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Biomedical subjects

V Varma

Publications and source records attributed to V Varma.

At least 19 recordsLinked to original sources
PubMed2000

Myeloid metaplasia presenting as a splenic mass: report of a case with fine-needle aspiration cytology.

Myeloid metaplasia, i.e., the formation of bone marrow elements outside of the medullary cavity, may occur in any patient with anemia, regardless of the etiology of the anemia itself. The spleen is frequently the site of myeloid metaplasia, and it may present with varying degrees of splenomegaly; however, no cases have been reported where this entity presented as an isolated splenic mass. Our case was a 79-yr-old man who presented with anemia and a splenic mass by CT scan and who underwent fine-needle aspiration (FNA) of that mass. The smears revealed megakaryocytes admixed with other hematopoietic elements. No fatty elements were identified in the smears. We conclude that splenic myeloid metaplasia may present as a discrete splenic mass lesion, and may be diagnosed using the FNA technique.

Aged↗
PubMed1997

Lysine as helix C-capping residue in a synthetic peptide.

The structure of the synthetic peptide CH3CO(Leu-Ser-Leu-Leu-Leu-Ser-Leu)3Lys-NH2 in trifluoroethanol/water 60/40 (volume ratio) was characterized by two-dimensional nmr spectroscopy. The peptide, closely related to the amphiphilic helix models designed by W. F. De-Grado and co-workers to mimic protein ion channels [(1988) Science, Vol. 240, p. 1177-1181], folds into a regular helix spanning residues 1-20. Evidence for a helix C-terminal capping conformation, involving the terminal lysine residue, was observed from Overhauser effects and checked for consistency by restrained molecular dynamics simulations. The side-chain amino group of Lys22 forms a hydrogen bond with the carbonyl of Leu18, and the distorted helical geometry of the terminal dipeptide allows the inclusion of a water bridge between the backbone NH of the Lys22 residue and the carbonyls of Leu19 and Ser20.

Amino Acid Sequence↗
PubMed1997

Endoscopic management of pancreatic diseases.

Endoscopic management has recently been used for a variety of chronic pancreatic diseases. We used this approach in five patients with pancreatic diseases (calcific pancreatitis 2, pancreatic pseudocyst 3). Nasocystic drain was placed in a patient with pancreatic pseudocyst at the tail end of the pancreas; a 5 Fr stent was placed over 0.021"/0.035" guide wire in the main pancreatic duct in the others. All patients had relief of pain. Nasocystic drain led to resolution of pseudocyst, perisplenic collection and pleural effusion. Endoscopic treatment is safe and effective in various pancreatic disorders.

Adolescent↗
PubMed1996

Structural analysis of the lipopolysaccharide from Vibrio cholerae O139.

The lipopolysaccharide (LPS) from Vibrio cholerae O139 was deacylated with KOH. The following structure of the oligosaccharide resulting from this treatment was established on the basis of monosaccharide and methylation analyses, 1H, 13C and 31P 1D and 2D NMR experiments and 1D analogues of 3D NOESY-TOCSY and 3D TOCSY-NOESY experiments. [formula: see text] 'C' is a beta-L-threo-hex-4-enuronopyranosyl residue. Hep is L-glycero-D-manno-heptose, QuiN is 2-amino-2,6-dideoxy-D-glucose, GlcN is 2-amino-2-deoxy-D-glucose, Glc is D-glucose, Fru is D-fructose, and Kdo is 3-deoxy-D-manno-2-octulosonic acid. All sugars are pyranoses except fructose which is furanosidic. The fructose residue was localised after deacylation of the LPS with anhydrous hydrazine, methylation, acid methanolysis, and remethylation using deuterated iodomethane. The elucidation of this structure allowed for a direct comparison to the previously determined structure for Vibrio cholerae O1 lipid A-core region. The two structures are almost identical, and, therefore, this study is consistent with the genetic data for the biogenesis of strain O139 from O1. Furthermore, the identification of a structural analogue to the capsular polysaccharide of O139 in the outer core of the LPS in conjunction with the identification of colitose as a constituent of the LPS, provides additional evidence that the O-antigen and capsular polysaccharide of this strain may share the same repeat unit.

Carbohydrate Conformation↗
PubMed1995

Application of two-dimensional NMR spectroscopy and molecular dynamics simulations to the conformational analysis of oligosaccharides corresponding to the cell-wall polysaccharide of Streptococcus group A.

