Multidrug resistance and myelomonocytic leukaemia in gaucher's disease.
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Bone Marrow Examination↗
Biomedical subjects
B Krishnan
Publications and source records attributed to B Krishnan.
A new role for cryptochrome in a Drosophila circadian oscillator.
Cryptochromes are flavin/pterin-containing proteins that are involved in circadian clock function in Drosophila and mice. In mice, the cryptochromes Cry1 and Cry2 are integral components of the circadian oscillator within the brain and contribute to circadian photoreception in the retina. In Drosophila, cryptochrome (CRY) acts as a photoreceptor that mediates light input to circadian oscillators in both brain and peripheral tissue. A Drosophila cry mutant, cryb, leaves circadian oscillator function intact in central circadian pacemaker neurons but renders peripheral circadian oscillators largely arrhythmic. Although this arrhythmicity could be caused by a loss of light entrainment, it is also consistent with a role for CRY in the oscillator. A peripheral oscillator drives circadian olfactory responses in Drosophila antennae. Here we show that CRY contributes to oscillator function and physiological output rhythms in the antenna during and after entrainment to light-dark cycles and after photic input is eliminated by entraining flies to temperature cycles. These results demonstrate a photoreceptor-independent role for CRY in the periphery and imply fundamental differences between central and peripheral oscillator mechanisms in Drosophila.
Animals↗
Diagnosing primary and metastatic renal cell carcinoma: the use of the monoclonal antibody 'Renal Cell Carcinoma Marker'.
The diagnosis of primary or metastatic renal cell carcinoma (RCC) can be difficult, especially in small biopsies, because of the wide variety of histologic appearances and clinical presentations that RCC can assume. An immunomarker specific for RCC is currently not available. We tested the relevant diagnostic use of the Renal Cell Carcinoma Marker (RCC Ma), a monoclonal antibody, against a normal human proximal tubular brush border antigen. Immunostaining using RCC Ma and the avidin-biotin-peroxidase complex technique was performed on archival tissues from primary and metastatic tumors of renal or nonrenal origin. A total of 122 of 153 primary RCCs (79.7%) were positive [clear cell (84%), papillary (96%), chromophobe (45%), sarcomatoid (25%), and collecting duct (0%)], with > or =10% of tumor cells stained in 93% of cases. None of the 64 primary renal tumors other than RCC, including 15 oncocytomas, was positive. Fifteen of 146 (10.2%) nonrenal primary tumors were positive (5 of 17 breast tumors, 8 of 8 parathyroid adenomas, and 2 of 7 embryonal carcinomas). Forty-two of 63 (67%) metastatic RCCs were positive with > or =10% of cells being stained in 83% of them. Two of 108 (2%) metastases from tumors other than RCCs were positive, both of which were metastatic breast carcinomas; however, only 10% (2 of 19) of metastatic breast carcinomas were positive. RCC Ma is an excellent marker for primary RCC, which should facilitate its diagnosis in a small biopsy. Although RCC Ma remains highly specific (98%) for metastatic RCC, a negative result may not rule out metastatic RCC because of a rather low sensitivity and a focal staining pattern in some of the positive cases. RCC Ma may also facilitate the differential diagnosis between oncocytoma and other types of RCC when they are composed mostly of eosinophilic cells.
Antibodies, Monoclonal↗
Generic isolated horizons and their applications
The notion of isolated horizons is extended to allow for distortion and rotation. Space-times containing a black hole, itself in equilibrium but possibly surrounded by radiation, satisfy these conditions. The framework has three types of applications: (i) it provides new tools to extract physics from strong field geometry; (ii) it leads to a generalization of the zeroth and first laws of black hole mechanics and sheds new light on the "origin" of the first law; and (iii) it serves as a point of departure for black hole entropy calculations in nonperturbative quantum gravity.
Journal Article↗
Myxoma involving the atrial valve chordae.
Primary cardiac valve tumors are rare and comprise less than 10% of all cardiac tumors. They are, however, of clinical importance because of their unique locations. We report an unusual case of myxoma involving the tricuspid valve chordae in a young woman presenting with syncope. The myxoma was diagnosed by echocardiography and successfully removed by excision of the involved tricuspid valve chordae with valve preservation. (Curr Surg 57:357-358)
Journal Article↗
Neutrophil-rich anaplastic large cell lymphoma of T-cell lineage. A report of two cases arising in HIV-positive patients.
