Biomedical subjects

Y Chen

Publications and source records attributed to Y Chen.

At least 433 records · Page 24Linked to original sources

PubMed2001

Measurement of membrane potential and intracellular Ca(2+) of arteriolar endothelium and smooth muscle in vivo.

We have developed an intensity analysis technique for fluorescence microscopy that allows us to measure, in real time, the diameter and the membrane potential or intracellular calcium ([Ca(2+)]i) of in vivo arteriolar endothelium or smooth muscle. Cheek pouch arterioles of anesthetized hamsters were luminally or abluminally labeled with Di-8-ANEPPS, a voltage-sensitive dye, or Fura PE3, a calcium indicator. The peak fluorescence intensities of the images were used to locate the endothelium or smooth muscle. The changes in membrane potential or [Ca(2+)]i were determined based on the ratiometric analysis of fluorescence intensity of the endothelium or smooth muscle. Membrane depolarization of the smooth muscle using KCl caused a decrease in the ratio of emission, 620 nm/560 nm ( approximately 6 mV/% ratio). The ratio of excitation, 340 nm/380 nm, increased with increasing free Ca(2+). Methacholine, a muscarinic receptor agonist, caused arteriolar dilation (12.2 +/- 0.9 &microm). It produced hyperpolarization of the endothelium and smooth muscle (2.8 +/- 0.6% and 2.3 +/- 0.3% in ratio). Methacholine also induced an increase in [Ca(2+)]i (11.0 +/- 1.1% in ratio) of the endothelium. In contrast, methacholine caused a biphasic change in [Ca(2+)]i of the smooth muscle, a rapid reduction (-3.4 +/- 0.2% in ratio) followed by a prolonged increase (2.4 +/- 0.2% in ratio). These results demonstrate that the peak intensity analysis can be used to determine in real time the changes in membrane potential or [Ca(2+)]i of in vivo endothelium or smooth muscle.

Animals↗

PubMed2001

Investigation on marking method for phenomenon on regrowth drug resistance in relapsed acute myelogenous leukemia.

A method for evaluating the regrowth drug resistance in relapsed acute myelogenous leukemia (AML) was developed. Drug sensitivity and proliferation of leukemic cells in vitro were determined using leukemic cell colony forming unit (CUF-L), MTT drug-sensitive test, percentage of S phase cells in cell cycle (S%), fluorescent index (FI) and drug resistant index (DRI) by detecting intracellular daunorubicin, expression of P-170 glycoprotein by APAAP assay, and abundance of Bcl-XL mRNA by semiquantitative reverse transcription polymerase chain reaction (RT-PCR) methods. First, the correlation between scoring criteria and cell drug resistance and cell proliferation was investigated in newly untreated AML patients. Second, 20 patients with relapsed AML were marked. According to each tested result, its point(s) was scored. The results showed that among the 20 cases of relapsed AML, 9 were diagnosed as having regrowth drug resistance. It was concluded that the scoring method for regrowth drug resistance was first developed in AML. There was regrowth drug resistance in relapsed AML; clinically circumventing it would be of extreme significance for establishment of new approaches to the treatment in AML.

ATP Binding Cassette Transporter, Subfamily B↗

PubMed2001

The role of nitric oxide in hyperoxic lung injury in premature rats.

