Anhydrous Glycerol Research Articles

Comparison of Different Methods of Glycerol Preservation for Deep Anterior Lamellar Keratoplasty Eligible Corneas

To compare different methods of glycerol-preserved corneas intended for deep anterior lamellar keratoplasty (DALK). We analyzed transparency, transmittance, thickness, biomechanics, morphology, and antigenicity of donor corneas preserved by four different glycerol-based methods (n = 6 per group) for 3 months, as follows: tissues in anhydrous glycerol without aluminosilicate molecular sieves at room temperature (GRT); tissues in anhydrous glycerol with aluminosilicate molecular sieves at room temperature (SRT); tissues in anhydrous glycerol without aluminosilicate molecular sieves at -78°C (G78); and tissues in anhydrous glycerol without aluminosilicate molecular sieves at -20°C (G20). Slit lamp images and transmittance curves obtained by spectrophotometer show that the G78 cornea was the most transparent tissue. Stress-strain behavior indicated that corneas in the G78 group were the most pliable, and SRT corneas were the stiffest. Electron microscopy analysis indicated that corneal cytoarchitecture and keratocyte integrity was destroyed in all glycerol-preserved corneas. Disorganized stromal collagen fibers were evident in groups stored at RT. Especially in SRT corneas, parallelism was lost, fibrils were extremely tortuous and discontinuous, and widespread fibril degeneration could be found. Antigenicity of tissue, assessed via immunohistochemistry for CD45-positive cells, HLA-ABC and HLA-DR, was lowered after glycerol preservation relative to fresh cornea tissues, and immunoreactivity was located mainly on corneal epithelium and limbus rather than stroma. Anhydrous glycerol preservation without molecular sieves in a -78°C freezer was the best method to obtain DALK-eligible tissues that were both transparent and pliable.

Micro‐patterned drug delivery device for light‐activated drug release

The primary goal of this study was the fabrication, long-term stability, and measured release of a marker dye from a micro-patterned drug delivery device using (i) mechanical puncture and (ii) photodisruption with an ophthalmic Nd:YAG laser. A drug delivery device was made from a transparent bio-compatible polymer. The device consisted of two 2.6 mm diameter reservoirs containing 10% Na fluorescein dye. The device was implanted in the rabbit's eye (n = 2) with the cap of the device facing toward the exterior of the eye. Once the animals recovered from the implant surgery, 100% anhydrous glycerol was topically applied to the eye at the implantation site to decrease light scattering in the conjunctiva and sclera. The dye was released from one of the reservoir either using a 28 G ½ needle or an ophthalmic Q-switched Nd:YAG laser. A fluorescence spectrophotometer (FS) with fiber optic probe was used to measure the half-life of the dye in the eye. Measurements of fluorescence intensity were collected until the measurements return to baseline and histology was done on the tissue surrounded the device. None of the devices leaked of 10% Na fluorescein dye after implant. The ablation threshold of the drug delivery device was between 6 and 10 mJ to create 100-500 µm holes. The half-life measurement of the dye was found to be 13 days at the vitreous chamber after measuring the fluorescence intensity through the dilated cornea. Histology study showed minimal immune and foreign body response such as mild inflammation. This study established that the drug delivery device seemed to elicit minimal inflammatory response and retained its fluidic content until it was released with relatively longer retention time (half-life). Thus, similar device could be used for controlled release of drugs for certain ocular diseases.

