Both morphological and molecular characters support speciation of South American siskins by sexual selection

South American siskin radiation was studied by both mitochondrial cytochrome b (mt cyt b) DNA sequencing and homologous phenotypic characters; the latter were coded separately according to sex. Mixed phenetic and molecular (total evidence) dendrograms were constructed and the corresponding analyses suggest that speciation started in the South American siskin group with a north to south separation (Carduelis notata/C. barbata) along the Andean spine. A second split may have taken place around the Peruvian Andean mountains, corresponding to the present distribution pattern of C. olivacea. The most recent speciation events seem to have occurred in three sister species pairs: (i) C. xanthogastra/C. atrata, (ii) C. magellanica/C. yarrellii, (iii) C. cucullata/C. crassirostris. Accumulation of consistent characters in both morphological and molecular data at the basal nodes of the dendrograms indicate that speciation events occurred within a short period of time. Our data also suggest that speciation probably occurred by sexual selection through female mating choice in this radiation. Additionally, studies of variable amino acid residues in the mt cyt b molecule show that the three variable amino acids found are placed in the mitochondrial transmembrane region, which is also part of the hypervariable region in mammals. Each of the three amino acid changes occur in each of the three postulated evolutionary groups.

Simplified method for the detection of apo(a) isoforms

Apolipoprotein a, is a high molecular weight glycoproteic component of Lp(a), a molecule associated with coronary arterial disease. Apo(a) exhibits considerable size heterogeneity due to variable repetitions of the carbohydrate-containing structural unit, termed kringle. There are five different kringle forms and 10 different kringle 4 types. Apo(a) polymorphism and molecular weight depend on the number of copies of kringle 4 type 2. In this paper we describe a modified 3.75% and 6% discontinuous polyacrylamide gel system and Western-blot technique that shortness the assay time and improves the identification of apo(a) isoforms with a theoretical error of less than 1 kringle. The assay uses a standard curve prepared with five different recombinant apo(a) molecules, detected up to 50 ng of protein in Lp(a), showed a maximal resolution of 2 kringles and, with the use of third degree polynominal regression analysis, had an error of 0.01275. The inter-assay coefficient of variation was 1.7, 2, and 1.4 for the 14 K, 18 K, and 22 K phenotypes, whereas the intra-assay coefficient of variation was 0.32%, 0.18%, and 0.17%, respectively. It is possible that this modified method will diminish the number of putative null alleles so far detected in various studies, but most of all, we are certain that it can be of use in epidemiological studies due to its ease of use, speed, low cost, and enhanced number of samples that can be tested.

The Old World sparrows (genus Passer) phylogeography and their relative abundance of nuclear mtDNA pseudogenes

The phylogenetic relationships of genus Passer (Old World sparrows) have been studied with species covering their complete world living range. Mitochondrial (mt) cyt b genes and pseudogenes have been analyzed, the latter being strikingly abundant in genus Passer compared with other studied songbirds. The significance of these Passer pseudogenes is presently unclear. The mechanisms by which mt cyt b genes become pseudogenes after nuclear translocation are discussed together with their mode of evolution, i.e., transition/transversion mitochondrial ratio is decreased in the nucleus, as is the constraint for variability at the three codon positions. However, the skewed base composition according to codon position (in 1st position the percentage is very similar for the four bases, in 2nd position there are fewer percentage of A and G and more percentage of T, and in 3rd codon position fewer percentage of G and T and is very rich in A and C) is maintained in the translocated nuclear pseudogenes. Different nuclear internal mechanisms and/or selective pressures must exist for explaining this nuclear/mitochondrial differential DNA base evolutive variability. Also, the phylogenetic usefulness of pseudogenes for defining relationships between closely related lineages is stressed. The analyses suggest that the primitive genus Passer species comes from Africa, the Cape sparrow being the oldest: P. hispaniolensis italiae is more likely conspecific to P. domesticus than to P. hispaniolensis. Also, Passer species are not included within weavers or Estrildinae or Emberizinae, as previously suggested. European and American Emberizinae sparrows are closely related to each other and seem to be the earliest species that radiated among the studied songbirds (all in the Miocene Epoch).

