Biomedical subjects

Z Malik

Publications and source records attributed to Z Malik.

At least 37 records · Page 2Linked to original sources

PubMed1999

Spectral morphometric characterization of breast carcinoma cells.

The spectral morphometric characteristics of standard haematoxylin and eosin breast carcinoma specimens were evaluated by light microscopy combined with a spectral imaging system. Light intensity at each wavelength in the range of 450-800 nm was recorded for 10(4) pixels from each field and represented as transmitted light spectra. A library of six characteristic spectra served to scan the cells and reconstruct new images depicting the nuclear area occupied by each spectrum. Fifteen cases of infiltrating ductal carcinoma and six cases of lobular carcinoma were examined; nine of the infiltrating ductal carcinoma and three of the lobular carcinoma showed an in situ component. The spectral morphometric analysis revealed a correlation between specific patterns of spectra and different groups of breast carcinoma cells. The most consistent result was that lobular carcinoma cells of in situ and infiltrating components from all patients showed a similar spectral pattern, whereas ductal carcinoma cells displayed spectral variety. Comparison of the in situ and the infiltrating ductal solid, cribriform and comedo carcinoma cells from the same patient revealed a strong similarity of the spectral elements and their relative distribution in the nucleus. The spectrum designated as number 5 in the library incorporated more than 40% of the nuclear area in 74.08% of the infiltrating lobular cells and in 13.64% of the infiltrating ductal carcinoma cells (P < 0.001). Spectrum number 2 appeared in all infiltrating ductal cells examined and in none of the lobular cells. These results indicate that spectrum number 5 is related to infiltrating lobular carcinoma, whereas spectrum number 2 is characteristic for infiltrating ductal carcinoma cells. Spectral similarity mapping of central necrotic regions of comedo type in situ carcinoma revealed nuclear fragmentation into defined segments composed of highly condensed chromatin. We conclude that the spectral morphometric features found for lobular and ductal cell populations may serve future automated histological diagnostics.

Breast Neoplasms↗

PubMed1999

Photoproduct formation from a zinc benzochlorin iminium salt detected by fluorescence microscopy.

When examined by fluorescence microscopy, tumor cells loaded with a zinc benzochlorin iminium salt showed a very faint deep-red fluorescence that was rapidly transformed to a substantially brighter red-orange fluorescence. Fourier transfer spectroscopy analysis with a red-sensitive detection system revealed that an initial fluorescence at 770 nm was gradually converted to 640 nm fluorescence during excitation. Image analysis showed that photoproduct formation was accompanied by a change in the site of drug localization from the cytoplasm to the nucleus. These studies illustrate the power of interferometry for the characterization of photoproducts and changes in sensitizer localization during photoproduct formation.

Animals↗

PubMed1999

Enhancement of ALA-PDT damage by IR-induced hyperthermia on a colon carcinoma model.

The interaction of photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA) and hyperthermia is not well understood. In the present study, significant enhancement of tumor damage was observed after simultaneous application of ALA-PDT and IR-induced hyperthermia using a broad-band incoherent light source. One hour after systemic administration of ALA at a dose of 200 mg/kg, subcutaneously transplanted C26 colon carcinoma tumors were irradiated with two bands of the VersaLight system, red (R, 580-720 nm) and red plus IR (R + IR, 580-720 nm and 1250-1600 nm). Photoirradiation using the R + IR band at different fluence rates and exposures caused mild heating of the tumor to 39-43 degrees C at a 3 mm depth. Electron microscopy after ALA + R, ALA + R + IR and R + IR treatments showed early mitochondrial swelling that was more pronounced in the ALA + R + IR group. Tumor necrosis assessment, using histology and vital staining, revealed an enhancement of tumor necrosis depth in the ALA + R + IR group compared to ALA + R and R + IR. The results showed that subhyperthermic heating to 39-39.5 degrees C in the ALA + R + IR group decreased the threshold light dose required for 100% tumor necrosis from 210 J/cm2 (observed in the ALA + R group) to 140 J/cm2. A tumor growth delay test, based on tumor volume measurement, also revealed significant enhancement of antitumor effect after application of ALA + R + IR compared to ALA + R.

Aminolevulinic Acid↗

PubMed1998

Herpes simplex virus proteins are damaged following photodynamic inactivation with phthalocyanines.

