/- 0.5 microns2) with a cytoplasmic to nuclear (Cy:Nu) ratio less than or equal to 1.5. By Day 2, corpora lutea (CL) were present and composed of 95% small luteal cells (diameter less than 125 microns2, Cy:Nu greater than or equal to 3.0) and 5% large luteal cells (diameter greater than 125 microns2, Cy:Nu ratio greater than or equal to 3.0). The percentage of large luteal cells increased to 36 +/- 7% by Day 5, suggesting that they are derived from a select population of small luteal cells. Basal progesterone secretion increased from 38 +/- 5 on Day 0 to 1010 +/- 48 pg/mg/ml on Day 8. The rate of 5 ng LH/min stimulated progesterone secretion on Days 0, 2 and 8; 30 ng LH/min stimulated progesterone secretion on Days 0, 2 and 8, but not on Day 5; 8-br-cAMP stimulated progesterone secretion on both Days 2 and 8. These data demonstrate that once granulosa cells are induced to luteinize they lose their capacity to secrete progesterone in response to 5 ng LH/min and do not regain their responsiveness to LH rate until they completely differentiate. The loss of this LH responsiveness appears to be due to an inability to stimulate sufficient intracellular cAMP concentrations, since cAMP stimulates progesterone secretion on both Days 2 and 8.     

Effect of pulse amplitude of luteinizing hormone, duration and rate of change on progesterone secretion from rat corpora lutea.

Corpora lutea (CL) were obtained from immature rats primed with pregnant mares' serum gonadotrophin followed by human chorionic gonadotrophin (hCG). Two days after hCG, CL were isolated, placed in perifusion culture and exposed to control medium or specific pulses of luteinizing hormone (LH). In Expt 1, a frequency of 1 pulse LH/h (amplitude 500 pg/ml, duration 40 min, 30 ng/min) increased progesterone secretion compared with control values (P less than 0.05). In Expt 2, LH rate was held constant and the amplitude and duration of a single LH pulse varied; 250 and 500 ng LH/ml initially stimulated progesterone secretion equivalently, but increasing the duration of the LH pulse prolonged high progesterone secretion. These observations suggest that at less than or equal to 500 ng LH/ml, once a stimulatory amplitude is obtained, higher amplitudes do not further increase progesterone secretion, while increasing pulse duration further enhances progesterone secretion. In Expt 3, the LH pulse amplitude was 250 ng/ml and the rate set at 0, 5 or 30 ng LH/min; only 30 ng LH/min resulted in sustained stimulation of progesterone (P less than 0.05). Taken together, these data demonstrate that the characteristics which determine whether an LH pulse will be stimulatory include not only amplitude and duration but also the rate at which an amplitude is obtained.     

Isolation and genetic structure of IS112, an insertion sequence responsible for the inactivation of the SalI restriction-modification system of Streptomyces albus G.

Summary IS112 is a transposable element identified in Streptomyces albus G by its frequent mutagenic insertion into the genes for the SalI restriction-modification system. IS112 is present in several copies in the genome of S. albus G. Homologous sequences were detected in other Streptomyces strains. Sequence analysis revealed that IS112 has a length of 883 by with a GC content of 67.4%. The copy that was isolated contained imperfect inverted repeats (16/20 match) at its ends and was flanked by a 2 by duplication at the target site, which was located within the gene (salIR) for the Sall endonuclease. A long open reading frame (ORF) encoding a putative polypeptide of 256-253 amino acids spans almost the entire sequence. Significant homology was detected between this polypeptide and that corresponding to ORFB of IS493, an insertion sequence recently isolated from Streptomyces lividans 66.

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Enzymatic hydrolysis of 2,2,2,-trifluoroethyl α-chloro-α-phenylacetate in organic media

Summary 2,2,2-Trifluoroethyl -chloro--phenylacetate is succesfully hydrolysed in organic solvent in the presence of aniline andCandida cylindracea orPseudomonas cepacia lipase as catalysts.     

Ethinylestradiol administration selectively alters liver sinusoidal membrane lipid fluidity and protein composition

Administration of high-dose ethinylestradiol to rats decreases bile flow, Na,K-ATPase specific activity, and liver plasma membrane fluidity. By use of highly purified sinusoidal and bile canalicular membrane fractions, the effect of ethinylestradiol administration on the protein and lipid composition and fluidity of plasma membrane fractions was examined. In sinusoidal fractions, ethinylestradiol (EE) administration decreased Na,K-ATPase activity (32%) and increased activities of alkaline phosphatase (254%), Mg2+-ATPase (155%), and a 160-kDa polypeptide (10-fold). Steady-state and dynamic fluorescence polarization was used to study membrane lipid structure. Steady-state polarization of diphenylhexatriene (DPH) was significantly higher in canalicular compared to sinusoidal membrane fractions. Ethinylestradiol (5 mg/kg per day for 5 days) selectively increased sinusoidal polarization values. Similar changes were demonstrated with the probes 2- and 12-anthroyloxystearate. Time-resolved fluorescence polarization measurements indicated that EE administration for 5 days did not change DPH lifetime but increased the order component (r infinity) and decreased the rotation rate (R). However, 1 and 3 days after EE administration and with low doses (10-100 micrograms/kg per day for 5 days) the Na,K-ATPase, bile flow, and order component were altered, but the rotation rate was unchanged. Vesicles prepared from total sinusoidal membrane lipids of EE-treated rats, as well as phospholipid vesicles, demonstrated increased DPH polarization, as did intact plasma membrane fractions. Liver plasma membrane fractions showed no change in free cholesterol or cholesterol/phospholipid molar ratio, while esterified cholesterol content was increased with high-dose but not low-dose ethinylestradiol.(ABSTRACT TRUNCATED AT 250 WORDS)