Search PubMed⌕ Search

Biomedical subjects

R Bansal

Publications and source records attributed to R Bansal.

At least 73 records · Page 4Linked to original sources
PubMed1994

Role of endoscopic ultrasonography in the localization of insulinomas and gastrinomas.

BACKGROUND: We have previously found selective venous sampling to be the most sensitive method to localize otherwise occult functioning endocrine tumors. However, recently we have used endoscopic ultrasonography (EUS) as the initial and in some cases the only localization study in the preoperative evaluation of proven insulinomas and of selected cases of gastrinoma. METHODS: All patients referred between April 1993 and April 1994 with a subsequently confirmed diagnosis of organic hyperinsulinism or Zollinger-Ellison syndrome (ZES) underwent EUS. Ten patients with insulinomas and six with gastrinomas were studied. Only one patient with ZES had multiple endocrine neoplasia type I. Patients with negative EUS findings had additional localization procedures including angiography and arterial stimulation tests. All but one patient underwent surgical exploration. RESULTS: Solitary insulinomas were found in all 10 patients. EUS correctly identified and localized the insulinoma in seven (70%) of 10 patients but failed to identify two pedunculated insulinomas that were easily found at exploration. Because of an incomplete examination, a single insulinoma was not detected within the parenchyma. The EUS examination correctly excluded the pancreatic gastrinomas in five patients. The sixth patient, who had multiple endocrine neoplasia type I, had two 0.5 cm tumors in the head. CONCLUSIONS: EUS is a sensitive and cost-effective technique for localization of insulinomas and may be the only study needed. In patients with ZES a negative pancreatic result suggests the likelihood of a duodenal or other extrapancreatic tumor.

Adult↗
PubMed1994

Fate of the pericardial monocusp pulmonary valve for right ventricular outflow tract reconstruction. Early function, late failure without obstruction.

Sudden change from a pressure-loaded to a volume-loaded right ventricle as a result of transannular patch reconstruction of the right ventricular outflow tract may result in early hemodynamic compromise. Tri-leaflet porcine valves in conduits function well early but typically create late obstruction. We studied the fate of a pericardial monocusp valve constructed during transannular patch reconstruction for right ventricular outflow tract obstruction in 19 patients, 2 weeks to 27 years of age (mean age 61 months). Patients had the monocusp constructed of autologous (n = 16) or bovine pericardium (n = 3) when the former was not available during transannular patch reconstruction associated with repair of tetralogy of Fallot (n = 12), pulmonary stenosis/atresia (n = 4), and truncus arteriosus (n = 3). Function of the monocusp was assessed by presence of a split-second heart sound, echocardiographic assessment of right ventricular dilatation, monocusp competence, and fluoroscopic evaluation of monocusp motion. Functional assessments were accomplished immediately after the operation and at 2, 6, 12, and 24 months after the operation. There were no operative deaths, but there was one late hospital death. Sixteen of nineteen patients (84%) had competent pulmonary monocusp valves immediately after the operation, but, by 24 months, only one of seven patients (14%) had a competent valve. No patient had monocusp stenosis. We conclude that a pericardial monocusp valve for right ventricular outflow tract reconstruction provides excellent early hemodynamic function but that these effects are limited in duration. Because late stenosis has not been seen, this inexpensive and easily constructed valve can be used as an excellent short-term adjunct to right ventricular outflow tract reconstruction.

Bioprosthesis↗
PubMed1993

The oligodendrocyte and its many cellular processes.

The oligodendrocyte (OL) is increasingly providing a model system for probing central issues of cell biology. During development, OL progenitors undergo controlled migration, proliferation and differentiation, secrete and respond to a number of growth factors, and dramatically change their cellular architecture, culminating in the formation of the myelin sheath. This review examines some facets of the OL that make it an especially attractive tool for studying many basic questions in cell biology.

Journal Article↗
PubMed1993

Pseudoaneurysms of the aorta after cardiac surgery or chest trauma.

