Search PubMed⌕ Search

Biomedical subjects

Z Malik

Publications and source records attributed to Z Malik.

At least 91 records · Page 5Linked to original sources
PubMed1988

Hemin dependent morphological maturation and endogenous porphyrin synthesis by K562 leukemic cells.

The alterations in the morphological phenotypes of K562 cells induced by exogenous hemin, and its effect on porphyrin accumulation was analyzed by scanning electron microscopy and flow cytometry. The morphology of the uninduced cells was mainly of microvilli, blebi and ruffle covered cells, while after hemin induction the fraction of the blebi-cells increased and smooth erythroid-like cells appeared. The large variations in cell-volume of the cells were decreased only marginally after hemin treatment. Porphyrin fluorescence revealed a marked accumulation of endogenous porphyrins after induction by hemin.

Flow Cytometry↗
PubMed1988

Relationship between changes in antigen expression and protein synthesis in human melanoma cells after hyperthermia and photodynamic treatment.

Hyperthermia and photoactivated hematoporphyrin derivative induce a dose-dependent reduction in the expression of the p250 surface melanoma-associated antigen on the human FME cell line. Expression of this glycoprotein antigen was quantitated by immunofluorescence flow cytometry based on the monoclonal antibody 9.2.27. Decrease in antigen expression was followed by a transient increase above the level for untreated cells, before normalization occurred about one week after treatment. These treatment-induced changes in antigen expression could partly be explained by changes in protein synthesis. This conclusion was based on the following observations: Hyperthermia and photoactivated hematoporphyrin derivative both inhibited protein synthesis. The latter increased again rapidly to rates above normal until antigen expression reached normal level, whereupon the protein synthesis rate decreased to normal. Inhibition of protein synthesis by cycloheximide 1 day after heating, prevented the recovery of antigen expression, demonstrating that protein synthesis is necessary for resumption of normal antigen expression. The changes in both antigen expression and protein synthesis were dose-dependent, and the magnitude and duration of the changes increased with increasing dose. The time courses of the changes in protein synthesis after two different treatments which both inactivated two logs of cells were almost identical, as were the time courses after two lower heat doses inactivating one log of cells. These similarities were reflected in the changes in antigen expression. At the same time as protein synthesis reached its maximum and antigen expression resumed normal level, an increase in the Golgi apparatus was observed ultrastructurally, indicating an increased synthesis rate and transportation of glycoproteins to the cell surface.

Antigens, Neoplasm↗
PubMed1988

Allergenic properties of the genetic variants A and B of bovine beta-lactoglobulin.

The principal allergen in cow's milk is beta-lactoglobulin (beta-Lg) which is normally found as equal mixtures of the A and B genetic variants in pooled milk. The A and B variants were purified in large amounts and fed to guinea pigs. After 15 days, circulating immunoglobulins IgG1 and IgG2 to the milk proteins were detected, with a somewhat higher response to beta-Lg A than B. Sensitised guinea pigs succumbed to anaphylactic shock when challenged intracardially with either variant. The higher response is likely to be due to amino acid residues found only in the A variant, lying in surface regions of the molecule.

Allergens↗
PubMed1988

Stimulation of Friend erythroleukemic cell cytodifferentiation by 5-amino levulinic acid; porphyrins, cell size, segregation of sialoglycoproteins, and nuclear translocation.

The late events of erythroid differentiation in Friend erythroleukemic cells (FELC), stimulated by 5-amino levulinic acid (5-ALA), were studied. Cultivation of the cells in 5-ALA-enriched media triggered a chain reaction, beginning with an immediate and rapid accumulation of endogenous porphyrins, in particular protoporphyrin and hemin. Incorporation of 14C-ALA was rapid and independent of dimethylsulfoxide (DMSO) induction. In parallel, on the second day of growth, a marked decrease in cell volume was elucidated by flow cytometry. The total protein content was reduced, while Fe uptake and hemoglobin synthesis were increased. The combination of DMSO and 5-ALA produced the most effective induction of the FELC, and the differentiation criteria were the most advanced. The cells exposed to the combined stimulation became loaded with heme and hemoglobin and their generation time was prolonged up to 35 h. Transmission electron microscopy of these treated cells showed a morphological alteration to pearlike cells, associated with a typical nuclear translocation phenomenon and a regional segregation of sialoglycoproteins. An uneven distribution of organelles was revealed; one part of the cell contained numerous ribosomes and the nucleus, while the other part was hemoglobinized, contained mitochondria, and the outer membrane was heavily labeled with ferritin hydrazide, a marker for sialoglycoproteins. The enhanced stimulation of Friend cells by 5-ALA promoted an advanced step of erythroid maturation that has much in common with the late events of normal nuclear extrusion process.

