Showing papers by "University at Buffalo published in 1989"

Sequence and tissue distribution of a second protein of hepatic gap junctions, Cx26, as deduced from its cDNA.

Abstract: While a number of different gap junction proteins have now been identified, hepatic gap junctions are unique in being the first demonstrated case where two homologous, but distinct, proteins (28,000 and 21,000 Mr) are found within a single gap junctional plaque (Nicholson, B. J., R. Dermietzel, D. Teplow, O. Traub, K. Willecke, and J.-P. Revel. 1987. Nature [Lond.]. 329:732-734). The cDNA for the major 28,000-Mr component has been cloned (Paul, D. L. 1986. J. Cell Biol. 103:123-134) (Kumar, N. M., and N. B. Gilula. 1986. J. Cell Biol. 103:767-776) and, based on its deduced formula weight of 32,007, has been designated connexin 32 (or Cx32 as used here). We now report the selection and characterization of clones for the second 21,000-Mr protein using an oligonucleotide derived from the amino-terminal protein sequence. Together the cDNAs represent 2.4 kb of the single 2.5-kb message detected in Northern blots. An open reading frame of 678 bp coding for a protein with a calculated molecular mass of 26,453 D was identified. Overall sequence homology with Cx32 and Cx43 (64 and 51% amino acid identities, respectively) and a similar predicted tertiary structure confirm that this protein forms part of the connexin family and is consequently referred to as Cx26. Consistent with observations on Cx43 (Beyer, E. C., D. L. Paul, and D. A. Goodenough. 1987. J. Cell Biol. 105:2621-2629) the most marked divergence between Cx26 and other members of the family lies in the sequence of the cytoplasmic domains. The Cx26 gene is present as a single copy per haploid genome in rat and, based on Southern blots, appears to contain at least one intron outside the open reading frame. Northern blots indicate that Cx32 and Cx26 are typically coexpressed, messages for both having been identified in liver, kidney, intestine, lung, spleen, stomach, testes, and brain, but not heart and adult skeletal muscle. This raises the interesting prospect of having differential modes of regulating intercellular channels within a given tissue and, at least in the case of liver, a given cell.

Somatostatin analogues inhibit growth of pancreatic cancer by stimulating tyrosine phosphatase

Abstract: Several analogues of somatostatin were examined in the Mia PaCa-2 human pancreatic cancer cell line for their ability to promote tyrosine phosphatase activity affecting the receptors for the epidermal growth factor. The inhibition of growth of the Mia PaCa-2 cells in culture was also evaluated to determine the mechanism of action of somatostatin analogues and their relative effectiveness in inhibiting cancer growth. Of the analogues tested D-Phe-Cys-Tyr-D-Trp-Lys-Val-Cys-Trp-NH2 (RC-160) caused the greatest stimulation of tyrosine phosphatase activity. Analogue D-Phe-Cys-Tyr-D-Trp-Lys-Val-Cys-Thr-NH2 (RC-121) had less effect but was more potent than somatostatin-14. Analogue D-Phe-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr(ol) (SMS 201-995) produced no significant dephosphorylation. The analogues displayed the same order of activity in assays on growth inhibition of Mia PaCa-2 cells in cultures. Analogue (SMS-201-995) caused virtually no tyrosine phosphatase stimulation or growth inhibition in this cancer cell line, although it possesses a much higher antisecretory activity than somatostatin-14 in normal tissues. These observations indicate that somatostatin and some of its analogues can act as growth inhibitors in cancer cells through the activation of tyrosine phosphatase. These data reinforce the view that somatostatin analogue RC-160 and related compounds could be used for treatment of pancreatic cancer.