The photodynamic inactivation of herpes simplex virus type 1 (HSV-1) by two phthalocyanines (Pcs), the cationic dye HOSi-PcOSi(CH3)2(CH2)3N+(CH3)3I-(Pc5) and the amphiphilic dye aluminum dibenzodisulfophthalocyanine hydroxide (AlN2SB2POH), has been compared with that by the anionic dye, Merocyanine 540 (Mc540). Both Pc derivatives demonstrate a remarkable virucidal activity upon light activation even 3 h after the onset of HSV-1 adsorption, while Mc540 is effective for only 30 min after adsorption. Since fusion and virus penetration are promoted by membrane glycoproteins, we have studied the damage to viral proteins following photodynamic treatment (PDT) of HSV-1 and its relation to inactivation. The effect of AlN2SB2POH PDT is assessed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Major changes are found in the protein profile of PDT-treated HSV-1. A reduced ability of specific antibodies to react with HSV-1 major envelope proteins is detected by employing the Western blot assay. In particular, we demonstrate the related changes of glycoprotein D (gD), a structural protein of the HSV envelope. Since the envelope proteins participate in viral entry into the host cell, these alterations to viral envelope proteins may impair their ability to participate in early events of viral entry, leading to reduced infectivity of HSV-1. In contrast, no significant changes in the proteins' electrophoretic mobility could be seen after PDT with Mc540 or with Pc5. When HSV-1 purified proteins are subjected to combined electrophoretic and electro osmotic forces on cellulose acetate, there is a shift in their cathode mobility, which may indicate changes in the protein mass and protein net charges following AlN2SB2POH photosensitization. There are only minor changes in the virus proteins, assayed as above, when HSV-1 is treated with Pc5.

Animals↗

PubMed1998

Spectrally resolved morphometry of the nucleus in hepatocytes stained by four histological methods.

A novel concept of spectrally resolved morphometry for histological specimens was developed using light microscopy combined with spectrally resolved imaging. The spectroscopic characteristics of rat hepatocytes stained by Haematoxylin and Eosin, Romanowsky-Giemsa, periodic acid-Schiff and Masson's trichrome were assessed. Light intensity in the range 450-850 nm was recorded from 10000 pixels of nuclear domains of each stained cell and represented as light transmittance spectra and optical density. In order to identify spectral shifts caused by stain-macromolecule interactions, we compared the spectra of individual stain components with those of DNA and bovine serum albumin. Chromatin and interchromatin areas were classified spectrally using a chosen spectral library followed by morphometric calculations of nuclear domains for each staining method. The spectral fingerprints of Masson's trichrome stain distinguished the nucleolus from the rest of the nuclear chromatin, enabling the demarcation and calculation of the nucleolar area. Spectrally resolved imaging of human hepatocytes stained by Masson's trichrome stain revealed marked differences between the nucleolar area in normal human hepatocytes compared with hepatocellular carcinoma. Masson's trichrome stain also distinguished the nucleolar area in human breast carcinoma cells and keratinocytes.

Animals↗

PubMed1998

Spectral morphometric characterization of B-CLL cells versus normal small lymphocytes.

Spectral morphometric characterization of typical chronic lymphocytic leukemia (B-CLL) cells vs normal small lymphocytes stained by May-Grunwald-Giemsa was carried out by multipixel spectral imaging. The light intensity (450-850 nm of 10(4) pixels) from nuclear domains of each stained cell was recorded and represented as light transmittance spectra and optical density. Transmitted light spectra of two nuclear domains were determined, one with low-intensity light transmittance (LIT) and the other with high-intensity light transmittance (HIT). A spectral library was constructed using the four transmitted light spectra representing the HIT and LIT domains of the normal human lymphocytes and the LIT and HIT domains of the CLL cells. The spectral library served to scan CLL lymphocytes from 10 cases of CLL and the lymphocytes of 10 healthy individuals. Each spectrally similar domain in the nuclei of the lymphocytes was assigned an arbitrary color. The morphometric analysis of the spectrally classified nuclei showed specific spectral patterns for B-CLL in 92% of the cells. The specific spectral characteristics of each of the two cell populations were also observed by their optical density light absorbance spectra. We propose that spectral morphometric analysis may serve as an additional diagnostic tool for detection of CLL lymphocytes in a hematological specimen.

Cell Nucleus↗

PubMed1998

Spectral imaging for quantitative histology and cytogenetics.

