ATHEROMATOSIS OF THE BRAIN-SUPPLYING ARTERIES: CIRCLE OF WILLIS, BASILAR, VERTEBRAL AND THEIR BRANCHES

PURPOSE

Atherosclerotic plaques in the brain-supplying arteries are slowly-developing alterations of vascular structures that can lead to neurological impairment due to stenosis and insufficient oxygenation of eloquent brain areas. The aim of this study is to provide detailed demographic information related to the incidence of atherosclerotic plaques in the cerebral arteries.

MATERIAL AND METHODS

Forty-eight circles of Willis (21 men, 21 women, mean age: 70.26, six samples unknown) were macroscopically analyzed for length, diameter, and presence of atherosclerotic plaques. Statistical analysis was used to identify potential differences in the locations and frequencies of atherosclerotic plaques in relation to age and sex.

RESULTS

The study sample revealed 261 atherosclerotic plaques. The key findings were significant correlations between plaque development and age and between plaque location and age; however, there was no significant sex difference.

CONCLUSION

The upper and lower branches of the middle cerebral artery (MCA) were novel locations predisposing to plaque development. A cut-off value at 60 years revealed a significant difference in plaque development and distribution. There were no significant sex differences in the occurrence of atherosclerotic plaques.

Evaluation of COVID-19 case investigators’ interviewing skills in a portuguese public health unit

 

An effective control of the COVID-19 pandemic requires a thorough epidemiological interview of reported cases. The interviewer's skills and preparation directly affect the outcome of the investigation. This study applied a self-assessment survey of the COVID-19 patient interviewing skills on a local public health department workforce. The findings may be used to improve the quality of the interview process and the overall response to the pandemic at a community level. A 50-item questionnaire using a four-point Likert scale was adapted from the COVID-19 Patient Interview Skills Assessment Form created by the Centers for Disease Control and Prevention (CDC) and applied to 50 healthcare workers involved in epidemiological investigation of COVID-19 cases in Almada and Seixal, two municipalities of the Lisbon Metropolitan Area, from January to April of 2021. The most frequently executed steps concern checking patient data in advance (92%), questioning symptoms (97.2%), contact tracing (100%) and determining isolation periods for high risk contacts (100%). Least performed tasks include confirming the testing technique used (50%), asking about hospitalization (44.4%), assessing conditions for home isolation (44%), explaining how to self-monitor symptoms (61%) and checking if the patient understood the instructions (47%). In addition, 8% admitted to not always keeping patient information confidential. While caution is necessary as the data was limited to a single public health local department, our findings show that a majority of healthcare workers fulfill the essential steps of an epidemiological investigation. Areas in need of improvement include inquiring about infection severity, assessing social conditions for quarantine and confirming instructions for self-monitoring and follow-up. In line with CDC recommendations, we believe regular evaluation and feedback of case investigators' skills are crucial to quality assurance of a public health department.

Key messages

A detailed interview provides critical data for monitoring infected individuals and quickly trace, test and isolate those who might have been exposed, thus breaking chains of transmission. The results of this assessment can be used to introduce training measures such as shadowing and role-playing to ensure continued improvement in epidemiological investigations.

Mitochondrial DNA suggests cryptic speciation in Prodiplosis longifila Gagné (Diptera: Cecidomyiidae) associated with geographic distance and host specialization

Prodiplosis longifila is reported as a pest of a wide range of species cultivated in America, including citrus, solanaceous species and asparagus. This species has different behavioural traits that are primarily centred on the oviposition habit and the feeding of larvae, which can change depending on the host. However, scarce information is available on population studies and the natural history of this insect, and uncertainty exists about the taxonomic identity and the geographic distribution of this species. The main objective was to perform a phylogenetic and genetic study of P. longifila populations and to define whether the North American and South American populations belong to the same species or whether a differentiation process had occurred due to geographic distance. A second objective was to determine whether this species showed genetic differentiation by host specialization in South America. The phylogenetic and population analyses based on DNA barcodes (cytochrome oxidase I gene) and a region of the ribosomal DNA (ITS2) revealed divergent clades attributable to geographic distance and host specificity. The North American and South American P. longifila insects were confirmed to be genetically distinct, and the genetic distances exceeded the values expected for intraspecific variation. In South America, the population analysis of P. longifila from tomato, sweet pepper (Solanaceae), Tahiti lime and key lime (Rutaceae) hosts evidenced high genetic differentiation between populations associated with different hosts and an absence of gene flow between these groups, suggesting the corresponding formation of cryptic species.

