Ivan Cheng
Stanford University
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American Journal of Physiology-gastrointestinal and Liver Physiology | 1998
Naibedya Chattopadhyay; Ivan Cheng; Kimberly V. Rogers; Daniela Riccardi; Amy E. Hall; Ruben Diaz; Steven C. Hebert; David I. Soybel; Edward M. Brown
The extracellular calcium (Ca2+o)-sensing receptor (CaR) plays vital roles in Ca2+o homeostasis, but no data are available on its expression in small and large intestine. Polymerase chain reaction products amplified from reverse-transcribed duodenal RNA using CaR-specific primers showed > 99% homology with the rat kidney CaR. Northern analysis with a CaR-specific cRNA probe demonstrated 4.1- and 7.5-kb transcripts in all intestinal segments. Immunohistochemistry with CaR-specific antisera showed clear basal staining of epithelial cells of small intestinal villi and crypts and modest apical staining of the former, whereas there was both basal and apical staining of colonic crypt epithelial cells. In situ hybridization and immunohistochemistry also demonstrated CaR expression in Auerbachs myenteric plexus of small and large intestines and in the submucosa in the region of Meissners plexus. Our results reveal CaR expression in several cell types of small and large intestine, in which it may modulate absorptive and/or secretomotor functions.The extracellular calcium ([Formula: see text])-sensing receptor (CaR) plays vital roles in [Formula: see text] homeostasis, but no data are available on its expression in small and large intestine. Polymerase chain reaction products amplified from reverse-transcribed duodenal RNA using CaR-specific primers showed >99% homology with the rat kidney CaR. Northern analysis with a CaR-specific cRNA probe demonstrated 4.1- and 7.5-kb transcripts in all intestinal segments. Immunohistochemistry with CaR-specific antisera showed clear basal staining of epithelial cells of small intestinal villi and crypts and modest apical staining of the former, whereas there was both basal and apical staining of colonic crypt epithelial cells. In situ hybridization and immunohistochemistry also demonstrated CaR expression in Auerbachs myenteric plexus of small and large intestines and in the submucosa in the region of Meissners plexus. Our results reveal CaR expression in several cell types of small and large intestine, in which it may modulate absorptive and/or secretomotor functions.
Spine | 2008
Eugene J. Carragee; Eric L. Hurwitz; Ivan Cheng; Linda J. Carroll; Margareta Nordin; Jaime Guzman; Paul M. Peloso; Lena W. Holm; Pierre Côté; Sheilah Hogg-Johnson; Gabrielle van der Velde; J. David Cassidy; Scott Haldeman
Study Design. Best evidence synthesis. Objective. To identify, critically appraise, and synthesize literature from 1980 through 2006 on surgical interventions for neck pain alone or with radicular pain in the absence of serious pathologic disease. Summary of Background Data. There have been no comprehensive systematic literature or evidence-based reviews published on this topic. Methods. We systematically searched Medline for literature published from 1980 to 2006 on percutaneous and open surgical interventions for neck pain. Publications on the topic were also solicited from experts in the field. Consensus decisions were made about the scientific merit of each article; those judged to have adequate internal validity were included in our Best Evidence Synthesis. Results. Of the 31,878 articles screened, 1203 studies were relevant to the Neck Pain Task Force mandate and of these, 31 regarding treatment by surgery or injections were accepted as scientifically admissible. Radiofrequency neurotomy, cervical facet injections, cervical fusion and cervical arthroplasty for neck pain without radiculopathy are not supported by current evidence. We found there is support for short-term symptomatic improvement of radicular symptoms with epidural corticosteroids. It is not clear from the evidence that long-term outcomes are improved with the surgical treatment of cervical radiculopathy compared to nonoperative measures. However, relatively rapid and substantial symptomatic relief after surgical treatment seems to be reliably achieved. It is not evident that one open surgical technique is clearly superior to others for radiculopathy. Cervical foramenal or epidural injections are associated with relatively frequent minor adverse events (5%–20%); however, serious adverse events are very uncommon (<1%). After open surgical procedures on the cervical spine, potentially serious acute complications are seen in approximately 4% of patients. Conclusion. Surgical treatment and limited injection procedures for cervical radicular symptoms may be reasonably considered in patients with severe impairments. Percutaneous and open surgical treatment for neck pain alone, without radicular symptoms or clear serious pathology, seems to lack scientific support.
