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At least 109 records · Page 6Linked to original sources
PubMed1992

Automated detection of the tongue surface in sequences of ultrasound images.

An image processing system has been developed for a Macintosh II personal computer. It is designed to process sequences of sagittal tongue sections that are digitized in real time and stored in standard tagged image file format (TIFF). The successive processing steps are: (a) a low-pass filter for noise reduction, (b) a resampling of the sector of interest in polar coordinates, (c) a matched filter (vertical differentiator) for the enhancement of the tissue/air interface in the surface region of the tongue, and (d) an extraction of border points by searching for an optimal radial path along the angular dimension. This latter task is achieved by dynamic programming, which has the following advantages. First, due to the use of a global criterion to guide the detection, it is very robust. Second, as a result of certain restrictions of the allowable transitions, the extracted contours are smooth. Finally, the method permits the specification of particular predefined contour points. This system was implemented in a program that can handle image sequences in a fully automatic mode. Results obtained using ultrasound data are presented.

Humans↗
PubMed1990

Conformational study of the cembranoid sarcophytol A, a potent anti-tumor-promoter.

Conformational analysis of the marine cembranoid sarcophytol A (1a), a potent anti-tumor promoter, was carried out using a newly introduced molecular mechanic and molecular dynamic program Discover. Four minimum-energy conformations were derived, in accordance with a previous results of the epoxidation of 1a, which afforded 7R,8R/7S,8S- and 11R,12R/11S,12S-epoxide pairs. The most stable conformation was the one having C-19 and C-20 directed opposite to C-18, with respect to the average plane of the fourteen-membered ring. X-Ray crystallography of sarcophytol A alpha-methoxy-alpha-trifluoromethylphenylacetate (1c) was carried out simultaneously. This confirmed the 14S absolute configuration of 1a but the conformation of crystalline 1c did not correspond to any of the four minimum-energy conformers of 1a.

Crystallization↗
PubMedDate not supplied

[A rapid method of searching for homology of nucleic acid sequences].

A new method of the homology search between DNA sequences was suggested. This method may be used to find extensive and not strong homologies with point mutations and deletions. The computer time to compare sequences is less than dynamic program algorithms at least by four orders of magnitude. It makes possible to use the method for homology search all over the nucleotide bank by personal computers. Some results of homology search are presented.

Algorithms↗
PubMed1987

Induction of common patterns of polypeptide synthesis and phosphorylation by calcium and 12-O-tetradecanoylphorbol-13-acetate in mouse epidermal cell culture.

Terminal differentiation can be induced in cultured basal cells by either increasing the Ca2+ level in the medium from 0.05 to 1.4 mM or by exposure to the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). If Ca2+ and TPA act by a common mechanism, then a common pattern of protein synthesis and/or phosphorylation would be expected. Computer-assisted analysis of radioactively labeled polypeptides separated by two-dimensional-polyacrylamide gel electrophoresis was utilized to study protein synthesis and phosphorylation. Within 1 h of increasing the Ca2+ level in the medium, the synthesis of 57 polypeptides was altered by 2-fold or more. Similarly, exposure to TPA for 1 h affected the synthesis of 106 polypeptides. Sixteen polypeptides were affected by both Ca2+ and TPA; the synthesis of nine was increased and seven was decreased, with changes in the same direction for both effectors. By 4 h, the synthesis of 32 polypeptides was similarly modulated by both Ca2+ and TPA. Only one polypeptide which was increased at 1 h was still elevated at 4 h. These results suggest that a common dynamic program of protein synthesis, likely to be related to terminal keratinocyte differentiation, is induced by both Ca2+ and TPA. Overall phosphorylation of epidermal proteins was increased after 30 min of TPA treatment, but was not increased by Ca2+ at this time. Keratin polypeptides were heavily phosphorylated in low Ca2+ medium, but the level or pattern of phosphorylation of these proteins was not altered by either Ca2+ or TPA. Although phosphorylation of a minor polypeptide (pI 5.1/Mr 45,000) was increased 2-3-fold by both Ca2+ and TPA, most of the specific protein phosphorylation changes induced in keratinocytes by Ca2+ and TPA appear to be unique. Thus, if protein phosphorylation is an early signal for epidermal differentiation by each effector, only a single apparent common substrate is involved and multiple kinases are activated. Alternatively, substrate specificity of a single kinase may be differentially altered by each effector.

