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PubMed1975

Studies on chromatin. IV. Evidence for a toroidal shape of chromatin subunits.

Electron microscopy of purified chromatin subunits (v-bodies [17] or nucleosomes [2] revealed a hole or at least a deep indentation in the globular nucleosome. A hole in the nucleosome was visualized using rotatory shadowing with platinum-palladium or more directly, by negative staining with sodium phosphotungstate. The diameter of the hole as measured from negatively stained samples is 10-25 A. The external diameter of the negatively stained nucleosome equals 75 +/- 15 A. Although most of the data are formally compatible with either a hole or a deep indentation in the nucleosome, some views of the particles in the negatively stained samples suggest a hole rather than an indentation. The possible significance of a toroidal structure of the chromatin subunit is discussed in the accompanying paper [3].

Animals↗
PubMed2001

Transmission electron microscopical studies on some haemolymph proteins from the marine polychaete Nereis virens.

The hexagonal bilayer haemoglobin molecule from Nereis virens has been investigated in a comparative study using several different negative stain electron microscopical specimen preparations (i.e. by conventional adsorption to continuous carbon support films, by the negative staining-carbon film technique and by negative staining across the holes of holey carbon support films with air-drying and rapid freezing/cryo-negative staining). The benefits and limitations of these different approaches are indicated, with the overall conclusion that negative staining with ammonium molybdate across holes creates the best possibilities for molecular imaging, and also has the potential for the creation of two-dimensional (2D) crystals/arrays at the fluid-air interface. Of the different negative staining procedures presented, cryo-negative staining reveals the greatest details of N. virens haemoglobin. This is exemplified by the direct visualisation of the central linker-assembly within the haemoglobin molecule, a structural feature less clearly defined by the other negative staining techniques. A discoidal lipoprotein molecule (diameter 30-60nm; thickness ca 8nm) has been detected in N. virens, which represents the first documented account of an annelid haemolymph lipoprotein. The biological implications of this lipoprotein for lipid transport remain to be established. The presence of a low concentration of ferritin molecules in N. virens haemolymph is also shown, assisted by the formation of small 2D ferritin arrays in negatively stained specimens prepared across holes.

Animals↗
PubMed1997

Conformation of Lac repressor tetramer in solution, bound and unbound to operator DNA.

We tested whether the Steitz et al. [(1974) Proc. Natl. Acad. Sci. U.S.A., 71:593-597] model of lactose repressor (LacR) (14 x 6.0 x 4.5 nm) represented the shape of free or operator-bound LacR in solution. The model predicts a 14 nm length for bound LacR. Direct measurement, using Pt-C shadow width standards, was 9.6 +/- 0.2 nm long. Using the Steitz model, we generated a distribution of measurements and converted them into a distribution of shadow widths using gold ball standards. Direct measurement of LacR produced a narrower shadow width distribution with a larger mean size than the Steitz model predicted. Measurement along two orthogonal axes of negatively stained LacR images generated a size distribution, also converted into a shadow width distribution using the gold ball standards. Since the experimental shadow width distribution exactly matched the shadow width distribution derived theoretically from negatively stained LacR, our negative-stained images are representative of LacR's conformation in solution. Approximately 56% of negatively stained LacR had a V-shaped fold around an axis orthogonal to its length, bringing the DNA binding domains of each dimer adjacent. This open end of the V binds single operator DNA. The other 44% of the LacR tetramer is in the extended form with its DNA binding sites at opposite ends. Although the V-shaped conformation has a closed hinge with the dimers associated along a side, the extended open-hinged state remains important since LacR must bind two distant operator sites for full repression. Our measurements predict the normal presence of both conformations in nearly equal amounts, suggesting that both are equally active in repressing the lac operon.

Binding Sites↗
PubMed1996

A comparison of methods for the estimation of retroviral burden.