Between March 1982 and June 1992, 17 patients (age: 21-76 years) were diagnosed with pseudoaneurysm of the thoracic aorta (PTA). Four PTAs developed post-trauma while 13 developed after aortic or cardiac surgery. Unusual presentations included: dyspnea, hoarseness, dysphagia, massive hemoptysis (2 degrees to aortobronchial fistula), massive hematemesis (2 degrees to aorto-esophageal fistula), superior vena cava syndrome, paralyzed right hemidiaphragm, and herald bleeding from the sternotomy. The interval between initial operation and recognition of PTA varied from three months to eight years while the four posttraumatic PTAs presented 5 to 26 years postinjury. The sites of postoperative PTA were: the aortotomy (3), proximal vein graft anastomosis (4), aortic cannulation site (2), and distal anastomosis of ascending aortic graft replacement (4). Aortography was very sensitive, outlining the false aneurysm in 13/13. Five patients had transesophageal echo-cardiography with one false negative. Seven patients died (41%), three from postoperative PTAs from massive hemorrhage intraoperatively and four from sepsis and multiorgan failure following repair. We conclude that patients who have previously had aortic or cardiac surgery or a history of blunt chest trauma presenting with unusual cardiorespiratory symptoms should be aggressively evaluated for PTA. Due to the magnitude of the operative problems encountered, repair of PTA is associated with a significantly high rate of mortality.

Adult↗
PubMed1992

Novel stage in the oligodendrocyte lineage defined by reactivity of progenitors with R-mAb prior to O1 anti-galactocerebroside.

The developmentally regulated appearance of surface immuno-reactivity of proligodendroblasts [oligodendrocyte progenitors reacting with monoclonal antibodies A007 and O4, but not anti-galactocerebroside (GalC), i.e., A007/O4+GalC-] to monoclonal antibodies R-mAb and O1 was studied both in culture and in vivo. In both cases staining with R-mAb shortly preceded that with O1; that is, a transient population of R-mAb+O1- cells was observed. R-mAb-O1+ cells were not detected. Differential staining with R-mAb and O1 was also noted at the subcellular level. In younger cultures in which R-mAb+ cells were first acquiring O1 immunoreactivity, many of these cells were stained by O1 only on the cell bodies and proximal portions of the processes, whereas in contrast R-mAb stained the whole cell, including the distal portions of the processes. Only in older, more mature R-mAb+ cells did O1 also stain the distal portions of processes. The expression of reactivity to R-mAb and O1 was compared to the proliferative capacity of the cells. Proliferation [assessed by bromodeoxyuridine (BrdU) incorporation] of both R-mAb+ and O1+ cells was negligible both in culture and in vivo. However, treatment of cells in culture with 10 ng/ml basic fibroblast growth factor resulted in an enhancement of proliferation of the R-mAb+ cells. Within the proliferating R-mAb+BrdU+ population, 80% of the cells were O1- (i.e., anti-galactocerebroside negative). These events occur during a critical period of development when A007/O4+ proligodendroblasts begin to become post-mitotic and express surface galactocerebroside.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Proligodendroblast antigen (POA), a developmental antigen expressed by A007/O4-positive oligodendrocyte progenitors prior to the appearance of sulfatide and galactocerebroside.

Evidence is presented for the immunological identification of a developmental antigen appearing at a critical point in the oligodendroglial lineage. Specifically, monoclonal antibody A007 recognizes cells in the oligodendrocyte lineage at two distinct stages. Analyses of purified lipid standards and lipid extracts from galactocerebroside-positive (GalC+) oligodendrocytes by enzyme-linked immunosorbent assay, lipid dot blot, and immuno-TLC demonstrated that A007 recognizes sulfatide (SUL) and seminolipid. However, neither 35SO4 incorporation into SUL nor SUL accumulation could be detected in A007-positive cells lacking galactocerebroside (i.e., A007+GalC- progenitor cells) present early in development. These data suggest that A007 also recognizes an antigen, named proligodendroblast antigen (POA), that appears during the late stage of oligodendrocyte progenitor development prior to the expression by oligodendrocytes of SUL and GalC. We have previously reported that monoclonal antibody O4 also recognizes not only SUL and seminolipid, but in addition an antigen that appears prior to the expression of SUL and galactocerebroside. In the present study all A007+ cells were also O4+ (and vice versa), and the developmental patterns of the two antibodies appeared to be identical. We conclude that (1) A007 is similar or identical to O4 with respect to its antigenic specificity, and (2) during oligodendrocyte lineage progression both antibodies react first with antigen POA on the surface of the oligodendrocyte progenitor cell prior to the expression of SUL [i.e., A007+O4+(POA+)SUL-GalC- proligodendroblasts], and only later with SUL as terminally differentiating oligodendrocytes emerge (i.e., A007+O4+SUL+GalC+ oligodendrocytes).

Animals↗
PubMed1992

Comparison of intrinsic versus paced ventricular function.

