Macropinocytosis Research Articles

Low-dose Endothelial Monocyte-activating Polypeptide-II Increases Permeability of Blood–tumor Barrier by Caveolae-mediated Transcellular Pathway

Low-dose endothelial monocyte-activating polypeptide-II (EMAP-II) can selectively increase blood-tumor barrier (BTB) permeability via the paracellular pathway. The role of the transcellular pathway in this process is unclear. This study was conducted to evaluate the potential involvement of the transcellular pathway in EMAP-II-induced opening of the BTB and to identify the associated mechanisms. Evans blue extravasation test was used to measure changes in BTB permeability after EMAP-II (80ng/kg) administration in a rat model of C6 glioma. Changes in the quantity of pinocytotic vesicles in rat brain microvascular endothelial cells (BMECs) were observed using transmission electron microscopy. Reverse transcription-polymerase chain reaction, Western blotting, and immunohistochemistry assays were performed to detect the expression of the caveolar structural proteins, caveolin-1 and caveolin-2, in BMECs. Alterations in the expression of phospho (p)-Src, p-caveolin-1, and p-caveolin-2 and the activity of RhoA also were measured. Effects of tyrosine kinase inhibition on EMAP-II-induced RhoA/Rho kinase activations and tyrosine kinase, RhoA, or Rho kinase inhibition on EMAP-II-induced caveolin-1 and caveolin-2 phosphorylation were determined by inhibition studies. One hour after EMAP-II administration, the quantity of pinocytotic vesicles in BMECs increased markedly, consistent with changes in BTB permeability. The expression levels of caveolin-1, caveolin-2, p-caveolin-1, and p-caveolin-2 in BMECs also were significantly increased at 1h. The peak expression level of p-Src and the peak activity of RhoA occurred at 0.25 and 0.5h, respectively. Inhibition of tyrosine kinase significantly diminished the activities of RhoA and Rho kinase induced by EMAP-II. In addition, EMAP-II-induced phosphorylation of caveolin-1 and caveolin-2 was completely blocked by inhibition of tyrosine kinase, RhoA, or Rho kinase. We suggest that low-dose EMAP-II can induce BTB hyperpermeability via the transcellular pathway, which is associated with phosphorylation and upregulation of caveolin-1 and caveolin-2 and involves the tyrosine kinase/RhoA/Rho kinase signaling pathway.

Real-Time Sensing of Enteropathogenic E. coli-Induced Effects on Epithelial Host Cell Height, Cell-Substrate Interactions, and Endocytic Processes by Infrared Surface Plasmon Spectroscopy

Enteropathogenic Escherichia coli (EPEC) is an important, generally non-invasive, bacterial pathogen that causes diarrhea in humans. The microbe infects mainly the enterocytes of the small intestine. Here we have applied our newly developed infrared surface plasmon resonance (IR-SPR) spectroscopy approach to study how EPEC infection affects epithelial host cells. The IR-SPR experiments showed that EPEC infection results in a robust reduction in the refractive index of the infected cells. Assisted by confocal and total internal reflection microscopy, we discovered that the microbe dilates the intercellular gaps and induces the appearance of fluid-phase-filled pinocytic vesicles in the lower basolateral regions of the host epithelial cells. Partial cell detachment from the underlying substratum was also observed. Finally, the waveguide mode observed by our IR-SPR analyses showed that EPEC infection decreases the host cell's height to some extent. Together, these observations reveal novel impacts of the pathogen on the host cell architecture and endocytic functions. We suggest that these changes may induce the infiltration of a watery environment into the host cell, and potentially lead to failure of the epithelium barrier functions. Our findings also indicate the great potential of the label-free IR-SPR approach to study the dynamics of host-pathogen interactions with high spatiotemporal sensitivity.

