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Biomedical subjects

N Kapoor

Publications and source records attributed to N Kapoor.

At least 19 recordsLinked to original sources
PubMed2005

Elevated dark adaptation thresholds in traumatic brain injury.

PRIMARY OBJECTIVE: To expand upon earlier findings of elevated dark adaptation (scotopic) thresholds in photosensitive individuals with traumatic brain injury (TBI). METHODS AND PROCEDURES: To assess scotopic thresholds in individuals with TBI (n = 17) manifesting varying degrees of photosensitivity (mild, moderate or marked), but without retinal dysfunction, to those of non-photosensitive, visually-normal individuals (n = 21) using a hand-held dark adaptometer. MAIN OUTCOMES AND RESULTS: The group mean scotopic threshold for the TBI group was significantly higher than that of the visually-normal group. Over 50% (nine out of 17) of the TBI group exhibited elevated thresholds. There was no correlation between the threshold value and degree of photosensitivity. CONCLUSION: The elevated scotopic thresholds suggest an abnormality in cortical gain control. An anomalous adaptive response may develop due to cortical damage, thereby attenuating subjective light sensation.

Adult↗
PubMed2005

Predictive value of alarm features in a rapid access upper gastrointestinal cancer service.

AIMS: (i) To determine the value of individual alarm features for predicting cancer in subjects referred to a rapid access upper gastrointestinal cancer service; and (ii) to develop a clinical prediction model for cancer and to prospectively validate this model in a further patient cohort. METHODS: Patient demographics, referral indications, and subsequent diagnosis were recorded prospectively. Logistic regression analyses were employed to determine the predictive value of individual alarm features in an evaluation cohort of 1852 consecutive cases. The potential impact of applying a modified set of referral criteria was then examined in a validation cohort of 1785 patients. RESULTS: Evaluation cohort: mean age was 59 years; cancer prevalence 3.8%; and serious benign pathology 12.8%. Dysphagia (odds ratio (OR) 3.1), weight loss (OR 2.6), and age >55 years (OR 9.5) were found to be significant predictive factors for cancer but the value of other accepted alarm features was more limited. In particular, uncomplicated dyspepsia in those over 55 years was a negative predictive factor for cancer within this high risk cohort (OR 0.1). Validation cohort: the clinical prediction model would have selected 92% of cancer patients for fast track investigation while reducing the "two week rule" workload by 572 cases (31%). CONCLUSIONS: Fast track endoscopy in subjects fulfilling current criteria for suspected upper gastrointestinal malignancy results in a significant yield of cancer ( approximately 4%) and serious benign diseases such as peptic ulceration, strictures, and severe oesophagitis (13%). However, the predictive value of individual features for cancer varies widely. Uncomplicated dyspepsia in older subjects was a poor predictor of cancer. Application of narrower referral criteria for accessing fast track services may reduce pressures while retaining high sensitivity for cancer.

Adolescent↗
PubMed2002

Alteration in ouabain-sensitive sodium potassium pump of erythrocytes during pregnancy induced hypertension: a kinetic study.

The erythrocytes are widely used as model cells for studies of sodium-potassium pump (Na(+)-K(+) pump) in health and disease. Hence, to explore the possible role of the Na(+) transport across the cell membrane in the pathogenesis of pregnancy-induced hypertension (PIH), the present study was conducted to assess the Na(+)-K(+) pump functions in relation to its intrinsic kinetic properties using erythrocytes (RBC). Erythrocyte sodium concentration in pregnancy-induced hypertensive women was significantly (p<0.01) lower in comparison to normotensive pregnant women. On the contrary erythrocyte potassium was significantly higher (p<0.01) in PIH women as compared to normotensive pregnant women. Observed alterations in Na(+) and K(+) concentrations in erythrocytes were associated with significantly (p<001) increased Ouabain-sensitive sodium efflux rate and rate constants in erythrocytes from PIH women. Further, kinetic studies revealed that increased Ouabain-sensitive efflux rate constant in RBC from PIH women was accompanied by increased maximal velocity (V(max)) of Na(+)-K(+) pump. However, the affinity constant (K(m)) was unaltered in both the groups. Therefore, these findings suggest that increased Na(+)-K(+) pump activity in RBC of PIH women could be due to either increased numbers of Na(+)-K(+) pump units of increased numbers of active subunits of Na(+)-K(+) pump possibly due to specific plasma factors in PIH women.

