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Biomedical subjects

A Saxena

Publications and source records attributed to A Saxena.

At least 163 records · Page 9Linked to original sources
PubMed1997

Predictors of arterial thrombosis after diagnostic cardiac catheterization in infants and children randomized to two heparin dosages.

Arterial thrombosis is the most frequent major complication of percutaneous arterial catheterization in children. We prospectively studied the effect of randomized dosage of heparin, 50 IU/kg-group I and 100 IU/kg-group II, on the incidence of arterial thrombosis in 366 children and analysed the various factors which may influence the occurrence of this complication. The age of patients ranged from 17 d to 11 yr (mean age 39.5 +/- 40.9 mo) and mean weight was 11.2 +/- 7.8 kg (range 3 to 39 kg). The incidence of arterial thrombosis was 9.8% in group I and 9.3% in group II (P = NS). There was no statistical difference in precatheterization and procedure variables in the two groups and also in the group with absent pulse (n = 35) to the group with pulse present post cath (n = 331). There were 24.9% infants in our study and 14.3% of these had arterial thrombosis. The loss of pulse was more often seen with more number of attempts at arterial puncture (P < 0.001), absence of back bleed at the end of the procedure (P < 0.001), and increased duration of catheterization (P < 0.01). Use of larger sheath size in a given weight and body surface area of children increased incidence of arterial thrombosis. The administration of heparin 50 IU/kg was equally efficacious to heparin 100 IU/kg. Of the patients with arterial thrombosis, 23 responded with intravenous heparin and 12 needed streptokinase. There was no bleeding or haematoma. Thus our study shows that less attempt for arterial puncture, use of smaller sheath size, maintaining shortest procedure time and ensuring back bleed minimises incidence of arterial thrombosis post catheterization.

Anticoagulants↗
PubMed1997

Ductus arteriosus aneurysm in the adult: role of computed tomography in diagnosis.

Aneurysm of the ductus arteriosus has been reported in children more frequently than in adults [1-4]. The rarity of the lesion explains the low rate of recognition by the radiologist, especially because symptoms are non-specific in most cases. Clinically and radiologically, aneurysm of the ductal diverticulum can be confused with other mass lesions in the aorticopulmonary window. We report CT features of two ductal aneurysm in the adult with atypical presentation.

Adult↗
PubMed1997

Immunoglobulin G subclasses and susceptibility to allosensitization in humans.

Understanding the cellular basis of allosensitization is important because persistence of cytotoxic alloreactive antibodies significantly decreases the chances for receiving a second kidney graft and has a detrimental effect on graft survival rates. In this study, serum levels of IgG subclasses were compared within three groups of uremic patients with different levels of allosensitization (panel reactive antibody level > or = 70%, 10-65% and < or = 10%). All the non-sensitized patients had already lost at least one graft indicating resistance to allosensitization by the previous graft. In addition, the in vitro T-cell proliferation and immunoglobulin M and G subclass production were studied after activation by pokeweed mitogen and alloantigens. The patients' demographics were comparable. The results show that all serum IgG subclass levels in the three groups were comparable and within the range of normal control. Similarly, T-cell proliferation and the in vitro production of IgM was not significantly different. The lymphocytotoxic activity present in each IgG subclass was not associated with an increase in the respective serum subclass level or the in vitro production of the same subclass in the sensitized patients. The data indicate that humoral immunity, as reflected by subclass immunoglobulin levels, is, in fact, normal, in the three groups and that sustenance of cytotoxic antibody production reflects a specific immune response controlled by factors other than intrinsic B-cell abnormality.

Adult↗
PubMed1997

Mitral valve reconstruction: eight years' experience in 531 patients.

Between January 1988 and June 1996, a total of 531 patients underwent reconstruction of the mitral valve for mitral regurgitation (MR) with or without mitral stenosis (MS). Of these patients, 423 (79.7%) were aged under 30 years. The cause of mitral regurgitation was rheumatic in 471 patients (88.7%). Combined lesion (MR + MS) was present in 296 cases (55.7%). Operative mortality rate was 5.1% (27 patients) and there were 11 late deaths. Ten patients have been reoperated on for residual MR. All surviving patients were followed up by physical examination and echocardiography; follow up was 93% complete. The actuarial survival rate at 84 months was 93.1% and event-free survival rate was 87.3%. We conclude that mitral valve repair in the young rheumatic population is feasible, the probability of reoperation is low, and the symptomatic relief is gratifying.

Adolescent↗
PubMed1996

Crystallization and preliminary X-ray analysis of a low density lipoprotein from human plasma.

