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Biomedical subjects

F H Lin

Publications and source records attributed to F H Lin.

At least 55 records · Page 3Linked to original sources
PubMed1997

The preliminary study and tentative animal study on the sintered PDLLA/TCP composites as bone fracture internal fixation.

Polyesters based on the lactic acid have been reported safety and biodegradation in the human beings for two decades. The greatest advantage of the material is its degradation only conducted by the hydrolysis, where the ester backbones are supposed to be unchained in the aqueous condition. The final degradable products are carbon dioxide and water which can be metabolized and digested in the physiological environment. The goal of this study was aimed to develop a composite sintered with poly-DL-lactide (PDLLA) and tricalcium phosphate (TCP) ceramic particles as orthopedic application. The TCP particles in a range of 30-60 wt% (with 5 wt% increment) were doped into the PDLLA matrix for the reinforcement, which were prepared by the melting and hot pressing techniques. The basic mechanical strength, biodegradable behavior, and biological response of the composites will be investigated in the study. Various techniques, such as pH meter, UV, FTIR, XRD ect., were used to examine and record the degradable process of the composites soaked in the saline for 1-16 weeks. The rabbit femur condyle fracture fixation test was used to evaluate the tissue compatibility and the effects of bone fracture fixation of the composites. The histological observation and x-ray photography were applied for investigating assistance. In the histological evaluation of rabbit femur condyle fracture fixation test, the surface of the composite with 50 wt% TCP addition was attached by the new generated bone without fibrous tissue around after 8 weeks implantation. The fracture bone was gradually healing and the composite always firmly and properly fixed on the fracture area during the implanted period, which provided a breeding environment for normal bone remodeling. The developed composite was thought to be an alternative material for orthopedic application in the future, especially in bone screw and bone plate.

Animals↗
PubMed1996

Prevascularized bone graft cultured in sintered porous beta-Ca2P2O7 with 5 wt% Na4P2O7.10H2O addition ceramic chamber.

Autogenous bone transfer is an important part of reconstructive plastic surgery. Presently available techniques have the disadvantages of limitation of available donor site, loss of donor tissue and the possibility of donor defect or deformity. In the present study, a vascularized bone graft was created and cultured in the groin area of the New Zealand rabbit. The cylindrical ceramic chambers, 15 mm in length, 6 mm in outer diameter and 3 mm in inner diameter, were prepared by the addition of sintered porous beta-Ca2P2O7 with 5 wt% Na4P2O7.10H2O. In the first group, the chambers impregnated with autogenous bone fragments and allogenous demineralized bone matrix with volume ratio 1:1 were cultured in the rabbit's groin area with saphenous vessels passing through. In the second group, the chambers were treated by the same procedures as the first group but without saphenous vessels passing through. In the third group, the chambers were not impregnated, and were cultured in the groin area with saphenous vessels. After 2, 4, 6, 8 and 12 wk of operation, the animals were killed with an overdose of intravenous pentobarbital. The viability of the osseous tissue in the chamber was evaluated by histological examination, microangiograms and fluorochrome incorporation for the three groups. The autogenous bone chips could survive and retain their osteogenic properties while packed into the sintered porous beta-Ca2P2O7 (with 5 wt% Na4P2O7.10H2O addition) ceramic chamber and implanted in the rabbit groin area up to 12wk. However, even at the longest time periods, considerable amounts of dead bone were present in the chambers. In addition, we observed bone resorption in the three groups up to 12 wk, which might be attributed to lack of physiological stress. There were significant differences in new bone formation and osseous cell viability among the three groups. The prevascularized vessels and autogenous bone chips were both necessary for the formation of new bone and osteogenic property in the chamber under these heterotopic circumstances. The biodegradable ceramic used in this study was gradually absorbed and dissolved in the physiological environment. However, the degradation debris of the ceramic caused no injury to the new bone formation. These findings support the concept of creating a preformed vascularized bone graft to reconstruct segmental bone defects.

Animals↗
PubMed1995

Mechanical properties and histological evaluation of sintered beta-Ca2P2O7 with Na4P2O7.10H2O addition.