To investigate the role of nitric oxide (NO) in hyperoxic lung injury, the 3-day-old preterm rats were randomly assigned to four groups: group I (hyperoxia group), group II (hyperoxia + Nw-nitro-L-arginine methyl ester (L-NAME) group), group III (air group), and group IV (air + L-NAME) group. Group I and II were exposed to > or = 90% O2 for 3 or 7 days. Group II and IV received subcutaneous L-NAMEy on daily basis (20 mg/kg). After 3 day or 7 day exposure, the lung wet weight/dry weight ratio (W/D), total protein and malondialdehyde (MDA) in bronchoalveolar lavage fluid (BALF) and lung pathology were examined in all groups. NO content, expression of endothelial NOS (eNOS) and inducible NOS (iNOS) in lungs were measured in group I and III. Our results showed that after 3 day exposure, group I appeared acute lung injury characterized by the increase of MDA content (P < 0.01) and the presence of hyperaemia, red cell extravasation and inflammatory infiltration; after 7 day exposure, except MDA, total protein and W/D were also increased in comparison with group III (P < 0.01, 0.05), pathological changes were more severe than those after 3 day exposure. After 3 and 7 day exposure, total protein in group II was significantly increased as compared with group I (P < 0.01 for both). The pulmonary acute inflammatory changes were more obvious in group II than in group I. Occasionally, mild hemorrhage was detected in the lungs of group IV. BALF protein content in group IV was higher than that in group III after 7 day exposure (P < 0.01). After 3 and 7 day exposure, NO content in BALF were all significantly elevated in group I as compared with group III (P < 0.01 for all). In the lungs of group I, strong immunostaining for iNOS was observed in airway and alveolar epithelia, inflammatory cells, which were stronger than those in group III. Expression of iNOS in rats after 7 day hyperoxic exposure was stronger than that after 3 day exposure. Shortly after 7 day exposure, stronger immunostaining for eNOS in airway epithelia in group I than that in group III was seen. Our study suggested that treatment with L-NAME worsened acute hyperoxic lung injury in preterm rats and also had a deleterious effect on the rats exposed to air, indicating that endogenous nitric oxide may play a protective role in rats under both physiological and hyperoxic status. Hyperoxia can significantly upregulate the expression of iNOS and eNOS in inflammatory cells, epithelia in the lungs of preterm rats, promote NO generation, which suggests that endogenous NO may mediate the hyperoxic pulmonary damage. Over-stimulation of iNOS may contribute to the pathogenesis of hyperoxic lung injury. NO may have dual roles in pulmonary oxygen toxicity.

Animals↗

PubMed2001

Computer measurement of oral movement in swallowing.

This article describes a computer program that automatically detects and tracks small metal markers affixed to a subject's tongue and teeth in fluoroscopic image sequences of swallowing. The program, written in Microsoft Visual C++ using Windows NT 4.0 and the SAVANT imaging toolkit, involves marker detection and marker tracking. Marker detection is done by template matching. A generic marker template was designed by extracting the grayvalues of pixels within an imaged marker. Template matching with a weighted center-of-mass calculation determined marker location with subpixel accuracy. Marker tracking employed a nearest-neighbor algorithm since (a) the movement of each marker was less than the distance between any two markers and (b) marker trajectories did not overlap. Effects of head motion were attenuated by computing tongue trajectories with respect to a constant frame of reference given by reference markers on the maxillary teeth. Motions were converted from pixels/frame to millimeters/second using a calibration ring secured to the subject's neck. Results for several image sequences showed that our program performs very well in terms of marker detection and trajectory determination. Comparison of automatic and manual tracking of the same image sequences indicated a high degree of correspondence. Automatic tracking of oral movement by computer is a useful tool in kinematic studies of swallowing.

Algorithms↗

PubMed2001

Comparison between hypothermia and glutamate antagonism treatments on the immediate outcome of perinatal asphyxia.

This study investigated the influence of temperature or glutamate antagonism on the immediate outcome of perinatal asphyxia. Perinatal asphyxia was produced by water immersion of fetus-containing uterus horns removed by cesarean section from ready to deliver rats. The uterus horns were kept in a water bath for different time periods, before the pups were delivered and stimulated to breathe. After delivery, the pups were assessed for behavior and for systemic glutamate, aspartate, lactate and pyruvate levels measured with in vivo microdialysis, or ex vivo for energy-rich phosphates, including adenosine triphosphate (ATP), in brain, heart and kidney. In a series of experiments, asphyxia was initiated in a water bath at 37 degrees C, before the pup-containing uterus horns were moved for different time intervals to a 15 degrees C bath. In another series of experiments, the mothers were treated with N-methyl-D-aspartate (NMDA) antagonist, dizocilpine (MK-801), or alpha-amino-3-hydroxy-methylisoxazole-4-propionic acid (AMPA) antagonist,2,3-dihydroxy-6-nitro-7-sulfamoyl benzo(f) quinoxalin NBQX) 1 h before hysterectomy and asphyxia at 37 degrees C. The rate of survival rapidly decreased following exposure to more than 16 min of asphyxia, and no survival could be observed after 22 min of asphyxia. An LD50 was estimated to occur at approximately 19 min of asphyxia. The outcome was paralleled by a decrease in ATP in kidney, followed by a decrease in heart and brain. A maximal decrease in ATP was observed after 20 min of asphyxia in all tissues. Systemic microdialysis revealed that glutamate, aspartate and pyruvate levels were increased with a peak after 5 min of asphyxia. In contrast, lactate levels increased along with the length of the insult. Survival was increased when the pup-containing uterus horns were moved from a 37 degrees C to a 15 degrees C bath, at 15 min of asphyxia (the LD50 was thus increased to 30 min). If the shift occurred at 10 or 5 min of asphyxia, the LD50 increased to 80 or 110 min, respectively. The effect of glutamate antagonism was minor compared to hypothermia; the best effect (an increase in the LD50 to approximately 22 min) was observed after combining AMPA and NMDA antagonists.

