Dental Attrition and its Association With the Signs and Symptoms of TMJ Dysfunction and Radiographic Condylar Changes - An Observational Study.

To determine the level of dental attrition and its relation to signs of TMJ dysfunction adding to condylar alterations analyzed by conventional TMJ Tomography and to propose the correlation between dental attrition and signs of TMJ dysfunction and condylar changes. Patients for the study were selected from the regular outpatient Department of Oral Medicine, Diagnosis and Radiology, Rajah Muthiah Dental College and Hospital, Annamalai University, Chidambaram, with performed criteria. The radiographic examination of TMJ is performed by the PLANMECA OPG machine using the tomographic program. Statistical analysis was performed using a Chi-square test to determine the relation between attrition and temporomandidular disorders [TMD] signs and symptoms. The study group comprises 60 subjects who are having dental attrition, and they are divided into three groups according to their age: Group I, 20-40 age; Group II, 41-60 age; Group III, more than 60 age 80% of the samples had one or more tooth with significant attrition with grades of two or more on a 0-4 scale The prevalence of changes in condylar morphology was more in individuals above 40 yrs (33.33%) as compared to those below the age of 40 with a total prevalence of 41.67%. The most common symptom reported is tooth sensitivity, joint sounds, and muscle tenderness. The last reported are scalloped tongue, buccal mucosa ridging, referred pain, and limitation of mouth opening. Out of the 25 subjects who showed condylar changes, 10 subjects had symptoms of TMD. The symptoms reported are strain in the mouth opening, tenderness in jaw movements, and TMJ clicking sounds. Attrition is not a predictable sign of TMJ dysfunction, yet a finite association was defined between attrition and signs and symptoms of TMJ dysfunction. Studies involving larger samples compared with additional radiographic modalities are recommended.

The wake of the triple epidemic (Tripledemic): does it emphasizes the COVID-19 vaccine as a routine immunization for children? - A cross-sectional study.

OBJECTIVE: Many countries, including the USA, are currently confronting a triple epidemic in children as COVID-19 cases increase and new strains emerge which urge COVID-19 vaccination for children. The Advisory Committee on Immunization Practices (ACIP) for the CDC unanimously approved the inclusion of the COVID-19 vaccine (C19V) in the recommended immunizations. As healthcare professionals (HCPs) and parents are significant players in changing the trend of the triple epidemic by giving the C19V, the present study was done to determine awareness and perception of HCPs and parents on the tripledemic and the need for inclusion of C19V in vaccination schedules for children. PATIENTS AND METHODS: A cross-sectional study was conducted among 400 HCPs and 200 parents to assess their knowledge and perception of tripledemic and the need for the inclusion of C19V. RESULTS: Noticeably, half of the participants had either recent personal (36.2%) or family (21.8%) exposure to some of the tripledemic like RSV, Flu, or COVID-19. On perceived awareness, 42% were concerned about tripledemic, and 35% thought that regular C19V may prevent or reduce tripledemic. Ironically, 11% were not willing to give C19V to their children. The logistic regression model for positive perception of tripledemic and regular C19V identified significant relationships with education (OR 2.19, CI 1.48-3.81), gender (OR 0.9, CI 01.02-2.63), recent personal or family exposure to any of the tripledemic (OR 0.239, CI 0.87-1.63) and presence of children in the family (OR 0.71, CI 1.4-1.96). The reason for favorable perception was preventing self and family from tripledemic. CONCLUSIONS: The findings may give insight to the policymakers for a strategic plan to include C19V in the routine schedule to combat the pandemic and tripledemic by improving herd immunity.

Effect of COVID-19 vaccination on influenza-associated respiratory infection (IARI): benefit or backfire.