Enzyme Inhibitors↗
PubMed2002

Dissatisfaction with consent for diagnostic gastrointestinal endoscopy.

INTRODUCTION: Little is known about patients' perspectives on the amount of information they receive prior to diagnostic gastrointestinal endoscopies. Our unit's policy for obtaining consent consists of initially posting an information leaflet to the patient followed by subsequent explanation of the procedure on arrival for the test. The consent form is signed by the patient immediately prior to the test. METHODS: A questionnaire survey was conducted to assess patient perception and satisfaction with the amount of information received before diagnostic endoscopy. RESULTS: The information was obtained from 127 of the 175 questionnaires that were distributed. Whereas 97% had read the information leaflet, only 52% had read the consent form before signing it. 64/127(51%) felt dissatisfied because they would have wanted more information while 3% were dissatisfied because they would have liked less information relating to one or more aspects of the test. Dissatisfaction was higher in patients who had not read the consent form (p < 0.001) and those with some formal education (p = 0.01). CONCLUSIONS: Patients who did not read the consent form were more dissatisfied. Strategies to improve the rate of reading this document may increase patient satisfaction.

Endoscopy, Gastrointestinal↗
PubMed2001

Bronchoscopic instillation of surfactant in acute respiratory distress syndrome.

Abnormalities of surfactant action in acute respiratory distress syndrome (ARDS) result in decreased lung compliance and significant hypoxemia. Several case reports and small studies suggest that there is an improvement in patients with ARDS following the administration of surfactant. However, there is no clear-cut ideal method for surfactant administration. The bronchoscopic administration of surfactant may represent an effective method of surfactant delivery in ARDS. Bronchoscopic instillation offers the theoretical advantages that the surfactant may be distributed directly to the desired regions of the lung, a more economical use of surfactant, and the opportunity to lavage leaked serum proteins prior to instillation. Surfactant has been administered in adults with success. We present a case of initial improvement in oxygenation index, ventilation index, and mechanical ventilatory support in a pediatric patient with ARDS following the bronchoscopic administration of surfactant.

Bronchoscopy↗
PubMed2001

Hematopoietic stem cell transplantation for severe combined immune deficiency.

Hematopoietic stem cell transplantation (HSCT) has been the definitive therapy for severe combined immune deficiency (SCID) since the first successful transplant for SCID in 1968. Improvements in the use of HSCT to treat patients with SCID are continuing. For example, during the last 5 years, the first successful in-utero HSCT, and the first success with gene therapy have occurred in patients with SCID. Debate still continues about the role of pretransplantation therapy for SCID patients, and the biology of post-HSCT immune reconstitution is under investigation.

Genetic Therapy↗
PubMed2001

Hematopoietic stem cell transplantation: current status of old issues.

Since 1968 hematopoietic stem cell transplantation (HSCT) has progressed from an experimental to standard therapeutic procedure. There are many obstacles to the successful outcome of HSCT procedures. Some of these obstacles are lack of healthy histocompatible donors, graft versus host disease, graft rejection and infections. Many advances have been made to overcome these obstacles with significant success. However, these issues and associated problems continue to persist at different levels as the field evolves with expanding indications for HSCT, use of alternative sources for hematopoietic stem cells and alternative transplant procedures. Newer interventions have allowed us to overcome some of these obstacles.

Graft Rejection↗
PubMed2001

Adenoviral infections and a prospective trial of cidofovir in pediatric hematopoietic stem cell transplantation.