UNLABELLED: There is increasing evidence supporting the benefits of providing optimum AV delay in cardiac pacing, though controversy exists regarding its value and the benefits of intrinsic versus paced ventricular activation. This study compared various AV delays at rest in patients whose native AV delays were > or = 200 msec. Only patients with DDD pacemakers who had intact AV conduction and normal ventricular activation were included in the study. Nine patients were studied. METHODS: Ten studies were performed. Evaluation was done in AAI and DDD modes at paced heart rates of 60/min or as close as possible to the intrinsic heart rate if this was > 60/min. Stroke volume (SV) and cardiac output (CO) were measured. RESULTS: When AV sequential pacing in the DDD mode with an optimum AV delay was compared to AAI pacing with a prolonged AV interval, the average optimum AV delay in the DDD mode was 157 msec and ranged from 125 to 175 msec. The average AV interval in the AAI mode was 245 msec and ranged from 212 to 300 msec. In the DDD mode, there was an overall significant improvement in CO of 11% and SV of 9%. Patients with intrinsic AV conduction times of > 220 msec showed an overall significant improvement in CO of 13% and SV of 11%. In patients with intrinsic AV conduction times of < 220 msec, an improvement in CO of 6% and SV of 4% was seen. CONCLUSIONS: (1) An optimum AV delay is an important component of hemodynamic performance; and (2) AV sequential pacing at rest with an optimum AV delay may provide better hemodynamic performance than atrial pacing with intrinsic ventricular conduction when native AV conduction is prolonged > 220 msec.

Aged↗
PubMed1989

Multiple and novel specificities of monoclonal antibodies O1, O4, and R-mAb used in the analysis of oligodendrocyte development.

Three monoclonal antibodies that react with antigens on the surface of developing oligodendrocytes in a stage-specific manner, O1, O4 (Sommer and Schachner, 1981), and R-mAb (Ranscht et al., 1982), have been studied with respect to their specificities for a number of purified lipids. The observed specificities were consistent regardless of how the antigens were presented to the antibodies. O1 reacted with galactocerebroside, monogalactosyl-diglyceride, and psychosine and, in addition, labeled an unidentified species in rat brain extracts. R-mAb reacted with galactocerebroside, monogalactosyl-diglyceride, sulfatide, seminolipid, and psychosine; the reaction of R-mAb with sulfatide was nearly equal to that with galactocerebroside. O4 reacted with sulfatide, seminolipid, and to some extent with cholesterol. However, oligodendrocyte progenitor cells labeling with O4 that had not yet begun to express the O1 antigen failed to incorporate 35SO4 or [3H]galactose into sulfatide or seminolipid, the syntheses of which first appear in O1-positive cells. Therefore, O4 stains, in addition to sulfatide and seminolipid, and unidentified antigen that appears on the surface of oligodendrocyte progenitors prior to the expression of sulfatide and galactocerebroside. In primary cultures of rat brain, developing O4+ oligodendrocyte progenitors stained slightly earlier with R-mAb than with O1, and thus R-mAb transiently stained a larger population of oligodendrocytes than did O1. None of the three antibodies produced a detectable reaction on Western immunoblot after separation of brain proteins on reducing gels. In conclusion, the results show that O4, R-mAb, and O1 have multiple overlapping specificities, including previously unrecognized cross-reactions.

Animals↗
PubMed1989

Reversible inhibition of oligodendrocyte progenitor differentiation by a monoclonal antibody against surface galactolipids.

We have hypothesized that oligodendrocyte (OL) surface glycolipids, specifically galactocerebroside and sulfatide, play a role in the regulation of OL development by acting as sensors/transmitters of environment information. In support of this hypothesis we report here a reversible inhibition of OL progenitor cell differentiation by a monoclonal antibody [Ranscht mAb (R-mAb); Ranscht, B., Clapshaw, P. A. & Seifert, W. (1982) Proc. Natl. Acad. Sci. USA 79, 2709-2713] that reacts with these glycolipids. When isolated OL progenitors or mixed primary cultures are grown in the presence of the antibody, myelinogenic development is blocked in a dose-dependent manner at concentrations as low as 2 micrograms of IgG per ml. The inhibited cells express the OL progenitor markers O4 and vimentin but are negative for galactosylcerebroside, sulfatide, 2',3'-cyclic nucleotide 3'-phosphohydrolase, myelin basic protein, and myelin basic protein RNA expression. In contrast, the levels of total cellular protein and the expression of astrocytic glial fibrillary acidic protein in mixed cultures are not affected. Antibody-blocked cells have a distinctive morphology in which long, sparsely branched processes emanate from round cell bodies. Upon removing the perturbing antibody, the cells rapidly resume differentiation. Reverted mixed primary cultures, in which OL progenitors of several sequential developmental stages are present at the time of plating, differentiate more rapidly than control cultures, suggesting that the antibody-induced block results in a synchronization of developmental progression along the OL lineage by accumulating cells at the inhibition point. However, the normal temporal sequence of marker expression is maintained. Control studies with several other antibodies recognizing OL cell surface antigens, including HNK-1, neural cellular adhesion molecule (N-CAM), 1A9, anticholesterol, and O1, did not inhibit development. Since the inhibition occurs in highly enriched populations of OL progenitors, the inhibition does not involve cell-cell interactions between OLs and other cell types but concerns interactions of OLs with themselves, soluble factors, or OL extracellular matrix molecules and adhesion factors that provide essential environmental signals required for normal myelinogenic development.

