Biomedical subjects
Publications and source records attributed to J Yu.
Reaction of the fungal sesquiterpene illudin S with excess paraformaldehyde in dilute H2SO4 gives (hydroxymethyl)acylfulvene. The primary allylic hydroxyl thus formed can undergo very facile replacement by a variety of nucleophiles. (Hydroxymethyl)acylfulvene (MGI.114) was more toxic than a precursor, acylfulvene, but less toxic than the parent compound illudin S to HL 60 cells.
The capacity of recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF), glucocorticoids or all-trans-retinoic acid to modulate production of activin A by human monocytes was studied. It was shown that GM-CSF stimulated monocytes to accumulate activin A RNA after as few as 4 hr of incubation, reaching a peak of stimulation at approximately 16 hr of incubation. The activin A transcripts accumulated in the monocytes after stimulation with only 5 U/ml of GM-CSF and reached a maximum plateau level of expression between 25 and 50 U/ml of GM-CSF. Biologically active activin A molecules were detected in the conditioned media by a bioassay, performed both in the absence and presence of a neutralizing antiserum for activin A. Accumulation of bioactive activin A in conditioned medium of monocyte cultures was detected after 24 hr of incubation with GM-CSF and high levels of activin A were maintained for 72 hr. The production of the dimeric beta A beta A in these monocytes was further confirmed by sandwich enzyme-linked immunosorbent assay (ELISA) specific for activin A. In contrast to the stimulatory effect of GM-CSF, hydrocortisone, dexamethasone or all-trans-retinoic acid at 1 x 10(-7) to 1 x 10(-5) M inhibited the constitutive expression of activin A and greatly suppressed the GM-CSF-stimulated production. Thus, the expression of activin A is modulated in monocytes by different agents. These observations may imply new roles for activin A at sites of inflammation where monocytes accumulate.
Reported here are the results of a retrospective study of the speech outcome for 63 cleft subjects who had Furlow repairs compared with 20 subjects who had other procedures. The two groups of children were similar in cleft type, sex, and race. The same two surgeons repaired the palates in both groups, and the same two speech pathologists with high reliability examined the children at least 5 years postoperatively using the Pittsburgh Weighted Values for Speech Symptoms Associated with VPI (velopharyngeal incompetence). Subjects who had had Furlow repairs were superior on measures of hypernasality, articulation, and total speech scores; and fewer pharyngeal flaps were required by Furlow subjects. These findings suggest the need for randomized, double-blind investigations comparing outcome of the Furlow procedure with the intravelar veloplasty, the V-Y pushback, and other specified procedures.
The 65-kD hsp from Mycobacterium tuberculosis has been reported to induce an autopathogenic subset of T cells in at least two animal models of autoimmune disease. Reports of increased expression of human hsp60 in the inflamed synovial tissue of rheumatoid arthritis (RA) patients, increased proliferation of RA synovial fluid T cells to mycobacterial hsp65, and increased levels of anti-mycobacterial hsp65 antibody in synovial fluid, have suggested that the highly homologous human (hu) hsp60 may be recognized as an autoantigen iin RA patients. In the present study, we have examined by ELISA the serum IgG antibody levels to mycobacterial hsp65 and hu hsp60, as well as to the Escherichia coli hsp60, groEL, in patients with RA, systemic lupus erythematosus (SLE), Reiter's syndrome, active tuberculosis, and normal controls. In all these groups, the levels of anti-groEL and anti-hu hsp60 were significantly higher than the anti-mycobacterial hsp65. Anti-hu hsp60 was positively correlated with anti-groEL, but not with anti-mycobacterial hsp65. Anti-hu hsp60 was competitively inhibited by either soluble groEL or hu hsp60, but little or none by mycobacterial hsp65. Reiter's sera were found to have somewhat higher levels of anti-groEL and anti-hu hsp60 than did normal controls. We conclude that IgG anti-hu hsp60 autoantibodies arise primarily as a consequence of the humoral immune response to E. coli groEL through the recognition of cross-reactive epitopes.