OBJECTIVE: Undoubtfully, COVID-19 vaccine (C19V) has significantly changed the pandemic's trajectory positively. At the same time, reports of transient local and systemic post-vaccination reactions leave a concern about its unknown impact on common ailments. Its effect on IARI is unclear because the present IARI epidemic began immediately after C19V in the previous season. PATIENTS AND METHODS: A retrospective observational cohort study among 250 Influenza-associated respiratory infection (IARI) patients by a structured interview questionnaire was conducted with the comparison between 3 groups with 1 dose, 2 doses and 2 doses plus booster dose of C19V. The p<0.05 was considered significant in this study. RESULTS: Among samples 21.2% received one dose of the C19V, only 3.6% got Flu vaccination, 30% had ≥2 comorbidities such as diabetes (22.8%), hypertension (28.4%) and ionically, 77.2% were on chronic medications. Significant differences (p<0.05) were found between groups with duration of illness, cough, headache, fatigue, shortness of breath and hospital visits. The logistic regression analysis shows that the extended IARI symptoms and hospital visits were significantly high among Group 3 (OR=9.17, 95% CI=3.01-29.0) and the same trend remained significant after adjusting the incidence of comorbidities among samples, the chronic conditions (OR=5.13, 95% CI=1.37-14.91) and flu vaccination status (O=4.96, 95% CI=1.41-16.2). Also, 66.4% of the patients were indecisive about getting vaccinated further. CONCLUSIONS: It has been challenging to reach any definitive conclusions regarding the effects of C19V on IARI, conducting extensive, substantial population-based studies that integrate clinical and virological data from more than one season is absolutely required, despite the fact that the majority of the reported effects were mild and temporary.

Silver nanoparticles modified ZnO nanocatalysts for effective degradation of ceftiofur sodium under UV-vis light illumination.

Light-induced photocatalytic degradation of ceftiofur sodium (CFS) has been assessed in the presence of plasmonic zinc oxide nanostructures (ZnONSTs), like, ZnO nanoparticles, ZnO nanorods (ZnONRs) and ZnO nanoflowers (ZnONFs). Silver nanoparticles (Ag NPs) loaded ZnO nanostructures (Ag-ZnONSTs) are obtained through seed-assisted chemical reaction followed by chemical reduction of silver. The surface modification of ZnO nanostructures by Ag NPs effectually altered their optical properties. Further, the surface plasmonic effect of Ag NPs facilitates visible light absorption by ZnONSTs and improved the photogenerated electron and hole separation, which makes the ZnONSTs a more active photocatalyst than TiO2 (P25) nanoparticles. Especially, Ag-ZnONRs showed higher CFS oxidation rate constant (k' = 4.6 × 10-4 s-1) when compared to Ag-ZnONFs (k' = 2.8 × 10-4 s-1) and Ag-ZnONPs (k' = 2.5 × 10-4 s-1), owing to their high aspect ratio (60:1). The unidirectional transport of photogenerated charge carriers on the Ag-ZnONRs may be accountable for the observed high photocatalytic oxidation of CFS. The photocatalytic oxidation of CFS mainly proceeds through •OH radicals generated on the Ag-ZnONRs surface under light illumination. In addition, heterogeneous activation of peroxymonosulfate by Ag-ZnONRs accelerates the rate of photocatalytic mineralization of CFS. The quantification of oxidative radicals supports the proposed CFS oxidation mechanism. Stability studies of plasmonic Ag-ZnONSTs strongly suggests that it could be useful to clean large volume of pharmaceutical wastewater under direct solar light irradiation.

Assessment of Effectiveness of Fluconazole and Clotrimazole in Treating Oral Candidiasis Patients: A Comparative Study.

