Artesunate induced morphological and mechanical changes of Jurkat cell studied by AFM

In this study, we have used atomic force microscopy (AFM) to study the morphology and mechanical property changes of Jurkat cells exposed to different concentrations of Artesunate (ART) for 24 h at single cellular level. Cell viability and proliferation assays were performed by using the Cell Counting Kit‐8. The concentration of ART, which resulted in the inhibition rate >50% was selected. The AFM images revealed that the cell membrane changed and the ultrastructure also became complex. Mechanical properties of individual cell were tracked with AFM‐based force spectroscopy. The force curves revealed that when a cell was exposed to the ART, the mechanical properties changed obviously. Treated cells had a lower adhesion force of 416.8±37.9 pN, whereas control group had a higher adhesion force of 1064.2±97.0 pN. The Young's modulus decreased to nearly one‐third, from control group of 0.648±0.037 kPa to treated group of 0.254±0.035 kPa and the stiffness increased to nearly 1.5 times, from control group of 1.231±0.084 mN/m to treated group of 1.917±0.137 mN/m. These results suggest that ART can inhibit the proliferation of Jurkat and induce changes in the morphological structure and mechanical properties of Jurkat cells. The high resolution and high sensitivity of AFM can be used to detect morphological and mechanical properties of cells exposed to ART. The AFM may be developed to be a useful tool for detecting the cell death and evaluating the anti‐carcinogen efficacy against tumor cell. SCANNING 31: 83–89, 2009. © 2009 Wiley Periodicals, Inc.     

AFM detection of mitogen-induced morphological changes in human B lymphocyte

B‐lymphocyte activation plays an important role in humoral immune system, and its process has been studied well in vivo and in vitro. However, the ultrastructure and adhesion property changes remain unclear. In this study, changes in the morphology and mechanical properties of human peripheral blood B lymphocytes were first studied by atomic force microscopy (AFM). B lymphocytes were treated with the mitogen, pokeweed mitogen (PWM), and Staphylococcus aureus Cowan strain I (SAC) for 24 hr. After B lymphocyte is stimulated by the mitogen, the cell height, diameter, and volume are changed in different degree. The ultrastructure of the B lymphocytes membrane obviously displayed proteins gathering, corresponding with larger changes of average roughness and mean height of particles on cell membrane. Meanwhile, we detected the adhesion force of B lymphocytes after being stimulated by PWM and SAC. We found that the treated cells had a higher adhesion force of 304.16 ± 60.30 pN (PWM) and 249.63 ± 58.03 pN (SAC) than that of control group (104.28 ± 21.77 pN). Therefore, our results could provide new information to further understand the B‐lymphocyte activation process and their structure‐function analyses. SCANNING 34: 60–67, 2012. © 2011 Wiley Periodicals, Inc.     

The morphological and biomechanical changes of keratocytes cultured on modified p (HEMA‐MMA) hydrogel studied by AFM

The poor integration with host cornea tissue and the low mechanical properties of pHEMA hydrogel for artificial cornea remains a difficult problem to solve. A modified pHEMA hydrogel, MMA copolymerized and type‐I collagen and bFGF immobilized, was previously prepared in an attempt to solve the problems. In this study, the cytotoxicity of Col/bFGF‐p (HEMA‐MMA) and p (HEMA‐MMA) was studied by cell adhesion assay and atomic force microscopy (AFM). The results of cell adhesion assay show that the attachment of keratocytes on the modified membrane is much higher than that of the unmodified membrane. This indicates that the material after modification have better cell–material interaction. The AFM images reveal that the morphology of keratocytes cultured on different substrate is obviously different. The cell cultured on modified membrane presented a completely elongated and spindle‐shape morphology. The force?distance indicates that the biomechanical of keratocytes changes significantly after culturing on different substrates. The adhesion force (2328±523 pN) and Young's modulus (0.51±0.125 kPa) of the cell cultured on modified membrane are much higher, and the stiffness (0.08±0.022 mN/m) is lower than those of the cell cultured on unmodified membrane. These results show that the cytotoxicity of Col/bFGF‐p (HEMA‐MMA) for keratocytes is much improved. SCANNING 31: 246–252, 2009. © 2010 Wiley Periodicals, Inc.     

