Clinical Characteristics and Outcomes of Drug-Induced Acute Kidney Injury Cases.

Introduction: Drug-induced acute kidney injury (DI-AKI) is a frequent adverse event. The identification of DI-AKI is challenged by competing etiologies, clinical heterogeneity among patients, and a lack of accurate diagnostic tools. Our research aims to describe the clinical characteristics and predictive variables of DI-AKI. Methods: We analyzed data from the Drug-Induced Renal Injury Consortium (DIRECT) study (NCT02159209), an international, multicenter, observational cohort study of enriched clinically adjudicated DI-AKI cases. Cases met the primary inclusion criteria if the patient was exposed to at least 1 nephrotoxic drug for a minimum of 24 hours prior to AKI onset. Cases were clinically adjudicated, and inter-rater reliability (IRR) was measured using Krippendorff's alpha. Variables associated with DI-AKI were identified using L1 regularized multivariable logistic regression. Model performance was assessed using the area under the receiver operating characteristic curve (ROC AUC). Results: A total of 314 AKI cases met the eligibility criteria for this analysis, and 271 (86%) cases were adjudicated as DI-AKI. The majority of the AKI cases were recruited from the United States (68%). The most frequent causal nephrotoxic drugs were vancomycin (48.7%), nonsteroidal antiinflammatory drugs (18.2%), and piperacillin/tazobactam (17.8%). The IRR for DI-AKI adjudication was 0.309. The multivariable model identified age, vascular capacity, hyperglycemia, infections, pyuria, serum creatinine (SCr) trends, and contrast media as significant predictors of DI-AKI with good performance (ROC AUC 0.86). Conclusion: The identification of DI-AKI is challenging even with comprehensive adjudication by experienced nephrologists. Our analysis identified key clinical characteristics and outcomes of DI-AKI compared to other AKI etiologies.

Cardiovascular and Renal Implications of Myocardial Infarction in the ISCHEMIA-CKD Trial.

BACKGROUND: ISCHEMIA-CKD (International Study of Comparative Health Effectiveness With Medical and Invasive Approaches-Chronic Kidney Disease) reported an initial invasive treatment strategy did not reduce the risk of death or nonfatal myocardial infarction (MI) compared with a conservative treatment strategy in patients with advanced chronic kidney disease, stable coronary disease, and moderate or severe myocardial ischemia. The cumulative frequency of different MI type after randomization and subsequent prognosis have not been reported. METHODS: MI classification was based on the Third Universal Definition for MI. For procedural MI, the primary MI definition used creatine kinase-MB as the preferred biomarker, whereas the secondary MI definition used cTn (cardiac troponin); both definitions included elevated biomarker-only events with higher thresholds than nonprocedural MIs. The cumulative frequency of MI type according to treatment strategy was determined. The association of MI with subsequent all-cause death and new dialysis initiation was assessed by treating MI as a time-dependent covariate. RESULTS: The 3-year incidence of type 1 or 2 MI with the primary MI definition was 11.2% in invasive treatment strategy and 13.6% in conservative treatment strategy (hazard ratio [HR], 0.66 [95% CI, 0.42-1.02]). Procedural MIs were more frequent in invasive treatment strategy and accounted for 9.8% and 28.3% of all MIs with the primary and secondary MI definitions, respectively. Patients had an increased risk of all-cause death after type 1 MI (adjusted HR, 4.35 [95% CI, 2.73-6.93]) and after procedural MI with the primary (adjusted HR, 2.75 [95% CI, 0.99-7.60]) and secondary MI definitions (adjusted HR, 2.91 [95% CI, 1.73-4.88]). Dialysis initiation was increased after a type 1 MI (HR, 6.45 [95% CI, 2.59-16.08]) compared with patients without an MI. CONCLUSIONS: In ISCHEMIA-CKD, the invasive treatment strategy had higher rates of procedural MIs, particularly with the secondary MI definition, and lower rates of type 1 and 2 MIs. Procedural MIs, type 1 MIs, and type 2 MIs were associated with increased risk of subsequent death. Type 1 MI increased the risk of dialysis initiation. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT01985360.

Challenges of Conducting Clinical Trials during the SARS-CoV-2 Pandemic: The ASCEND Global Program Experience.

