The technical aspects of combined intestinal and heart transplantation in rats.
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Anastomosis, Surgical↗
Biomedical subjects
Y Lu
Publications and source records attributed to Y Lu.
Intestinal allografts delay rejection and prolong survival of combined donor-specific and third party solid organ transplants.
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Anastomosis, Surgical↗
Mechanoreceptors and reflex arc in the feline shoulder.
A reflex arc from the glenohumeral capsule to the biceps, infraspinatus, supraspinatus, and subscapular muscles was shown in a feline preparation. Branches of the suprascapular and subscapular nerves terminating in the capsule were identified and then stimulated with a 100 microseconds supramaximal pulse at 10 pulses per second. Stimulation of the suprascapular articular nerve elicited electromyographic discharge in the biceps and infraspinatus muscles, whereas stimulation of the subscapular articular nerve elicited electromyographic discharge in the biceps, subscapularis, infraspinatus, and supraspinatus muscles. When the articular nerves were transected between their emergence from the main nerve trunk and the stimulation electrodes, the electromyographic discharge was abolished confirming the afferent nature of the nerves. The mean time delay ( +/- SD) from application of the stimulus to the peak of the recorded electromyographic activity was 3.2 +/- 0.27 msec. Anatomic dissection and staining of the capsule segments where the articular nerves terminated revealed mechanoreceptors consisting primarily of free nerve endings and Golgi tendon organs, Ruffini's endings, and pacinian corpuscles. The existence of a ligamento-muscular reflex arc in the glenohumeral joint extends the concept of passive and active restraints of a joint by virtue of the synergy between ligaments and muscles. That such a reflex exists may advocate modification of surgical repairs of the capsule, leading to preservation of as many neurologic structures as possible; it may also form the foundation for new postsurgical therapeutic modalities.
Animals↗
Poly(ethylene glycol)-conjugated anti-EGF receptor antibody C225 with radiometal chelator attached to the termini of polymer chains.
Several biological barriers, including significant liver uptake, limit the clinical application of radiolabeled antibodies in radioimmunoscintigraphy. Here, a general approach is described for radiolabeling of monoclonal antibodies conjugated with poly(ethylene glycol) (PEG). This strategy is demonstrated with C225, a monoclonal antibody directed against epidermal growth factor (EGF) receptor. We synthesized a heterofunctional PEG with one end attached to a radiometal chelator, diethylenetriaminepentaacetic acid (DTPA), and the other end to a protected thiol group, S-acetylthioacetate. After a deprotection step, the resulting DTPA-PEG-SH was conjugated to maleimide-activated C225 to yield DTPA-PEG-C225 conjugate. Characterization of DTPA-PEG-C225 with immunoprecipitation and Western blot analysis revealed that the conjugate was biologically active in binding to the EGF receptor in A431 cells. Competitive EGF receptor binding assay in MDA-MB-468 cells showed that DTPA-PEG-C225, with up to 60% of the amino groups in C225 substituted, retained 66% of C225's binding affinity. Moreover, DTPA-PEG-C225 with increasing degrees of NH(2) substitution from 20% to 70% retained the activity of C225 to induce apoptosis in DiFi cells. More importantly, DTPA-PEG-C225 demonstrated less nonspecific interaction than DTPA-C225. Pharmacokinetic analysis using (111)In-labeled compounds revealed narrower steady-state distribution of (111)In-DTPA-PEG-C225 than (111)In-DTPA-C225, probably due to reduced nonspecific binding of PEG-modified antibody to tissues. The terminal half-life (t(1/2,)(gamma)) of (111)In-DTPA-PEG-C225, 21.1 h, was shorter than that of (111)In-DTPA-C225, 52.9 h. These data suggest that (111)In-DTPA-PEG-C225 may provide better imaging characteristics than (111)In-DTPA-C225, and that using PEG as a linker between the monoclonal antibody and DTPA may be a promising strategy in optimizing the imaging characteristics of immunoscintigraphic agents.
