Biomedical subjects

Neeraja Kambham

Publications and source records attributed to Neeraja Kambham.

13 recordsLinked to original sources

PubMed2006

Connective tissue growth factor-specific monoclonal antibody therapy inhibits pancreatic tumor growth and metastasis.

Pancreatic cancer is highly aggressive and refractory to most existing therapies. Past studies have shown that connective tissue growth factor (CTGF) expression is elevated in human pancreatic adenocarcinomas and some pancreatic cancer cell lines. To address whether and how CTGF influences tumor growth, we generated pancreatic tumor cell lines that overexpress different levels of human CTGF. The effect of CTGF overexpression on cell proliferation was measured in vitro in monolayer culture, suspension culture, or soft agar, and in vivo in tumor xenografts. Although there was no effect of CTGF expression on proliferation in two-dimensional cultures, anchorage-independent growth (AIG) was enhanced. The capacity of CTGF to enhance AIG in vitro was linked to enhanced pancreatic tumor growth in vivo when these cells were implanted s.c. in nude mice. Administration of a neutralizing CTGF-specific monoclonal antibody, FG-3019, had no effect on monolayer cell proliferation, but blocked AIG in soft agar. Consistent with this observation, anti-CTGF treatment of mice bearing established CTGF-expressing tumors abrogated CTGF-dependent tumor growth and inhibited lymph node metastases without any toxicity observed in normal tissue. Together, these studies implicate CTGF as a new target in pancreatic cancer and suggest that inhibition of CTGF with a human monoclonal antibody may control primary and metastatic tumor growth.

Animals↗

PubMed2006

Evaluation of C4d staining in liver and small intestine allografts.

CONTEXT: Antibody-mediated humoral rejection in kidney and heart allografts is well recognized and is often associated with poor outcome. C4d deposition in allograft biopsy specimens occurs at sites of antibody-mediated complement activation and has become one of the histopathologic criteria for diagnosis of humoral rejection in the kidney and the heart. OBJECTIVE: To study immunohistochemical C4d staining as a potential diagnostic marker in liver and small intestine allograft biopsy specimens. DESIGN: Thirty-six small intestine and 71 liver specimens, including native specimens, allografts with and without histologic features of acute cellular rejection, and explants, were stained with antisera to C4d using an immunohistochemical method on formalin-fixed, paraffin-embedded tissue. RESULTS: In small intestine, C4d labeled capillaries in 27% of cases with no evidence of rejection, 36% of cases with evidence of acute rejection, and 2 (28%) of 7 specimens of native normal small intestine. In liver allograft biopsy specimens, C4d stained endothelium of veins, arteries, and/or sinusoids in 2 (8%) of 25 cases of acute rejection with central vein involvement; C4d staining was negative in biopsy specimens with no evidence of rejection. C4d stained the endothelium in a subset of explanted liver allografts with ductopenic rejection or chronic vascular rejection and strongly stained 1 explant with features of hyperacute rejection. CONCLUSIONS: The clinical utility of C4d staining in solid organ transplantation may vary by organ. Our data show C4d is unlikely to have utility in small intestine allograft biopsy specimens; however, further study in liver allografts, in conjunction with donor-specific antibody testing, is warranted.

Acute Disease↗

PubMed2005

Utility of syndecan-1 (CD138) expression in the diagnosis of undifferentiated malignant neoplasms: a tissue microarray study of 1,754 cases.

