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PubMed1987

A conceptual model of cell division in neoplasia.

A model of cell division as it occurs in the neoplastic cell is presented. The two basic features of the model are that firstly cell division is autonomous and secondly it is incomplete because not all of the processes which take place during normal division occur in the disordered division of neoplasia. As a result cellular structures may not be replicated along with the rest of the cell and they are therefore deficient. The deficiency of particular structures is then used to explain certain observations made of neoplastic cells eg. disturbances of metabolism and morphology, heterogeneity of the cell population, malignancy and immortalisation. Oncogenes are then introduced into the model in an attempt to understand their role in the development of cancer.

Cell Division↗
PubMed1987

Growth of Mycoplasma bovis in organ cultures of bovine foetal trachea and comparison with Mycoplasma dispar.

Inoculation of tracheal organ cultures from bovine foetuses with Mycoplasma bovis resulted in a loss of cellular structure of the lamina propria, followed 20-22 days later by lifting and detachment of overlying epithelium. The effect was associated with large numbers of M. bovis, identified by immunoperoxidase labelling and electromicroscopy, infiltrating between the epithelial cells and amassing in the lamina propria, especially in the region of the basement membrane of the epithelium. Ciliary activity was undiminished for up to 18 days following inoculation and little or no cytopathic effect on the ciliated epithelium was seen in spite of the close proximity of large numbers of organisms. In contrast, M. dispar was restricted to the margin of the ciliated epithelium where, as previously reported, it caused pyknosis, sloughing and flattening of the epithelium with consequent loss of ciliary activity. The cytopathology observed for each mycoplasma bore a close similarity to the behaviour of the two mycoplasmas in vivo and it is suggested that the organ culture system may be a useful and relevant system to elucidate the pathogenic mechanisms for each mycoplasma.

Animals↗
PubMed1992

Ca(2+)-dependent mechanisms of cytotoxicity and programmed cell death.

There is increasing evidence that the calcium ion plays a critical role in both toxic cell killing and programmed cell death. Thus, in a variety of experimental systems a perturbation of intracellular Ca2+ homeostasis due to increased Ca2+ influx and/or inhibition of Ca2+ extrusion has been found to be an early event in the development of cell injury. It is clear that sustained increases in intracellular Ca2+ can activate cytotoxic mechanisms which result in perturbations of cellular structure and function. For example, the stimulation of Ca(2+)-dependent proteases can result in a disruption of cytoskeletal organization and the formation of surface protrusions (blebs) and Ca(2+)-mediated phospholipase activation can result in an impairment of mitochondrial function with collapse of membrane potential and cessation of ATP synthesis. The activation of a Ca2+, Mg(2+)-dependent nuclear endonuclease is associated with chromatin cleavage and appears to play a crucial role in programmed cell death (apoptosis) in the immune system and other tissues. There is also recent evidence that this process may be responsible for the immunotoxicity of dioxins and organotin compounds and involved in the killing of adenocarcinoma cells by tumor necrosis factor alpha. Although calcium ions appear to be required for endonuclease activity during apoptosis, this process is also influenced by other factors, e.g. protein kinase C activity, intracellular polyamine and Zn2+ levels, chromatin structure, etc. Thus, the regulation of endonuclease activity under both physiological and toxicological conditions appears to be complex and to involve multiple factors.

Animals↗
PubMed1990

Fatal contractions: ultrastructural and electromechanical changes in outer hair cells following transmembraneous electrical stimulation.

A form of outer hair cell vulnerability was examined as related to cellular structure. Electrically-induced somatic displacements on the order of 500 nm (peak-to-peak) were accompanied by a superimposed slow tonic contraction in cell length. Shortening by as much as 22% of the initial cell length was seen to occur at rates of 100 nm/s. Such changes often resulted in increased detection thresholds as well as a reduction in asymmetry of the frequency-following motile response component. The tonic contractions were non-reversible. Solitary cells were recovered following transmembraneous electrical stimulation in order to examine possible structural changes associated with the contractions. In a number of well-preserved controls, multiple flattened non-fenestrated cisternae were found lining the cytoplasmic compartment. In contrast, cells which underwent tonic shortening invariably possessed fragmented membraneous cisternae resembling those typically seen in whole-organ preparations. The degree of fenestration corresponded to the extent of cell shortening. These findings suggest that the so-called 'fenestrated' subsurface cisternae, previously thought to be a normal anatomical component of the outer hair cell, may be the remnant of a highly organized structure in vivo. The potential role of the cisternal system as a force generating substrate is discussed.

