Biomedical subjects
Publications and source records attributed to D Kumar.
A retrospective analysis of 29 cases of pituitary tumours with suprasellar extension that had undergone surgery by transsphenoidal or transcranial route, was done. The correlation between age, duration of symptoms, pre- and post-operative visual acuity, visual field and suprasellar height of the tumour were analyzed. The age and duration of visual loss were found to have a bearing on the final postoperative visual outcome.
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A partially purified replicative system of pea chloroplast that replicates recombinant DNAs containing pea chloroplast origin sequences has been characterised. Polymerisation by this system is very fast and insensitive to chain terminators like dideoxynucleotides, arabinosylcytosine 5'-triphosphate, etc. Both strands of template DNA are synthesized and single-stranded DNA templates undergo more than one round of replication. When sequences of either of the two chloroplast origins of replication (OriA or OriB) are used as templates, the replicative intermediates are found to have sigma structures. Electron microscopic analysis of the sigma structures restricted with various enzymes reveals that the initiation site of in vitro replication maps near the displacement-loop regions where replication initiates also in vivo. Although the observed replication initiation in the OriA recombinant template is chloroplast-DNA-specific, the mode of replication is different from that observed in vivo with intact ctDNA. However, when the template DNA contains both the OriA and OriB sequences, the in vitro replication proceeds in the theta mode, the mode of replication usually observed in vivo.
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A 69-kDa protein with topoisomerase I activity has been homogeneously purified from the chloroplasts of pea leaves. The topoisomerase properties are detected in crude lysate of pea chloroplasts using the technique of transferring 32P radioactivity from the 32P-labeled DNA to the protein. The purified enzyme relaxes both positive and negative supercoils in topological steps of unity without requiring magnesium ions. The enzyme is sensitive to topoisomerase I-specific inhibitors like camptothecin and berenil, and unaffected by reagents like novobiocin and doxorubicin at the topoisomerase II-inhibitory dosage. In the presence of the enzyme, supercoiled DNA is nicked, and the 3'-phosphoryl end of the nick becomes covalently linked with the enzyme. A tyrosine residue of the enzyme is responsible for the covalent linkage. Rabbit antiserum raised against the 16-mer peptide spanning the active residues of human topoisomerase I recognizes the 69-kDa protein within the crude lysate of pea chloroplasts as does the antiserum to the purified 69-kDa protein. From the enzymatic characteristics, the protein has been classified as a eukaryotic type I topoisomerase.
We have previously reported that monocyte chemoattractant protein-1 (MCP-1) is the most potent histamine-releasing factor (HRF) for basophils. Macrophage inflammatory protein-1 alpha (MIP-1 alpha) has modest histamine-releasing activity. The objective of this study was to investigate whether MCP-1 and MIP-1 alpha would activate mast cells in vivo and induce a cutaneous inflammatory reaction in mice. To this goal, mouse hind footpads were separately injected with 20 microliters of human recombinant MCP-1 or MIP-1 alpha (10(-7) M). Diluent was used as a control in the second footpad. The footpad-swelling response was measured at 30 min, 1 h, and then hourly for 6 h. Both MCP-1 (2.72 +/- 0.2 vs 2.1 +/- 0.03 mm for diluent, n = 8, p < 0.02) and MIP-1 alpha (3.0 +/- 0.1 vs 2.1 +/- 0.03 mm for diluent, n = 8, p < 0.02) induced an immediate swelling reaction. The immediate reaction was followed by a sustained late reaction that peaked within 1 h and lasted for more than 6 h. Histologic examination of the footpads, obtained at hour 2, revealed that MCP-1 caused mild mononuclear cell infiltrates, moderate degranulation of mast cells, and soft tissue swelling. In contrast, MIP-1 alpha induced a severe inflammatory reaction that consisted of neutrophils, mononuclear cells, and degranulated mast cells. Electron microscope examination of the tissue revealed features of extensive mast cell degranulation by MIP-1 alpha and to a lesser extent by MCP-1. Thus, we conclude that mast cells are activated on injection of MCP-1, whereas degranulation of mast cells and recruitment of leukocytes contribute to the footpad reaction induced with MIP-1 alpha.