Animals↗
PubMed1987

Genital amebiasis.

Five cases of amebiasis of the genital tract involving the cervix, vulva and penis are described. All presented as an ulcerating mass and were clinically suspected to have a tumor. In two cases the amebiasis co-existed with a carcinoma, an association which is extremely rare. The spouse of a patient with penile amebiasis was found to have amebiasis of the cervix suggesting a sexually transmitted mode of infection. The need for histopathological confirmation of all suspected genital malignancies is emphasised due to the striking resemblance of genital amebiasis to a carcinoma. The co-existence of amebiasis with carcinoma is of interest and suggests a possible etiological relationship.

Adult↗
PubMed1987

Regulated galactolipid synthesis and cell surface expression in Schwann cell line D6P2T.

Clonal cell line D6P2T, subcloned from an ethylnitrosourea-induced tumor line D6 of the rat peripheral nervous system, has been characterized with particular attention to galactolipid metabolism. Galactosylcerebroside and sulfatide synthesis and expression on the cell surface are highly regulated in D6P2T cells by mechanisms involving serum- and cyclic AMP-mediated pathways. These cells also express 2',3'-cyclic nucleotide 3'-phosphohydrolase (Wolfgram protein W1a) and laminin. In contrast, myelin basic protein and antigen HNK-1 were not detected. Line D6P2T appears to be a semi-differentiated Schwann cell model, which offers interesting possibilities for studies of galactolipid synthesis, transport, and sorting.

2',3'-Cyclic Nucleotide 3'-Phosphodiesterase↗
PubMed1987

Venous involvement in leprosy: a venographic and histopathological correlation.

Venous system involvement was studied by venography and vein histology in 30 leprosy patients irrespective of age, sex, duration of the disease, and treatment. Vascular abnormalities by venography were seen in 96.3% and by histopathological studies in 76.6% of patients. The percentage and severity of radiological and histological changes increased from tuberculoid to lepromatous in the disease spectrum. Perfect correlation of histology and venography was found in 40% of the paucibacillary patients and good correlation was found in 100%. In multibacillary patients perfect correlation was found in 29.4%, good correlation in 41.1%, and no correlation in 29.4% of the patients.

Adult↗
PubMed1985

Developmental expression of 2',3'-cyclic nucleotide 3'-phosphohydrolase in dissociated fetal rat brain cultures and rat brain.

The development in primary dissociated rat brain cultures of 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP) activity, the accumulation of CNP protein, and the number of cells accumulating this protein have been quantitatively determined as a function of time in culture. Parallel determinations have been made for the first two parameters for developing rat brain. The developmental profile of CNP enzymatic activity and amount of CNP protein in culture paralleled that observed in rat brain, in which the period of most active development occurred 7-25 days after birth. Mean CNP activities of 5.6 and 8.1 mumol/min/mg total protein were recorded for the cultures and rat brain, respectively, at their maximal levels. The corresponding mean values for the CNP protein accumulation were calculated to be 138 and 150 pmol/mg total protein, respectively. Thus maximal specific activities of the CNP protein were estimated to be about 800 and 1,000 mumol/min/mg CNP protein for culture and rat brain enzyme, respectively. Approximately three million cells expressing CNP appeared in the cultures per dissociated fetal rat brain seeded. Each CNP+ oligodendrocyte in culture had an average CNP activity of 3.2 pmol/min, and an average CNP protein content of 0.09 fmol (5.4 X 10(7) molecules), values which remained nearly constant during the course of development. Two principal conclusions are drawn from these data. First, the dissociated fetal brain culture system reproduces rather accurately the temporal developmental pattern of CNP expression occurring in the rat brain, but some important quantitative differences occur which suggest the need for additional environmental stimuli missing in these cultures. Second, the quantitative increases in CNP specific activity and amount of CNP protein occurring during oligodendrocyte differentiation in these cultures are primarily the result of increases in the number of CNP+ cells present which upon differentiation express very quickly, via an off-on regulation, steady-state levels of the enzyme.

2',3'-Cyclic Nucleotide 3'-Phosphodiesterase↗