Comparative Evaluation of Percutaneous Retrogasserian Glycerol Rhizolysis and Radiofrequency Thermocoagulation Techniques in the Management of Trigeminal Neuralgia

Among the percutaneous procedures for the treatment of trigeminal neuralgia, percutaneous anhydrous glycerol rhizolysis (PRGR) and radiofrequency (RF) ablation of trigeminal neuralgia have stood the test of time. A prospective study was conducted to compare PRGR and RF ablation techniques in patients with trigeminal neuralgia in terms of (1) efficacy of pain relief, (2) duration of pain relief and (3) side effects. All patients presenting to our pain clinic for the first time for the treatment of trigeminal neuralgia were enrolled to receive either PRGR or RF ablation; the treatment was chosen by the patient. Demographic data, magnetic resonance imaging scan, relevant medical disease, amount of anhydrous glycerol, lesion temperature, and total duration of RF were noted. The presence or absence of cerebrospinal fluid egress, immediate pain relief, duration of pain-free period, need for repeat injection or additional peripheral nerve block, and recurrence of pain were also noted. The degree of pain relief was recorded every 3 months. Any complications during the procedure and side effects were also recorded. Seventy-nine patients underwent either PRGR (n = 40) or RF thermocoagulation (n = 39). A total of 23 patients (58.9%) in the PRGR group and 33 patients (84.6%) in the RF group experienced excellent pain relief. The mean duration of excellent pain relief in the PRGR and RF groups was comparable. By the end of the study period, 39.1% patients in the PRGR group and 51.5% patients in the RF group experienced recurrence of pain. Both PRGR and RF techniques can achieve acceptable pain relief with minimal side effects.

Improvement of skin optical clearing efficacy by topical treatment of glycerol at different temperatures

In the past decades, laser has been widely used in clinical diagnosis and cosmetic therapy. However, there is limitation for further usage in deeper tissue for high scattering property. Skin optical clearing technique, by introducing optical clearing agents (OCAs) into tissue, will have a potential impact on optical diagnosis and therapy. In this work, anhydrous glycerol at different temperatures of 4, 25, 32 and 45°C were applied respectively to in vitro porcine skin, and reflectance and transmittance spectra were then measured dynamically using a spectrometry combined with integrating sphere system. Further, reduced scattering coefficient and penetration depth were obtained. Results showed that, glycerol at different temperatures could induce the reduced scattering coefficient of in vitro skin to decrease and the penetration depth to increase. 4 and 25°C glycerol had similar effect, decreasing the scattering by 48.2% and 49.7%, and increasing penetration depth by 37.9% and 39.5%, respectively. However, 32 and 45°C glycerol treatment could decrease scattering by 61.6% and 76.6%, and increase penetration depth by 53.3% and 84.1%, respectively. In conclusion, glycerol at higher temperature can induce greater and faster skin optical clearing efficacy.

Revealing the solid-like nature of glycerol at ambient temperature

We report on new dynamic measurements indicating a low frequency solid-like behaviour far above the glass transition and above the melting point in glycerol. Several tens micron thicknesses of pure (anhydrous) glycerol are deposited on highly wetting substrates. The response of the material to a mechanical stress is probed at room temperature as a function of the time and the frequency. The first type of experiment consists in measuring the linear dynamic response in a frequency range from 0.1 up to 10 rad/s. The second type of experiment consists in measuring the stress relaxation under a weak constant shear stress. In both cases, these independent experiments reveal that the glycerol exhibits a non-vanishing shear elasticity indicating a macroscopic solid-like character above its melting point. These results are compared with recent important observations reported, in particular, in the liquid state of glycerol by dielectric relaxation and in its supercooled states using low stress rheology.

Perfusion in hamster skin treated with glycerol

The objective of this article is to quantify the effect of hyper-osmotic agent (glycerol) on blood velocity in hamster skin blood vessels measured with a dynamic imaging technique, laser speckle contrast imaging (LSCI). In this study a dorsal skin-flap window was implanted on the hamster skin. The hyper-osmotic drug, that is, glycerol was delivered to the skin through the open dermal end of the window model. A two-dimensional map of blood flow of skin blood vessels was obtained from the speckle contrast (SC) images. Preliminary studies demonstrated that hyper-osmotic agents such as glycerol not only make tissue temporarily transparent, but also reduce blood flow. The blood perfusion was measured every 3 minutes for 36-66 minutes after diffusion of anhydrous glycerol. Blood flow in small capillaries was found to be reduced significantly within 3-9 minutes. Blood flow in larger blood vessels (i.e., all arteries and veins) decreased over time and some veins had significantly reduced blood flow within 36 minutes. At 24 hours, there was a further reduction in capillary blood perfusion whereas larger blood vessels regained flow compared to an hour after initial application of glycerol. Blood flow velocity and vessel diameter of the micro-vasculatures of hamster skin were reduced by the application of 100% anhydrous glycerol. At 24 hours, capillary perfusion remained depressed.

