Nasal polyps - histopathologic spectrum

Analysis of 345 polypoidal masses in nose and nasal sinuses with clinical diagnosis of nasal polyp, observed in 10 years, revealed 175 (50.7%) non- neoplastic lesions and 170 (49.3%) neoplasms. Among the non- neoplastic lesions, there were 110 cases (62.8%) of true nasal polyps including 74 cases (67.3%) of allergic polyps and 36 (32.7%) inflammatory ones. The next common non- neoplastic polyp was due to rhinosporidiosis (31.4%). Benign neoplastic lesions consisted mainly of haemangioma (45.7%), angiofibroma (23.2%), fibroma (6.2%), transitional cell papilloma, inverted papilloma, adenoma-3.9% each. Squamous cell carcinoma was the commonest malignant lesion encountered (36.6%) followed by 19.5% of adenoid cystic carcinoma,17.1% of anaplastic carcinoma and 12.2% of transitional cell carcinoma. Adeno carcinoma (4.9%), Mucoepidermoid carcinoma (2.4%), non- Hodgkin lymphoma (4.9%) and embryonal rhabdomyosarcoma (2.4%) were the other malignant lesions.

Near-grain-boundary characterization by atomic force microscopy

Characterization of near-grain boundary is carried out by atomic force microscopy (AFM). It has been observed to be the most suitable technique owing to its capability to investigate the surface at high resolution. Commercial purity-grade nickel processed under different conditions, viz., (i) cold-rolled and annealed and (ii) thermally etched condition without cold rolling, is considered in the present study. AFM crystallographic data match well with the standard data. Hence, it establishes two grain-boundary relations viz., plane matching and coincidence site lattice (CSL Sigma=9) relation for the two different sample conditions.

Quantitative analysis of agonist-dependent parathyroid hormone receptor trafficking in whole cells using a functional green fluorescent protein conjugate

Many G-protein coupled receptors (GPCRs) undergo ligand-dependent internalization upon activation. The parathyroid hormone (PTH) receptor undergoes endocytosis following prolonged exposure to ligand although the ultimate fate of the receptor following internalization is largely unknown. To investigate compartmentalization of the PTH receptor, we have established a stable cell line expressing a PTH receptor-green fluorescent protein (PTHR-GFP) conjugate and an algorithm to quantify PTH receptor internalization. HEK 293 cells expressing the PTHR-GFP were compared with cells expressing the wild-type PTH receptor in whole-cell binding and functional assays. 125I-PTH binding studies revealed similar Bmax and kD values in cells expressing either the PTHR-GFP or the wild-type PTH receptor. PTH-induced cAMP accumulation was similar in both cell lines suggesting that addition of the GFP to the cytoplasmic tail of the PTH receptor does not alter the ligand binding or G-protein coupling properties of the receptor. Using confocal fluorescence microscopy, we demonstrated that PTH treatment of cells expressing the PTHR-GFP conjugate produced a time-dependent redistribution of the receptor to the endosomal compartment which was blocked by pretreatment with PTH antagonist peptides. Treatment with hypertonic sucrose prevented PTH-induced receptor internalization, suggesting that the PTH receptor internalizes via a clathrin-dependent mechanism. Moreover, co-localization with internalized transferrin showed that PTHR-GFP trafficking utilized the endocytic recycling compartment. Experiments using cycloheximide to inhibit protein synthesis demonstrated that recycling of the PTHR-GFP back to the plasma membrane was complete within 1-2 h of ligand removal and was partially blocked by pretreatment with cytochalasin D, but not nocodazole. We also demonstrated that the PTH receptor, upon recycling to the plasma membrane, is capable of undergoing a second round of internalization, a finding consistent with a role for receptor recycling in functional resensitization.

