In vivo noninvasive determination of abnormal water diffusion in the rat brain studied in an animal model for multiple sclerosis by diffusion-weighted NMR imaging.

In vivo NMR images of the rat brain were obtained using a NMR microscope (7 T) from SMIS (England). Four animals were imaged every 3-4 days during a pathological cycle (starting after induction and up to 37 days) of experimental allergic encephalomyelitis (EAE), an animal model for multiple sclerosis. The EAE rats were weighted and clinically scored daily. We aimed at measuring the apparent diffusion coefficient (ADC) or the mean diffusivity (D) with a high accuracy, and within a reasonable experimental time frame, because of the clinical situation of the animals. Therefore, we fitted the ADC value from five diffusion-weighted images--with an experimental time of 17 min/image--and chose to apply diffusion-sensitizing gradients in a direction intersecting all fiber directions of the external capsule. With this, we also obtained high b-values. For the control rats, we obtained a statistical mean value of ADC = (388 +/- 16) 10(-12) m2/s for gray matter and a statistical mean value of (D) of (750 +/- 30) 10(-12) m2/s for white matter, measured in the external capsule. For the EAE rats, no alterations in ADC values of gray matter with increasing clinical scores were observed. Concerning white matter, as determined in the external capsule, there were no significant differences in (D) values between controls and EAE rats before clinical signs occurred. However, when clinical signs were observed, we could demonstrate a significant positive correlation between the clinical score and the (D) values in the external capsule. As the clinical signs became more severe, we measured a rise in water diffusion (increase in (D)) in the external capsule, which was accompanied by the occurrence of interstitial edema as revealed by a complementary histological study.

Degranulation of rat salivary glands following treatment with receptor-selective agonists.

1. The aim of this study was to find a drug that induces an almost complete degranulation of secretory cells in rat parotid and submandibular glands. 2. Phenylephrine (alpha-adrenergic), isoproterenol (beta-adrenergic) and mecholine (muscarinic cholinergic) were tested. Time and degree of maximal depletion of acinar and granular convoluted tubule cells were determined morphologically. 3. Following phenylephrine-injection (5 mg/kg or 10.2 mg/kg, i.p.), no effect on the acinar granulation level was observed in either of the glands, while about 50-60% granular convoluted tubules were degranulated for at least 120-180 min post-injection. 4. With isoproterenol (5, 10, 40, 70 or 100 mg/kg, i.p.), degranulation of 100% of the acinar cells in the parotid and 80% of the acinar cells in the submandibular gland was observed 90 min post-injection. Granular convoluted tubule cells did not respond to this beta-adrenergic drug. 5. Mecholine (3.75 or 7.5 mg/kg, i.p.) induced mainly degranulation of granular convoluted tubule cells (about 50% after 120 min). Numbers of granulated acinar cells decreased only slightly in both glands (about 10%, 90-120 min). 6. From this study it appears that with a relatively low dosage (5 mg/kg, i.p.) of isoproterenol, a high level of degranulation can be induced in acinar cells of rat parotid and submandibular glands without toxic side effects. Concerning granular convoluted tubules, only moderate degranulation was observed with phenylephrine and mecholine, respectively.

A study of multiple sclerosis patients with magnetic resonance spectroscopic imaging.

Eleven patients with clinically definite MS and three healthy controls were investigated by magnetic resonance spectroscopic imaging. The data sets were analysed for all voxels containing white matter only. We classify these voxels in healthy controls as normal white matter (NWM), and in MS patients as normal-appearing white matter unaffected by MS lesions (NAWM) or white matter affected by MS lesions. The spectra belonging to the voxels were analysed for content of cholines, creatines and N-acetylaspartate (NAA), and compared as a group. It was found that lesions differ from white matter in chemical composition and, moreover, that normal-appearing white matter differs from healthy white matter. Specifically, levels of NAA are lower in patients. There seems to be a linear relation between the composition of white matter and the expanded disability status scale value for the patient. The presence of lactate could not be established, and no unambiguous differences were found between patients with relapsing-remitting and relapsing-progressive disease.