Does Egress of Cerebrospinal Fluid During Percutaneous Retrogasserian Glycerol Rhizotomy Influence Long Term Pain Relief?

To examine the effect of cerebrospinal fluid (CSF) flow during percutaneous retrogasserian glycerol rhizotomy (PRGR) on long term pain relief in patients with trigeminal neuralgia. Eighty-nine patients with trigeminal neuralgia underwent 102 PRGR procedures. PRGR was conducted under fluoroscopy. After the egress of CSF, anhydrous glycerol (0.3-0.4 cc) was injected in the sitting position. In the absence of CSF flow, 0.25 mL 2% lidocaine was injected to elicit hypesthesia in the affected side. Once hypesthesia was elicited glycerol was injected. Patients were grouped as A (CSF flow present) or B (CSF flow absent), according to the egress of CSF at the time of needle placement. Patients were followed up for the recurrence of pain (average duration of follow up, 62 months). CSF flow was present in 54 patients (60.6%) and absent in 35 patients (39.4%). Thirty patients (56.6%) of group A had excellent pain relief, 18 patients (33.3%) had good pain relief, and 6 patients (11.1%) had no pain relief. However, in the absence of CSF flow, 14 patients (40%) each had excellent and good pain relief, and 7 patients (20%) were treatment failures. The pain relief was comparable between the groups. The median time to recurrence of pain needing further injection was 66 months in group A and 63 months in group B (not significant). Presence of CSF flow during needle placement does not influence the success rate and duration of pain relief following PRGR.

Production of monoolein from oleic acid and glycerol in supercritical carbon dioxide media: A kinetic approach

Esterification of free fatty acids (FFA) with glycerol in supercritical carbon dioxide (SC-CO 2) media to produce designer monoacylglycerols (MAG) for food, cosmetic, and pharmaceutical industries, was conducted to elucidate the reaction kinetics and provide the reaction mechanism. Reactions were conducted in SC-CO 2 at 10–30 MPa, 170–250 °C in a batch stirred reactor using an anhydrous glycerol to oleic acid initial molar ratio (gly/oleic) of 10:1, 1:1 and 1:2 and in supercritical nitrogen at 10 MPa and 250 °C using 10:1 gly/oleic. Samples were collected as a function of time and MAG, diacylglycerol, triacylglycerol and FFA concentrations were determined using thin layer chromatography–flame ionization detection. The rate of MAG formation at 50% of equilibrium concentrations (Rate-50%) increased significantly ( p ≤ 0.05) with temperature but was not affected by pressure or supercritical media ( p > 0.05). Rate-50% values for 10:1 and 1:1 gly/oleic were similar ( p > 0.05) but higher ( p ≤ 0.05) than that for 1:2 gly/oleic. Equilibrium concentration of MAG significantly ( p ≤ 0.05) decreased with decreased initial glycerol concentration. The calculated rate constants provided a better understanding of the mechanism and are essential for optimal process design.