Adenosine Triphosphate↗

PubMed2001

4',6-diamidino-2-phenylindole (DAPI) interacts with rare structures of GC polymers.

The binding of 4',6-diamidino-2-phenylindole (DAPI) to double-stranded GC polymers either in the alternating or in homopolymer sequence was investigated using fluorescence techniques. We employed fluctuation correlation spectroscopy, which measures the diffusion coefficient of fluorescent particles, to demonstrate that the fluorescence was originating from relatively slowly diffusing entities. These entities display a very large heterogeneity of diffusing coefficients, indicating that molecular aggregation is extensive in our samples. We used frequency domain fluorometry to characterize the fluorescence lifetime of the species, while varying the GC polymer-dye coverage systematically. At very low coverage we observed a relatively bright fluorescent component with a lifetime value of approximately 4 ns. The stoichiometry of binding of this bright species was such that it can only arise from rare molecular structures, either unusual loops or large molecular aggregates. The amount and characteristics of this bright fluorescent component were different between the homo and the alternating polymer, indicating that the difference in sequence of the two polymers is responsible for the different aggregates which are then detected in the fluorescence experiment. At large GC polymer coverage we observed a relatively wide distribution of fluorescent species with short lifetime values, in the range between 0.12 and 0.2 ns. Given the stoichiometry of binding of this fluorescent component, we concluded that it could arise either from intercalative and/or non-specific binding to the DNA double-stranded molecules. We comment on the origin of the rare but brightly fluorescent binding sites and discuss the potential to detect such unusual DNA structures.

Binding Sites↗

PubMed2001

Highly efficient expression of rabbit neutrophil peptide-1 gene in Chlorella ellipsoidea cells.

A highly efficient system was developed for the expression of foreign genes in Chlorella ellipsoidea cells. The effect of five promoters on the expression efficiency of beta-glucuronidase (GUS) gene was evaluated by transient expression of the UidA gene. Among these promoters, Ubiquitin-omega was found to be the most efficient and was selected to drive the expression of foreign genes in Chlorella cells. A gene encoding the mature rabbit neutrophil peptide-1 (NP-1) was introduced into the cells. Integration of the gene for NP-1 into the Chlorella genome was confirmed by PCR and Southern blot analysis. In, vitro anti-microbial testes demonstrated the expression of biologically active NP-1 by the transgenic Chlorella cells.

Animals↗

PubMed2001

The Aalpha6 locus: its relation to mating-type regulation of sexual development in Schizophyllum commune.

We have isolated and examined the Aalpha6 mating-type locus of Schizophyllum commune as a first step toward resolving a functional difference between this locus and the Aalpha loci previously studied. Our analyses show Aalpha6 to be remarkably similar to the Aalpha loci of known structure. The locus is composed of two, divergently transcribed genes similar in size to known Z and Y genes of the Aalpha loci. We have termed the two genes, Z6 and Y6, on the basis of their demonstrated mating activities and encoded protein motifs. The Z6 gene encodes a homeodomain-related sequence, two acidic regions and a predicted coiled-coil motif. The Y6 gene encodes a homeodomain, predicted coiled-coil motif, two regions with homology to the Abeta locus gene V6, a basic region encoding a putative nuclear localization sequence and a serine-rich region. The Z6 and Y6 proteins share these features with the other known Z and Y proteins, respectively. One of the two amino acid sequences with homology to the AbetaV6 protein has not previously been reported.

Amino Acid Sequence↗

PubMed2001

Functional expression of angiotensin II receptors in type-I cells of the rat carotid body.

