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Biomedical subjects

J Lien

Publications and source records attributed to J Lien.

At least 19 recordsLinked to original sources
PubMed2000

Tissue-engineered valved conduits in the pulmonary circulation.

OBJECTIVE: Bioprosthetic and mechanical valves and valved conduits are unable to grow, repair, or remodel. In an attempt to overcome these shortcomings, we have evaluated the feasibility of creating 3-leaflet, valved, pulmonary conduits from autologous ovine vascular cells and biodegradable polymers with tissue-engineering techniques. METHODS: Endothelial cells and vascular medial cells were harvested from ovine carotid arteries. Composite scaffolds of polyglycolic acid and polyhydroxyoctanoates were formed into a conduit, and 3 leaflets (polyhydroxyoctanoates) were sewn into the conduit. These constructs were seeded with autologous medial cells on 4 consecutive days and coated once with autologous endothelial cells. Thirty-one days (+/-3 days) after cell harvesting, 8 seeded and 1 unseeded control constructs were implanted to replace the pulmonary valve and main pulmonary artery on cardiopulmonary bypass. No postoperative anticoagulation was given. Valve function was assessed by means of echocardiography. The constructs were explanted after 1, 2, 4, 6, 8, 12, 16, and 24 weeks and evaluated macroscopically, histologically, and biochemically. RESULTS: Postoperative echocardiography of the seeded constructs demonstrated no thrombus formation with mild, nonprogressive, valvular regurgitation up to 24 weeks after implantation. Histologic examination showed organized and viable tissue without thrombus. Biochemical assays revealed increasing cellular and extracellular matrix contents. The unseeded construct developed thrombus formation on all 3 leaflets after 4 weeks. CONCLUSION: This experimental study showed that valved conduits constructed from autologous cells and biodegradable matrix can function in the pulmonary circulation. The progressive cellular and extracellular matrix formation indicates that the remodeling of the tissue-engineered structure continues for at least 6 months.

Animals↗
PubMed2000

Endocrine effects of the podophyllotoxine derivative drug CPH 82 (Reumacon) in patients with rheumatoid arthritis.

CPH 82 is a non-steroid antirheumatic drug containing two benzylidenated podophyllotoxin glucosides with no affinity for the glucocorticoid receptor. Treatment with CPH 82 as single drug therapy significantly decreased serum and urinary cortisol and cortisol metabolites, serum adrenal androgens and urinary androgen metabolites, plasma ACTH and serum interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha), and increased serum levels of sex hormone-binding globulin (SHBG). Significant positive correlations were found between serum TNF-alpha and plasma ACTH and between serum IL-6 and TNF-alpha on the one hand and serum and urinary cortisol and cortisol metabolites on the other. The initial action of CPH 82 on adrenal steroidogenesis may be a reduction in cytokine levels due to the drugs' antiinflammatory effect. This causes decreased ACTH stimulation, resulting in a reduced adrenocortical steroid secretion. Accumulation of the drug in the adrenal cortex may also affect adrenal steroidogenesis. The elevated SHBG levels may be caused by a weak estrogenic activity of the drug.

Adrenocorticotropic Hormone↗
PubMed1999

Tissue engineering of autologous aorta using a new biodegradable polymer.

BACKGROUND: Ovine pulmonary valve leaflets and pulmonary arteries have been tissue-engineered (TE) from autologous cells and biodegradable polyglycolic acid (PGA)-polyglactin copolymers. Use of this cell-polymer construct in the systemic circulation resulted in aneurysm formation. This study evaluates a TE vascular graft in the systemic circulation which is based on a new copolymer of PGA and polyhydroxyalkanoate (PHA). METHODS: Ovine carotid arteries were harvested, expanded in vitro, and seeded onto 7-mm diameter PHA-PGA tubular scaffolds. The autologous cell-polymer vascular constructs were used to replace 3-4 cm abdominal aortic segments in lambs (group TE, n = 7). In a control group (n = 4), aortic segments were replaced with acellular polymer tubes. Vascular patency was evaluated with echography. All control animals were sacrificed when the grafts became occluded. Animals in TE group were sacrificed at 10 days (n = 1), 3 (n = 3), and 5 months (n = 3). Explanted TE conduits were evaluated for collagen content, deoxyribonucleic acid (DNA) content, structural and ultrastructural examination, mechanical strength, and matrix metalloproteinase (MMP) activity. RESULTS: The 4 control conduits became occluded at 1, 2, 55, and 101 days. All TE grafts remained patent, and no aneurysms developed by the time of sacrifice. There was one mild stenosis at the anastomotic site after 5 months postoperatively. The percent collagen and DNA contents approached the native aorta over time (% collagen = 25.7%+/-3.4 [3 months] vs 99.6%+/-11.7 [5 months], p < 0.05; and % DNA = 30.8%+/-6.0 [3 months] vs 150.5%+/-16.9 [5 months], p < 0.05). Histology demonstrated elastic fibers in the medial layer and endothelial specific von Willebrand factor on the luminal surface. The mechanical strain-stress curve of the TE aorta approached that of the native vessel. A 66 kDa MMP-2 was found in the TE and native aorta but not in control group. CONCLUSIONS: Autologous aortic grafts with biological characteristics resembling the native aorta can be created using TE approach. This may allow the development of "live" vascular grafts.