Genome size of plant-parasitic nematodes

tion. Representative specimens from the samples of each species were handpicked, fixed in hot 4% formaldehyde, transferred to anhydrous glycerol and mounted on Cobb slides to confirm identification. Morphology and morphometrics of specimens were compared to information in the literature and/or direct observations on reference material in collections. Haploid genome sizes and standard deviations are shown in Table 1. For seven taxa, standard deviations were less than 10% of the corresponding genome size; for two, they were between 15 and 20% and about 40% for Hemicycliophora conida. With the exception of Pratylenchus coffeae (very small genome and small standard deviation), the lack of precision in measurements tended to increase with decreasing genome size, implying that the technical limitation of the flow cytometry approach for determining genome size is reached with some genomes of plantparasitic nematodes. However, it was possible to provide, with confidence, the records for the genome sizes of seven plant-parasitic nematodes and, with adequate confidence, for two more. With this level of accuracy, it was also possible to confirm significant differences in sizes between different genera within the same family and subfamily. For example, the Nagelus obscurus genome size was found to be twice as large as that of Neodolichorhynchus lamelliferus, and of T. graciliformis (both belong to the same family as N. obscurus), and of Merlinius brevidens (same subfamily as N. obscurus). Polyploidisation events as mentioned by Gregory (2005) between congeneric species may explain such differences between closely related genera.

Interrelationship between the viscoelastic properties and effective moisture diffusivity of emulsions with the water vapor permeability of edible films stabilized by mesquite gum–chitosan complexes

White mineral oil-in-water emulsions (WMOE) with a dispersed phase volume fraction of 0.2 were stabilized with different ratios of the oppositely charged polyelectrolytes mesquite gum (MG) and chitosan (C), which interacted electrostatically. A higher proportion of C in the biopolymer blend increased the pH, mean volume average droplet diameter ( d 30), and the storage ( G′) and loss ( G″) moduli of the WMOE ( G′ being always larger than G″). The rate of droplet coalescence ( K c) of the emulsions incorporating C was first-order of magnitude lower (10 −8 s −1) than that of the WMOE made with only MG (10 −7 s −1). The WMOE exhibiting highest G′ and G″ was that made up with 10% MG–0.6% C ( E 10MG–0.6C) and was modified by adding anhydrous glycerol (AG) and/or candelilla wax (CW) to the continuous and/or dispersed phases, respectively. All the modified emulsions (ME) exhibited lower d 30 over time than E 10MG–0.6C. K c of all the ME had a magnitude of 10 −8 s −1. The ME exhibiting highest G′ and G″ values was that whose dispersed phase was modified with CW. In all the ME, G′ and G″ remained quite stable over time. The activation energy of the ME was determined in order to evaluate the difficulty of water to diffuse through the films biopolymer matrix. The emulsions where the continuous phase or the dispersed phase (not both) was modified exhibited significantly higher E a, and these emulsions also exhibited lowest water vapor permeability (WPV).

Same axonal regeneration rate after different endoneurial response to intraneural glycerol and phenol injection.

Glycerol (an atoxic alcohol) and phenol (a toxic monohydroxybenzene) are currently used as neurolytic blocking agents to relieve pain or spasticity. In the present study we compared the endoneurial response of anhydrous glycerol and 7% phenol-aqua after intraneural injection into rat sciatic nerve, using electron microscopy and immunohistochemical stainings. Despite the wide use of these drugs, a systematic morphological study of their action has not been done. Electron microscope studies showed different patterns of nerve damage for glycerol and phenol. Glycerol injection resulted in gross sciatic nerve injury, with myelin fragments widely dispersed in the endoneurium 1-2 weeks after the injury. Phenol-aqua injection resulted in gross sciatic nerve injury with focal haemorrhagic necrosis; nerve fibres were segmentally dissolved 1-2 weeks after the injury. In both groups the first axonal sprouts appeared in the area of the lesion 2 weeks after the injury and the sprouts became myelinated in both groups by 4 weeks. Immunohistochemical staining showed that in the glycerol-treated nerves macrophages were widely scattered in the endoneurium by day 3; the number of macrophages proximal to the lesion site and at the lesion site was significantly higher in the glycerol-treated nerves than in the phenol-treated nerves both at days 3 and 7. In the phenol-treated nerves, macrophages appeared after 1 week and they exceeded the number of macrophages in the glycerol-treated nerves at 2 weeks. The number of Schwann cells remained low until 4 weeks in both groups. The results show that glycerol-induced nerve fibre damage with breaching of myelin fragments is followed by invasion of macrophages into the endoneurium after 3 days. The delayed invasion of macrophages after phenol injection may be due to occluded vessels or may be related to the denaturing effect of phenol on the proteins needed for macrophage attraction. Despite the rapid invasion of macrophages after glycerol injection axonal regeneration was delayed when compared to that seen after traumatic axotomy, but the axonal regeneration occurred at the same time in both experimental groups. Thus, the results suggest that after chemical axonotmesis the axonal regeneration rate is not dependent on the macrophage invasion rate alone and that other endoneurial changes also play a role.