Syndecan-1, a heparan sulfate-rich membrane glycoprotein, is expressed in plasma cells and is considered a reliable marker of plasmacytic differentiation. However, it has not been widely tested in non-hematolymphoid tissues, and thus its utility in the setting of an undifferentiated malignant neoplasm has not been evaluated. The authors conducted an extensive study of CD138 staining in over 1,700 normal, benign, and malignant non-hematolymphoid tissues, using five tissue microarrays. Immunohistochemical staining was performed with two commercially available CD138 monoclonal antibodies directed against syndecan-1 (Serotec, Oxford, UK, and DAKO, Carpenteria, CA). In addition to the specific membrane staining, many normal tissues and epithelial tumors showed strong cytoplasmic immunoreactivity. A small subset of mesenchymal neoplasms also showed membrane and cytoplasmic immunoreactivity. In squamous cell carcinoma of the head and neck, renal cell carcinoma, and prostate adenocarcinoma, the intensity of CD138 staining inversely correlated with the histologic grade of the carcinoma. However, statistically significant staining differences and their correlation with histologic grades differed depending on whether the Serotec or the DAKO antibody was used. These results indicate that CD138 immunoreactivity is widespread in normal and neoplastic epithelial tissues, as well as a variety of undifferentiated epithelial and mesenchymal processes. The authors conclude that the expression of syndecan-1, although relatively specific to plasma cells within the hematolymphoid system, should be interpreted with extreme caution in the setting of an undifferentiated neoplasm. Furthermore, the two commercially available monoclonal CD138 antibodies tested in this study showed significant differences in their immunoreactivity in different tumor types.

Adult↗

PubMed2005

Multinucleated epithelial giant cells in colorectal polyps: a potential mimic of viropathic and/or dysplastic changes.

Multinucleated epithelial giant cells (MEG) simulating viral cytopathic effect and/or dysplasia have been reported in the esophagus in association with inflammation, but the occurrence of similar cells in the colon has not been documented. Twenty-three colon specimens (22 biopsies and 1 partial colectomy) featuring MEG from 21 patients were evaluated for a variety of histologic features and correlated with clinical, endoscopic, and follow-up data. Patients included 9 males and 12 females (mean age, 64.9 years; range, 45-86 years). Eleven cases were obtained from 10 asymptomatic patients undergoing surveillance biopsies. Presenting symptoms in the remaining patients were dyspepsia, anemia, abdominal pain, and hematochezia. Over half (13 of 23) of the specimens were from descending and rectosigmoid colon, and almost all were visualized as polyps on endoscopy. Microscopically, all but 1 of the cases featured multiple MEG (range, 6 to >50 cells per biopsy) in the base and mid crypt zones of inflamed polyps with serrated architecture. Immunohistochemical stains for CMV, HSV, adenovirus, EBV, and polyoma virus were negative and no viral particles were identified on ultrastructural examination. Nuclear staining for hMLH1 and hMSH2, markers of microsatellite instability, was similar in distribution to adjacent serrated crypts, but reduced staining intensity was noted in occasional multinucleated cells. Expression of Ki-67 and cleaved caspase 3 was consistent with a quiescent or low proliferative state. Clinical follow-up was available for 9 patients (mean duration, 22.7 months). One patient died of heart failure; all others were well at last follow-up. Bizarre MEG may occasionally be seen within the crypts of inflamed polyps with serrated architecture, raising concern for dysplasia or viral infection. Immunohistochemical and ultrastructural studies fail to establish a viral etiology, and follow-up does not indicate clinically aggressive disease. These changes appear to represent a nonspecific, possibly degenerative response to inflammation and injury, and should be distinguished from dysplasia.

Aged↗

PubMed2005

Gastrointestinal leukocytoclastic vasculitis: an adverse effect of sirolimus.

An 18-yr-old Hispanic female with end-stage renal disease secondary to chronic glomerulonephritis of unknown etiology underwent cadaveric renal transplantation. She was placed on a steroid-free protocol with tacrolimus and mycophenolate mofetil (MMF) for maintenance immunosuppression. Approximately 8 months post-transplantation, MMF was replaced by sirolimus (SRL) because of persistent leukopenia. Four months after the initiation of SRL, the patient began to experience chronic, constant periumbilical abdominal pain in the absence of vomiting, diarrhea or melena. Esophagogastroduodenoscopy and CT scans revealed significant diffuse mucosal thickening of the antrum, duodenum, and jejunum; leukocytoclastic vasculitis was identified on antral biopsy. A repeat biopsy after reduction of sirolimus dose by 50% over 6 months showed mild chronic inflammation of stomach and duodenum with some improvement in abdominal pain. Discontinuation of SRL and replacement with low dose MMF resulted in complete resolution of pain and normalization of gastrointestinal anatomy by imaging studies within 2 months. In light of this report, drug-induced leukocytoclastic vasculitis caused by SRL should be considered in the differential diagnosis of chronic abdominal pain in a patient with organ transplantation.