Blackflies (Diptera: Simuliidae) of Southern Guyana with keys for the identification of adults and pupae: a review

A revision is made of the previously poorly studied blackfly fauna from the south-western border of Guyana with Brazil. Notes on the biosystematics of the species found are provided, together with keys and illustrations based on their morphology. Of the 14 species recorded, eight are anthropophilic and two of these (Simulium oyapockense s.l. and S. guianense s.l.) are proven vectors of human onchocerciasis in the nearby Amazonia focus of the disease in neighbouring Brazil.

Simulium lobatoi, new species of blackfly (Diptera: Simuliidae) from the states of Mato Grosso and Goiás, Central Brazil

During studies on the taxonomy of the Simuliidae of Brazil, a new species of Simulium was found. Full descriptions of the adults and pupae of this species are described here, its affinities with other species are discussed and its distribution, biology, and medical importance in Brazil are recorded.

4'-N-methyl-5'-hydroxystaurosporine and 5'-hydroxystaurosporine, new indolocarbazole alkaloids from a marine Micromonospora sp. strain

Two new indolocarbazole alkaloids, 4'-N-methyl-5'-hydroxystaurosporine (2) and 5'-hydroxystaurosporine (3), were isolated together with the known staurosporine (1) from the culture broth of a marine Micromonospora sp. (strain L-31-CLCO-002). The fermentation, structural data and cytotoxic activities of these compounds against various tumor cell lines are given.

Organochlorine and heavy metal residues in the water/sediment system of the Southeast Regional Park in Madrid, Spain

A study into levels of contamination by organochlorine compounds (insecticides and PCBs) and heavy metals (Cd and Pb) in the water/sediment system of the Southeast Regional Park (SERP) in Madrid, Spain, has been carried out. Residue levels of xenobiotics were determined in surface and underground waters and sediments from selected sites throughout the protected area. The results showed these contaminants to be widespread throughout the studied area. p,p'-DDT concentration levels were consistently higher than its metabolite p,p'-DDE, indicating a recent use of this organochlorine insecticide in the area. PCB levels exceeded, in the majority of the cases, the levels taken as the maximum (100 ng/microl) for highly polluted waters. Cd and Pb levels found in water samples were under the detection limits of the methodology used. Pb levels found in sediment samples were higher than Cd.

Study of the distribution of the polychlorinated biphenyls in the milk fat globule by supercritical fluid extraction

The distribution of polychlorinated biphenyls (PCBs) in the milk fat globule has been studied by sequential extraction of four different lipidic fractions from powdered full-fat milk with supercritical carbon dioxide. Extractions were carried out in the dynamic mode in the pressure range 13.6-23.3 MPa at a temperature of 50 degrees C. The levels of PCBs and short-chain triglycerides (SCT), medium-chain triglycerides (MCT) and long-chain triglycerides (LCT), as well as the cholesterol in these four supercritical fluid extraction (SFE) fractions were determined. Extracts obtained at lower pressures were found to be enriched in PCBs, SCT, MCT and cholesterol, while the concentrations of all these analytes decreased for subsequent extractions. Satisfactory quadratic correlations were found between the PCB and SCT and MCT levels (r2 in the range 0.9-0.999), and between the PCB and cholesterol levels (r2 in the range 0.8-0.999, except for PCB 105) determined in the SFE fractions. These results suggested a similar distribution of the PCBs and the cholesterol in the milk fat globule. This conclusion was also supported by the comparison of the PCBs and the cholesterol chemical structures as well as by the total PCB levels determined by SFE to those obtained by using different extraction methods. The classical requirement for the analysis of this kind of lipophilic pollutants of an exhaustive extraction of the lipids of the matrix to ensure their quantitative recovery has been revised.