The ultimate goal of implantation of biomaterials in the skeleton is to reach full integration of the non-living implant with the living bone. The biomaterial can be used much as a bone graft, resorbing or dissolving as bone growth occurs, and the end result is a new remoulded bone. Calcium pyrophosphate, Ca2P2O7, is one of the intermediate products of bone mineralization. beta-Dicalcium pyrophosphate (beta-DCP) doped with certain amounts of Na4P2O7.10H2O was prepared as the developed material. Na4P2O7.10H2O was used as a liquid-phase additive to improve the sintering process and promote physiological bioresorbability. Compressive strength and four-point bending strength were measured by the Bionix test system 858. The mechanical strength of the sintered beta-DCP increased with the addition of Na4P2O7.10H2O up to 5 wt%, but thereafter decreased. The microstructure and crystal structure were analysed by the techniques of SEM, EPMA, TEM and XRD. The relationship between the mechanical strength of the sintered bioceramics and the Na4P2O7.10H2O dopant was examined in terms of the presence of NaCa(PO3)3, grain growth and abnormal grain coalescence while the dopant increased. Preliminary in vivo evaluation was studied by rabbit femur condyle implantation. There was no inflammation or any toxic sign during the experimental period. The histological section of intraosseous implantation revealed that the new bone deposited directly on the surface of the material in the fourth week after operation. The implant gradually decreased in volume and was replaced by the surrounding regenerated bone in the rabbit condyle in vivo environment. The results led us to conclude that the developed material has great potential as a biodegradable bone substitute.

Animals↗
PubMed1995

The effects of ultrasonic stimulation on DP-bioglass bone substitute.

In previous studies, DP-bioglass showed good biocompatibility and can form a chemical bond with natural bone. After implementation in the rabbit femur condyle for 32 weeks, DP-bioglass gradually biodegraded and osteocytes grew into the material. In this study, an attempt has been made to utilize low intensity pulsed ultrasound to speed up the bone regeneration rate and DP-bioglass absorption rate when the DP-bioglass is implanted into the rabbit femur condyle as a bone substitute. The fundamental parameters of the ultrasound used were 1.5 MHz frequency, 0.5 W cm-2 intensity, on-off ratio 1:1 and 2 ms for the on-off time interval. The stimulation, in all cases, was started 24 h after the operations by applying the transducer to the skin using DIR ultrasound jelly as a coupling medium. The evaluation of the progress of bone regeneration and the material's biodegradable rate were conducted by histological examination and by measurements of the areas of regenerated bone, pores and DP-bioglass made with a planimeter. It was found that low intensity pulsed ultrasound had a profound effect on the rate both of bone regeneration and DP-bioglass bioabsorption in this rabbit model and that its mechanism of the action may be via an electromechanical kinetic effect on the cell membrane interfaces.

Animals↗
PubMed1995

GABAB receptor-mediated effects in synaptosomes of lethargic (lh/lh) mice.

Previously, we have shown a significant increase in number of GABAB receptor binding sites in neocortex and thalamus of lethargic (lh/lh) mice, a mutant strain exhibiting absence seizures. This study was performed to test our hypothesis that presynaptic GABAB receptors would inhibit [3H]GABA release to a greater degree in lh/lh mice compared with their nonepileptic littermates (designated +/+). Synaptosomes isolated from neocortex and thalamus of age-matched male lh/lh and +/+ mice were similar in uptake of [3H]GABA. In the neocortical preparation, baclofen dose-dependently inhibited [3H]GABA release evoked by 12 mM KCl, an effect mediated by GABAB receptors. The maximal inhibition (Imax) value was significantly greater (80%) in lh/lh than +/+ mice, whereas the IC50 (3 microM) was unchanged. In the thalamic preparation, the effect of baclofen (50 microM) was 58% less robust in lh/lh mice. Other effects mediated by GABAB receptors (inhibitions in Ca2+ uptake and cyclic AMP formation) were also significantly reduced in thalamic synaptosomes from lh/lh mice. These data suggest a greater presynaptic GABAB receptor-mediated effect in neocortex and a reduced effect in thalamic nuclei of lh/lh mice. It is possible that selective effects of presynaptic GABAB receptors or GABA release in neocortex and thalamic nuclei of lh/lh mice may contribute to mechanisms underlying absence seizures.

Animals↗
PubMed1995

Neural network of structures in which GABAB receptors regulate absence seizures in the lethargic (lh/lh) mouse model.