Antibodies, Monoclonal↗
Delivery of adenoviral vectors to the prostate for gene therapy.
Prostate cancer has become the most frequently occurring cancer and the second leading cause of cancer deaths in men. One novel approach to combat prostate cancer is gene therapy. A replication-deficient recombinant adenoviral vector (AdRSVlacZ) expressing bacterial beta-galactosidase (beta-gal) (lacZ) under the control of the Rous sarcoma virus promoter was used to determine which delivery route was best for the transduction of adenoviral vectors to the prostate. Using a canine model, adenoviral vectors were administered by intravenous, intra-arterial, and intraprostatic (i.p.) injections. After injections, the expression of the lacZ gene was measured in canine prostates as well as in various other organs to determine the distribution of the disseminated adenoviral vector by (a) the percentage of cells expressing lacZ in situ (5-bromo-4-chloro-3-indolyl beta-D-galactoside staining), (b) beta-gal enzymatic activity (colorimetric beta-gal assay), and (c) polymerase chain reaction of genomic DNA using primers specific for the adenoviral genome. An i.p. injection of the adenoviral vector resulted in a greater transduction rate and expression level of lacZ in the prostate than either intravenous or intra-arterial (inferior vesical/prostatic artery) injections. Thus, an i.p. (or intratumoral) injection seems to be the best route to treat local regional prostate cancer by viral-based gene therapy.
Adenoviridae↗
In vivo expression of prostate-specific adenoviral vectors in a canine model.
The activity and expression of transgene beta-galactosidase (lacZ) by replication-deficient adenoviral vectors (Ad-lacZ) containing prostate-specific promoters were compared using an in vivo canine model. The prostate tissue-specific promoters were prostate-specific antigen, probasin, and mouse mammary tumor virus long-terminal repeat, which were fused separately to an Escherichia coli lacZ gene. Dogs underwent laparotomy, and adenoviral vectors were delivered by direct intraprostatic injection. At 72 hours postinjection, the prostate and various other organs were harvested to evaluate the degree of prostate expression and dissemination of adenoviral vectors. Expression of lacZ in tissues was determined by 5-bromo-4-chloro-3-indolyl beta-D-galactoside staining, beta-galactosidase assay, and E. coli lacZ reverse transcriptase-polymerase chain reaction (PCR). The presence of adenoviral DNA sequences in canine tissues was determined by PCR using primers specific for the type 5 adenoviral genome. All three of the prostate-specific adenoviruses tested effectively expressed the lacZ gene in the canine prostate, but expression levels were lower than that of the control viral vector AdRSVlacZ following intraprostatic injection. By PCR, adenoviral vector DNA was detected in other organs and tissues, including the bladder and vas deferens. However, reverse transcriptase-PCR analysis revealed that prostate-specific Ad-lacZ vectors only transcribed lacZ mRNA in the prostate and not in nonprostatic tissues. Thus, these novel prostate-specific adenoviral vectors each have equal in vivo expression exclusively in the prostate and may potentially be used for prostate cancer gene therapy.
Adenoviridae↗
The effect of monopolar radiofrequency energy on partial-thickness defects of articular cartilage.
