Effects of the curvature gradient on the distribution and diffusion of colloids confined to surfaces.

The properties and behavior of colloids confined to move on curved surfaces offer a fertile ground for analysis since the geometric constraints induce specific features that are not available in flat spaces. Given their pertinence for biological and physicochemical processes, both with potential useful applications, the development of the concepts and methodology necessary for a deeper understanding of these unconventional systems is indeed an essential pursuit. The present study discusses a general and rigorous algorithm for the implementation of Brownian dynamics simulations that solves underlying difficulties and shortcomings inherent to conventional first-order schemes. Still based on the Ermak-McCammon recipe, our approach complements it with the higher-order geodesical projections of the elementary jumps generated on the associated tangent plane. This strategy, which warrants the locally isotropic propagation of non-interacting particles, is tested with a model system of colloidal particles interacting through a screened Coulomb potential while confined to move on ellipsoidal surfaces. This allows us to measure the effects prompted by the curvature gradient on the static and dynamic properties of this system. The varying curvature thus induces energetically favorable configurations in which the particles maximize their Euclidean distancing by crowding the regions with the largest Gaussian curvature, while withdrawing from those with the lowest. In turn, these inhomogeneous distributions provoke the anisotropic self-diffusion of the confined colloids, which is examined by exploiting the pertinent geodesic radial coordinates. The proficient methods under consideration thus allows dealing with the rich and remarkable new phenomena generated by any distinctive surface geometry.

Structural and dynamic inhomogeneities induced by curvature gradients in elliptic colloidal halos of paramagnetic particles.

Paramagnetic colloidal particles distributed along an ellipse are used as a model system to study the effects of curvature gradients on the structure and dynamics of colloids in curved manifolds. Unlike what happens for circular and spherical systems, in the present case, the equilibrium one-particle distribution function displays inhomogeneities due to the changing curvature along the ellipse. The ensuing effects on the two-body correlations are also analyzed, leading to the observation of anisotropic and long-ranged effects. Another noticeable consequence is the slowing down of the self-diffusion of these particles, which for large eccentricities may induce metastable states; this is evaluated by means of the time-dependent self-distribution.

Development and characterization of 10 microsatellite loci in the giant cardon cactus, Pachycereus pringlei (Cactaceae).

PREMISE OF THE STUDY: Microsatellite primers were developed for the cardon, a giant columnar cactus (Pachycereus pringlei) of the Sonoran Desert, to investigate intraspecific genetic patterns of diversity and population structure. • METHODS AND RESULTS: Using 454 GS-FLX technology and bioinformatics tools, microsatellite primers were successfully identified on 282 reads, including di-, tri-, tetra-, penta-, and hexanucleotides. A set of 10 primers were characterized on 80 individuals collected in two areas of the Baja California peninsula, Mexico. All 10 loci were polymorphic, with a mean of 6.3 alleles per locus and overall levels of observed and expected heterozygosities ranging from 0.41 to 0.59 and from 0.40 to 0.57, respectively. Alleles per individual plant ranged from one to four, suggesting a polyploidal genome. • CONCLUSIONS: These loci should be useful for future investigations of population structure, genetic diversity, and gene flow in the cardon cactus.

Food-service establishment wastewater characterization.

Food-service establishments that use on-site wastewater treatment systems are experiencing pretreatment system and/or drain field hydraulic and/or organic overloading. This study included characterization of four wastewater parameters (five-day biochemical oxygen demand [BOD5]; total suspended solids [TSS]; food, oil, and grease [FOG]; and flow) from 28 restaurants located in Texas during June, July, and August 2002. The field sampling methodology included taking a grab sample from each restaurant for 6 consecutive days at approximately the same time each day, followed by a 2-week break, and then sampling again for another 6 consecutive days, for a total of 12 samples per restaurant and 336 total observations. The analysis indicates higher organic (BOD5) and hydraulic values for restaurants than those typically found in the literature. The design values for this study for BOD5, TSS, FOG, and flow were 1523, 664, and 197 mg/L, and 96 L/day-seat respectively, which captured over 80% of the data collected.

Isolation and characterization of the integration host factor genes of Pasteurella haemolytica.

Using a bacteriophage lambda complementation system in Escherichia coli, we cloned genes encoding subunits of the heterodimeric DNA binding/bending protein, integration host factor, from the bovine pathogen, Pasteurella haemolytica. Complementation of ihfA and ihfB mutations in E. coli demonstrated that the P. haemolytica gene products form functional heterologous heterodimers. The ihfA and ihfB genes encode polypeptides predicted to be 99 and 93 amino acids long, respectively, and are very similar to integration host factor subunits from other Gram-negative bacteria, although phylogenetic analysis indicated that the P. haemolytica sequences are distantly related to those from other bacteria. Most significant amino acid differences were restricted to the amino-terminal domains of the predicted peptides.

