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Biomedical subjects

Ajay K Singh

Publications and source records attributed to Ajay K Singh.

At least 19 recordsLinked to original sources
PubMed2006

Correction of anemia with epoetin alfa in chronic kidney disease.

BACKGROUND: Anemia, a common complication of chronic kidney disease, usually develops as a consequence of erythropoietin deficiency. Recombinant human erythropoietin (epoetin alfa) is indicated for the correction of anemia associated with this condition. However, the optimal level of hemoglobin correction is not defined. METHODS: In this open-label trial, we studied 1432 patients with chronic kidney disease, 715 of whom were randomly assigned to receive a dose of epoetin alfa targeted to achieve a hemoglobin level of 13.5 g per deciliter and 717 of whom were assigned to receive a dose targeted to achieve a level of 11.3 g per deciliter. The median study duration was 16 months. The primary end point was a composite of death, myocardial infarction, hospitalization for congestive heart failure (without renal replacement therapy), and stroke. RESULTS: A total of 222 composite events occurred: 125 events in the high-hemoglobin group, as compared with 97 events in the low-hemoglobin group (hazard ratio, 1.34; 95% confidence interval, 1.03 to 1.74; P=0.03). There were 65 deaths (29.3%), 101 hospitalizations for congestive heart failure (45.5%), 25 myocardial infarctions (11.3%), and 23 strokes (10.4%). Seven patients (3.2%) were hospitalized for congestive heart failure and myocardial infarction combined, and one patient (0.5%) died after having a stroke. Improvements in the quality of life were similar in the two groups. More patients in the high-hemoglobin group had at least one serious adverse event. CONCLUSIONS: The use of a target hemoglobin level of 13.5 g per deciliter (as compared with 11.3 g per deciliter) was associated with increased risk and no incremental improvement in the quality of life. (ClinicalTrials.gov number, NCT00211120 [ClinicalTrials.gov].).

Aged↗
PubMed2006

Outcomes of renal transplantation for recipients with lupus nephritis: analysis of the Organ Procurement and Transplantation Network database.

Prior analyses of transplant outcomes in lupus transplant recipients have not consisted of multivariate analyses in the modern immunosuppressive era. Here, we compared patient and graft outcomes in lupus and non-lupus recipients transplanted between 1996 to 2000 using the United Network of Organ Sharing/Organ Procurement Transplant Network database. We evaluated the impact of recipient and donor demographic factors, time on dialysis and the initial immunosuppression regimen on rejection rates and transplant outcomes. Univariate analysis showed similar graft but better patient survival rates for primary lupus and non-lupus transplant recipients (5-year patient survival rates for lupus cohort 85.2% for deceased donor transplants and 92.1% for living donor transplants as opposed to 82.1% and 89.8% respectively for the non-lupus cohort; P=0.05 and 0.03) but similar patient survival rates for deceased donor retransplant patients. After controlling for confounding factors, no differences in patient or graft survival were seen between the two groups. No difference in acute rejection rates were observed in deceased donor transplants, but there was a small but significant increase in the risk of acute rejection in living donor lupus transplant recipients (hazard ratio=1.19, P=0.05). Risk of graft failure was lower for deceased donor recipients receiving MMF (five-year graft loss rate=29.6% for MMF vs. 40.2% for those not receiving MMF, P<0.0001), but no differences were seen among living donor recipients. Outcomes were similar regardless of type of calcineurin inhibitor, induction therapy, and time on dialysis. We conclude that lupus transplant recipients have outcomes generally equivalent to non-lupus transplant recipients.

Adult↗
PubMed2006

Imaging-guided catheter drainage of abdominal collections with fistulous pancreaticobiliary communication.

OBJECTIVE: Our aim was to study the success of percutaneous imaging-guided catheter drainage of abdominal collections with documented fistulous pancreaticobiliary communication. MATERIALS AND METHODS: Fifty-seven patients (age range, 23-88 years) with abdominal collections who underwent imaging-guided catheter drainage were included in this retrospective study. These collections showed communication with either the pancreatic duct (n = 15) or the biliary duct (n = 42) on imaging. The imaging guidance included CT (n = 40), sonography (n = 17), and fluoroscopy (n = 4), either alone or in combination. The success of catheter drainage was described as resolution of the collection on follow-up imaging and clinical improvement. Other treatments directed toward management of leaks or collections were also recorded. RESULTS: The success rates of catheter drainage for abdominal collections with biliary and pancreatic ductal communication were 93% (39/42) and 67% (10/15), respectively. The difference was statistically significant (p = 0.01). The three complications seen in this study were pneumothorax in one patient, bowel perforation in one, and death in one. The drainage catheter was upsized in five patients and an additional catheter was needed in nine patients. CONCLUSION: Imaging-guided catheter drainage is a clinically useful option for drainage of abdominal collections that have pancreaticobiliary communications. The success rate is significantly better for collections with biliary communication than for those with pancreatic communication.