PURPOSE: To evaluate the effect of monopolar radiofrequency (RF) energy on partial-thickness defects of articular cartilage, comparing the outcome of partial-thickness defects treated with monopolar RF energy with that of treatment by conversion of partial-thickness defects to full-thickness defects by curettage and microfracture. TYPE OF STUDY: Randomized trial using adult female sheep. MATERIALS AND METHODS: Thirty-six sheep were used in this study. Both stifles in each animal were randomly assigned to 1 of the following 3 procedures: (1) partial-thickness defect without any treatment to serve as a sham-operated control, (2) partial-thickness defect with RF energy treatment, and (3) partial-thickness defect treated by conversion of the defect to a full-thickness defect by curettage and microfracture. Nine sheep were euthanized at 0, 2, 12, and 24 weeks after surgery (n = 6 per group). After euthanasia, cartilage samples were harvested from the defect sites, and chondrocyte viability was analyzed by confocal laser microscopy using a triple-labeling technique. Cartilage samples also were decalcified and stained with hematoxylin and eosin and safranin-O for histologic analysis. Surface properties of cartilage samples were analyzed using scanning electron microscopy. RESULTS: The analysis of chondrocyte viability showed that RF treatment caused death of almost all chondrocytes in the defect. Histologic analysis showed that RF treatment caused detrimental effects to chondrocytes and proteoglycan concentration that progressed over time, and that full-thickness defects were repaired by fibrocartilage by 24 weeks after surgery. Scanning electron microscopy analysis indicated that RF-treated groups were significantly smoother and less irregular than control groups at 2, 12, and 24 weeks after surgery. CONCLUSIONS: This study showed that monopolar RF energy caused long-term damage to cartilage in this sheep model and did not appear to have the beneficial effects reported in a previous study that evaluated application of this technique using a bipolar RF probe.
Animals↗
Canine pubic symphysiodesis: investigation of electrocautery dose response by histologic examination and temperature measurement.
OBJECTIVES: To determine thermal necrosis zone and the maximal temperature achieved with various electrocautery doses applied to the pubic symphysis of immature dogs, and to establish the minimal electrocautery dose needed to affect thermal necrosis of the germinal chondrocytes of the immature canine pubis. STUDY DESIGN: A randomized, controlled, prospective study. ANIMALS: Twelve puppies, 15 to 17 weeks of age. METHODS: Each treated puppy was randomly selected to receive 3 of 33 possible doses of electrical current applied at uniform intervals along the pelvic symphysis. Three treatment sites were sham-operated controls. All treatment zones were biopsied 7 days after application of electrocautery. Confocal laser microscopy with calcein green and ethidium homodimer red stains were used to determine cell type and viability within treatment and control zones. The physeal diameter and thermal necrosis zone were measured. Thermal necrosis zone and dose, and temperature and dose were compared using regression analysis. Prediction equation analysis was used to establish dose recommendations. RESULTS: Doses of 40 W produced a highly significant linear relationship (R(2) =.88, P <.01) with thermal necrosis zone, and a significant linear relationship (R(2) =.76, P <.02) with maximal temperature. CONCLUSIONS: The thermal necrosis zone within the pelvic symphysis and maximal temperature achieved can be reliably predicted using electrocautery doses of 40 W. For application of electrocautery to induce pubic symphysiodesis, doses should be chosen based on measured or estimated physeal size. Using prediction equation analysis, the surgeon can plan mean thermal necrosis zone with acceptable variance. CLINICAL RELEVANCE: Unipolar needle electrocautery can be used to reliably achieve symphyseal necrosis. Prediction equation analysis can be used to determine 40-W doses.
Animals↗
The mechanism of synovial fluid retention in pressurized joint cavities.
OBJECTIVE: Hyaluronan (HA) in synovial fluid is vital to fluid retention in joint cavities. This study aims to evaluate a HA concentration polarization hypothesis and to examine, quantitatively, the agreement between theoretical predictions and experimental results. METHODS: A non-steady-state model was developed for HA ultrafiltration and concentration polarization on the synovial surface. The Kedem-Katchalsky equation was used to calculate the trans-synovial filtration rate Q as the HA concentration polarization layer built up. Model parameters were based on data from experiments. Effects of parameters on fluid filtration were investigated. RESULTS: The HA osmotic pressure at the synovial surface was found to approach the intra-articular pressure, P, during fluid infusion. The model simulated the experimentally observed decay in Q with the time at constant P, and predicted nonlinear P-Q relations in good agreement with experimental results over a range of bulk HA concentrations, from pathological (0.2 g L(- 1)) to physiological (4.0 g L(-1)). It gave quantitative insights into the development of the osmotic pressure and the significance of the HA reflection coefficient. CONCLUSIONS: The osmotic pressure of a HA concentration polarization layer on the synovial surface leads to outflow buffering. This provides the mechanism by which the vital lubricating synovial fluid is retained in a joint cavity under pressure.