Animals↗
PubMed1991

Monoclonal antibodies to inner ear antigens: I. Antigens expressed by supporting cells of the guinea pig cochlea.

Murine monoclonal antibodies against guinea pig cochlear epithelium were generated with the goal of identifying cochlea-specific antigens and elucidating their function. To compensate for the limited amount of cochlear tissue, intrasplenic immunization was used. Hybridoma supernatants were screened by ELISA for antibody production and for binding to homogenates from cochlea, liver, lung, kidney and brain. Hybrids producing antibody to cochlea were subcloned and tested immunocytochemically against frozen sections and surface preparations of paraformaldehyde-fixed cochlear tissue. KHRI-1, a low titer IgM antibody stained only Hensen cells. KHRI-2, also an IgM antibody, stained tectorial membrane, cells of the spiral limbus, cells bordering the space of Nuel, Hensen cells and the root cells of the spiral prominence. KHRI-3, an IgG1 antibody, stained the phalangeal processes of outer pillar cells and the apical portion of phalangeal processes of Deiters' cells in a distinctive wine goblet pattern on surface preparations. KHRI-3 antibody also reacted with peripheral nerves and pia mater of brain in unfixed frozen sections but the antigenic site was not stable to fixation in contrast to the epitope detected in the cochlea. In Western blots of detergent extracts from cochlea KHRI-3 stained a broad tissue-specific band of Mr 70-75 kDa; a narrower band of Mr 68-70 kDa was identified by KHRI-3 in extracts of tongue and brain. KHRI-1 and KHRI-2 did not detect any proteins in Western blots. The monoclonal antibodies KHRI-1, -2, and -3 which define epitopes expressed by discrete populations of supporting cells in the inner ear should be useful in characterizing the nature and function of cellular structures in the cochlea.

Animals↗
PubMed1991

Investigation of cerebral ischemia using magnetization transfer contrast (MTC) MR imaging.

The effects of cerebral ischemia in rat brain were monitored as a function of time using proton MR imaging. Spin-spin relaxation time (T2), proton density, and magnetization transfer contrast (MTC) were measured by MR imaging at various time intervals during a 1-week period following the induction of ischemic damage. Ischemic injury was characterized by a maximization of both T2 value and MTC appearance at 24 hr postischemic injury. These changes were accompanied by a gradual increase in MR observable water density over the first few days of ischemia. A reduction in the magnetization exchange rate between "free" and "bound" water protons as measured by MTC imaging is at least partially responsible for the elevation in T2 values observed during ischemia, and may accompany breakdown of cellular structure.

Animals↗
PubMedDate not supplied

Absorption of intraarticularly injected horseradish peroxidase in synoviocytes of rat synovial membrane: an ultrastructural-cytochemical study.

The ability of type A and type S synoviocytes to absorb horseradish peroxidase (HRP) and the intracellular fate of this tracer were studied by electron microscopic cytochemistry. Different concentrations of HRP (0.1-5 mg/ml) were injected into the left knee joint of rats and at intervals ranging from 1 min to 24 hr after injection the synovial membrane was fixed and incubated for HRP. Type A synoviocytes showed a striking ability to absorb HRP at low concentrations. At 1 and 5 min after injection reaction product was localized in coated pits and coated vesicles (110 nm) as well as in smooth-walled vesicles, vacuoles, and tubules. At 15 min to 4 hr postinjection the lysosomal system became increasingly loaded with reaction product. At 24 hr after injection reaction product had disappeared. At higher concentrations of HRP similar observations were made in the A cells, but reaction product was still apparent in lysosomes at 24 hr postinjection. With respect to type S synoviocytes no reaction product was detected within these cells at any time interval after injection of low concentrations of HRP. However, at 5 min after injection of higher concentrations of HRP reaction product was localized in smooth vesicles and vacuoles mainly restricted to the large cytoplasmic processes facing the joint cavity. At 30 min to 4 hr postinjection the lysosomal system became progressively more loaded with HRP reaction product. At 24 hr after injection reaction product still remained in the lysosomal system. The present findings that type A and type S synoviocytes showed major differences with respect to endocytic capacity and cellular structures involved in absorption of HRP support the interpretation that the A and S cells represent two distinct types of cells and further suggest that endocytosis in these two types of cells serve different functions.