Spectrally- and time-resolved fluorescence emission of indole during solvent relaxation: a quantitative model

Relaxation of polar solvents around excited fluorescent solutes results in a continuous time-dependent red shift in the fluorescence spectrum. Static heterogeneous broadening can also produce time-variant fluorescence spectra. The two effects can be distinguished by a quantitative model of fluorescence during homogeneous electrostatic relaxation. The model describes the evolution of the instantaneous spectrum and the time variation of the intensity observed at any fixed wavelength. The model is in good agreement with the experimental data obtained using a solution of indole in anhydrous glycerol at 4 nm spectral and 65 ps temporal resolution.

Calorimetric evidence for a native-like conformation of hen egg-white lysozyme dissolved in glycerol

Hen egg-white lysozyme, lyophilized from aqueous solutions of different pH (from pH 2.5 to 10.0) and then dissolved in water and in anhydrous glycerol, has been studied by high-sensitivity differential scanning microcalorimetry over the temperature range from 10 to 150°C. All lysozyme samples exhibit a cooperative conformational transition in both solvents occurring between 10 and 100°C. The transition temperatures in glycerol are similar to those in water at the corresponding pHs. The transition enthalpies in glycerol are substantially lower than in water but follow similar pH dependences. The transition heat capacity increment in glycerol does not depend on the pH and is 1.25±0.31 kJ mol −1 K −1, which is less than one fifth of that in water (6.72±0.23 kJ mol −1 K −1). The thermal transition in glycerol is reversible and equilibrium, as demonstrated for the pH 8.0 sample, and follows the classical two-state mechanism. In contrast to lysozyme in water, the protein dissolved in glycerol undergoes an additional, irreversible cooperative transition with a marginal endothermic heat effect at temperatures of 120–130°C. The transition temperature of this second transition increases with the heating rate which is characteristic of kinetically controlled processes. Thermodynamic analysis of the calorimetric data reveals that the stability of the folded conformation of lysozyme in glycerol is similar to that in water at 20–80°C but exceeds it at lower and higher temperatures. It is hypothesized that the thermal unfolding in glycerol follows the scheme: N⇔ho-MG⇒U, where N is a native-like conformation, ho-MG is a highly ordered molten globule state, and U is the unfolded state of the protein.

The endoneurial response to neurolytic agents is highly dependent on the mode of application