The coronavirus disease 2019 pandemic has had an unprecedented effect on health and health care and posed challenges to the conduct of clinical trials.Targeted mitigating strategies, on the basis of early and continued data collection from site surveys, limited disruption to the ASCEND trials.Flexibly allowing hemoglobin assessment at local laboratories to inform randomized treatment dosing was key to limiting the discontinuation of treatment.

Urinary Exosomes Identify Inflammatory Pathways in Vancomycin Associated Acute Kidney Injury.

BACKGROUND: Vancomycin is commonly used as a first line therapy for gram positive organisms such as methicillin resistant Staphylococcusaureus. Vancomycin-induced acute kidney injury (V-AKI) has been reported in up to 43% of patients, especially in those with higher targeted trough concentrations. The precise mechanism of injury in humans remains elusive, with recent evidence directed towards proximal tubule cell apoptosis. In this study, we investigated the protein contents of urinary exosomes in patients with V-AKI to further elucidate biomarkers of mechanisms of injury and potential responses. METHODS: Urine samples from patients with V-AKI who were enrolled in the DIRECT study and matched healthy controls from the UAB-UCSD O'Brien Center Biorepository were included in the analysis. Exosomes were extracted using solvent exclusion principle and polyethylene glycol induced precipitation. Protein identity and quantification was determined by label-free liquid chromatography mass spectrometry (LC/MS). The mean peak serum creatinine was 3.7 ± 1.4 mg/dL and time to kidney injury was 4.0 ± 3.0 days. At discharge, 90% of patients demonstrated partial recovery; 33% experienced full recovery by day 28. Proteomic analyses on five V-AKI and 7 control samples revealed 2009 proteins in all samples and 251 proteins significantly associated with V-AKI (Pi-score > 1). The top discriminatory proteins were complement C3, complement C4, galectin-3-binding protein, fibrinogen, alpha-2 macroglobulin, immunoglobulin heavy constant mu and serotransferrin. CONCLUSION: Urinary exosomes reveal up-regulation of inflammatory proteins after nephrotoxic injury in V-AKI. Further studies are necessary in a large patient sample to confirm these findings for elucidation of pathophysiologic mechanisms and validation of potential injury biomarkers.

Eculizumab, a novel potential treatment for acute kidney injury associated with preeclampsia/HELLP syndrome.

The kidney is one of the major organs affected in preeclampsia. There is evidence suggesting a role for excessive complement activation in the pathogenesis of preeclampsia. We describe a case of preeclampsia with severe features, including HELLP syndrome (hemolysis, elevated liver enzymes, low platelets) and acute kidney injury (AKI) that developed following caesarian section. The patient required renal replacement therapy. A trial of daily plasma exchange was not effective. The patient received a single dose of eculizumab, a humanised monoclonal IgG antibody that binds to complement protein C5. One week post administration of eculizumab, there was significant improvement in haematologic, hepatic and renal function. Blood pressure had normalised and renal replacement therapy was discontinued. The use of eculizumab may have contributed to recovery of kidney function further supporting the role of complement activation in the pathogenesis of preeclampsia and associated AKI.

Recurrent case of pregnancy-induced atypical haemolytic uremic syndrome (P-aHUS).

Pregnancy-induced atypical haemolytic uremic syndrome (P-aHUS) is a rare condition characterised by microangiopathic haemolytic anaemia, thrombocytopenia and renal failure. It accounts for approximately 7% of total HUS cases. Here, we present a case of recurrent P-aHUS in a 25-year-old Hispanic woman. Pregnancy was the clear trigger in both instances, and the disease manifested in first week of the postpartum period. Because of her significant obstetric history, a multidisciplinary approach was adopted to monitor her second pregnancy antepartum and post partum. As the patient developed recurrence of P-aHUS 4 days after her delivery, she was immediately administered eculizumab within few hours of disease manifestation. The patient normalised her haematological parameters within 1 week but sustained dialysis-requiring renal failure for a total of 6 weeks. This case highlights the advances as well as the ongoing uncertainties, especially with respect to the use of eculizumab, in this rare but morbid disease.

Management of Acute Kidney Injury in Pregnancy for the Obstetrician.

Acute kidney injury (AKI) is a complex disorder that occurs in several clinical settings. During pregnancy, there are additional unique conditions that contribute to AKI. The clinical manifestations of AKI during pregnancy range from a minimal elevation in serum creatinine to renal failure requiring renal replacement therapy, similar to AKI in the general population. Recent epidemiologic studies in the general population show an increase in mortality associated with AKI, particularly when dialysis is required. The incidence of AKI in pregnancy remains a cause of significant morbidity and mortality.