The presence of retroviral contamination is of vital concern in the manufacture of cell culture-derived biopharmaceuticals. These cell lines usually have A- or C-type retrovirus-like particles which are visible by transmission electron microscopy (TEM) even when infectivity (IF) or reverse transcriptase activity (RTA) cannot be demonstrated. The supernatant of the post-production cell cultures, therefore, also needs to be evaluated by TEM for viral burden. A major question, however, is how to establish a quantitative viral load estimate for the evaluation of a purification process. The FDA recommends that a purification process for viral contaminants remove or inactivate 3-5 logs over the estimated viral burden. Viral particles are difficult to identify and quantify, however, by conventional negative staining. We present a comparison of infectivity assay, reverse transcriptase assay, negative staining, and thin sectioned TEM. These assays were performed on four samples. Ultracentrifuged sediments of cleared cell-culture media were measured, fixed and processed. Thin sections were evaluated by TEM and the number of viral particles estimated by morphometric derived quantification. Retrovirus particles were easily identified and quantified when examined by TEM as compared to negative staining and correlated with the other viral assays (IF, RTA). These results demonstrate that the TEM thin section method was a superior technique to negative staining for estimating viral particle load in cell-culture supernatant. To validate further the plastic embedding with thin sectioning, we evaluated cell culture supernatants (pellets) for retroviral burden at various dilutions, from two cell lines. Morphometric determinations were made of the number of viral particles present per unit volume and compared to results obtained by infectivity assay. Since the morphometric calculation for viral density assumes even distribution of viral particles, we also evaluated and calculated viral counts on multiple thin sections taken throughout selected pellets.

Animals↗
PubMed2005

Clear cell fibrous papule with NKI/C3 expression: clinical and histologic features in six cases.

Fibrous papule of the nose is a common benign lesion of dermal fibroblast lineage. Two unusual variants have been described, namely, fibrous papule with granular cells and fibrous papule with clear fibrocytes. We report a second case series (six cases) of clear cell fibrous papule to add to the first series of 9 cases. Clinical and histologic features in our cases are similar to those in the first series. All of our specimens were dome-shaped, 2- to 5-mm skin-colored to slightly erythematous papules on the faces of three male and three female adults ranging from 18 to 48 years of age. All but one lesion were on the nose. Clinical differential diagnoses included fibrous papule, verruca, basal cell carcinoma, and a variety of other neoplasms. Histologically, dermal aggregates of clear cells with finely granular to vacuolated cytoplasm, and centrally located nuclei, were found. Most specimens also contained ectatic capillaries, and all showed evidence of irritation or trauma. Periodic acid-Schiff stain was negative in all specimens to which it was applied (5/6). Neural, melanocytic, and epithelial origins were eliminated by negative staining with S-100, Mart-1, cytokeratins, epithelial membrane antigen, and carcinoembryonic antigen, performed on some of the specimens. A mesenchymal nature was confirmed in one specimen staining strongly positive for vimentin. Five of six cases stained positively for CD68, and all five cases studied were strongly and diffusely positive for NKI/C3. Factor XIIIa stain highlighted scattered dendritic cells within the lesion but was otherwise negative in all six cases studied. Recognition of this variant of fibrous papule is important to distinguish this benign lesion from other clear cell neoplasms.

Acanthoma↗
PubMed1982

Specificity of stain distribution in electron micrographs of protein molecules contrasted with uranyl acetate.

