Lidocaine-loaded biodegradable nanospheres. I. Optimization Of the drug incorporation into the polymer matrix

Spherical nanoparticulate drug carriers made of poly(d,l-lactic acid) with controlled size were designed. A local anesthetic, lidocaine, a small hydrophobic molecule, was incorporated in the core with loadings varying from about 7 to 32% (w/w) and increasing with the particle size. Particles with sizes from about 250 to 820 nm and low polydispersity were prepared with good reproducibility; the polymer concentration (at constant surfactant concentration) governed the particle size. The large particles with a high loading ( approximately 30%) showed under in vitro conditions a slow release over 24-30 h, the medium sized carriers (loading of approximately 13%) released the drug over about 15 h, whereas the small particles with small loading ( approximately 7%) exhibited a rapid release over a couple of hours. It seems that the drug release rate is related to the state (crystallized or dispersed) of the drug incorporated in the polymer matrix.     

Effect of gamma-irradiation on flavour 5′-nucleotides,tyrosine, and phenylalanine in mushrooms (Agaricus bisporus)

The impact of gamma-irradiation on 5′-nucleotides and on the free amino acids tyrosine and phenylalanine in fresh mushrooms was studied. After irradiation the samples were freeze-dried to avoid enzyme induced chemical changes. Three 5′-nucleotides could be detected using HPLC–UV and LC–ESI-MS: adenosine 5′-monophosphate (AMP), guanosine 5′-monophosphate (GMP) and guanosine 5′-diphosphate (GDP). Irradiation significantly reduced (p = 0.05) the GDP concentration (22%). AMP showed a marked reduction (46%) only at 5 kGy. GMP, tyrosine, and phenylalanine were not affected by gamma-irradiation.     

Infiltration of fibrous preforms by a pure metal: Part V. Influence of preform compressibility

Infiltration by a pure matrix in the presence of preform deformation and partial matrix solidification is analyzed using a bounding approach for the preform rheology where solid metal is present. It is found, using parameters for the infiltration of short alumina fiber preforms by aluminum, that the two bounds are close in comparison to other factors of uncertainty in the prediction of infiltration rate. Using this approach, preform compression is shown to exert a significant influence on the infiltration rate for the system explored; in particular, the analysis shows the existence of an optimal value of applied pressure. Simplifications in the analysis are also presented, which yield fairly accurate results while easing their computation significantly.     

Inhibitory effect of theobromine on induction of angiogenesis and VEGF mRNA expression in v-raf transfectants of human urothelial cells HCV-29

STUDY DESIGN: Dissection and observation of the dorsal root ganglion of the second cervical spinal nerve bilaterally. OBJECTIVES: To determine the position of the C2 dorsal root ganglion and the heights of the C2 ganglion and its corresponding foramen. SUMMARY OF BACKGROUND DATA: The dorsal root ganglion has been well studied in the middle and lower cervical spine and in the lumbar spine. In no previous study are the position and height of the C2 dorsal root ganglion and its corresponding foramen described. METHODS: Fifteen cadaveric cervical spines were exposed posteriorly. The C2 nerve roots and ganglia were dissected between the arch of the atlas and the lamina of the axis. The heights of the C2 ganglion and foramen were measured. The location of the C2 ganglion was also macroscopically observed. RESULTS: The heights of the C2 ganglion and foramen are 5.7 +/- 0.8 mm and 7.7 +/- 1.2 mm, respectively. The C2 ganglion occupies 76% of the foramen height. All C2 dorsal root ganglia are confined within foramens between the arch of the atlas and the lamina of the axis. CONCLUSIONS: The C2 dorsal dorsal root ganglia are all proximally placed and occupy most of the foramen height, which may render the C2 ganglion vulnerable to entrapment.     

A simple breathing circuit minimizing changes in alveolar ventilation during hyperpnoea