The role of secretory granules in radiation-induced dysfunction of rat salivary glands.

To investigate the possible role of secretory granules in radiation-induced salivary gland dysfunction, rats were pretreated with isoproterenol (5 mg/kg intraperitoneally) to degranulate salivary gland acini. At maximal depletion, salivary glands were locally irradiated with a single dose of 15 Gy of X rays. Parotid and submandibular/sublingual saliva samples were collected before and 1-10 days after irradiation. The lag phase, flow rate, concentrations of potassium and sodium, and amylase secretion were determined. Sham-treated, isoproterenol-treated and irradiated animals provided reference data. In the parotid gland, but not in the submandibular gland, protection against radiation-induced changes in flow rate and composition of saliva occurred after pretreatment with isoproterenol. Combining morphological data from a previous study with data from the current study, it is suggested that improvement of parotid gland function is attributed predominantly to a proliferative stimulus on acinar cells by isoproterenol and not to its degranulation effect. After pretreatment with isoproterenol, an earlier expression of radiation-induced acinar cell damage leading to death was observed, followed by a faster tissue recovery. Thus the proliferative stimulus on acinar cells may accelerate the unmasking of latent lethal damage, resulting in the earlier replacement of dead cells by new, functionally intact cells.

The role of secretory granules in the radiosensitivity of rat salivary gland acini--a morphological study.

The aim of this study was to investigate the radiosensitivity of salivary gland tissue pretreated with isoproterenol to establish a status of depletion of secretory granules in acinar cells at the time of irradiation. Nuclear aberrations and cell lysis were taken as parameters for cell death. Local X irradiation with a single dose of 15 Gy induced comparable early morphological changes in the rat parotid and submandibular glands. During the first day after irradiation, the most obvious changes were degranulation of serous cells and induction of nuclear aberrations in both the secretory (serous as well as mucous) and intercalated duct compartment. Subsequently, progressive lysis occurred in secretory units but not in intercalated and striated ducts. Recovery of tissue integrity was observed from day 6. Early radiation-induced cell death was not reduced by isoproterenol-induced degranulation of acinar cells before irradiation. Subsequent recovery from radiation damage seemed to occur earlier in parotid glands but not in submandibular glands pretreated with isoproterenol. From the present study it is concluded that the radiosensitivity of serous salivary gland acini is not dependent on the presence of secretory granules at the time of irradiation. There was some evidence for a faster recovery from radiation damage observed after pretreatment with isoproterenol which may be the result of drug-induced stimulation of cell proliferation.

Radiation-induced cell proliferation in the parotid and submandibular glands of the rat.

Repopulation of tissues with cells at damaged sites is an important feature in the recovery of radiation-induced tissue injury. To obtain insight into the regenerative process in salivary gland tissue, proliferative activity was measured as a function of time in the different epithelial cell compartments of rat parotid and submandibular glands after local X irradiation with a single dose of 15 Gy. Bromodeoxyuridine-labeling indices were determined before and 10 h and 1, 3, 6, 10, 15, 20 and 30 days after irradiation. In both glands, X irradiation caused cell death and cell cycle delay manifested during the first day. Three days after irradiation, cell proliferation started in the intercalated duct. Six days after irradiation, proliferation was also observed in acinar and granular convoluted tubule cells. The striated ducts showed proliferative activity starting at day 6 (parotid) and day 10 (submandibular), respectively. The results of this study suggest that after 15 Gy of X rays repopulation takes place in all cell compartments. From the present study it cannot deduce if these cells are originating solely from progenitor cells residing in the intercalated duct or if cells of the other compartments are also stimulated. Proliferative activity was found to be higher in the intercalated duct compartment of the parotid gland than of the submandibular gland, which may be related to the suggested greater radiosensitivity and thus a greater demand for cell replenishment in the parotid gland.

In vitro NMR micro imaging of the spinal cord of chronic relapsing EAE rats.