Activation of virus uptake through induction of macropinocytosis with a novel polymerizing peptide

A 27-aa peptide (P27) was previously shown to decrease the accumulation of human immunodeficiency virus type 1 (HIV-1) in the supernatant of chronically infected cells; however, the mechanism was not understood. Here, we show that P27 prevents virus accumulation by inducing macropinocytosis (MPC). Treatment of HIV-1- and human T-cell lymphotropic virus type 1 (HTLV-1)-infected cells with 2-10 μM P27 caused cell membrane ruffling and uptake of virus and polymerized forms of the peptide into large vacuoles. As demonstrated by electron microscopy, activation of MPC did not require virus or cells infected with virus, as P27 initiated its own uptake in the absence of virus. Inhibitors of MPC, Cytochalasin D and amiloride, decreased P27-mediated uptake of soluble dextran and inhibited P27-induced virus uptake by >60%, which provides further evidence that P27 induces MPC. In CD4(+) HeLa cells, HIV-1 infection was enhanced by P27 up to 4-fold, and P27 increased infection at concentrations as low as 20 nM. The 5-aa C-terminal domain of P27 was necessary for virus uptake and may be responsible for the polymerization of P27 into fibrils. These forms of P27 may play a key role in triggering MPC, making this peptide a useful tool for studying virus uptake and infection, as well as MPC of other macromolecules.

Ultrastructural pathology of vascular endothelial in patients with premalignant and malignant cervix lesions infected with papillomavirus

The purpose of this study was to determine the ultrastructural of vascular endothelial and relationship of the human papilloma virus (HPV) infection in patient with cervix lesions. Fifty-eight (58) tissue samples from the uterine cervix were obtained from patients with cervical intraepithelial neoplasia (CIN) and human papillomavirus infection at a public outpatient clinic in Aragua State, Venezuela. For the ultrastructural study, routine transmission electron microscopy techniques were used as well as polymerase chain reaction (PCR) for HPV. In the ultrastructural study (figure 3) NIC I sample with HPV type 6 infection. This section shows a capillary with reduplicated basement membrane and the endothelial cell cytoplasm widened (figure 4) Uterine cervix NIC II sample infected with HPV type 16. A mastocyte is shown. Note abundant collagen fibrils.( figure 5) NIC III sample with infection by HPV type 16. Capillary basement membrane is duplicated . Endothelial and pericyte cytoplasms are widened. Note in the pericyte the presence of pinocytotic vesicle.(figure 6) Invasive cervix cancer with HPV type 16. The widened endothelial cell cytoplasm shows prolongations into the lumen. Note the presence of primary lysosomes and pinocytotic vesivles.HPV11 was identified and both endothelial cytoplasm prolongations into the lumen and thickening of the endothelial wall were clearly seen. Changes of microvascular tissue in premalignant lesions and increased thickness of the endothelial capillary walls in malignant lesions of the uterine cervix indicated the activation of angiogenesis.

THE FINE STRUCTURE OF THE EYE IN GLOMERIS (DIPLOPODA)

SUMMARY The ocellus of Glomeris consists of a corneal lens, corneagenous and retinal cells. Basally the optical calyx is, bounded by a connective sheath. The cytoplasm of the corneagenous cells contains a few organelles; numerous pigment granules are present in the perinuclear zone. The external surface of the corneagenous cells is covered with short microvilli. The retinal cells have microvilli which are directed toward the apical surface of the photoreceptoral process. The photoreceptoral cytoplasm under the inner microvillar border is highly vacuolated: it also contains large intercellular lacunae, tubules and cisternae of the smooth endoplasmic reticulum and pinocytotic vesicles. Mitochondria, pigment granules, multivesicular bodies and Golgi's apparatus are localized between the microvillar border and the photoreceptoral nuclear region. In this latter region the cytoplasm contains mitochondria, rough endoplasmic reticulum and a few pigment granules. The retinal cell axons, containing numerous neurotu...

ULTRASTRUCTURE OF THE CELLS OF THE BOUNDARY LAYER OF SMALL VESSELS IN THE DIGESTIVE GLAND OF THE GASTROPOD PULMONATE EOBANIA VERMICULATA (MÜLLER)

SUMMARY We have described the vascular network of the digestive gland of Eobania vermiculata (Muller), with special reference to the ultrastructure of endothelial-like cells forming the capillary wall. These cells functionally correspond to elements of the normal endothelium but possess some exclusive ultrastructural features. The particular position of the cell nuclei and the relationship to the surrounding connective tissue (the loose perivascular connective tissue and interstitial vesicular cells) are shown. Irregular microvilli and pinocytosis vesicles are found on both inner and outer surfaces and oriented bundles of filaments occupy the central portion of the cytoplasm, anchoring to the plasmalemma. The hypothesis is advanced that these filaments are contractile in nature and, therefore, endothelial-like cells are retained capable of autoregulative processes, in order to adjust the calibre of the capillary lumen according to the rate of blood-tissue exchanges.