Single crystals of human plasma low density lipoprotein (LDL), the major transport vehicle for cholesterol in blood, have been produced with a view to analysis of the three-dimensional structure by x-ray crystallography. Crystals with dimensions of approximately 200 x 100 x 50 microm have been reproducibly obtained from highly homogeneous LDL particle subspecies, isolated in the density ranges d = 1.0271-1. 0297 g/ml and d = 1.0297-1.0327 g/ml. Electron microscopic imaging of ultrathin-sectioned preparations of the crystals confirmed the existence of a regular, quasihexagonal arrangement of spherical particles of approximately 18 nm in diameter, thereby resembling the dimensions characteristic of LDL after dehydration and fixation. X-ray diffraction with synchrotron radiation under cryogenic conditions revealed the presence of well resolved diffraction spots, to a resolution of about 29 A. The diffraction patterns are indexed in terms of a triclinic lattice with unit cell dimensions of a = 16. 1 nm, b = 39.0 nm, c = 43.9 nm; alpha = 96.2 degrees, beta = 92.1 degrees, gamma = 102 degrees, and with space group P1.

Crystallography, X-Ray↗
PubMed1996

Abnormalities of p16, p15 and CDK4 genes in recurrent malignant astrocytomas.

Abnormalities in the p16, p15 and CDK4 genes that regulate transition through the G1 phase of the cell cycle have been implicated in the malignant progression of astrocytomas. The results of the present study demonstrate that dysfunction of these genes also occurs during recurrence of glial tumors that were highly malignant at first presentation. Analysis of 10 matched pairs of high grade malignant astrocytomas and their subsequent recurrences identified three distinct groups. The primary and recurrent tumors in Group A did not show structural alterations in the p16, p15 or CDK4 genes, whereas homozygous codeletion of p16 and p15 was observed in both primary and recurrent tumors in Group B. The primary tumors in Group C had a normal profile of p16, p15 and CDK4 at presentation. Upon recurrence, however, the tumors sustained either deletion of p16 alone or codeletion of both p16 and p15 or amplification of CDK4. Analysis of the molecular differences between primary anaplastic astrocytomas/glioblastomas and their subsequent recurrences, which are clinically indistinguishable, may provide better therapeutic options for treatment.

Astrocytoma↗
PubMed1996

Surgical experience with total correction of tetralogy of Fallot in infancy.

Fifty two patients less than one year old with tetralogy of Fallot underwent primary repair between January 1991 and December 1994. Age range was three to twelve months (mean 10.09 +/- 2.01 months) and body weight ranged from 4.5 to 9 kg (mean 8.38 +/- 2.79 kg). Transatrial-transpulmonary repair was performed in 36 patients and the classical transventricular approach was used in 16 patients. Six patients underwent emergency surgery for severe cyanosis and spells. Five patients had left pulmonary artery plasty for pulmonary artery bifurcation stenosis and two out of the five patients who had anomalous coronary arteries needed a right ventricle to pulmonary artery conduit. Mean post repair peak right ventricular/systemic pressure ratio was 0.74 +/- 0.18 in the transventricular group and 0.71 +/- 0.26 in the transatrial-transpulmonary group. There were three hospital deaths. Follow-up ranged from 3 to 46 months (mean 21.18 months). Forty patients underwent echocardiography and twenty patients underwent cardiac catheterisation six to eighteen months after surgery. Mean right ventricular outflow tract gradient on echocardiography was 20.35 +/- 10.12 and, at cardiac catheterisation, 17.51 +/- 13.49 mmHg with mean post repair peak right ventricle/left ventricle pressure ratio of 0.44 +/- 0.11. These were significantly less than the values obtained in the operating room. Only one patient had residual ventricular septal defect with left to right shunt of 1.6:1 at cardiac recatheterisation. There was one late death after reoperation for residual obstruction. Encouraging results with primary repair of tetralogy of Fallot in infancy prompt us to continue this policy in suitable cases.

Body Weight↗
PubMed1996

Enhanced surface hardness by boron implantation in Nitinol alloy.

Boron implantation into Nitinol alloy has a potential for developing improved Nitinol root canal instruments with excellent cutting properties, without affecting their superelastic bulk-mechanical properties. The surface hardness of nickel-titanium (NiTi) alloy, also known as "Nitinol" (50 atm% nickel+50 atm% titanium), has been improved by ion-beam surface modification. With an implantation dose of 4.8 x 10(17) boron/cm2, a high concentration of boron (30 atm%) is incorporated into NiTi alloy by 110 keV boron ions at room temperature (25 degrees C). Boron-implanted and unimplanted (pure) Nitinol alloys show surface hardness of 7.6 +/- 0.2 and 3.2 +/- 0.2 GPa, respectively, at the nanoindentation depth of 0.05 micron. The ion-beam-modified NiTi alloy exceeds the surface hardness of stainless steel.

Boron↗
PubMed1996

Anti-CD18 antibodies improve cardiac function following cardiopulmonary bypass in dogs.