AIMS: One of the most common fungal infections infecting humans is Candidiasis. Belonging to the group of opportunistic infections, it often affects individuals with various debilitating diseases. Fluconazole and clotrimazole are two of the commonly used anti-fungal agents for the treatment of oral candidiasis. Hence, we planned this study to evaluate the effectiveness of fluconazole and clotrimazole in the treatment of patients suffering from candidiasis. MATERIALS AND METHODS: A total of 180 participants were enrolled in the present study. All the patients of candidiasis were divided broadly into two study groups. Group I included patients who were treated with fluconazole mouthrinse whereas group II included patients who were treated with clotrimazole mouth paint. Grading of patient discomfort was done as noted from readings given by the patients. Specimen was collection by a swab from the lesional area of the oral cavity from the patients and were incubated in Sabouraud's dextrose agar medium and assessed. All the patients were treated with medication as give to their respective groups. Patients were recalled as assessed. All the readings were recorded and analyzed. RESULTS: For group I patients, the fungal eradication was 89.5%, whereas for group II patients, the fungal eradication was 86.7%. No significant results were obtained while comparing the mycological eradiation in patients of the two study groups. CONCLUSION: Approximately similar effectiveness in terms of treatment was noted with fluconazole and clotrimazole in treating patients with candidiasis.

Quick, painless, and atraumatic gingival retraction: An overview of advanced materials.

The success of any fixed prosthesis depends on the accuracy of impressions. Finish line exposure has to be adequate during impression making. The goal of gingival retraction is to atraumatically displace gingival tissues to allow access for impression material to record the finish line and provide sufficient thickness of gingival sulcus so that the impression does not tear off during removal. Numerous advanced materials are available for gingival retraction. This article describes the different advanced materials available.

Bone morphogenetic proteins: Signaling periodontal bone regeneration and repair.

Bone morphogenetic proteins (BMPs) are a group of growth factors also known as cytokines and as metabologens. Originally discovered by their ability to induce the formation of bone and cartilage, BMPs are now considered to constitute a group of pivotal morphogenetic signals, orchestrating tissue architecture throughout the body. The important functioning of BMP signals in physiology is emphasized by the multitude of roles for dysregulated BMP signaling in pathological processes. A study done wherein it was found that protein extracts from bone implanted into the animals at nonbone sites induced the formation of new cartilage and bone tissue. This protein extract contained multiple factors that stimulated bone formation and was termed as "BMP." There are at least 15 different BMPs identified to date and are a part of the transforming growth factor-ß super family. The most widely studied BMPs are BMP-2, BMP-3 (osteogenin), BMP-4, and BMP-7 (osteogenic protein-1). Now, any recombination type of morphogenic proteins have been synthesized, for example - recombinant human BMPs.

Comparative evaluation of serum and salivary immunoglobulin G and A levels with total serum protein in oral submucous fibrosis patients: A case control study.

AIM AND OBJECTIVE: The objective of this study is to estimate and compare the serum and salivary immunoglobulin G and A (IgG, IgA) levels in various stages of oral submucous fibrosis (OSMF) patients and relate it to total serum protein (TSP) and hemoglobin (Hb) levels. MATERIALS AND METHODS: The sample for the present study comprised a total of 20 healthy controls, 20 OSMF patients. About 5 ml of blood and 2 ml of saliva were collected. Quantitative analysis of serum and salivary IgG, IgA was done by turbidometric immunoassay. TSP and Hb were estimated by Biuret and cyanmethemoglobin methods, respectively. RESULTS: Serum and salivary IgA and IgG levels were statistically significantly increased (P < 0.001) in OSMF patients when compared to controls. Also serum and salivary IgG and IgA levels showed significantly increased (P < 0.01) in all the three staging of OSMF when compared to control group. Hb levels and TSP levels were significantly decreased (P < 0.001) in OSMF patients when compared to controls. One-way ANOVA, Pearson's correlation, and unpaired t-test were used for statistical analysis. CONCLUSION: The elevated levels of IgG and IgA are also in favor of polygammapathy, which are nonspecific and nondiagnostic objective reflections of an underlying disease. Decreased TSP is a result of host response and Hb, acts as an indicator of nutritional status plays an important role. It is also observed from the present study that the severity of OSMF was directly proportional to the estimated elevated levels of the major IgG and IgA. A need is also felt for the knowledge of immunoprofile estimation in etiology and pathogenesis that would prove a great asset in the proper assessment of this condition.