Tadanafil increases microvascular permeability in mouse brain lymphoma models

Objective To study about Tadalafil increasing microvascular permeability in mouse brain lymphoma models.Methods Comparatively analyze the influence of tadalafil on cerebral microvascular permeability in the mouse brain lymphoma models,by the approaches of using Evan's Blue to test the microvascular permeability,testing concentrations of methotrexate (MTX) by HPLC,and studying ultrastructures by transmission electron microscope.Results The microvascular permeability in tumor-bearing mice treated with Tadalafil were significantly higher than that in the other groups (P ＜ 0.05).The concentration of MTX increased nearly 1.8 times in tumor tissue with Tadalafil pre-treatment.The increment were significantly higher than that in the other groups (P ＜ 0.05).Numerous pinocytotic vesicles in the cytoplasm of the endothelial cells were observed obviously in Tadalafil pre-treated mouse tumor.Conclusion Phosphodiesterase type 5 inhibitor,Tadalafil,could increased the capillary permeability of the tumor tissue in mouse brain lymphoma models. Key words: Microvascular permeability; Tadalafil; Evan's Blue; MTX; Lymphoma

Aquaporin 4 expression and ultrastructure of the blood-brain barrier following cerebral contusion injury.

This study aimed to investigate aquaporin 4 expression and the ultrastructure of the blood-brain barrier at 2–72 hours following cerebral contusion injury, and correlate these changes to the formation of brain edema. Results revealed that at 2 hours after cerebral contusion and laceration injury, aquaporin 4 expression significantly increased, brain water content and blood-brain barrier permeability increased, and the number of pinocytotic vesicles in cerebral microvascular endothelial cells increased. In addition, the mitochondrial accumulation was observed. As contusion and laceration injury became aggravated, aquaporin 4 expression continued to increase, brain water content and blood-brain barrier permeability gradually increased, brain capillary endothelial cells and astrocytes swelled, and capillary basement membrane injury gradually increased. The above changes were most apparent at 12 hours after injury, after which they gradually attenuated. Aquaporin 4 expression positively correlated with brain water content and the blood-brain barrier index. Our experimental findings indicate that increasing aquaporin 4 expression and blood-brain barrier permeability after cerebral contusion and laceration injury in humans is involved in the formation of brain edema.

The ultrastructure of the muscle coat of human gastro-oesophageal junction, with special reference to "interstitial cells of Cajal".

The muscle coat of the human lower oesophageal sphincter and stomach was studied 5 cm above and 4 cm below the gastro-oesophageal junction. Four subjects were operated on for motility disorders of the esophagus, two for a hypertensive lower oesophageal sphincter and two for an epiphrenic diverticulum; six subjects were operated on for oesophageal or gastric carcinomas. Specimens were fixed in phosphate-buffered OsO4, embedded in Epon, contrasted with uranyl acetate and lead citrate and observed under a Siemens Elmiskop Ia electron microscope. Both the oesophageal and gastric muscle cells, which showed features typical of this cell type, were innervated by multiple varicosities that were rich in synaptic vesicles; these varicosities were generally rarely encountered at distances less than 1000 Å from muscle cells. Only a very few, close neuromuscular junctions were detected. Special cells, which correspond to the “interstitial cells of Cajal” as reported by other authors, were discerned at the periphery of muscle cell bundles. These cells were characterized by an elongated cell body with many thin branches and an oval, sometimes indented nucleus. Some pinocytotic vesicles were located at the cell periphery. These cells were surrounded by a discontinuous basal lamina and were seen in close contact with each other and with muscle cells; the close contact areas were often very wide. The cytoplasm contained variable amounts of mitochondria, a well-developed smooth endoplasmic reticulum and a Golgi complex. As a characteristic feature, bundles of thin filaments were located at the cell periphery and were attached to electron-dense areas of the cell membrane. Morphologically, these filaments resembled myofilaments; they were present in variable amounts and were sometimes very numerous. The observation that the cytoplasmic organelles and filaments varied in number, is probably related to the different functional properties of these cells. Interstitial cells were richly innervated by varicose nerve fibers that were densely packed with synaptic vesicles; many close junctions to nerve endings were also detected. These morphological data lead us to assume that the interstitial cells demonstrated by the electron microscope do not correspond to the cells initially identified by Cajal and cannot even be considered connective tissue cells. We propose that they are specialized smooth muscle cells that are involved in generating spontaneous, myogenic electrical activity in the gastrointestinal tract.

