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Biomedical subjects

W Kong

Publications and source records attributed to W Kong.

At least 55 records · Page 3Linked to original sources
PubMed1996

[Application of laser scanning confocal microscopy in inner ear morphological studies].

Laser scanning confocal microscope (LSCM) enables one to observe both the surface structure and the inner configuration in the same specimen, by its possibility of direct, non-invasive serial optical sectioning of whole mounted specimens. The potential value of LSCM in the field of inner ear morphological study was evaluated. The configuration of upper parts of organ of Corti was observed with the LSCM combined with double-stained fluorescence immunohistochemistry technique. The actin filament of hair cells by phalloidin, and the cytokeratin of supporting cells by monoclonal pan-anticytokeratin antibody. The stereocilia, cuticular plate, and the cuticle-free area of hair cells were well demonstrated. In the same specimen, the head plate of outer pillar cell, the phalangeal apical plate and the phalangeal process of Deiter cells were clearly showed as well. LSCM provide a new tool to the morphological study of organ of Corti.

Animals↗
PubMed1995

Cancellous bone Young's modulus variation within the vertebral body of a ligamentous lumbar spine--application of bone adaptive remodeling concepts.

Bone remodeling theory based on strain energy density (SED) as the feedback control variable was used in conjunction with the finite element method to analyze the shape of the vertebral bodies within the ligamentous motion segment. The remodeling theory was once again applied to the altered two motion segments model to predict the Young's modulus distribution of the cancellous bone within the vertebral bodies. A three-dimensional finite element model of the two motion segments ligamentous lumbar spine (L3-5) was developed. Bone remodeling response (external as well as internal) of the motion segments to a uniaxial compressive load of 424.7 N was studied. The external shape of the converged model matched the normal shape of a vertebral body. The internal remodeling resulted in regional cancellous bone Young's moduli (or bone density) distributions similar to those reported in the literature; posterocentral regions of the vertebrae were predicted to have greater values of the elastic modulus than that of the outer regions. The results of the present study suggest that vertebral body assumes an adequate/optimum structure in terms of both its shape and its elastic moduli distribution within the cancellous region in response to the applied load. Extensions of the present model and its clinically relevant applications are discussed.

Adaptation, Physiological↗
PubMed1995

Presence of insulin-like growth factor I but absence of the binding proteins in the bile of rats.

Whereas insulin-like growth factor I (IGF-I) has been found in various body fluids from different species, the presence or absence of IGF and associated binding proteins (IGFBPs) in bile has not been clearly defined. Bile concentration of IGF-I was measured in this study and found to be highest in the neonate and lowest in adult rats [133 +/- 15.9, 79.4 +/- 10.5, 45.3 +/- 12.7 ng/ml (mean +/- SE) in 12-day-old, 33-day-old, and adult rats, respectively]. When bile delivery rates of IGF-I (i.e., the product of IGF-I concentration in bile and the biliary flow rate) were calculated, IGF-I delivery was highest in weanling rats (469 pg.h-1.g body wt-1). When expressed as amount of IGF-I in bile delivered per day, however, delivery rates rose from 0.2 micrograms/day in the suckling and remained constant at 1.6-1.7 micrograms/day in both weanling and adult animals. Bile samples exposed to a placental membrane IGF receptor preparation showed significant dose-dependent inhibition of binding of native IGF-I. Because no IGF binding proteins were identified by Western ligand blot or by Sephadex gel chromatography, the results suggest the presence of biologically significant quantities of bioactive IGF-I in bile. We speculate that IGF-I in bile may play an important role in the growth of the gastrointestinal tract, both in the suckling as well as later in life.

Animals↗
PubMed1995

Dendritic cells in the normal human tympanic membrane.