Adult↗
PubMed2005

Ultrafast intermolecular hydrogen bond dynamics in the excited state of fluorenone.

Steady-state fluorescence and time-resolved absorption measurements in pico- and femtosecond time domain have been used to investigate the dynamics of hydrogen bond in the excited singlet (S(1)) state of fluorenone in alcoholic solvents. A comparison of the features of the steady-state fluorescence spectra of fluorenone in various kinds of media demonstrates that two spectroscopically distinct forms of fluorenone in the S(1) state, namely the non-hydrogen-bonded (or free) molecule as well as the hydrogen-bonded complex, are responsible for the dual-fluorescence behavior of fluorenone in solutions of normal alcoholic solvents at room temperature (298 K). However, in 2,2,2-trifluoroethanol (TFE), a strong hydrogen bond donating solvent, emission from only the hydrogen-bonded complex is observed. Significant differences have also been observed in the temporal evolution of the absorption spectroscopic properties of the S(1) state of fluorenone in protic and aprotic solvents following photoexcitation using 400 nm laser pulses. An ultrafast component representing the solvent-induced vibrational energy relaxation (VER) process has been associated with the dynamics of the S(1) state of fluorenone in all kinds of solvents. However, in protic solvents, in addition to the VER process, further evolution of the spectroscopic and dynamical properties of the S(1) state have been observed because of repositioning of the hydrogen bonds around the carbonyl group. In normal alcohols, two different kinds of hydrogen-bonded complex of the fluorenone-alcohol system with different orientations of the hydrogen bond with respect to the carbonyl group and the molecular plane of fluorenone have been predicted. On the other hand, in TFE, formation of only one kind of hydrogen-bonded complex has been observed. These observations have been supported by theoretical calculations of the geometries of the hydrogen-bonded complexes in the ground and the excited states of fluorenone. Linear correlation between the lifetimes of the equilibration process occurring because of repositioning of the hydrogen bonds and Debye or longitudinal relaxation times of the normal alcoholic solvents establish the fact that, in weakly hydrogen bond donating solvents, the hydrogen bond dynamics can be described as merely a solvation process. Whereas, in TFE, hydrogen bond dynamics is better described by a process of conversion between two distinct excited states, namely, the non-hydrogen-bonded form and the hydrogen-bonded complex.

Journal Article↗
PubMed2005

Regeneration of plants from alginate-encapsulated shoot tips of Withania somnifera (L.) Dunal, a medicinally important plant species.

A protocol was developed for plant regeneration from encapsulated shoot tips collected from in vitro proliferated shoots of Withania somnifera. The best gel composition was achieved using 3% sodium alginate and 75 mM CaCl2.2H2O. The maximum percentage response (87%) for conversion of encapsulated shoot tips into plantlets was achieved on MS medium supplemented with 0.5 mg/l IBA after 5 weeks of culture. The conversion of encapsulated shoot tips into plantlets also occurred when calcium alginate beads having entrapped propagules were directly sown in autoclaved soilrite moistened with 14-MS salts.

Alginates↗
PubMed2005

Ultrafast intermolecular electron transfer dynamics: Perylene in electron-accepting micellar medium.

The dynamics of ultrafast photoinduced intermolecular electron transfer (ET) from the excited singlet (S1) state of perylene (Pe) to an electron-accepting cationic surfactant molecule, N-cetylpyridinium chloride (CPC), in aqueous micellar solutions has been investigated using the femtosecond transient absorption spectroscopic technique with temporal resolution of 120 fs. The Pe molecule is localized at or near the micellar surface, where it coexists with the pyridinium moieties (headgroups of the micelle) of the surfactant molecule. Following photoexcitation of Pe, an electron is transferred to the neat and geometrically restricted headgroup of the micelle. Dynamics of the forward ET process as well as the geminate recombination or back ET (BET) process have been followed by monitoring the temporal evolution of the S1 state of Pe and the cation radical of Pe (Pe*+), respectively. The multiexponential forward ET process indicates that the ET dynamics is highly correlated with the spatial distributions of the micellar headgroups around a donor Pe molecule and thus dependent on the donor-acceptor distance. The distance-dependent ET and BET rates have been calculated following the method of Weidemaier and Fayer (J. Chem. Phys. 1995, 102, 3820) to get the best fit parameters for the multiexponetial temporal profiles for the S1 state of Pe as well as Pe*+. Because the acceptor is a constituent of the neat micellar medium, their confinement on the surface of the microheterogeneous medium provides a very large concentration such that, even though the forward transfer rate is 0.06 ps(-1) at the distance of closest approach, the ET process is complete within a 200-ps time domain. If the concepts of distribution of ET distances are utilized, the possible role of material diffusion on the kinetics of forward ET is ruled out. This is an experimental study to show, for the first time, the ultrafast distance-dependent light-induced ET dynamics following both the excited state of the donor and the cation radical formed in an ET process using the transient absorption spectroscopic technique in a self-reactive restrictive environment.