Many clinical and research situations require maintenance of isocapnia, which occurs when alveolar ventilation (V'A) is matched to CO2 production. A simple, passive circuit that minimizes changes in V'A during hyperpnoea was devised. It is comprised of a manifold, with two gas inlets, attached to the intake port of a nonrebreathing circuit or ventilator. The first inlet receives a flow of fresh gas (CO2=0%) equal to the subject's minute ventilation (V'E). During hyperpnoea, the balance of V'E is drawn (inlet 2) from a reservoir containing gas, the carbon dioxide tension (PCO2) approximates that of mixed venous blood and therefore contributes minimally to V'A. Nine normal subjects breathed through the circuit for 4 min at 15-31 times resting levels. End-tidal PCO2 (Pet,CO2) at rest, 0, 1.5 and 3.0 min were (mean+/-SE) 5.1+/-0.1 kPa (38.1+/-1.1 mmHg), 4.9+/-0.1 kPa (36.4+/-1.1 mmHg), 5.0+/-0.2 kPa (37.8+/-1.6 mmHg) and 5.0+/-0.2 kPa (37.6+/-1.4 mmHg) (p=0.53, analysis of variance (ANOVA)), respectively; without the circuit, Pet,CO2 would be expected to have decreased by at least 2.7 kPa (20 mmHg). Six anaesthetized, intubated dogs were first ventilated at control levels and then hyperventilated by stepwise increases in either respiratory frequency (fR) from 10 to 24 min(-1) or tidal volume (VT) from 400 to 1,200 mL. Increases in fR did not significantly affect arterial CO2 tension (Pa,CO2) (p=0.28, ANOVA). Only the highest VT decreased Pa,CO2 from control (-0.5 +/- 0.3 kPa (-3.4 +/- 2.3 mmHg), p<0.05). In conclusion, this circuit effectively minimizes changes in alveolar ventilation and therefore arterial carbon dioxide tension during hyperpnoea.     

The Monogenic Scale-Space: A Unifying Approach to Phase-Based Image Processing in Scale-Space

In this paper we address the topics of scale-space and phase-based image processing in a unifying framework. In contrast to the common opinion, the Gaussian kernel is not the unique choice for a linear scale-space. Instead, we chose the Poisson kernel since it is closely related to the monogenic signal, a 2D generalization of the analytic signal, where the Riesz transform replaces the Hilbert transform. The Riesz transform itself yields the flux of the Poisson scale-space and the combination of flux and scale-space, the monogenic scale-space, provides the local features phase-vector and attenuation in scale-space. Under certain assumptions, the latter two again form a monogenic scale-space which gives deeper insight to low-level image processing. In particular, we discuss edge detection by a new approach to phase congruency and its relation to amplitude based methods, reconstruction from local amplitude and local phase, and the evaluation of the local frequency.     

FATIGUE BEHAVIOUR OF THREE VARIANTS OF THE ROLLER BEARING STEEL SAE 52100

Stress-controlled, low-cycle, push-pull fatigue tests were performed on three variants of the bearing steel SAE 52100 with slightly different compositions and heat treatments. The experiments demonstrated differences in the cyclic plastic behaviour of differently hardened steels (bainitically-hardened and martensitically-hardened, respectively), whereas the two martensitic variants, which differ in composition, behaved very similarly. Bainitically-hardened SAE 52100 steel exhibited initial hardening followed by cyclic softening above a stress amplitude level of 1200 MPa. In contrast, the martensitically-hardened variants showed a pronounced cyclic hardening. The deformation behaviour of the martensitically-hardened bearing steel in a monotonic tensile test and during the first cycles can be well understood on the basis of the transformation of retained austenite. This process leads to an onset of plastic deformation at lower stresses compared to the bainitically-hardened bearing steel. As a result of the subsequent cyclic hardening of the martensitic variants, the CSS curves are almost identical for the differently hardened conditions under investigation. Additional tests under pulsating compression documented that a high negative mean stress enhances the cyclic plasticity.     

In utero and lactational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces genital dysmorphogenesis in the female rat

Recently, Gray and Ostby (Toxicol. Appl. Pharmacol. 133, 285-294, 1995) reported that in utero and lactational TCDD exposure causes striking abnormalities in the rat female reproductive system, including reduced fecundity and vaginal threads. The mechanism by which TCDD induces such abnormalities is unknown. Thus, we sought to determine: (1) whether TCDD reduced fecundity by destroying ovarian follicles and (2) whether the vaginal threads resulted from a TCDD-induced developmental defect during embryogenesis or abnormal vaginal opening at puberty. Pregnant Holtzman rats were treated with 1.0 microgram TCDD/kg or vehicle by a single oral dose on gestation day (GD) 11, 15, or 18. Female offspring were monitored for vaginal opening and terminated on postnatal days 2, 21, and 42. The reproductive tract was removed and evaluated for structural abnormalities. The number of primordial follicles also was determined for each ovary. TCDD exposure on GD 11, 15, or 18 did not change the day of vaginal opening, affect ovarian morphology, or reduce the number of primordial follicles. However, this exposure induced the cleft clitoris and vaginal thread originally described by Gray and Ostby (1995) in approximately 55-96% and 36-44% of the litters in our study, respectively. Histologically the thread presented as a thick cord of mesenchyme surrounded by epithelial cells. This defect was clearly visible in histological sections at birth and was noted in the closed vaginas of prepubertal animals. These data suggest that in utero and lactational exposure to TCDD does not reduce the size of the primordial follicle pool; however, it induces developmental abnormalities in the vaginal canal.