Phylogeography of crossbills, bullfinches, grosbeaks, and rosefinches

Mitochondrial cytochrome b (cyt b) from 24 Carduelini species including crossbills, bullfinches, grosbeaks, rosefinches, and other related, but not conclusively classified species, was sequenced. These sequences were also compared with all the available sequences from the genera Carduelis, Serinus, and Passer. Phylogenetic analyses consistently gave the same groups of finches and the calculated divergence times suggest that speciation of the studied species occurred between 14 and 3 million years ago (Miocene-Pliocene), appearing before the Passer, Carduelis, and Serinus genera. Pleistocene glaciations may have been important in sub-speciation. Crossbills are integrated within the genus Carduelis, and within redpolls; the common crossbill shows subspeciation with Loxia japonica in the Pleistocene epoch. Pinicola enucleator groups together with bullfinches and is probably the ancestor of the group. Hawfinch is only distantly related to the studied groups, and might either represent an isolated genus or be related to the New World genus Hesperiphona. The grosbeak genera Eophona and Mycerobas are clearly sister groups, and species belonging to the former might have given rise to Mycerobas species. The isolated (in classification) Uragus sibiricus and Haematospiza sipahi are included within the genus Carpodacus (rosefinches); Carpodacus nipalensis is outside the genus Carpodacus in the molecular analyses and might be an isolated species or related to the genus Montifringilla.

Hypothyroidism provides resistance to reperfusion injury following myocardium ischemia

A growing body of evidence has demonstrated that reperfusion injury may be mediated, in part, by mitochondrial Ca2+ overload that promotes non-selective permeability of the inner membrane. In this regard it is known that mitochondria from hypothyroid rats are resistant to membrane damage as induced by Ca2+. The purpose of this study was to evaluate the sensitivity of hearts from hypothyroid rats, to the damage by reperfusion, after an ischemic period of 5 min. The results were compared with those from control and hyperthyroid rats. Hypothyroidism was established by surgical removal of the thyroid gland; in turn hyperthyroidism was induced after a daily injection of 2 mg/kg of 3,5,3'-triiodothyronine for 4 days. ECG tracings from hypothyroid rats showed a total absence of post-reperfusion arrhythmias conversely to what was observed in control and hyperthyroid rats. The release of creatine kinase and aspartate amino transferase to the plasma in hypothyroid rats was found to be lower than that found in hyperthyroid and euthyroid rats. The histological studies showed that myocardial fibers from hypothyroid rats were in good condition and retained their striae and a remarkable near absence of edema was clearly observed.

alpha-cyclodextrin extracts diacylglycerol from insect high density lipoproteins

alpha-Cyclodextrins are water-soluble cyclic hexamers of glucose units with hydrophobic cavities capable of solubilizing lipophiles. Incubating alpha-cyclodextrin with high density lipophorin from Manduca sexta or Bombyx mori resulted in a cloudy, turbid solution. Centrifugation separated a pale yellowish precipitate. Thin-layer chromatography analysis of the lipid extract of the precipitate showed that the major lipid was diacylglycerol, while KBr density gradient analysis of the supernatant demonstrated the presence of a lipid-depleted very high density lipophorin. Transfer of diacylglycerol from lipophorin to cyclodextrin was specific to alpha-cyclodextrin and was not observed with beta- or gamma-cyclodextrins. pH had no effect on diacylglycerol transfer to alpha-cyclodextrin. However, the transfer was strongly dependent on the concentration of alpha-cyclodextrin and temperature. Increasing the concentration of alpha-cyclodextrin in the incubation mixture was associated with the formation of increasingly higher density lipophorins. Thus, at 20, 30, and 40 mm alpha-cyclodextrin, the density of B. mori lipophorin increased from 1.107 g/ml to 1.123, 1. 148, and 1.181 g/ml, respectively. At concentrations greater than 40 mm, alpha-cyclodextrin had no further effect on the density of lipophorin. alpha-Cyclodextrin removed at most 83;-87% of the diacylglycerol present in lipophorin. Temperature played an important role in altering the amount of diacylglycerols transferred to alpha-cyclodextrin. At 30 mm alpha-cyclodextrin, the amount of diacylglycerol transferred at different temperatures was 50% at 4 degrees C, 41% at 15 degrees C, 20% at 28 degrees C, and less than 3% at 37 degrees C. We propose that diacylglycerol transfers to alpha-cyclodextrin via an aqueous diffusion pathway and that the driving force for the transfer is the formation of an insoluble alpha-cyclodextrin-diacylglycerol complex.