Cell-based, high-content screen for receptor internalization, recycling and intracellular trafficking

A variety of physiologically important receptors are internalized and then recycled back to the plasma membrane by the endocytic recycling compartment. These include the transferrin receptor and many G-protein coupled receptors (GPCRs). The internalization of GPCRs is a result of agonist stimulation. A cell-based fluorescent imaging assay is described that detects and quantifies the presence of fluorescently labeled receptors and macromolecules in the recycling compartment. This High Content Screening application is conducted on the ArrayScan II System that includes fluorescent reagents, imaging instrumentation and the informatics tools necessary to screen for compounds that affect receptor internalization, recycling and GPCR activation. We demonstrate the Receptor Internalization and Trafficking application by quantifying (i) the internalization and recycling of the transferrin receptor using a fluorescently labeled ligand and (ii) the internalization of a physiologically functional model GPCR, a GFP-parathyroid hormone receptor chimera. These assays give high signal-to-noise ratios, broad dynamic ranges between stimulated and unstimulated conditions and low variability across different screening runs. Thus, the Receptor Internalization and Trafficking application, in conjunction with the ArrayScan II System, forms the basis of a robust, information-rich and automated screen for GPCR activation.

Progressive C-terminal deletions of the renal cystine transporter, NBAT, reveal a novel bimodal pattern of functional expression

Nearly identical proteins (denoted NAA-Tr, rBAT, D2, NBAT), cloned from mammalian kidneys, induce a largely sodium-independent high-affinity transport system for cystine, basic amino acids, and some neutral amino acids in Xenopus oocytes (system b0,+-like). Mutations in the human NBAT gene have been found in several type I cystinurics. In kidney, NBAT is associated with a second, smaller protein (approximately 45 kDa), and this heterodimer has been proposed to be the minimal functional unit of the renal cystine transporter (Wang, Y., and Tate, S. S. (1995) FEBS Lett. 368, 389-392). To delineate regions minimally required for functional expression in oocytes, we constructed a series of C-terminal truncated mutants of rat kidney NBAT (wild-type (WT), 683 amino acids). Expression of these mutants in oocytes yielded an unusual bimodal pattern for the induction of amino acid transport activity. Thus, initial C-terminal truncations aborted elicitation of transport activity. The next mutant in the series, Delta588-683, exhibited most of the transport-inducing potential inherent in the WT/NBAT. Further deletions again attenuated transport activity. Although both the WT/NBAT and the truncated mutant, Delta588-683, induce qualitatively similar transport systems, the two forms of the protein exhibit contrasting sensitivities toward a point mutation in which the cysteine residue at position 111 was mutated to serine. This mutation did not greatly affect induction of transport by the WT/NBAT; however, the Delta588-683 mutant was inactivated by this mutation. Our data further suggest that cysteine 111 is probably the site of disulfide linkage with an approximately 45-kDa oocyte protein producing a complex equivalent to that seen in kidney membranes.

Raf-1 physically interacts with Rb and regulates its function: a link between mitogenic signaling and cell cycle regulation

Cells initiate proliferation in response to growth factor stimulation, but the biochemical mechanisms linking signals received at the cell surface receptors to the cell cycle regulatory molecules are not yet clear. In this study, we show that the signaling molecule Raf-1 can physically interact with Rb and p130 proteins in vitro and in vivo and that this interaction can be detected in mammalian cells without overexpressing any component. The binding of Raf-1 to Rb occurs subsequent to mitogen stimulation, and this interaction can be detected only in proliferating cells. Raf-1 can inactivate Rb function and can reverse Rb-mediated repression of E2F1 transcription and cell proliferation efficiently. The region of Raf-1 involved in Rb binding spanned residues 1 to 28 at the N terminus, and functional inactivation of Rb required a direct interaction. Serum stimulation of quiescent human fibroblast HSF8 cells led to a partial translocation of Raf-1 into the nucleus, where it colocalized with Rb. Further, Raf-1 was able to phosphorylate Rb in vitro quite efficiently. We believe that the physical interaction of Raf-1 with Rb is a vital step in the growth factor-mediated induction of cell proliferation and that Raf-1 acts as a direct link between cell surface signaling cascades and the cell cycle machinery.