Dendritic cells (DCs) are antigen-presenting cells that possess an outstanding capacity to initiate primary immune responses. They reside in the tissues in an immunologically immature state. Upon antigenic challenge in vivo or short-term culture in vitro, they undergo a maturation process and turn into mature "lymphoid DCs." Langerhans cells (LCs) of the epidermis were identified as members of this DC system. They have been demonstrated in cholesteatoma matrix and in inflamed tympanic membranes, but the normal tympanic membrane was hitherto thought to be devoid of them. To clarify this question, we removed 12 normal tympanic membranes postmortem and processed them for a sheet preparation. The epidermal layers were peeled off and immunostained with the following monoclonal antibodies: HLA-DR, OKT6/CD1a, and LAG (specific for the Birbeck granules of LCs). Two tympanic membranes were also processed for routine electron microscopy. In all epidermal sheets a dense network of DCs could be demonstrated. They showed a positive immunostaining reaction with HLA-DR, but a negative one with OKT6 and LAG. Thus, they differ in their immunohistochemical properties from typical epidermal LCs. At the ultrastructural level, DCs could also be identified, but without the typical Birbeck granules. This explains the negative reaction with the LAG antibody. These findings were extended and supported by a tissue culture examination of three normal tympanic membranes. After 3 days, typical "veiled" cells (ie, mature DCs), showing positive immunostaining with HLA-DR, could be recovered from the culture medium. In an oxidative mitogenesis assay, these cells displayed strong stimulatory capacity for resting T lymphocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Movement↗
PubMed1994

Stress analysis of a canine spinal motion segment using the finite element technique.

Canine models have been frequently employed to investigate the in vivo effects of a surgical procedure. Various studies indicate that canine models can provide a successful in vivo biological model for these studies. Use of canine models for the biomechanical studies of the spine, however, have been questioned because of different loading conditions on the canine and human spines originated from posture differences between canine and human. Similarities between the stress distributions within the canine and human motion segments under physiological loads will strengthen the use of canine models for the studies of spine biomechanics. In the present study, finite element models of the canine intact and stabilized motion segments were developed to investigate these aspects. Comparison of model predicted flexion angle, axial stiffness, and facet contact force for the canine intact L6-L7 motion segment revealed good agreement with the corresponding parameters experimentally measured under the similar loading conditions. Similar stress distributions within the intact canine and human models were found from the predicted results in response to the physiological load. Stabilizing and stress-shielding effects of a pedicle screw-plate-type fixation device [variable spinal plating (VSP)] on the stabilized motion segment were also similar for the canine and human stabilized models. Furthermore, maximum stresses in the pedicle screws were found at the junction between the bone screw and the integrated nut of the inferior screw in both the canine and human stabilized models. This corresponds to the location of pedicle screw breakage reported in the literature. These findings suggest that a canine is a suitable model for the biomechanical studies of the lumbar spine.

Animals↗
PubMed1994

Investigation of vibration characteristics of the ligamentous lumbar spine using the finite element approach.

A nonlinear, three-dimensional finite element model of the ligamentous L4-S1 segment was developed to analyze the dynamic response of the spine in the absence of damping. The effects of the upper body mass were simulated by including a mass of 40 kg on the L4 vertebral body. The modal analyses of the model indicated a resonant frequency of 17.5 Hz in axial mode and 3.8 Hz in flexion-extension mode. Accordingly, the predicted responses for the cyclic load of -400 +/- 40 N applied at four different frequencies (5, 11, 16.5, and 25 Hz) were compared with the corresponding results for axial compressive static loads (-360, and -440 N). As compared to the static load cases, the predicted responses were higher for the cyclic loading. For example, the effect of cyclic load at 11 Hz was to produce significant changes (9.7-19.0 percent) in stresses, loads transmitted through the facets, intradiscal pressure (IDP), disk bulge, as compared to the static load predictions. The responses were found to be frequency dependent as well; supporting the in vivo observations of other investigators that the human spine has a resonant frequency. For example, the 11 Hz model (DYN11) compared to the DYN5 model showed an increase in majority of the predicted parameters. The parameters showed an increase with frequency until 17.5 Hz (resonant frequency of the model); thereafter a decrease at 25 Hz.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗
PubMed1994

High density cultivation of a recombinant CD-1 cell line producing prourokinase using a Biosilon microcarrier culture system.

CD-1, a genetically-engineered CHO cell line, was cultivated with a Biosilon microcarrier culture system. We successfully cultivated CD-1 cells to a very high density (over 1 x 10(7) cells/ml). Prourokinase was stably secreted at about 180 IU/10(6) cells/24 h. Experiments showed that CD-1 cells growing on Biosilon microcarriers were able to spontaneously release from the microcarriers, then reattach and proliferate on fresh microcarriers. This makes it very easy to scale up production. The microcarriers could be reused several times without affecting adhesion, proliferation and prourokinase secretion. With CM-PECC membrane radial flow chromatography and MPG chromatography, the prourokinase in conditioned medium could be purified to a specific activity of 1 x 10(5) IU/mg of protein. The purification factor was about 600 fold, and approximately 90% of the biological activity was recovered.