The mnn2 mutant of Saccharomyces cerevisiae is affected in phosphorylation of N-linked oligosaccharides

We studied the phosphorylation of the inner core region of N-linked oligosaccharides in the mannan defective mutant Saccharomyces cerevisiae mnn2 which was described as unable to synthesize branches on the outer chain. We performed structural studies of the N-oligosaccharides synthesized by the strains mnn2, mnn1mnn2mnn9 and mnn1mnn9ldb8, and the results are compared with previously published structural data of mnn1mnn2mnn10 and mnn1mnn9 [Hernández, L.M., Ballou, L., Alvarado, E., Tsai, P.-K. and Ballou, C.E. (1989) J. Biol. Chem. 264, 13648-13659]. We conclude that the mnn2/ldb8 mutation is responsible for the inhibition of incorporation of phosphate to mannose A(3) (see below), a particular phosphorylation site of the inner core, while phosphorylation at the other possible site (mannose C(1)) is allowed, although it is also reduced. *Phosphorylation sites in mnn1mnn9. (see structure below)

Accumulation of heavy metals and As in wetland birds in the area around Doñana National Park affected by the Aznalcollar toxic spill

The impact of the spill from the mine in Aznalcollar (Seville, Spain) on waterfowl in the Doñana National Park is assessed. The concentrations of Cu, Pb, Cd, Zn nd As in the liver and eggs of 16 species of waterfowl found dead in the Park between April and November 1998 were determined. The highest levels were found for Zn, followed by Cu, Pb, Cd and As. The main parameters related to the accumulation of these elements in the waterfowl studied were species and trophic level. The other variables studied--distance from the spill, days of exposure, sex, size, and age--are important, although this depends on the element studied. Zn and Cu from the spill have entered the food chain of the aquatic birds studied, but Cd, Pb and As have not. There is currently no evidence to suggest that the trace element concentrations measured have reached toxic levels.

Levels of PCBs, PCDDs and PCDFs in commercial butter samples in Spain

Feasibility of three different extraction methods for the simultaneous determination of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in butter is discussed. The method based on liquid-liquid extraction with water of the non fatty solids from butter dissolved in hexane was found to be the most efficient for the determination of the lipid content and the levels of the investigated pollutants. This method was used to evaluate the background levels of PCBs, PCDDs and PCDFs in butters commercially available in Spain. Broad ranges of PCB, specifically, PCDD and PCDF concentrations were found in the different brands analysed. Levels, profiles and patterns of these pollutants in butter were compared with those previously reported for different Spanish dairy products. The toxic tetra-equivalents of 2,3,7,8-TCDD (1-TEQ) averages for PCDDs and PCDFs in the 21 butter samples analysed were 0.41 and 0.70 pg/g fat basis, respectively. These values were similar or lower than those cited in the literature for other countries.

Comparative study of methodologies for the analysis of PCDDs and PDCFs in powdered full-fat milk. PCB, PCDD and PCDF levels in commercial samples from Spain

Feasibility of two different extraction methods involving solid-liquid extraction and Soxhlet extraction, previously used for the determination of lipid contents and PCB levels on powdered full-fat milk, are now examined for simultaneous PCDD/F analysis. The results of this study are consistent with those found for PCBs. The solid-liquid procedure provides the most efficient extraction of both labelled spiked and endogenous PCDD/Fs with the lowest variability. The average recoveries were 101% (R.S.D. = 6.9%) for 13C12-2,3,7,8-TCDD and 95% (R.S.D. = 11%) for 13C12-1,2,3,4,7,8-HxCDD. The R.S.D.s for endogenous 2,3,7,8-PCDD/Fs were in the 9.3-25% range. In addition, this methodology simplified the subsequent clean-up step as it allowed a semi-selective extraction of the apolar lipids from the milk. The proposed method was applied to simultaneous PCB and PCDD/F analyses in different brands of powdered full-fat milks commercially available in Spain. In all cases, very similar PCB and PCDD/F levels were found. Differences among batches from the same manufacturer were even lower. The total i-TEQ average for PCDDs and PCDFs in the 22 powdered full-fat milk samples analysed was 1.87 pg/g fat basis. This value was similar to those found in cow's milk from other European countries.

2,3,7,8-Substituted PCDDs and PCDFs in sea lion (Otaria flavescens) skin biopsies from two South-western Atlantic populations

Congener specific 2,3,7,8-chlorinated PCDDs and PCDFs were determined in skin biopsies taken from sea lions (Otaria flavescens) living in two areas of the South-western Atlantic on the coast of Argentina (Mar del Plata and Punta Bermeja). This is the first report on PCDDs and PCDFs in sea lion skin biopsies from the southern hemisphere. Differences were found in the congener pattern according to the sampling area. Animals living in the polluted area (Mar del Plata harbour) had detectable levels of all seventeen 2,3,7,8-substituted congeners. Sea lions living in a control environment (Punta Bermeja, Patagonia) only exhibited 5 detectable congeners out of all seventeen 2,3,7,8-substituted congeners. However, total levels were low in both colonies studied. These data are consistent with previous work which has indicated that dioxins occur at relatively low levels in marine mammals, possibly due to rapid catabolism or elimination.