HLA genes in Arabic-speaking Moroccans: close relatedness to Berbers and Iberians

The gene profile of Arabic-speaking Moroccans has been compared with those of other Mediterranean populations in order to provide additional information about the history of their origins. Our HLA data suggest that most Moroccans are of a Berber (Imazighen) origin and that Arabs who invaded North Africa and Spain in the 7th century A.D. did not substantially contributed to the gene pool; however, they imposed their advanced culture and their religion. Present-day Egyptians are also related to Moroccan Berbers and this supports an ancient Saharan origin for part of the present-day Mediterraneans, particularly for the Arabic-speaking ones (also Algerians) and also for the older substratum of Mediterranean people.

Kinematics of the wrist. Evidence for two types of movement

We enrolled 34 normal volunteers to test the hypothesis that there were two types of movement of the wrist. On lateral radiographs two distinct patterns of movement emerged. Some volunteers showed extensive rotation of the lunate with a mean range of dorsiflexion of 65 degrees, while others had a mean range of 50 degrees. The extensive rotators were associated with a greater excursion of the centre of articulation of the wrist. It is suggested that dynamic external fixation of a fracture of the distal radius carries with it the risk of stretching the ligaments or causing volar displacement at the site of the fracture.

The results at ten years of the Insall-Burstein II total knee replacement. Clinical, radiological and survivorship studies

We reviewed the outcome of 146 Insall-Burstein II total knee replacements carried out in 121 patients over a period of nearly four years in a general orthopaedic unit. At a mean follow-up of ten years, 94 knees in 78 patients were available for review. Six patients (7 knees) were lost to follow-up and 37 (45 knees) had died. The clinical outcome using the scoring system of the Hospital for Special Surgery (HSS) was excellent or good in 79% of patients, fair in 14% and poor in 7%. The mean preoperative HSS score was 31, improving to 79 at the latest review. Using the newer rating system of the Knee Society, the mean score at ten years was 87 and the mean functional score 56. The arc of flexion improved from a mean preoperative value of 88 degrees to 100 degrees. The 18 patients who had had a previous high tibial osteotomy were analysed separately and were found to have benefited equally from the operation. Nine prostheses were revised, giving a cumulative survival rate of 92.3% at ten years. Radiological evaluation of 104 radiographs showed radiolucent lines around ten tibial components, none of which required revision. Anterior knee pain was a significant problem.

The results at ten years of the Insall-Burstein II total knee replacement

We reviewed the outcome of 146 Insall-Burstein II total knee replacements carried out in 121 patients over a period of nearly four years in a general orthopaedic unit. At a mean follow-up of ten years, 94 knees in 78 patients were available for review. Six patients (7 knees) were lost to follow-up and 37 (45 knees) had died.

The clinical outcome using the scoring system of the Hospital for Special Surgery (HSS) was excellent or good in 79% of patients, fair in 14% and poor in 7%. The mean preoperative HSS score was 31, improving to 79 at the latest review. Using the newer rating system of the Knee Society, the mean score at ten years was 87 and the mean functional score 56. The arc of flexion improved from a mean preoperative value of 88° to 100°. The 18 patients who had had a previous high tibial osteotomy were analysed separately and were found to have benefited equally from the operation. Nine prostheses were revised, giving a cumulative survival rate of 92.3% at ten years. Radiological evaluation of 104 radiographs showed radiolucent lines around ten tibial components, none of which required revision. Anterior knee pain was a significant problem.

A serological survey of leptospirosis in sheep in Chile

In order to investigate exposure to Leptospira spp. in sheep in the Xth Region in the south of Chile, 629 ovine serum samples were collected from 11 convenience selected sheep farms, using within farm random sampling. The sera collected were examined for antibodies to the following serovars; icterohaemorrhagiae, autumnalis, hardjo, pomona, ballum, and canicola, using the Microscopic Agglutination Test. Ten out of eleven flocks had sheep which were seropositive for at least one Leptospira spp. Positive tests, the majority at low titres, were obtained from 36/629 (5.7%) of all the serum samples tested. The most frequently detected serovars were, in descending order: icterohaemorrhagiae, autumnalis and hardjo. The greatest proportion of positive samples came from sheep which were over 30 months old.

[Virulence plasmid in Yersinia enterocolitica O:3 of murine origin]

BACKGROUND

Pathogenic strains of Yersinia enterocolitica harbor a virulence plasmid of 45-48 megadalton that can be detected using different techniques. Rodents are important reservoirs of Y enterocolitica.