Aminolevulinic Acid↗
PubMed1987

Thymus-derived stromal cell lines.

We derived stromal cell lines from mouse thymus using methods previously established for bone marrow stroma. Two main morphologically distinct groups of cell strains emerged: epithelioid and mixed fibroblast-macrophage. Transmission electron microscopy revealed frequent junctional-complex formations between adjacent cells, a feature that characterized almost all of the thymus stromal lines, but was confined to only one of the five distinct subtypes of cell lines from bone marrow. In contrast to marrow stromal cells, the thymus-derived cell lines were all negative with fat-detecting reagents, had low acid phosphatase and no basic phosphatase activities and were unable to support the in vitro proliferation of myeloid progenitor cells (CFU-gm). Leukemia cell inhibitory activity (LCIA) was detected in one of the thymus stromal cell lines. The differences observed between cell lines derived from the stroma of the thymus and those from bone marrow may relate to the functional specificities of these organs.

Animals↗
PubMed1987

Effects of membrane physical parameters on hematoporphyrin-derivative binding to liposomes: a spectroscopic study.

Physical parameters of membrane bilayers were studied for their effect on the binding of hematoporphyrin derivative (Hpd), which is used as a sensitizer in photodynamic therapy of cancerous tissues. The purpose of this study was to clarify which parameters were relevant, under physiological conditions, to the selectivity of Hpd binding to cancer cells. Fluorescence spectroscopy was used to measure the relative partitioning of the dye between the lipid and aqueous media. Increasing the microviscosity of the liposomes' membranes by various bilayer additives results in a strong reduction of Hpd binding, to an extent independent of the specific additive. The effect of temperature near the physiological value as well as the effect of cross membrane potential are small. Surface potential does not affect the binding constant, indicating that the binding species does not carry a net electric charge.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1987

Biochemical and ultrastructural alterations accompany the anti-proliferative effect of butyrate on melanoma cells.

The effect of sodium butyrate on mouse and human melanoma cell lines was evaluated. Sodium butyrate (0.1-2mM) is shown to reduce the clonogenic potential of several melanoma cell lines. The antiproliferative effect of sodium butyrate is accompanied by a marked increase in the activity of the plasma-membrane bound enzyme gamma-glutamyl transpeptidase. Sodium butyrate treated cells acquire a well developed rough endoplasmic reticulum and accumulate fat droplets. The development of the endoplasmic reticulum is associated with a marked increase in the activity of the enzyme marker NADPH cytochrome c reductase. It is suggested that the phenotypic alterations induced by sodium butyrate may serve as markers for the action of this agent on melanoma cells and other tumours.

Animals↗
PubMed1987

Destruction of erythroleukaemic cells by photoactivation of endogenous porphyrins.

Selective destruction of Friend erythroleukaemic cells (FELC) was potentiated by stimulation of endogenous porphyrin synthesis followed by light sensitization. Endogenous porphyrin biosynthesis in FELC was induced by supplementation of 5-amino levulinic acid (5-ALA) at a concentration of 5 X 10(-4) M. The main accumulated product, after 4 days culture, was uroporphyrin, while after 8 days culture the cells were loaded with protoporphyrin, up to 1.5 micrograms 10(-7) cells. Photoirradiation of the cells for 2 min, accumulating endogenous porphyrins, induced cardinal deformations and cell disintegration in greater than 95% of the cells, as examined by scanning electron microscopy (SEM). The photodynamic destruction effects were dependent on cultivation time with 5-ALA. Flow cytometry analysis showed an immediate expansion of cell volume subsequent to irradiation, presumably a consequence of water influx. Transmission electron microscopy (TEM) of photosensitized cells after different time intervals of culture in 5-ALA medium, revealed initial damage to mitochondria and water influx into the nuclear envelope, after 2 days. After 3-4 days in culture the water influx phenomenon was pronounced, chromatin condensation took place and slight rupture of the outer membrane was detected. Cells photosensitized after 5-6 days of culture were completely disintegrated leaving a nuclear remnant and an enormously swollen nuclear envelope. The culture time dependence of the process, showed an interrelationship between the photodynamic effect and porphyrin accumulation sites in cellular compartments. The study presents a specific method for erythroleukaemic cell inactivation.

Aminolevulinic Acid↗
PubMed1987

The anti-proliferative effect of lithium chloride on melanoma cells and its reversion by myo-inositol.