Proteolytic processing of a secreted glycoprotein and O-glycosylation of mannoproteins are affected in the N-glycosylation mutant Saccharomyces cerevisiae ldb1

In a previous work [P.I. Mañas, I. Olivero, M. Avalos, L.M. Hernández, Glycobiology, 7 (1997) 487-497], we described the isolation and characterization of the Saccharomyces cerevisiae ldb1 mutant which is affected in several steps of the N-glycosylation of mannoproteins probably due to a malfunction of the Golgi apparatus. Here, we found that two further functions assigned to the Golgi cisternae are also affected in the mutant: proteolytic processing of a secreted protein and O-glycosylation. We found that around 70% of the exoglucanase activity that is secreted into the culture medium by ldb1 bears an extra tetrapeptide in its NH2-terminus due to incomplete proteolytic processing. The O-linked oligosaccharides from ldb1 mnn1 were indistinguishable from those synthesized by the parental strain mnn1. However, when the O-oligosaccharides from the wild type and ldb1 were compared, we found a significant decrease in the tetrasaccharide in the latter, as well as a concomitant increase in the disaccharide, suggesting a defect in the Kre2p/Mnt1p involved in the transfer of the third mannose of these residues.

Levels of PCDDs and PCDFs in farm cow's milk located near potential contaminant sources in Asturias (Spain). Comparison with levels found in control, rural farms and commercial pasteurized cow's milks

Cows milk samples from 12 dairy farms in Spain and 23 samples of pasteurised cows milk were analysed for PCDD/F. Farms located in rural areas without specific dioxin sources (background levels) ranged from 1.3 to 2.47 pg TEQ/g fat basis. These values were slightly lower than those found in milk from the vicinity of potential dioxin emission sources (waste incinerator, chemical and metallurgical industry) and similar to milk near paper industry. The waste incinerator seems to be the emission source with the highest influence on the cows milk gathered in its vicinity. Thus, milk near the waste incinerator exhibited the highest PCDD/F levels, the highest PCDF/PCDD ratio and its congener PCDD pattern showed the highest difference respect to its control point. The PCDD/F average concentrations found in pasteurised commercial milk were lower than those found in raw milk and were comparable to those found in retail milk from other countries.

Effects of ethanol on the inner layers of chick retina during development

Optic nerve hypoplasia is an important malformation of the fetal alcohol syndrome whose teratogenic mechanisms are unknown. In our experimental model we have quantified the concentration of ethanol and acetaldehyde in the retina and vitreous humor of the developing chick. The effect of ethanol alone during retinal development was analyzed by conventional histological techniques and by immunostaining. A single injection of ethanol in the vitelline sac at the beginning of retinal cell differentiation retarded synaptogenesis in the inner plexiform layer and produced abundant ganglion cell death and a sharp diminution of myelinic axons. Our observations could help to explain certain alterations described in children exposed to ethanol during the development of their nervous system.

Variation of PCB congener levels during lactation period and relationship to their molecular structure

The levels of 22 polychlorinated biphenyl (PCB) congeners, including 13 coplanars (non-, mono-, and di-ortho-substituted chlorine) and 9 noncoplanar chirals (tri- and tetra-ortho-substituted chlorine), were measured in mothers milk from different mothers throughout their lactation periods. Important variations were found in the total PCB levels and PCB congener levels. The maximum PCB variations were found during the first weeks of lactation. Of the 22 PCBs analyzed, the most abundant, and those which had the highest variations were PCB-101, 118, 138, 151, 170, and 180, while the least abundant were the PCB-77, 126, 169, and 167, which also showed the lowest variation. Among the nonortho-substituted PCB congeners, PCB-77 was the predominant PCB in three of the four lactation periods studied, while PCB-126 was dominant in the last case. A relationship has been found between the levels and variations of total PCBs in the milk supplied by the different mothers and their dietary habits, weight changes and illness suffered during their pregnancy and lactation. The 22 PCB congeners investigated have been grouped in five categories according to their concentration variations in milk throughout the four different lactation periods. The PCB congeners included in each of the five groups have similar molecular structures. It has been found that coplanarity, number of chlorines and their molecular distribution, and neighbor H atoms were determinant factors in the process of PCB mobilization from the mothers' fats (where it had been able to accumulate throughout her life in the case of her first child) to the breast milk she delivered.