An infectious episode is the presenting manifestation of hairy cell leukemia (HCL) in approximately 30% of cases. Most often this is bacterial and only rare cases of opportunistic fungal infection are described. We report a patient who presented with sporotrichal involvement of multiple cutaneous sites and lymph nodes. The lesions resolved following antifungal therapy, but persisting pancytopenia and splenomegaly necessitated further hematological evaluation. A diagnosis of HCL was suspected based on morphologically characteristic hairy cells in the peripheral blood that contained tartrate resistant acid phosphatase. A bone marrow biopsy specimen had a normocellular marrow with an increase in interstitial lymphoid cells that stained with L26, MB2, and LN2 antibodies. On flow cytometry these cells were positive for the leukocyte common antigen, B cell markers, and the CD11c antigen confirming the diagnosis of HCL. We believe that this is the first report of sporotrichosis infection as a presenting manifestation of HCL.
Over a 16-year period 34 patients underwent surgery for idiopathic megarectum or megacolon; 18 had megarectum with or without megasigmoid, one megacolon only and 15 megarectum and total megacolon (nine with a previous colectomy). Ten patients underwent low rectal or anal anastomosis without pouch formation (colodistal proctostomy, eight; coloanal anastomosis, two), eight had colonic pouch-anal anastomosis (J pouch) and 14 had an ileal J pouch after restorative proctocolectomy; one underwent subtotal colectomy with ileorectal anastomosis and one loop ileostomy alone. There was one death, from intestinal obstruction 24 months after operation. Twenty-seven of 32 evaluable patients without a stoma became fully continent following resection and sphincter-saving procedures. Three of 18 had a poor result after resection for megarectum because of recurrent constipation. One of 14 patients became incontinent after restorative proctocolectomy for megacolon and megarectum and in a further four persistent abdominal distension and pain was treated by pouch excision.
Abnormalities in oesophageal, gastric and jejunal motility have been described in patients with chronic idiopathic constipation, suggesting that this may be a panenteric disorder. To test the hypothesis that ileal motility is also abnormal in constipation, terminal ileal motility was studied in ten patients and six healthy controls by prolonged and ambulant manometry. Mean(s.e.m.) phase II activity was significantly prolonged in patients compared with controls, during wakefulness (61.6(7.3) versus 19.3(3.5) per cent, P < 0.001) and sleep (44.4(9.0) versus 1.1(0.8) per cent, P < 0.001). The mean(s.e.m.) duration of phase III fronts was shorter in patients (7.9(1.8) min) than in controls (13.2(1.3) min; P < 0.001). Retrograde propagation was seen in approximately 15 per cent of all phase IIIs in patients but not in control subjects. The mean(s.e.m.) duration of postprandial activity was significantly shorter in patients than in controls (30.1(6.2) versus 130.0(68.0) min, P < 0.001). Ileal motility is abnormal in patients with chronic idiopathic constipation. This may result from an abnormality of the enteric nervous system or abnormal modulation of this system by the central nervous system.
We present a patient with dysphagia resulting from a pedunculated, spontaneous mucocele of the upper esophagus. We briefly discuss the radiologic, endoscopic, and pathologic findings of this unusual lesion.
Immunoblot detection of antibody against 47 KD cytoplasmic antigen of Candida albicans was evaluated in diagnosis of invasive candidiasis and compared to whole cell agglutination and gel diffusion tests for detection of anticandidal antibody in 64 patients. The patients included 17 with culture proved candidemia, 34 with significant candiduria (more than 10,000 colony forming units per ml of urine) and 13 with nonsignificant candiduria. Antibody against 47 KD antigen was found to be the best indicator for diagnosis of invasive candidiasis even in patients with malignancy. The sensitivity of this procedure was 82.4%, specificity 86.7%, positive predictive value 77.8%, negative predictive value 89.7% and efficacy 85.1%. The gel diffusion procedure lacked in sensitivity whereas whole cell agglutination lacked in specificity. Detection of antibody against 47 KD antigen proved to be a valuable adjunct in the diagnosis of invasive candidiasis.
This study examined changes in the risk-adjusted mortality associated with coronary artery bypass grafting procedures performed in New York State during the first 4 years of New York's Cardiac Surgery Reporting System (1989 to 1992). To track performance over time, surgeons and hospitals were subdivided into three groups on the basis of their performance in 1989. The risk-adjusted mortality for each of the three groups was computed for 1992 and compared with their 1989 mortality. The results indicate that all groups of providers exhibited large reductions in the risk-adjusted mortalities, with the groups that showed the highest initial mortalities manifesting the most improvement. However, the group rankings remained the same in 1992 as they were in 1989. For example, when the hospital groups were based on the terciles of risk-adjusted mortality observed in 1989, the risk-adjusted mortality decreased from 2.72% to 2.19% for group 1, from 4.24% to 2.51% for group 2, and from 7.12% to 2.77% for group 3. Notably, the risk-adjusted mortalities of the three groups were all significantly different from one another in 1989, but were not significantly different from one another in 1992. Another interesting finding was that the volume of operations performed by the various provider groups did not change substantially in the 4-year period.