In this investigation the complex multi-bundle structure of the cruciate ligaments and their interaction with the tibiofemoral joint was modeled analytically by representing the different regions of the cruciates with ligament elements. A sensitivity analysis was then performed to describe the effect that variations of the model input parameters had on the model variables (outputs). The effect that the cruciate ligament bundles had in controlling joint kinematics was dependent on knee flexion angle, and the load applied to the tibiofemoral joint. For passive range of knee motion with the thigh in the horizontal plane (a common rehabilitation activity), all cruciate ligament bundles were strained with the joint positioned between 0 and 10 deg of knee flexion, between 10 and 50 deg only the anterior bundle of the posterior cruciate ligament A-PCL was strained, and from 50 to 90 deg both the anteromedial portion of the anterior cruciate ligament A-ACL and the A-PCL were strained. This finding indicates that a strain distribution about a transverse cross section of the cruciates exists, and demonstrates the importance of differentiating between the strained and unstrained (unloaded) states of these ligaments. The strain value of a cruciate ligament bundle was an indication of how the bundle controls joint kinematics, while the unstrained values describe how much the ligament bundle must deform before it becomes strained and a restraint to tibiofemoral joint motion. In response to anterior and posterior directed loads, applied parallel to the tibial plateau, the respective, ACL and PCL load values were larger in magnitude. The sensitivity of the model outputs to the input parameters was highly dependent on knee flexion angle. The geometrical input parameters of the model (including the ligament insertion site locations and articular surface geometry) had the most pronounced effect on the model output quantities, while the stiffness and initial strain conditions of the ligament bundles had less of an effect on the model outputs. When loaded, the strain values of the ligament bundles were sensitive to the ligament insertion site position. The greatest sensitivity of the model outputs was the femoral insertion of the ACL; supporting clinical impressions and previous experimental findings. Changes in the anterior-posterior dimension of the femoral articular surface did not produce a substantial effect on the model outputs, while changes in the proximal-distal dimension created a large effect; similar results were found for the tibial surface dimensions. These findings indicate that rigid body contact between the articular surfaces may not be a realistic assumption particularly with application to the prediction of tibiofemoral compressive loading and the force/strain values of the cruciate ligament elements. This also has important implications for the design and clinical application of total knee replacements (that function as rigid bodies), particularly those that spare the PCL.
We simultaneously measured intracellular pH (pHi) and isometric tension in canine basilar arteries. pHi was calculated from the ratio of fluorescence intensities at 540 nm of exciting wavelengths of 500 and 440 nm in the presence of 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF). pHi was 7.33 +/- 0.02 in Krebs-Henseleit solution (pH of 7.4 at 37 degrees C). Application of the anion exchange blocker 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) decreased the resting pHi by 0.25 pH units. Increasing extracellular pH (pHo) [by decreasing CO2 tension (PCO2)] from 7.4 to 7.8 increased pHi by 0.38 pH units and increased tension by 2.28 +/- 0.21 mN. Decreasing pHo from 7.8 to 7.4 (by increasing PCO2) restored the pHi and muscle tension to their baseline levels. SITS inhibited the increase in pHi and isometric tension in response to the increase in pHo in an endothelium-independent fashion. The Na+/H+ exchange blockers, amiloride or 5-(N-methyl-N-guanidinocarbonylmethyl)-amiloride, did not affect the pHo or tension changes. The results suggest that in the range of pH tested, anion exchange is more important than Na+/H+ exchange in the regulation of pHi and mechanical tone in the basilar artery.
Activation of pulmonary rapidly adapting receptors (RARs) is believed to constrict airways by a vagally mediated reflex. We tested this hypothesis in dogs anesthetized with sufentanil citrate. We ventilated both lungs separately at a positive end-expiratory pressure of 4 cmH2O. We stimulated RARs in one lung under three different conditions: 1) deflation of the lung; 2) decrease in lung compliance; and 3) aerosolization of methacholine. We monitored the airway pressure in the nonstimulated lung as an index for airway muscle tone and could not detect increases in the pressure swing under these conditions. On the other hand, electrical stimulation of the distal end of cervical vagus nerve increased the pressure swing bilaterally (ipsilateral dominant), suggesting that reflex response could be detected in our preparation. Moreover, deflation (or inflation) of either lung increased (or suppressed) diaphragmatic activity. The results indicate intact vagal afferents and central response in our preparation. We conclude that activation of RARs located below the carina does not induce bronchoconstriction by a centrally mediated reflex. If any effect is present, it appears to be small.
The hypothalamic-pituitary-adrenal axis is an essential physiological system in many species. CRF, the major neuropeptide regulating ACTH secretion, is highly conserved in its primary sequence. Evolutionary conservation of the CRF sequence suggests that the CRF receptor (CRF-R) complementary DNA and examined its properties. The avian CRF-R complementary DNA encodes a 420-amino acid protein that is 87-88% identical to those of human, rat, and mouse. Most sequence divergence occurs in the putative signal peptide and the extracellular amino-terminus of the receptor. Five additional amino acids are inserted in the amino-terminus of the cCRF-R. When expressed in COS-7 cells, the cCRF-R binds the CRF and urotensin I radioligands with high affinities. Urotensin I competes for binding to the chicken CRF-R, expressed in COS-7 cells, with an apparent affinity 20 times higher than that of CRF. Both urotensin I and sauvagine were more effective in stimulating cAMP accumulation in COS-7 cells transfected with the cCRF-R than CRF. The effects of CRF and urotensin I on inositol phosphate accumulation were also tested. Urotensin I was an effective as CRF in stimulating inositol phosphate accumulation in COS-7 cells transfected with the cCRF-R. These data suggest that the sequence of the CRF-R is highly conserved from avian to mammalian species and that, despite its high sequence homology to the type A mammalian CRF-R, the ligand binding properties of cCRF-R are similar to those of the type B CRF-R i.e. a higher affinity for urotensin I than for CRF.