Evaluation of cell morphology by bright field microscopy is the pillar of histopathological diagnosis. The need for quantitative and objective parameters for diagnosis gave rise to the development of morphometric methods. Morphometry combined with spectral imaging provides multi-pixel information from a specimen, which can be used for further image processing and quantitative analysis. The spectroscopic analysis is based on the ability of a stained histological specimen to absorb, reflect, or emit photons in ways characteristic to its interactions with specific dyes. Spectral information obtained from a histological specimen is stored in a cube whose appellate signifies the two spatial dimensions of a flat sample (x and y) and the third dimension, the spectrum, representing the light intensity for every wavelength. By mathematical analysis of the cube database, it is possible to perform the function of spectral-similarity mapping (SSM) which enables the demarcation of areas occupied by the same type of material. Spectral similarity mapping constructs new images of the specimen, revealing areas with similar stain-macromolecule characteristics and enhancing subcellular features. Spectral imaging combined with SSM reveals nuclear organization and identifies specifically the nucleoli domains. Therefore, differentiation stages as well as apoptotic and necrotic conditions are easily quantified. The commercial SpectraCube system was developed for the application of spectral imaging in biology, recording both transmitted light and fluorescence. The SKY technique utilizes the advantages of the SpectraCube for multi probe FISH and chromosome karyotyping, identifying marker chromosomes, detecting subtle chromosome translocations and clarifying complex karyotypes.

Cytogenetics↗

PubMed1998

Spectrally resolved imaging of Cabot rings and Howell-Jolly bodies.

The spectral characteristics of erythropoietic cellular inclusions stained by May-Grunwald Giemsa (MGG) were determined by spectrally resolved imaging. Multipixel spectra were obtained from Cabot rings and Howell-Jolly (HJ) bodies, displaying a range of wavelengths of transmitted light. The spectral characteristics of these inclusions were compared with those of isolated DNA, histones (type II) and arginine-rich histones (type VI), all stained by MGG. Results of single-cell spectroscopy show that the spectra of Cabot rings and HJ bodies share spectral characteristics with the type II and type VI histones. However, no resemblance was found between Cabot rings and DNA spectra. The spectral analysis of heterochromatin displayed a spectral pattern with characteristics of both DNA and histones, while the euchromatin showed a major contribution of the DNA component.

Chromatin↗

PubMed1998

Pentoxifylline inhibits hypoxia-induced upregulation of tumor cell tissue factor and vascular endothelial growth factor.

Tissue factor (TF), the membrane glycoprotein that initiates blood coagulation, is constitutively expressed by many tumor cells and is implicated in peri-tumor fibrin deposition and hypercoagulability in cancer. Upregulation of tumor TF correlates with enhanced metastatic potential. Furthermore, TF has been colocalized with VEGF in breast cancer, specially at sites of early angiogenesis. There are no data on the effect of hypoxia on tumor cell TF expression. Since hypoxia is known to stimulate VEGF production, we studied whether this also induces tumor cell TF expression. Confluent monolayers of A375 melanoma, MCF-7 breast carcinoma and A549 lung carcinoma were cultured in either 95% air, 5% CO2 (normoxic) or 95% N2, 5% CO2 (hypoxic; 25-30 mmHg) for 24 h. Procoagulant activity (PCA) was measured by amidolytic and clotting assays, surface TF antigen by flow cytometry, early apoptosis by annexin V binding and VEGF levels in culture supernatants by ELISA. Hypoxia significantly increased tumor cell PCA in all three cell lines tested and TF antigen on A375 cells was increased four-fold (P <0.05). Pentoxifylline (PTX), a methylxanthine derivative, significantly inhibited the hypoxia-induced increase in PCA as well as VEGF release in all three cell lines tested. In A375 cells, PTX significantly inhibited TF antigen expression by both normoxic and hypoxic cells. Hypoxia induced a slight (5%) but not significant, increase in early apoptosis. Intravenous injection of hypoxic A375 cells into nude rats produced more pronounced thrombocytopenia (n = 5, P <0.01) and more lung metastases (n = 3, P <0.05) compared to normoxic cells. We conclude that hypoxia increases TF expression by malignant cells which enhances tumor cell-platelet binding and hematogenous metastasis. Hypoxia-induced upregulation of TF appears to parallel that of VEGF, although the mechanism remains unclear.

Animals↗

PubMed1997

The kinetics of protoporphyrin fluorescence during ALA-PDT in human malignant skin tumors.