人脐静脉内皮细胞形貌与表面粘附力的原子力显微镜表征

目的:探讨原子力显微镜(AFM)在研究人脐静脉内皮细胞(ECV304)表面形貌、超微结构及纳米机械性质等方面的应用,讨论ECV304超微结构和机械性质与其功能的关系。方法:利用AFM对ECV304细胞的表面形貌及生物机械性质进行表征与测量。结果:在AFM下观察到用普通光学显微镜难以观察到的ECV304细胞的独特的形态结构,如细胞骨架、伪足及细胞边缘微丝等。ECV304细胞呈现长梭形、多角形、圆形等多种形态,细胞表面平均粗糙度为320.52±75.98 nm,表面均匀分布微绒毛,细胞周围有铺展的圆盘状物质。力曲线定量分析得出针尖与细胞表面的非特异性粘附力为75±14 pN。结论:通过AFM成像和力曲线测量表明,ECV304细胞呈圆形,多角形,梭形等多种形态,针尖与细胞膜表面问的粘附力比较小,约75±14pN。     

Adhesion,unfolding forces,and molecular elasticity of fibronectin coatings: An atomic force microscopy study

Fibronectin is an extracellular matrix protein that is involved in cell adhesion, growth, migration, differentiation, and wound healing. Fibronectin coatings are currently used in many laboratories for biomedical and biotechnology purposes. In this study we have investigated the adhesion and mechanical properties of fibronectin coatings. The coatings were also used to study the role of the residence time and the influence of the loading rate in nonspecific interactions. The results showed that the adhesion force between silica and fibronectin increased with loading rate delivering similar values for residence times of 1 and 2 s. Further analysis indicated that the distance to the transition state was about 0.5 nm. Moreover, the adhesion force did not vary with the loading rate for contact time of 0 s. The unfolding of fibronectin domains also depended of the Dwell time (no unfolding events were observed for zero residence time). Applied loads of 2 nN were able to stretch the fibronectin layer up to 200 nm and to unfold the three fibronectin domains, which were similar for a Dwell time of 1 and 2 s. However, the unfolding length increased with loading rate: below 2.5 µm s^?1 the obtained lengths matched the value of FN I (13.5 nm), while for higher speeds the measured values corresponded to the lengths of FN II (18 nm) and FN III (27 nm). This investigation has answered and opened new questions about the mechanical stability and function of fibronectin coatings. The results have also raised theoretical questions about the difference between specific and nonspecific interactions to be addressed in future work.     

Capturing the elasticity and morphology of live fibroblast cell cultures during degradation with atomic force microscopy

Atomic force microscopy, in a liquid environment, was used to capture in vitro the morphological and mechanical changes that cultured fibroblasts undergo as time elapses from the completion of the cell culture. Topography images illustrated that initially, the nucleus had a height of 1.18 ± 0.2 μm, and after 48 h it had decreased to 550 ± 60 nm; similarly, the cell membrane exhibited significant shrinkage from 34 ± 4 to 23 ± 2 μm. After each image scan, atomic force microscopy indentation was performed on the centre of the nucleus, to measure the changes in the cell elasticity. Examination of the force‐distance curves indicated that the membrane elastic modulus at the nucleus remained the same within the time frame of 48 h, even though the cell morphology had significantly changed.     

Histometric and histomorphologic comparison of combustion and ambustion using in vivo reflectance‐confocal microscopy