Animals↗
Characterization of the Pseudomonas syringae pv. syringae 61 hrpJ and hrpI genes: homology of HrpI to a superfamily of proteins associated with protein translocation.
The Pseudomonas syringae pv. syringae 61 hrpJ and hrpI genes were sequenced and found to encode predicted proteins of 37,710 Da and 76,490 Da, respectively. The products of these genes were confirmed by T7 polymerase-dependent expression and sodium dodecyl sulfate-polyacrylamide gel analysis. HrpI belongs to a superfamily of proteins represented by Yersinia pestis LcrD.
Bacterial Proteins↗
Breast cancer resistance protein-mediated topotecan resistance in ovarian cancer cells.
Overexpression of breast cancer resistance protein (BCRP) and mitoxantrone (MX) resistance protein can confer resistance to a variety of cytostatic drugs, such as MX, topotecan (TPT), doxorubicin, and daunorubicin. This study investigates the role of BCRP in resistance of ovarian cancer to TPT treatment. We have developed TPT-resistant human ovarian cancer cell line. Intracellular concentration of fluorescent dye rhodamine 123 (Rh123) was measured by flow cytometry. The expression of several membrane transporter proteins including P-glycoprotein (P-gp), multidrug resistance protein 1 (MRP1), and BCRP were determined by reverse transcription-polymerase chain reaction and Western blotting. The Rh123 concentration in parental cells was approximately three times of those in TPT-resistant cells. In contrast to undetectable level of P-gp messenger RNA (mRNA) and minimal level of MRP1 expression in TPT-resistant cells, overexpression of both the BCRP mRNA and the protein was detected in these cells. Introduction of antisense-phosphorothioate oligonucleotide derived from BCRP mRNA into TPT-resistant cells resulted in a significant increase in the concentration of intracellular Rh123. These results suggested a novel mechanism in which a reduced intracellular drug concentration may be mediated by BCRP gene products in human ovarian cancer cells.
ATP Binding Cassette Transporter, Subfamily G, Mem↗
Ras modulates commitment and maturation of 10T1/2 fibroblasts to adipocytes.
The positive association of the ras oncogene with human cancer and the recognition that malignancy may, in part, represent the imbalance between cell proliferation and differentiation have generated intense interest in the potential role of ras in cell differentiation. We investigated this possibility utilizing as a model system the differentiation of the mesenchymal cell line C3H 10T1/2 (10T1/2) to adipocytes, and a series of transfectants of 10T1/2 cells in which the level of the ras gene product (p21ras; Ras) can be effectively up- or down-modulated. In agreement with previous reports, we found that 10T1/2 cultures, propagated in the resting state for several weeks, spontaneously convert to fat cells at a very low frequency. Downmodulation of endogenous p21ras levels, as a consequence of expression of antisense ras, markedly increased the rapidity and frequency of adipose conversion (6- to 10-fold), which was equivalent in magnitude to that effected by the potent differentiating agent 5-azacytidine. Conversely, overexpression of ras completely inhibited cell differentiation. In addition, adipocytes derived from antisense-ras expressing lines were characterized by a decrease in hormone responsiveness, as well as an apparent deficiency in attaining the terminally differentiated state. These findings suggest that Ras may be a negative regulator of the decision-making step of fibroblast differentiation to adipocytes. In addition, Ras may play an essential positive role in the transduction of hormonal signals necessary for full adipocyte maturation during later progression along the differentiation pathway.
Adipose Tissue↗
Using Markov processes to describe the prognosis of HIV-1 infection.