Electrons↗
PubMed2005

Acute epiploic appendagitis in hernia sac: CT appearance.

We describe an unusual cause of acute abdomen due to acute epiploicappendagitis located within an incisional hernia sac. The contrast-enhanced CT showed an oval fat density structure with surrounding inflammation in the transverse mesocolon. The contrast-enhanced CT findings of the inflammation of appendices epiploicae of the transverse colon were diagnostic in this case.

Abdomen, Acute↗
PubMed2005

Rationale--Trial to Reduce Cardiovascular Events with Aranesp Therapy (TREAT): evolving the management of cardiovascular risk in patients with chronic kidney disease.

BACKGROUND: Patients with chronic kidney disease (CKD) have a high burden of mortality and cardiovascular morbidity. Additional strategies to modulate cardiovascular risk in this population are needed. Data suggest that anemia is a potent and potentially modifiable risk factor for cardiovascular disease in patients with CKD, but these data remain unsubstantiated by any randomized controlled trial (RCT). Furthermore, the clinical practice guidelines for anemia management in patients with CKD are based on limited data. The need for new RCTs to address critical knowledge deficits, particularly with regard to the impact of anemia therapy on cardiovascular disease and survival, is recognized within the guidelines and independent comprehensive reviews of the existing published trial data. STUDY DESIGN: The Trial to Reduce Cardiovascular Events with Aranesp (Amgen Inc, Thousand Oaks, Calif) (darbepoetin alfa) Therapy (TREAT) is a 4000-patient, multicenter, double-blind RCT, designed to determine the impact of anemia therapy with darbepoetin alfa on mortality and nonfatal cardiovascular events in patients with CKD and type 2 diabetes mellitus. Subjects will be randomized in a 1:1 manner to either darbepoetin alfa therapy to a target hemoglobin (Hb) of 13 g/dL or control, consisting of placebo for Hb > or =9 g/dL or darbepoetin alfa for Hb <9 g/dL until Hb is again Hb > or =9 g/dL. TREAT is event-driven and has a composite primary end point comprising time to mortality and nonfatal cardiovascular events, including myocardial infarction, myocardial ischemia, stroke, and heart failure. TREAT will provide data that are critical to evolution of the management of cardiovascular risk in this high-risk population.

Anemia↗
PubMed2005

Complications of chronic kidney disease: anemia, mineral metabolism, and cardiovascular disease.

This article focuses on the importance of three major complications of chronic kidney disease: (1) anemia, (2) calcium-phosphorus regulation and bone disease, and (3) cardiovascular risk profiling and treatment. The arguments for early and effective intervention have been amply made with respect to these three complications. Substantive trial data are sorely need to provide the definitive evidence that effective treatment of these complications results in better outcomes.

Anemia↗
PubMed2005

The role of kidney biopsy in the management of lupus nephritis.

PURPOSE OF REVIEW: This review evaluates the role of kidney biopsy as a tool in the diagnosis, prognostication and therapeutic management of lupus nephritis. The renal biopsy is the only method available for diagnosing and classifying lupus nephritis. However, disagreements persist regarding the appropriate role of a renal biopsy in the management and identification of predictors of short and long-term outcomes. RECENT FINDINGS: Recent modifications to the classification of lupus nephritis, the emergence of newer scoring indices, and the availability of a variety of therapeutic options predicate a reassessment of the role of the renal biopsy in the management of lupus nephritis, especially for high-risk patients. SUMMARY: Despite some controversy, the renal biopsy has been shown to provide information over and above that provided by the clinical variables, and remains a pivotal element in optimizing therapy and the rational management of lupus nephritis.

Biopsy, Needle↗
PubMed2005

Uncertainty in the treatment of anemia in chronic kidney disease.