Isolation of new nonconditional Saccharomyces cerevisiae mutants defective in asparagine-linked glycosylation

We describe the isolation and partial characterization of Saccharomyces cerevisiae nonconditional mutants that show defects in N-glycosylation of proteins. The selection method is based on the reduction of affinity for the ion exchanger QAE-Sephadex as a consequence of the decrease in the negative charge of the cell surface. This characteristic reflects a decrease in the incorporation of mannosylphosphate units into the N-linked oligosaccharides of the mannoproteins. The mutants exhibit low affinity for the basic dye alcian blue and for that reason we have called them Idb (low dye binding) mutants. Eight of the complementation groups seem to be new as shown by complementation studies with previously isolated mutants of similar phenotype. Four of the groups showed a significant reduction in the number and/or size of the N-linked oligosaccharides attached to secreted invertase. We have analyzed the N-linked oligosaccharides of Idb1 and Idb2, the mutants that show the most drastic reduction in the affinity for the alcian blue dye. In both cases, the purified endo H-released oligosaccharides from the mannoproteins lacked detectable amounts of phosphate groups as shown by ion exchange chromatography and the 1H NMR spectra. In addition, Ibd1 synthesizes a truncated and unbranched outer chain lacking any alpha (1,2) linked mannoses attached to the alpha (1,6) linear backbone.

Selective elongation of the oligosaccharide attached to the second potential glycosylation site of yeast exoglucanase: effects on the activity and properties of the enzyme

Three exoglucanases (Exgs), ExgIa, ExgIb and Exg325, are secreted by Saccharomyces cerevisiae cells. They share a common protein portion with two potential glycosylation sites (sequons) but differ in the amount of N-linked carbohydrate [Basco, R.D., Muñoz, M.D., Hernández, L.M., Váquez de Aldana, C. and Larriba, G. (1993) Yeast 9, 221-234]. ExgIb contains two short oligosaccharides attached to asparagines (Asn) 165 and 325 of the primary translation product [Hernández, L.M., Olivero, I., Alvarado, E. and Larriba, G. (1992) Biochemistry 31, 9823-9831]. Exg325 carries a single, short oligosaccharide bound to Asn325 whereas ExgIa has at least one large oligosaccharide, since it has not been produced by mutant mnn9. To address the question of the origin of ExgIa, both sequons were individually mutated by substituting Gln for Asn. An ExgIa-like isoenzyme was still secreted by mutant Exg165 but not by mutant Exg325. Additional studies on sequential deglycosylation of ExgIa with endo-beta-N-acetylglucosaminidase H (endo H), the susceptibility of both oligosaccharides to the endoglycosidase, and analysis of the presence of GlcNAc at both asparagine residues after total deglycosylation with endo H, indicated that ExgIa contained two oligosaccharides, a short one bound to Asn165 and a large one bound to Asn325, and, accordingly, originated from ExgIb. The elongation of the second oligosaccharide did not result in a higher stability towards thermal inactivation or unfolding, or in an increased resistance to proteases as compared with ExgIb; however, the affinity of the enzyme towards laminarin decreased by 50%. This site-specific elongation occurred in the oligosaccharide that was less susceptible to endo H, indicating that these properties are determined by different conformational constraints.