This paper describes the use of a protocol for conformational analysis of oligosaccharide structures related to the cell-wall polysaccharide of Streptococcus group A. The polysaccharide features a branched structure with an L-rhamnopyranose (Rhap) backbone consisting of alternating alpha-(1-->2) and alpha-(1-->3) links and D-N-acetylglucosamine (GlcpNAc) residues beta-(1-->3)-connected to alternating rhamnose rings: [formula: see text] Oligomers consisting of three to six residues have been synthesized and nuclear magnetic resonance (NMR) assignments have been made. The protocol for conformational analysis of the solution structure of these oligosaccharides involves experimental and theoretical methods. Two-dimensional NMR spectroscopy methods (TOCSY, ROESY and NOESY) are utilized to obtain chemical shift data and proton-proton distances. These distances are used as constraints in 100 ps molecular dynamics simulations in water using QUANTA and CHARMm. In addition, the dynamics simulations are performed without constraints. ROE build-up curves are computed from the averaged structures of the molecular dynamics simulations using the CROSREL program and compared with the experimental curves. Thus, a refinement of the initial structure may be obtained. The alpha-(1-->2) and the beta-(1-->3) links are unambiguously defined by the observed ROE cross peaks between the A-B',A'-B and C-B,C'-B' residues, respectively. The branch-point of the trisaccharide CBA' is conformationally well-defined. Assignment of the conformation of the B-A linkage (alpha-(1-->3)) was problematic due to TOCSY relay, but could be solved by NOESY and T-ROESY techniques. A conformational model for the polysaccharide is proposed.

Carbohydrate Conformation↗
PubMed1994

A new fiducial alignment system to overlay abdominal computed tomography or magnetic resonance anatomical images with radiolabeled antibody single-photon emission computed tomographic scans.

BACKGROUND: The use of computed tomography (CT) or magnetic resonance (MR) to overlay or register uptake patterns displayed by single-photon emission computed tomography (SPECT) with specific underlying anatomy has the potential to improve image interpretation and decrease diagnostic reading errors. The authors have developed a method that will allow the selection of a region of interest on MR or CT images that correlates with SPECT antibody images from the same patient. This method was validated first in phantom studies and subsequently was used on three patients with suspected colorectal carcinoma. METHODS: Two patients were injected with the technetium-99m-labeled 88BV59 immunoglobulin G human antibody, and the third patient was injected with the iodine-131-labeled 16.88 immunoglobulin M human antibody. CT or MR scans were obtained before antibody infusion, and subsequent SPECT scans were obtained on the first or fourth day after infusion. A customized body cast with landmarks was used for each patient during the CT, MR, and SPECT scans to match slice positions for all scanning modalities. Corresponding fiducial landmarks were identified on axial images. A computer graphics program was written to match and overlay corresponding landmarks for each imaging modality. The image registration accuracy was measured by comparing fiducial marker separations (center to center) on the registered scans. This separation uncertainty was 1-2 mm for CT-MR and 3-4 mm for CT-SPECT phantom studies. RESULTS: For patient studies, the fiducial alignment uncertainty was 3-4 mm for axial CT-SPECT and MR-SPECT images, and 6-8 mm for sagittal CT-SPECT and MR-SPECT images. The accuracy of the anatomic alignment of the patient and image registration system was +/- 1 cm in the medial-lateral axis and +/- 2 cm in the cranial-caudal direction. CONCLUSIONS: This type of image analysis may resolve uncertainties with the anatomic correlation of SPECT images that otherwise may be regarded as questionable when SPECT is used alone for radioimmunodiagnosis.

Colorectal Neoplasms↗
PubMed1993

Convergent synthesis of an elusive hexasaccharide corresponding to the cell-wall polysaccharide of the beta-hemolytic Streptococcus group A.

A convergent synthesis of a hexasaccharide corresponding to the cell-wall polysaccharide of the beta-hemolytic Streptococcus Group A is described. The strategy relies on the preparation of a key linear trisaccharide unit beta-D-GlcpNAc-(1-->3)-alpha-L-Rhap-(1-->2)-alpha-L-Rhap which has previously resisted our efforts. The trisaccharide functions both as a glycosyl acceptor and donor to give an elusive hexasaccharide. This fully functionalized unit can serve, in turn, as a glycosyl acceptor or donor for the synthesis of higher-order structures. Deprotection gives a hitherto unknown hexasaccharide for use as a hapten in immunochemical studies. The characterization of all compounds by high-resolution 1H and 13C NMR spectroscopy is also described.

Carbohydrate Conformation↗
PubMed1993

Y chromosome loss in esophageal carcinoma: an in situ hybridization study.

Carcinoma of the esophagus shows a strong male predominance and other epidemiologic differences from cancers arising at other sites. In this study, the prevalence of Y chromosome loss in 29 carcinomas of the esophagus and 53 carcinomas arising elsewhere in the aerodigestive tract was assessed by in situ hybridization of formalin-fixed paraffin-embedded tissue sections. Absence of the Y chromosome was defined as (1) negative staining for Y in neoplastic cells with positive staining for Y in immediately adjacent nonneoplastic epithelial and stromal cells, (2) positive staining of neoplastic cells with control probes for chromosomes X and 17, and (3) similar results at different stringencies and levels of protein digestion. According to these criteria, absence of the Y chromosome was observed in 13 of 14 (93%) adenocarcinomas of the esophagus, 8 of 13 (62%) squamous cell carcinomas of the esophagus, and 5 of 53 (9%) carcinomas arising in other sites. For the neoplasms examined, Y chromosome deletion was strongly and selectively associated with carcinomas, particularly adenocarcinomas, of the esophagus (P < .0001). These findings suggest that Y chromosome loss may be pathogenetically significant in these neoplasms.