Fluorescence monitoring during photodynamic therapy (PDT) with the use of topical 5-aminolevulinic acid (ALA) was carried out in patients bearing superficial and nodular basal cell carcinomas (BCC), squamous cell carcinomas (SCC) and Kaposi's sarcomas. A new diagnostic-therapeutic system based on an incoherent CW light source was used for fluorescence spectral measurements and imaging. The results showed that photoirradiation reduced ALA-induced protoporphyrin IX (PP) fluorescence in all tumors. The rate of PP photobleaching in superficial BCC and SCC tumors was significantly higher than in large nodular BCC tumors. The results showed that the differences in kinetics of fluorescence reduction could be attributed to the tumor thickness. One hour after photoirradiation with a light dose of 170 J/cm2 a phenomenon of re-appearance and recovery of PP fluorescence was observed in the large deeply penetrating BCC tumors and Kaposi's sarcoma lesions. In such cases an additional light treatment was performed. The results of the study demonstrated that fluorescence monitoring is very appropriate for the definition of an optimal ALA-PDT clinical protocol.

Aminolevulinic Acid↗

PubMed1997

Treatment of viral infections with 5-aminolevulinic acid and light.

BACKGROUND AND OBJECTIVE: When 5-aminolevulinic acid (ALA) is exogenously supplied, protoporphyrin IX (PpIX) is accumulated in various cells and makes them light sensitive. The possibility of using such an approach for the treatment of viral infections was studied in this work. STUDY DESIGN/MATERIALS AND METHODS: ALA was added to cultured cells infected with human immunodeficiency virus (HIV). Accumulation of PpIX in the cells as well as virus infectivity after photodynamic treatment (PDT) were assessed. For in vivo studies, guinea pigs were infected with herpes simplex virus (HSV) and then administered ALA at intervals after infection. The animals were exposed to PDT at the site of infection 3 hours after ALA administration. Clinical observations and virus titration were made daily. For clinical studies, two patients with Molluscum contagiosum and Verrucae vulgares were treated with ALA fortified with an iron chelating agent and dimethylsulfoxide, followed 4 hours later by PDT. RESULTS: Cells that are infected with HIV accumulated PpIX upon addition of ALA in vitro. This accumulation was enhanced approximately two-fold in the presence of an iron chelator. Subsequent exposure to red light PDT drastically reduced the virus titer (> 99% for U1 cells latently infected with HIV). In guinea pigs infected with HSV, subsequent administration of ALA and exposure of the lesions to red light shortened the duration of vesicles' appearance from more than a week to a few days and reduced HSV titer in the lesions by > or = 5 log10. ALA-PDT treated AIDS patient suffering from Molluscum contagiosum or a kidney transplant patient with Verrucae vulgares showed greatly improved clinical symptoms one month after treatment. CONCLUSION: It is concluded that ALA-PDT could be effective in treating certain viral infections, particularly those resulting in warts.

Acquired Immunodeficiency Syndrome↗

PubMed1997

Inhibition of malignant cell proliferation by culture media conditioned by cardiac or skeletal muscle.

The present work is an attempt to explain the high resistance of muscles to cancer development. We used primary cultures of rat skeletal and cardiac muscle, and examined the effect of the supernatant of these cultures (conditioned medium; CM) on proliferation of cancer cells. The results demonstrated that CM inhibited the proliferation of several types of malignant cells by more than 50%, without a significant inhibition on normal cells. Cell cycle analysis revealed that CM increased the number of cells in S and G2 phases, suggesting a cytostatic effect of CM. For defining the biological properties of the factor(s) which are present in the CM, skeletal muscle cultures were grown in chemically defined medium (serum free medium). The concentrated sample was applied to a Sephadex G-50 column and three fractions were obtained. Only one fraction showed inhibitory activity. Four protein bands were observed in this fraction, as revealed by SDS-PAGE. We suggest that some, or all of these proteins are responsible for inhibition of tumor cell replication.

Analysis of Variance↗

PubMed1997

In vivo photodynamic therapy with the new near-IR absorbing water soluble photosensitizer lutetium texaphyrin and a high intensity pulsed light delivery system.