In previous work we have shown that GABAB receptors are required for expression of absence seizures in the lethargic (lh/lh) mouse model; that lh/lh mice have increased numbers of GABAB binding sites compared to nonepileptic littermates (designated +/+); and that the magnitude of the increased number of GABAB receptors in lh/lh mice correlated positively with the frequency of absence seizures. We performed this study to delineate the neural network in which GABAB receptors regulate absence seizures in lh/lh mice. We designed three successive screens which had to be passed by a candidate neuronal population before it could be considered a member of the neural network in which GABAB receptors regulate absence seizures. First, the neuronal populations in lh/lh mice had to have enriched GABAB binding sites compared to homologous populations in matched nonepileptic controls; baclofen-displaceable 3H-GABA binding was measured in autoradiograms for this screen. Second, the candidate populations had to generate spike-wave discharges (SWDs) during absence seizures in lh/lh mice; bipolar recording electrodes implanted into candidate neuronal structures were used in this screen. Third, the candidate populations had to demonstrate GABAB receptor-mediated regulation of absence seizures in lh/lh mice; microinjections of a GABAB agonist [(-)-baclofen] and antagonist (CGP 35348) were used for this screen. In this study we found that anterior ventral lateral thalamic nucleus (VLa), nucleus reticularis thalami (NRT), nucleus reuniens (RE) passed all three screens, and hence are members of the neural network in which GABAB receptors regulate absence seizures in lh/lh mice.

Animals↗
PubMed1994

Sintered porous DP-bioactive glass and hydroxyapatite as bone substitute.

There is extensive experimental and surgical experience with the use of bone tissue to fill defects in the skeleton, to bridge non-union sites, and to pack defects in bone created from cyst curettage. DP-bioactive glass with a chemical composition of Na2O 8.4%, SiO2 39.6%, P2O5 12% and CaO 40% has been reported as an alternative bone substitute of high mechanical strength, good biocompatibility. and which has a tight bond with living tissue. The bonding layer between DP-bioactive glass and bone tissue was considered to be formed by dissolution of calcium and phosphate ions from the DP-bioactive glass into the surrounding body fluids. The biological hydroxyapatite was suspected to deposit directly onto the bonding layer. In order to confirm the interaction between the DP-bioactive glass and bone tissue, the developed bioactive glass was implanted into rabbit femur condyle for 2-32 weeks. The histological evaluation of DP-bioactive glass as a bone substitute was also investigated in the study. Porous hydroxyapatite bioceramic was used in the control group and the results were compared with those of DP-bioactive glass. The interface between the DP-bioactive glass and bone tissue examined with SEM-EPMA showed that the bioactive glass formed a reaction layer on the surface within 2 weeks after operation and formed a direct bond with natural bone. The elements contained in the bioactive glass apparently interdiffuse with the living bone and biological hydroxyapatite deposited onto the diffusion area, which was proved by EPMA and TEM. After implantation for over 8 weeks, the DP-bioactive glass was gradually biodegraded and absorbed by the living bone. Histological examination using the optical microscope showed that osteocytes grow into the inside of the DP-bioactive glass and the bioactive glass would be expected to be a part of bone.

Animals↗
PubMed1993

Increased number of GABAB receptors in the lethargic (lh/lh) mouse model of absence epilepsy.

This study begins to explore possible mechanisms underlying the role of GABAB receptors in absence seizures in lethargic (lh/lh) mice. To test the hypothesis that alterations intrinsic to the GABAB receptor underlie enhanced synaptic activation of these receptors in absence seizures, we measured GABA-displaceable [3H]baclofen binding to neocortical plasma membranes prepared from lh/lh and wild (+/+) age-matched congenic mice. The number (Bmax) of binding sites was significantly greater (20%) in lh/lh (4.2 pmol/mg protein, n = 43 pairs, P < 0.02) than in +/+ mice (3.3 pmol/mg protein) in an age-independent manner. Interestingly, the subset of lh/lh mice with greater seizure frequency (40-70 seizures/15 min, measured by bipolar electrodes implanted into neocortex; n = 11) had a significantly greater Bmax (P < 0.003) than the subset with lower seizure frequency (1-10 seizures/15 min; n = 11). The equilibrium dissociation constant (Kd) was unchanged (60 nM in both). The Kd of both strains was inhibited to an equal degree by the nonhydrolysable GTP analogue 5'-guanylimido-diphosphate [Gpp(NH)p]. The increased number of GABAB binding sites was selective, because binding to NMDA sites ([3H]glutamate binding) and to GABAA sites ([3H]muscimol binding) was not significantly different in the two strains. These data suggest that the increased number of GABAB receptors in lh/lh mice underlies enhanced synaptic activation of these receptors. Together with evidence that GABAB receptor activation can produce disinhibition, our data support a role for GABAB receptors in the expression of absence seizures in lh/lh mice.