The rationale for the application of laserophoresis of biologically active compounds

Laserophoresis is a technique for the transcutaneous administration of biologically active compounds by means of low-intensity laser radiation (LFLR). It is currently regarded as a most promising method for the integrated application of a pharmaceutical substance and a physical factor. At present laserophoresis of various medicinal preparations is successfully used after preliminary experimental studies of their phoretic properties for the treatment of various inflammatory and dystrophic conditions as well as for the prevention of skin ageing. The most important route for the administration of the majority of drug preparations is through the shunts provided by perspiratory glands and hair follicles. Another essential factor determining the potential possibility of drug penetration through the skin is the characteristic of the substance chosen for the administration, such as its molecular weight, chemical structure, conformation, and hydrophilic properties. However, the most likely mechanism underlying the transport of the substance through the glandular cells of perspiratory glands and epithelial cells of hair follicles is pinocytosis, i.e. the process integrating exocytosis and endocytosis. To-day, the majority of the researchers lay emphasis on thermodynamic triggering of Ca2+-dependent processes as the primary mechanism behind the biological action of low-intensity laser radiation. Both exocytosis and endocytosis being the Ca2+-dependent processes, the liberation of Ca2+-ions under the influence of LFLR causes the activation of pinocytosis as a whole.

Morphological features of pathological membrane of inferior vena cava associated with Budd-Chiari syndrome

Objective To investigate the morphological features of a diseased inferior vena cava (IVC) diaphragm associated with Budd-Chiari syndrome,and to explore the pathogenic mechanisms.Methods Ten patients with a diseased IVC diaphragm associated with Budd-Chiari syndrome underwent radical resection in our hospital frome October 2007 to December 2010.We assessed the gross morphological features of these diaphragms.The structure of the diseased diaphragms was compared with that of the IVC retrohepatic segment using light and electron microscopy.Results The diseased diaphragms were located within 2.0 cm from the junction of the IVC and the right atrium.The diaphragms had thick edges and relatively thin centers; their surface connected with the inner membrane of the IVC.A mural thrombus was observed in the IVC below the diaphragm in nine patients,with partial calcification of the diaphragm in five patients.Light microscopy revealed that the diaphragm was composed of massive homogencous collagen fibers and fibroblasts.The collagen was highly disorganized and some collagen fibers showed hyaline degeneration.The edges of the diaphragms showed proliferation of fibrous connective tissue,together with some pathological changes,including the presence of some granulation tissue and neovessels.The structures of the normal inner,middle and outer membranes of the IVC remained intact.Electron microscopy revealed the diaphragms contained a relatively high number of fibroeytes,and a small number of endotheliocytes on their surface.Most of the cristae inside the endotheliocytes were disconnected from the inner membranes and fused,and were therefore blurred or missing,The rough endoplasmic reticulum was also slightly dilated.Apoptotic cells were infrequent,and were generally smaller than expected.The endotheliocytes on the normal IVC walls were well organized,showing a striped distribution.Mitochondria,rough endoplasmic reticolum and pinocytotic vesicles were found inside the endotheliocytes.Collageo fibers and elastic fibers below the endotheliocytes were sparse.Conclusion The diseased IVC diaphragm associated with Budd Chiari syndrome mainly develops as a result of fibrocyte proliferation,although IVC injury and inflammatory reactions may also be involved. Key words: Budd-Chiari syndrome; Inferior vena cava; Pathological membrane

Cell‐Penetrating Peptides as Delivery Vehicles for a Protein‐Targeted Terbium Complex

Release after transmission: Arginine-rich, cell-penetrating peptides (CPPs) mediate cytoplasmic delivery of trimethoprim (TMP)-terbium complex conjugates and selective, intracellular labeling of E. coli dihydrofolate reductase (eDHFR) fusion proteins. A disulfide bond linking CPP and cargo is reduced following uptake. CPP conjugation can be used to deliver otherwise cell-impermeable, ligand-fluorophore conjugates.

