Production of intestinal and other tumors by 1, 2-dimethylhydrazine dihydrochloride in mice. I. A light and transmission electron microscopic study of colonic neoplasms

Single or ten weekly subcutaneous injection(s) of 1, 2-dimethylhydrazine dihydrochloride were administered separately to Swiss mice. The repeated application gave rise mainly to high incidences of tumors in the large intestine. These neoplasms occurred most frequently in the colorectal area and in cecum adjacent to ileum. Light microscopically, these lesions were classified as polypoid adenomas and adenocarcinomas. Most of the adenocarcinomas were highly invasive, although they metastasized rarely. The fine structure of the malignant cells exhibited features typical of columnar absorptive cells. A distinctive alteration was the disorderly arrangement and abnormal size and shape of the microvilli. In addition, the cells exhibited numerous free ribosomes, little RER, priminent Golgi bodies, and uniformly dispersed nuclear chromatin. Morphologically, the intestinal tumors were similar to those found in man. In addition, the repeated administration of 1, 2-DMH also induced significant incidences of neoplasms in blood vessels, lungs, anus, and kidneys while the single application produced tumors in blood vessels and liver. The main hypotheses attempting to explain the selective induction of large intestinal neoplasms are discussed.     

Nipple aspirate fluid: a promising non-invasive method to identify cellular markers of breast cancer risk

To evaluate the feasibility of nipple aspiration and to identify intermediate markers of breast cancer risk, nipple aspirate fluid (NAF) was collected from 177 subjects using a modified breast pump. The first 33 subjects demonstrated that we could obtain NAF quickly, reliably and repeatedly. Specimens from the remaining 144 subjects were collected to evaluate promising cellular biomarkers. NAF was obtained in 167 out of 177 (94%) subjects overall and in 99% of the 144 most recent subjects. Sufficient NAF was obtained to evaluate cytology in 160 out of 167 (96%) cases and specimens were sufficiently cellular to analyse DNA markers in 53% of cases. Among the last 144 subjects, menopausal status did not influence the ability to obtain NAF. NAF cytology correlated with increased breast cancer risk (P = 0.002). Using computerized image analysis of NAF epithelial cells, DNA index (P = 0.0002), percentage of cells in G2M (P = 0.05) and percentage of cells with hypertetraploidy (P = 0.002) increased as cytology became more abnormal. Our data indicate that NAF can be obtained in essentially all eligible subjects; that breast epithelial cells are evaluable in > 95% of NAF samples for cytology and in over half of NAF samples for DNA index (ploidy) and cell cycle analysis; and that abnormal NAF cytology correlates with increased breast cancer risk. This suggests that biomarkers identified in nipple aspirate fluid may prove useful either as an adjunct to currently accepted breast cancer screening methods, or to evaluate response to a chemopreventive agent.     

Enzymatic activity of pig heart mitochondrial malate dehydrogenase monomolecular films by surface exchange technique

A technique for studying the catalytic activity of enzymes spread as a film at an air-water interface, by exchanging the subphase under the film to remove unspread enzyme molecules, was developed, and its effectiveness was studied using surface-spread mitochondrial malate dehydrogenase. Mitochondrial malate dehydrogenase formed stable films which gave reproducible pi-A curves. The enzyme activity was measured by the oxidation rate of reduced nicotinamide adenine dinucleotide (NADH) in the presence of the substrate oxalacetic acid. Oxalacetic acid and NADH were injected into the subphase. The catalytic activity of the enzyme was dependent on the surface pressure of the film. The maximum catalytic activity was observed at a surface pressure of 4.4 dynes/cm. The activity was higher at intermediate surface pressures than at very low or very high surface pressures. A high bulk catalytic activity was observed in the unstable region, i.e., at a high degree of compression, of the film. The catalytic activity of the surface-spread enzyme was only a fraction of an equivalent amount of enzyme in solution.     

Pancreatic neoplasms induced in Syrian golden hamsters. I. Scanning electron microscopic observations

Pancreases from Syrian golden hamsters treated with N-nitrosobis(2-hydroxy-proply)amine for 10 to 25 weeks were examined under scanning electron microscopy (SEM). Findings indicate that the neoplasms originated from the ductal epithelium and developed progressively. Adenomas were lined by epithelium of differing cells types, ranging from a flat singly ciliated form to cuboidal-columnar types, or to mixed cell populations. The epithelial lining of the ductal carcinomas exhibited tubular and papillary cystic spaces, and cell surfaces were similar to the cuboidal and columnar epithelium of adenomas and of ductal epithelial hyperplasia. However, microvilli were dense and of varied lengths. The SEM observations correlated with patterns seen in routine histologic preparations.     