BACKGROUND/AIMS: Scintigraphic studies give detailed information on colonic transit. In this study, several methods of presenting such data were compared and discussed. The aim of the study was to evaluate the role of geometric center (GC) and parametric images in interpretation of colonic transit studies. METHODS: Segmental colonic transit was measured in 117 patients: 50 with constipation, 24 with irritable bowel syndrome, 22 with fecal incontinence, 14 who were postsurgery, and 7 normal volunteers. 111In-labeled resin was administered in a pH-sensitive capsule, and images were acquired for 3 days. The percentage of activity in four regions of colon and in the feces was measured. RESULTS: Five patterns of colonic transit were identified (16 rapid transit, 48 intermediate, 14 generalized delay, 5 left-sided delay, and 34 right-sided delay). The geometric center (sum of fraction of activity x region number) was calculated at each time point. Using the geometric center, the groups could be differentiated (P < 0.01) except for those with left-sided delay. In individual patients, patterns of colonic transit could not be determined using the geometric center alone. Gray-scale presentation of percent activity in each region (parametric images) allowed patterns of colonic transit to be identified in individuals. CONCLUSIONS: Use of the geometric center is suitable for comparison of groups of patients, whereas parametric images identify patterns in individual patients.
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This report describes the occurrence of plasma cell neoplasia in three young HIV-positive males. Two patients presented with massive ascites. On cytologic examination of the fluid, many immature plasma cells were noted. Genotyping of fluid demonstrated clonal rearrangement of immunoglobulin heavy and kappa light chain genes in both cases. Postmortem examination on one of these revealed neoplastic plasmacellular infiltrate in various organs, including the bone marrow. The third case presented with a hemorrhagic, rapidly enlarging gingival mass with a histologic appearance of an undifferentiated neoplasm. Immunoperoxidase studies revealed positive staining only for epithelial membrane antigen. On flow cytometry, the neoplastic cells did not mark with leukocyte common antigen or any of the B- or T-cell markers. Cytoplasmic kappa light chain restriction, as well as genotypic studies, confirmed the diagnosis of anaplastic plasmacytoma. In two cases a clonal population was detected using a probe to the terminal repeat region of the Epstein-Barr virus. These results suggest that plasma cell malignancy is another AIDS-associated neoplasm. Its occurrence in this group of patients is not only coincidental.
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Comparison of argyrophilic nucleolar organizer region (AgNOR) counts has been found to yield statistically significant differences between benign and malignant conditions albeit with considerable overlap. In this study we compared the size of AgNORs and the nuclear areas, as well as the AgNOR count in 23 benign melanocytic lesions and 9 melanomas. Of these parameters, the ratio AgNOR area/nuclear area was found to be the main discriminating factor between melanoma and all the other benign groups studied, with p values of < 0.01 and no overlap. Next to it was the nuclear area, which in our study gave significant differences between the groups evaluated. The total AgNOR area and the largest AgNOR gave results comparable to the simple AgNOR counting in all groups studied, except in Spitz nevus, in which the AgNOR counts were less significant than the other parameters (p = 0.0420). We conclude that the ratio AgNOR area/nuclear area discriminates benign from malignant melanocytic lesions better than AgNOR counts or other parameters studied.
Fourteen percutaneous fine needle aspirates (FNAs) of focal liver lesions performed under ultrasound guidance at the Sultan Qaboos University Hospital (SQUH), Oman, between January 1991 and October 1992, are presented. Ten of these were cytologically diagnosed as hepatocellular carcinomas (HCC). The patients' ages ranged from 50 to 70 years and eight of these were males. The important diagnostic cytological criteria of HCC were found to be increased nucleocytoplasmic (N/C) ratio, trabecular pattern, atypical naked nuclei, bile production by malignant hepatocytes and absence of bile duct epithelium. Carcinoembryonic antigen (CEA) positivity of bile canaliculi by cross-reaction with biliary glycoprotein I (BGP I) made possible the differentiation of HCC from metastases. We stress the importance of cell blocks as these often constitute microbiopsies. Ultrasound-guided FNA of focal liver lesions is recommended as a simple, easy and quick procedure.