The mechanism of contrast enhancement of protein molecules by negative staining with uranyl acetate has been investigated by analysing electron micrographs of microcrystals of the human immunoglobulin Dob. Digitally filtered micrographs were compared systematically with idealized reference images which were constructed computationally, starting from knowledge of the primary sequence and three-dimensional crystal structure of this IgG molecule. By separately modelling negative staining as bulk exclusion of heavy metals, and positive staining as the specific decoration of charged amino acid residues, and then combining these simulated images, we were able to assess quantitatively the amount of positive staining present in micrographs of ostensibly 'negatively stained' proteins. At a resolution of 2 nm, we find that the experimental images do indeed exhibit predominantly negative staining, the best matches being obtained by simulations which also include a minor contribution (10-40%) of positive staining. We have also compared two independent measures for the significant resolution present in images of periodic biological specimens: (i) the outermost visible orders of optical diffraction patterns, and (ii) the band-limited resolutions of the idealized simulations when they most closely match the experimental images. These criteria observe close correspondence, thus vindicating the traditional practice of inferring resolution from the optical diffraction spectra of indirectly represented (stained) objects.

Computers↗
PubMed2003

Alpha-methylacyl-CoA racemase: a variably sensitive immunohistochemical marker for the diagnosis of small prostate cancer foci on needle biopsy.

Expression of the alpha-methylacyl-CoA racemase (AMACR) gene has recently been demonstrated by several groups to be markedly elevated in prostate cancer cells with little expression in benign prostate tissue and has been suggested as a molecular marker of prostate cancer on needle biopsy. There is scant data, however, as to the sensitivity and specificity of AMACR in the diagnosis of small foci of cancer on needle biopsy. A total of 209 needle biopsies of the prostate with small foci (<5% of a core) of prostatic adenocarcinoma were identified. A total of 175 cases were received in consultation by one of the authors (140 from a single institution and 35 from different outside institutions) and 34 cases were from our hospital file. Immunohistochemistry for high molecular weight cytokeratin and p63 was performed in all cases to confirm the diagnosis of cancer. Only AMACR staining that was significantly stronger than that of background benign glands was considered positive; 88% of all cases of prostate cancer were positive for AMACR. The sensitivity varied among the different groups: 100% for the in house cases, 87.1% for the cases from a single institution, and 80% for cases from different outside institutions. The mean percentage of stained glands in positive cases was 95.9%, with 150 (71.8%) cases showing 100% of the glands positive and 25 (12.0%) cases showing no staining. Because negative staining for basal cell markers, especially in a small focus of atypical glands, is not necessarily diagnostic of prostate cancer, positive staining for AMACR can increase the level of confidence in establishing a definitive malignant diagnosis. However, the sensitivity of AMACR staining may vary in specimens from different pathology laboratories, possibly related to differences in fixation and processing. It is important to optimize the staining technique for each laboratory and recognize that some small cancers on needle biopsy may be AMACR negative.

Adenocarcinoma↗
PubMed2005

Negative myoglobin staining in hemiplegic muscle of acute stroke patients predicts functional recovery.

OBJECTIVE: There is little information on skeletal muscle changes in patients with acute stroke, despite the repeated observation that levels of serum creatine kinase (CK) and myoglobin (Mb) increase in the initial phase of strokes. It is also not clearly known whether the CK and Mb are derived from skeletal muscle or myocardium. DESIGN: Biceps muscle biopsies of the hemiplegic side were obtained from 157 ischemic stroke patients on the second day of stroke onset and were examined for immunoreactivity to Mb, and measurements of Mb, total CK, troponin T, epinephrine, and norepinephrine were made on the same day. The degree of disability of patients was assessed at 7 days and at 12 mos after stroke using the Barthel index and the Scandinavian Stroke Scale. The control group consisted of 159 healthy volunteers matched in age and sex. RESULTS: Lack of Mb immunoreactivity was observed in 109 patients. The prevalence of negatively stained muscle fibers ranged from 0.0% to 22.0%, with a mean of 5.9% +/- 6.0%. The mean values of serum Mb, CK, troponin T, and norepinephrine were higher in patients than those in the control group (P < 0.0001 for all indices; percentage differences were 658% for Mb, 529% for CK, and 258% for norepinephrine). A positive correlation was observed between the prevalence of negative Mb immunostaining in fibers and the Mb (r2 = 0.968, P < 0.0001), CK (r 2= 0.910, P < 0.0001), and norepinephrine levels (r2 = 0.835, P < 0.0001). During the 12-mo study period, Barthel index and Scandinavian Stroke Scale values improved. The percentage change of the Barthel index and Scandinavian Stroke Scale correlated positively with the prevalence of negative Mb immunostaining in fibers. CONCLUSIONS: It was speculated that ischemia, resulting from vasoconstriction induced by an increase in norepinephrine, may be responsible for the occurrence of fibers with negative immunoreactivity for Mb. Patients with higher negative immunostaining for Mb fibers had poor functional recovery of hemiplegia 12 mos after stroke onset. This implies that these muscular alterations may hamper functional recovery.