Use of proteins to minimize the physical aging of EUDRAGIT sustained release films

The objective of this study was to investigate the influence of two proteins, albumin and type B gelatin, on the physical aging of EUDRAGIT® RS 30 D and RL 30 D coated theophylline pellets. The physicomechanical properties of sprayed films, thermal properties of cast films, influence of proteins on the zeta potential and particle size of the dispersion, and the release of proteins from cast films under simulated dissolution conditions were investigated. The release rate of theophylline decreased significantly over time from pellets coated with an acrylic dispersion containing 10% albumin when there was no acidification of the acrylic dispersion; however, when pellets were coated with an acidified EUDRAGIT®/albumin dispersion, the theophylline release rate was stable for dosage forms stored in the absence of humidity. The drug release rate was faster for pellets coated with acrylic dispersions containing 10% gelatin compared to the albumin-containing formulations. When sprayed films were stored at 40°C/75% RH, the water vapor permeability decreased significantly for both EUDRAGIT® films and those containing EUDRAGIT® and albumin; however, there was no significant change in this parameter when 10% gelatin was present. Albumin was released from the acrylic films when the pH of the dissolution media was below the isoelectric point of the protein while no quantitative release of gelatin was observed in pH 1.2 or 7.4 media. The effect of gelatin to prevent the decrease in drug release rate was due to stabilization in water vapor permeability of the film. Acidification of the polymeric dispersion resulted in electrostatic repulsive forces between albumin and the acrylic polymer, which stabilized the drug release rate when the dosage forms were stored in aluminum induction sealed containers at both 40°C/75% RH and 25°C/60% RH.     

The Effect of Thyme Oil Low-Density Polyethylene Impregnated Pellets in Polylactic Acid Sachets on Storage Quality of Ready-to-Eat Avocado

After earlier promising results for the control of anthracnose in avocado fruit by thyme vapours, our studies were extended to commercial use in tray packs. The effect of thyme oil low-density polyethylene impregnated pellets (TO-LDPE-P) in polylactic acid (PLA) sachets was investigated for the control of anthracnose and retention of dietary phytochemicals, fatty acid composition, D-mannoheptulose sugar and fruit quality in ready-to-eat avocado fruit. The 10% TO-LDPE-P significantly reduced the incidence severity of anthracnose and enabled the retention of dietary phytochemicals (p-coumaric, ferulic and caffeic acid, catechin and epicatechin), fatty acids, mannoheptulose, fruit firmness and taste compared to the currently used prochloraz^® fungicide treatment. The results of this study strongly suggest the incorporation of 10% TO-LDPE-P in PLA sachets in commercial avocado tray packs as a natural option to improve fruit health, dietary phytochemicals, fatty acid composition and consumer satisfaction.     

Controlled Release of a Poorly Water-Soluble Drug from Hot-Melt Extrudates Containing Acrylic Polymers

ABSTRACT

Controlled release tablets containing a poorly water-soluble drug, indomethacin (IDM), acrylic polymers (Eudragit® RD 100, Eudragit® L 100, or Eudragit® S 100), and triethyl citrate (TEC) were prepared by hot-melt extrusion. The physicochemical and IDM release properties of the controlled release hot-melt extrudates were investigated. Indomethacin (IDM) was found to be both thermally and chemically stable following hot-melt extrusion processing and displayed a plasticizing effect on Eudragit® RL PO as demonstrated by a decrease in the glass transition temperatures of the polymer. The inclusion of either Pluronic® F68, Eudragit® L 100, or Eudragit® S 100 in the powder blend containing Eudragit® RD 100 prior to processing increased the rate of release of the IDM from the extrudates. An increase in the media pH and a decrease in the granule particle size also increased the rate of release of IDM. The inclusion of TEC up to 8% in the granule formulation or compressing the granules into tablets had no significant effect on the drug release rate. Indomethacin (IDM) was transformed from a crystalline Form I into an amorphous form in the Eudragit® RD 100 granules following hot-melt extrusion. The thermal processing facilitated the formation of a solid solution with a continuous matrix structure that was shown to control drug diffusion from the extrudates.     

High Energy Ordered Mixture for Improving the Dissolution Rate of Sparingly Soluble Compounds

Bioavailability of a sparingly soluble drug is often limited by the rate of dissolution of the drug substance. The drug in a micronized form is generally employed to maximize the bioavailability. However, the micronized drugs tend to agglomerates and do not always exhibit an improved dissolution rate. In this study, a simple processing using a high energy mill was demonstrated as an effective means to utilize the entire surface area available for drug release of the micronized drug. An experimental hydrophobic drug in a micronized form was milled with a carrier, hydrous lactose using Micropulverizer to achieve a uniform mixture so-called “high energy ordered mixture”. The high energy ordered mixture provided a contact surface area taking part in dissolution 4-fold greater than the micronized drug agglomerates. Therefore, the dissolution was significantly improved, irrespective of test parameters such as agitation and the presence of surfactant. This high energy ordered mixture provided the advantages over a simple ordered mixture for: (i) complete deaggregation of the micronized drug to fine primary particles, (ii) improving the efficiency of the carrier by increasing contact surface area, and (iii) enhancing the bonding effect between the drug and lactose particles due to free water molecules released from the crystal lattices of hydrous lactose during milling. This procedure could be applied to overcome dissolution problems of sparingly soluble drugs with cohesive nature.     