In 1989, Turner and colleagues proposed a new method for automated classification and prediction of outcomes for hospitalized patients with AIDS, based on severity of illness. The authors have confirmed this system, which includes three main stages and 20 substages, in a cohort of HIV-1-infected symptomatic patients admitted to the Miami Veteran's Affairs Medical Center (VAMC) since 1988. They propose a new model of Markov illness-and-death processes and use it to describe the disease progression of the patient cohort. The new Markov model also measures transitions between stages, including risk factors associated with the speed of transitions. Significant differences in survival experiences were found from the different disease stages. The estimated mean (median) survival times were: from stage 1, 21.0 (17.8) months; from stage 2, 10.5 (8.4) months; and from stage 3, 6.7 (4.7) months. In addition, age at HIV-1 diagnosis and homosexual behavior were significant prognostic factors for disease progression and survival. The results indicate that the combination of a severity-of-illness clinical staging system with Markov illness-and-death process modeling is particularly useful for the evaluation of prognostic factors influencing the course of HIV-1 disease progression.
Acquired Immunodeficiency Syndrome↗
The effect of monopolar radiofrequency treatment pattern on joint capsular healing. In vitro and in vivo studies using an ovine model.
The purpose of this study was to compare joint capsular healing after two delivery patterns of monopolar radiofrequency energy: 1) uniform treatment of the joint capsule (paintbrush pattern) and 2) multiple single linear passes (grid pattern). First, an in vitro study was performed to compare the percent shrinkage of these two treatment patterns using the femoropatellar joints (stifles) of six sheep. Monopolar radiofrequency energy (settings, 70 degrees C/15W) was applied to the lateral joint capsule; the treated area was approximately 10 x 10 mm. There was no significant difference in shrinkage between the grid (27% +/- 8.7%) and paintbrush (29% +/- 7.9%) patterns. In the in vivo study, stifles of 24 sheep were randomly assigned to the paintbrush or the grid pattern groups and treatment was performed arthroscopically. Sheep were sacrificed immediately after surgery, or at 2, 6, or 12 weeks after surgery. At 6 weeks after surgery, confocal microscopy demonstrated that treated areas had almost completely repaired in the grid group; some nonviable areas were still present in the paintbrush group. Mechanical testing at 6 weeks indicated that joint capsule in the grid group had better mechanical properties than capsule in the paintbrush group. This study revealed that radiofrequency treatment of joint capsule in a grid pattern allowed faster healing than tissue treated in a paintbrush pattern.
Animals↗
Anterior-posterior and rotational displacement of the tibia elicited by quadriceps contraction.
The anterior-posterior displacement and rotation of the tibia elicited by isolated loading of the quadriceps muscle was determined as a function of joint angle and muscle load using a computerized radiographic technique. Data collected from 12 fresh-frozen cadaveric knees demonstrated that quadriceps contraction can result in significant (less than 7 mm) anterior displacement of the tibia in the range of 0 degrees to 80 degrees of flexion, and a mild (less than 2 mm) posterior displacement in the range of 80 degrees to 120 degrees of flexion. Peak anterior displacement of 6.3 mm was observed at 30 degrees of flexion under a 12 kg load in the quadriceps, while a constant 1.5 mm posterior displacement was observed throughout flexion angles exceeding 80 degrees. It was further shown that the magnitude of the anterior displacement increased nonlinearly as the quadriceps force increased. Loading of the quadriceps also resulted in internal rotation of the tibia in the range of 0 degrees to 90 degrees of flexion, and in external rotation of the tibia in the range of 90 degrees to 120 degrees. Peak internal rotation of 7 degrees was observed at 15 degrees of flexion and a peak external rotation of 1 degrees was detected at 120 degrees of flexion. Larger quadriceps load resulted in larger rotation. We concluded that quadriceps contraction during knee extension has direct impact on anterior displacement and rotation of the tibia and therefore on anterior cruciate ligament stress, increasing it as the muscle's force is increased during knee extension.(ABSTRACT TRUNCATED AT 250 WORDS)
Anterior Cruciate Ligament↗
The synergistic action of the capsule and the shoulder muscles.