Age Factors↗
PubMed1985

Two-dimensional crystals of a membrane protein: arrangement of subunits within the crystal sheet.

Two-dimensional crystals have been prepared from the photosynthetic reaction center of Rhodopseudomonas viridis. Filtered images of these crystals show individual subunits approximately 4.5 nm in diameter arranged at a center-to-center distance of 6.4 nm. Our previous studies suggested that each subunit within such a sheet corresponds to a single photosynthetic reaction center. Air-dried and freeze-etched shadowed preparations of the crystals yield images which are quite different from negatively stained material. Rotary-shadowed surfaces of the crystals show rows of wedge-shaped particles separated by 3 nm furrows. Two such wedge-shaped particles occupy the 12.1 X 12.9 nm area in which four negatively stained subunits are normally visualized. Close analysis of these shadowed pictures suggests that both the shadowed and negatively stained images can be accounted for by a single model of subunit arrangement within the crystal. Within each 12.1 X 12.9 nm unit cell, two subunits are placed near one surface of the sheet, and two others are near the other surface. All four subunits are visible in negative stain. When the surface is shadowed, only the two subunits which project above the surface of the sheet accumulate appreciable amounts of the heavy metal shadow. Because of their close position, one subunit shades the other, forming the wedge-shaped appearance characteristic of the crystal. The only arrangement consistent with both shadowed and negatively stained images is one in which the two raised subunits occupy positions at either end of a diagonal across the unit cell. The analysis of shadowed images indicates that the plane group of the crystals is P22(1)2(1).

Bacterial Proteins↗
PubMed1995

The utility of basal cell-specific anti-cytokeratin antibody (34 beta E12) in the diagnosis of prostate cancer. A review of 228 cases.

Basal cell-specific anti-cytokeratin antibody (34 beta E12) decorates the basal cells of benign prostatic epithelium by standard immunohistochemical techniques, whereas adenocarcinoma of the prostate lacks immunoreactivity with this antibody. We reviewed our experience with this antibody to determine its utility in the diagnosis of adenocarcinoma of the prostate as well as its pattern of usage at a tertiary medical center. In all, 7,242 prostate specimens from 5,262 men were seen at Johns Hopkins Hospital between 1/89 and 4/93. Immunostaining for basal cell-specific cytokeratin (34 beta E12) was originally used for diagnostic purposes in 289 questionable area from 228 cases; 45% of these cases were seen in consultation. The distribution of cases using 34 beta E12 was 52% needle biopsies, 32% transurethral prostatic resections (TURPs). 13% radical prostatectomies, and 3% open enucleations. These procedures constituted 2.8% of all needle biopsies, 7.2% of all TURPs, 1.7% of all radical prostatectomies, and 3.5% of all enucleations seen during this time period. For this study the hematoxylin and eosin stain was reviewed without knowledge of the original diagnosis, a diagnosis was favored, the 34 beta E12 stain was examined, and a final diagnosis was determined. The 34 beta E12 stain established (14%), confirmed (58%), or changed (2%) our favored diagnoses, while 18% remained or became equivocal. The 34 beta E12 stain was of no use in 8% of the cases, yet we felt we were still able to render a final diagnosis even without the help of the stain. The differential diagnoses in the questionable foci using 34 beta E12 were cancer versus focus of atypical glands (44%), adenosis (39%), prostatic intraepithelial neoplasia (PIN) (8%), basal cell hyperplasia (5%), and atrophy (4%). However, 34 beta E12 was used in only 15-20% of all cases of adenosis and basal cell hyperplasia and in < 2% of PIN and atrophy cases seen during this time. Reasons for equivocal results were loss of suspicious glands on cut downs used for staining (49%), too few glands to rely on negative staining (23%), technical problems (15%), limited number of positive staining glands in a small focus (7%), and cautery artifact (6%). Although equivocal cases tended to have fewer negative stained glands than cases diagnosed with cancer, there was no minimum number of negative stained glands required to establish a diagnosis of cancer. From these data we conclude that 34 beta E12 staining is a useful tool in confirming, establishing, or changing the diagnosis in questionable foci seen in the everyday practice of surgical pathology.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenocarcinoma↗
PubMed2004