Adenoviral (ADV) infections are increasingly recognized as a cause of morbidity and mortality in pediatric hematopoietic stem cell transplantation (HSCT). We reviewed our experience with ADV infections in HSCT patients hospitalized for transplantation at Childrens Hospital Los Angeles January 1998 through December 1998. ADV was detected in 47% of patients, with recipients of HSCT from alternative donors (matched unrelated, unrelated cord, and mismatched related donors) being more frequently culture positive than recipients of HSCT from matched siblings (62% versus 27%, P = .04). Detection of ADV from 2 or more sites was associated with organ injury, eg, hemorrhagic cystitis, enteritis, and hepatitis. Because of the high incidence of ADV culture-positive patients and the lack of effective anti-ADV therapy, we initiated a prospective trial to evaluate cidofovir (CDV) in the treatment of ADV infections in HSCT recipients. Eight patients were enrolled on a dosage schedule of 1 mg/kg 3 times weekly. AD of these patients eventually achieved long-term viral suppression and clinical improvement, although 6 patients needed prolonged CDV therapy for up to 8 months before CDV could be stopped without ADV recurrence. We did not observe dose-limiting nephrotoxicity, and the discontinuation of the drug was not required in any patients. Prospective controlled trials to further define the role of CDV in the treatment of ADV infections in HSCT patients are warranted.

Adenoviridae Infections↗
PubMed2000

The foveal 'crowding' effect: physics or physiology?

It has been known for some time that both foveal and peripheral visual acuity is higher for single letters than for letters in a row. Early work showed that this was due to the destructive interaction of adjacent contours (termed 'crowding' or contour interaction). It has been assumed to have a neural basis and a number of competing explanations have been advanced which implicate either high-level or low-level stages of visual processing. Our results suggest a much simpler explanation, one primarily determined by the physics of the stimulus rather than the physiology of the visual system. We show that, under conditions of contour interaction or 'crowding', the most relevant physical spatial frequency band of the letter is displaced to higher spatial frequencies and that foveal vision tracks this change in spatial scale.

Form Perception↗
PubMed2000

Gene therapy for adenosine deaminase deficiency.

The clinical gene therapy trials for adenosine deaminase (ADA) deficiency have defined both the potential benefits and the present limitations of gene therapy with hematopoietic stem cells (HSC). Current clinical results indicate that (a) both umbilical cord blood and neonatal bone marrow HSC can be transduced with murine retroviral-based vectors, (b) the transduced HSC can engraft in nonmyeloablated patients, (c) the frequency of HSC transduction/engraftment is low (1/10,000), (d) an in vivo selective advantage can exist for transduced T lymphoid progeny, and (e) the transduced ADA gene is not expressed in nondividing T lymphocytes. Improving the clinical results of gene therapy for ADA deficiency and other genetic diseases involving HSC will require (a) developing new vectors that express the transduced gene in nondividing cells and (b) increasing the frequency of stable HSC transduction.

Adenosine Deaminase↗
PubMed2000

Contour interaction in fovea and periphery.

It has been known for some time that both foveal and peripheral visual acuity are higher for single letters than for letters in a row. Early work showed that this was due to the destructive interaction of adjacent contours (termed contour interaction). It has been assumed to have a neural basis, and a number of competing explanations have been advanced that implicate either high-level or low-level stages of visual processing. Our previous results for foveal vision suggested a much simpler explanation, one determined primarily by the physics of the stimulus rather than the physiology of the visual system. We show that, under conditions of contour interaction or crowding, the most relevant physical spatial-frequency band of the letter is displaced to higher spatial frequencies and that foveal vision tracks this change in spatial scale. In the periphery, however, beyond 5 degrees, the physical explanation is not sufficient. Here we show that there are genuine physiological lateral spatial interactions, which are due to changes in the spatial scale of analysis.