The practice of medicine requires that the assimilation of today's best available data be directed toward individual patient-care decisions. In the absence of definitive data, surrogate measures are adopted to anticipate how therapeutic strategies would influence clinical outcomes and prognosis. Unfortunately, randomized controlled clinical trials (RCTs) have not always found these estimates of outcome to be reliable. Anemia is a clear marker of adverse prognosis, which can be modified by erythropoietic stimulating proteins (ESP). At present, there is sufficient uncertainty regarding the risks and benefits of ESP treatment in patients with chronic kidney disease and anemia to warrant major RCTs. This article reviews the rationale and design features for these trials.

Anemia↗
PubMed2004

Cholecystocolonic fistula: serial CT imaging features.

We report the CT imaging findings of an unusual case of cholecystocolonic fistula, which had presented in the emergency department with melena. It is rare for the fistulous communication to occur between gallbladder and the colon. We describe the serial imaging findings, which were diagnostic of this condition.

Aged↗
PubMed2004

Strategies for preservation of ovarian and testicular function after immunosuppression.

Gonadal toxicity as a side effect of cyclophosphamide therapy is a common long-term problem in the treatment of a variety of glomerular diseases. In both men and women treated with cyclophosphamide, the consequences of infertility can have great physical and emotional consequences; thus, this issue often has a critical role in the decision to decline treatment with cyclophosphamide. There exists a critical need for strategies for preservation of fertility in both men and women who require treatment with cyclophosphamide. This review explores emerging therapeutic options in this arena, which include sperm and oocyte cryopreservation, medical treatments such as testosterone therapy for men and gonadotropin-releasing hormone agonist therapy for both men and women, and, finally, the relatively new strategy of germ-cell transplantation for both ovarian and testicular tissue, which still remains in the experimental stages.

Cell Transplantation↗
PubMed2004

New subcategories of class IV lupus nephritis: are there clinical, histologic, and outcome differences?

BACKGROUND: The International Society of Nephrologists and Renal Pathology Society (ISN/RPS) classification of lupus nephritis proposes a controversial subclassification of class IV lupus nephritis into IV-segmental (IV-S) and IV-global (IV-G). METHODS: A retrospective analysis of a biopsy-proven cohort of patients with lupus nephritis using the ISN/RPS classification was performed. RESULTS: The prevalence of class IV was 47% in the cohort of 70 patients with lupus nephritis. Of 33 patients with class IV lupus nephritis, 11 patients had class IV-S and 22 patients had class IV-G. There were no significant differences in age, sex, and ethnicity in the 2 groups. Greater serological activity (lower C4 level) was observed in the IV-S group, whereas serum creatinine levels and diastolic blood pressures were significantly greater in the IV-G group. Hematocrit levels, significant proteinuria (urine protein > or =3 + ), duration of systemic lupus erythematosus, and the Systemic Lupus Erythematosus Disease Activity Index were similar in the 2 groups. Histologically, combined lesions with segmental endocapillary proliferation and fibrinoid necrosis were significantly more frequent in the IV-S group. The percentage of glomeruli with cellular crescents also was greater in the IV-S group, but the difference was not significant. Wire loops were more common in the IV-G group. Transformation to IV-G was observed in 2 of 3 specimens from repeated biopsies available in the IV-S group; greater than 50% of the IV-G group had both segmental and global glomerular involvement. No significant difference was detected in outcomes in the 2 groups after average follow-ups of 38 and 55 months in the IV-S and IV-G groups, respectively. CONCLUSION: A clinical and prognostic distinction between IV-S and IV-G remains to be proven.

Adolescent↗
PubMed2004

Pancreatoduodenectomy: imaging and image-guided interventional treatment.

Though the mortality of pancreatoduodenectomy (Whipple surgery) is under 4%, the morbidity continues to be high. The interventional radiologist plays an important role in the management of postoperative complications, such as abdominal abscess, bilomas, liver abscess, biliary obstruction, pseudocyst, and hemorrhage. Identification of the normal postoperative anatomy is crucial to correctly interpreting CT scans for short-term complications and long-term tumor recurrence.

Humans↗
PubMed2004

Imaging of inflammatory bowel disease: CT and MR.

Cross-sectional imaging has come to play a central role in the imaging of the abdomen. Concurrent to this, the role of CT and MRI in the imaging of inflammatory bowel disease has also increased in importance. These modalities offer numerous advantages over more traditional methods of radiologic diagnosis, and provide essential information not only for initial diagnosis, but for management, follow-up and detection of potential complications. On the horizon are several derivative techniques involving CT and MRI, potentially in combination with PET imaging; these may further improve the specificity and sensitivity of imaging modalities for diagnosis of inflammatory bowel disease.

Adolescent↗