Gene Microarray Analyses of Daboia russelli russelli Daboiatoxin Treatment of THP-1 Human Macrophages Infected with Burkholderia pseudomallei.

Burkholderia pseudomallei is the causative agent of melioidosis and represents a potential bioterrorism threat. In this study, the transcriptomic responses of B. pseudomallei infection of a human macrophage cell model were investigated using whole-genome microarrays. Gene expression profiles were compared between infected THP-1 human monocytic leukemia cells with or without treatment with Daboia russelli russelli daboiatoxin (DRRDbTx) or ceftazidime (antibiotic control). Microarray analyses of infected and treated cells revealed differential upregulation of various inflammatory genes such as interleukin-1 (IL-1), IL-6, tumor necrosis factor-alpha (TNF-α), cyclooxygenase (COX-2), vascular endothelial growth factor (VEGF), chemokine C-X-C motif ligand 4 (CXCL4), transcription factor p65 (NF-kB); and several genes involved in immune and stress responses, cell cycle, and lipid metabolism. Moreover, following DRR-DbTx treatment of infected cells, there was enhanced expression of the tolllike receptor 2 (TLR-2) mediated signaling pathway involved in recognition and initiation of acute inflammatory responses. Importantly, we observed that highly inflammatory cytokine gene responses were similar in infected cells exposed to DRR-DbTx or ceftazidime after 24 h. Additionally, there were increased transcripts associated with cell death by caspase activation that can promote host tissue injury. In summary, the transcriptional responses during B. pseudomallei infection of macrophages highlight a broad range of innate immune mechanisms that are activated within 24 h post-infection. These data provide insights into the transcriptomic kinetics following DRR-DbTx treatment of human macrophages infected with B. pseudomallei.

Characterization of 1,5-dimethoxynaphthalene by vibrational spectroscopy (FT-IR and FT-Raman) and density functional theory calculations.

In this work, we reported a combined experimental and theoretical study on molecular structure, vibrational spectra and natural bond orbital (NBO) analysis of 1,5-dimethoxynaphthalene. The optimized molecular structure, atomic charges, vibrational frequencies and natural bond orbital analysis of 1,5-dimethoxynaphthalene have been studied by performing DFT/B3LYP/6-31G(d,p) level of theory. The FTIR, FT-Raman spectra were recorded in the region of 4000-400 cm(-1) and 3500-50 cm(-1) respectively. The scaled wavenumbers are compared with the experimental values. The difference between the observed and scaled wavenumber values of the most fundamentals is very small. The formation of hydrogen bond was investigated in terms of the charge density by the NBO analysis. Natural Population Analysis (NPA) was used for charge determination in the title molecule. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis were investigated using theoretical calculations.

Demographic and clinical features of suspected dengue and dengue haemorrhagic fever in the Northern Province of Sri Lanka, a region afflicted by an internal conflict for more than 30 years-a retrospective analysis.

OBJECTIVES: The aim of this study was to determine the demographic, clinical, and notification data of suspected dengue fever (DF) and dengue hemorrhagic fever (DHF) cases admitted to Jaffna Teaching Hospital, Sri Lanka. METHODS: The data were collected from bed head tickets of all patients presenting with clinically suspected DF/DHF from October 2009 to September 2010. RESULTS: A total of 1085 clinically suspected DF/DHF cases were identified, with high numbers occurring during December 2009 to March 2010. The majority of the reported patients were females (n = 550, 50.7%) and approximately three-quarters of the patients (n = 797, 73.5%) were adults. All had fever, but fever spikes were noted in only 129 cases (11.9%; 95% confidence interval (CI) 10.1-13.9%). Over 50% of cases had vomiting (95% CI 47.5-53.5%). Haemorrhages were noted in 266 (24.5%), with gum bleeding in 99 patients (37.2%). Low white blood cell and platelet counts were noted in 27.1% and 85.6% of cases, respectively. Of the 1085 cases, only 24 (2.2%) were screened for dengue IgM/IgG and only 458 cases (42.2%) were notified to the Epidemiology Unit, Ministry of Health, Sri Lanka. CONCLUSIONS: The absence of laboratory diagnosis and poor notification to the Epidemiology Unit were the major drawbacks noted.