The effect of LiCl on melanoma cell growth and differentiation was studied in mouse and human melanoma cell lines. LiCl markedly inhibited B16 and HT-144 melanoma cell growth in vitro. Clonogenicity in soft agar of the melanoma cells was also markedly inhibited by LiCl. Pretreatment of B16 mouse melanoma cells with LiCl delayed the appearance of melanoma tumours in syngeneic mice. Growth inhibition of cells was accompanied by morphological and biochemical alterations. LiCl induced cell enlargement and formation of dendrite-like structures. The activity of NADPH cytochrome c reductase, an enzymatic marker of endoplasmic reticulum was significantly (2-3 fold) increased. Addition of myo-inositol to cell cultures partially reversed the anti-proliferative and morphological effects of LiCl on melanoma cells. This finding may suggest that the anti-proliferative effect of LiCl is related to its effect on phosphatidylinositol metabolism.

Animals↗
PubMed1987

Chemical inducers of differentiation, dimethylsulfoxide, butyric acid, and dimethylthiourea, induce selective ultrastructural patterns in B16 melanoma cells.

The morphology and ultrastructure of B16 melanoma cells was examined after treatment of the cells with the chemical inducers of differentiation dimethylsulfoxide (DMSO), butyric acid, and dimethylthiourea (DMTU). The treated B16 melanoma cells seemed to be enlarged and more flattened, and to possess dendrite-like structures as revealed by scanning electron microscopy. The main ultrastructural features, depicted by transmission electron microscopy in DMSO-treated B16 cells were: a marked increase in melanin granules, migration of the melanin granules to the dendrites, and appearance of melanosome aggregates. Butyric acid did not induce melanin biosynthesis; however, it stimulated rough endoplasmic reticulum (RER) formation all over the cytoplasm. The DMTU-treated cells also showed a well developed RER accompanied by early stages of melanosomes and melanin granules. The increase in the endoplasmic reticulum was also reflected by enhancement of NADPH cytochrome c reductase activity, an enzymatic marker of the endoplasmic reticulum. The mitochondria in the DMTU-treated cells were swollen with disrupted cristae. The results indicate that DMSO, butyric acid, and DMTU induce different ultrastructural patterns in B16 melanoma cells. These findings correlate with the biochemical alterations induced in melanoma cells by these agents.

Animals↗
PubMed1986

Oligozoospermia, asthenozoospermia, and sperm abnormalities in ex-addict to heroin, morphine, and hashish.

A 40-year-old male had been addicted to heroin, morphine, hashish, and other narcotics for 12 years. At examination, 2 years after abstinence from drugs, his semen analysis revealed oligozoospermia, asthenozoospermia, and morphologically abnormal spermatozoa such as "round-headed" and "kinked"--sperm with neck abnormalities and immature forms. There was no evidence of other morphological abnormalities or of the presence of morphologically normal sperm. A possible correlation is discussed between the long-lasting drug addiction and morphological sperm abnormality, endocrinological function, karyotype, and immunological status.

Adult↗
PubMed1985

Cultured mouse marrow stromal cell lines. II. Distinct subtypes differing in morphology, collagen types, myelopoietic factors, and leukemic cell growth modulating activities.

A series of stromal cell lines were studied for their growth properties, electron microscopic morphology, cytochemical profile, collagen types, production of myelopoietic factors, and modulation of leukemic cell growth. Three cell types were identified in addition to the previously described macrophages (14M and 14M1) and preadipocytes (14F). MBA-1 cells were found to be fibroblasts by their ability to synthesize collagen types I and III, while the cell line MBA-13 shared properties in common with both fibroblasts and endothelial cells (collagen types I, III, IV, V). The third cell type, represented by the stromal cell line MBA-2, produced mainly collagen types IV and V and exhibited junctional complexes between adjacent cells. All of the cell lines tested produced and secreted a macrophage-colony-stimulating factor, CSF-1. MBA-2 and to a lesser extent, MBA-13, produced an additional activity resistant to anti-CSF-1 antiserum. Trypsin extraction of outer surface components from two clones of the MBA-2 cell line (MBA-2.1 and MBA-2.4) yielded high molecular weight factor(s) that specifically inhibited the growth of a plasmacytoma cell line (MPC-11). Such inhibitory activity was not detected in other stromal cell lines. It is possible that this variability in the nature of stromal cell lines represents corresponding diversity of cell types comprising the hematopoietic microenvironment in vivo.

Animals↗
PubMed1985

Sialyl glycoprotein distribution on the plasma membrane of ejaculated ram spermatozoa.