Glycosyltransferase encoding gene EXTL3 is differentially expressed in the developing and adult mouse cerebral cortex.

Exostosin tumor-like 3 (EXTL3) is a glycosyltransferase involved in heparan sulfate (HS) biosynthesis. HS proteoglycans are critically involved in different steps during brain development. The present in situ hybridization in mice revealed wide EXTL3 expression at different grades in the central and peripheral nervous system components including the neural retina and neural crest-derived structures at embryonic days (E) 11.5, E12.5, E14.5, and E16.5. In the neopallial cortex, an intense EXTL3 expression was observed in the neuroepithelial cells lining the ventricular zone at E11.5 and E12.5. The signal decreased at E14.5 and was further downregulated at E16.5 in the ventricular zone. The pioneer neurons of the preplate at E12.5 differentially expressed the gene. Heavily stained among weakly or negatively stained neurons were observed. At E14.5, the cortical plate cells were moderately and homogeneously stained. In contrast, at E16.5, an upregulated and differential expression pattern was detected. The labeling pattern at E16.5 subdivided the cortical plate cells into a large number of heavily, a moderate number of less intensely, and some negatively stained cell populations. Interestingly, the distinct expression pattern displayed by the three main cell types of the adult cerebral cortex was similar to that of the late corticogenesis stage (E16.5). In the adult, the strongest expression was observed in the pyramidal neurons. The granule-type neurons showed less intense staining while the glia cells were devoid of signals. Our data revealed that EXTL3 expression is developmentally regulated in the mouse nervous system and suggested that it differentially contributes to brain development and corticogenesis.

Animals↗
PubMed1989

A rapid method for staining large chylomicrons.

In this report, we present a rapid method for producing high-quality micrographs suitable for determining the size distributions of particles in concentrated samples of postprandial chylomicrons and chylomicron remnants. The procedure consists of mixing particles with osmium tetroxide in water to stabilize the lipids of the particles. These fixed and positively stained particles are then negatively stained with phosphotungstate in the presence of dilute sucrose. This dual staining procedure prevents the fusion and clustering of chylomicrons during processing for electron microscopy and is effective with particles of different lipid compositions. In addition, this procedure is simple and rapid, adding only one mixing step and 5 min to the preparation time required for conventional negative stains.

Animals↗
PubMed2003

Ca2+ causes release of myosin heads from the thick filament surface on the milliseconds time scale.