Vibrational spectra, NMR and HOMO-LUMO analysis of 9-fluorenone-2-carboxylic acid.

The present work deals with the vibrational spectroscopic studies of 9-fluorenone-2-carboxylic acid (9F2CA) by means of quantum chemical calculations. Comprehensive theoretical and experimental FTIR and FT-Raman spectral analysis of 9F2CA have been carried out by using DFT/B3LYP method with 6-31G(d,p) basis set. The equilibrium molecular geometry, harmonic vibrational frequencies, infrared and Raman intensities of 9F2CA have been calculated. Comparison of the calculated vibrational spectra with the experimental data provides reliable assignments of all observed bands in FTIR and FT-Raman spectra, including in the low frequency region. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by GIAO method and compared with available experimental data. Complete NBO analysis was also carried out to find out the intramolecular electronic interactions and their stabilization energy. Also, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies were found.

Anxiety- rather than depression-like behavior is associated with adult neurogenesis in a female mouse model of higher trait anxiety- and comorbid depression-like behavior.

Adult neurogenesis has been implicated in affective disorders and the action of antidepressants (ADs) although the functional significance of this association is still unclear. The use of animal models closely mimicking human comorbid affective and anxiety disorders seen in the majority of patients should provide relevant novel information. Here, we used a unique genetic mouse model displaying higher trait anxiety (HAB) and comorbid depression-like behavior. We demonstrate that HABs have a lower rate of hippocampal neurogenesis and impaired functional integration of newly born neurons as compared with their normal anxiety/depression-like behavior (NAB) controls. In HABs, chronic treatment with the AD fluoxetine alleviated their higher depression-like behavior and protected them from relapse for 3 but not 7 weeks after discontinuation of the treatment without affecting neurogenesis. Similar to what has been observed in depressed patients, fluoxetine treatment induced anxiogenic-like effects during the early treatment phase in NABs along with a reduction in neurogenesis. On the other hand, treatment with AD drugs with a particularly strong anxiolytic component, namely the neurokinin-1-receptor-antagonist L-822 429 or tianeptine, increased the reduced rate of neurogenesis in HABs up to NAB levels. In addition, challenge-induced hypoactivation of dentate gyrus (DG) neurons in HABs was normalized by all three drugs. Overall, these data suggest that AD-like effects in a psychopathological mouse model are commonly associated with modulation of DG hypoactivity but not neurogenesis, suggesting normalization of hippocampal hypoactivity as a neurobiological marker indicating successful remission. Finally, rather than to higher depression-related behavior, neurogenesis seems to be linked to pathological anxiety.

Molecular structure and vibrational spectra of 3-and 4-amino-2-bromopyridine by density functional methods.

In this work, experimental and theoretical study on the molecular structure and the vibrational spectra of 3-amino-2-bromopyridine (Compound I) and 4-amino-2-bromopyridine (Compound II) are presented. The vibrational frequencies of these compounds were obtained theoretically by DFT/B3LYP employing the 6-311G(2df,2p) basis set for optimized geometries and were compared with Fourier Transform Infrared solid phase spectra (FTIR) in the region of 400-4000 cm(-1), FT-Raman spectra in the region of 100-4000 cm(-1) and with solution phase spectra in the region of 400-4000 cm(-1). Complete vibrational assignment, analysis and correlation of the fundamental modes for these compounds have been carried based on the potential energy distribution (PED). The vibrational harmonic frequencies were scaled using scale factors, yielding a good agreement between the experimentally recorded and the theoretically calculated values. Finally the calculated HOMO and LUMO energies are localized on the entire ring and substituents.