Animals↗
PubMedDate not supplied

Co-expression of tyrosine hydroxylase messenger RNA 1 and 2 in human ventral mesencephalon revealed by digoxigenin- and biotin-labelled oligodeoxyribonucleotides.

In situ hybridization experiments, using oligodeoxyribonucleotides specific for the two major expressed human tyrosine hydroxylase mRNAs, were performed on human brain sections at the level of the mesencephalon. The specificity of the probes was ascertained by Northern blot experiments carried out with independently in vitro synthesized human tyrosine hydroxylase mRNAs. For in situ hybridization experiments, oligodeoxyribonucleotides were labelled with nucleotides tagged with digoxigenin or biotin molecules. The hybridized oligonucleotides were detected by antibodies coupled with peroxidase and alkaline phosphatase enzymes, which yield, with appropriate substrates, brown and purple products, respectively. The simultaneous detection of the two mRNAs with digoxigeninated and biotinylated probes revealed that these two mRNAs are co-expressed in single cells. The purple product obtained with alkaline phosphatase exhibits a discrete distribution within the dopaminergic cells suggesting these mRNAs are associated with sub-cellular structures. Finally, a heterogeneity in the intensity of the labelling of reactive cells with both probes was visualized as well as the expression of the two mRNA species in neurites.

Aged↗
PubMed1995

Antigenic specificity of lymphocytes isolated from valvular specimens of rheumatic fever patients.

T cell lines were established from both valvular specimens and peripheral blood lymphocytes from seven patients with well documented rheumatic heart disease. These cell lines were stimulated with either PHA or streptococcal antigens. Proliferation assays revealed that both valvular and peripheral blood T cell lines reacted to cell wall (CW) and cell membrane (CM) antigens obtained from rheumatic fever associated group A streptococci and not to nephritogenic strains. None of the cell lines reacted to M protein, myosin or other mammalian cytoskeletal proteins. The unique reactivity of rheumatic fever T cell lines only to cellular structures obtained from rheumatogenic strains suggests that these lines react to epitopes specific for antigens obtained from these strains.

Antigens, Bacterial↗
PubMed1991

Endogenous angiotensin II receptors in Xenopus oocytes and eggs.

Angiotensin II (AII) induced strongly desensitizing oscillatory Cl- inward currents in both follicle-enclosed and collagenase-treated Xenopus oocytes. The AII response was abolished by EGTA and attenuated by pertussis toxin. Treatment of oocytes with collagenase transiently reduced both the ratio of oocytes responsive to AII and the amplitude of AII responses, followed by restoration to original levels in 3-4 days. The response to adrenaline, which is mediated by endogenous beta-adrenoceptors in follicle cells, however, was irreversibly abolished by collagenase treatment. These results suggest that endogenous current-mediating AII receptors in oocytes are coupled with phosphatidylinositol hydrolysis and localized in the oocyte or in a cellular structure distinct from that for endogenous beta-adrenoceptors. Progesterone-matured Xenopus eggs also responded to AII, and this AII-induced depolarization resembled the fertilization potential in the eggs, suggesting a possible role of AII receptors in processes of fertilization or growth of the eggs.

Acetylcholine↗
PubMed1988

Lympho-epithelial thymomas. A retrospective study of 88 resections.

Of 113 lympho-epithelial thymomas retrospectively studied, 56 were epithelial, 20 lymphocytic, 30 mixed and 7 were undefined forms. There were 88 resections (20 stage I, 47 stage II, 13 stage III and 8 stage IV). There were 69 primary resections (followed by radiotherapy in 54 cases) of which 57 were complete and 12 were incomplete. There were 19 secondary resections after radiotherapy: 10 were complete and 9 were incomplete and 25 patients were not operated upon and were treated by radio- and chemotherapy. After primary resection, the actuarial 5-year survival is 64.07% and the 10-year survival is 50.86%. After a secondary resection, the 5 year-survival is 43.74%. After non-surgical treatment, it is 18.67%. After surgery, the prognostic importance of staging is confirmed as more important than the cellular structure. Myasthenic patients are subject to late accidents. Postoperative radiotherapy seems to be justified, but its effect is not statistically significant when resection is complete. Post-radiotherapy surgery is beneficial only in cases of complete resection. The metastatic evolution of thymomas has been underrated and seems to depend upon the local control of the tumour. The use of chemotherapy remains to be defined.