Glycosylation of yeast exoglucanase sequons in alg mutants deficient in the glucosylation steps of the lipid-linked oligosaccharide. Presence of glucotriose unit in Dol-PP-GlcNAc2Man9Glc3 influences both glycosylation efficiency and selection of N-linked sites

The major exoglucanase (Exg) from Saccharomyces cerevisiae has a short N-linked oligosaccharide attached to each of the potential glycosylation sites present in the primary translation product. We have studied the Exg glycoforms secreted by alg mutants deficient in the final steps of the assembly of dolichol-P-P-GlcNAc2-Man9-Glc3. These mutants synthesize and transfer to nascent proteins truncated oligosaccharides lacking two (alg8) or three (alg5 and alg6) glucoses. In addition to the enzyme carrying both sugar chains (ExgII), all three mutants secreted underglycosylated forms containing one oligosaccharide attached to either the first (ExgII'1/2) or the second (ExgII1/2) potential glycosylation site, and nonglycosylated enzyme (ExgTuni). As compared with alg5 and alg6, alg8 secreted a higher proportion of ExgII, which was paralleled by a significant drop in the proportion of ExgTuni and, to a lesser extent, of ExgII1/2. The presence of a single glucose attached to Dol-P-P-GlcNAc2-Man9 therefore increases the efficiency of transfer of the that oligosaccharide to the protein acceptor in vivo. Moreover, whereas ExgII'1/2 was never secreted by wild type cells, it was the most abundant underglycosylated form secreted by all three mutants. These mutants are affected in the efficiency at which the individual sequons that are glycosylated, and this suggests a role for the glucotriose unit in the selection of the sequons are to be occupied in glycoproteins synthesized by wild type.

[Early bacterial infections in 103 patients treated with bone marrow transplantation]

PURPOSE

To analyse bacterial infections in the period immediately following bone-marrow transplantation.

PATIENTS AND METHODS

A retrospective study of 174 febrile episodes appearing on 103 patients treated with bone-marrow transplantation in 1990 and 1991 was carried out, special attention being paid to the bacterial infections.

RESULTS

Virtually all patients (100/103) had at least one febrile episode, and its infectious character was documented in 54% of the instances. Gram-positive germs were most commonly present, 85% of the bacteria isolated, and coagulase-negative staphylococci, especially St epidermidis, predominated (60%). Different species of streptococci, mostly of the viridans group, were isolated in 22% of the blood cultures attained in the first febrile episodes. The mortality due to infection in the series as a whole was 4.8%.

CONCLUSIONS

Infections by gram-positive germs, especially coagulase-negative staphylococci, are commonly found among the patients subjected to bone-marrow transplantation. Increased streptococci infections, mostly of the viridans group, are also appreciated. These facts, along with decreased number of gram-negative infections, must be born in mind when designing initial antimicrobial coverage for these patients.

Reduced efficiency in the glycosylation of the first sequon of Saccharomyces cerevisiae exoglucanase leads to the synthesis and secretion of a new glycoform of the molecule

In addition to exoglucanases (EXGs) I and II, old cultures of Saccharomyces cerevisiae secreted into the culture medium a new immunologically-related material that exhibited exoglucanase activity. The new exoglucanase (EXGII1/2) was purified from stationary-phase cultures. It turned out to be a glycoprotein whose protein portion was identical to that of the other two isoenzymes in terms of ionic properties, size, amino acid composition and NH2-terminal sequence (25 residues). Disruption of the structural gene encoding EXGs I and II resulted in a strain unable to secrete all three isoenzymes. EXGII1/2 was indistinguishable in terms of molecular weight from the single intermediate detected during the deglycosylation (mediated by endo H) of EXGII by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Thus, the new isoenzyme contains only one of the two slightly elongated mannan inner cores present in enzyme II. Two intermediates were, however, detected when the deglycosylation of EXGII was monitored by ion-exchange chromatography (high-pressure liquid chromatography). Site-directed mutagenesis indicated that the major intermediate, which eluted at about the same position as enzyme II1/2, corresponded to protein molecules carrying the oligosaccharide attached to the Asn of the second sequon, whereas the minor one carried the oligosaccharide in the first potential glycosylation site. Several lines of evidence indicate that EXGII1/2 is a biosynthetic product resulting from an imbalance between the rate of protein synthesis and the glycosylation capabilities of the glycosylation machinery.

Organochlorine and heavy metal contamination in non-viable eggs and its relation to breeding success in a Spanish population of Lesser Kestrels (Falco naumanni)

Residues of organochlorines, polychlorinated biphenyls (PCBs), and heavy metals (mercury, cadmium, lead, copper and zinc) were measured in unhatched eggs of Lesser Kestrels (Falco naumanni) collected in southern Spain in 1988-1991. Although contaminants were detected in all eggs, the amounts were generally below levels known to have negative effects on reproduction. This is consistent with the relatively high hatching rate (about 80%) in the studied population. The nestling mortality was severe, however, apparently due to starvation. It cannot be discounted that pesticides had an indirect effect on the kestrel's breeding success by reducing the populations of prey.