The restriction-modification system of Pasteurella haemolytica is a member of a new family of type I enzymes.

Genes encoding the type I restriction-modification (R-M) system of the bovine pathogen, Pasteurella haemolytica, have been identified immediately downstream of a locus that encodes a transcriptional activator of P. haemolytica leukotoxin expression. Type I enzymes are encoded by three genes called hsdM, hsdS and hsdR, and have fallen into three groups, called Ia, Ib and Ic. HsdS provides a sequence recognition function which in concert with HsdM forms an active methyltransferase (MTase). Inclusion of the HsdR subunit in the complex creates an active restriction endonuclease (ENase) capable of cleaving unmethylated target DNA. The P. haemolytica hsdMSR genes were mapped using transposon Tn10d-Cam insertions, and bacteriophage restriction and modification assays in Escherichia coli. We determined the nucleotide sequences of hsdM, hsdS and hsdR, and observed that the deduced amino acid (aa) sequences were very similar to predicted R-M subunits in the respiratory pathogen, Haemophilus influenzae. Phylogenetic comparisons of all known Hsd aa sequences placed the P. haemolytica and H. influenzae proteins into a new group which we labeled the Type Id R-M family. Expression of the P. haemolytica R-M genes in E. coli was inefficient and is likely to be a consequence of the unusual codon usage in P. haemolytica genes.

Cytologic effects of photodynamic therapy in body fluids.

Photodynamic therapy (PDT) has been used in phase I clinical trials at the National Institutes of Health for the treatment of malignancies disseminated within the peritoneal and pleural cavities. Review of records revealed 18 patients who were treated with PDT between April 1988-June 1993. Sixty-five pleural and peritoneal fluids, 22 pre- and 43 post-PDT, were available for evaluation. Mesothelial cell changes seen post-PDT included: increased nuclear-to-cytoplasmic ratios in 7/18 (39%), cytomegaly in 9/18 (50%), and multinucleation in 12/18 (67%), with Touton-like giant cells in 3/18 (17%). Additional changes noted post-PDT comprised histiocytic aggregates in 9/18 patients (50%), with granuloma-like clusters in 3/18 (17%), acute and chronic inflammation in 13/18 (72%), and eosinophilia in 8/18 (44%). Residual tumor was present in 7/18 (39%) patients post-PDT. In 2 patients with malignant mesothelioma, benign mesothelial cells with cytologic changes post-PDT were difficult to distinguish from malignant cells. Mesothelial cell changes following PDT, specifically increased nuclear-to-cytoplasmic ratios and cytomegaly, should be recognized to avert false-positive diagnoses of tumor. In patients with malignant mesothelioma, and less commonly with adenocarcinoma, benign mesothelial cells with changes secondary to PDT may be difficult to distinguish from tumor cells.

Anatomical study of the blood supply to the skin in rhytidectomy.

This study was undertaken to evaluate the blood supply to the facelift flap by identifying the perforating arteries in the anterior facial region, which is preserved during the undermining of the flap. We have called this medial zone the pedicle area of the flap. Eleven pairs of musculocutaneous perforator arteries supplying the facelift flap were identified, all of them emerging from three main arterial trunks: the facial, the superficial temporal, and the ophthalmic arteries. A rich anastomotic network connected all the vessels; however, we were able to group this network into five basic forms including the ipsilateral and contralateral external and internal carotid arteries. We found these anastomotic links to be constant. We propose that this anatomical feature of the face provides for adequate blood supply even when certain regions have been altered by previous dissection, injury, or congenital deformity. This study confirms previous anatomical findings but also adds specific information regarding the blood supply to the facelift flap that will allow this procedure to be carried out with maximum safety and effectiveness.

[Detection of non-insulin-dependent diabetes mellitus in asymptomatic adults]. / Detección de diabetes mellitus no insulinodependiente en adultos asintomáticos.

A total of 1,011 clinically asymptomatic adults older than 20 years of age, with a minimal fasting of one hour, were screened for diabetes mellitus. This group was selected from a community medical service. The presence of diabetes in first degree relatives (parents, brothers/sisters and children) was investigated by interrogation of the subjects. Weight, height, and the waist and hip perimeters were measured, and the body mass index and the waist/hip ratio were calculated. Obesity was present in 26% of the population and 35.6% had a relative with diabetes mellitus, but 53.8% were younger than 40 years. A capillary blood sample was taken and glucose was measured by a reflectometer glucometer. Individuals with blood glucose levels of 160 mg/dL or higher were appointed for a fasting venous blood sample and glucose was analyzed using the glucose oxidase method. If the glucose levels were > 140 mg/dL, a second fasting venous blood sample was taken 1-2 weeks later, if both results were > 140 mg/dL a diagnosis of diabetes mellitus was established; otherwise it was considered non diagnostic for diabetes mellitus. A total of 17 were detected with > 160 mg/dL by the glucometer and 12/17 persons were diagnosed with diabetes mellitus (1.2%). No person younger than 30 years was detected (n = 307), but 3/237 were detected in the thirty years group (1.26% for this group) and 9 persons were older than 40 years, 1.2% of the total group. Capillary glucose measurements may be used for screening of populations selecting those who require to be submitted to diagnostic tests.