Animals↗
PubMed1999

Automated face analysis by feature point tracking has high concurrent validity with manual FACS coding.

The face is a rich source of information about human behavior. Available methods for coding facial displays, however, are human-observer dependent, labor intensive, and difficult to standardize. To enable rigorous and efficient quantitative measurement of facial displays, we have developed an automated method of facial display analysis. In this report, we compare the results with this automated system with those of manual FACS (Facial Action Coding System, Ekman & Friesen, 1978a) coding. One hundred university students were videotaped while performing a series of facial displays. The image sequences were coded from videotape by certified FACS coders. Fifteen action units and action unit combinations that occurred a minimum of 25 times were selected for automated analysis. Facial features were automatically tracked in digitized image sequences using a hierarchical algorithm for estimating optical flow. The measurements were normalized for variation in position, orientation, and scale. The image sequences were randomly divided into a training set and a cross-validation set, and discriminant function analyses were conducted on the feature point measurements. In the training set, average agreement with manual FACS coding was 92% or higher for action units in the brow, eye, and mouth regions. In the cross-validation set, average agreement was 91%, 88%, and 81% for action units in the brow, eye, and mouth regions, respectively. Automated face analysis by feature point tracking demonstrated high concurrent validity with manual FACS coding.

Adolescent↗
PubMed1997

Genetic tagging of humpback whales.

The ability to recognize individual animals has substantially increased our knowledge of the biology and behaviour of many taxa. However, not all species lend themselves to this approach, either because of insufficient phenotypic variation or because tag attachment is not feasible. The use of genetic markers ('tags') represents a viable alternative to traditional methods of individual recognition, as they are permanent and exist in all individuals. We tested the use of genetic markers as the primary means of identifying individuals in a study of humpback whales in the North Atlantic Ocean. Analysis of six microsatellite loci among 3,060 skin samples collected throughout this ocean allowed the unequivocal identification of individuals. Analysis of 692 'recaptures', identified by their genotype, revealed individual local and migratory movements of up to 10,000 km, limited exchange among summer feeding grounds, and mixing in winter breeding areas, and also allowed the first estimates of animal abundance based solely on genotypic data. Our study demonstrates that genetic tagging is not only feasible, but generates data (for example, on sex) that can be valuable when interpreting the results of tagging experiments.

Animals↗
PubMed1996

Monoclonal heavy chain (immunoglobulin G3) deposition disease: report of a case.

Seven cases of nonamyloid heavy chain (gamma chain) deposition disease have been previously reported. We describe one case of a 79-year-old woman presenting with proteinuria and microscopic hematuria whose renal biopsy showed nodular glomerulosclerosis with deposition of gamma3 heavy chains and complement in the glomeruli and tubular basement membranes with no associated light chain deposition. The patient did not have multiple myeloma. This case is unique in that in all previously reported cases of heavy chain deposition disease the gamma chain subtype has been either gamma1 or gamma4.

Aged↗
PubMed1994

Hierarchical structure of mitochondrial DNA gene flow among humpback whales Megaptera novaeangliae, world-wide.