Animals↗
PubMed1985

Redistribution of arterial blood flow in metastases-bearing livers after infusion of degradable starch microspheres.

Changes in intrahepatic arterial blood flow after intraarterial injection of degradable starch microspheres (DSM) were studied in four patients undergoing hepatic arterial chemotherapy. All four livers contained metastases, three from colorectal cancer and one from melanoma. Using a CT scanner with a dynamic program, 8 mm liver sections were studied in each patient before and after the DSM infusion (180(-6) in 3 min). Density plots were obtained from 12 tumoral and 12 parenchymal areas after 5 ml push arterial injections of nonionic contrast medium. The areas under the curves (ID) were calculated. The ID after DSM infusion was reduced by 94% in a single hyperdense colorectal metastasis and by a mean of c. 82% in ten parenchymal areas. By contrast, nine hypodense colorectal metastases showed an average ID decrease of c. 156%. The ID of two melanoma metastases was reduced after DSM (-48% and -68%), while the ID of two matched parenchymal areas showed an approximately similar degree of increase (+36% and +64%). Since ID after contrast injection can be assumed to be a function of blood volume, mutual changes of parenchymal and tumoral blood flow appear to take place in metastases-bearing liver after arterial infusion of DSM. This phenomenon may be of diagnostic and therapeutic value for intraarterial chemotherapy of liver tumors.

Antineoplastic Agents↗
PubMedDate not supplied

[Tasks in planning biological experiments].

The paper describes certain cases of using mathematical methods in the planning of biological experiments. The paper presents an algorithm of the distribution of the experimental data based on dynamic programming. The paper discusses an application of computer-aided calculations for the formation of homogeneous groups of experimental and control tests.

Animals↗
PubMed2026

From immature to mature epithelium: unveiling structural dynamics and transcriptional programs in rainbow trout intestinal barrier.

The intestinal epithelium is crucial for nutrient absorption, immune defense, and barrier function in farmed fish. However, the molecular mechanisms underlying its development and maturation in salmonids remain poorly characterized, hindering our ability to address pervasive gut health challenges in aquaculture. In this study, we use the RTgutGC cell line to implement an epithelial maturation model with the aim of characterizing the global transcriptional program in rainbow trout (Oncorhynchus mykiss). We evaluated in vitro culture conditions to generate a polarized epithelial barrier with high transepithelial electrical resistance (TEER = 75.8 Ω × cm2), low permeability (6.2 × 10-6 cm/s), and well-defined apical specializations, including microvilli-like structures and clusters of these structures (brush border). Comparative transcriptomic profiling between immature (7 days post-seeding, dps) and mature (28 dps) epithelia revealed 3,817 differentially expressed genes (DEGs). Functional enrichment analysis showed that maturation was characterized by the downregulation of proliferative and ribosomal pathways and the concerted upregulation of processes critical for barrier function, including transmembrane transport, proteolysis, cell adhesion, extracellular matrix organization, and tight junction assembly. We identified a core set of 60 genes indicators of epithelial maturation, encompassing solute transporters (slc26a6, slc43a2), tight junction proteins (tjp1, cldn1, cldn3, cldn5, cldn18, among others), and structural components essential for microvilli formation and polarization (cdhr5b, pard6a). By integrating ultrastructural, functional, and transcriptomic data, this study established a framework for future mechanistic investigations into gut development and maturation in vitro. This set of mature epithelium indicators has diverse applications, such as the design of nutritional and pharmacological interventions to improve gut health and resilience in farmed fish.