Ageing abolishes the effects of fluoxetine on neurogenesis.

Depression constitutes a widespread condition observed in elderly patients. Recently, it was found that several drugs employed in therapies against depression stimulate hippocampal neurogenesis in young rodents and nonhuman primates. As the rate of neurogenesis is dramatically reduced during ageing, we examined the influences of ageing on neurogenic actions of antidepressants. We tested the impact of fluoxetine, a broadly used antidepressant, on hippocampal neurogenesis in mice of three different age groups (100, 200 and over 400 days of age). Proliferation and survival rate of newly generated cells, as well as the percentage of cells that acquired a neuronal phenotype were analyzed in the hippocampus of mice that received fluoxetine daily in a chronic manner. Surprisingly, the action of fluoxetine on neurogenesis was decreasing as a function of age and was only significant in young animals. Hence, fluoxetine increased survival and the frequency of neuronal marker expression in newly generated cells of the hippocampus in the young adult group (that is 100 days of age) only. No significant effects on neurogenesis could be detected in fluoxetine-treated adult and elderly mice (200 and over 400 days of age). The data indicate that the action of fluoxetine on neurogenesis is highly dependent on the age of the treated individual. Although the function of neurogenesis in the clinical manifestation of depression is currently a matter of speculation, this study clearly shows that the therapeutic effects of antidepressants in elderly patients are not mediated by neurogenesis modulation.

Rapid isolation of monoclonal antibodies. Monitoring enzymes in the phytochelatin synthesis pathway.

Genomics projects have identified thousands of interesting new genes whose protein products need to be examined at the tissue, subcellular, and molecular levels. Furthermore, modern metabolic engineering requires accurate control of expression levels of multiple enzymes in complex pathways. The lack of specific immune reagents for characterization and monitoring of these numerous proteins limits all proteomic and metabolic engineering projects. We describe a rapid method of isolating monoclonal antibodies that required only sequence information from GenBank. We show that large synthetic peptides were highly immunogenic in mice and crude protein extracts were effective sources of antigen, thus eliminating the time-consuming step of purifying the target proteins for antibody production. A case study was made of the three-enzyme pathway for the synthesis of phytochelatins. Enzyme-linked immunosorbent assays and western blots with the recombinant proteins in crude extracts demonstrated that the monoclonal antibodies produced to synthetic peptides were highly specific for the different target proteins, gamma-glutamyl cysteine synthetase, glutathione synthetase, and phytochelatin synthase. Moreover, immunofluorescence localization studies with antibacterial gamma-glutamyl cysteine synthetase and antiglutathione synthetase antibodies demonstrated that these immune reagents reacted strongly with their respective target proteins in chemically fixed cells from transgenic plants. This approach enables research to progress rapidly from the genomic sequence of poorly characterized target genes, to protein-specific antibodies, to functional studies.

One plant actin isovariant, ACT7, is induced by auxin and required for normal callus formation.

During plant growth and development, the phytohormone auxin induces a wide array of changes that include cell division, cell expansion, cell differentiation, and organ initiation. It has been suggested that the actin cytoskeleton plays an active role in the elaboration of these responses by directing specific changes in cell morphology and cytoarchitecture. Here we demonstrate that the promoter and the protein product of one of the Arabidopsis vegetative actin genes, ACT7, are rapidly and strongly induced in response to exogenous auxin in the cultured tissues of Arabidopsis. Homozygous act7-1 mutant plants were slow to produce callus tissue in response to hormones, and the mutant callus contained at least two to three times lower levels of ACT7 protein than did the wild-type callus. On the other hand, a null mutation in ACT2, another vegetative actin gene, did not significantly affect callus formation from leaf or root tissue. Complementation of the act7-1 mutants with the ACT7 genomic sequence restored their ability to produce callus at rates similar to those of wild-type plants, confirming that the ACT7 gene is required for callus formation. Immunolabeling of callus tissue with actin subclass-specific antibodies revealed that the predominant ACT7 is coexpressed with the other actin proteins. We suggest that the coexpression, and probably the copolymerization, of the abundant ACT7 with the other actin isovariants in cultured cells may facilitate isovariant dynamics well suited for cellular responses to external stimuli such as hormones.