Adult↗
PubMed2000

T cell depleted haploidentical bone marrow transplantation for the treatment of children with severe combined immunodeficiency.

Severe combined immunodeficiency (SCID) is fatal in early childhood if unrecognized and if not treated. The aim was to determine the efficacy of T cell depleted bone marrow transplantation (TCD BMT) in the treatment of children with SCID. Eleven children diagnosed with SCID received histocompatible related donor bone marrow transplantation--HRD BMT (group I). Thirty seven children diagnosed with SCID who did not have histocompatible donors were treated with TCD haploidentical parental bone marrow transplantation (BMT) (group II). TCD was performed by in vitro soybean lectin agglutination followed by E-rosette depletion. Patients were longitudinally assessed for the presence and function of T and B lymphocytes. In group I all children survived. The mean age of children in this group at the time of HRD BMT was 15.4 months. All surviving patients normalized their specific T cell function. Two out of 11 require treatment with intravenous immunoglobulin i.v. Ig. In group II 17 out of 37 (46%) children survived. At the time of TCD BMT the mean age of survivors was 7.5 months, vs. 11.4 months in patients who died. Death was caused most commonly by opportunistic infections, Epstein-Barr virus induced lymphoproliferative disease (EBV-LPD), and graft versus host disease (GvHD). Seventeen out of 17 surviving patients recovered normal numbers of CD3+ cells and antigen specific T cell function. Five out of 17 never recovered their B cell function and require i.v. Ig injections. Early diagnosis, prevention or treatment of opportunistic infections, and enhancement of immune recovery will be necessary to improve survival in patients with SCID treated with TCD BMT.

Adolescent↗
PubMed1999

Immunological recovery post-hematopoietic stem cell transplantation: role of prophylactic prevention of infection in post-transplant period.

Immunological recovery post-hematopoietic stem cell transplantation is variable. This depends upon the type of transplantation, source of hematopoietic stem cells for transplantation, prophylactic treatment for graft-versus-host disease and ongoing therapy for the treatment of graft-versus-host disease with immunosuppressive agents. Periodic numerical and functional assessment of recovery of the immune system after transplantation can identify the patients with inadequate immune system who are at risk for development of infectious complications. These patients should receive prophylactic therapy to decrease infection-related morbidity and mortality associated with transplantation procedures.

Bacterial Infections↗
PubMed1999

Defective anticarbohydrate antibody responses to naturally occurring bacteria following bone marrow transplantation.

The long-term recipients of allogeneic bone marrow transplantation (BMT) are at an increased risk of death due to bacterial infections. We evaluated the anticarbohydrate antibody responses of BMT recipients to a naturally occurring bacterial carbohydrate, polyribose phosphate (PRP). The recipients of autologous BMT achieved protective anti-PRP levels (>100 ng/mL) by 3 years after transplantation, with a pattern consistent with a recapitulation of the ontogeny of anticarbohydrate antibody responses. None of the six recipients of unrelated BMT who were off immunosuppressive therapy had protective anti-PRP levels, though their response to a protein antigen (tetanus toxoid) was normal. Of 48 recipients of histocompatible BMT, 22 (46%) had protective anti-PRP antibody levels, whereas 13 (27%) recipients who were >3 years post-BMT did not have protective levels. Therefore, all unrelated recipients and a significant proportion of histocompatible recipients without clinical graft-vs.-host disease had persistent and prolonged defects in their capacity to produce antibodies to naturally occurring bacterial carbohydrate antigens. These results suggest that allogeneic BMT recipients should be longitudinally evaluated for their anticarbohydrate antibody responses and that patients with defective antibody responses should receive prophylactic antibiotics or replacement immunoglobulin therapy or both to reduce their risk of late bacterial infections.

Adolescent↗
PubMed1999

The occurrence of ocular and visual dysfunctions in an acquired brain-injured patient sample.