Promising biomarkers for superimposed pre-eclampsia in pregnant women with established hypertension and chronic kidney disease.

The incidence of pre-eclampsia is high in women with chronic kidney disease and hypertension and the diagnosis is particularly challenging. Bramham et al. (2016) studied various biomarkers with the primary aim of predicting superimposed pre-eclampsia requiring delivery within 14 days of sampling. Their findings of the utility of a single biomarker for diagnosis in this high-risk group is a major advance that has significant implications and holds promise for the future.

Acute Kidney Injury, Recurrent Seizures, and Thrombocytopenia in a Young Patient with Lupus Nephritis: A Diagnostic Dilemma.

Introduction. Posterior reversible encephalopathy syndrome (PRES) is a constellation of clinical and radiologic findings. Fluctuations in blood pressure, seizures, and reversible brain MRI findings mainly in posterior cerebral white matter are the main manifestations. PRES has been associated with multiple conditions such as autoimmune disorders, pregnancy, organ transplant, and thrombotic microangiopathy (TMA). Case Presentation. A 22-year-old woman with history of Systemic Lupus Erythematous complicated with chronic kidney disease secondary to lupus nephritis class IV presented with recurrent seizures and uncontrolled hypertension. She was found to have acute kidney injury and thrombocytopenia. Repeat kidney biopsy showed diffuse endocapillary and extracapillary proliferative and membranous lupus nephritis (ISN-RPS class IV-G+V) and endothelial swelling secondary to severe hypertension but no evidence of TMA. Brain MRI showed reversible left frontal and parietal lesions that resolved after controlling the blood pressure, making PRES the diagnosis. Conclusion. PRES is an important entity that must be recognized and treated early due to the potential reversibility in the early stages. Physicians must have high suspicion for these unusual presentations. We present a case where performing kidney biopsy clinched the diagnosis in our patient with multiple confounding factors.

A Prospective International Multicenter Study of AKI in the Intensive Care Unit.

BACKGROUND AND OBJECTIVES: AKI is frequent and is associated with poor outcomes. There is limited information on the epidemiology of AKI worldwide. This study compared patients with AKI in emerging and developed countries to determine the association of clinical factors and processes of care with outcomes. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This prospective observational study was conducted among intensive care unit patients from nine centers in developed countries and five centers in emerging countries. AKI was defined as an increase in creatinine of ≥0.3 mg/dl within 48 hours. RESULTS: Between 2008 and 2012, 6647 patients were screened, of whom 1275 (19.2%) developed AKI. A total of 745 (58% of those with AKI) agreed to participate and had complete data. Patients in developed countries had more sepsis (52.1% versus 38.0%) and higher Acute Physiology and Chronic Health Evaluation (APACHE) scores (mean±SD, 61.1±27.5 versus 51.1±25.2); those from emerging countries had more CKD (54.3% versus 38.3%), GN (6.3% versus 0.9%), and interstitial nephritis (7.0% versus 0.6%) (all P<0.05). Patients from developed countries were less often treated with dialysis (15.5% versus 30.2%; P<0.001) and started dialysis later after AKI diagnosis (2.0 [interquartile range, 0.75-5.0] days versus 0 [interquartile range, 0-5.0] days; P=0.02). Hospital mortality was 22.0%, and 13.3% of survivors were dialysis dependent at discharge. Independent risk factors associated with hospital mortality included older age, residence in an emerging country, use of vasopressors (emerging countries only), dialysis and mechanical ventilation, and higher APACHE score and cumulative fluid balance (developed countries only). A lower probability of renal recovery was associated with residence in an emerging country, higher APACHE score (emerging countries only) and dialysis, while mechanical ventilation was associated with renal recovery (developed countries only). CONCLUSIONS: This study contrasts the clinical features and management of AKI and demonstrates worse outcomes in emerging than in developed countries. Differences in variations in care may explain these findings and should be considered in future trials.

Microscopic Polyangiitis following Silicone Exposure from Breast Implantation.