Abdominal Pain↗

PubMed2004

Cytomegalovirus infection in steroid-refractory ulcerative colitis: a case-control study.

Cytomegalovirus (CMV) infection is reported to be a cause of steroid-refractory ulcerative colitis (UC), but the strength of this association has not been tested in a case control study. Controlled studies have also not been performed to determine the sensitivity of available immunohistochemical techniques to detect CMV in this setting. The pathology database at Stanford Hospital was searched for UC patients with a diagnosis of "severe colitis" between the years 1992 and 2002 and medical records were reviewed. Forty patients were identified with refractory UC, defined as poor response to highdose systemic steroids for >2 weeks. Another group of 40 patients with severe, but nonrefractory, UC was case-matched for age and year of biopsy. A series of 40 patients who underwent colectomy for reasons other than inflammatory bowel disease with representative sections of "normal" colon were selected as noncolitis controls. CMV inclusions were detected on hematoxylin and eosin (H&E) in 2 of 40 patients with refractory UC, but not in other patients. Immunohistochemistry (IHC) detected CMV in 10 of 40 (25%) patients with refractory UC and 1 of 40 (2.5%) patients with nonrefractory UC (P = 0.007). The CMV-positive cases initially identified on IHC but not on H&E were re-reviewed for viral inclusions on H&E: 3 had rare, but typical, inclusions; 3 had atypical inclusions; and 3 had no inclusions. CMV was not detected by H&E or IHC in 40 noncolitis controls. Of 10 steroid-refractory UC patients with CMV detected, 7 were refractory to cyclosporin or 6-mercaptopurine/azathioprine (70%) and 6 had undergone proctocolectomy (60%) prior to detection of the CMV. Two patients with recognized CMV infection were treated with gancyclovir, improved, and were able to taper off steroids and avoid proctocolectomy. This study provides evidence that unrecognized and therefore untreated CMV infection is significantly associated with steroid-refractory UC. Moreover, IHC is more sensitive than H&E for detection of CMV and should be considered as part of the routine evaluation of steroid-refractory UC patients, before proceeding with other medical or surgical therapy that may be unnecessary once the CMV is treated.

Adolescent↗

PubMed2003

Gene expression in the normal adult human kidney assessed by complementary DNA microarray.

The kidney is a highly specialized organ with a complex, stereotyped architecture and a great diversity of functions and cell types. Because the microscopic organization of the nephron, the functional unit of the kidney, has a consistent relationship to the macroscopic anatomy of the kidney, knowledge of the characteristic patterns of gene expression in different compartments of the kidney could provide insight into the functions and functional organization of the normal nephron. We studied gene expression in dissected renal lobes of five adult human kidneys using cDNA microarrays representing approximately 30,000 different human genes. Total RNA was isolated from sections of the inner and outer cortex, inner and outer medulla, papillary tips, and renal pelvis and from glomeruli isolated by sieving. The results revealed unique and highly distinctive patterns of gene expression for glomeruli, cortex, medulla, papillary tips, and pelvic samples. Immunohistochemical staining using selected antisera confirmed differential expression of several cognate proteins and provided histological localization of expression within the nephron. The distinctive patterns of gene expression in discrete portions of the kidney may serve as a resource for further understanding of renal physiology and the molecular and cellular organization of the nephron.

Adult↗

PubMed2003

Molecular heterogeneity in acute renal allograft rejection identified by DNA microarray profiling.