Background and Objectives. The variability and predictability of neurolytic neural blocks were studied using an experimental rat sciatic nerve model. The goal of the study was to compare endoneurial and clinical responses to commonly used neurolytic agents. Methods. The sciatic nerves of 80 rats were treated either with intra- or perineural injections of 7% phenol-aqua, anhydrous glycerol, or 5% phenol-glycerol. Lidocaine and saline injections were used as controls. Muscle function and trophic changes of the hind limbs were evaluated, and samples for morphologic analysis were taken 1, 2, 4, and 8 weeks after the injections. Results. Intra- and perineural injections of 7% phenol-aqua resulted in gross endoneural damage of the sciatic nerve and hind limb paresis. Perineural 5% phenol-glycerol and anhydrous glycerol injections caused subperineural damage with slight paresis; gross endoneural damage and noticeable paresis were present only after intraneural injections. When 7% phenol-aqua was compared to other neurolytic agents, the differences in the lesion size ( P < .0001) were statistically significant after perineural injections. Regeneration occurred in a stereotypic fashion in all neurolytic groups. Axonal sprouts were noted at the injured area 2 weeks after intraneural and 1 week after perineural injections. Motor function had partially recovered at 8 weeks. Conclusion. There were no differences in the effects of clinically used neurolytic agents after intraneural injections. Although the perineurally applied 7% phenol-aqua induced marked endoneural damage, the destructive effect of glycerol and phenol-glycerol injections seemed to be prevented by the perineurium; phenol-glycerol and glycerol treatments induced subperineural damage only after perineural injections. The ability to penetrate the perineurium favors the use of 7% phenol-aqua in peripheral perineural blocks when complete neurolysis is the goal.

Lipase-catalyzed esterification of glycerol with n-3 polyunsaturated fatty acids from winterized fish oil Esterificación catalítica de glicerol con ácidos grasos 3-n poliinsaturados de aceite de pescado

Menhaden oil was hydrolyzed using a lipase from Pseudomonas sp. The hydrolysate was cold frac tionated at-72°C. Glyceride synthesis was performed using the same lipase under different reaction environments. The best conditions for the esterification reaction were 39 °C for 18 h in a reaction mixture containing anhydrous glycerol, n-3 polyunsaturated fatty acids (PUFA) enriched solution (2% lipids in hexane), hexane, and phosphate buffer-lipase solution (1% w/v). Product composition was 81.33% triacylglycerides and 18.67% of free fatty acids (w/w). Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) accounted for 36.18% of the esterified fatty acids, of which 58% was EPA and 42% was DHA. This method offers an alternative to produce glycerides rich in n-3 PUFA.

Glycerol gangliotomy of the second dorsal cervical root in rats: an experimental study to evaluate a minimal invasive approach for the treatment of the chronic cervicogenic headache.

Glycerol is a known agent in the therapy of chronic tic douloureux. It has been used for about 20 years in percutaneous, retrogasserian minimal-invasive rhizotomy, although the pharmacological mechanism of the pain relief involved remains unclear. To investigate glycerol treatment as a possible replacement for invasive approaches in the therapy of chronic cervicogenic headaches, we performed an experimental study on the pathomorphologic action of anhydrous glycerol injection into the second upper cervical dorsal root ganglion (DRG) of rats. Glycerol injections into the second cervical ganglion were investigated light- and electron-microscopically in a series of 40 rats for survival times of up to 30 days. We detected an unspecific overall effect on sensory neurons and satellite cells, as well as on myelinated and unmyelinated axons and Schwann cells. This could be detected after 5 days and sometimes led to degeneration of most of the neurons. Contralateral saline injections as a control showed no morphological effects. The loss of afferent fiber connections to the posterior horn of the myelon could be detected by immunohistochemical labeling of reactive astrocytes. Our results show a glycerol-induced deterioration of the cytoarchitecture of the neurons and their glial satellite cells. The effects on the ganglion cells appear to have been mediated by membrane disturbances and loss of glial integrity. These observations are contrary to previously reported results indicating the specific effect of glycerol on thin myelinated sensory axons.

Blocks of the foramen rotundum and the oval foramen: a reappraisal of extraoral maxillary and mandibular nerve injections.

To present our experience of regional anaesthesia with blocks of the foramen rotundum and the oval foramen. Open study. University Hospital, Beograd, Yugoslavia. 107 patients who underwent 58 maxillary and 49 mandibular nerve blocks. Injection of 2% lignocaine with adrenaline 1/80,000 with an 18 G venflon or 20 G spinal needle. Quality of anaesthesia and morbidity. 49 of the 58 maxillary (84%) and 45 of the 49 mandibular (92%) nerve blocks were successful (no sensitivity to pinprick in the distribution of the injected nerve and a painless operation). There were 17 complications (26%), 8 in the maxillary and 9 in the mandibular group. All complications were minor and transient, and 6 could be attributed to anhydrous glycerol rather than the injection technique itself. Blocks of the foramen rotundum and the oval foramen achieve good regional anaesthesia in the maxillofacial region.