BACKGROUND: Acquired brain injury (ABI) is a general term referring to brain injury occurring secondary to trauma, stroke, or post-surgical complications. This paper reports on the occurrence of various ocular and visual conditions in an ABI patient sample. METHODS: The subjects for this study were 62 brain-injured adults who resided in two extended care facilities in the New York area. Subjects ranged from 19 to 70 years of age. The standard protocol for the visual evaluation incorporated a patient interview; cover test; refraction; and assessment of visual acuity, ocular motility, accommodation, binocularity, visual fields, color vision, contrast sensitivity, pupils, and anterior and posterior segments. RESULTS: Results were reported as a ratio comparing the occurrence of a condition in our ABI sample relative to that in a reference normal population (where normative data are available) and as a comparison to other published data on ABI samples. An increased occurrence of exo deviations, oculomotor dysfunctions, and vertical deviations was evident. An elevated occurrence of dry eye, blepharitis, optic nerve pathologies, and visual field deficits was also manifest. CONCLUSION: Our patient sample demonstrates that certain ocular and visual conditions occur more frequently among ABI patients in comparison to a random, adult population.

Accommodation, Ocular↗
PubMed1998

Extracorporeal photochemotherapy for treatment of drug-resistant graft-vs.-host disease.

Extracorporeal photochemotherapy (EP) is a therapeutic approach to the treatment of drug-resistant graft-vs.-host disease (GVHD) that uses the known immunosuppressive and immunomodulatory effects of ultraviolet light. In 1990, we initiated a pilot study to evaluate the efficacy and safety of EP in patients with refractory GVHD. Between 1991 and 1996, six patients with acute grade IV liver GVHD, 12 patients with chronic following acute GVHD, and six patients with de novo chronic GVHD were treated with EP. All patients had failed to respond to conventional GVHD immunosuppressive drug therapy of cyclosporine and prednisone. The six patients with acute liver GVHD had also received antithymocyte globulin (ATG); therapy for chronic GVHD included thalidomide in eight patients, psoralen plus ultraviolet A in five patients, and ATG in two patients. All patients with acute liver GVHD had progressive liver failure with short survival despite frequent EP. The response rate with EP treatment was 3 of 6 for patients with de novo chronic GVHD and 3 of 12 for patients with chronic following acute GVHD. Three patients with bronchiolitis obliterans had either no response or no documented disease progression while undergoing EP. Side effects of EP were minor and included gastrointestinal upset frequently, catheter-related sepsis in four patients, increased red blood cell and platelet transfusion requirements in one patient, and leukopenia in two patients. EP was discontinued in three patients because of side effects, including GI upset in one patient and bone marrow suppression in two patients. Side effects were reversible with the discontinuation of EP. We were unable to correlate response to EP with the level of methoxypsoralen, number of lymphocytes treated, or pattern of pre- and posttreatment CD4/CD8 ratio. We concluded that EP has some efficacy in the treatment of drug-resistant chronic GVHD, with minor overall toxicity.

Adolescent↗
PubMed1998

T lymphocytes with a normal ADA gene accumulate after transplantation of transduced autologous umbilical cord blood CD34+ cells in ADA-deficient SCID neonates.

Adenosine deaminase-deficient severe combined immunodeficiency was the first disease investigated for gene therapy because of a postulated production or survival advantage for gene-corrected T lymphocytes, which may overcome inefficient gene transfer. Four years after three newborns with this disease were given infusions of transduced autologous umbilical cord blood CD34+ cells, the frequency of gene-containing T lymphocytes has risen to 1-10%, whereas the frequencies of other hematopoietic and lymphoid cells containing the gene remain at 0.01-0.1%. Cessation of polyethylene glycol-conjugated adenosine deaminase enzyme replacement in one subject led to a decline in immune function, despite the persistence of gene-containing T lymphocytes. Thus, despite the long-term engraftment of transduced stem cells and selective accumulation of gene-containing T lymphocytes, improved gene transfer and expression will be needed to attain a therapeutic effect.

Adenosine Deaminase↗