An endocytosed TGN38 chimeric protein is delivered to the TGN after trafficking through the endocytic recycling compartment in CHO cells

To examine TGN38 trafficking from the cell surface to the TGN, CHO cells were stably transfected with a chimeric transmembrane protein, TacTGN38. We used fluorescent and 125I-labeled anti-Tac IgG and Fab fragments to follow TacTGN38's postendocytic trafficking. At steady-state, anti-Tac was mainly in the TGN, but shortly after endocytosis it was predominantly in early endosomes. 11% of cellular TacTGN38 is on the plasma membrane. Kinetic analysis of trafficking of antibodies bound to TacTGN38 showed that after short endocytic pulses, 80% of internalized anti-Tac returned to the cell surface (t1/2 = 9 min), and the remainder trafficked to the TGN. When longer filling pulses and chases were used to load anti-Tac into the TGN, it returned to the cell surface with a t1/2 of 46 min. Quantitative confocal microscopy analysis also showed that fluorescent anti-Tac fills the TGN with a 46-min t1/2. Using the measured rate constants in a simple kinetic model, we predict that 82% of TacTGN38 is in the TGN, and 7% is in endosomes. TacTGN38 leaves the TGN slowly, which accounts for its steady-state distribution despite the inefficient targeting from the cell surface to the TGN.

Argyrophilic nucleolar organiser regions (AgNORs) in breast lesions

Nucleolar organiser regions (NORs) demonstrated by argyrophilia of NOR-proteins are indicator of cellular proliferative activity. The NORs can be identified in the nuclei as brown or black dots with silver colloidal staining technique in formalin fixed paraffin sections and in cytology smears. Seventy-five cases including 45 tissue sections and 30 fine needle aspiration cytology (FNAC) smears of benign and malignant lesions of breast have been studied to evaluate the significance and practical application of AgNOR count per nucleus. Out of 45 tissue sections 15 belonged to fibrocystic disease, 10 fibro-adenomas and 20 carcinomas and of the 30 FNAC smears, 10 were fibrocystic disease, 8 fibro-adenomas and 12 carcinomas. In fibrocystic disease the mean AgNOR count was 1.60 (FNAC group-0.75, tissue section-1.61). In fibro-adenomas it was 1.61 (FNAC-1.63, tissue section-1.59). The mean count in carcinoma was 12.10 (FNAC-12.08, tissue section-12.10). The difference in AgNOR count in fibrocystic disease and fibro-adenoma was not significant, but that between benign breast lesion and carcinoma was significant. No difference was observed between FNAC and tissue section groups in benign or malignant lesions. The simple staining technique can be used as an additional criterion to differentiate the benign and malignant lesions of breast.

Endocytosis

Mammalian cells take up extracellular material by a variety of different mechanisms that are collectively termed endocytosis. Endocytic mechanisms serve many important cellular functions including the uptake of extracellular nutrients, regulation of cell-surface receptor expression, maintenance of cell polarity, and antigen presentation. Endocytic pathways are also utilized by viruses, toxins, and symbiotic microorganisms to gain entry into cells. One of the best-characterized endocytic mechanisms is receptor-mediated endocytosis via clathrin-coated pits. This type of endocytosis constitutes the major emphasis of this review, with a brief discussion of other endocytic mechanisms and their comparison with the receptor-mediated pathway. This review describes and evaluates critically current understanding of the mechanisms of entry of plasma membrane components such as the receptor-ligand complexes and membrane lipids as well as the extracellular fluid into cells. The intracellular sorting and trafficking of these molecules upon internalization are also described. The roles of endocytosis in physiological and pathological processes are discussed. These include maintenance of cell polarization, antigen presentation, glucose transport, atherosclerosis, Alzheimer's disease, and the endocytosis of toxins and viruses.

Cysticercosis of larynx

A rare case of cysticercosis of larynx in a 50 years male presenting with hoarseness of voice is reported.

Transferrin receptor containing the SDYQRL motif of TGN38 causes a reorganization of the recycling compartment but is not targeted to the TGN