AIM

To investigate the carrier status of Y enterocolitica in murine rodents.

MATERIAL AND METHODS

Two hundred sixty-one mice and rats were captured in rural and urban areas of Valdivia. Y enterocolitica was cultured from viscera and fecal homogenates. Virulence plasmids were detected using crystal violet binding.

RESULTS

Thirteen Y enterocolitica strains were isolated from 11 rodents. Ten strains belonged to the biotype 1 and three to the biotype 4, serotype O:3. The most frequently infected rodent species were R norvergicus (20%), followed by A longipilis (11%), A olivaceus (2%) and O longicaudatus (2%).

CONCLUSIONS

Rodents, and specially the domestic rat, can be an important source of Y enterocolitica infection for human and susceptible animal species.

Learning and stabilization of altruistic behaviors in multi-agent systems by reciprocity

Optimization of performance in collective systems often requires altruism. The emergence and stabilization of altruistic behaviors are difficult to achieve because the agents incur a cost when behaving altruistically. In this paper, we propose a biologically inspired strategy to learn stable altruistic behaviors in artificial multi-agent systems, namely reciprocal altruism. This strategy in conjunction with learning capabilities make altruistic agents cooperate only between themselves, thus preventing their exploitation by selfish agents, if future benefits are greater than the current cost of altruistic acts. Our multi-agent system is made up of agents with a behavior-based architecture. Agents learn the most suitable cooperative strategy for different environments by means of a reinforcement learning algorithm. Each agent receives a reinforcement signal that only measures its individual performance. Simulation results show how the multi-agent system learns stable altruistic behaviors, so achieving optimal (or near-to-optimal) performances in unknown and changing environments.

Hemolysins and verotoxin (VT) in enteric Escherichia coli isolated from pigs

One hundred and three E. coli strains isolated from the intestinal contents of pigs were examined for hemolysis and verotoxin production on Vero monolayer cells. Hemolysins were produced by 18 (17.5%) strains;--hemolysin was produced by 6 strains of which 4 belonged to serotype O149:K91, K88ac;--hemolysin was produced by 8 strains which could no be serotyped; 1 strain produced-hemolysin and possessed fimbrial antigens K88; the remaining 3 strains were enterohemolytic and VT producers. Among the 85 non-hemolytic strains, 11 showed some antigenic properties. Only 3 could be serotyped (O64:K 'V142'; O157:K 'V17' and O149:K91); 4 had fimbrial antigens K88 and 1 strain was K99, and 3 possessed capsular antigen (K89). According to these results it is possible to conclude that both hemolytic and non-hemolytic E. coli strains could be pathogenic.

Specialization in multi-agent systems through learning

Specialization is a common feature in animal societies that leads to an improvement in the fitness of the team members and to an increase in the resources obtained by the team. In this paper we propose a simple reinforcement learning approach to specialization in an artificial multi-agent system. The system is composed of homogeneous and non-communicating agents. Because there is no communication, the number of agents in the team can easily scale up. Agents have the same initial functionalities, but they learn to specialize and so cooperate to achieve a complex gathering task efficiently. Simulation experiments show how the multi-agent system specializes appropriately so as to reach optimal (or near-to-optimal) performance in unknown and changing environments.

Vascular reactivity and effect of serum in a rat model of hypertriglyceridemia and hypertension

It has not been definitely established whether elevated circulating triglyceride-rich lipoproteins constitute an independent risk factor for hypertension, atherosclerosis, myocardial infarction, and coronary heart disease. To investigate some aspects of the physiopathology of this lipid metabolism abnormality, a model of experimental hypertriglyceridemia and hypertension in rats was studied. The animals received commercially refined sugar (30%) in their drinking water during a period of 12 to 17 weeks. Monthly measurements of blood pressure and serum triglycerides were taken during and at the end of the treatment period; the levels of glucose and insulin were also determined. The blood, the aorta, and mesenteric artery were removed. Age- and weight-matched controls were used. The reactivity of the isolated vessels to norepinephrine and acetylcholine and the effect of control and hypertriglyceridemic serum on the same preparations were investigated. In hypertriglyceridemic rats, the response to acetylcholine in the tissues was reduced compared to the control arteries; the hypertriglyceridemic serum elicited contractions that were greater than those induced by control serum. The impaired response of hypertriglyceridemic tissue to the vasodilator and the effect of the hypertriglyceridemic serum on artery contraction suggest that the overall dyslipidemia could contribute to a chronic increase in vascular tone and, consequently, to hypertension.