Analysis of textual images using the Hough transform

Abstract: The analysis of images of printed pages of text is considered. Since printed text can be viewed as textured line, the use of the Hough transform for detecting straight lines is proposed as an analysis tool. Methods for handling several discretization problems that arise in mapping the rectangular image space to the (ρ, Θ) accumulator array are described. Several applications of analyzing the accumulator array are proposed. They include detecting the text skew angle, determining the signature of a text line so as to accept or reject a block as containing only text, using profile analysis to segment text into lines, and determining whether a textual block is rightside-up or otherwise.

Alcohol and human sexuality: review and integration.

Abstract: Summarizes physiological findings and reviews the psychological experimental literature investigating the relationship between alcohol and human sexuality. Specifically, the authors attempt to reconcile the apparent contradictions found in the effects of alcohol on male and female sexual responding. The review concludes (a) that alcohol disinhibits psychological sexual arousal and suppresses physiological responding, the former effect being stronger at lower doses of alcohol and the latter effect at higher doses; (b) that although suppression is strictly pharmacological in nature, disinhibition appears to be both pharmacological (the result of cognitive impairment) and psychological (the result of socially learned expectancies); and (c) that expectancies and cognitive impairment can disinhibit separately or jointly. A cursory glance at the experimental literature investigating the relation of alcohol to human sexuality reveals an array of results, many of which bear no apparent relationship to each other and which sometimes appear to be flatly contradictory. We propose that these results can be integrated in a manner that resolves ostensible contradiction. This integration attempts to explicate the overlap of two inherently complex areas of study, namely, sexuality and alcohol. Alcohol is intricately woven into the fabric of most, if not all, human cultures. Its consumption provides mystical trance, holy communion, celebration and consolation, social acceptance and condemnation, prowess and impotence, languor and lust. Indeed, there is scarcely a human activity that has not been said to be both impoverished and improved by the addition of alcohol. Sexuality is, if anything, more tangled in the mesh of human experience than alcohol. Even if one could consider sexual functioning as a physical phenomenon divorced from all social entanglements (a dubious possibility, at best), it is a highly variable and intricate process, both between and within persons. In a utopian world, sex might be simply a means of recreation and reproduction. In our world, however, sex is a vital factor in all social phenomena, which in turn exert powerful influences on all sexual behavior, from masturbation to marriage. That there is a relationship between alcohol and sexuality is a matter of consensus. The two are paired throughout poetry, prose, history, and belief. Alcohol is considered to be a tool of seduction, a measure of manhood, a giver of sexual courage, This article was completed by the first author in partial fulfillment of the requirements for the PhD in clinical psychology, under the supervision of the second author. Preparation of this review was supported in part by funds from the National Institute on Alcohol Abuse and Alcoholism by way of a New Investigator Research Award (No. AA06776) to the second author.

Classification of newspaper image blocks using texture analysis

Abstract: An important step in the analysis of images of printed documents is the classification of segmented blocks into categories such as half-tone photographs, text with large letters, text with small letters, line drawings, etc. In this paper, a method to classify blocks segmented from newspaper images is described. It is assumed that homogeneous rectangular blocks are first segmented out of the image using methods such as run-length smoothing and recursive horizontal/vertical cuts. The classification approach is based on statistical textural features and feature space decision techniques. Two matrices, whose elements are frequency counts of black-white pair run lengths and black-white-black combination run lengths, are used to derive texture information. Three features are extracted from the matrices to determine a feature space in which block classification is accomplished using linear discriminant functions. Experimental results using different block segmentation results, different newspapers, and different image resolutions are given. Performance and speed with different image resolutions are indicated.

Large Linguistic Areas and Language Sampling

Abstract: Le phenomene de parente areale peut s'etendre jusqu'a un continent, ne peut donc etre neglige au profit d'une typologie " preferentielle " des langues du monde. L'auteur propose une methode d'echantillonnage

Heterogeneity of virulence among strains of Bacteroides gingivalis.