Gastroenterology | 1999
Ivan Cheng; Imtiaz Qureshi; Naibedya Chattopadhyay; Athar Qureshi; Robert R. Butters; Amy E. Hall; Robert R. Cima; Kimberly V. Rogers; Steven C. Hebert; John P. Geibel; Edward M. Brown; David I. Soybel
BACKGROUND & AIMS Circulating levels of Ca2+ can influence secretory functions and myoelectrical properties of the stomach. A Ca2+-sensing receptor (CaR) has recently been identified in tissues that regulate systemic Ca2+ homeostasis. The aim of this study was to evaluate expression of CaR in the stomach of the rat. METHODS In forestomach and glandular stomach, reverse-transcription polymerase chain reaction was used to amplify a 380-base pair product, which is 99% homologous with transcripts obtained in parathyroid and kidney. RESULTS Northern analysis of gastric mucosal polyA+ RNA revealed 7. 5- and 4.1-kilobase transcripts, similar to those obtained in rat parathyroid and kidney. Immunohistochemistry revealed CaR expression in regions of the submucosal plexus and myenteric neurons. In sections of intact tissue, preparations of primary culture surface cells and surgically dissected gastric glands, staining was observed consistently in epithelial cells of the gastric glands and in gastric surface cells. In parietal cells in isolated gastric glands, intracellular levels of Ca2+ responded to conditions that are known to activate CaR. CONCLUSIONS These are the first reported observations that CaR is expressed in different epithelial cells of mammalian gastric mucosa and its enteric nerve regions. The effects of extracellular Ca2+ on gastric function may be attributable to activation of CaR.
Spine | 2005
Ivan Cheng; Yongjung Kim; Munish C. Gupta; Keith H. Bridwell; Robert K. Hurford; Stanley S. Lee; Thongchai Theerajunyaporn; Lawrence G. Lenke
Study Design. The results of correction for adolescent idiopathic scoliosis (AIS) were compared using apical sublaminar wires versus pedicle screws. Objective. To compare comprehensively the 2-year minimum postoperative results of posterior correction and spinal fusion using translational correction through either hybrid hook/sublaminar wire/pedicle screw constructs versusin situ rod-contouring correction with pedicle screw constructs in the treatment of AIS at 2 institutions. Summary of Background Data. Despite the reports of satisfactory correction of scoliotic curves by both apical (sublaminar wire) instrumentation and apical pedicle screw instrumentation, to our knowledge, no reports on the comprehensive comparison of hybrid (hook/sublaminar wire/pedicle screw) instrumentation versus segmental pedicle screw instrumentation exist. Methods. A total of 50 patients with AIS at 2 institutions who underwent posterior spinal fusion with sublaminar wire (25 patients) or pedicle screw (25) constructs were sorted and matched according to 4 criteria: (1) similar age at surgery (14.2 years in the sublaminar wire and 14.4 in the pedicle screw group, P = 0.72); (2) similar number of fused vertebrae (11.4 in the sublaminar wire and 11.8 in the pedicle screw group, P = 0.36); (3) similar operative methods; and (4) identical Lenke curve types and similar preoperative major curve measurements (63.5° in the sublaminar wire and 59.5° in the pedicle screw group, P = 0.42). Patients were evaluated preoperatively, immediately postoperatively, and at 2-year follow-up according to radiographic changes in curve correction, operating time, intraoperative blood loss, implant costs, and the Scoliosis Research Society patient questionnaire (SRS-24) scores. Results. After surgery, average major curve correction was 67.4% in the sublaminar wire and 68.1% in the pedicle screw group (P = 0.56). At 2-year follow-up, loss of themajor curve correction was 4.6% in the sublaminar wirecompared to 5.1% in the pedicle screw group (P = 0.79). Postoperative global coronal and sagittal balance were similar in both groups. No significant difference was found in the average number of levels fused from the distal end vertebra (1.48 in the sublaminar wire and 0.64 in the pedicle screw group, P = 0.21). Operating time averaged 350 minutes in the sublaminar wire and 357 in the pedicle screw group (P = 0.86). Intraoperative blood loss was significantly different in both groups (1791 ± 816 mL in the sublaminar wire and 824 ± 440 mL in the pedicle screw group) (P = 0.0003). Average implant cost in the sublaminar wire group (16.0 fixation points; 8341 US dollars) was significantly lower than that of the pedicle screw group (17.1 fixation points; 13,462 US dollars) (P < 0.0001). Postoperative 2-year SRS-24 scores were similar in both groups (sublaminar wire = 107.3, pedicle screw = 103.5, P = 0.19). There were no neurologic or visceral complications related to sublaminar wire or pedicle screw instrumentation and no reoperations at a minimum 2-year follow-up. Conclusions. Apical sublaminar wire and pedicle screw instrumentation both offer similar major curve correction with similar fusion lengths without neurologic problems in the operative treatment of AIS. Although more expensive, pedicle screw constructs had significantly less blood loss and slightly shorter fusion lengths than the sublaminar wire constructs.