Expression of the Pasteurella haemolytica leukotoxin is inhibited by a locus that encodes an ATP-binding cassette homolog.

Multicopy and single-copy chromosomal fusions between the Pasteurella haemolytica leukotoxin regulatory region and the Escherichia coli beta-galactosidase gene have been constructed. These fusions were used as reporters to identify and isolate regulators of leukotoxin expression from a P. haemolytica cosmid library. A cosmid clone, which inhibited leukotoxin expression from multicopy and single-copy protein fusions, was isolated and found to contain the complete leukotoxin gene cluster plus additional upstream sequences. The locus responsible for inhibition of expression from leukotoxin-beta-galactosidase fusions was mapped within these upstream sequences, by transposon mutagenesis with Tn5, and its DNA sequence was determined. The inhibitory activity was found to be associated with a predicted 440-amino-acid reading frame (lapA) that lies within a four-gene arginine transport locus. LapA is predicted to be the nucleotide-binding component of this transport system and shares homology with the Clp family of proteases.

Anatomical study of the blood supply in the human shoulder region.

The blood supply of the shoulder muscles, ligaments and joint capsule was investigated by injection of silicone rubber into the arteria subclavia of postmortem cases. We show that the a. suprascapularis forms important anatomoses with other arteries in the region and is of greater importance for the blood supply of the rotator cuff as hitherto believed. We also describe the a. subcoracoidea as a so far unknown branch of the a. axillaris.

[Cardiac myxoma, diagnostic methods and curative surgery. Report of 5 cases]. / Mixoma cardiaco, metodos diagnósticos y cirugía curativa. Informe de 5 casos.

We report five patients with Myxomas of the left atrium studied by catheterization and/or Echocardiography between november 1976 and october 1978. Four patients were operated immediately with extracorporeal circulation which confirmed the diagnosis. The last patient died before surgical intervention due to a severe hepatorenal syndrome and extensive pulmonary infection. Another patient died postoperatively on the second day due to irreversible pulmonary hypertensión. The remaining three patients are asymptomatic (average 28 months after surgery). Reviewing the diagnostic methods, particularly the Echocardiogram, we found that it is a good diagnostic tool, making catheterization with the risks of myxomatous embolization unnecessary. Furthermore, the Echo facilitates simple and economic observation for the detection of relapses. Finally, broad and careful surgical management most be emphasized in order to avoid transoperative emboli, tumoral dissemination, and latent relapses, mediated by the greater use of filters and a broad resection of the implantation pedicule.

[Mitral valve replacement, results in 160 patients]. / Reemplazo valvular mitral, resultados en 160 pacientes.

The results of 163 mitral valve replacement from 160 patients since August 1972 til August 1977 are presented, this is the second communication in Mexico related to mechanical mitral prosthesis. 95 patients were females and 55 males. With ages from 8 to 57 years, average 34; the 13% were child or teenagers. In 67% there were a clear background of rheumatic fever; 50% cardiac insufficiency and 19% previous mitral surgery from 8 months to 12 years before. 94% were class III or IV (N.Y.H.A.) and only 6% in I or II. Surgery was indicated according symptoms and hemodynamic data, 98% were catheterized. 26 Starr-Edwards and 137 Bjork-Shiley prosthesis were implanted in mitral position; in 112 cases only the mitral valve was substituted, in 41 cases a tricuspid procedure was done and in another 10 cases the aortic valve was also changed. The postoperative complications were: arrhythmies 32%; low cardiac output in 21%; infections 9%. Operative mortality in the isolated mitral replacement was 12%; in those cases with mitral-aortic or mitro-tricuspic lesions have been 33% in the first three years and 25% in the last three years. The long-term follow-up in 130 survivors is 29 months; 81% of them are actually in class I, 16% in class II and 3% in class III. The literature is reviewed and the facts responsive for the improved results are analyzed; special importance is given to the temporal external cardiac pacing in the management of the postoperative arrhythmies. Mitral valve replacement is considered as a good palliative procedure to the functional and socio-economical long-term rehabilitation in the survivors.