The genetic structure of humpback whale populations and subpopulation divisions is described by restriction fragment length analysis of the mitochondrial (mt) DNA from samples of 230 whales collected by biopsy darting in 11 seasonal habitats representing six subpopulations, or 'stocks', world-wide. The hierarchical structure of mtDNA haplotype diversity among population subdivisions is described using the analysis of molecular variance (AMOVA) procedure, the analysis of gene identity, and the genealogical relationship of haplotypes as constructed by parsimony analysis and distance clustering. These analyses revealed: (i) significant partitioning of world-wide genetic variation among oceanic populations, among subpopulations or 'stocks' within oceanic populations and among seasonal habitats within stocks; (ii) fixed categorical segregation of haplotypes on the south-eastern Alaska and central California feeding grounds of the North Pacific; (iii) support for the division of the North Pacific population into a central stock which feeds in Alaska and winters in Hawaii, and an eastern or 'American' stock which feeds along the coast of California and winters near Mexico; (iv) evidence of genetic heterogeneity within the Gulf of Maine feeding grounds and among the sampled feeding and breeding grounds of the western North Atlantic; and (v) support for the historical division between the Group IV (Western Australia) and Group V (eastern Australia, New Zealand and Tonga) stocks in the Southern Oceans. Overall, our results demonstrate a striking degree of genetic structure both within and between oceanic populations of humpback whales, despite the nearly unlimited migratory potential of this species. We suggest that the humpback whale is a suitable demographic and genetic model for the management of less tractable species of baleen whales and for the general study of gene flow among long-lived, mobile vertebrates in the marine ecosystem.

Animals↗
PubMed1993

Abundant mitochondrial DNA variation and world-wide population structure in humpback whales.

Hunting during the last 200 years reduced many populations of mysticete whales to near extinction. To evaluate potential genetic bottlenecks in these exploited populations, we examined mitochondrial DNA control region sequences from 90 individual humpback whales (Megaptera novaeangliae) representing six subpopulations in three ocean basins. Comparisons of relative nucleotide and nucleotype diversity reveal an abundance of genetic variation in all but one of the oceanic subpopulations. Phylogenetic reconstruction of nucleotypes and analysis of maternal gene flow show that current genetic variation is not due to postexploitation migration between oceans but is a relic of past population variability. Calibration of the rate of control region evolution across three families of whales suggests that existing humpback whale lineages are of ancient origin. Preservation of preexploitation variation in humpback whales may be attributed to their long life-span and overlapping generations and to an effective, though perhaps not timely, international prohibition against hunting.

Animals↗
PubMed1993

[The importance of the host nutritional and immune status on the prognosis of urinary tract infection in the elderly].

This study was performed to evaluate the role of the nutritional and immune status on the prognosis of urinary tract infections (UTI) in the elderly. 192 patients among the 790 inpatients were diagnosed as UTI. Age-related increase in the prevalence of UTI was accompanied with poor prognosis in the patients with hypoalbuminemia (< 2.6 g/dl) and lymphocytopenia (< 700/mm3). To study the immunologic basis for susceptibility to UTI in the aged further, we compared the T-cell functions between outpatients without serious disease and inpatients with chronic UTI. The absolute numbers of lymphocyte, OKT3 (pan T-cell marker), OKT4 (Helper/Inducer marker) and Interleukin (IL)-2 as well as serum albumin concentration were decreased in the patients with UTI. A prospective study was done to confirm that these nutritional and immunological changes become risk factors in the prognosis of UTI with long-term and low-dose chemotherapy. In the patients continued with bacteriuria (Non-responders, n = 6), serum albumin concentration and IL-2 production were significantly lower than the patients who became free from bacteriuria (Responders, n = 7). These results suggest that poor nutrition-related immune dysfunction contributes to the vulnerability of elderly patients to UTI and becomes risks for he prognosis of UTI.

Adult↗
PubMed1990

Energy absorption from ocean waves: a free ride for cetaceans.

Flukes of cetaceans are capable of absorbing energy from ocean waves for propulsion. The extent of this energy absorption is demonstrated by considering the flukes of an immature fin whale, Balaenoptera physalus. In a fully developed seaway corresponding to a wind speed of 20 knots (around Beaufort force 5) and at a low swimming speed, of 2.5 m s-1, this whale was able to absorb up to 25% of its required propulsive power in head seas and 33% of propulsive power in following seas. Consequences of wave-energy absorption for energetics of cetacean migrations are discussed.

Animals↗
PubMed1989

Propulsion of a fin whale (Balaenoptera physalus): why the fin whale is a fast swimmer.