Actuarial Analysis↗
PubMed1990

Photophysical studies of pheophorbide a and pheophytin a. Phosphorescence and photosensitized singlet oxygen luminescence.

The triplet states of pheophorbide a and pheophytin a were studied in several environments by direct measurement of the phosphorescence of the pigments and photosensitized singlet oxygen (1O2) luminescence. The spectra, lifetimes and quantum yields of phosphorescence and the quantum yields of 1O2 generation were determined. These parameters are similar for monomeric molecules of both pigments in all the environments studied. Aggregation of the pigment molecules leads to a strong decrease in the phosphorescence and 1O2 luminescence intensities, which is probably due to a large decrease in the triplet lifetime and triplet quantum yield in the aggregates. The results obtained for pheophorbide a and pheophytin a are compared with those previously reported for chlorophyll alpha. The data suggest that the photodynamic activity of the pigments in living tissues is probably determined by the monomeric pigment molecules formed in hydrophobic cellular structures. Aggregated molecules seem to have a much lower activity.

Chlorophyll↗
PubMed2005

Novel dynamic rheological behavior of individual focal adhesions measured within single cells using electromagnetic pulling cytometry.

The rheology of cells and sub-cellular structures, such as focal adhesions, are important for cell form and function. Here we describe electromagnetic pulling cytometry (EPC), a technique to analyze cell rheology by applying dynamic tensional forces to ligand-coated magnetic microbeads bound to cell surface integrin receptors. EPC utilizes an electromagnetic microneedle that is integrated with a computerized control and image acquisition system and an inverted microscope and CCD camera to monitor bead displacement. Arbitrary force regimens may be defined over a wide range of frequency (DC to 10 Hz) and force (100 pN to 10 nN). With EPC, the viscoelastic creep response of individual focal adhesions was measured over three decades in time using RGD-coated magnetic microbeads bound to integrins that induce local focal adhesion assembly and coupling to the internal cytoskeleton. These data were compared to the power-law-like predictions from the soft glassy model of cell rheology proposed by Fabry et al. Although power-law-like behavior was observed in some focal adhesions, 52% of these structures did not exhibit power-law-like behavior, but instead exhibited either a multi-phase response characterized by abrupt changes in slope or experienced a retraction in the opposite direction to the applied force, especially in response to prolonged force application. These data suggest that while the soft glassy model may provide reasonable estimates for aggregate mechanical behavior of living cells, the rheological behavior of individual focal adhesions may be more heterogeneous and complex than suggested by the soft glassy model. These results are considered in context with the hierarchical nature of cytoskeletal architecture.

Animals↗
PubMed2005

Alcohol and oral cancer.

Alcohol, particularly when associated with tobacco use, has been recognized as an important risk factor for mouth cancer for almost 50 years. Together, they are associated with approximately 75% of upper aerodigestive tract cancers. However, intake of alcohol remains high in many countries. The rising incidence of oral cancer has prompted a revaluation of the role of alcohol (both alone and in partnership with other etiologic agents). In this article, the potential role of alcohol in the development of oral cancer is reviewed. In particular, the effect of alcohol on cellular structure and function is considered by reference to histologic and exfoliative cytologic studies of the oral epithelia. Alcohol may influence the proliferative cells by both intracellular (e.g., endocytosis) and intercellular (permeability) pathways. The carcinogenic exposure of the proliferating stem cells in the basal layer may be regulated through these pathways. Individual variation might help explain why oral cancer arises in some, but not in most, people who smoke and consume excess alcohol. Despite this finding, alcohol is strongly associated with the development of oral cancer and other upper aerodigestive tract cancers. Efforts to reduce this burden on the individual and society must be directed toward patient and professional education and research regarding (genetic) susceptibility.