Abstract: The ability of fresh isolates of B. gingivalis to establish abscesses in the mouse model was studied by comparing them with established laboratory strains of B. gingivalis. Eight fresh isolates obtained from plaque associated with periodontal disease and grown under similar conditions as established strains were injected subcutaneously on the back of the mouse. All of these strains produced secondary lesions on the abdomen. Septicemia was associated with seven of the strains. Two commonly used laboratory strains, W50 and W83, also produced secondary lesions and septicemia. Five other laboratory strains produced only localized abscesses. On histologic examination, the strains that produced disseminated disease showed invasion of connective disease by individual bacteria that were not in clumps. The strains that produced localized abscesses were characterized by growing in colonies or clumps in the abscess cavity. Four synthetic enzyme substrates were examined to determine whether the differences between invasive and non-invasive strains were due to differences in proteolytic enzyme production. No differences in enzyme production could be demonstrated with the selected substrates.

Effects of aluminum and magnesium antacids and ranitidine on the absorption of ciprofloxacin

Abstract: The effect of an antacid (Maalox) and ranitidine administration on the absorption of ciprofloxacin was evaluated in healthy male volunteers who were enrolled in three separate studies. Each study was designed at a three- or four-period crossover and included the administration of 750 mg ciprofloxacin alone as a control treatment. Treatments that were evaluated included the administration of ciprofloxacin 5 to 10 minutes, 2 hours, 4 hours, and 6 hours after a single 30 ml dose of antacid; the administration of antacid 2 hours after ciprofloxacin was given; and the administration of ciprofloxacin 2 hours after a 200 mg ranitidine tablet. Administration of antacid within 4 hours before ciprofloxacin dose resulted in a significant decrease in ciprofloxacin absorption (p less than 0.05). Percentages of relative bioavailability compared with control values were 15.1%, 23.2%, and 70% for the 5 to 10 minute, 2 hour, and 4 hour antacid pretreatments, respectively. Administration of antacid 6 hours before or 2 hours after the ciprofloxacin dose did not affect absorption. Ranitidine did not alter ciprofloxacin absorption. Antacids that contain magnesium and aluminum salts may reduce the absorption of ciprofloxacin. The extent of this interaction appears to increase as the time between administration of the two drugs decreases. Ranitidine is suggested as an alternative to antacids for patients receiving treatment with ciprofloxacin.

Ligating the ductus arteriosus before birth causes persistent pulmonary hypertension in the newborn lamb.

Abstract: We determined whether closing the ductus arteriosus of the fetal lamb several d before birth would cause persistent pulmonary hypertension after birth. Six experimental fetuses who had their ductus arteriosus ligated 3-17 d before delivery, three control fetuses who had sham ligation of the ductus arteriosus 14 d before delivery, and six control fetuses who had no prenatal surgery were delivered by cesarean section between 138 and 144 d of gestation. Each was instrumented to measure pulmonary and systemic arterial pressures and pulmonary blood flow. Each newborn lamb was ventilated with room air during the first 45 min after birth and then with decreasing amounts of inspired oxygen from 100 to 9%. Pulmonary arterial pressure decreased significantly when ventilation was begun in the control lambs but not in the lambs who had their ductus arteriosus ligated before delivery. Throughout the experiment, pulmonary arterial pressure and total pulmonary resistance were significantly higher, and pulmonary blood flow was significantly lower in the lambs who had their ductus arteriosus ligated before delivery. In two of them, pulmonary arterial pressure was greater than or equal to systemic arterial pressure, even during ventilation with 100% oxygen. This animal preparation provides a method of investigating persistent pulmonary hypertension in the newborn lamb and may provide insight into an etiology of the syndrome of persistent pulmonary hypertension of the newborn.

Evaluation of intravenous ciprofloxacin in patients with nosocomial lower respiratory tract infections. Impact of plasma concentrations, organism, minimum inhibitory concentration, and clinical condition on bacterial eradication.