Angiotensin II increases afferent discharge from the carotid body in vitro. We hypothesized that angiotensin II receptors (AT receptors) are expressed functionally in the type-I cell of the carotid body. Cytosolic free [Ca2+] ([Ca2+]i) in type-I cells freshly dissociated from rat carotid bodies was measured spectrofluorimetrically. Angiotensin II (10-100 nM) concentration-dependently increased [Ca2+]i in type-I cells. The [Ca2+]i response was blocked by pretreatment with losartan (1 microM), an AT1 receptor antagonist, but not by blockade of AT2 receptors with PD- 123319 (1 microM). Moreover, the gene expression of AT1 receptors was assessed by the reverse transcriptase polymerase chain reaction and gene transcripts of both AT1a and AT1b receptors were detected in the carotid body. In addition, immunohistochemical study revealed that AT1 immunoreactivity was localized in lobules of type-I cells in the carotid body. Taken together, these results suggest that type-I cells in the rat carotid body express functional angiotensin II receptors. The binding of angiotensin II to the AT1 receptors increases [Ca2+]i, a key step of the intracellular signalling cascade following the activation of the receptors. It is concluded that angiotensin II modulates carotid body chemoreceptor function directly via AT1 receptors in the type-I cell.

Angiotensin II↗

PubMed2001

Orthopedic applications of gene therapy.

A literature review of the applications of gene therapy for the treatment of orthopedic disorders was conducted, and showed that gene therapy provides us with new possibilities for the clinical management of orthopedic disorders. Most of these disorders, such as failure to obtain spinal fusion, disc degeneration, fracture and segmental bone defects, bone tumor, articular disorders, soft-tissue injury, genetic disorders, and nerve and muscular disorders, are difficult to treat by traditional surgical or medical means, and are under investigation for gene therapy. Many rapid advances have been made in the field of this novel approach. Although a number of obstacles remain to be solved before gene therapy can be applied for clinical use in humans, it is already apparent that gene therapy has the great potential of becoming a valuable clinical treatment for orthopedic disorders in the twenty-first century. With the development of gene transfer techniques, gene therapy will probably have numerous applications in orthopedic disorders.

Animals↗

PubMed2001

Molecular heterogeneity of O-acetylserine sulfhydrylase by two-photon excited fluorescence fluctuation spectroscopy.

O-acetylserine sulfhydrylase, a homo-dimeric enzyme from Salmonella typhimurium, covalently binds one pyridoxal 5'-phosphate molecule per subunit as a fluorescent coenzyme. Different tautomers of the Schiff base between the coenzyme and lysine 41 generate structured absorption and fluorescence spectra upon one-photon excitation. We investigated the protein population heterogeneity by fluorescence correlation spectroscopy and lifetime techniques upon two-photon excitation. We sampled the fluorescence intensity from a small number of molecules (approximately 10) and analyzed the distribution of photon counts to separately determine the number and the fluorescence brightness of excited protein molecules. The changes in the average number of molecules and in the fluorescence brightness with the excitation wavelength indicate the presence of at least two fluorescent species, with two-photon excitation maxima at 660 and 800 nm. These species have been identified as the enolimine and ketoenamine tautomers of the protein-coenzyme internal aldimine. Their relative abundance is estimated to be 4:1, whereas the ratio of their two-photon cross sections is reversed with respect to the single-photon excitation case. Consistent results are obtained from the measurement of the lifetime decays, which are sensitive to the excited-state heterogeneity. At least two components were detected, with lifetimes of approximately 2.5 and 0.5 ns. The lifetimes are very close to the values measured in bulk solutions upon one-photon excitation and attributed to the ketoenamine tautomer and to a dipolar species formed upon proton dissociation in the excited state.

Biochemistry↗

PubMed2001

Theoretical kinetic studies of models for binding myosin subfragment-1 to regulated actin: Hill model versus Geeves model.

It was previously shown that a one-dimensional Ising model could successfully simulate the equilibrium binding of myosin S1 to regulated actin filaments (T. L. Hill, E. Eisenberg and L. Greene, Proc. Natl. Acad. Sci. U.S.A. 77:3186-3190, 1980). However, the time course of myosin S1 binding to regulated actin was thought to be incompatible with this model, and a three-state model was subsequently developed (D. F. McKillop and M. A. Geeves, Biophys. J. 65:693-701, 1993). A quantitative analysis of the predicted time course of myosin S1 binding to regulated actin, however, was never done for either model. Here we present the procedure for the theoretical evaluation of the time course of myosin S1 binding for both models and then show that 1) the Hill model can predict the "lag" in the binding of myosin S1 to regulated actin that is observed in the absence of Ca++ when S1 is in excess of actin, and 2) both models generate very similar families of binding curves when [S1]/[actin] is varied. This result shows that, just based on the equilibrium and pre-steady-state kinetic binding data alone, it is not possible to differentiate between the two models. Thus, the model of Hill et al. cannot be ruled out on the basis of existing pre-steady-state and equilibrium binding data. Physical mechanisms underlying the generation of the lag in the Hill model are discussed.