BACKGROUND: The causes and clinical course of acute rejection vary, and it is not possible to predict graft outcome reliably on the basis of available clinical, pathological, and genetic markers. We hypothesized that previously unrecognized molecular heterogeneity might underlie some of the variability in the clinical course of acute renal allograft rejection and in its response to treatment. METHODS: We used DNA microarrays in a systematic study of gene-expression patterns in biopsy samples from normal and dysfunctional renal allografts. A combination of exploratory and supervised bioinformatic methods was used to analyze these profiles. RESULTS: We found consistent differences among the gene-expression patterns associated with acute rejection, nephrotoxic effects of drugs, chronic allograft nephropathy, and normal kidneys. The gene-expression patterns associated with acute rejection suggested at least three possible distinct subtypes of acute rejection that, although indistinguishable by light microscopy, were marked by differences in immune activation and cellular proliferation. Since the gene-expression patterns pointed to substantial variation in the composition of immune infiltrates, we used immunohistochemical staining to define these subtypes further. This analysis revealed a striking association between dense CD20+ B-cell infiltrates and both clinical glucocorticoid resistance (P=0.01) and graft loss (P<0.001). CONCLUSIONS: Systematic analysis of gene-expression patterns provides a window on the biology and pathogenesis of renal allograft rejection. Biopsy samples from patients with acute rejection that are indistinguishable on conventional histologic analysis reveal extensive differences in gene expression, which are associated with differences in immunologic and cellular features and clinical course. The presence of dense clusters of B cells in a biopsy sample was strongly associated with severe graft rejection, suggesting a pivotal role of infiltrating B cells in acute rejection.

Acute Disease↗

PubMed2003

Endoscopic selective neck dissection in a porcine model.

OBJECTIVE: To investigate the feasibility of accomplishing a selective neck dissection (SND) endoscopically. STUDY DESIGN: Prospective, nonrandomized experimental investigation in a porcine model. METHODS: Unilateral endoscopic SNDs were performed in Yorkshire pigs. A spacious operative pocket was developed using a combination of hernia balloon expansion followed by low-pressure (4 mm Hg) carbon dioxide insufflation. The sternomastoid muscle, thymus, submandibular gland, lymph nodes, and fibrofatty tissue were removed in a procedure approximating a human SND. Data (operative time, blood loss, arterial blood gas values, weight of the specimen, and complications) were prospectively recorded. The specimens were analyzed by a pathologist, and the number and size of lymph nodes were recorded. RESULTS: Fourteen endoscopic SNDs were successfully performed. No conversions to open surgery were necessary. The median operative time was 131 minutes (range, 95-235 minutes). The median estimated blood loss was 4 mL (range, 0-150 mL). The mean +/- SD specimen weight was 42.9 +/- 8.3 g; the mean number +/- SD of nodes retrieved from the neck specimen was 4.8 +/- 2.2, and the mean +/- SD maximal nodal dimension was 2.4 +/- 0.5 cm. The arterial PCO2 increased by an average of only 3.9 mm Hg from the beginning to the end of the surgery; correspondingly, the pH fell by only 0.02. There were no major complications, and no animals had to be euthanized prior to the completion of the procedure. CONCLUSIONS: Endoscopic neck dissection in a porcine model can be accomplished with a combination of strategies to overcome the dilemma of creating and maintaining an operative pocket. The merger of SND with endoscopic technology offers the promise of truly minimally invasive surgery for the node-negative neck.

Anesthesia↗

PubMed2003

A randomized, placebo-controlled trial of IGF-1 for delayed graft function: a human model to study postischemic ARF.