Measurements of an immature fin whale (Balaenoptera physalus), which died as a result of entrapment in fishing gear near Frenchmans Cove, Newfoundland (47 degrees 9' N, 55 degrees 25' W), were made to obtain estimates of volume and surface area of the animal. Detailed measurements of the flukes, both planform and sections, were also obtained. A strip theory was developed to calculate the hydrodynamic performance of the whale's flukes as an oscillating propeller. This method is based on linear, two-dimensional, small-amplitude, unsteady hydrofoil theory with correction factors used to account for the effects of finite span and finite amplitude motion. These correction factors were developed from theoretical results of large-amplitude heaving motion and unsteady lifting-surface theory. A model that makes an estimate of the effects of viscous flow on propeller performance was superimposed on the potential-flow results. This model estimates the drag of the hydrofoil sections by assuming that the drag is similar to that of a hydrofoil section in steady flow. The performance characteristics of the flukes of the fin whale were estimated by using this method. The effects of the different correction factors, and of the frictional drag of the fluke sections, are emphasized. Frictional effects in particular were found to reduce the hydrodynamic efficiency of the flukes significantly. The results are discussed and compared with the known characteristics of fin-whale swimming.

Animals↗
PubMed1985

Risk factors influencing survival in acute renal failure treated by hemodialysis.

A retrospective analysis of 58 patients with acute renal failure treated by hemodialysis between 1980 and 1984 was carried out to study mortality and the risk factors that might adversely influence survival. Twenty-six factors, suggested by published data to be relevant to the short-term prognosis of such patients, were evaluated by univariate analysis. Survivors were found to be significantly younger, they were less frequently malnourished or jaundiced, and fewer required inotropic drugs (due to hypotension) or ventilator support after the first week of their illness. Sepsis, heart failure, central nervous system depression, and a greater number of the above complications were characteristic in the nonsurvivors. Multivariate analysis suggests that the probability of survival could be estimated by taking into account three of these factors: age, central nervous system depression, and hypotension. Further studies would be appropriate to test the predictive value of such a probability equation.

Acute Kidney Injury↗
PubMed1983

Urinary cAMP and calcium excretion in the fasting state and their response to oral calcium loading in patients with calcium urolithiasis.

Fifty-two patients with idiopathic calcareous urolithiasis (ICU) were studied with an oral calcium loading test. Twenty-one subjects were normo-calciuric with no other detectable abnormalities (NDA). Of 31 patients with hypercalciuria, 16 had elevated fasting urinary calcium excretion (UCaE) (HFC), and 15 had normal UCaE (NFC). The fasting UCaE was significantly higher and the theoretical renal threshold for phosphate (TmPO4) was significantly lower in ICU patients as compared to 19 control individuals. The mean post oral calcium loading (Post Ca) UCaE rose significantly in hypercalciuric patients compared with control subjects; however, only 18/31 (58 per cent) had values above the normal range. There was no correlation between the fasting UCaE and either the immunoreactive parathyroid hormone (iPTH) or nephrogenous cAMP (ncAMP) in ICU patients. The fasting ncAMP was normal in all subjects with ICU and 7 of 52 subjects had elevated fasting iPTH values. When ranked according to the fasting UCaE value, ICU patients formed a continuum in which the NDA and HFC groups represented the extremes. It is concluded that the responses to oral Ca loading serve no useful role in the identification of an individual ICU patient either in terms of the pathogenetic subgroup or in the differentiation from normal controls.

Administration, Oral↗
PubMed1978

Changes in the red cell, plasma and inulin spaces and in the total water contents of rat femurs in cortisone induced osteoporosis.

Measurements of the bone vascular space by use of 99mTc-labelled red cells and 131I-serum albumin, and of the 3H-inulin spaces and total water contents were carried out in female rats treated for four weeks by daily subcutaneous injections of 15 mg cortisone acetate. Significant decreases in bone vascularity, inulin space and water contents were noted as compared to controls. These changes were not associated with differences in plasma calcium values, or parathyroid gland weights. They were found to be present together with significant decreases in bone density and ash contents of the femoral shafts in the steroid-treated animals. It is suggested that the changes in the vascular and extravascular fluid spaces of bones were probably consequent upon a generally depressed level of cellular activity and bone turnover, which could be found in steroid induced osteoporosis.

Animals↗