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OBJECTIVE: In several systems, exogenous ascorbate (reduced vitamin C) has been shown to protect against microvascular injury induced by reactive oxygen species. Since skeletal muscle is relatively resistant to oxidative injury, it is possible that under physiological conditions endogenous ascorbate in the muscle microvasculature affords such protection. To examine the ability of microvascular endothelium to accumulate ascorbate, we aimed (1) to develop an in vitro model of microvascular endothelial cells derived from rat hindlimb skeletal muscles and (2) to investigate the uptake and steady-state concentration of ascorbate in these cells. METHODS: Microvascular cells were enzymatically dissociated, isolated on a density gradient, and grown in serum-supplemented medium. After passaging, they were tested for formation of tube-like structures, coagulation factor VIII antigen expression, Griffonia simplicifolia lectin I-isolectin B4 binding, and acetylated low-density lipoprotein (LDL) uptake. Concentrations of reduced ascorbate were measured by high-performance liquid chromatography (HPLC) with electrochemical detection. Transport activity was assessed on the basis of the initial rate [14C]ascorbate uptake. RESULTS: The cultured cells tested positively for factor VIII antigen expression, lectin binding, LDL uptake, and tube formation. Although these cells did not synthesize ascorbate de novo, they accumulated reduced vitamin C when it was added to the culture medium. The initial rate of [14C]ascorbate uptake was 0.9 mumol/g cell protein 10 min when cells were incubated with 10 microM of the radiolabeled vitamin. This uptake was Na+-dependent and was blocked by the organic anion transport inhibitor sulfinpyrazone, but was not acutely affected by glucose. Following incubation with a physiological concentration of vitamin C (100 microM L-ascorbate), cells accumulated a high concentration of ascorbate within 6 h (approximately 16 mM at steady-state). Steady-state cellular ascorbate concentration was also dependent on extracellular Na+ and sensitive to sulfinpyrazone. CONCLUSIONS: Microvascular cells derived from rat hindlimb muscles demonstrated endothelial characteristics. These cells accumulated reduced vitamin C by means of Na+-dependent ascorbate transporters, which are distinct from hexose carriers. The high endothelial ascorbate concentration at steady-state is consistent with the role of ascorbate as a major antioxidant in the skeletal muscle microvasculature.
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Traditional Chinese herbal medicine was used in combination with peritoneal dialysis (PD) in order to improve the renal function and reduce the frequency of PD. The results indicated that, after 3 months of PD+TCM, the serum BUN, creatinine and mean arterial pressure of therapeutic group lowered and the hemoglobin elevated as compared with those after 1 month of PD (P < 0.01), the difference of above-mentioned criteria between PD+TCM group and less frequent PD (LEPD) group was significant too, while there was no obvious difference in comparison of the PD+TCM group with regular PD group (P > 0.05). The effective rate and the edema cure rate of TCM+PD group were superior to the LFPD group, but had no evident difference as compared with the regular PD group. The results revealed that PD combined with TCM treatment might reduce the frequency of PD for the uremia patient deserved long-term PD therapy.
By using the baculovirus expression system, we report decreases in allosteric coupling at individual gamma-aminobutyric acid (GABA)(A) receptor subtypes (alpha-1, beta-2 and gamma-2, alpha-2, beta-3 and gamma-2 and alpha-5, beta-3 and gamma-2) after chronic benzodiazepine exposure that replicate coupling changes measured in rat cortical membranes after in vivo benzodiazepine exposure. The appearance of uncoupling was time-dependent and the magnitude of uncoupling at expressed GABA(A) receptor subtypes after chronic exposure was dependent upon the efficacy of the ligand in a subtype-specific manner. In addition, the expression of uncoupling was not accompanied by changes in benzodiazepine receptor number or affinity at any expressed GABA(A) subtype examined. The specificity of the coupling change was further shown by the ability of a brief exposure to the benzodiazepine receptor antagonist, Ro15-1788, to reverse the uncoupling induced by chronic benzodiazepine exposure. These findings suggest that alterations at the GABA(A) receptor complex after chronic benzodiazepine exposure are mediated directly by agonist effects at the GABA(A) receptor complex and are not the product of the changes in the surrounding neuronal environment. Furthermore, the present study shows that drug efficacy, and not simply affinity, plays a critical role in determining the degree of uncoupling, and perhaps, in the development of tolerance and dependence.