Animals↗
PubMed1993

Preparation and in vivo evaluation of a newly developed bioglass ceramic.

This paper presents details of the fabrication of a glass ceramic, and its application as an artificial bone prosthetic material. This new bioglass ceramic, with composition of Na2O 8.4%, CaO 40.6%, P2O5 12% and SiO2 39%, had 160-190 MPa and 800-980 MPa of three-point bending strength and compressive strength respectively. The ceramic has a (Na, Ca) (P, Si) O3 crystalline phase with a uniform crystal size of about 10 microns, which was attributed to the high nucleation frequency. The rabbit condyle test showed that the material formed a tight chemical bond with biological texture and had good biocompatibility.

Animals↗
PubMed1992

A comparison of single nucleotide primer extension with mispairing PCR-RFLP in detecting a point mutation.

A recent report by Petruzzella et al. (BBRC 186, 491-497, 1992) raised a question as to whether a point mutation in the mitochondrial ND2 gene (BBRC 182, 238-246, 1992) is relevant to Alzheimer's disease. The argument was based on their inability to detect the point mutation at position 5460 in codon 331 in the DNAs extracted from 15 patients with Alzheimer's disease using mispairing PCR-RFLP. To clarify the discrepancy, we tested the DNAs reported by Petruzzella et al. for the mutation by single-nucleotide primer extension. The present work confirms our previous report and extends our finding of the point mutation in 8 of the 15 AD DNAs.

Aged↗
PubMed1992

The role of GABAB receptor activation in absence seizures of lethargic (lh/lh) mice.

Lethargic (lh/lh) mice, which function as an animal model of absence seizures, have spontaneous seizures that have behavioral and electrographic features and anticonvulsant sensitivity similar to those of human absence seizures. Antagonists of the gamma-aminobutyric acidB (GABAB) receptor suppressed these seizures in lethargic mice, whereas agonists of GABAB receptors exacerbated them. Furthermore, GABAB receptor binding and synaptically evoked GABAB receptor-mediated inhibition of N-methyl-D-aspartate responses were selectively increased in lh/lh mice. Therefore, enhanced GABAB receptor-mediated synaptic responses may underlie absence seizures in lh/lh mice, and GABAB receptor antagonists hold promise as anticonvulsants for absence seizures.

Animals↗
PubMed1992

Detection of point mutations in codon 331 of mitochondrial NADH dehydrogenase subunit 2 in Alzheimer's brains.

Point mutations in codon 331 of mitochondrial NADH dehydrogenase subunit 2 (ND2) were detected in 10 of 19 Alzheimer's brains but not in 11 normal brains. The same mutations were also detected in 2 of 6 patients with amyotrophic lateral sclerosis (ALS). However, neurofibrillary tangles and neuritic plaques characteristic of Alzheimer's disease were found histologically in the brain of one ALS patient who was positive of the mutation. The finding suggests that a point mutation in ND2 is a potential risk factor for Alzheimer's disease.

Adult↗
PubMed1991

The effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the hepatic estrogen and glucocorticoid receptors in congenic strains of Ah responsive and Ah nonresponsive C57BL/6J mice.