BACKGROUND: Insulin-like growth factor (IGF-1) has been shown in animal models to accelerate recovery from acute renal failure (ARF). However, a therapeutic trial of recombinant human (rh) IGF-1 in patients with ARF in the intensive care unit (ICU) failed to demonstrate efficacy [1]. Such patients often had multiple organ failure, recurrent renal injury, and a delay of several days before commencing treatment. METHODS: To circumvent these confounding factors, we randomized recipients of cadaveric renal allografts to immediate (<5 hours) rhIGF-1 versus placebo therapy (100 mg/kg subcutaneously twice a day for 6 days). Preliminary observations 3 hours posttransplantation in an additional 44 patients revealed a creatinine clearance < or = 20 mL/min to predict protracted ARF. Thus, this value was used to determine study eligibility. RESULTS: Creatinine clearance prior to commencing treatment was not significantly different between the two groups (8 +/- 5 mL/min for IGF-1 and 7 +/- 6 mL/min for placebo; P = 0.39). Inulin clearance on day 7, the primary outcome measure, was 21 +/- 22 mL/min and 19 +/- 19 mL/min in the IGF-1 (N = 19) and placebo (N = 24) groups, respectively (P = 0.67). Secondary outcome measures, including nadir serum creatinines after 6 weeks and need for dialysis, also did not differ between the two groups. We performed an analysis of statistical power using the placebo arm of the trial. Defining a twofold increase above placebo in day 7 glomerular filtration rate (GFR) as of meaningful biologic significance, we determined that the modest sample size used in the present study is adequate. CONCLUSION: We, thus, conclude that (1) IGF-1 treatment is unlikely to benefit ARF and (2) the transplanted kidney is a good model to screen new agents for ARF that have demonstrated promise in animal trials.

Acute Kidney Injury↗

PubMed2003

Surgical robotic applications in otolaryngology.

OBJECTIVES: To explore the feasibility of performing endo-robotic neck surgery in a porcine model and to compare the results of robotically enhanced endoscopic surgery with those from a conventional endoscopic technique. STUDY DESIGN: Prospective, nonrandomized experimental investigation in a porcine model. METHODS: We performed a consecutive series of endoscopic neck surgeries using the daVinci surgical system (Intuitive Surgical Inc.). The length of time required to establish the operative pocket and to assemble the robotic components, as well as the total duration of each operation, was recorded. The animals were continuously monitored for heart rate, blood pressure, and end-tidal CO(2) pressure, and evaluation for presence of pneumothorax and subcutaneous emphysema was undertaken postoperatively. The specimens were examined histologically. RESULTS: Four different types of neck surgery were successfully performed on both sides of the neck of four animals using the daVinci surgical system. Creation of the operative pocket took, on average (+/-SD), 18.1 +/- 11.9 minutes, and assembly of the robot required 12.5 +/- 9.9 minutes, resulting in a mean preparation time for all procedures of 30.6 +/- 21.0 minutes. The mean operative time for submandibular resection (n = 3) was 19.0 +/- 6.6 minutes, with a total procedure time of 39.0 +/- 10.2 minutes. Selective neck dissections (n = 3) required a mean operative time of 66.0 +/- 18.5 minutes and a total procedure time of 85.7 +/- 16.7 minutes. One partial parotidectomy and one thymectomy were also performed. The median estimated blood loss was 0 mL (range, 0-10 mL). The end-tidal CO(2) pressure fell from the start to the end of the procedures by a mean of 4.4 +/- 7.9 mm Hg. The blood pressure fell by a mean of 1.9 +/- 7.5 mm Hg. There was one case of modest subcutaneous emphysema, and there were no cases of pneumothorax or air embolism. No conversions to open resection were necessary. CONCLUSIONS: Robotically enhanced endoscopic surgery in the neck is feasible and offers a number of compelling advantages over conventional endoscopic neck surgery. Clinical trials will be necessary to determine whether these advantages can be achieved in clinical practice.

Animals↗

PubMed2001

Renal monoclonal immunoglobulin deposition disease: the disease spectrum.