Graft-versus-host disease (GVHD) is a serious complication following allogeneic bone marrow transplantation (BMT). Initial immunologic events that are thought to lead to clinical GVHD include allogeneic antigen presentation, CD4+ T cell proliferation and eventually generation of specific cytotoxic lymphocytes. Interleukin-10 (IL-10) has been shown to inhibit the function of antigen presenting cells (APC) and to reduce lymphocyte proliferation. In this study we investigated the possible role of recombinant murine IL-10 (rmIL-10) as prophylactic treatment of GVHD in a murine BMT model involving B10.BR donor mice (H-2k) and AKR recipients (H-2k). In particular, we wished to determine whether early post-BMT administration of IL-10 would suppress GVHD by interfering with macrophage function and inflammatory cytokine production during the proposed "afferent' phase of GVHD. In MLR assays, rmIL-10 significantly inhibited the proliferation of donor spleen cells when stimulated by irradiated recipient spleen cells in a dose-dependent manner. In murine BMT, rmIL-10 was administered exogenously by intraperitoneal injection of 100 U daily in two different dosage schedules, on days-1, 0, 1, 2, 3, 6 to target the early post-BMT phase, and days-1, 0, 3, 5, 7, 10 after BMT, to administer the same total dose throughout the engraftment period. IL-10 injected mice had lower plasma IL-1 alpha levels on day 3 (12 pg/ml vs 64 pg/ml in controls, P < 0.05), suggesting that both macrophage function and inflammatory cytokine production were inhibited. In contrast to the MLR data, no significant improvement in morbidity and mortality from GVHD was observed. Therefore, IL-10 does not appear to be useful in GVHD prophylaxis.
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Dynorphin A (1-17) [Dyn A (1-17)] is an endogenous opioid peptide. In vitro biotransformation of Dyn A (1-17) in human and rhesus monkey blood was studied by matrix-assisted laser desorption/ionization mass spectrometry. Biotransformation was observed to produce various opioid and nonopioid dynorphin A peptides. In this study, in vitro Dyn A (1-17) biotransformation at physiological temperature (37 degrees C) was found to be very similar in human and rhesus monkey blood, although Dyn A (1-17) processing occurred at a faster rate in vitro in monkey blood than in human blood. One dominant pathway in this biotransformation was the slow removal of tyrosine at position one from Dyn A (1-17) to yield the dominant product, Dyn A (2-17). Further slow biotransformation of Dyn A (2-17) also occurred. Another major pathway of Dyn A (1-17) biotransformation is cleavage of the peptide linkage between Arg(6) and Arg(7) to produce the opioid peptide, Dyn A (1-6), and the nonopioid peptide, Dyn A (7-17). These two peptides had a short lifetime in blood, undergoing rapid biotransformation. Our results indicate that the rhesus monkey may be a good model for further in vivo pharmacological and neurobiological studies.
Hematopoiesis is regulated by complex interactions between hematopoietic cells and stromal cells within the bone marrow microenvironment. The stromal cells of this microenvironment secrete hematopoietic factors, produce extracellular matrix and mediate direct cell-to-cell contact; each of these events provides a basis for regulatory control of hematopoiesis. With advances in cell surface phenotyping and cell separation technology, it has been shown that the CD34+CD38-CD45RAlowCD71low population contains hematopoietic stem cells. Most hematopoietic stem cells are in a quiescent, noncycling state (G0). In response to external signals, however, they can rapidly enter a functional state (G1) in preparation for DNA synthesis (S-phase). There have been high expectations, recently, that stimulatory hematopoietic factors will have an important impact on chemotherapy by reducing drug-induced neutropenia and, thereby, allowing dose-intensification of treatment. Similar clinical benefits, however, could also be realized by protecting hematopoietic cells from the cytotoxicity of cycle-specific chemotherapeutic agents by blocking the entrance of the hematopoietic stem cells into the cell cycle. Recent studies have suggested that the addition of a negative regulator can better maintain hematopoiesis in vitro and that cells capable of long-term engraftment are primarily comprised of a noncycling population. On the other hand, exposure to cycling-promoting cytokines ex vivo may produce an "engraftment defect". An hu-SCID murine model with a high degree of human cell engraftment will be useful for future studies of the in vivo effects of various agents, infections or gene therapy on human hematopoiesis.
Studies of recombination between the markers D6S291 and D6S109 in individuals by sperm typing provide direct evidence for significant variation in recombination among humans. A statistically significant difference in the recombination fraction (range 5.1%-11.2%) was detected among five donors. This variation could reflect polymorphisms in genes affecting recombination or in chromosome structure. Ignoring this variability in studies designed to examine the relationship between physical and genetic distances could lead to incorrect inferences. Individual variation in recombination makes it difficult to predict the recombination fraction for an interval in any particular individual. This could be important in certain genetic counseling situations.