We have used electron microscopy to study the structural changes induced when myosin filaments are activated by Ca2+. Negative staining reveals that when Ca2+ binds to the heads of relaxed Ca2+ -regulated myosin filaments, the helically ordered myosin heads become disordered and project further from the filament surface. Cryo-electron microscopy of unstained, frozen-hydrated specimens supports this finding, and shows that disordering is reversible on removal of Ca2+. The structural change is thus a result of Ca2+ binding alone and not an artifact of staining. Comparison of the two techniques suggests that negative staining preserves the structure induced by Ca2+ -binding. We therefore used a time-resolved negative staining technique to determine the time scale of the structural change. Full disordering was observed within 30 ms of Ca2+ addition, and had started to occur within 10 ms, showing that the change occurs on the physiological time scale. Comparison with studies of single heavy meromyosin molecules suggests that an increased mobility of myosin heads induced by Ca2+ binding underlies the changes in filament structure that we observe. We conclude that the loosening of the array of myosin heads that occurs on activation is real and physiological; it may function to make activated myosin heads freer to contact actin filaments during muscle contraction.

Actin Cytoskeleton↗
PubMed1970

A fine structural analysis of intercellular junctions in the mouse liver.

Zonulae occludentes and gap junctions were examined both in the intact mouse liver and in a junction-rich membrane fraction from homogenized mouse liver. These preparations were visualized with the techniques of uranyl acetate staining en bloc, staining with colloidal lanthanum, negative staining with phosphotungstate, and freeze-cleaving. The zonula occludens is arranged as a meshwork of branching and anastomosing threadlike contacts sealing the lumen of the bile canaliculus from the liver intercellular space. The gap junction is characterized in section by a 20 A gap between the apposed junctional membrane outer leaflets, and permeation of this space with lanthanum or phosphotungstate reveals a polygonal lattice of subunits with a center-to-center spacing of 90-100 A. Freeze-cleaved gap junctions show a similar lattice. Extraction of junction-rich fractions with 60% aqueous acetone results in a disappearance of the 20 A gap in sectioned pellets and an inability to demonstrate the polygonal lattice with either the freeze-cleave or negative staining techniques. Extraction of the membranes with 50% acetone does not produce this effect. Thin-layer chromatography of the acetone extracts reveals a group of phospholipids in the 60% extract that are not detectable in the 50% extract. Acetone does not cause any detectable change in the structure of the zonula occludens, but the occluding junction becomes leaky to lanthanum following acetone treatment. The effects of other reagents on the junctions are reported.

Acetates↗
PubMed1994

M-band structure, M-bridge interactions and contraction speed in vertebrate cardiac muscles.

Cardiac muscle M-band structures in several mammals (guinea pig, rabbit, rat and cow) and also from three teleosts (plaice, carp and roach), have been studied using electron microscopy and image processing. Axial structure seen in negatively stained isolated myofibrils or negatively stained cryo-sections shows the presence of five strong M-bridge lines (M6, M4, M1, M4' and M6') except in the case of the teleost M-bands in which the central M-line (M1) is absent, giving a four-line M-band. The M4 (M4') lines are consistently strong in all muscles, supporting the suggestion that bridges at this position are important for the structural integrity of the A-band myosin filament lattice. Across the vertebrate kingdom, cardiac M-band ultrastructure appears to correlate roughly with heartbeat frequency, just as in skeletal muscles it correlates with contraction speed, reinforcing the suggestion that some M-band components may have a significant physiological role. Apart from rat heart, which is relatively fast and has a conventional five-line M-band with M1 and M4 approximately equal, the rabbit, guinea pig and beef heart M-bands from a new 1 + 4 class; M1 is relatively very much stronger than M4. Transverse sections of the teleost (roach) cardiac A-band show a simple lattice arrangement of myosin filaments, just as teleost skeletal muscles. Almost all other vertebrate striated muscles, including mammalian heart muscles, have a statistical superlattice structure. The high degree of filament lattice order in teleost cardiac muscles indicates their potential usefulness for ultrastructural studies. It is shown that, in four-line M-bands in which the central (M1) M-bridges are missing, interactions at M4 (M4') are sufficient to define the different myosin filament orientations in simple lattice and superlattice A-bands. However the presence of M1 bridges may improve the axial order of the A-band.

Actin Cytoskeleton↗
PubMed1992

Immunohistochemical studies on NAP-1/IL-8 in contact eczema and atopic dermatitis.