Background: When combustion and ambustion induce a superficial injury, they are summarized as superficial burns, regardless of the underlying cause. Reflectance‐confocal microscopy (RCM) allows noninvasive imaging of the human skin on morphological features. We hypothesized that combustion and ambustion have different histomorphological effects on the human skin. Methods: Superficial burns caused by combustion (CO‐group, five females, three males; aged 26.8 ± 14.2 years) and caused by ambustion (AM‐group, four females, four males; aged 28.1 ± 13.8 years) were evaluated 24 h after injury. The following parameters were obtained using RCM on injured and noninjured (control) site: horny layer thickness, epidermal thickness, granular cell size, basal layer thickness. Results: Compared with the controls (12.8 ± 2.5 μm), horny layer thickness decreased significantly to 10.6 ± 2.1 μm in the CO‐group, whereas it increased significantly to 17.8 ± 2.8 μm in the AM‐group. The epidermal thickness did not differ significantly in CO‐group (47.9 ± 2.1 μm) and AM‐group (49.0 ± 3.1 μm), however, both increased significantly compared with the controls (42.7 ± 1.6 μm). The basal layer thickness increased more in AM‐group (17.0 ± 1.2 μm) compared to CO‐group (15.4 ± 1.1 μm). Both differed significantly compared with their controls (13.9 ± 0.9 μm). The granular cell size increased significantly in both groups ompared to the controls (721 ± 42 μm), however, a significantly higher increase was observed in CO‐group compared to AM‐group (871 ± 55 μm vs. 831 ± 51 μm). Conclusions: RCM evaluates significant histomorphological differences in superficial burns caused by combustion and ambustion. The term “superficial burn” should consider the underlying cause and thus supplemented by the term “combustion” or “ambustion.” Microsc. Res. Tech., 2010. © 2009 Wiley‐Liss, Inc.     

Characterization of Talaromyces islandicus–mediated silver nanoparticles and evaluation of their antibacterial and anticancer potential

The biosynthesized silver nanoparticles (AgNPs) have been reported to possess several therapeutic applications. Silver is one of the important metals known for its bioactive properties not only as macromolecule but also as nanoparticle (NP). The current research focused on the eco-friendly synthesis of Talaromyces islandicus VSGF1(Lab code) –mediated AgNPs. The aqueous culture filtrate of T. islandicus VSGF1 was used as a reducing agent. The formation of AgNPs was confirmed by observing the color change from colorless to colloidal earthy-colored and a sharp absorption peak of ultraviolet–visible (UV-vis) spectroscopy at 400 nm. Fourier-transform infrared spectroscopy revealed the involvement of various functional groups for the formation and stabilization of AgNPs. The structure, size, and shape of mycosynthesized AgNPs were identified by X-ray diffraction (XRD), scanning electron microscopy, and atomic force microscopy (AFM) analysis. The XRD analysis exhibited crystalline nature of NPs whereas AFM analysis revealed the spherical shape of AgNP with average size range between 13 and 66 nm. The antibacterial activity of AgNPs (50 μg/ml) investigated against gram-positive and gram-negative bacteria revealed maximum zone of inhibition (ZOI) against drug-resistant Enterococcus faecalis MTCC439 (18.66 ± 0.57 mm) and Pseudomonas aeruginosa MTCC96 (16 ± 0 mm) followed by Staphylococcus aureus MTCC96 (15.33 ± 0.57 mm), Bacillus subtilis MTCC441 (14.66 ± 0.57 mm), and Escherichia coli MTCC45 (14.66 ± 0.57 mm). Further, the AgNPs evaluated for antitumor activity against human hepatocellular carcinoma (HepG2) cell line exhibited promising result with half-maximal inhibitory concentration (MIC) value at 38.17 μg/ml concentration through MTT (methylthiazolyl tetrazolium assay) assay. Apparently, this is the first report from T. islandicus to the best of our knowledge.     

Functionalized magnetic nanoparticles attenuate cancer cells proliferation: Transmission electron microscopy analysis

The penetration and transportation of nanoparticles (NPs) inside the cancer cells is critical to study. In this article, cancer cells (HCT‐116) were treated with functionalized magnetic NPs for the period of 48 hr and studied their ultrastructure by transmission electron microscopy (TEM). The NPs‐treated cells were prepared by chemical fixation and sliced into electron‐transparent arbitrary sections (200 × 200 μm²) by ultramicrotome. Major events of NPs–cell interaction, such as penetration of NPs, encapsulation of NPs into the intracellular compartments, transportation of NPs, and NPs exit, were examined by TEM to understand the mechanism of cell death. The NPs showed the uniform spherical shape with broad size distribution (100–400 nm), while cells displayed irregular morphology with average diameter ~5 μm. Our results showed the successful penetration of NPs deep into the cell, encapsulation, transportation, and exocytosis. Furthermore, we tested the different concentrations (0, 1.5, 12.5, and 50 μg/ml) of NPs on cancer cells and evaluated the cell viability. Laser confocal microscopy and colorimetric analysis together demonstrated that the cell viability is a dose‐dependent phenomenon, where 50 μg/ml specimen showed the highest killing of cancer cells compared to other dosages.     