Localization of sialyl residues on unfixed ejaculated ram sperm membrane using the direct covalent probes of either ferritin hydrazide or latex hydrazide revealed a unique regional distribution on the plasmalemma covering the sperm head only. Three different labelling zones were identified based on the intensity and the nature of the sialyl glycoconjugates: a patchy-like zone which included the plasma membrane overlaying the post-nuclear cap and the convex side of the apical body of the acrosome; highly ordered heavily labelled zones including the plasmalemma adjacent to the concave apical body of the acrosome and to the posterior part of the equatorial acrosomal segment; a paucity-labelling zone which included the plasma membrane underlying the principal acrosomal region and the anterior part of the equatorial acrosomal segment. The possible physiological role of the highly ordered labelled zones is discussed.

Acrosome↗
PubMed1985

Encapsulation and capsular types in isolates of Staphylococcus aureus from different sources and relationship to phage types.

The relationship of capsular types of Staphylococcus aureus to type of infection, carrier state, and phage type was studied in a collection of 477 isolates from 380 infection sites. Capsular polysaccharides were demonstrated by precipitation and agglutination with 11 monospecific antisera. When only one isolate from each infection was considered, 63% were of type 8 and 16% were of type 5. Of all the isolates tested, over 90% were encapsulated. We did not demonstrate any marked difference in the distribution of capsular types between isolates from the blood stream or purulent processes and isolates from healthy carriers or food. Most isolates from bovine mastitis milk had nontypeable capsules. The capsular type seemed stable in culture, and encapsulation had no apparent influence on susceptibility to phages. Of 27 phage-propagating strains maintained via culture transfer on artificial media over many years, 16 (59%) produced capsules. A striking association between certain phage patterns and capsular types was demonstrated.

Antigens, Bacterial↗
PubMed1985

Protective effect of cholesterol on Friend leukemic cells against photosensitization by hematoporphyrin derivative.

The cytotoxic effects of hematoporphyrin derivative (HPD) on Friend erythroleukemic cells were studied. Upon binding of the porphyrin to the cells, the fluorescence spectra was shifted from 613 to 633 nm regarding the main band and from 676 to 667 nm concerning the secondary band. The kinetics of HPD binding was then determined. Maximum binding already occurred at 60 s after exposure of the cells to HPD. It could be demonstrated that the effect of the photoactivated HPD on cell viability was drug, dose, and light fluorescence dependent. Cellular protein synthesis and Friend virus complex release from the cells were equally inhibited by the photodynamic sensitization of the drug, indicating no specific effect on virus maturation. Since cholesterol affects the fluidity of cell membranes, it was important to study the effect of cholesterol enrichment on the photodynamic sensitization by HPD. It was found that, while a 50% reduction in protein synthesis was monitored following treatment with 20 micrograms of HPD per ml and illumination by a 6-milliwatt white light for 60 s, no inhibition was observed following preenrichment of the cells with 0.5, 1, or 2% of cholesterol hemisuccinate. The same trend of cholesterol protection was demonstrated with longer illumination periods up to 10 min. The protective effect of cholesterol hemisuccinate was also seen using scanning electron microscopy. It is thus concluded that the cholesterol hemisuccinate content of Friend erythroleukemic cell membranes is an important factor in regulating the cytotoxicity of photoactivated HPD.

Animals↗
PubMed1984

Cultured mouse marrow cell lines: interactions between fibroblastoid cells and monocytes.

Continuous cell lines were derived from primary cultures of adherent bone marrow cells from SJL/J, BALB/c, C3H/eb, RF, and nude-ICR mice. All these lines readily assumed a pure fibroblastoid appearance with the exception of the BALB/c line (MBA-14), which retained both fibroblastoid and monocytoid cells. This particular line could promote the proliferation of myeloid progenitors (CFU-C) in short-term bone-marrow cultures. The two cell types that composed the MBA-14 cell line were successfully isolated and grown separately; the monocytes as the 14M and 14M1 cell lines and the fibroblastoid cells as the 14F clones. The latter were found to be preadipocytes and accumulated fat in the absence of added hydrocortisone, in medium supplemented with fetal calf serum. Growth of the monocyte lines (14M and 14M1) was dependent upon the mononuclear phagocyte stimulator CSF-1. In the parent MBA-14 cell line the growth of monocytes seemed to depend upon stimulating factor(s) produced by the fibroblastoid cells. The 14M1 monocytes were able to process and degrade antigen as efficiently as primary macrophages. Furthermore, processed antigen produced by 14M1 cells evoked proliferative response by antigen-primed lymph-node cells. In addition to these immunological functions the 14M1 cells were capable of modulating the colony-stimulating activity and degree of adipogenesis exhibited by the fibroblastoid cells. These interactions between monocytes and fibroblastoid cells may constitute part of the mechanism controlling the activity of the hematopoietic microenvironment.

Adipose Tissue↗