Biomedical subjects

Rajen Ramsamooj

Publications and source records attributed to Rajen Ramsamooj.

7 recordsLinked to original sources

PubMed2006

Delivery of antioxidative enzyme genes protects against ischemia/reperfusion-induced liver injury in mice.

Hepatic ischemia/reperfusion (I/R) injury is characterized by the generation of reactive oxygen species (ROS), such as superoxide anions and hydrogen peroxide. The aim of this study is to investigate whether antioxidative gene delivery by our polylipid nanoparticles (PLNP) is an effective approach for prevention of the injury. Polyplexes of extracellular superoxide dismutase (EC-SOD) and/or catalase genes were injected via the portal vein 1 day prior to a warm I/R procedure in mice. The effects of the gene delivery were determined 6 hours after starting reperfusion. PLNP-mediated antioxidative gene delivery led to a marked increase in human EC-SOD and catalase gene expression in the liver. Liver superoxide dismutase (SOD) and catalase activity both increased approximately 10-fold. Increased liver superoxide anion levels caused by the I/R procedure were reduced to normal levels by EC-SOD gene delivery. The overexpression of these 2 antioxidative genes significantly suppressed the I/R-induced elevation of serum alanine aminotransferase (ALT) levels, decreased liver malondialdehyde content, restored glutathione reserve, and improved liver histology. In conclusion, EC-SOD or catalase gene delivery by PLNP resulted in high levels of the transgene activity in the liver, and markedly attenuated hepatic I/R injury. The protection is directly associated with elevated antioxidative enzyme activity as the result of the gene delivery. This novel approach may become a potential therapy to improve graft function and survival after liver transplantation.

Animals↗

PubMed2004

Acute renal transplant injury and interaction between antithymocyte globulin and pooled human immunoglobulin.

The increasing number of highly sensitized patients awaiting renal transplantation has prompted the use of induction immunosuppression regimens including pooled human intravenous immunoglobulin (IVIG) combined with polyclonal anti-lymphocyte sera. We report a case of a patient who received a live donor transplant after abrogation of donor-specific positive cytotoxic crossmatch by IVIG. She developed early acute tubular injury associated with IVIG, mannitol, and hypertonic saline infusion. Furthermore, a possible interaction between IVIG and rabbit antithymocyte globulin (ATG) occurred, suggested by an increased number of peripheral CD3(+) lymphocytes after initial rapid lymphodepletion. We suggest that IVIG-associated nephrotoxicity should be considered in the differential diagnosis of early allograft dysfunction, and furthermore, that IVIG may interact with polyclonal antilymphocyte serum to affect the amount of lymphodepletion achieved.

Antilymphocyte Serum↗

PubMed2002

Real-time, high-definition, three-dimensional microscopy for evaluating problematic cervical Papanicolaou smears classified as atypical squamous cells of undetermined significance.

BACKGROUND: The perceived inadequacies of the cervical Papanicolaou (Pap) smear have been attributed to sampling, screening, or interpretive errors. Within this type of cytologic preparation, there are thick cell clusters in which the cells are obscured. It may not possible to evaluate these areas by conventional microscopy. The authors clinically tested the hypothesis that high-definition, three-dimensional (3-D) microscopy based on multiple oblique illumination (MOI), with its ability to penetrate into thick areas, would be useful in evaluating problematic cervical Pap smears, particularly those diagnosed as atypical squamous cells of undetermined significance (ASCUS). METHODS: ASCUS Pap smears and corresponding surgical biopsy specimens were evaluated prospectively using standard, axially illuminated microscopes and a new high-definition, 3-D microscope employing MOI. The Pap smears were reviewed in a blinded fashion with both types of microscopy. The rendered diagnoses were then compared with the subsequent tissue biopsies, which also were blinded, as the definitive end point. RESULTS: It was immediately apparent that the high-definition, 3-D MOI microscope had better resolution compared with the standard microscopes. Pap smears and biopsy diagnoses were correlated significantly for MOI (P < 0.001), and there were significant improvements (P = 0.0108) in accuracy when 3-D, high-definition microscopy was compared with conventional microscopy. The authors found no statistically significant correlation between ASCUS diagnoses that were rendered by using standard microscopes compared with the subsequent biopsy. CONCLUSIONS: Due to enhanced visualization through thick cell clusters, an increased depth of field, light penetration, and resolution, high-definition, 3-D microscopy based on MOI produced superior accuracy compared with conventional light microscopy in evaluating cervical Pap smears.