Curcumin disturbed cell‐cycle distribution of HepG2 cells via cytoskeletal arrangement

Due to its extensive antitumor activity, curcumin has been focused on by more researchers. But, its antiproliferative mechanisms are still unknown. Here we studied the antiproliferative activity of curcumin in human liver cancer HepG2 cells. In order to analyze the cytotoxic activity and anticancer mechanisms of curcumin, we carried out cytotoxicity tests using 3‐[4,5‐dimethyl‐2‐thiazolyl]‐2,5 diphenyltetrazolium bromide (MTT) assay. The HepG2 cell cycle distribution and the expression of tubulin were detected by flow cytometry. Alterations in morphological and cytoskeletal properties of HepG2 cells were investigated using atomic force microscopy (AFM). Simultaneously, the effects of curcumin on the growth and proliferation of HepG2 cells were also assayed by MTT method. Cells were incubated with different doses of curcumin (0–80 μmol/l) for 24 h, the cell viability decreased from 91.10 ± 3.2% to 10.84 ± 4.0%, and the 50% inhibiting concentration (IC₅₀) was 23.15 ± 0.37 μmol/l. Moreover, flow cytometry quantitatively detected that curcumin treatment resulted in a dose‐dependent accumulation of HepG2 cells in G2/M phase with concomitant losses from G0/G1 phase, so curcumin caused cell‐cycle arrest at G2/M phase. Furthermore, we discovered that curcumin was able to upregulate the expression of tubulin in HepG2 cells. In addition, AFM analysis including cell‐membrane structure and cytoskeleton networks is helpful to explain the relationship between the changes of cells and external pharmacologic stimulation. SCANNING 35: 253‐260, 2013. © 2012 Wiley Periodicals, Inc.     

3D‐quantum interferometer using silicon microring‐embedded gold grating circuit

A 3D (three‐dimensional) quantum interferometer consisting of a silicon microring circuit proposed. The interferometer based on the electron spin cloud projections generated by microring‐embedded gold grating. The electron cloud oscillations result from the excitation of the gold grating at the center of the silicon microring by the dark soliton pulse of 1.50 μm center wavelength. The electron cloud spin‐down, spin‐up automatically formed in the two axes (x, y, respectively) and propagated along the z‐axis. In this proposal, the sensing mechanism of the circuit is manipulated by varying the reflector gold lengths of the sensing arm. The electron cloud spin coupled and changed by changing the gold lengths. The sensitivity measurement of the 3D quantum interferometer for three gold layer lengths of 100 nm, 500 nm, and 1,000 nm is (47.62 nm fs^?1, ±0.4762 fs^?1, ±0.01 nm^?1), (238.10 nm fs^?1, ±0.4762 fs^?1, ±0.002 nm^?1), (476.20 nm fs^?1, ±0.4762 fs^?1, ±0.001 nm^?1), respectively. The used circuit parameters are the real ones that can be fabricated by the currently available technology. Moreover, the silicon micro ring circuit acts as a plasmonic antenna, which can apply for wireless quantum communication. The electron cloud spin projection space–time control can apply for quantum cellular automata.     