Zymographic and ultrastructural evaluations after low-level laser irradiation on masseter muscle of HRS/J strain mice

Low-level laser therapy (LLLT) has been widely used in the treatment of the stomatognathic system dysfunction; however, its biological effect remains poorly understood. This study evaluated the effect of LLLT (GaAlAs, 780 nm, 20 J/cm(2), 40 mW) on masseter muscle of HRS/J mice after different numbers of laser irradiations (three, six, and ten) for 20 s in alternate days. Three experimental groups were defined according to the number of laser irradiations and three control groups (n=5) were used. On the third day after the last irradiation, all animals were killed and the masseter muscle was removed and processed for the following analysis: (a) transmission electron microscopy, (b) zymography, (c) immunohistochemistry for vascular endothelial growth factor (VEGF) and VEGFR-2. The results showed: (a) with six laser applications, a dilation of T tubules, and sarcoplasmic reticulum cistern, increased pinocytosed vesicles in the endothelium; with ten laser applications, few pinocytic vesicles in the endothelium and condensed mitochondria. (b) Under the conditions of this study, the synthesis of other matrix metalloproteinases was not observed, only the MMP-2 and -9. (c) After ten laser irradiations, immunostaining was observed only for VEGFR-2. We conclude that after six laser applications, ultrastructural changes may facilitate the Ca(+2) transfer to cytosol and increase the fluid transport from one surface to another. The ultrastructural changes and no immunostaining for VEGF with ten applications may decrease the metabolic activity as well as damage the angiogenic process, suggesting that an effective number of laser applications may be less than ten, associating to this therapy a better cost-benefit.

Low-Frequency Ultrasound Irradiation Increases Blood–Tumor Barrier Permeability by Transcellular Pathway in a Rat Glioma Model

Low-frequency ultrasound (LFU) irradiation under certain acoustic intensity can increase blood-brain barrier permeability non-invasively and reversibly. The aim of this study was to find out the effect of LFU irradiation on blood-tumor barrier (BTB) permeability in rat C6 glioma model and the possible mechanism. In this research, Evans blue and H&E staining were used to evaluate the optimal parameter of LFU to open the BTB without damaging the normal brain tissue. Transmission electron microscopy was used to observe the changes of the number of pinocytotic vesicles in cerebral or glioma microvascular endothelial cells. The phosphorylation of tyrosine kinase Src, caveolin-1, and caveolin-2 was detected by western blot. The distribution and expressing levels of caveolae proteins, caveolin-1 and caveolin-2, were detected by immunohistochemical and immunofluorescent staining, RT-PCR, and western blot. Our research data showed that, in rat C6 glioma model, LFU irradiation at a frequency of 1 MHz, a power of 12 mW, and exposure time of 20 s induced the increase of BTB permeability temporally, which reached a peak at 1.5 h, then decreased and restored to normal level at 12 h after LFU irradiation. In the glioma microvascular endothelial cells of rat glioma model, LFU irradiation induced a significant increase of the pinocytotic vesicles' density. The phosphorylation of Src, caveolin-1, and caveolin-2 began to increase at 0.5 h and reached a maximum at 1 h. Immunohistochemical and immunofluorescent staining showed that caveolin-1 and caveolin-2 were co-localized in the glioma microvascular endothelial cells and glioma cells. The mRNA and protein expression levels of caveolin-1 and caveolin-2 were up-regulated, reached the peak value at 1.5 h, and re-normalized at 12 h after LFU irradiation. These results demonstrated that LFU irradiation increased BTB permeability by promoting transcellular transport in glioma microvascular endothelial cells. The phosphorylation of tyrosine kinase Src, caveolin-1, caveolin-2 and up-regulation of caveolin-1 and caveolin-2 were involved in LFU-induced caveolae-mediated endocytosis.