Spine | 2005
Scott J. Luhmann; Keith H. Bridwell; Ivan Cheng; Toshihiro Imamura; Lawrence G. Lenke; Mario Schootman
Study Design. Prospective, single-center, nonblinded clinical and radiographic analysis of consecutive adult deformity patients treated with recombinant human bone morphogenetic protein-2 (rhBMP-2) without iliac or rib bone graft supplementation. Objectives. To determine the ability of rhBMP-2 to achieve both anterior and posterior spinal fusion in patients undergoing multilevel fusions for adult spinal deformity. Summary of Background Data. The literature concerning one-level anterior fusions, and potentially one-level posterior fusions, using rhBMP-2 has demonstrated clinical efficacy. No published data exist on the use of rhBMP-2 in multilevel spine fusions. Methods. Prospective analysis of patients treated with rhBMP-2 in multilevel anterior and posterior fusions with a minimum 1-year follow-up. There were a total of 95 patient samples (70 total patients; 25 patients had rhBMP-2 used circumferentially): 46 anterior fusions (Group 1), 41 posterior fusions (Group 2), and 8 patients were “compassionate use” fusions (Group 3). In the anterior fusion group (n = 46), mean rhBMP-2/level was 10.8 mg in titanium mesh cages without any bone graft or other substance. The posterior fusion group had only local bone graft, no harvested rib or iliac bone graft (n = 41). The mean rhBMP-2/level was 13.7 mg. The “compassionate use” group (n = 8 patients) consisted of patients who had prior surgeries, prior iliac harvesting, and substantial comorbidities and therefore a higher concentration and different carrier was used. No local bone graft, no harvested bone was used. The mean rhBMP-2/level was 28.6 mg. The median dose was 40 mg for Group 3. Results. For the anterior fusion group (n = 46), operative levels were deemed fused in 89 of the 93 (96%) levels. For the posterior fusion group (n = 41), a solid fusion was assessed in 110 of the 118 (93%) operative levels. For the “compassionate-use” patients, the overall fusion rate was 100% (52 of 52 operative levels). Conclusions. With the use of rhBMP-2, a high rate of apparent fusion was observed for anterior (96%) and posterior (93%) fusions in adult spinal deformity patients. Use of rhBMP-2 results in a promising early fusion rate without the graft harvest site morbidity.