Animals↗
PubMed1992

FOCUS: a program for analyzing molecular dynamics simulations, featuring digital signal-processing techniques.

FOCUS is a program for analyzing molecular dynamics simulations. It enables the researcher to monitor structural and energetic properties during the trajectory, and to calculate the corresponding statistical averages, correlation functions and Fourier transforms. In addition to these conventional methods, the program also utilizes novel methods based on digital signal-processing techniques to characterize the various motions. The characteristic frequencies in the system are revealed by the frequency distribution function g(v), which is calculated from the Fourier transform of the atomic coordinates. A filtering technique is employed to remove uninteresting motion (e.g., high-frequency bond stretching) while retaining and focusing on important motion (e.g., low-frequency conformational motion). The filtering technique enables fast display of slow events without getting a blurry or jittery picture due to the high-frequency motions. Another new way for analyzing the motion is by extracting "characteristic modes" and associated frequencies. This yields a pictorial description of the oscillatory motions in a manner analogous to normal mode analysis.

Acetamides↗
PubMedDate not supplied

DIABLOG: a simulation program of insulin-glucose dynamics for education of diabetics.

This paper presents a dialogue computer program, DIABLOG, for the education of diabetic patients with insulin therapy. Through mathematical modelling of glucose-insulin dynamics this program is able to simulate glucose and insulin profiles of a 24 h period and display them graphically as curves. The subjects could vary the carbohydrate content of meals, the injection time and dose of short-acting and intermediate-acting insulin and could switch to insulin pump therapy. For a first evaluation 22 patients with insulin-dependent diabetes mellitus tested the program and their comments were recorded by a questionnaire. The results indicate a good acceptance of the program even by patients with no previous computer experience. Further suggestions by the patients will be discussed as well.

Blood Glucose↗
PubMed1991

Molecular dynamics simulation on a network of workstations using a machine-independent parallel programming language.

Molecular dynamics simulations investigate local and global motion in molecules. Several parallel computing approaches have been taken to attack the most computationally expensive phase of molecular simulations, the evaluation of long range interactions. This paper develops a straightforward but effective algorithm for molecular dynamics simulations using the machine-independent parallel programming language, Linda. The algorithm was run both on a shared memory parallel computer and on a network of high performance Unix workstations. Performance benchmarks were performed on both systems using two proteins. This algorithm offers a portable cost-effective alternative for molecular dynamics simulations. In view of the increasing numbers of networked workstations, this approach could help make molecular dynamics simulations more easily accessible to the research community.

Algorithms↗
PubMed1992

Molecular dynamics simulation on a network of workstations using a machine-independent parallel programming language.

Molecular dynamics simulations investigate local and global motion in molecules. Several parallel computing approaches have been taken to attack the most computationally expensive phase of molecular simulations, the evaluation of long range interactions. This paper reviews these approaches and develops a straightforward but effective algorithm using the machine-independent parallel programming language, Linda. The algorithm was run both on a shared memory parallel computer and on a network of high performance Unix workstations. Performance benchmarks were performed on both systems using two proteins. This algorithm offers a portable cost-effective alternative for molecular dynamics simulations. In view of the increasing numbers of networked workstations, this approach could help make molecular dynamics simulations more easily accessible to the research community.

Algorithms↗
PubMed1990

Dynamic training and circulating levels of corticotropin-releasing factor, beta-lipotropin and beta-endorphin in rheumatoid arthritis.

The study aimed at evaluating the effects of a dynamic training program on circulating levels of corticotropin-releasing factor (CRF), beta-lipotropin (beta-LPH), and beta-endorphin (beta-EP) in 8 patients (5 females and 3 males, aged 39-65 years) with classical/definite rheumatoid arthritis (RA). Blood samples were collected immediately before, in the middle of, and after a 6-week high-intensity training period as well as after a subsequent 1-year period of low-intensity training. In addition, baseline data were obtained 3 weeks before the start of the training program. Use of multivariate analyses of variance, and of analyses of variance of contrast variables, indicated a short-term effect of the high-intensity training program for beta-EP with increased levels (P less than 0.05) between the 3rd and the 6th weeks, no significant differences being obtained for CRF or beta-LPH here. Corresponding analyses with regard to the combined high and low-intensity training program revealed CRF (P less than 0.01), and beta-LPH (P less than 0.01) levels to increase over time, no long-term effect being found for beta-EP. Despite the intensity of the dynamic training program, no change was found in pain experience as measured on a visual analogue scale.