Animals↗
PubMed1993

A combined finite element and optimization investigation of lumbar spine mechanics with and without muscles.

A combined finite element and optimization approach to study the effects of muscles on the biomechanics of the lumbar spine was initiated. Briefly, a three-dimensional, nonlinear, finite element model of a ligamentous L3-4 motion segment was formulated (LIG model) for the predictions of stresses, etc., in the motion segment. A separate, biomechanical optimization-based force model with experimental input was developed to predict the forces in muscles and disc across the L3-4 segment in response to a person holding 90 N in his hands with spine flexed 30 degrees, and knees straight. The predicted muscle forces from the optimization model were then incorporated into the L3-4 finite element model as nodal forces to simulate the muscle action (MUS model). The predicted responses from the muscles active (MUS) finite element model were compared to the corresponding results from the ligamentous (LIG) finite element model subjected to an equivalent load. The biomechanical parameters compared were: translation and rotation of L3, disc bulge, intervertebral foramen gap, intradiscal pressure, facet loading, ligament tension, compressive disc load, and stresses in the vertebral body. The addition of muscular forces in the MUS model led to a decrease in the anteroposterior translation and flexion rotation (displacements in the sagittal plane) of the segment compared to the corresponding LIG model predictions. Thus, the muscles imparted stability to the ligamentous segment. The presence of muscles also led to a decrease in stresses in the vertebral body, the intradiscal pressure and other mechanical parameters of importance. However, the load bearing of the facets increased compared to the ligamentous model. Thus, facets play a significant role in transmitting loads in a normal intact spine. These results, for the first time, provide quantitative data on the stabilizing effects of muscles on the mechanics of a ligamentous spine. The results also provide a scientific explanation in support of the "degenerative cascade" concept proposed in the literature. The model predictions, in conjunction with the degenerative cascade concept, also support the observation that the osteoarthritis of facets may follow disc degeneration. Future research directions based on the current model are presented.

Biomechanical Phenomena↗
PubMed1993

A 9-year follow-up study of the immunogenicity and long-term efficacy of plasma-derived hepatitis B vaccine in high-risk Chinese neonates.

The long-term immunogenicity of and protection provided by a plasma-derived hepatitis B vaccine was determined in a cohort of 98 susceptible Chinese neonates immunized in 1982-1983. Within 24 hours of birth, 89 infants received the first of three 30-micrograms doses of vaccine (at 0, 1, and 6 months) and were subsequently followed up by testing for serological markers of hepatitis B virus and by determining levels of alanine aminotransferase annually for 9 years. After the primary series of vaccine doses, 74 (83%) of 89 subjects developed antibody to hepatitis B surface antigen (anti-HBs). At the 9-year follow-up, 51% of vaccinees still had levels of antibody of > or = 10 mIU/mL, considered the protective level. Seven responders to vaccine (9.4% of 74 evaluable patients) developed antibody to hepatitis B core antigen, and in six of these responders, levels of anti-HBs increased transiently. None of the vaccinees developed chronic carriage of hepatitis B surface antigen or clinical hepatitis. Immunization of high-risk neonates with a plasma-derived hepatitis B vaccine can induce long-lasting protective immunity that can prevent or modify primary infection for at least 9 years. Booster doses are not necessary during this period.

Child↗
PubMed1992

Pilot production of high-titer interferon and virus with a microcarrier suspension culture system.

We have successfully cultured four cell lines--L929, BHK-13, BHK-21 and CHO-K1 using an MC-1 type microcarrier made in our academy. With the microcarrier in a concentration of 5 mg/ml, the cell density was about 30 x 10(4) cells/ml; after 3 days in suspension culture, the cells could proliferate to 1 x 10(6) cells/ml. At this time, when L929 cells were primed with 25 IU/ml MuIFN for 14-24 h and then superinduced with NDV, cycloheximide (20 micrograms/ml) and actinomycin D (2 micrograms/ml), the titer of IFN reached approximately 10(5) IU/ml (10(5) IU/mg of protein, expressed in specific activity). When VSV was inoculated into the other three cell line cultures, the viral titer reached 6 Log TCID50/ml or much higher. The yield with the CHO-K1 cell line was the highest, reaching titers of 7-8 Log TCID50/ml. These titers were similar to those seen in stationary culture. With trypsin-citrate solution and a more rapid stirring speed, the cells could be satisfactorily released from the microcarriers and reattached on fresh ones. These experiments show that the microcarrier suspension culture system is suitable for producing large scale, high-titer, low-cost vaccines and IFNs, both natural and recombinant, using genetically-engineered CHO cell lines.