An in vivo fluorescence monitoring and photodynamic therapy (PDT) study was performed using the new photosensitizer lutetium texaphyrin (Lu-Tex). This photosensitizer is water soluble and has the additional advantage of strong absorption near 730 nm. C26 colon carcinoma was transplanted in the foot of BALB/c mice. In vivo fluorescence spectroscopy was applied to study Lu-Tex tissue distribution kinetics. For this purpose, fluorescence intensity both in the foot with the tumor and in the normal foot was measured in vivo by the laser-induced fluorescence (LIF) system. For PDT, both feet of the mice were irradiated simultaneously with the use of a new high intensity pulsed light delivery system, the Photodyne. The results of the LIF measurements showed that the maximal fluorescence intensity ratio between the normal and tumor bearing foot (FIR) was observed 24-48 h after the agent injection. Photoirradiation with doses from 90 to 240 J cm-2 (0.6 J cm-2 per 2 ms pulse, 1 Hz) 24 h after injection of Lu-Tex at a dose of 10 mg kg-1 caused significant tumor necrosis and delay in the tumor growth rate. The antitumor effect was enhanced with increasing light doses. Normal tissue response to PDT with Lu-Tex was determined as the damage index of the normal foot, which was irradiated simultaneously with the tumor bearing foot. The normal tissue response after PDT with Lu-Tex was compared with 5-aminolevulinic acid (ALA) induced protoporphyrin IX (PP), chlorin e6 (Chl) and Photofrin (PII) at the same values of antitumor effect. The results showed that at 50, 80 and 100% inhibition of tumor growth the orders of the values of normal foot damage indexes were as follows: ALA > Lu-Tex > or = PII > Chl, PII > ALA > Lu-Tex > Chl and PII > Lu-Tex > ALA > Chl respectively.

Animals↗

PubMed1997

The effect of pentoxifylline on spontaneous and experimental metastasis of the mouse Neuro2a neuroblastoma.

Pentoxifylline (PTX) has been reported to have both direct and indirect anti-tumor effects in experimental tumor models. We studied the effect of PTX on (1) the proliferation of Neuro2a mouse neuroblastoma cells in vitro and in vivo, (2) spontaneous and experimental metastasis, (3) tumor cell membrane fluidity and (4) adhesion to a fibronectin-coated surface. PTX significantly reduced the proliferation of Neuro2a cells in vitro as determined by DNA measurement (P < 0.01) and total cell count (P < 0.02). In vivo, PTX reduced the growth of subcutaneously transplanted primary tumors in syngeneic A/J mice (P < 0.01; n = 15). All seven animals (100%) receiving intravenous tumor cells developed extensive liver metastasis. In contrast, only 1/11 (9%) of animals pre-treated with oral PTX and injected with PTX-treated cells developed liver metastases. Of five mice receiving PTX-treated cells without oral pretreatment of PTX, two out of five (40%) developed liver metastases. There was a slight, but not significant (P = 0.08) increase in both experimental and spontaneous lung metastases formation in PTX-treated animals. However, tumor nodule formation on the lung surface was inefficient. PTX also increased membrane fluidity of the Neuro2a cells and significantly decreased tumor cell adhesion to fibronectin-coated microtiter wells (P < 0.01). We conclude that PTX has a cytostatic effect on the Neuro2a mouse neuroblastoma and exerts an anti-tumor effect on liver metastases following intravenous administration of neuroblastoma cells. Whether these results are directly related to the changes in membrane properties caused by pentoxifylline remains to be established.

Animals↗

PubMed1997

Characterization of smoking-induced nasopharyngeal lymphoid hyperplasia.

The frequency of smoking-induced nasopharyngeal lymphoid hyperplasia in heavy smokers and its potential clinical implications are still unknown. Precise criteria to differentiate this entity from other types of nasopharyngeal lymphoid hyperplasia are needed. A prospective clinicopathological study of smoking-induced nasopharyngeal lymphoid hyperplasia was conducted in 17 heavy smokers. Ten nonsmoking patients, five of them with chronic sinusitis, three with adult-onset adenoid hypertrophy, and two children with adenoidal hypertrophy served as a control group. Both in smokers and in nonsmokers, lymphocytic infiltration of the mucosa was characterized immunohistochemically as T cells. In smokers, semithin (1 micron) sections revealed deformed and migrating cytotoxic lymphocytes in the nasopharyngeal mucosa. The lymphocytes were attached to epithelial, ciliated, and goblet cells, resulting in cell damage. Transmission electron microscopy of biopsies from smokers revealed emperipolesis, characterized by mucosal invasion and epithelial cell damage by an unusual population of migrating T lymphocytes that penetrate them. These findings confirm a direct effect of smoking on the nasopharyngeal lymphoid tissue, which forms part of the immune system. It is concluded that the diagnostic evaluation and therapeutic approach of heavy smokers with otological and airway symptoms should be based on thorough endoscopic examination of the nasopharynx. When the diagnosis is not clear-cut, selective tele-endoscopic biopsy and electron microscopic examination are recommended. This entity should be added to the list of known clinical manifestations of the smoking habit.

Adenoids↗

PubMed1997

The use of porphyrins for eradication of Staphylococcus aureus in burn wound infections.