Structural changes in thylakoid membranes of chilling-resistant and sensitive plants after heating and glycerol dehydration as revealed by 31P NMR and electron microscopy

31P NMR spectra demonstrated that the chemical shift anisotropy of chilling-resistant peas and spinach thylakoid membranes is 110 ppm, whereas that for chilling-sensitive tomato membranes is 150–160 ppm. These data suggest different mobilities of membrane phospholipid orthophosphate moieties. When the samples of thylakoid membranes were heated (35–50°C) or incubated in an anhydrous glycerol (at 20°C) the chemical shift anisotropy gradually decreased to a level (20–40 ppm) which is an inherent feature of all model lipid systems (Cullis et al., in: Phospholipids and Cellular Regulation, Vol. 1, Structural properties and functional role of phospholipids in biological membranes, ed. J.F. Kul (CRC Press Inc., Boca Raton) p. 1). Electron microscopy of the same samples has revealed that these dynamic changes were accompanied by reorganization of membrane structure as evidenced by the alteration of size and distribution of IMPs on the EF fracture faces, the appearance of polymorphic structures and the disturbance of intramembrane grana contacts. Elevation of temperature during glycerol embedding similarly resulted in increased structural changes. We believe that both temperature and glycerol can induce similar disturbance of grana intramembrane interactions, as well as affect intermolecular bonds within membrane interface regions. The structural aspects of the thylakoid membranes are briefly discussed.

Ultrastructural morphology and allergen detection in birch pollen after aqueous, anhydrous-liquid, and vapor fixation techniques.

In order to find a good compromise between preservation of ultrastructural morphology and retention of antigenicity, birch pollen grains were chemically fixed in aqueous p-formaldehyde or glutaraldehyde, in p-formaldehyde or glutaraldehyde dissolved in anhydrous glycerol, and in p-formaldehyde or glutaraldehyde vapor. Representative cytoplasmic areas were inspected for the preservation of ultrastructural morphology and for their capacity to bind a monoclonal antibody against Bet v I, the major birch pollen allergen. The experiments showed that cytoplasmic morphology was best preserved after vapor fixation in p-formaldehyde. This fixation also led to the highest degree of specific antibody binding.

Glycerol injection to the rat trigeminal nerve: histological and immunohistochemical studies.

The effect of topical glycerol injection into the rat trigeminal nerves was investigated histologically and immunohistochemically. Anhydrous glycerol was injected into the preganglionic portion of the trigeminal nerves via a ventral approach. Extensive myelin swelling and axonolysis were observed in the rats killed 1 and 2 weeks after glycerol injection. Numerous inflammatory cells were seen especially in the animals sacrificed 1 week after surgery. Myelin disintegration continued up to 4 weeks after glycerol injection. In normal and saline injected sham operated nerves, calcitonin gene-related peptide (CGRP)- and substance P(SP)-like immunoreactivities were densely localized in the nerve fibers. A marked decrease in both CGRP- and SP-like immunofluorescence was seen in the nerves after glycerol injection. The remaining nerve fibers often had blunt endings with increased fluorescence. Swollen and winding structures were also found. These immunohistochemical changes were observed in the rats killed 1 and 2 weeks following surgery. A similar change but of lesser degree was seen in the 4-week-animal. The present study suggests that topical glycerol injection into the trigeminal nerve induces degeneration of the nerves immunoreactive to CGRP and SP. These changes emphasize the putative functional implications of the peptides in relieving the pain of trigeminal neuralgia after topical glycerol injection.