Neutrophil-rich anaplastic large cell lymphoma (ALCL) is an uncommon morphologic variant of ALCL. We report 2 cases of neutrophil-rich T-cell ALCL that presented as scalp masses in HIV-positive men. Histologically, the neoplastic cells extensively infiltrated the dermis and subcutaneous tissue. The neoplastic cells strongly expressed CD30 and were of T-cell lineage, positive for CD3 and CD45RO, and negative for CD20. The neoplastic cells were negative for anaplastic lymphoma kinase-1. Numerous admixed neutrophils also were present, representing up to 70% of all cells in some microscopic fields. Neither patient had peripheral blood leukocytosis. One patient had relative neutrophilia, 79% (0.79; reference range, 50%-70% [0.50-0.70]). The absolute CD4 counts were 160 cells/microL (160 x 10(6)/L) and 150 cells/microL (150 x 10(6)/L), respectively (reference range, 431-1,623/microL [431-1,623 x 10(6)/L]). Both patients were treated with multiagent chemotherapy but died of Pneumocystis carinii pneumonia within 6 months of diagnosis. In our review of the literature, we identified 5 similar T-cell cases, including 1 in an HIV-positive patient. Neutrophil-rich T-cell ALCL is a rare morphologic variant of ALCL that should be considered in the histologic evaluation of neutrophil-rich biopsy specimens.
Adult↗
Prostatic adenocarcinoma diagnosed by urinary cytology.
Prostatic adenocarcinoma rarely may involve the urinary bladder. Prostatic adenocarcinoma and high-grade transitional cell carcinoma (TCC) may coexist and account for the malignant cells seen in urinary cytology. Differentiating prostatic adenocarcinoma cells from those of TCC is important for therapy but remains difficult. A 10-year retrospective search identified 250 patients with high-grade carcinoma in urinary cytology. Among them, 6 cases of tissue-documented prostate adenocarcinoma were identified. The cytologic features of these cases were compared with those of 15 similarly documented cases of high-grade TCC. By using these criteria, 2 additional cases of prostatic adenocarcinoma were diagnosed prospectively. An oval nucleus with smooth borders; fine, powdery, evenly distributed nuclear chromatin and a large prominent nucleolus when present; and lack of significant pleomorphism are most helpful to differentiate prostatic adenocarcinoma from high-grade TCC. Recognizing these cells may be the first clue for the diagnosis of prostate adenocarcinoma.
Adenocarcinoma↗
Role of respiratory function in exercise limitation in chronic heart failure.
OBJECTIVE: To test the hypothesis that respiratory function contributes to limit maximal exercise performance in patients with chronic heart failure by using the technique of dead space loading during exercise. DESIGN: Blinded subjects underwent two maximal incremental exercise tests in random order on an upright bicycle ergometer: one with and one without added dead space. SETTING: : Tertiary-care university teaching hospital. SUBJECTS: Seven patients with stable chronic heart failure (mean +/- SEM left ventricular ejection fraction, 27 +/- 3%). RESULTS: Subjects were able to significantly increase their peak minute ventilation during exercise with added dead space when compared with control exercise (57.4 +/- 5.9 vs 50.0 +/- 5.6 L/min; p < 0.05). Peak oxygen uptake, workload, heart rate, and exercise duration were not significantly different between the added dead space and control tests. Breathing pattern was significantly deeper and slower at matched levels of ventilation during exercise with added dead space. CONCLUSION: Because patients with chronic heart failure had significant ventilatory reserve at the end of exercise and were able to further increase their maximal minute ventilation, we conclude that respiratory function does not contribute to limitation of exercise in patients with chronic heart failure.
Adult↗
Actinomyces and actinobacillus actinomycetemcomitans-Actinomyces-associated lymphadenopathy mimicking lymphoma.