Chronic relapsing experimental allergic encephalomyelitis (Cr-EAE) was induced in Lewis rats with an emulsion of guinea pig spinal cord tissue in complete Freund's adjuvant enriched with Mycobacterium tuberculosis H37 RA. The sensitized rats developed Cr-EAE showing two to three relapses during the first 40 days. In vitro transverse T2-weighted spin echo images of the spinal cord of Cr-EAE rats, sacrificed at the clinical height (hind leg paralysis and urinary incontinence) of the third bout and their controls, were compared with the corresponding histopathology. Lesions extended over the entire spinal cord, however, the larger lesions were predominantly present in the cervical and upper thoracic regions. In the white matter only areas of demyelination and large perivascular demyelination were discernable on the MR images. Size and shape of these lesions correlated well with the morphological characteristics revealed by histopathology. Plaques in the ventrolateral funiculus were generally located peripherally, while plaques in the dorsal funiculus were mainly present in the medial part. The NMR images, however, could not distinguish between demyelination, remyelination, inflammation, and oedema. Also lesions in the gray matter could not be distinguished with MR imaging techniques. However, if lesions were localized at the interface of the gray and white matter the boundary between the gray and white matter was less well defined.

Mucin-containing lozenges in the treatment of intraoral problems associated with Sjögren's syndrome. A double-blind crossover study in 42 patients.

Irreversible hyposalivation is a common sequela of Sjögren's syndrome and may lead to a decreased quality of the patient's life. The aim of this study was to evaluate the efficacy and therapeutic value of mucin-containing lozenges in reducing patients' complaints of hyposalivation. In a double-blind crossover trial in 42 patients with Sjögren's syndrome, the efficacy and therapeutic value of both a mucin-containing and placebo lozenge were assessed by means of self-administered questionnaires, which had to be completed before and after the use of each type of lozenge for a period of 2 weeks. Seventy-six percent of the patients preferred the mucin lozenge, 10% preferred the placebo, and 14% had no preference. In reducing patients' complaints, sucking the mucin lozenge resulted in a larger improvement of the total pattern of complaints and the sensation of oral dryness, and in a longer moistening of the oral cavity than the placebo. Oral functioning was improved after the use of the placebo, and the patients reported the taste of the placebo to be better than the mucin lozenge. From the responses it was concluded that the use of the mucin lozenges can be recommended in the treatment of oral symptoms of xerostomia.

[MRI and MRS diagnosis. Application in multiple sclerosis patients and research animals with experimental allergic encephalomyelitis]. / MRI- en MRS-onderzoek. Toepassing bij patiënten met multipele sclerose en proefdieren met experimentele allergische encephalomyelitis.

MR imaging and spectroscopy offer a noninvasive way to observe lesions and biochemical changes, respectively, that may provide new insights into demyelinating diseases such as MS. Although the role and importance of some of the metabolites, such as choline and N-acetyl aspartate in brain function and disease are not fully understood, the specificity of these changes may provide information about the stage and reversibility of the brain lesions. Animal studies are particularly insightful when MR spectroscopic signals are correlated with histologic and biochemical techniques. Clinical application of spectroscopic imaging could arise from the capability to differentiate between early lesions that might respond to therapy and older irreversible lesions. Although more data need to be obtained, MR spectroscopy shows promise for monitoring progression of MS and evaluating therapy.

Xerostomia : overview and feasible management conducive for Tanzanie [sic] and other developing countries

Saliva makes an important and varied contribution to the efficient working and protection of the human body. Reduced salivary secretion; a condition which can be observed in a lot of diseases and physiological conditions; results in a wide scale of complaints such as a dry and burning sensation of the mouth; difficulties with chewing; swallowing and speech; nocturnal oral discomfort; impeded social activities; rampant caries and frequently occuring oral infections. In this review the most important causes and consequences are discussed as well as some of the remedies currently used to treat these patients. Special attention is given to feasible management of these patients for Tanzania and other developing countries

Staining myelin and myelin-like degradation products in the spinal cords of chronic experimental allergic encephalomyelitis (Cr-EAE) rats using Sudan black B staining of glycol methacrylate-embedded material.