The Spine Journal | 2011
Bing Wang; Guohua Lü; Alpesh A. Patel; Pei-Gen Ren; Ivan Cheng
BACKGROUND CONTEXT Compared with conventional microsurgical technique, the full endoscopic (FE) interlaminar approach is a more minimally invasive technique for the surgical treatment of lumbar disc herniations. Its efficacy and safety have been confirmed by numerous studies. However, a steep learning curve with the use of such a complex technique is a major concern for the initial adoption of this technique. PURPOSE To evaluate the learning curve of using an FE interlaminar technique for the surgical treatment of lumbar disc herniation. STUDY DESIGN A prospective study of patients with lumbar disc herniation who underwent discectomy via interlaminar approach assisted by FE instruments. PATIENT SAMPLE Thirty patients with lumbar disc herniation underwent discectomy using an interlaminar endoscopic-only approach between 2008 and 2009. METHODS The patients were divided into three groups of 10 sequential cases each. Group A consisted of the first 10 cases, Group B the subsequent 10 cases, and Group C the last 10 cases. The clinical evaluation data included operative time, length of hospital stay, visual analog scale (VAS) leg and back pain scores, complications, and rate of conversion to an open. RESULTS All patients were observed prospectively for 1.61 ± 0.22 years (range, 1.2-2.0 years). There was no measurable intraoperative bleeding and postoperative infections in the three groups. Compared with Group A, the operative time in Group B was significantly decreased (p < .001). The patients in Group C had much less operative time than in Group B (p = .002). There was no significant difference with length of hospital stay in the three groups (p = .897). The improvement of VAS leg and back pain scores in each group was similar: there was a significant improvement (p < .01) at 3 months after surgery when compared with preoperative scores, but there was no statistical difference (p > .05) in the VAS leg and back pain scores between 3 months after surgery and final follow-up. The complication rate was 12.5% for Group A, 10% for Group B, and 0% for Group C. The need for conversion to an open procedure for Group A was 20% compared with zero cases in both Groups B and C. There were no symptomatic recurrences in our study. CONCLUSIONS Excellent clinical and minimally invasive outcomes can be obtained in the surgical treatment of lumbar disc herniation via the interlaminar approach assisted by FE technique. However, attention must be paid to the steep learning curve by using this complex technique. Imprecise anatomic orientation and manipulation inside the spinal canal are key factors in the steep learning curve. Obtaining microsurgical experience, attending workshops, and suitable patient selection can help shorten the learning curve and decrease the complications.
Spine | 2006
Eugene J. Carragee; Todd Alamin; Ivan Cheng; Thomas Franklin; Eric L. Hurwitz
Study Design. Prospective, 5-year, cohort study of working subjects. Objectives. To assess whether the occurrence of common minor trauma events affects the risk of developing serious low back pain (LBP) and LBP disability in subjects with and without degenerative changes to the lumbar spine. Summary of Background Data. Although some theories suggest that minor traumatic events in combination with preexisting degenerative changes commonly cause significant structural injury to spinal segments and serious LBP illness, no prospective data exist on the relationship of minor trauma, detailed structural changes, and outcome measures of serious LBP episodes and occupational disability. Methods. Two hundred subjects without clinical LBP problems were recruited, and underwent baseline clinical and imaging studies. Every 6 months, subjects completed a scripted, algorithm-based interview assessing interval back pain episodes, severity, medical treatment, occupational disability, and the subjects perceived relation of this LBP episode to any preceding event. If a serious LBP episode clinically required a new magnetic resonance examination, the follow-up imaging was obtained and compared to baseline for interval changes. Results. There was no association of minor trauma to adverse LBP events. For each 6-month study interval, the risk of developing a serious LBP episode was 2.1% unassociated with minor trauma and 2.4% following minor trauma (P = 0.59). Neither the frequency of minor trauma events nor the reported severity of the event correlated with adverse outcomes. Subjects with advanced structural findings were not more likely to become symptomatic with minor trauma events than with spontaneously evolving LBP episodes. Follow-up magnetic resonance imaging evaluating new serious LBP illness rarely revealed new clinically significant findings. Age and sex-adjusted prediction models, including abnormal psychometric testing, smoking, and compensation issues, accurately identified 80% of serious LBP events and 93% of LBP disability events. Conclusions. In this study cohort, minor trauma does not appear to increase the risk of serious LBP episodes or disability. The vast majority of incident-adverse LBP events may be predicted not by structural findings or minor trauma but by a small set of demographic and behavioral variables.
Neurosurgery | 2011
Robert T. Arrigo; Paul Kalanithi; Ivan Cheng; Todd Alamin; Eugene J. Carragee; Stefan A. Mindea; Jongsoo Park; Maxwell Boakye
BACKGROUND:Surgery for spinal metastasis is a palliative treatment aimed at improving patient quality of life by alleviating pain and reversing or delaying neurologic dysfunction, but with a mean survival time of less than 1 year and significant complication rates, appropriate patient selection is crucial. OBJECTIVE:To identify the most significant prognostic variables of survival after surgery for spinal metastasis. METHODS:Chart review was performed on 200 surgically treated spinal metastasis patients at Stanford Hospital between 1999 and 2009. Survival analysis was performed and variables entered into a Cox proportional hazards model to determine their significance. RESULTS:Median overall survival was 8.0 months, with a 30-day mortality rate of 3.0% and a 30-day complication rate of 34.0%. A Cox proportional hazards model showed radiosensitivity of the tumor (hazard ratio: 2.557, P < .001), preoperative ambulatory status (hazard ratio: 2.355, P = .0001), and Charlson Comorbidity Index (hazard ratio: 2.955, P < .01) to be significant predictors of survival. Breast cancer had the best prognosis (median survival, 27.1 months), whereas gastrointestinal tumors had the worst (median survival, 2.66 months). CONCLUSION:We identified the Charlson Comorbidity Index score as one of the strongest predictors of survival after surgery for spinal metastasis. We confirmed previous findings that radiosensitivity of the tumor and ambulatory status are significant predictors of survival.