Study of protein-ligand binding effects by direct chromatographic on-column injection

The direct zonal on-column injection method was applied to a high-performance liquid chromatographic study of pollutant-protein binding interactions in solution. The protein and the protein-ligand complex are excluded on the basis of the size from the diol support, and the free ligand penetrates into the pores and is more retained. The pattern of the ligand elution profile depends on the protein-ligand dissociation constant. This effect was quantitatively analysed by developing a numerical simulation algorithm in which the column is divided into slices of given thickness. The column length, flow-rate and shape of the injection signal are given as input parameters. A global dispersion coefficient accounts for peak broadening. A rapid equilibrium is assumed with the hypothesis that a monovalent ligand interacts with a single binding site on the protein. The interaction of bovine serum albumin with pentachlorophenol was studied, and an apparent dissociation constant for the protein-ligand complex was determined by fitting the theoretical profile to the experimental one. The effect of the acetonitrile content in the solvent was studied. An important decrease of the dissociation constant is observed that affects the chromatographic elution pattern.

Oligosaccharide structures of the major exoglucanase secreted by Saccharomyces cerevisiae

We have determined the structures of the N-linked carbohydrate chains, released by endo H, of exoglucanase II that are secreted by wild-type Saccharomyces cerevisiae and by the mnn1 mnn9 and mnn1 glycosylation mutants. The mnn9 mutation does not significantly affect N-linked oligosaccharides of exoglucanase II since we found almost identical structures in both mutant strains consisting of a slightly enlarged core with the basic structure shown in A (where M = mannose). Most of the molecules (77%) were phosphorylated on one of the starred mannoses (34%) or on both (43%) with a diesterified (alpha M-->P-->) or monoesterified phosphate group. In addition, some of the molecules apparently escape normal processing and retain the alpha-(1-->2)-linked mannose (italicized) and/or the three glucoses that are characteristic of the lipid-linked precursor (structure B). In the wild type, we found the same basic structure but more [formula; see text] than 90% of the molecules were modified with one to four alpha-(1-->3)-linked mannoses, which were absent in the strains bearing the mnn1 mutation (structure C). The proportion of acidic components was similar to that found in the mutants (78%), although, in this case, the monophosphorylated forms were more abundant (50%) than the diphosphorylated ones (28%). Most of the phosphate groups (69%) were diesterified by a disaccharide (alpha M-->3 alpha M-->P-->) instead of the single mannose found when the mnn1 mutation was present. In both mnn1 and wild type 10-15% of the oligosaccharides had an extra alpha-(1-->6)-linked mannose in the outer chain, a structure described in the recently isolated vrg1 mutant [Ballou, L., Hitzeman, R.A., Lewis, M. S., & Ballou, C. E. (1991) Proc. Natl. Acad. Sci. U.S.A. 88, 3209-3212].

[Physician-patient communication and health education]

The aim of the present study was to analyze the content in health education of the patient-physician interview. The study was observational and descriptive. The target population were the patients attending the general practices of the Social Security clinics. With permission of patients and physicians, 53 visits of two general practitioners were recorded on tape. 48 interviews were analyzed with definition of activities (asking, answering, discussing, etc.) and contents (health problems, treatment, health education, etc.). Health education was 10% of the contents, and it was associated with the physician's activity of commenting/instructing and with the patient's activity of commenting/asking.

Two glycosylation patterns for a single protein (exoglucanase) in Saccharomyces cerevisiae

Exoglucanases (beta-glucosidases) I and II secreted into the culture medium by Saccharomyces cerevisiae were purified from cell cultures harvested at the early exponential phase of growth in order to avoid contamination of the second by a new immunologically-related material. The amino acid composition of the purified enzymes was roughly the same. In addition, both exoglucanases exhibited an identical NH2-terminal sequence (50 residues). These results confirm our previous results about the identity of the protein moieties of both enzymes. Exoglucanase I appears to arise by elongation of one or both short oligosaccharides present in enzyme II.