Plexiform hybrid granular cell tumor/perineurioma: A novel variant of benign peripheral nerve sheath tumor with divergent differentiation

The descriptive term hybrid peripheral nerve sheath tumor refers to any neoplasm of the neurilemmal apparatus composed of more than one pathologically defined tumoral equivalent derived from its constituent cells. Within this uncommon nosological category, participation of granular cell tumor – a neoplasm of modified Schwann cells – has been reported only exceptionally. We describe a hitherto not documented variant composed of an organoid mixture of granular cell tumor and perineurioma with plexiform growth. A solitary subcutaneous nodule of 1.5cm diameter was excised from the right ring finger of a 19-year-old female with no antecedents of neurofibromatosis or relevant trauma. Histology revealed a monotonous, yet cytologically dimorphic proliferation of classical granular cells intermingled with flattened, inconspicuous perineurial cells. Immunohistochemical double labeling detected expression of S100 protein in the former and of EMA and GLUT-1 in the latter. While the respective staining patterns for S100 protein and EMA or GLUT-1 tended to be mutually exclusive, a minority of cells exhibited transitional granular cell/perineurial immunophenotype. Electron microscopy permitted direct visualization of a plethora of lysosomes in the granular cell moiety, and of pinocytotic vesicles and tight junctions in perineurial cells. Intratumoral axons were not detected. Expanding intraneurally, the lesion showed discrete encapsulation by the local perineurium, and resulted in plexiform growth. The MIB-1 labeling index averaged 1%. We interpret our findings as supporting evidence for the dual cell lineage to have arisen through metaplasia, with the tumor's dynamics probably having been driven by the granular cell component.

Claudin-1 and Glucose Transporter 1 Immunolabelling in a Canine Intraneural Perineurioma

A 4-year-old male leonberger was diagnosed tentatively with a peripheral nerve sheath tumour of the median nerve based on neurological examination, electrodiagnostic testing and ultrasound evaluation. The lesion was excised and submitted for pathological examination. Histopathology revealed an irregularly enlarged, hypercellular nerve fascicle with neoplastic tissue consisting of a uniform population of spindle-shaped cells arranged in 'pseudo-onion bulb-like' whorls around axons. Minimal anisocytosis and anisokaryosis were present, together with a low mitotic index. Electron microscopy showed spindle cells with a discontinuous basal membrane and intercellular junctions, as well as pinocytotic vesicles. Immunohistochemistry for neurofilament, S100 and glucose transporter 1 was negative, whereas labelling for claudin-1 and laminin was positive. Based on these observations, a definitive diagnosis of intraneural perineurioma was made.

A Soft Tissue Perineurioma and a Hybrid Tumor of Perineurioma and Schwannoma

Perineuriomas are composed of differentiated perineurial cells. Perineuriomas have been recently recognized by the immunoreactivity for epithelial membrane antigen (EMA). Microscopically, perineuriomas show proliferation of spindle cells with wavy nuclei and delicate elongated bipolar cytoplasmic processes. The tumor cells are usually negative for the S-100 protein. Ultrastructurally, perineurial cells reveal slender, nontapered processes containing pinocytic vesicles and discontinuous basal lamina. Interestingly, hybrid tumors of benign peripheral nerve sheath tumor (PNST) have been recently reported by using immunohistochemical and ultrastructural investigations. Herein, we report a case of soft tissue perineurioma arising in the skin of a 56-year-old female; another case of a hybrid tumor of perineurioma and schwannoma in the posterior mediastinum occurred in a 53-year-old male, which is the first case of the hybrid PNST tumor reported in Korea.