We describe a case of a patient who developed microscopic polyangiitis (MPA) in the setting of exposure to silicone after breast implantation. A 57-year-old Hispanic woman was admitted to our hospital with complaints of fever, cough, and hemoptysis. She had undergone silicone breast implantation two years prior to presentation. She was diagnosed as having microscopic polyangiitis (MPA) based on acute progressive renal failure, hematuria, pulmonary hemorrhage, and positivity for myeloperoxidase-anti-neutrophil cytoplasmic antibody (ANCA). A renal biopsy performed showed focal segmental necrotizing and crescentic glomerulonephritis. The patient received high dose steroids, cyclophosphamide, and plasmapheresis with remarkable clinical response. This case report raises the possibility of the development of MPA after silicone exposure from breast implantation.

Prediction of preeclampsia-bench to bedside.

Hypertensive disorders of pregnancy (HDP) constitute the most common medical condition seen during gestation, effecting 1 in 10 pregnancies in the USA. Traditionally, preeclampsia (PE) is defined as a new onset of hypertension and either proteinuria or end-organ dysfunction after 20 weeks of gestation in a previously normotensive woman. Preeclampsia is a potentially life-threatening condition with widespread underlying endothelial dysfunction, and accompanying inflammation, vasoconstriction, and platelet activation. Women with preeclampsia are at an increased risk for life-threatening complications and progression to eclampsia. Worldwide, 10 to 15 % of maternal deaths are from preeclampsia and related complications. Traditionally, diagnosis of preeclampsia is made based upon presence of risk factors and clinical criteria. Diagnosis is challenging in asymptomatic women early in pregnancy as well as in nulliparous women as they lack obstetric history; however, it is well known that women with previous preeclampsia have a 14.7 % risk of the condition in the second pregnancy. Prediction of those at risk and early diagnosis is crucial to enable close surveillance of high-risk women in order to improve maternal and fetal outcomes. There has been much advance in our understanding of the pathogenesis of PE and in the field of angiogenic markers. However, no one test meets the criteria for a good biomarker. A multiparametric approach appears to be optimal as we await newer systems biology approaches to give us better insight into the pathogenesis of the disease.

Anemia management trends in hospital-based dialysis centers (HBDCs), 2010 to 2013.

BACKGROUND: Few data have been reported on anemia management practices in hospital-based dialysis centers (HBDCs), which are uniquely different from other freestanding dialysis centers. Examining data from HBDCs would help determine if HBDCs and the general US dialysis population have similar trends related to how anemia is managed in dialysis patients. OBJECTIVE: Given recent changes in the prescribing information of erythropoiesis-stimulating agents (ESAs) and in end-stage renal disease-related health policy and reimbursement, this study describes trends in anemia management practices in HBDCs from January 2010 through March 2013. METHODS: Electronic medical records of 5404 adult hemodialysis patients in 50 US-based HBDCs were analyzed retrospectively. Patients included in the study cohort were aged ≥18 years and had at least 1 hemoglobin (Hb) measurement and 1 dose of an ESA between January 2010 and March 2013. End points included Hb concentration, darbepoetin alfa dosing, epoetin alfa dosing, and iron biomarkers (transferrin saturation and ferritin) and dosing. RESULTS: From 2010 to 2013, mean monthly Hb levels declined from 11.4 to 10.7 g/dL; the percentage of patients with mean monthly Hb levels <10 g/dL increased from 11.3% to 24.4%; and the percentage of patients with mean monthly Hb levels >12 g/dL declined from 30.1% to 11.2%. The median darbepoetin alfa cumulative 4-week dose also declined 38.8%, and the weekly epoetin alfa dose declined 24%. From January 2010 to March 2013, the percentage of patients with transferrin saturation >30% increased from 35.8% to 43.6%, the percentage of patients with ferritin levels >500 ng/mL increased from 62.0% to 77.9%, the percentage of patients with ferritin levels ≥800 ng/mL increased from 28.9% to 47.3%, and the median cumulative 4-week intravenous iron dose increased 50%. CONCLUSIONS: These study results support growing evidence that meaningful changes have occurred over the last 3 years in how anemia is clinically managed in US hemodialysis patients. Study limitations include that changes in patient clinical/demographic characteristics over time were not controlled for and that study findings may not be applicable to HBDCs that have different patient populations and/or do not use an electronic medical record system. Continuing to evaluate anemia management practices in HBDCs would provide additional information on the risks and benefits of anemia care. Consistent with national data, the findings from this study indicate that from 2010 to 2013, HBDCs modified anemia management practices for dialysis patients, as evidenced by reductions in mean monthly Hb levels and ESA dosing and by increases in iron biomarkers and dosing.