A new Saccharomyces cerevisiae mnn mutant N-linked oligosaccharide structure

We find that the N-linked Man8GlcNAc2- core oligosaccharide of Saccharomyces cerevisiae mnn mutant mannoproteins is enlarged by the addition of the outer chain to the alpha 1----3-linked mannose in the side chain that is attached to the beta 1----4-linked mannose rather than by addition to the terminal alpha 1----6-linked mannose. This conclusion is derived from structural studies on a phosphorylated oligosaccharide fraction and from mass spectral fragment analysis of neutral core oligosaccharides.

A similar protein portion for two exoglucanases secreted by Saccharomyces cerevisiae

Exoglucanase (exo-1,3-beta-D-glucan glycohydrolase, EC 3.2.1.56) activity secreted by Saccharomyces cerevisiae into the culture medium was separated by ion exchange chromatography into two glycoprotein isoenzymes which contributed 10% (exoglucanase I) and 90% (exoglucanase II) towards the total activity. Analysis of the "in vitro" deglycosylated products by polyacrylamide gel electrophoresis under native or denaturing conditions indicated that the protein portions of both exoglucanases exhibited identical mobility, each one consisting of two polypeptides with Mr of 47,000 and 48,000. The same profile was shown by the exoglucanase secreted in the presence of tunicamycin. Antibodies raised against the protein portion of exoglucanase II did react with both native exoglucanases and their deglycosylated products with a pattern indicative of immunological identity. Digestion of the "in vitro" deglycosylated products of both exoglucanases with Staphylococcus aureus V-8 protease or trypsin generated the same proteolytic fragments in each case. Only exoglucanase II was secreted by protoplasts. These and previously reported results indicate that the protein portions of both isoenzymes may be the product of the same gene (or a family of related genes), and that exoglucanase I is a product of enzyme II, modified by a process occurring beyond the permeability barrier of the cell.

Two ionic forms of exoglucanase in yeast secretory mutants

Analysis of exoglucanase activity accumulated by sec mutants from Saccharomyces cerevisiae revealed the presence of two ionic forms of the major exoglucanase (exo II) secreted into the culture medium. From the accumulation pattern of representative sec mutants and the carbohydrate composition it appears that the less acidic form is converted into the more acidic one by addition of one phosphate to one of the oligosaccharide cores as the enzyme progresses through the secretory pathway. Exoglucanase I, the heavier isoenzyme, was not accumulated by the mutants. Accordingly, it should arise from exoglucanase II after the execution point of sec1 mutation.

Accumulation and secretion of exoglucanase activity in yeast secretory mutants

Representative conditional yeast secretory mutants, blocked in transport of secretory and plasma membrane proteins from the endoplasmic reticulum (sec 18), from the Golgi body (sec 7) and in transport of secretory vesicles (sec 1), accumulated exoglucanase, a constitutive yeast activity, when incubated at the restrictive temperature (37 degrees C). Different proportions of the accumulated activity were released by mutant cells under permissive conditions. The presence or absence of cycloheximide during the secretion period made no differences in the results. More than 90% of the internal activity was bound to membrane in wild type cells. However, only the soluble pool underwent changes during the accumulation or secretion periods. The bulk of secretory invertase accumulated by sec 1 was also soluble. By contrast sec 7 and sec 18 accumulated membrane-bound as well as soluble invertase forms and both were secreted in similar proportions in each mutant. More than 90% of the accumulated invertase was secreted at the permissive temperature in sec 18 cells. That percentage was significantly lower for exoglucanase (less than 65%). Concomitantly, invertase accumulated by this mutant exited from the cells with a lower half time (t1/2 = 24 min) than accumulated exoglucanase (t1/2 = 150 min). These results may be interpreted assuming that exoglucanase is exported by a passive flow of the soluble pool.

Accumulation of exoglucanase activity in yeast secretory mutants blocked at the endoplasmic reticulum level

Saccharomyces cerevisiae HMSF-176 (sec 18), a thermosensitive secretory mutant blocked at the endoplasmic reticulum (ER) level, drastically increased its osmotic sensitivity when grown at the restrictive temperature of 37 degrees C in high glucose concentration. This fact led to the erroneous interpretation that glucanases were inactive when localized in the ER. The development of a suitable osmotic stabilizer now indicates that sec 18 accumulates exoglucanase activity. Another ER-blocked mutant behaved in a similar way. All the accumulated exoglucanase was found in a soluble form. By contrast, a significant portion of the accumulated invertase remained in a membrane-bound form.