Adenocarcinoma↗
PubMed1992

Convergent synthesis of higher-order oligosaccharides corresponding to the cell-wall polysaccharide of the beta-hemolytic Streptococci group A. A branched hexasaccharide hapten.

A convergent synthesis of a hexasaccharide corresponding to the cell-wall polysaccharide of the beta-hemolytic Streptococci Group A is described. The strategy relies on the preparation of a key branched trisaccharide unit alpha-L-Rhap-(1----2)-[beta-D-GlcpNAc-(1----3)]-alpha-L-Rhap which functions both as a glycosyl acceptor and donor. The hexasaccharide is obtained after only three glycosylation reactions. This fully functionalized unit can serve, in turn, as a glycosyl acceptor or donor for the synthesis of higher-order structures. Deprotection gives a hexasaccharide for use as a hapten in immunochemical studies. The characterization of all compounds by high resolution 1H- and 13C-n.m.r. spectroscopy is also described.

Carbohydrate Sequence↗
PubMed1989

Clinical and hemodynamic significance of left ventricular diastolic volume changes by exercise radionuclide ventriculography in coronary artery disease.

Recent studies have suggested that left ventricular (LV) dilatation during exercise radionuclide ventriculography may identify coronary artery disease (CAD). Coronary anatomy and LV end-diastolic pressure at catheterization were compared with results of supine exercise radionuclide ventriculography in 66 patients evaluated for chest pain. Forty-six patients had significant CAD (greater than 75% diameter stenosis) and 20 patients were normal. Radionuclide ventriculography was performed within 18 hours of catheterization, at rest and at peak exercise. Relative LV end-diastolic volumes were extrapolated from end-diastolic counts. LV end-diastolic counts increased during exercise in 19 of 20 normal subjects. In patients with CAD, LV end-diastolic counts increased in 35 (group A) and decreased in 11 (group B). The percent change in LV end-diastolic counts from rest to exercise, rest ejection fraction, exercise ejection fraction and rest LV end-diastolic pressure for each group were 20 +/- 23%, 60 +/- 13%, 67 +/- 13% and 8 +/- 3 mm Hg in normal subjects; 20 +/- 20%, 50 +/- 12%, 47 +/- 13% and 12 +/- 4 mm Hg in group A; and -9 +/- 8%, 54 +/- 21%, 49 +/- 18% and 21 +/- 7 mm Hg in group B (mean +/- standard deviation). An increase in LV end-diastolic counts was unrelated to ejection fraction response or presence of underlying CAD but only correlated to rest LV end-diastolic pressure (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗
PubMed1982

Hepatobiliary scanning in hemobilia-induced acute cholecystitis.

Radionuclide scanning of the hepatobiliary tree is highly accurate for the detection of patients with acute cholecystitis. Hemobilia, a rare complication of percutaneous liver biopsy, may result in blood clots within the biliary canaliculi. Such clots, like gallstones, may occlude the ducts and produce a clinical syndrome indistinguishable from acute cholecystitis. A patient with acute cholecystitis resulting from hemobilia following percutaneous biopsy of the liver is described. The diagnosis of acute cholecystitis secondary to blood clots was made with technetium 99mTc Iprofenin (Pipida [Sn]) scintigraphy. The patient was treated conservatively, and follow-up Pipida scan 6 weeks later demonstrated normal hepatobiliary function.

Adult↗
PubMed1982

Use of the flexible sigmoidoscope in women with previous pelvic irradiation.

Pelvic irradiation has been reported to be a risk factor for colonic malignancy. We performed flexible sigmoidoscopy with serial pinch biopsies in 20 asymptomatic women treated with irradiation for cervical cancer more than 10 years ago in order to determine the feasibility of the technique and to detect late radiation effects. The examination was well tolerated by 14 (70%) of the patients, and the instrument was passed to 40 cm in 14 (74%) of 19 women. Abnormal mucosal or vascular changes were found in 12 (60%) and nonspecific microscopic abnormalities were seen in 18 (90%) of the 20 women.

Colonic Neoplasms↗
PubMed1981

Multiple juvenile polyposis. A study of the pathogenesis of juvenile polyps and their relationship to colonic adenomas.

Solitary juvenile polyps are common lesions whose pathogenesis is poorly understood. Multiple juvenile polyposis is characterized by large numbers of these lesions either confined to the colon or throughout the gastrointestinal tract. A study of two cases of multiple juvenile polyposis provided fresh insight into the pathogenesis of juvenile polyps and their relationship to colonic adenomas. Mucosal ulceration in very early lesions, together with glandular epithelial calcification, suggested that impaired cell renewal resulting from disturbed regenerative kinetics may predispose to surface epithelial erosion, setting in motion a cycle of ulceration, inflammation, and granulation tissue formation. We postulate that a dyskinetic continuum may link juvenile, "metaplastic," and adenomatous polyps. The finding in our second case of multiple adenomatous lesions, including a villoglandular polyp, emphasizes the neoplastic potential of juvenile polyposis.

Adenoma↗