This study reports the clinicopathologic findings and outcome in 34 patients with renal monoclonal immunoglobulin deposition disease (MIDD), which included 23 light-chain DD (LCDD), 5 light- and heavy-chain DD (LHCDD), and 6 heavy-chain DD (HCDD). A total of 23 patients had pure MIDD, whereas 11 patients had LCDD with coexistent myeloma cast nephropathy (LCDD & MCN). Renal biopsy diagnosis preceded clinical evidence of dysproteinemia in 68% of all cases. By immunofluorescence, the composition of deposits included 11kappa/1lambda (LCDD), 3IgGkappa/2IgGlambda (LHCDD), 5gamma/1alpha (HCDD), and 10kappa/1lambda (LCDD & MCN). Patients with pure MIDD presented with mean serum creatinine of 4.2 mg/dl, nephrotic proteinuria, and hypertension. Cases of HCDD were associated with a CH1 deletion and frequently had hypocomplementemia and a positive hepatitis C virus antibody but negative hepatitis C virus PCR. LCDD & MCN is a morphologically and clinically distinct entity from pure MIDD, presenting with higher creatinine (mean, 7.8 mg/dl; P = 0.01), greater dialysis dependence (64 versus 26%; P = 0.053), subnephrotic proteinuria, and less nodular glomerulopathy (18 versus 100%; P < 0.0001). Multiple myeloma was more frequently diagnosed in LCDD & MCN than in pure MIDD (91 versus 31%; P = 0.025). Renal and patient survivals were significantly worse in patients with LCDD & MCN (mean, 4 and 22 mo, respectively), compared with patients with pure MIDD (mean, 22 and 54 mo). Chemotherapy stabilized or improved renal function in 10 of 15 patients (67%) with pure MIDD who presented with creatinine of <5.0 mg/dl, emphasizing the importance of early detection. On multivariate analysis, initial creatinine was the only predictor of renal and patient survival in pure MIDD, underscoring the prognostic significance of the renal involvement.

Aged↗

PubMed2000

Lithium nephrotoxicity: a progressive combined glomerular and tubulointerstitial nephropathy.

This study examines the clinical features, pathologic findings, and outcome of 24 patients with biopsy-proven lithium toxicity. The patient population was 50% male, 87.5% Caucasian, and had a mean age of 42.5 yr (range, 26 to 57). Mean duration of lithium therapy for bipolar disorder was 13.6 yr (range, 2 to 25). All patients were biopsied for renal insufficiency (mean serum creatinine 2.8 mg/dl; range, 1.3 to 8.0), with associated proteinuria >1.0 g/d in 41.7%. Nephrotic proteinuria (>3.0 g/d) was present in 25%. Other features included nephrogenic diabetes insipidus in 87% and hypertension in 33.3%. Renal biopsy revealed a chronic tubulointerstitial nephropathy in 100%, with associated cortical and medullary tubular cysts (62.5%) or dilatation (33.3%). All of the renal cysts stained for epithelial membrane antigen, while 51.4% stained with lectin Arachis hypogaea, and only 3.8% stained with Tetragonolobus purpureas, indicating they originated from distal and collecting tubules. The degree of tubular atrophy and interstitial fibrosis was graded as severe in 58.3%, moderate in 37.5%, and mild in 4.2% of cases. There was a surprisingly high prevalence of focal segmental glomerulosclerosis (50%) and global glomerulosclerosis (100%), sometimes of equivalent severity to the chronic tubulointerstitial disease. The significant degree of foot process effacement (mean 34%, five of 14 cases with >50%) suggests a potential direct glomerular toxicity. Focal segmental glomerulosclerosis correlated with proteinuria >1.0 g/d (P = 0.0014, Fisher exact test). Despite discontinuation of lithium, seven of nine patients with initial serum creatinine values >2.5 mg/dl progressed to end-stage renal disease (ESRD). Only three patients, all with initial serum creatinine <2.1 mg/dl, had subsequent improvement in renal function. By Kaplan-Meier survival analysis, the only significant predictor of progression to ESRD was serum creatinine >2.5 mg/dl at biopsy (P = 0. 008). In conclusion, lithium nephrotoxicity primarily targets distal and collecting tubules, with a higher incidence of proteinuria and associated glomerular pathology than recognized previously. Renal dysfunction is often irreversible despite lithium withdrawal, and early detection is essential to prevent progression to ESRD.

Adult↗