The assessment of deuteroporphyrin-hemin complex as an agent for the treatment of burn wounds infected with a multiple-drug resistant strain of Staphylococcus aureus was performed. The effect of the porphyrin on the survival of the infectious bacteria was first assayed in culture, and later tested as well in a burned infected animal model. The addition of deuteroporphyrin and hemin, separately or together (as a complex) to a growing culture of S. aureus was monitored during 8 hours. It was found that deuteroporphyrin alone was strongly bactericidal only after photosensitization. On the other hand, hemin alone was moderately bactericidal but light independent. A combination of both deuteroporphyrin and hemin was extremely potent even in the dark and did not require illumination to eradicate the bacteria. The in vivo experiments by application of the above porphyrins in combination to infected burn wounds in guinea pigs was an effective way to reduce dramatically the contaminating S. aureus. Reduction of more than 99% of the viable bacteria was noted after the porphyrin mixture was dropped on the eschar or injected into the eschar, an effect that lasted for up to 24 hours. The deuteroporphyrin-hemin complex may be suggested as a new bactericidal treatment of S. aureus infected burns since it was found to be a potent and promising anti-Staphylococcal agent.

Administration, Topical↗

PubMed1997

Subcellular localization of sulfonated tetraphenyl porphines in colon carcinoma cells by spectrally resolved imaging.

Subcellular localization of the dye, 5,10,15,20-tetra(4-sulfonatophenyl)porphine (TPPS4) and the more hydrophobic dye, 5,10,15,20-tetra(1-sulfonatophenyl)porphine (TPPS1), in murine colon carcinoma cells was studied by spectrally resolved imaging (SRI) combined with image processing techniques. Spectrally resolved imaging enabled the acquisition of multipixel fluorescence spectra (> 10(4)) from a single cell. Demarcation of specific localization sites and segregation of the irrelevant fluorescence were based on the pixel spectra and by operating the functions of spectral similarity mapping (SSM), principal component analysis (PCA) and spectral classification. The SRI revealed the fine details of the photochemical process that clarify some aspects of subcellular damage. The SRI depicted the differences between TPPS4 and TPPS1 with respect to their initial localization and their fate at the end of the photochemical effect. The dye TPPS4 was localized initially in lysosomal vesicles, and upon irradiation fluorescence was seen in the nucleus as well as in vesicles. Some of the vesicles were closely related to the nucleus, as resolved by SSM, PCA and spectral classification. Additional light exposure stimulated relocalization of TPPS4 into the nucleus as well as into the nucleolus, which was clearly depicted by SSM and PCA. Spectral classification showed a third, weak residual cytoplasmic array around the nucleus. The dye TPPS1 concentrated in a Golgi-like complex and was resolved in the nuclear envelope and in small vesicles: it was not redistributed into other compartments upon photosensitization. Serum supplementation to the incubation media of colon carcinoma cells treated with TPPS4 or TPPS1 did not change the localization patterns. Pixel spectra of the two dyes in the cells showed spectral shifts and expanded shoulders due to microenvironmental effects. Thus, the chemical nature of the sulfonated phenyl porphines, and not their interaction with serum proteins, was the main determinant of their binding to the lysosomes, nucleus, nucleolus, nuclear envelope or Golgi.

Animals↗

PubMed1997

Chromatin condensation in erythropoiesis resolved by multipixel spectral imaging: differentiation versus apoptosis.

Chromatin condensation and nuclear organization of May-Grunwald-Giemsa (MGG)-stained normal erythropoietic bone marrow cells and apoptotic red cell precursors were resolved by spectral bio-imaging. Multipixel spectra were obtained from single cells displaying a range of wavelengths of both transmitted and absorbed light. Two groups of spectra, of low- and high-intensity transmitted light, were revealed in the nuclei of each cell. The absorbance spectra served for the reconstruction of "absorbance images" depicting the affinity of MGG stain for the chromatin of proerythroblasts and of basophilic, polychromatic, and orthochromatic normoblasts. The localization of different spectral components in the nuclei was resolved employing two mathematical methods, spectral similarity mapping and principal component analysis. Novel structures of high symmetry revealing windmill-like organization were detected in basophilic, polychromatic, and orthochromatic normoblast cells. Matching structures were detected in apoptotic normoblasts obtained from an agnogenic myeloid metaplasia patient. Apoptosis was associated with a gradual breakdown of the ordered arrays in the nucleus. We propose that DNA cleavage may lead to fragmentation of the symmetrical windmill-like superstructure of the basic nuclear domains.

Apoptosis↗