We present 2 unusual cases of long-standing, extensive reactive lymphadenopathy secondary to Actinomyces infection, 1 of which was also accompanied by Actinobacillus actinomycetemcomitans-Actinomyces complex infection. To our knowledge, histologic features of lymph node involvement by these organisms have not been previously reported in the literature. One patient had extensive cervical, posterior mediastinal, and abdominal lymphadenopathy. The second patient presented with a submandibular mass and cervical lymphadenopathy. Clinical features strongly suggested lymphoma. The histologic examination of the lymph nodes from both patients revealed reactive follicular hyperplasia, marked interfollicular and capsular fibrosis, and multiple interfollicular microabscesses. Characteristic Actinomyces colonies were identified at the center of the microabscesses in deep sections. Cultures were obtained from the lymph nodes of 1 patient, and were positive for A actinomycetemcomitans. Both patients had poor dental hygiene. Lymphadenopathy subsided with antibiotic therapy and appropriate dental care.
Actinobacillus↗
Primary pulmonary mucosa-associated lymphoid tissue lymphoma with associated fungal ball in a patient with human immunodeficiency virus infection.
We describe a case of primary mucosa-associated lymphoid tissue lymphoma of the lung in a 44-year-old man with human immunodeficiency virus. Low-grade pulmonary lymphomas in human immunodeficiency virus-positive patients are rare and are described most commonly in pediatric patients. The gross, histologic, and molecular features of this unusual case are described.
Adult↗
Circadian rhythms in olfactory responses of Drosophila melanogaster.
The core mechanism of circadian timekeeping in arthropods and vertebrates consists of feedback loops involving several clock genes, including period (per) and timeless (tim). In the fruitfly Drosophila, circadian oscillations in per expression occur in chemosensory cells of the antennae, even when the antennae are excised and maintained in isolated organ culture. Here we demonstrate a robust circadian rhythm in Drosophila in electrophysiological responses to two classes of olfactory stimuli. These rhythms are observed in wild-type flies during light-dark cycles and in constant darkness, but are abolished in per or tim null-mutant flies (per01 and tim01) which lack rhythms in adult emergence and locomotor behaviour. Olfactory rhythms are also abolished in the per 7.2:2 transgenic line in which per expression is restricted to the lateral neurons of the optic lobe. Because per 7.2:2 flies do not express per in peripheral oscillators, our results provide evidence that peripheral circadian oscillators are necessary for circadian rhythms in olfactory responses. As olfaction is essential for food acquisition, social interactions and predator avoidance in many animals, circadian regulation of olfactory systems could have profound effects on the behaviour of organisms that rely on this sensory modality.
Animals↗
Induction of three-dimensional assembly of human liver cells by simulated microgravity.
The establishment of long-term cultures of functional primary human liver cells (PHLC) is formidable. Developed at NASA, the Rotary Cell Culture System (RCCS) allows the creation of the unique microgravity environment of low shear force, high-mass transfer, and 3-dimensional cell culture of dissimilar cell types. The aim of our study was to establish long-term hepatocyte cultures in simulated microgravity. PHLC were harvested from human livers by collagenase perfusion and were cultured in RCCS. PHLC aggregates were readily formed and increased up to 1 cm long. The expansion of PHLC in bioreactors was further evaluated with microcarriers and biodegradable scaffolds. While microcarriers were not conducive to formation of spheroids, PHLC cultured with biodegradable scaffolds formed aggregates up to 3 cm long. Analyses of PHLC spheroids revealed tissue-like structures composed of hepatocytes, biliary epithelial cells, and/or progenitor liver cells that were arranged as bile duct-like structures along nascent vascular sprouts. Electron microscopy revealed groups of cohesive hepatocytes surrounded by complex stromal structures and reticulin fibers, bile canaliculi with multiple microvilli, and tight cellular junctions. Albumin mRNA was expressed throughout the 60-d culture. A simulated microgravity environment is conducive to maintaining long-term cultures of functional hepatocytes. This model system will assist in developing improved protocols for autologous hepatocyte transplantation, gene therapy, and liver assist devices, and facilitate studies of liver regeneration and cell-to-cell interactions that occur in vivo.
Albumins↗
Cultures of human liver cells in simulated microgravity environment.
We used microgravity-simulated bioreactors that create the unique environment of low shear force and high-mass transfer to establish long-term cultures of primary human liver cells (HLC). To assess the feasibility of establishing HLC cultures, human liver cells obtained either from cells dissociated by collagenase perfusion or minced tissues were cultured in rotating vessels. Formation of multidimensional tissue-like spheroids (up to 1.0 cm) comprised of hepatocytes and biliary epithelial cells that arranged as bile duct-like structures along newly formed vascular sprouts were observed. Electron microscopy revealed clusters of round hepatocytes and bile canaliculi with multiple microvilli and tight junctions. Scanning EM revealed rounded hepatocytes that were organized in tight clusters surrounded by a complex mesh of extracellular matrix. Also, we observed that co-culture of hepatocytes with endothelial cells stimulate albumin mRNA expression. In summary, a simulated microgravity environment is conducive for the establishment of long-term HLC cultures and allows the dissection of the mechanism of liver regeneration and cell-to-cell interactions that resembles in vivo conditions.