The present study examines the role of the Ah receptor in the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the binding capacity of the hepatic glucocorticoid (GC) and estrogen (E) receptors in female congenic C57BL/6J mice differing only at the Ah (aromatic hydrocarbon responsiveness) locus. The Ah locus is thought to encode the Ah receptor, which regulates the effects of TCDD and related compounds on cytochrome P450IA1 and appears to mediate most of the toxic effects of TCDD. The differences between Ah responsive (Ahb/b) and nonresponsive (Ahd/d) mice appear to reflect differences in the affinity of the Ah receptor in the two strains for ligands such as TCDD. Administration of a single oral dose of TCDD (30 micrograms/kg) to Ahb/b mice produced approximately a 30% decrease in the maximum binding capacities of both the hepatic GC and E receptors, as well as 50-fold induction of a P450IA1-mediated enzymatic activity, ethoxyresorufin-O-deethylase (EROD). Tyrosine aminotransferase (TAT) activity, which is mediated by the GC receptor, was also decreased approximately 30% by TCDD. Dose-response curves indicated that Ah responsive mice are 10-fold more sensitive to induction of EROD than Ah nonresponsive mice (ED50 1.6 vs 15 micrograms/kg), as would be expected for an effect mediated by the Ah receptor. Dose-response curves also indicated that there was a statistical difference in the responsiveness of the hepatic E receptor to TCDD in the two congenic strains of mice (p less than 0.01). Surprisingly, no significant differences in the dose-response curves for the effect of TCDD on hepatic GC receptor binding or TAT activity were observed in the two strains of mice in two separate experiments. These results indicate that the Ah receptor regulates the effects of TCDD on the binding of estrogen to the hepatic estrogen receptor, but suggest that the decrease in the binding capacity of the hepatic GC receptor does not appear to be mediated directly by the Ah locus.

Animals↗
PubMed1991

Fabrication and biocompatibility of a porous bioglass ceramic in a Na2O-CaO-SiO2-P2O5 system.

A porous bioglass ceramic was prepared from a finely pulverized bioglass powder mixed with particles of two sizes (5 and 500 microns) of 30% by weight with the foaming agent polyethylene glycol 4000 (HO (C2H4O) nH). The batch composition of the bioglass was Na2O 12%, CaO 28%, SiO2 50% and P2O5 10% by weight. The specimens, formed by pressing, were sintered in a high temperature furnace. In this study we are concerned with the preparation and microstructure of the material and its performance in biological tests. The microstructure and crystalline phases of the material were investigated by differential thermal analysis, X-ray diffraction analysis, transmission electron microscopy and scanning electron microscopy. In a biomedical examination, it was shown that the porous material was compatible with animal tissues. The microstructure of the implant indicated that newly grown bone interlocked well with the glass ceramic and that macropores and micropores were distributed uniformly in the material, which provided channels for bone ingrowth and improved the microscopic bioresorption.

Animals↗
PubMed1991

Influence of the Ah locus on the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on the hepatic epidermal growth factor receptor.

The present studies examine whether the Ah receptor mediates the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the binding capacity of the hepatic epidermal growth factor (EGF) receptor in congenic strains of C57BL/6J mice that differ only at the Ah locus. The Ah locus is believed to encode the Ah receptor, which mediates the induction of cytochrome P4501A1 by TCDD and appears to mediate many of the toxic effects of TCDD. TCDD produced an 80-90% decrease in the maximum binding capacity (both high and low affinity sites) of the hepatic EGF receptor in female Ah-responsive (Ahb/b) and Ah-nonresponsive (Ahd/d) C57BL/6 mice. However, the ED50 for the effects of TCDD on the binding capacity of the EGF receptor was 10-fold higher in the Ah-nonresponsive mice, compared with the Ah-responsive mice (7 versus 0.7 micrograms/kg). TCDD did not affect the hepatic content of two EGF receptor mRNA transcripts (10 and 6 kb), indicating that the effects on the EGF receptor are not pretranslational. Similarly, TCDD did not affect the hepatic content of mRNA for transforming growth factor-alpha, an alternate ligand for the EGF receptor that is synthesized in the liver. In contrast, TCDD markedly increased the hepatic content of the mRNA for cytochrome P4501A1, which is known to be regulated transcriptionally by TCDD. The ED50 for this effect was 10-fold higher in Ah-nonresponsive mice than in Ah-responsive mice (13 versus 1.3 micrograms/kg). This study indicates that the effects of TCDD on EGF receptor ligand binding are mediated by the Ah receptor. However, unlike the effect of TCDD on cytochrome P4501A1, the effects of TCDD on the EGF receptor do not involve changes in the levels of the mRNA for this protein or changes in the mRNA for transforming growth factor-alpha, an alternate ligand for the EGF receptor.