Reflectance confocal‐laser‐scanning microscopy in vivo assessments of cigarette‐induced dynamic alterations of cutaneous microcirculation on histomorphological level

Objective: Until now, high resolution reflectance confocal‐laser‐scanning microscopy (CLSM) was used for observation of cutaneous morphology in vivo and in real time. We hypothesized that CLSM also allows observation of dynamic processes of cutaneous microcirculation. Methods: Reflectance CLSM (Vivascope1500; Lucid, Rochester, NY) was performed in 24 young male habitual smokers (23 years, range: 19–26, body mass index 23.9 ± 4.04) with relatively limited cigarette exposure (mean: 3.1 ± 2.4 pack‐years). Eight matched nonsmokers served as controls. The quantitative blood cell flow and the diameter of capillary loops were determined prior (baseline), during, as well as 5 and 10 min after smoking. Results: Baseline value for blood cell flow was 55.50 ± 2.33 cells/min, and decreased over 45% during smoking (30.43 ± 3.76/min; P = 0.02). They were still 22% lower (43.33 ± 2.45/min; P = 0.01) 5 min after smoking and exceeded baseline values 10 min after smoking by 13% (63.00 ± 3.10/min; P > 0.05). The baseline values for capillary loop diameter (9.03 ± 0.22 μm) decreased by 21% (7.18 ± 0.28 μm; P = 0.03) during smoking, remained about 9% (8.23 ± 0.18 μm; P = 0.01) lower 5 min after smoking and exceeded baseline values insignificantly by 4% (9.38 ± 0.28 μm; P > 0.05) 10 min after smoking. There were no significant differences to the controls. Conclusion: Reflectance CLSM enables qualitative and quantitative observation of dynamic processes of cutaneous microcirculation on histomorphological level. Microsc. Res. Tech., 2009. © 2008 Wiley‐Liss, Inc.     

Micromorphology analysis of TiO2 thin films by atomic force microscopy images: The influence of postannealing

This work describes an analysis of titanium dioxide (TiO₂) thin films prepared on silicon substrates by direct current (DC) planar magnetron sputtering system in O₂/Ar atmosphere in correlation with three‐dimensional (3D) surface characterization using atomic force microscopy (AFM). The samples were grown at temperatures 200, 300, and 400°C on silicon substrate using the same deposition time (30 min) and were distributed into four groups: Group I (as‐deposited samples), Group II (samples annealed at 200°C), Group III (samples annealed at 300°C), and Group IV (samples annealed at 400°C). AFM images with a size of 0.95 μm × 0.95 μm were recorded with a scanning resolution of 256 × 256 pixels. Stereometric analysis was carried out on the basis of AFM data, and the surface topography was described according to ISO 25178‐2:2012 and American Society of Mechanical Engineers (ASME) B46.1‐2009 standards. The maximum and minimum root mean square roughnesses were observed in surfaces of Group II (Sq = 7.96 ± 0.1 nm) and Group IV (Sq = 3.87 ± 0.1 nm), respectively.     

AFM Investigation on Ox‐LDL‐Induced Changes in Cell Spreading and Cell‐Surface Adhesion Property of Endothelial Cells

The integrity and adhesion properties of endothelium play vital roles during atherosclerosis. It is well known that oxidized low‐density lipoprotein (Ox‐LDL) influences many physiological activities or mechanical properties of endothelial cells. However, the effects of Ox‐LDL on the integrity and nonspecific adhesion properties of endothelial cells are still unclear. In this study, using the topographical imaging and force measurement functions of atomic force microscopy (AFM), we found that Ox‐LDL can transiently weaken the integrity of endothelium by impairing cell spreading of endothelial cells and decrease the attachment of irrelevant blood cells to endothelium by impairing the nonspecific adhesion property of endothelial cells. The AFM‐based data provide important information for understanding the effects of Ox‐LDL on endothelial cells or during atherogenesis. SCANNING 35: 119‐126, 2013. © 2012 Wiley Periodicals, Inc.     

Three‐dimensional morphometric comparison of normal and apoptotic endothelial cells based on laser scanning confocal microscopy observation