Adult↗
PubMed1990

Muscle function in rheumatoid arthritis. Assessment and training.

The conclusions can be summarized as follows: experienced problems of muscle function were reported in about 80% of RA and OA patients for whom there was involvement of large joints of the lower extremities; RA and OA patients did not differ as to experienced problems of muscle strength, endurance and balance/coordination; problems of muscle function were correlated with functional tests of muscle strength but not with those of endurance and balance/coordination; problems of muscle strength were found to correlate with LE-ADL, whereas problems of endurance and balance/coordination were not found to correlate with the latter; the translated and slightly modified version of the HAQ questionnaire appeared to possess a high degree of reliability and validity in assessing disability in patients with RA under Swedish conditions; a quantitative battery of tests for the evaluation of standing balance on a computerized force platform was found to be satisfactorily reliable and to correlate in healthy subjects with most of the functional tests employed; in healthy subjects, standing balance appeared to be related not only to age but also to sex, males and older age groups showing greater postural sway than females and persons of younger age groups; compared with healthy subjects, RA subjects showed significantly greater postural sway, differences being greatest for those tests representing a relatively high level of difficulty; dynamic training for six weeks appeared to provide RA patients with a greater increase in physical capacity of the lower extremities than did static training, the gains thus obtained still being present after an additional three-month period; the effectiveness of the dynamic training programs did not vary with the degree of supervision of training by a physiotherapist, i.e. of 12 visits or 4 being made at the health care centre; despite the intensity of the dynamic training-program employed with RA patients, no increase in pain experience or disease activity was found during the training-period; during short-term high-intensity training a significant increase in circulating beta-EP was found between the 3rd and 6th weeks of training, no increase in CRF and beta-LPH being present; following a long-term low-intensity training period, a significant increase of CRF and beta-LPH was found, no similar increase being noted for beta-EP.

Arthritis, Rheumatoid↗
PubMed1991

Rehabilitation and biomechanics.

In the area of rehabilitation and biomechanics, several articles divided into five categories, including therapeutic heat, foot and ankle orthotics, exercise in elderly arthritis patients, muscle strengthening in rheumatoid arthritis, and arthroplasty and immobilization are reviewed. Superficial heat was demonstrated to increase intra-articular temperature, and therefore, may be detrimental. On the other hand, local deep microwave hyperthermia appears to have potential therapeutic benefits. The role and effectiveness of foot orthotic devices are reviewed. The problem and treatment of forefoot varus is emphasized. A new technique of measuring subpedal pressure in the shoe is presented, demonstrating reduced foot pressures by certain types of footwear. Rheumatoid arthritis and osteoarthritis wee present in 23% of a nursing home population, but were a substantial factor for placement in only 15%. However, this group had higher pain scores, depended more on wheelchair use, and was more likely to have significant functional limitations. Exciting new data on strengthening the quadriceps in the frail elderly, whose mean age was 90.2 years, are reviewed. The relationship of quadriceps muscle strength and maximum voluntary strength as a function of age and gender and the effects of an endurance training program in 15 physically compromised nursing home residents is discussed. A static and a dynamic training program for rheumatoid arthritis patients were compared. The dynamic group significantly increased muscle strength, endurance, and aerobic capacity as compared to the static group, without any increase in disease activity. The results further showed that a home program was beneficial. Interesting data presented show that using a Cybex isokinetic dynamometer (Lumex, Bayshore, NY) test was reliable for normal control and for rheumatoid arthritis patients who were stronger.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