Actins↗

PubMed2001

Regulation of endothelin-1 synthesis in human pulmonary arterial smooth muscle cells. Effects of transforming growth factor-beta and hypoxia.

OBJECTIVE: Endothelin-1 (ET-1) potently regulates pulmonary vascular tone and promotes vascular smooth muscle cell growth. Clinical and animal studies implicate increased ET-1 production in the pathogenesis of primary and secondary pulmonary hypertension. Although pulmonary arterial smooth muscle cells (PASMCs) synthesize ET-1 under basal conditions, it is unknown whether factors that may be important in pulmonary hypertension, such as transforming growth factor-beta (TGF-beta) or hypoxia, augment ET-1 production by these cells. METHODS: We determined the effect of TGF-beta and hypoxia on ET-1 release and preproET-1 mRNA from cultured rat and human PASMCs. RESULTS: In the basal state, rat and human PASMCs synthesize, on average (mean+/-S.E.M.), 872+/-114 and 563+/-57 pg ET-1/mg cell protein over 24 h, respectively, a level that causes autocrine and paracrine effects in other tissues. TGF-beta significantly increases the expression of preproET-1 mRNA and ET-1 production by both rat and human PASMCs. Hypoxia for 24 h, however, does not affect ET-1 release from rat or human PASMCs. CONCLUSIONS: Cultured rat and human PASMCs are a source of ET-1 production. Enhanced ET-1 release from PASMCs may contribute to the pathophysiology of TGF-beta-induced pulmonary hypertension. ET-1 production by PASMCs is unlikely to contribute to the role of ET-1 in hypoxia-induced pulmonary vasoconstriction.

Animals↗

PubMed2001

Increased extravascular forces limit endothelium-dependent and -independent coronary vasodilation in congestive heart failure.

OBJECTIVE: The increase in coronary blood flow (CBF) in response to endothelium-dependent vasodilators is reduced in congestive heart failure (CHF) suggesting endothelial dysfunction. However, increases in extravascular compressive forces secondary to elevated left ventricular diastolic pressure (LVEDP) in CHF might contribute to this abnormality. METHODS: We measured CBF responses to intracoronary doses of the endothelium-dependent vasodilators acetylcholine (ACH) and bradykinin (BK) and the endothelium-independent vasodilator sodium nitroprusside (SNP) in the same eight dogs before (control) and after CHF was produced by 23+/-3 days of rapid ventricular pacing. In five of the dogs with CHF the zero-flow pressure (P(zf)), which reflects extravascular compressive forces in the maximally vasodilated coronary circulation (adenosine) was measured and found to strongly correlate with LVEDP (r=0.91). Coronary vascular resistance (CVR) at each concentration of vasodilator before and after the development of CHF was corrected for estimated coronary back pressure: CVR=(P(Ao)-LVEDP)/CBF, where P(Ao) is mean aortic pressure. RESULTS: CHF resulted in a significant decrease in CBF and increase in heart rate and LVEDP compared to control (P<0.05). The CBF responses to ACH, BK and SNP were all significantly reduced in the failing hearts (P<0.01). However, after correction for the elevated LVEDP in CHF, the response of CVR to the endothelium-dependent vasodilators was not different from normal. CONCLUSION: These findings suggest that endothelium mediated vasodilation is preserved in CHF, but that increased extravascular compressive forces act to limit the increase in CBF.

Acetylcholine↗

PubMed2001

Motion rivalry impairs motion repulsion.

In their classic study on motion repulsion, Marshak and Sekuler (Science 205 (1979) 1399) reported a repulsion of up to 10 degrees when two different directions of motion were presented dichoptically. However, subjects in that study did not experience binocular rivalry, presumably because of the brief presentation time. In the present study, we measured repulsion during binocular rivalry by requiring subjects to dichoptically view the stimuli until one direction of motion appeared to exclusively dominate the other (Blake, Yu, Lokey, & Norman (1998). J. Cogn. Neurosci., 10, 46-60). We found that motion repulsion was significantly reduced during exclusive dominance. Indeed, after controlling for reference repulsion--the misjudgment of a single direction of motion (Rauber & Treue (1998). Perception, 27, 393-402)--we found no significant motion repulsion during exclusive dominance. These data suggest that motion repulsion may require the perception, rather than merely the physical presence, of multiple directions.