The SDYQRL motif of the cytoplasmic domain of TGN38 is involved in targeting TGN38 from endosomes to the TGN. To create a system for studying this pathway, we replaced the native transferrin receptor (TR) internalization motif (YTRF) with the SDYQRL TGN-targeting motif. The advantages of using TR as a reporter molecule include the ability to monitor trafficking, in both biochemical and microscopy experiments, using the natural ligand transferrin. When expressed in CHO cells, the SDYQRL-TR construct accumulated in juxtanuclear tubules and vesicles that are in the vicinity of the TGN. The SDYQRL-TR-containing structures, however, do not colocalize with TGN markers (e.g., NBD ceramide), and therefore the SDYQRL motif is not sufficient to target the TR to the TGN. The morphology of the SDYQRL-TR-containing juxtanuclear structures is different from the recycling compartment found in cells expressing the wild-type TR. In addition, the SDYQRL-TR-containing juxtanuclear compartment is more acidic than the recycling compartment in cells expressing the wild-type TR. The juxtanuclear compartment, however, is a bona fide recycling compartment since SDYQRL-TR was recycled back to the cell surface at a rate comparable to the wild-type TR, and sphingomyelin and cellubrevin, both of which label all compartments of the endocytic recycling pathway, colocalize with SDYQRL-TR in the juxtanuclear structures. These findings demonstrate that expression of the SDYQRL-TR construct alters the morphology and pH of endocytic recycling compartments rather than selectively affecting the intracellular trafficking pathway of the SDYQRL-TR construct. Therefore, the SDYQRL trafficking motif is not simply a molecular address that targets proteins to the TGN, but it can play an active role in determining the physical characteristics of endosomal compartments.

Microglial cells internalize aggregates of the Alzheimer's disease amyloid beta-protein via a scavenger receptor

Microglia are immune system cells associated with Alzheimer's disease plaques containing beta-amyloid (A beta). Murine microglia internalize microaggregates of fluorescently labeled or radioiodinated A beta peptide 1-42. Uptake was confirmed using aggregates of unlabeled A beta detected by immunofluorescence. Uptake of A beta was reduced by coincubation with excess acetyl-low density lipoprotein (Ac-LDL) or other scavenger receptor (SR) ligands, and Dil-labeled Ac-LDL uptake by microglia was blocked by excess A beta. CHO cells transfected with class A or B SRs showed significantly enhanced uptake of A beta. These results show that microglia express SRs that may play a significant role in the clearance of A beta plaques. Binding to SRs could activate inflammation responses that contribute to the pathology of Alzheimer's disease.

Intracellular calcium levels correlate with speed and persistent forward motion in migrating neutrophils

The relationship between cytosolic free calcium concentration ([Ca2+]i) and human neutrophil motility was studied by video microscopy. Neutrophils stimulated by a uniform concentration of an N-formylated peptide chemoattractant (f-Met-Leu-Phe) were tracked during chemokinetic migration on albumin, fibronectin, and vitronectin. [Ca2+]i buffering with quin2 resulted in significant decreases in mean speed on albumin. To further characterize the relationship between [Ca2+]i changes and motility we carried out a cross-correlation analysis of [Ca2+]i with several motility parameters. Cross-correlations between [Ca2+]i and each cell's speed, angle changes, turn strength, and persistent forward motion revealed (i) a positive correlation between [Ca2+]i and cell speed (p < 0.05), (ii) no significant correlation between turns and calcium spikes, and (iii) the occurrence of turns during periods of low speed. Significant negative correlations between [Ca2+]i and angle change were noted on the high adhesion substrates vitronectin and fibronectin but not on the low adhesion substrate albumin. These data imply that there is a general temporal relationship between [Ca2+]i, speed, and persistent motion. However, the correlations are not sufficiently strong to imply that changes in [Ca2+]i are required proximal signals for velocity changes.

Clinicopathological study of clinically undiagnosed cases of kala-azar with special reference to grading of parasites

Clinicopathological study of 34 clinically undiagnosed cases of kala-azar has been undertaken with a view to establish the diagnosis and correlate the quantitative grading of Leishmania donovani in bone marrow/splenic aspirates with clinical features and duration of disease. The ages of the patients were between 5 and 45 years. The duration of illnesses ranged from 2-24 months with 47% having 2 months' duration. Splenomegaly was less than 7 cm in 70.5% cases. Anaemia, leucopenia and mild thrombocytopenia were present in all the cases. Aldehyde test was positive in 47% cases. Bone marrow aspiration revealed the parasites in 82.3% cases. L donovani was also observed in 66.6% cases of splenic aspiration including 6 cases where bone marrow failed to reveal the parasite. Grading of the parasites in bone marrow and splenic aspirates revealed majority of the cases (73.5%) were in 3+ and 4+ grades. No correlation between splenic size and duration of illness or parasite grading was detected. Neither any positive correlation between parasite grading and duration of illness was observed.