Acute kidney injury in pregnancy-current status.

Pregnancy-related acute kidney injury (PR-AKI) causes significant maternal and fetal morbidity and mortality. Management of PR-AKI warrants a thorough understanding of the physiologic adaptations in the kidney and the urinary tract. Categorization of etiologies of PR-AKI is similar to that of acute kidney injury (AKI) in the nonpregnant population. The causes differ between developed and developing countries, with thrombotic microangiopathies (TMAs) being common in the former and septic abortion and puerperal sepsis in the latter. The incidence of PR-AKI is reported to be on a decline, but there is no consensus on the exact definition of the condition. The physiologic changes in pregnancy make diagnosis of PR-AKI difficult. Newer biomarkers are being studied extensively but are not yet available for clinical use. Early and accurate diagnosis is necessary to improve maternal and fetal outcomes. Timely identification of "at-risk" individuals and treatment of underlying conditions such as sepsis, preeclampsia, and TMAs remain the cornerstone of management. Questions regarding renal replacement therapy such as modality, optimal prescription, and timing of initiation in PR-AKI remain unclear. There is a need to systematically explore these variables to improve care of women with PR-AKI.

Estimating the child health equity potential of improved sanitation in Nepal.

BACKGROUND: Access to improved sanitation plays an important role in child health through its impact on diarrheal mortality and malnutrition. Inequities in sanitation coverage translate into health inequities across socio-economic groups. This paper presents the differential impact on child mortality and diarrheal incidence of expanding sanitation coverage across wealth quintiles in Nepal. METHODS: We modeled three scale up coverage scenarios at the national level and at each of the 5 wealth quintiles for improved sanitation in Nepal in the Lives Saved Tool (LiST): equal for all quintiles, realistically pro-poor and ambitiously pro-poor. RESULTS: The results show that equal improvement in sanitation coverage can save a total of 226 lives (10.7% of expected diarrhea deaths), while a realistically pro-poor program can save 451 child lives (20.5%) and the ambitiously pro-poor program can save 542 lives (24.6%). CONCLUSIONS: Pro-poor policies for expanding sanitation coverage have the ability to reduce population level health inequalities which can translate into reduced child diarrheal mortality.

Podocyturia as a diagnostic marker for preeclampsia amongst high-risk pregnant patients.

Urinary podocyte (podocyturia) has been studied as a diagnostic marker for preeclampsia. We sought to validate its use in preeclampsia and in differentiating it from other high risk pregnancy states. We studied an obstetric population at high risk to develop preeclampsia (study group) and uncomplicated pregnancies (control group) by analyzing their urine sediment for podocytes within 24 hours of delivery. Podocytes were identified by immunohistochemistry using the podocyte-specific protein synaptopodin. Of the 56 patients who were enrolled, 29 patients were diagnosed with preeclampsia, 9 patients had hypertensive conditions such as chronic and gestational hypertension, 6 patients had Type I/II and gestational diabetes mellitus, 3 patients were classified as others, and 9 patients exhibited uncomplicated pregnancies. Podocyturia was identified in 11 out of 29 (38%) of patients with preeclampsia/eclampsia, 3 out of 9 (33%) with gestational and chronic hypertension, and 3 out of 6 (50%) with Type I/II and gestational diabetes mellitus. None of the 9 patients (0%) with uncomplicated pregnancies demonstrated podocyturia. The sensitivity and specificity of podocyturia for preeclampsia were found to be 38% and 70%. Our study showed that podocyturia does not appear to be a sensitive nor a specific marker to diagnose preeclampsia.

Hypertension in pregnancy: a comprehensive update.

Hypertensive disorders of pregnancies remain a central public health concern throughout the world, and are a major cause of maternal mortality in the developing world. Although treatment options have not significantly changed in recent years, insight on the pathogenesis of preeclampsia/eclampsia has been remarkable. With improved animal models of preeclampsia and large-scale human trials, we have embarked upon a new era where angiogenic biomarkers based on mechanism of disease can be designed to assist in early diagnosis and treatment. There is also a growing recognition of how elusive the diagnosis of eclampsia can be, especially in the postpartum period. Proper treatment of these patients depends heavily on the correct diagnosis, especially by the emergency physician. Finally, large epidemiologic studies have revealed that preeclampsia, once thought to be a self-limited entity, now appears to portend real damage to the cardiovascular and other organ systems in the long term. This review will present the latest update on our understanding of the various hypertensive disorders of pregnancies and their treatment options.