Adolescent↗

PubMed2002

Mechanisms of alloimmune tolerance associated with mixed chimerism induced by vascularized bone marrow transplants.

Rat limb allograft recipients represent surgically induced, immediately vascularized bone marrow transplant (VBMT) chimeras. The majority of these chimeras undergo tolerance while a minority develop graft versus host disease (GVHD). T-cell chimerism and associated mechanisms of cellular immune nonresponsiveness were investigated in tolerant VBMT chimeras. A strong correlation (p < 0.01) was observed between the clinical onset of GVHD and levels of donor T-cell chimerism approximating or greater than 50%. However, stable mixed chimerism was associated with tolerance. In conclusion, three major sequential mechanisms of immune nonresponsiveness were elucidated in tolerant VBMT chimeras over time and included development of nonspecific suppressor cells (which potentially represent natural suppressor cells), maturation of antigen-specific suppressor cell circuits, and eventually putative clonal inactivation.

Animals↗

PubMedDate not supplied

Evaluation of the clinical and histologic features of renal allograft rejection in cats.

OBJECTIVES: To describe the clinical signs and histopathologic features of renal allograft rejection in cats, and to provide a historical, untreated control group for use in future studies of feline renal allograft rejection. ANIMALS: Fourteen adult research cats. METHODS: Renal transplantation and bilateral nephrectomy were performed in pairs of immunogenically mismatched cats. A physical examination was performed, and packed cell volume, total protein, and plasma creatinine concentrations were measured each day after surgery. The cats were euthanatized when plasma creatinine concentration exceeded 7 mg/dL or when weight loss exceeded 20%. Renal histopathology was scored according to the Banff 97 criteria by 3 pathologists. RESULTS: Nine cats completed the study. Plasma creatinine exceeded 7 mg/dL in 5 cats, weight loss exceeded 20% in 3 cats, and 1 cat was found dead. Clinical signs in cats with rejection were nonspecific or absent. Rectal temperature decreased by 0.8 +/- 0.5 degrees C in the 24 hours before euthanasia. The pathologists agreed on the allograft histopathologic category in 6 of 9 cats. The histologic consensus was acute/active rejection in 8 cats and normal in 1 cat. Median survival time of the 8 cats with histologically confirmed allograft rejection was 23 days (range, 8-34 days). CONCLUSIONS AND CLINICAL RELEVANCE: Renal allograft rejection is associated with minimal clinical signs. Therefore, plasma creatinine concentration should be measured routinely in patients with a functioning allograft. An increase in plasma creatinine concentration is highly suspicious for allograft rejection, although a biopsy of the renal allograft is needed for definitive diagnosis.

Animals↗

PubMedDate not supplied

Near-infrared autofluorescence imaging for detection of cancer.

Near-infrared autofluorescence imaging of tissues under long-wavelength laser excitation in the green and red spectral region complemented by cross-polarized elastic light scattering was explored for cancer detection. Various types of normal and malignant human tissue samples were utilized in this investigation. A set of images for each tissue sample was recorded that consisted of two autofluorescence images obtained under 532- and 632.8-nm excitation and light-scattering images obtained under linearly polarized illumination at 700, 850, and 1000 nm. These images were compared with the histopathology of the tissue sample. The experimental results indicated that for various tissue types, the intensity of the autofluorescence integrated over the 700 to 1000-nm spectral region was considerably different in cancer tissues than in that of the contiguous non-neoplastic tissues. This difference provided the basis for the detection of cancer and delineation of the tumor margins. Variations on the relative intensity were observed among different tissue types and excitation wavelengths.

Humans↗

PubMedDate not supplied

Spectroscopic detection of bladder cancer using near-infrared imaging techniques.

High-contrast imaging of bladder cancer is demonstrated using near-infrared autofluorescence under long-wavelength laser excitation in combination with cross-polarized elastic light scattering. Fresh unprocessed surgical specimens obtained following cystectomy or transurethral resection were utilized and a set of images for each tissue sample was recorded. These images were compared with the histopathology of the tissue sample. The experimental results indicate that the intensity of the near-infrared emission as well as that of the cross-polarized backscattered light was considerably different in cancer tissues than in that of the contiguous nonneoplastic tissues, allowing an accurate delineation of a tumor's margins.

Feasibility Studies↗