Humans↗

PubMed2001

Effect of acid and surfactant treatment on activated sludge dewatering and settling.

The effect of pretreating activated sludge with sulfuric acid and surfactant on its exocellular polymer(ECP), dewaterability and settleability was investigated. It was observed that the centrifugal dewatering efficiency was increased with the decrease of sludge pH value, and which was further improved if the surfactant was simultaneously applied. However, to the filtration dewatering, the water content reached the minimum in the case of pH 2.5, and the additional use of surfactant was also favorable. The water content of sludge dewatered with filtration reached 73.99% when a pH 2.5 and a 0.1 g surfactant were employed, which was reduced by around 2% as compared with surfactant unused. Experimental results indicated that the sludge sedimentation rate was significantly accelerated under pH 2.5 condition, and which was increased once more by the utilization of surfactant. Further studies revealed that treating activated sludge with sulfuric acid at pH 2.5 or combined with surfactant was an effective method to remove the polymers from sludge surface and induced the decrease of ECP, which resulted in the improvement of dewaterability and settleability. This study suggested the potentiality of improving activated sludge mechanical dewaterability by the use of sulfuric acid to control its pH at 2.5 or together with a surfactant.

Acids↗

PubMed2001

Effects of redox potential and pH value on the release of rare earth elements from soil.

Equilibrium release experiments were conducted under three different pH values of 3.5, 5.5 and 7.5 as well as three redox potentials of 400, 0 and -100 Mv to investigate the influence of redox potential and pH value on the La, Ce, Gd and Y release of from the simulated-REEs-accumulation (SRA) soil. Oxygen and nitrogen were allowed to flow into soil suspension to adjust redox potential to a preset value, and 1 mol/l HCl or 1 mol/l NaOH solutions were added into the soil suspension to keep pH at a preset value. Results indicated that La, Ce, Gd and Y release increased gradually with the decrease of pH value or Eh, and the influence of redox potential on Ce was more remarkable than on La, Gd and Y. At the same time. It was observed that La, Ce, Gd and Y releases were positively correlated with the release of Fe and Mn, indicating that La, Ce, Gd and Y releases might originate from dissolution of Fe-Mn oxyhydroxides under reduction and low pH conditions. Moreover, it was found that alteration of pH value and redox potential might affect the change of La, Ce, Gd and Y species in the soil. The contents of La, Ce, Gd and Y in exchangeable fraction and Fe-Mn oxide fraction in the solid phase from soil suspension separation decreased with the decline of pH value and redox potential. Multiple stepwise regression analysis showed that exchangeable fraction and Fe-Mn oxide fraction predominately contributed to the La, Ce, Gd and Y release. Low pH value and redox potential were more favorable to La, Ce, Gd and Y releases following the change of their species. The La, Ce, Gd and Y contents in exchangeable fraction and Fe-Mn oxide fraction are the main contributors to their release.

Biological Availability↗

PubMed2001

Bladder stone incidence in persons with spinal cord injury: determinants and trends, 1973-1996.

OBJECTIVES: To examine the current trend in the incidence of an initial bladder stone and the potential contributing factors among persons with spinal cord injury. METHODS: A longitudinal cohort of 1336 patients with spinal cord injury who were injured between 1973 and 1996 and followed up on a yearly basis up to 1999 in a single institution was used to estimate bladder stone incidence. Multivariable analysis was performed to identify risk factors for an initial bladder stone. RESULTS: During the study period, 229 incident bladder stone cases were documented. It is estimated that for those injured in 1973 to 1979, 1980 to 1984, 1985 to 1989, and 1990 to 1996, the 5-year cumulative incidence rate of an initial bladder stone was 29%, 23%, 14%, and 8%, respectively (P <0.0001). This decreasing trend was consistent for various demographic and clinical characteristics. During the first year after injury only, the bladder stone risk increased with decreasing age (P <0.0001) and was greater for whites. A neurologically complete lesion was associated with an increased bladder stone risk in later years (P = 0.008). Males and persons with indwelling and intermittent catheters had a higher risk during all the years after the injury. CONCLUSIONS: With improvement in urologic rehabilitation, bladder stone incidence has declined during the past several decades. The study results, however, suggest that new strategic interventions may be required to further prevent stone occurrence in individuals with spinal cord injury and a complete neurologic lesion who are using indwelling catheterization, because these patients are still at a relatively higher risk.

Adolescent↗