Animals↗
PubMed1991

[Effects of indomethacin in guinea pig cochlea: researches on audiology, morphology and cochlear blood flow].

Prostaglandins are known to be widely distributed in mammal tissues with diverse and potent biological activities. Indomethacin is a well-known cyclooxygenase inhibitor of prostaglandin synthesis. However, no paper appeared in the literature with regard to the effects of indomethacin on inner ear hearing function and cochlear lateral wall blood flow (LWBF). The present project was undertaken to investigate the effect of super-tolerated doses of indomethacin on audiology, morphology and LWBF of cochlea when that endogenous prostaglandin synthesis was greatly suppressed. In drug-treated group, super-tolerated doses of indomethacin (100 mg/kg) were given iv. to 29 guinea pigs. The compound action potentials (CAP) were monitored before and after drug administration till 180 minutes. The morphological changes of the organ of Corti were examined with scanning electron microscope, and that of stria vascularis with light and transmission electron microscopes. The LWBF were measured by biomicrosphere technique. The data were compared to those of the control group. Results showed no statistically significant changes of amplitude and threshold of CAP after indomethacin injection. No obvious morphological damage was found in the organ of Corti and stria vascularis except that a few of myelin figure were observed in marginal cell. LWBF was not decreased at 30 and 120 minutes after indomethacin injection. The study suggests that therapeutic doses of indomethacin do not damage cochlea, and inner ear hearing function is not severely interfered with when endogenous PGs synthesis is greatly suppressed, at least over the short time.

Animals↗
PubMed1991

[Isolation and characteristics of Borrelia burgdorferi from Ixodes persulcatus].

We reported the detailed characteristics of Lyme disease spirochetes (Borrelia burgdorferi), strain H7, isolated from Ixodes persulcatus in Heilongjiang. Cells of strain H7 were 9.8--26.5 microns long and 0.13--0.35 microns wide. There were 1--11 waves with a wavelength of 1.2--3.0 microns and an amplitude of 0.59--1.13 microns. Direction of spires was left. Seven flagella were inserted subterminally at each end of the cell and ends were pointed. 31 degrees C was the optimum cultural temperature in vitro. The major constitutional and antigenic proteins were 21k, 32k and 34k proteins. H7 could react on the patient sera of Xinjiang and Heilongjiang with IFA and western blot. These findings demonstrated that strain H7 belonged to species Borrelia burgdorferi, but was a new "subtype" which differed from the strains isolated from other areas and vectors.

Animals↗
PubMed1989

Protein kinase A and C activities and endogenous substrates in ovine small and large luteal cells.

Protein kinase A (cAMP-dependent) and C (calcium, phospholipid-dependent) activities were measured and in vitro phosphorylation of endogenous proteins by these kinases were observed by SDS-PAGE in 100,000 x g supernatant (soluble) fractions of ovine small (12-22 microns) and large (greater than 22 microns) luteal cells. No differences in stimulation (P less than 0.05) of A kinase activity between small and large cells were detected. Protein kinase C activity was stimulated (P less than 0.05) 2.9-fold in small cells but not significantly enhanced above basal (P greater than 0.05) in large cells. By direct comparison, greater stimulation (P less than 0.05) over basal of A versus C kinase (6.1- versus 2.9-fold) was measured in small cells. These stimulations were greater than those observed in large cells (A kinase, 4.8-fold; C kinase, 1.8-fold). Maximal specific activities of both kinases (per mg protein) were greater (P less than 0.05) in small than in large cells. Endogenous proteins that could serve as substrates for phosphorylation by A and C kinases differed between small and large cells. Phosphorylation of six proteins by A kinase was consistently greater in small than in large cells. One endogenous protein (37 kDa) appeared to serve as a preferred substrate for phosphorylation by A kinase in small cells and C kinase in large cells. One protein (81 kDa) was predominantly phosphorylated in large rather than small cells by a calcium-dependent, C kinase-independent mechanism. These results support the accepted role of cAMP via A kinase and a possible role for C kinase in regulating steroidogenesis in ovine small luteal cells. The inability of large cells to respond to cAMP with enhanced secretion of progesterone may be due to an unavailability of phosphoprotein substrates for A kinase. Furthermore, protein kinase C activity and available protein substrates display quantitative and qualitative differences between small and large cells. Differences in regulation of steroidogenesis between the cell types may be due to these observed differences.