Animals↗
PubMed1990

Induction of ethoxyresorufin-O-deethylase and inhibition of glucocorticoid receptor binding in skin and liver of haired and hairless HRS/J mice by topically applied 2,3,7,8-tetrachlorodibenzo-p-dioxin.

The biochemical changes associated with the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) have been reported to include alterations in glucocorticoid and epidermal growth factor receptors and mixed function oxidase (MFO) induction. TCDD induces MFO activity in skin of both haired and hairless HRS/J mice. However, epidermal hyperplasia and hyperkeratosis are produced only in the skin of hairless mice. Therefore, since steroid and growth factor responses are implicated in cell proliferation and differentiation, these mice constitute a model system for assessing the possible roles of glucocorticoid and epidermal growth factor receptors in the toxicity of TCDD. The effect of dermal TCDD application (12 micrograms/kg in 100 microliters acetone) on ethoxyresorufin-O-deethylase (EROD) activity, glucocorticoid receptor binding and epidermal growth factor receptors in liver and skin of hairless and haired mice was determined. No differences existed in the basal number of cytosolic glucocorticoid receptors (Bmax) or the apparent equilibrium binding constants (Kd) in control liver, dorsal skin and abdominal skin of male and female hairless mice and haired male mice. Seven days after topical application of TCDD, decreases of approximately 38% were observed in the hepatic Bmax of the glucocorticoid receptors in both haired and hairless mice. However, in dorsal skin, TCDD decreased Bmax by approximately 40% in hairless mice but only 18% in haired mice. The dexamethasone-glucocorticoid receptor complex from both liver and skin of control and TCDD treated mice had similar sedimentation co-efficients in sucrose density gradients. TCDD had no effect on the Kd of glucocorticoid receptors of skin or liver in haired and hairless mice. No difference was observed in the time-dependent increases in hepatic EROD activity between haired and hairless mice after dermal application of TCDD. However, the maximum induction of EROD activity in microsomes from the skin of haired mice was only 60% of the activity observed in hairless animals. The induction of EROD by TCDD did not correlate temporally with the decrease in glucocorticoid receptor binding. The application of TCDD to the skin of hairless mice resulted in epidermal hyperplasia and dermal keratinization, while little change was observed in the general morphology of the skin of haired mice following dermal application. The application of TCDD had no effect on the incidence and distribution of epidermal growth factor receptors in skin of haired and hairless mice as determined immunohistochemically. Thus, the biochemical effects of TCDD are not only strain dependent, but tissue specific. Furthermore, decreases in glucocorticoid and epidermal growth factor receptors do not appear to be general markers of TCDD toxicity.

Animals↗
PubMed1988

Catabolism of 5-fluoro-2'-deoxyuridine by isolated rat intestinal epithelial cells.

The kinetics of conversion of 5-fluoro-2'-deoxyuridine (FdUrd) to 5-fluorouracil (FUra) by isolated rat intestinal epithelial cells was investigated. Also, the effects of potential inhibitors of this reaction, which is catalyzed by uridine phosphorylase and thymidine phosphorylase, were determined. A 2.5% suspension of isolated cells was incubated with FdUrd or FUra, and at specific times cells were lysed with perchloric acid and fluoropyrimidines were determined by high-performance liquid chromatography. During a 25-min incubation with either FdUrd or FUra, the amount of drug in the incubation system (total volume 0.8 ml) fell by less than 5%. However, in the presence of FdUrd, the amount of FUra increased linearly over 25 min. The apparent Vmax and Km for FUra formation were 17-27 nmole/mg DNA/min and 1.6-2.5 mM, respectively. With each nucleoside phosphorylase inhibitor, the apparent Km increased but Vmax was unaffected. The apparent Ki values were as follows (in mM): 5-nitrouracil (an inhibitor of both uridine phosphorylase and thymidine phosphorylase), 0.12; 4-thiothymine (a uridine phosphorylase-selective inhibitor), 1.52; and 6-benzyl-2-thiouracil (a thymidine phosphorylase-selective inhibitor), 0.73. It was concluded that intestinal epithelial cells are capable of degrading FdUrd to FUra and that the cells possess both uridine phosphorylase and thymidine phosphorylase activity.

Animals↗