Three‐dimensional (3D) morphometric analysis of cellular and subcellular structures provides an effective method for spatial cell biology. Here, 3D cellular and nuclear morphologies are reconstructed to quantify and compare morphometric differences between normal and apoptotic endothelial cells. Human umbilical vein endothelial cells (HUVECs) are treated with 60 μM H₂O₂ to get apoptotic cell model and then a series of sectional images are acquired from laser scanning confocal microscopy. The 3D cell model containing plasma membrane and cell nucleus is reconstructed and fused utilizing three sequential softwares or packages (Mimics, Geomagic, and VTK). The results reveal that H₂O₂ can induce apoptosis effectively by regulating the activity of apoptosis‐related biomolecules, including pro‐apoptotic factors p53 and Bax, and anti‐apoptotic factor Bcl‐2. Compared with the normal HUVECs, the apoptotic cells exhibit significant 3D morphometric parameters (height, volume and nucleus‐to‐cytoplasm ratio) variation. The present research provides a new perspective on comparative quantitative analysis associated with cell apoptosis and points to the value of LSCM as an objective tool for 3D cell reconstruction. Microsc. Res. Tech. 76:1154–1162, 2013. © 2013 Wiley Periodicals, Inc.     

Substrate influence on cell shape and cell mechanics: HepG2 cells spread on positively charged surfaces

A human hepatoma cell line (HepG2) was cultured on positively and negatively charged polyelectrolytes. Cell/surface adhesion and cell shape evolution were followed with quartz microbalance with dissipation (QCM‐D) and optical microscopy as a function of time, respectively. In particular, substrates coated with poly(ethyleneimine) (PEI) led to fast cell attachment and further spreading, with average maximum frequency Δf = 79 Hz and dissipation ΔD = 40 × 10^?6. On the contrary, no cell spreading was observed on poly(sodium‐4‐styrenesulfonate) (PSS), with Δf = 33 Hz and ΔD = 4.5 × 10^?6. Atomic force microscopy (AFM) was used to investigate the influence of cell shape on its mechanical properties. Considering the cells as an homogenous solid material, the corresponding elastic modulus was estimated using the Hertz model. The elastic modulus was calculated at the central part of the cell, and the average values obtained were 191 ± 14 Pa and 941 ± 58 Pa for cells adsorbed on PSS and PEI, respectively. Thus, different cell–substrate interaction implied different cell mechanical properties reflected in a higher elastic modulus for stronger cell/substrate interaction. The combination of QCM‐D, AFM, and optical microscopy allowed the online study of the cell adhesion process, and the mechanical properties of the adhered cells. Microsc. Res. Tech. 2009. © 2009 Wiley‐Liss, Inc.     

Detection of CD133 (prominin‐1) in a human hepatoblastoma cell line (HuH‐6 clone 5)

We examined CD133 distribution in a human hepatoblastoma cell line (HuH‐6 clone 5). We directly observed the cultured cells on a pressure‐resistant thin film (silicon nitride thin film) in a buffer solution by using the newly developed atmospheric scanning electron microscope (ASEM), which features an open sample dish with a silicon nitride thin film window at its base, through which the scanning electron microscope beam scans samples in solution, from below. The ASEM enabled observation of the ventral cell surface, which could not be observed using standard SEM. However, observation of the dorsal cell surface was difficult with the ASEM. Therefore, we developed a new method to observe the dorsal side of cells by using Aclar® plastic film. In this method, cells are cultured on Aclar plastic film and the dorsal side of cells is in contact with the thin silicon nitride film of the ASEM dish. A preliminary study using the ASEM showed that CD133 was mainly localized in membrane ruffles in the peripheral regions of the cell. Standard transmission electron microscopy and scanning electron microscopy revealed that CD133 was preferentially concentrated in a complex structure comprising filopodia and the leading edge of lamellipodia. We also observed co‐localization of CD133 with F‐actin. An antibody against CD133 decreased cell migration. Methyl‐β‐cyclodextrin treatment decreased cell adhesion as well as lamellipodium and filopodium formation. A decrease in the cholesterol level may perturb CD133 membrane localization. The results suggest that CD133 membrane localization plays a role in tumor cell adhesion and migration. Microsc. Res. Tech. 76:844–852, 2013. © 2013 Wiley Periodicals, Inc.     