Alcohol Drinking↗
PubMed2006

Heat fixation of cancer cells ablated with high-intensity-focused ultrasound in patients with breast cancer.

BACKGROUND: High-intensity-focused ultrasound (HIFU) is a noninvasive thermal ablation technique. This study reports the use of histological techniques for the pathological assessment of HIFU effects in patients with breast cancer. METHODS: Twenty-three patients with biopsy-proven breast cancer underwent HIFU treatment for primary breast lesion. Mastectomy was performed on all patients after HIFU. By using histological examinations, the surgical specimens were assessed to explore HIFU effects on breast cancer. RESULTS: Coagulation necrosis of targeted tumors was confirmed by microscopy in 23 patients. Tumor cells presented typical characteristics of coagulation necrosis in the peripheral region of the ablated tumor in all patients. However, in 11 of 23 patients, hematoxylin and eosin staining showed normal cellular structure in the central ablated tumor. By using electronic microscopy and nicotinamide adenine dinucleotide-diaphorase stain, those who had normal-appearing cancer cells were not viable. CONCLUSIONS: HIFU can cause the heat fixation of ablated tumor through thermal effect.

Biomarkers, Tumor↗
PubMed2005

Spermatozoal response to osmotic stress.

The process of sperm cryopreservation imparts on sperm cells the stress of low-temperature and drastic osmotic change. Damage to the cell plasma membrane results in cell injury in a number of cellular structures and associated functions. Studies in the author's laboratory have focused upon the various mechanisms of osmotic and thermal injury including plasma membrane lipid structure, mitochondrial membrane potential, and intracellular signaling. We have determined that cryoinjury to sperm, as for somatic cells, is a multi-factorial event and some of these events are reversible while some are not.

Animals↗
PubMed2006

Energy deficiency in the failing heart: linking increased reactive oxygen species and disruption of oxidative phosphorylation rate.

Heart failure is a complex syndrome of numerous dysfunctional components which converge to cause chronic progressive failure of ventricular contractile function and maintenance of cardiac output demand. The aim of this brief review is to highlight some of the mounting evidence indicating that augmented superoxide, related reactive oxygen species and other free radicals contribute to the oxidative stress evident during the progression of heart failure. While much of the source of increased reactive oxygen species is mitochondrial, there are other intracellular sources, which together are highly reactive with functional and structural cellular lipids and proteins. Bioenergetic defects limiting ATP synthesis in the failing myocardium relate not only to post-translational modification of electron transport respiratory chain proteins but also to perturbation of Krebs Cycle enzyme-dependent synthesis of NADH. Accumulation of pathological levels of lipid peroxides relate to dysfunction in the intrinsic capacity to clear and renew dysfunctional proteins. This review also features key limitations of human heart failure studies and potential clinical therapies that target the elevated oxidative stress that is a hallmark of human heart failure.

Adenosine Triphosphate↗
PubMed2003

Recovery from heat shock injury by activation of Na+-glucose cotransporter in renal epithelial cells.

Exposure of cells or organs to sublethal physical or chemical stresses induces disruption of cellular structures and functions. Here, we examined whether Na(+)-glucose cotransporter (SGLT1) is involved in the recovery from heat shock (HS) injury in porcine renal epithelial LLC-PK(1) cells. Recovery from HS (42 degrees C for 3 h, then 37 degrees C for 12 h) increased SGLT1 activity, assessed by [14C]alpha-methyl glucopyranoside uptake, and a maximal transport rate (V(max)) from 2.4 to 5.9 nmol/mg protein/30 min, but did not alter an apparent affinity constant (K(m)). Protein distribution of SGLT1 in apical membrane fraction was also increased after recovery from HS without changing in total membrane fraction. Membrane integrity assessed by calcein accumulation was decreased by HS, and then returned to basal level. This recovery was inhibited by phloridzin, a potent SGLT1 inhibitor, and nonmetabolizable glucose analogues. Anti-transforming growth factor-beta 1 (TGF-beta 1) antibody inhibited both elevation of SGLT1 distribution in apical membrane and recovery of calcein accumulation induced by HS. Taken together, HS increases in the number of SGLT1 protein in apical membrane mediated via TGF-beta 1 signaling pathway. The increase of glucose uptake is necessary to repair plasma membrane integrity.

Animals↗