The neutrophil activating peptide NAP-1/IL-8 has in the past been shown to be secreted by diverse cell-types involved in inflammatory processes. Furthermore, potent biological effects on both neutrophilic granulocytes and lymphocytes enforce its role in inflammation. Recently, immunohistochemical studies using monoclonal anti-NAP-1/IL-8 antibodies have been performed on dermal inflammatory conditions like psoriasis vulgaris. These have demonstrated epidermal IL-8 immunoreactivity in a pattern inversely related to the degree of inflammatory infiltration. Based on these results, in the present study biopsies from patients with contact eczema as well as atopic dermatitis were examined. The same patterns of immunoreactivity were found with either homogeneous epidermal staining, focally negative staining or overall decreased or even absent staining. As in psoriasis, these patterns were related to the degree of inflammatory infiltration. These results prove NAP-1/IL-8 to be involved not only in psoriasis vulgaris, but more likely to be a marker of different inflammatory processes. Future work will have to examine the kinetics as well as stimuli causing these effect.

Biopsy↗
PubMed2005

The significance of tumor markers for proliferation and apoptosis in predicting survival in colorectal cancer.

PURPOSE: Clinicopathologic staging is even today the best prognostic factor in both colon and rectal cancers. There is still considerable variation in survival within the stages. To find other prognostic indicators we investigated six biologic markers associated with apoptosis and cell proliferation. METHODS: Formalin-fixed, paraffin-embedded tissue samples of 363 patients with primary colon or rectal cancer of Dukes Stages A to D were chosen for immunohistochemical staining of five tumor markers: bcl-2, p53, Ki-67, cyclin D1, and carcinoembryonic antigen. Also, the number of apoptotic cells was studied by the terminal deoxynucleotidyl transferase-mediated D: -UTP nick end labeling method in 347 cases. The study was done on specially prepared tissue arrays. RESULTS: In rectal cancer, patients with a Ki-67 labeling index of 5 percent or higher had a better prognosis than those with a lower index. Also, positive cytoplasmic p53 expression predicted a favorable outcome in rectal cancer. In colon cancer, positive nuclear staining of cyclin D1 reflected better survival. Weak and moderate staining of carcinoembryonic antigen correlated with better prognosis than strong staining, but negative staining predicted poor outcome. High apoptotic index of 100 or higher correlated with poor prognosis in colon cancer. However, in rectal cancer, the trend was the opposite. Bcl-2 staining tended to be more intense in samples of patients living 5 years or longer compared with those with worse prognosis. CONCLUSIONS: Colon cancer and rectal cancer seem to have different biologic behavior, at least with respect to apoptosis, cytoplasmic p53 expression, and perhaps Ki-67 and carcinoembryonic antigen. Further studies are needed to clarify the significance of these factors.

Aged↗
PubMed1988

Presence of T-cytotoxic suppressor and leucocyte common antigen positive cells in Alzheimer's disease brain tissue.

Cells expressing leucocyte common antigen (LCA) as well as T-cytotoxic-suppressor (T8) and T-helper-inducer (T4) antigens were detected in significant numbers in the hippocampus and temporal cortex of Alzheimer but not normal brain tissue. Leucocytes and reactive microglia strongly expressed LCA, as well as the class II major histocompatibility complex (MCH) glycoprotein HLA-DR, but astrocytes stained negatively. Such staining indicates the immunocompetent status of microglia, as well as their phenotypic linkage to blood borne mesodermal lines. T8 and T4 positive lymphocytes were detected in capillaries and the surrounding matrix in smaller numbers than LCA positive cells. The MHC class I (HLA-A,B,C) antigens were detected on capillaries in both Alzheimer and control tissue. The significance of LCA, T4 and T8 cells in Alzheimer's disease is unknown but may be indicative of a cell mediated immune response in the disease.

Alzheimer Disease↗