Animals↗
PubMed1989

Luteotropic and luteolytic responsiveness of ovine luteal cells in long-term culture.

Ovine luteal cells were collected and plated 36 h (Day 2) after injection of human chorionic gonadotropin (Day 0) to induce ovulation. Cells were maintained (Days 2-12) in Medium 199 containing 5% calf serum, which was replaced daily. Progesterone secretion was not stimulated (p greater than 0.05) by luteinizing hormone (LH, 10 ng/ml or 100 ng/ml) at any time during culture. However, it was enhanced (p less than 0.05) with a 24-h pulse of dibutyryl adenosine 3', 5'-monophosphate (dbcAMP) during early (2.2-fold stimulation over basal; Days 5,6) or mid- (1.7-fold stimulation over basal: Days 8,9) culture if the pulsing medium contained serum, but not if serum had been withdrawn for 24 h. Continuous exposure of cultures to dbcAMP (2 mM, Days 3-12) resulted in continuously stimulated (p less than 0.05) progesterone secretion (range 1.8- to 4.1-fold stimulation). An increased (p less than 0.05) percentage of cells staining positive for 3 beta-hydroxy-delta 5-steroid dehydrogenase-delta 5, delta 4-isomerase (3 beta HSD) activity were recovered on Day 12 in cultures incubated (Days 3-12) with dbcAMP. Incubation of cultures continuously with prostaglandin F2 alpha (PGF2 alpha) produced dose-dependent inhibition (p less than 0.05) of progesterone secretion. Reduced numbers of 3 beta HSD-positive cells were recovered from these incubations. These experiments demonstrate luteotropic (dbcAMP) as well as luteolytic (PGF2 alpha) effects on ovine luteal cells in long-term culture. This study provides evidence that these cultures will be useful for investigating the development of hormonal regulation of luteal function.

Animals↗
PubMed1988

Steroidogenic capacity and ultrastructural morphology of cultured ovine luteal cells.

Corpora lutea were surgically collected from superovulated ewes 36 h post-injection of human chorionic gonadotropin (hCG) (Day 2), dissociated (0.2% collagenase), plated, and maintained in culture Days 2-10 in Medium 199 supplemented with 5% calf serum. Accumulation of progesterone in the cultures did not decrease (p greater than 0.05) from Day 3 (17.5 +/- 5.1 nmol/10(6) cells) to Day 10 (4.8 +/- 1.7 nmol/10(6) cells). Calf serum (5%) in the medium supported greater (p less than 0.05) progesterone production than fetal calf serum (5%) or medium without added serum. Steroidogenic cells did not increase (Days 2-10) in numbers, but increased (p less than 0.01) in mean cell diameter (Day 2, 11.7 +/- 0.4 micron; Day 10, 24.5 +/- 1.6 micron). Steroidogenic capacity on Day 10 of cells cultured Days 2-10 (in vitro) was not different (p greater than 0.05) from that of cells collected from the ovary on Day 10 (in vivo); however, steroidogenic cells recovered from plates had greater (p less than 0.01) mean cell diameters (24.5 +/- 1.6 micron, in vitro, compared to 15.2 +/- 1.0 micron, in vivo). Transmission electron microscopy revealed that cultured cells (Days 5, 10) possessed less smooth endoplasmic reticulum but more lipid droplet inclusions, ribosomes, and rough endoplasmic reticulum than cells obtained in situ (Day 10). Electron-dense secretory granules were rarely seen. Although subcellular morphology of ovine luteal cells in culture was altered, these changes did not appear to significantly affect the ability of these cells to produce progesterone.

Animals↗