Albumins↗
Does illness experience influence the recall of medical information?
Recall of a storyboard description of an unfamiliar illness was assessed in 66 healthy children and 40 children with chronic illness (cystic fibrosis or asthma). A significant interaction between verbal intelligence quotient and illness experience (p < 0.001) suggested that more able sick children may be resistant to learning new medical information.
Analysis of Variance↗
Effect of sleep deprivation on the growth hormone response to the alpha-3 adrenergic receptor agonist, clonidine, in normal subjects.
One night's sleep deprivation (SD) increased the growth hormone (GH) response to clonidine (20 ug/kg i.v.) in 11 normal men ( p < 0.005). This finding may indicate that SD enhances alpha-2 adrenergic receptor function or that the GH response to GH releasing factor in increased by SD.
Adrenergic alpha-2 Receptor Agonists↗
Mast cell involvement in gastritis with or without Helicobacter pylori infection.
BACKGROUND & AIMS: Mast cells are initiators and regulators of inflammation, but their role in the human stomach remains unclear. Therefore, the extent and distribution of mast cell involvement in gastritis with or without Helicobacter pylori infection was investigated. METHODS: Mapped biopsy specimens from 17 H. pylori-positive and 20 H. pylori-negative subjects were examined. Sections were assessed for infection and inflammation and stained with anti-human mast cell tryptase to count mucosal and epithelial mast cells. Density of mast cells in different gastric compartments, their response to infection treatment, and their relationship with other inflammatory cells were evaluated. Mast cell degranulation was evaluated by electron microscopy. RESULTS: Mast cell density was significantly greater in the mucosa with gastritis, with or without H. pylori infection, than in the mucosa of noninfected normal subjects. In the antrum, density was much greater in H. pylori-infected peptic ulcer subjects than in the other gastritis groups. It also correlated significantly with the intensity of inflammation. Mast cell degranulation was demonstrated by electron microscopy in H. pylori-infected mucosa. Mast cell density in ulcer patients decreased significantly after cure of H. pylori infection. CONCLUSIONS: Mast cells may be important effector cells in the pathogenesis of gastritis, especially in H. pylori-associated peptic ulcer.
Adult↗
Horseshoe kidney is associated with an increased relative risk of primary renal carcinoid tumor.
PURPOSE: Carcinoid tumor is a rare neoplasm of the kidney with an unknown histogenesis. Of only 31 cases previously reported in the literature 4 arose within horseshoe kidneys. We report a case of primary carcinoid tumor arising within a horseshoe kidney and discuss the unique insight it provided into the pathogenesis of this tumor. MATERIALS AND METHODS: We reviewed in detail all 31 reported cases of renal carcinoid tumor and, using reported incidence rates of horseshoe kidney, we calculated the relative risk of renal carcinoid tumor arising within a horseshoe kidney. Immunohistochemical staining for neuroendocrine related markers was performed on tissue sections from the present carcinoid tumor, the adjacent kidney and 5 control samples of normal renal parenchyma. RESULTS: Of the reported tumors 15.6% occurred in horseshoe kidneys, yielding a calculated relative risk of 62. The present tumor was multifocal, arising from the wall of a cystic lesion and possibly representing a dilated calix within the isthmus. Intestinal epithelium lining the cyst cavity exhibited multifocal neuroendocrine cell hyperplasia with an immunohistochemical profile identical to that of the carcinoid tumor cells. CONCLUSIONS: The relative risk of renal carcinoid tumor developing in a horseshoe kidney is markedly greater than that for Wilms tumor or transitional cell carcinoma. The clinical course of renal carcinoid tumor arising within a horseshoe kidney appears to be more benign than that of the nonhorseshoe variant. Our observations support the hypothesis that renal carcinoid tumors may arise from neuroendocrine cells within foci of metaplastic or teratomatous epithelium within the kidney.
Carcinoid Tumor↗