Dorsal horn projection targets of ON and OFF cells in the rostral ventromedial medulla

1. The rostral ventromedial medulla (RVM) participates in the modulation of nociceptive transmission by spinal cord neurons. Previous anatomic studies have demonstrated that RVM neurons project to laminae I, II, and V of the dorsal horn; laminae VII and VIII of the intermediate and ventral horns; the intermediolateral column; and lamina X. The RVM contains at least three physiologically defined classes of neurons, two of which, the ON and the OFF cells, have been implicated in nociceptive modulation. Because these cells classes are intermingled in the RVM, it has not been possible to determine the spinal laminar projection targets of ON and OFF cells by anatomic methods. Therefore in the current study we employed antidromic microstimulation methods to determine the laminar projections of two of the three classes of RVM neurons, the ON and the OFF cells. 2. In lightly anesthetized (with methohexital sodium) rats, single-unit extracellular recordings were made from 48 RVM neurons that were physiologically characterized as ON (30) or OFF (18) cells. The recording locations of 45 of these neurons were recovered. Thirty-seven were found in the nucleus raphe magnus and eight were located near its dorsal and lateral borders. 3. Thirty-two physiologically identified RVM neurons (18 ON and 14 OFF cells) were antidromically activated from the cervical spinal cord using a monopolar stimulating electrode. The stimulating electrode was moved systematically in the white matter until antidromic activation could be produced with currents of < or = 20 microA (6.1 +/- 0.7 microA, mean +/- SE). The points from which minimum currents were required to antidromically activate the neurons were located mainly in the ipsilateral dorsolateral funiculus (DLF) (27 of 32). In a few cases, lowest antidromic threshold currents were found near the border between the DLF and ventrolateral funiculus (VLF) or, rarely, in the VLF itself. In these cases, the cell recordings were found to be near the dorsal boundary of the RVM. 4. While one electrode was used to stimulate the parent axon in the lateral funiculus, a second was used to explore the gray matter for the presence of collateral branches. The identification of a branch was initially determined by an increase in antidromic latency. At the same rostrocaudal plane of the spinal cord, stimulation of the DLF induced an antidromic spike that invaded the neuron earlier than the antidromic spike elicited by stimulation in the gray matter. Collateral branches were confirmed by establishing that the location of the minimum threshold point for antidromic activation of the neurons from the second electrode was in the gray matter, that the minimum current required to antidromically activate the neuron from that point was too low to activate the parent axon in the DLF, and that a collision occurred between the spikes induced by the two stimulating electrodes. 5. In 17 cases, physiologically identified RVM neurons (10 ON and 7 OFF cells) were antidromically activated from the gray matter of the cervical spinal cord using a current of 8.4 +/- 2.1 (SE) microA. Minimum threshold points for antidromic activation were found in laminae I-II (3 ON and 4 OFF cells), lamina V (5 ON and 6 OFF cells), and regions ventral to the lateral reticulated area (3 ON and 2 OFF cells) of the gray matter. As indicated by these numbers, some neurons were antidromically activated from more than one gray matter region. In general, all OFF cells and 9 of 10 ON cells were antidromically activated from low threshold points in either laminae I-II or lamina V. 6. In six cases, neurons were activated from separate points located in two or three different laminae of the gray matter. Three OFF cells were activated from laminae I-II and V, one OFF cell and one ON cell were activated from lamina V and from more ventral points, and one ON cell was activated from laminae I-II and from points ventral to lamina V.     

Interference‐aware clustering approach improving QoS for linear WSNs using a token‐based MAC protocol

Wireless sensor networks (WSNs) have received a lot of attention from both academia and industry due to the increasing need for ubiquitous computing for monitoring applications, the continuous advances in miniaturization of electronic devices, and the ultra‐low‐power wireless technologies. These innovations in technology have driven the curiosity to use sensor networks in a new kind of applications such as road track or railway monitoring, border monitoring, oil and gas, or even water pipeline monitoring. Due to the underlying linear topology of these applications, a new type of network, called a linear sensor network (LSN), has emerged. Because of the specific characteristics of this application and the resource constraints of sensors, some of the major challenges faced in LSNs are to reduce end‐to‐end delays, to maximize the packet delivery ratio to a sink, and an even distribution of the load between nodes. To achieve these objectives, it is necessary to control node‐to‐node packet traffic conditions and to manage radio interference created by simultaneously active nodes. This paper addresses these challenges and proposes a new method of clustering LSNs that reduces or controls radio interference risks in order to satisfy these objectives, application needs, and the resource limitations of sensor nodes in the best possible way. This method is applied for LSNs using a token‐passing mechanism to access the medium. The performance evaluation is conducted by using a realistic propagation model in the analytical evaluation and also a NS‐2 simulation process.