Evidence for nonvectorial, retrograde transferrin trafficking in the early endosomes of HEp2 cells

We have previously characterized the trafficking of transferrin (Tf) through HEp2 human carcinoma cells (Ghosh, R. N., D. L. Gelman, and F. R. Maxfield, 1994. J. Cell Sci. 107:2177-2189). Early endosomes in these cells are comprised of both sorting endosomes and recycling compartments, which are distinct separate compartments. Endocytosed Tf initially appears in punctate sorting endosomes that also contain recently endocytosed LDL. After short loading pulses, Tf rapidly sorts from LDL with first-order kinetics (t1/2 approximately 2.5 min), and it enters the recycling compartment before leaving the cell (t1/2 approximately 7 min). Here, we report a second, slower rate for Tf to leave sorting endosomes after HEp2 cells were labeled to steady state with fluorescein Tf instead of the brief pulse used previously. We determined this rate using digital image analysis to measure the Tf content of sorting endosomes that also contained LDL. With an 11-min chase, the Tf in sorting endosomes was 24% of steady-state value. This was in excess of the amount expected (5% of steady state) from the rate of Tf exit after short filling pulses. The excess could not be accounted for by reinternalization of recycled cell surface Tf, implying that either some Tf was retained in sorting endosomes, or that Tf was delivered back to the sorting endosomes from the recycling compartment. The former is unlikely since nearly all sorting endosomes contain detectable Tf after an 11-min chase, even though more than one third of the sorting endosomes were formed during the chase time. Furthermore, while observing living cells by confocal microscopy, we saw vesicle movements that appeared to be fluorescent Tf returning from recycling compartments to sorting endosomes. The slow rate of exit after steady-state labeling was similar to the Tf exit rate from the cell, suggesting an equilibration of Tf throughout the early endosomal system by this retrograde pathway. This retrograde traffic may be important for delivering molecules from the recycling compartment, which is a long-lived organelle, to sorting endosomes, which are transient.

Quantification of low density lipoprotein and transferrin endocytic sorting HEp2 cells using confocal microscopy

Numerous experiments on CHO cells have shown that endosomes are composed of separate vesicular and tubulovesicular compartments, such as the sorting endosome, the recycling compartment, and the late endosome. However, Hopkins et al. (Nature 346, 335–339, 1990) have reported that endosomes in HEp2 human carcinoma cells form an extensive tubular reticulum. To resolve their observations with previous results from CHO and other cells, we examined the sorting and intracellular transport of endocytosed macromolecules in HEp2 cells, using low density lipoprotein (LDL) and transferrin (Tf) to probe the lysosomally directed and recycling pathways, respectively. Fluorescent LDL and Tf were observed with laser scanning confocal microscopy to visualize simultaneously both probes' sorting and subsequent post-sorting behavior in HEp2 cells. Quantifying the 3-dimensional cellular distributions of fluorescent LDL and Tf, after a variety of pulsechase schemes, gave the ligands' trafficking rates. Initially, both ligands appear in the same punctate sorting endosomes, and fingers of Tf start extending from these sorting endosomes. Tf rapidly leaves dual-labeled sorting endosomes (t1/2 approximately 2.5 minutes) and enters a post-sorting recycling compartment from which it is recycled out of the cell (t1/2 approximately 7 minutes). We present both morphological and kinetic data supporting the existence of these two separate compartments along the recycling pathway in HEp2 cells. LDL remains in punctate sorting endosomes that eventually lose the ability to receive newly endocytosed LDL, and mature into late endosomes. The trafficking and sorting of Tf and LDL in HEp2 cells follow the same general scheme as in CHO cells, indicating that the tubular endosomes previously seen may be the tubular parts of the sorting endosomes and recycling compartments in these cells. We propose that the endosomes in the recycling pathway of HEp2 cells, as in CHO cells, are composed of short-lived sorting endosomes, accessible to both Tf and LDL, and long-lived post-sorting recycling compartments, which contain Tf and recycling receptors but not LDL.