Does timing of dialysis in patients with ESRD and acute myocardial infarcts affect morbidity or mortality?

BACKGROUND AND OBJECTIVES: Patients with ESRD have an increased incidence of coronary events with a relatively higher risk for mortality after acute myocardial infarction (AMI). We evaluated whether it is safer to delay dialysis in AMI or if delay poses separate risks. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We conducted a retrospective review of 131 long-term hemodialysis patients who had AMI and were admitted between 1997 and 2005 at three New York City municipal hospitals. Patients were separated into three groups on the basis of time between cardiac symptoms and first dialysis (<24 h, 24 to 48 h, and >48 h). RESULTS: A total of 17 (13%) patients died, 10 (59%) of whom had either hypotension or an arrhythmia during their first cardiac care unit dialysis. Although these groups were comparable in acuity and cardiac status, there were no findings of increased morbidity (26, 36, and 20%, respectively) or mortality (11, 18, and 13%, respectively), despite differences in the timing of each group's dialysis. We found that previous cardiac disease, predialysis K+, DeltaK+ after dialysis, and APACHE scores were significantly higher in patients with peridialysis morbidity. CONCLUSIONS: We conclude that there is no increased morbidity with early dialysis in AMI, but rather close attention needs to be paid to the rate of decrease in serum potassium in patients with ESRD and their level of acuity when undergoing dialysis.

Photogeneration of charge carriers and their transport properties in poly[bis(p-n-butylphenyl)silane].

The photocarrier generation mechanism and mobility in poly[bis(p-n-butylphenyl)silane] (PBPS) thin films doped with a variety of electron acceptors are studied by time-resolved microwave conductivity (TRMC) measurements. It was found that fullerene is a suitable electron acceptor for PBPS as it provides the highest product of photocarrier generation yield phi and mobility Sigmamu under excitation at 532 and 355 nm. The observed high phiSigmamu value of 4.5 x 10(-3) cm(2)/(V s) under excitation at 193 nm (6.39 eV) can be attributed to the direct ionization of PBPS molecules. The photoinduced electron transfer between C(60) and PBPS was investigated in a solution sample by laser flash photolysis under excitation at 532 nm. On the basis of the extinction coefficient of PBPS(*+), transient absorption of PBPS(*+) provides a maximum value of phi of 0.83% for the electron-transfer reaction from PBPS to (3)C(60). On the basis of this value of phi, the intrinsic intrachain mobility of holes on the PBPS backbone is estimated to be higher than 1.7 x 10(-2) cm(2)/(V s), suggesting the presence of a high conducting path along the Si backbone of PBPS.

Radiation chemical studies on thermosensitive N-isopropylacrylamide and its polymer in aqueous solutions.

The pulse radiolysis technique has been employed to determine the initiation and propagation rates of different transient species involved in the polymerization of N-isopropylacrylamide (NIPA) in aqueous solutions. Polymerization by anionic mechanism has been observed to be faster than by the free-radical mechanism. The kinetic, spectroscopic and redox properties of the transient species formed upon reaction of primary radiolytic species of water radiolysis with NIPA have been evaluated. The one-electron oxidation potential for the formation of a radical cation is quite high (>2 V), but the one-electron reduction potential is low (in the range of -0.3 to -0.7 V). The radical anion of NIPA is able to undergo an electron-transfer reaction with MV(2+), and has a pK(a) value of 3.2. The tert-butyl alcohol radical was also able to initiate polymerization. Gamma radiation-induced polymerization studies showed that the reaction of H(.)/(.)OH/e(aq)(-)/tert-butyl alcohol radicals with NIPA results in a nearly equal yield of the gel fraction. The hydrogel is observed to have very little swelling below pH 3 and above pH 10. The linear polymer of NIPA formed by irradiating dilute aqueous solution is found to be a thermosensitive polymer with lower a critical solution temperature (LCST) of ~33 degrees C. The diameters of polymer molecules were 290 and 20 nm at temperature below and above LCST, respectively.