A high-resolution light-microscopical (HRLM) technique is described to visualize myelin, and macrophages containing degradation products of myelin, in the spinal cords of chronic relapsing experimental allergic encephalomyelitis (Cr-EAE) rats. This HRLM technique was developed to optimalize the correlation between nuclear magnetic resonance (NMR) characteristics and histopathological images in this well-established animal model for multiple sclerosis (MS). Spinal cords were fixed by perfusion with a combination of cacodylate-buffered glutaraldehyde and formaldehyde, post-fixed in Dalton's fixative (containing osmium tetroxide), rinsed in water, processed in ethanol, acetone, and embedded in glycol methacrylate resin (Technovit 7100/HistoResin). Semi-thin sections were stained with Sudan Black B and counterstained with Cresyl Fast Violet, resulting in black staining of myelin and its degradation products, with blue/violet staining of demyelinated axons and other tissue elements. These dyes were selected with the aid of a numerical model of staining, which took both access and lipophilicity into account. The staining procedure is simple and highly reproducible. The resulting images are contrast rich, and combine excellent morphology with a high degree of lipid retention.

Protocol for the prevention and treatment of oral sequelae resulting from head and neck radiation therapy.

In addition to the desired antitumor effects, head and neck radiation therapy induces damage in normal tissues that may result in oral sequelae such as mucositis, hyposalivation, radiation caries, taste loss, trismus, soft-tissue necrosis, and osteoradionecrosis. These sequelae may be dose-limiting and have a tremendous effect on the patient's quality of life. Current policies to prevent these sequelae primarily are based on clinical experience and show great diversity. A protocol for the prevention and treatment of oral sequelae resulting from head and neck radiation therapy, based on fundamental research and data derived from the literature, is presented. The protocol is particularly applicable in centers with a dental team. This team should be involved at the time of initial diagnosis so that a successful preventive regimen is an integral part of the overall cancer treatment regimen.

[Xerostomia-related dental caries]. / Xerostomie-gerelateerde cariës.

The initiation and prevention of xerostomia-related dental caries were studied using an in situ model. The morphology of induced carious lesions was compared with that of natural xerostomia-related dental caries. Both natural and induced xerostomia-related dental caries showed the same patterns of decay. Using the in situ model three preventive procedures were tested: neutral F gel applied every second day or weekly, and a daily rinse with a fluoride mouthwash for a period of six weeks. Application of fluoride gel or the use of the fluoride mouthrinse resulted in significant inhibition of the demineralization process. Of the procedures evaluated fluoride gel applied every second day was the most effective in preventing the onset of xerostomia-related dental caries.

Management of the oral features of Sjögren's syndrome.

In this paper the basis of the oral features of Sjögren's syndrome is described and guidelines for proper management of these features are given. The most pronounced oral symptoms are a dry sensation in the mouth and difficulties with swallowing and speech. Furthermore, these patients do not sleep well and may complain about burning mucous membranes, rampant caries and candidosis. Rampant caries can be prevented by optimal oral hygiene and frequent applications of a fluoride gel. Prophylaxis of candidosis can be achieved by meticulous oral hygiene and removal of predisposing factors (e.g. poorly fitting dentures). It is only possible to treat the other oral signs of Sjögren's syndrome symptomatically, because damage of salivary-gland parenchyma is progressive and irreversible. In the early stages of Sjögren's syndrome, good results can be obtained by gustatory or pharmacological stimulation of the salivary secretion. In the more advanced stages, the patient has to resort to oral rinses and saliva substitutes, the majority of which are not satisfactory. Promising results have been obtained with mucin-containing lozenges.

Rheological aspects of mucin-containing solutions and saliva substitutes.