PURPOSE: Cardiopulmonary bypass is associated with activation of neutrophils, which may adhere to vascular endothelium causing lung, heart, and brain injury. We tested whether blocking neutrophil adherence would improve organ function following cardiopulmonary bypass in dogs. MATERIALS AND METHODS: All dogs received a standard anesthetic, and then one group (n = 6) received 2 hours of cardiopulmonary bypass followed by 4 hours of observation. A second group (n = 6) received a monoclonal antibody (6 mg/kg) to CD18, a neutrophil adherence factor, immediately before cardiopulmonary bypass. A third group (n = 6) did not receive cardiopulmonary bypass or antibody. RESULTS: Using flow cytometry we found that the antibody bound essentially all neutrophil CD18 sites. All three groups had similar gas exchange and hemodynamics. Lung and heart histology results were similar between groups. By echocardiography, five animals receiving cardiopulmonary bypass alone showed regional wall abnormalities, whereas only one receiving antibody showed wall motion abnormality (P < .05). Following cardiopulmonary bypass, intracellular myocardial pH was higher (P < .05) in the antibody-treated group compared with the group that had cardiopulmonary bypass alone (7.23 +/- 0.05 v 7.07 +/- 0.07 respectively). CONCLUSION: Monoclonal antibodies to CD18 can prevent the deterioration in cardiac function routinely observed following cardiopulmonary bypass.

Analysis of Variance↗
PubMed1996

Pulmonary edema following intrauterine methylene blue injection.

Methylene blue is a commonly used dye in diagnostic procedures such as fistula detection, delineation of body tissues during surgery and for checking the patency of fallopian tubes. Many such dyes interfere with accurate measurement of oxygen saturation by a pulse oximeter. We report here a case in which methylene blue hot only interfered with pulse oximetery but also caused pulmonary edema in an ASA grade 1 patient.

Absorption↗
PubMed1996

Renovascular hypertension resulting from nonspecific aortoarteritis in children: midterm results of percutaneous transluminal renal angioplasty and predictors of restenosis.

OBJECTIVE: Nonspecific aortoarteritis is a major cause of renovascular hypertension in children. Stenosis of the renal artery is usually long and begins at the origin of that artery. We retrospectively studied the midterm results of angioplasty during treatment and defined the predictors of restenosis in 40 stenoses in 24 children. MATERIALS AND METHODS: All patients had clinically inactive disease and hemodynamically significant stenosis causing hypertension. Midterm results were analyzed by the life table method. The effect of clinical, angiographic, and technical factors on the restenosis rate was tested by the Kaplan-Meir survival method. RESULTS: Technical success was obtained without complications in 38 (95%) of the lesions in 22 (92%) of the patients. The stenosis decreased from 89 +/- 7% to 11 +/- 12%, the pressure gradient fell from 97 +/- 27 to 10 +/- 10 mm Hg, and blood pressure decreased from 174 +/- 14/112 +/- 11 to 141 +/- 13/88 +/- 11 mm Hg (p < .001). Clinical benefit was seen in all patients with technically successful angioplasty. During the follow-up period (33 +/- 22 months), restenosis was seen in eight lesions (20%). The predicted cumulative patency rate at 5 years was 71%. Adverse effects on the rate of restenosis were associated with male sex (p = .04), stenosis beginning at the origin of the renal artery (p = .01), and more than 20% residual stenosis after angioplasty (p = .02). CONCLUSION: Our results show that hypertension in children with renal artery stenosis caused by nonspecific aortoateritis can be safely treated by renal angioplasty with excellent midterm results. A long stenosis beginning at the origin of the artery predisposes to restenosis, but repeat dilatation often produces lasting benefit.

Adolescent↗
PubMed1996

Testicular extramedullary myeloid cell tumor in a patient with myelodysplastic syndrome.

We report herein a case of extramedullary myeloid tumor arising bilaterally in the testes of a 66-year-old man, who had previously been diagnosed with myelodysplastic syndrome. Light microscopy of the testicular neoplasm demonstrated a tumor composed of large, slightly polygonal cells with pale blue to weakly eosinophilic cytoplasm. The tumor cells were immunoreactive for CD45, myeloperoxidase, lysozyme, CD43, and MB2. Many of the cells also expressed chloroacetate esterase. Peripheral blood and bone marrow findings were consistent with chronic myelomonocytic leukemia (FAB-CMML), particularly in the most recent material, which showed clear cellular dysplasia and an increase in the percentage of blasts in the bone marrow (15% to 20% of all nucleated cells). This case of extramedullary myeloid tumor is unusual in view of the patient's age and the testicular location. It emphasizes the importance of including extramedullary myeloid tumor in the differential diagnosis of histologically undifferentiated large-cell tumors, as well as a need to use a broad panel of immunohistochemical stains in such cases.

Aged↗