The existence of a reflex arc from the glenohumeral capsule to several muscles crossing the shoulder joint was determined in the feline model. Three branches of the axillary nerve terminating in the glenohumeral capsule were identified and electrically stimulated with supramaximal, 100-microseconds pulses using bipolar hook electrodes. Stimulation of the anterior and the inferior axillary articular nerves elicited electromyographic activity in the biceps, subscapularis, supraspinatus, and infraspinatus muscles. Stimulation of the posterior axillary articular nerve elicited electromyographic activity in the acromiodeltoid muscle. Transection of the three articular nerves just distal to their emergence from the main axillary nerve resulted in the absence of any electromyographic activity in the muscles on stimulation, confirming the afferent nature of the articular branches. The time from application of the stimulus to the appearance of a response in the muscles varied from 2.7 msec in the biceps to 3.1 msec in the supraspinatus. The existence of a reflex arc from mechanoreceptors within the glenohumeral capsule to muscles crossing the joint confirms and extends the concept of synergism between the passive (ligaments) and active (muscles) restraints of the glenohumeral joint. This provides new information in orthopaedic sciences that has direct application in modification of surgical repairs and therapeutic modalities of shoulder injuries.
Animals↗
The thermal effect of monopolar radiofrequency energy on the properties of joint capsule. An in vivo histologic study using a sheep model.
The purpose of this in vivo study was to analyze the short-term tissue response of joint capsule to monopolar radiofrequency energy and to compare the effects of five power settings at 65 degrees C on heat distribution in joint capsule. In 12 mature Hampshire sheep, the medial and lateral aspects of both stifles were treated with monopolar radiofrequency energy under arthroscopic control in a single uniform pass to the synovial surface. The radiofrequency generator power settings were 0, 10, 15, 20, 25, and 30 watts (N = 8/group). The electrode tip temperature was 65 degrees C. Histologic analysis at 7 days after surgery revealed thermal damage of capsule at all radiofrequency power settings. The lesion's cross-sectional area, depth, vascularity, and inflammation were commensurate with radiofrequency power. Tissue damage was indicated by variable inflammatory cell infiltration, fusion of collagen, pyknosis of fibroblasts, myonecrosis, and vascular thrombosis, whereas synovial hyperplasia, fibroblast proliferation, and rowing of sarcolemmal nuclei demonstrated regenerative processes. This study revealed that radiofrequency power settings and heat loss through lavage solution play a significant role in heat distribution and morphologic alterations in joint capsule after arthroscopic application of monopolar radiofrequency energy.
Animals↗
Monopolar radiofrequency energy effects on joint capsular tissue: potential treatment for joint instability. An in vivo mechanical, morphological, and biochemical study using an ovine model.
The purpose of this study was to evaluate the thermal effect of monopolar radiofrequency energy, a potential treatment means for joint instability, on the mechanical, morphologic, and biochemical properties of joint capsular tissue in an in vivo ovine model. The energy was applied arthroscopically to the synovial surface of the femoropatellar joint capsule of 24 sheep. The sheep were sacrificed at 0, 2, 6, and 12 weeks after surgery (6 per group). Monopolar radiofrequency energy initially caused a significant decrease in tissue stiffness and an increase in tissue relaxation properties, followed by gradual improvement in the tissue's mechanical properties by 6 weeks after surgery. Microscopic examination illustrated that radiofrequency energy initially caused collagen hyalinization and cell necrosis, followed by active tissue repair. Biochemical analysis revealed that treated collagen was significantly more trypsin-susceptibile than untreated collagen at 0 and 2 weeks after surgery, indicating early collagen denaturation. This study demonstrated that this treatment initially caused a significantly deleterious effect on the mechanical properties of the joint capsule, which was associated with partial denaturation of joint capsular tissue. This was followed by gradual improvement of the mechanical, morphologic, and biochemical properties of the tissue over time.
Animals↗