Renal tubular acidosis in children with vesicoureteral reflux

PURPOSE

We evaluated renal tubular acidosis in children with primary vesicoureteral reflux.

MATERIALS AND METHODS

We studied 18 children 4 to 15 years old to determine age at onset, reflux intensity, and renal scars and volume as possible associated factors of renal tubular acidosis. Patients had normal glomerular filtration rates and no urinary infections for the last 12 weeks, and they had not undergone urological surgery. Urine acidification and alkalization tests were done, and the Mann-Whitney U test was used to assess differences between the groups with and without renal tubular acidosis.

RESULTS

A total of 14 patients had unilateral and 4 had bilateral reflux, which varied in severity. All children except 2 had renal scarring. Bilateral renal volume was smaller in the renal tubular acidosis group. Nine patients had distal renal tubular acidosis, including 4 with short stature.

CONCLUSIONS

Several patients with vesicoureteral reflux had renal tubular acidosis and some had growth failure. Grades of reflux and renal scarring were similar in patients with and without renal tubular acidosis. A single evaluation of reflux is of slight value for predicting future functional tubular impairment, and the duration of reflux and other associated factors may be more important. Renal tubular acidosis was the main explanation for growth failure in these patients.

[Comparison of 4 microscopy techniques for the diagnosis of leptospirosis in wild rodents in a rural area of Valdivia, Chile]

Kidneys of six different species of 93 wild rodents captured in the rural area of Valdivia (Chile) were simultaneously examined for leptospira infection by means of Levaditi silver stain, dark ground microscopy in wet smears, and immunofluorescence and immunoperoxidase techniques using pooled antiserum against hardjo and pomona serovars. Leptospira was shown to be present in 40 (43.0%) rodents. They were detected in five of the six species: Akodon olivaceus, Akodon longipilis, Rattus rattus, Oryzomis longicaudatus and Mus musculus. Levaditi's technique detected the highest number of positive samples (67.5%) and the dark field microscopy the lowest (32.5%). The detection of leptospira in the kidneys of these wild rodents suggests that their urine may play an important role in the dissemination of leptospirosis in this area of Valdivia.

Effects of delayed recanalization of an occluded acute myocardial infarction-related artery using coronary angioplasty on late potentials

BACKGROUND

Recent evidence suggests that late reperfusion of an occluded infarct-related artery after an acute myocardial infarction may reduce the frequency of subsequent arrhythmic events. Late mechanical reperfusion by percutaneous transluminal coronary angioplasty (PTCA) under these circumstances has a high success rate. The present study was performed to test the hypothesis that the late mechanical restoration of anterograde flow in an occluded infarct artery after an acute myocardial infarction causes a resolution of late potentials.

METHODS

Twenty subjects (10 men, one woman; aged 32-77 years) suffering a first acute myocardial infarction, with signal-averaged electrocardiographic (ECG) recordings and a severely occluded infarct-related artery, were prospectively identified.

RESULTS

Eighteen patients underwent successful PTCA of the occluded artery 6-32 days after a first acute myocardial infarction. Late potentials were observed in 14 patients 5-22 days after the infarction. A follow-up signal-averaged ECG was performed 1-8 days later. In the subgroup of 12 patients with successful reperfusion and an abnormal signal-averaged ECG before PTCA, seven (58.3%) showed resolution of the late potentials at follow-up; in these patients the filtered QRS duration showed a significant reduction (112.1 +/- 14.2 to 96.7 +/- 12.7 ms, P = 0.02), the root-mean-square voltage increased (9.8 +/- 6.5 to 33.1 +/- 15.5 microV, P = 0.017), and the duration of low-amplitude signals < 40 microV decreased after angioplasty (46.3 +/- 11.0 to 28.5 +/- 6.5 ms, P < 0.022). In contrast, two patients with late potentials before PTCA and unsuccessful reperfusion had no significant changes in signal-averaged ECG.

CONCLUSIONS

In some patients with an acute myocardial infarction, late mechanical reperfusion of the culprit vessel may reduce the incidence of abnormalities on the signal-averaged ECG. Whether this will improve long-term survival has yet to be confirmed in a large trial.