In this study rheological properties of aqueous solutions of mucin, albumin and mucin-albumin have been investigated in search for saliva substitutes. They were compared with commercially available saliva substitutes on the one hand and natural human saliva on the other hand. For the latter a few measurements on saliva are reported here in addition to previously reported measurements done in our laboratory. Proteins absorb at the interface and saliva proteins do so strongly and rapidly. Therefore rheological measurements were carried out on the interface and on the bulk underneath the layer. In both cases the flow curve and the complex viscosity was determined. The results show that specific mucin-albumin solutions were rheologically similar to human whole saliva with respect to both bulk liquid and surface properties. The rheological properties of commercial saliva substitutes were essentially different from those of human saliva. It is concluded that mucin-albumin solutions have good perspectives as saliva substitutes.

[Dry mouth; possible cause--pharmaceuticals]. / De droge mond. De mogelijk oorzakelijke rol van geneesmiddelen.

Many elderly complain about oral dryness. This complaint can be the result of the use of drugs, because many drugs, such as anti-depressives, anti-psychotics and anti-hypertensives, have an anti-cholinergic or anti-adrenergic action. Knowledge of this potential side-effect of drugs as well as adjustment of schedules of drug usage may result in (partly) relief of dryness-related complaints. In this paper first of all mechanisms that underly negative regulation of salivary secretion are discussed. An overview is given of drugs with an salivary secretion inhibitory action. In addition, suggestions are presented to manage drug-induced hyposalivation.

[Cause, effects and treatment of hyposalivation]. / Oorzaak, gevolg en behandeling van hyposialie.

Adverse effects of drugs, radiotherapeutic treatment of head and neck tumors and Sjögren's syndrome are common causes of hyposalivation. The resulting sequelae include oral dryness, burning mouth, impeded oral functions, nocturnal oral discomfort and an increased incidence of rampant caries and oral infections. Causal therapy is only occasionally applicable. The main causes, consequences and management of hyposalivation are described.

In vivo phosphorus magnetic resonance spectroscopy in multiple sclerosis.

Localized phosphorus magnetic resonance spectroscopy at 1.5 T was performed in 39 patients with multiple sclerosis and in 15 healthy controls. The multiple sclerosis spectra showed increased creatine phosphate levels. This increase was correlated with the severity of the handicap and was greater in patients with a progressive course of the disease than in patients with relapsing-remitting disease. No clear abnormalities were observed in the spectra of patients with multiple sclerosis regarding the phosphomonoesters, phosphodiesters, inorganic phosphate, and beta-adenosine triphosphate or with respect to pH values. There was an increased creatine phosphate level in the spectra in relation to a low metabolic state of the brain.

A survey of prevention and treatment regimens for oral sequelae resulting from head and neck radiotherapy used in Dutch radiotherapy institutes.

Radiation treatment plays an important role in the management of head and neck cancer. Unfortunately several radiation-induced side effects may occur including mucositis, hyposalivation, radiation caries, trismus and osteoradionecrosis. It is generally accepted that most side effects can be prevented or reduced in severity. The purpose of this investigation was to make a survey of the prevention and treatment regimens for oral sequelae resulting from head and neck radiotherapy applied in all radiotherapy institutes in the Netherlands, and to evaluate the differences in these regimens. In all Dutch centers (n = 20) in which irradiation of head and neck cancer patients is performed, members of the staff responsible for prevention and treatment of oral side effects were interviewed. Questions referred to composition of the dental team, screening and care pre-irradiation, care during irradiation, and care post-irradiation. There appeared to be a great diversity in the preventive approach of the head and neck cancer patient in Dutch radiotherapy institutes. The most comprehensive counseling was performed by those centers in which a dental team was active, particularly when an oral hygienist was a member of such a team. The diversity is among others based on lack of well-defined guidelines in many centers, the spread of a relatively small patient group over a rather large number of centers, absence of a dental team in some centers, absence of an oral hygienist in some dental teams, and the observation that a rather large number of patients were not referred, or not timely referred to the dental team. There seems to be a need for the development of a general protocol for the prevention of oral complications applicable in all centers.