Ultrastructural and Immunohistochemical Studies on Uptake and Distribution of FITC-Conjugated PLGA Nanoparticles Administered Intratracheally in Rats

Polylactide-glycolide (PLGA) nanoparticles have been developed as pulmonary drug delivery carriers. To investigate their behavior, small- (d50 = 74 nm) and large-sized (d50 = 250 nm) FITC-conjugated PLGA nanoparticles were intratracheally administered to rats and were traced for 5, 30 and 60 minutes and 24 hours after administration (HAT). Immunohistochemically, a, FITC-positive reaction was observed in type-I alveolar epithelial cells (type-I AEC), endothelial cells and alveolar macrophages in the lungs from 5 minutes after treatment (MAT) to 24 HAT in both nanoparticle groups. In the kidneys, a positive reaction was observed in proximal tubular epithelial cells at 30 MAT; the reaction peaked at 60 MAT and was reduced at 24 HAT, while no positive reaction was seen in other sites. Ultrascructurally, the number of membrane-bound vesicles, which were approximately 70 nm in size and hard to distinguish from pinocytic vesicles, apparently increased in type-I AEC and endothelial cells at 5 MAT in the small-sized group, in comparison with the control group receiving physiological saline. The number of vesicles in the large-sized group was almost same as that in the control group. On the other hand, in both nanoparticle groups, lysosomes filled with nanoparticles appeared in alveolar macrophages from 30 MAT to 24 HAT. These results indicate that PLGA nanoparticles might be quickly transferred from the alveolar space to the blood vessel via type-I alveolar epithelial cells and excreted into urine, and that there is a threshold for particle size, less than approximately 70 nm in diameter, with regard to absorption through the alveolar wall.

Ultrastructural immunolocalization of basic fibroblast growth factor in endothelial cells: morphologic evidence for unconventional secretion of a novel protein

Basic fibroblast growth factor (bFGF) is one of the most potent angiogenic factors. Unlike many other growth factors, bFGF lacks a classic peptide sequence for its secretion. Recent studies suggest that there is an unconventional secretory pathway for this growth factor. The aim of this study was to identify the specific location of bFGF in endothelial cells and to find morphologic evidences concerning its synthesis, storage and release from endothelial cells. The capillaries in hippocampus, adrenal gland, kidney, peripheral nerves as well as the vessels in connective tissues were analysed by using immunogold labeling techniques at electron microscope level. Results show that endogenous bFGF is mainly located in the nuclei of endothelial cells. Slight immunoreactivity is found in the cytoplasm. Immunolabeling is notably absent in pinocytotic vesicles, Golgi complexes, endoplasmic reticulum, nuclear membrane and intercellular junctions. These results provide morphologic evidence suggesting that endothelial cells might export bFGF via unique cellular pathways that are clearly distinct from classical signal peptide mediated secretion and/or release of this protein could be directly through mechanically induced disruptions of these cells. The current study support the recent hypothesis related with unconventional secretory pathway for bFGF as some other "cargo" proteins.

Meningial perineurioma: A benign peripheral nerve sheath tumor in a previously unrecognized central nervous system location, mimicking meningioma

Perineurioma is an uncommon, mostly benign, spindle-cell tumor of peripheral nerve sheath origin with a predilection for the soft tissues. Although increasing awareness points to the sites of involvement by perineurioma possibly being as ubiquitous as those frequented by schwannian tumors, only one intracerebral example has been described to date. We report on a surgically resected perineurioma of the falx cerebri in an 86-year-old woman. Preoperative imaging showed an enhancing extraaxial mass of 6 cm × 5.7 cm × 3.7 cm. Histologically, the tumor consisted of a proliferation of spindle cells interwoven by a lattice of basal lamina. Alongside a prevailing soft tissue perineurioma pattern, sclerosing and reticular areas were seen as well. Tumor cells coexpressed EMA and GLUT-1, and a minority immunoreacted for smooth muscle actin. Pericellular basal lamina was decorated with collagen type IV. No staining for S100 protein was detected. Mitotic activity was virtually absent, and the MIB1 labeling index averaged 2%. Ultrastructural examination revealed abundant pinocytotic vesicles within and conspicuous tight junctions between slender cytoplasmic processes which, in turn, were encased by discontinuous basal lamina. FISH analysis confirmed loss of at least part of one chromosome 22q. This observation calls attention to perineurioma as a novel item in the repertoire of low-grade meningial spindle cell neoplasms, in the differential diagnostic context of which it is apt to being misconstrued as either meningioma, solitary fibrous tumor, or neurofibroma. Confusion with the latter bears the risk of overgrading innocuous features of perineurioma as criteria for malignancy.