Small changes in the regulation of one Arabidopsis profilin isovariant, PRF1, alter seedling development.

Profilin (PRF) is a low-molecular-weight actin binding protein encoded by a diverse gene family in plants. Arabidopsis PRF1 transcripts are moderately well expressed in all vegetative organs. A regulatory mutant in PRF1, prf1-1, was isolated from a library of T-DNA insertions. The insertion disrupted the promoter region of PRF1 100 bp upstream from the transcriptional start site. Although steady state levels of PRF1 transcripts appeared normal in mature prf1-1 plants, the levels in young seedlings were only one-half those observed in wild type. Reactions with a PRF1 isovariant-specific monoclonal antiserum and general anti-profilin antisera demonstrated that PRF1 protein levels also were one-half those found in wild-type seedlings, although total profilin levels were unaffected. Mutant seedlings no longer could downregulate PRF1 levels in the light, as did wild type. Consistent with their molecular phenotypes, young mutant seedlings displayed several morphological phenotypes but developed into apparently normal adult plants. Their initial germination rate and development were slow, and they produced excessive numbers of root hairs. Mutant seedlings had abnormally raised cotyledons, elongated hypocotyls, and elongated cells in the hypocotyl, typical of phenotypes associated with some defects in light and circadian responses. A wild-type PRF1 transgene fully complements the hypocotyl phenotypes in the prf1-1 mutant. The ability of profilin to regulate actin polymerization and participate directly in signal transduction pathways is discussed in light of the prf1-1 phenotypes.

Actin-organelle interaction: association with chloroplast in arabidopsis leaf mesophyll cells.

The role of the cytoskeleton in the regulation of chloroplast motility and positioning has been investigated by studying: (1) structural relationship of actin microfilaments, microtubules, and chloroplasts in cryofixed and freeze-substituted leaf cells of Arabidopsis; and (2) the effects of anti-actin (Latrunculin B; LAT-B) and anti-microtubule (Oryzalin) drugs on intracellular distribution of chloroplasts. Immunolabeling of leaf cells with two plant-actin specific antibodies, which react equivalently with all the expressed Arabidopsis actins, revealed two arrangements of actin microfilaments: longitudinal arrays of thick actin bundles and randomly oriented thin actin filaments that extended from the bundles. Chloroplasts were either aligned along the actin bundles or closely associated with the fine filaments. Baskets of actin microfilaments were also observed around the chloroplasts. The leaf cells labeled with an anti-tubulin antibody showed dense transverse arrays of cortical microtubules that exhibited no apparent association with chloroplasts. The application of LAT-B severely disrupted actin filaments and their association with chloroplasts. In addition, LAT-B induced aberrant aggregation of chloroplasts in the mesophyll and bundle sheath cells. Double labeling of LAT-B treated cells with anti-actin and anti-tubulin antibodies revealed that the microtubules in these cells were unaffected. Moreover, depolymerization of microtubules with Oryzalin did not affect the distribution of chloroplasts. These results provide evidence for the involvement of actin, but not tubulin, in the movement and positioning of chloroplasts in leaf cells. We propose that using motor molecules, some chloroplasts migrate along the actin cables directly, while others are pulled along the cables by the fine actin filaments. The baskets of microfilaments may anchor the chloroplasts during streaming and allow control over proper three-dimensional orientation to light.