Automated detection and tracking of individual and clustered cell surface low density lipoprotein receptor molecules

We have developed a technique to detect, recognize, and track each individual low density lipoprotein receptor (LDL-R) molecule and small receptor clusters on the surface of human skin fibroblasts. Molecular recognition and high precision (30 nm) simultaneous automatic tracking of all of the individual receptors in the cell surface population utilize quantitative time-lapse low light level digital video fluorescence microscopy analyzed by purpose-designed algorithms executed on an image processing work station. The LDL-Rs are labeled with the biologically active, fluorescent LDL derivative dil-LDL. Individual LDL-Rs and unresolved small clusters are identified by measuring the fluorescence power radiated by the sub-resolution fluorescent spots in the image; identification of single particles is ascertained by four independent techniques. An automated tracking routine was developed to track simultaneously, and without user intervention, a multitude of fluorescent particles through a sequence of hundreds of time-lapse image frames. The limitations on tracking precision were found to depend on the signal-to-noise ratio of the tracked particle image and mechanical drift of the microscope system. We describe the methods involved in (i) time-lapse acquisition of the low-light level images, (ii) simultaneous automated tracking of the fluorescent diffraction limited punctate images, (iii) localizing particles with high precision and limitations, and (iv) detecting and identifying single and clustered LDL-Rs. These methods are generally applicable and provide a powerful tool to visualize and measure dynamics and interactions of individual integral membrane proteins on living cell surfaces.

Fine needle aspiration cytology of cervical lymphadenopathy with special reference to tuberculosis

One hundred eighty cases of cervical lymphadenopathy have been studied by fine needle aspiration cytological examination followed by histopathologic examination of the excised lymph nodes. The diagnostic accuracy was 84.4% for tuberculous lymphadenitis by fine needle aspiration cytological examination. Observation of caseous necrosis (84.2%) and epithelioid cells (73.6%) were the most characteristic diagnostic features in the aspirated smears. Acid-fast bacilli were observed in 45.6% cases. Metastatic carcinoma also yielded a high diagnostic accuracy ie, 89%. Fine needle aspiration cytology has been found to be safe, quick, inexpensive with high diagnostic accuracy in cervical lymphadenopathy.

Malignant lymphoma--a 15-year study report

Analysis of incidence of different types of malignancies during 15 years showed occurrence of malignant lymphoma in 192 cases (4.1%). There were 82 cases (42.7%) of non-Hodgkin's lymphoma and 110 cases (57.3%) of Hodgkin's disease. Lymphocytic lymphoma, the major type observed among the non-Hodgkin's lymphoma with 58 cases (30.21%), showed a preponderance of well differentiated type (40 cases). Other cases in this group comprised mixed cellularity (2.08%), histiocytic (3.64%) and unclassified one (6.77%). Analysis of the Hodgkin's disease cases showed majority in it belonged to the mixed cellularity type (44.5%) followed by the lymphocytic predominant type (27.3%), lymphocytic depletion type (18.2%) and nodular sclerosing type (10%). The incidence of 14 cases of extranodal lymphomas was 7.3% among the lymphomas with maximum occurrence in the gastrointestinal tract (42.8%).

Sclerema neonatorum--histopathologic study

Histopathological study of 10 cases sclerema neonatorum showed subcutaneous fibrosis with lobulation in all the cases. 8 (80 percent) cases showed non-specific chronic inflammation of dermis and thinning of epidermis with atrophy of rete pegs and hypercollgenisation of dermis was evident in 70 percent cases. Fat necrosis with crystallisation of fat content was not a conspicuous feature.

Rare variant of acute promyelocytic leukaemia

Acute promyelocytic leukaemia (APL) is a peculiar sub-type of acute myeloblastic leukaemia characterised by presence of atypical promyelocytes in bone marrow and peripheral blood and common occurrence of haemorrhagic episodes associated with disseminated intravascular coagulation. Two morphological forms of APL are recognised--typical hypergranular and microgranular or M3 variant. This microgranular form of APL is rare but has got some peculiar features and often can be diagnosed by peripheral blood smear examination alone without bone marrow examination. Three cases of microgranular form of APL observed during a period of 6 months are reported here.