Morphometric,quantitative, and three‐dimensional analysis of the heart muscle fibers of old rats: Transmission electron microscopy and high‐resolution scanning electron microscopy methods

This research investigated the morphological, morphometric, and ultrastructural cardiomyocyte characteristics of male Wistar rats at 18 months of age. The animals were euthanized using an overdose of anesthesia (ketamine and xylazine, 150/10 mg/kg) and perfused transcardially, after which samples were collected for light microscopy, transmission electron microscopy, and high‐resolution scanning electron microscopy. The results showed that cardiomyocyte arrangement was disposed parallel between the mitochondria and the A‐, I‐, and H‐bands and their M‐ and Z‐lines from the sarcomere. The sarcomere junction areas had intercalated disks, a specific structure of heart muscle. The ultrastructural analysis revealed several mitochondria of various sizes and shapes intermingled between the blood capillaries and their endothelial cells; some red cells inside vessels are noted. The muscle cell sarcolemma could be observed associated with the described structures. The cardiomyocytes of old rats presented an average sarcomere length of 2.071 ± 0.09 μm, a mitochondrial volume density (Vv) of 0.3383, a mitochondrial average area of 0.537 ± 0.278 μm², a mitochondrial average length of 1.024 ± 0.352 μm, an average mitochondrial cristae thickness of 0.038 ± 0.09 μm and a ratio of mitochondrial greater length/lesser length of 1.929 ± 0.965. Of the observed mitochondrial shapes, 23.4% were rounded, 45.3% were elongated, and 31.1% had irregular profiles. In this study, we analyzed the morphology and morphometry of cardiomyocytes in old rats, focusing on mitochondria. These data are important for researchers who focus the changes in cardiac tissue, especially changes owing to pathologies and drug administration that may or may not be correlated with aging. Microsc. Res. Tech., 2013. © 2012 Wiley Periodicals, Inc.     

Palyno‐anatomical studies of monocot taxa and its taxonomic implications using light and scanning electron microscopy

Palyno‐anatomical study of monocots taxa using Light and Scanning Electron Microscopy (SEM) was first time conducted with a view to evaluating their taxonomic significance. Studied plants were collected from different eco‐climatic zones of Pakistan ranges from tropical, sub‐tropical, and moist habitats. The aim of this study is to use palyno‐anatomical features for the correct identification, systematic comparison, and investigation to elucidate the taxonomic significance of these features, which are useful to taxonomists for identifying monocot taxa. A signification variation was observed in quantitative and qualitative characters by using the standard protocol of light microscopy (LM) and SEM. Epidermal cell length varied from maximum in Allium griffthianum (480 ± 35.9) μm at the adaxial surface to minimum in Canna indica (33.6 ± 8.53) μm on abaxial surface. Maximum exine thickness was observed in Canna indica (4.46) μm and minimum in Allium grifthianum (0.8) μm. Variation was observed in shape and exine ornamentation of the pollen, shape of the epidermal cell, number, size, and type of stomata, guard cell shape, and anticlinal wall pattern. Based on these palyno‐anatomical features a taxonomic key was developed, which help in the discrimination of studied taxa. In conclusion, LM and SEM pollen and epidermal morphology is explanatory, significant, and can be of special interest for the plant taxonomist in the correct identification of monocots taxa.     

Ultrastructural analysis of cell wall of drug resistant and sensitive Mycobacterium tuberculosis isolated from cerebrospinal fluid by transmission electron microscope

Drug‐resistant tuberculosis is being increasingly recognized and is one among the leading cause of death worldwide. Remarkable impermeability of cell wall to antituberculous drugs protects the mycobacteria from drug action. The present study analyzed the cell wall thickness among first‐line drug resistant and sensitive Mycobacterium tuberculosis (Mtb) isolated from cerebrospinal fluid by transmission electron microscopy (TEM). The average thickness of the cell wall of sensitive isolates was 13.60 ± 0.98 nm. The maximum difference (26.48%) in the cell wall thickness was seen among multi‐drug resistant (18.50 ± 1.71 nm) isolates and the least difference (4.14%) was shown by streptomycin‐resistant (14.18 ± 1.38 nm) isolates. The ultrastructural study showed evident differences in the cell wall thickness among sensitive and resistant isolates. Preliminary TEM examination of cells indicates that morphological changes occur in the cell wall which might be attributed to the drug resistance. The thickened wall of Mtb appears to help the bacilli to overcome the action of antituberculous drugs.