Abstract: • Fifty patients with gram-negative lower respiratory tract infections were treated with intravenous ciprofloxacin to evaluate efficacy and safety. Relationships between individual pharmacokinetics and clinical and bacteriologic outcome were studied. Ciprofloxacin concentrations in plasma were determined by high-performance liquid chromatography. Respiratory secretion cultures were obtained daily to determine the eradication day of the infecting organism. Susceptibility (minimum inhibitory concentration) to ciprofloxacin and other antimicrobials was determined using standard microdilution techniques. The mean age of the patients was 70 years. They had multiple underlying diseases, and two thirds of them were ventilator dependent at entry. Approximately 50% of the patients had failed previous treatment for the same infections. Patients infected with Enterobacteriaceae or Haemophilus influenzae with minimum inhibitory concentrations of less than 0.25 mg/L responded well to intravenous ciprofloxacin therapy (200 mg every 12 hours). The organisms were eradicated from sputum cultures usually within 1 day after ciprofloxacin therapy was started. Most clinical failures occurred in patients who were infected with Pseudomonas aeruginosa and had multiple underlying diseases. Pseudomonas aeruginosa was isolated from 10 patients with pneumonia, 2 patients with lung abscess, and 1 patient with bronchiectasis. The Pseudomonas isolate acquired resistance during ciprofloxacin treatment in 7 patients with pneumonia and in all of the remaining 3 patients. We conclude that ciprofloxacin is safe and effective at a dosage of 200 mg administered intravenously every 12 hours for nosocomial lower respiratory tract infections caused by Enterobacteriaceae or Haemophilus species. Many patients who had failed previous antibiotic treatment for Enterobacteriaceae infections had good clinical response to ciprofloxacin therapy. Studies using either higher dosages of ciprofloxacin or combination therapy should be conducted to determine if acquired resistance can be avoided in Pseudomonas infections. ( Arch Intern Med . 1989;149:2269-2273)

Spatial decision support systems: a research agenda

Abstract: Definitions of geographic information systems often focus on the capture, storage, manipulation, analysis and display of spatial data - implying that geographic information systems implicitly are designed to support spatial decision-making. For many spatial problems, however, geographic information systems do not support decision-making effectively: analytical modelling capabilities are lacking and system designs are not flexible enough to accommodate variations in either the context or the process of spatial decision-making. One response to these needs is the development of spatial decision support systems. We draw a distinction between geographic information systems and spatial decision support systems in terms of system design, the types of problem to which each can be applied, and the decision-making processes supported. We classify the impediments to both the design and implementation of spatial decision support systems and outline a research agenda to address these problems. -Authors

Cross-Sectional Comparisons of the Mathematical Performance of Children with Learning Disabilities Are We on the Right Track Toward Comprehensive Programming?

Abstract: This study examines the mathematical performance of 220 children from 8 years through 17 years of age diagnosed as having learning disabilities. Student records were searched for data indicating performance on standardized test instruments relating to mathematics. Data for the Woodcock-Johnson Psycho-Educational Achievement Battery math subtests and for the IQ scores from the Wechsler Intelligence Scale for Children-Revised were obtained. Comparisons were made among children at different ages and among specific age clusters. Primary attention was directed toward calculations and applications of math concepts and principles. Developmental patterns across the ages studied were discovered. Implications for long-term comprehensive programming are presented.

Age related differences in learning to use a text-editing system

Abstract: The increased use of computer technology in most occupations means that many middle-aged and older workers who lack computer experience will need to acquire skills to interact with this technology. This study examined age-group differences in learning to use a text-editing system. One hundred and thirty-five females ranging in age from 25 to 70 participated in the study. They received training under one of three training conditions: instructor-based, online or manual-based. Age differences were assessed by comparing performance on criterion tasks. Results indicated significant differences among the groups in learning success, younger learners being the most successful. There were no significant age by training interactions. The findings indicate a need to develop more effective training strategies to teach older learners to use computer technologies. They also indicate the need for changes in system design because computer applications are difficult for novice users to learn.