Spine | 2006
Robert K. Hurford; Lawrence G. Lenke; Stanley S. Lee; Ivan Cheng; Brenda A. Sides; Keith H. Bridwell
Study Design. Anterior single or dual-rod instrumentation may be performed for the treatment of main thoracic, thoracolumbar, or lumbar adolescent idiopathic scoliosis (AIS) curves. Objective. To compare the results of anterior dual-rod instrumentation in single-major AIS curves with our previous experience using single-rod constructs. Summary of Background Data. Several reports have described the use of anterior single-rod instrumentation for the treatment of AIS curves with acceptable correction rates but with pseudarthroses/implant failures of up to 31%. Methods. A total of 60 consecutive patients with AIS (12 males and 48 females; average age 15.3 years) with major thoracic (n = 18) or thoracolumbar/lumbar (n = 42) curves were treated with dual-rod instrumented anterior spinal fusion. Follow-up was 2–5 years. Patients were evaluated prospectively with Scoliosis Research Society (SRS) questionnaires. Results. Major thoracic curves were corrected from a mean of 55° to 27° (51% correction), while major thoracolumbar/lumbar curves were corrected from an average of 51° to 17° at latest follow-up (67% correction). No pseudarthroses were identified. With the use of single-rod constructs, a similar amount of coronal correction was obtained for both thoracic (47%) and thoracolumbar/lumbar curves (70%). However, the pseudarthrosis rate for single-rod constructs was 5.5%. The obvious trend toward a lower pseudarthrosis rate in dual-rod (0/60) versus single-rod (5/90) constructs was not statistically significant (P = 0.07). Follow-up SRS questionnaire data for patients with dual-rod instrumentation showed 95% satisfaction, and 93% would choose the same treatment with similar results in the single-rod instrumentation study, 88% patient satisfaction, and 89% choosing the same treatment. Overall SRS scores improved after treatment (P < 0.01). SRS domain scores improved at a significant level for pain (P = 0.05), self-image (P < 0.01), and function (P = 0.01). Conclusion. In this largest, to our knowledge, single-center report of dual-rod constructs for patients with AIS, a similar amount of radiographic deformity correction was obtained when compared to single-rod implants. However, the absence of any pseudarthroses in the 60 patients with dual-rod is a distinct advantage.
American Journal of Physiology-gastrointestinal and Liver Physiology | 1997
Robert R. Cima; Ivan Cheng; Mary E. Klingensmith; Naibedya Chattopadhyay; Olga Kifor; Steven C. Hebert; Edward M. Brown; David I. Soybel
In mammals and amphibians, increases in extracellular Ca2+ can activate bicarbonate secretion and other protective functions of gastric mucosa. We hypothesized that the recently cloned extracellular Ca(2+)-sensing receptor (CaR) is functioning in the gastric mucosa. In Necturus maculosus gastric mucosa, reverse transcription-polymerase chain reaction using primers based on previously cloned CaR sequences amplified a 326-bp DNA fragment that had 84% nucleotide sequence identity with the rat kidney CaR. Immunohistochemical localization of the CaR using specific anti-CaR antiserum revealed its presence on the basal aspect of gastric epithelial cells. In microelectrode studies of Necturus antral mucosa, exposure to elevated Ca2+ (4.8 mM) and the CaR agonists NPS-467 and neomycin sulfate resulted in significant hyperpolarizations of basal membrane electrical potentials and increases in apical-to-basal membrane resistance ratios. Circuit analysis revealed that these changes reflected specific decreases in basolateral membrane resistance. Inhibition of prostaglandin synthesis using indomethacin significantly attenuated these effects. We conclude that the CaR is present and functioning in Necturus gastric antrum.