Stacking faults in the kaolin-group minerals: defect structures of kaolinite

Abstract: Previous studies of the defect structure of kaolinite have examined samples having a restricted level of defects. This study examined nine kaolinite samples having a large diversity of defect contents, as indicated by Hinckley indexes ranging from 1.44 to 0.18. The samples were chosen so as to cover this range in as regular a manner as possible. The types and abundances of the defects were determined by examining the X-ray powder diffraction profiles for the 02,11 and 20,13 bands. The diffraction intensities were measured by counting for a fixed time in steps of 0.01°2θ. Analysis of these diffraction profiles indicated that (1) the major defect is the existence of a translation between adjacent layers, which is not the usual t→1 (approximately a/3), but is related to that translation by the pseudo-mirror plane coincident with the long diagonal of the unit cell; (2) the existence of a few C layers among the B layer stacking is a minor defect; (3) many of the samples could be accurately modeled only by assuming the existence of two kaolinite phases; (4) the existence of only a few C layers in some samples does not support the idea of a continuous series from kaolinite to dickite through disordered intermediates; and (5) the Hinckley indexes of several samples depend on the relative proportions of the two types of kaolinite in the mixture. p ]The nine kaolinite samples fall into three groups: those having a low to moderate abundance of defects (Hinckley index > 0.43) are mixtures of two types of kaolinite (one almost free of defects, the other richer in defects); those having low Hinckley indexes (0.43 to 0.18) are single phases with different proportions of defects; and those which contain a single type of kaolinite, unlike the others in the nature of the interlayer translations and the greater abundance of C layers. The agreement between calculated and observed X-ray diffraction profiles is excellent for all specimens, except one sample (from Charentes) for which the fit is acceptable but not perfect.

Seismic response of steel frame structures with added viscoelastic dampers

Abstract: The feasibility of using viscoelastic (VE) dampers to mitigate earthquake-induced structural response is studied in this paper. The properties of VE dampers are briefly described. A procedure for evaluating the VE damping effect when added to a structure is proposed in which the damping effect of VE dampers is incorporated into modal damping ratios through an energy approach. Computer simulation of the damped response of a multi-storey steel frame structure shows significant reduction in floor displacement levels.

Gender Differences in Comparisons and Entitlement: Implications for Comparable Worth

Abstract: This article addresses the role of comparison processes in the persistence of the gender wage gap, its toleration by those most disadvantaged by it, and resistance to comparable worth as a corrective strategy. It proposes that the gender segregation of jobs and the underpayment of women and women's jobs lead women and men to use different comparison standards when evaluating what they are entitled to receive in terms of pay for work. I argue that gender differences in entitlement contribute to toleration of injustice among underpaid female workers, foster cultural beliefs regarding what is appropriate pay for male and female workers, and serve as sources of potential bias in job evaluation plans. In addition, a variety of structural, cognitive, and affective factors encourage individuals to compare within groups, to regard ingroup members as the most relevant and legitimate comparative referents, and to inhibit the outgroup comparisons that lie at the heart of the comparable worth strategy.

Social Contagion and Multiplexity Communication Networks as Predictors of Commitment and Role Ambiguity

Abstract: This research compares two contrasting perspectives of social contagion processes associated with the organizational outcome variables of commitment and role ambiguity in organizations. The two perspectives are structural equivalence (which focuses on the positions of individuals in social networks) and cohesion (which focuses on an individual's direct communication contacts). It was hypothesized that structural equivalence would be more associated with role ambiguity and that commitment would be more associated with cohesion. The relationship between these variables and multiplex content networks was also studied. It was hypothesized that commitment was a much more broadly based concept in the sense that a number of functional content networks systematically relate to it. On the other hand, role ambiguity was hypothesized to be more closely associated with uniplex networks, especially those related to job duties and organizational goals. While there were exceptions, generally the research results supported the hypotheses relating to multiplexity. The hypotheses that structural equivalence was more associated with role ambiguity and that commitment was more associated with cohesion also were supported in this research.