Neurophysiology of swallowing.

Swallowing is a complex motor event that is difficult to investigate in man by neurophysiological experiments. For this reason, the characteristics of the brain stem pathways have been studied in experimental animals. However, the sequential and orderly activation of the swallowing muscles with the monitoring of the laryngeal excursion can be recorded during deglutition. Although influenced by the sensory and cortical inputs, the sequential muscle activation does not alter from the perioral muscles caudally to the cricopharyngeal sphincter muscle. This is one evidence for the existence of the central pattern generator for human swallowing. The brain stem swallowing network includes the nucleus tractus solitarius and nucleus ambiguus with the reticular formation linking synaptically to cranial motoneuron pools bilaterally. Under normal function, the brain stem swallowing network receives descending inputs from the cerebral cortex. The cortex may trigger deglutition and modulate the brain stem sequential activity. The voluntarily initiated pharyngeal swallow involves several cortical and subcortical pathways. The interactions of regions above the brain stem and the brain stem swallowing network is, at present, not fully understood, particularly in humans. Functional neuroimaging methods were recently introduced into the human swallowing research. It has been shown that volitional swallowing is represented in the multiple cortical regions bilaterally but asymmetrically. Cortical organisation of swallowing can be continuously changed by the continual modulatory ascending sensory input with descending motor output. Significance: Dysphagia is a severe symptom complex that can be life threatening in a considerable number of patients. Three-fourths of oropharyngeal dysphagia is caused by neurological diseases. Thus, the responsibility of the clinical neurologist and neurophysiologist in the care for the dysphagic patients is twofold. First, we should be more acquainted with the physiology of swallowing and its disorders, in order to care for the dysphagic patients successfully. Second, we need to evaluate the dysphagic problems objectively using practical electromyography methods for the patients' management. Cortical and subcortical functional imaging studies are also important to accumulate more data in order to get more information and in turn to develop new and effective treatment strategies for dysphagic patients.     

G Protein Mutations in Pituitary Tumors: A Study on Turkish Patients

Activating mutations of the G proteins, Gsalpha (gsp) and Gi2alpha (gip) have been reported in subsets of pituitary tumors. The objective of the study was to assess the frequency of gsp and gip mutations in pituitary tumors from Turkish patients and to investigate the possibility of mutations of protein kinase A catalytic subunit (PKAC) that activates the downstream effectors of adenylyl cyclase. PCR-amplified genomic DNA was analyzed for the presence of mutations in codons 201 and 227 of Gsalpha, codon 179 and 205 of Gi2alpha and codon 196 of PKAC, by single strand conformation polymorphism analysis, allele-specific oligonucleotide hybridization and DNA sequencing. Twenty-two patients from Turkey, 15 females and 7 males were investigated; 7 somatotroph adenomas, 7 clinically non-functioning tumors, 7 prolactinomas and 1 corticotroph adenoma. G protein mutations were identified in 6 of 22 (27.3%) pituitary tumors. Four tumors (3/7 somatotroph adenomas, 43%, 1/7 clinically non-functioning tumor) demonstrated gsp mutations at codon 201 arginine to cysteine and one recurrent somatotroph adenoma demonstrated a mutation of the Gi2alpha gene at codon 193 lysine to arginine. One tumor exhibited a C to T variation in the intervening sequence between codons 179 and 205 of the Gi2alpha gene. No mutations at codon 227 of Gsalpha, codons 179 and 205 of Gi2alpha and codon 196 of the PKAC gene were identified.     

Elevated plasma concentration of asymmetric dimethylarginine that is reduced by single dose testosterone administration in idiopathic hypogonadotropic hypogonadism patients

Our aim was to investigate whether plasma l-arginine and asymmetric dimethylarginine (ADMA) concentrations and nitric oxide (NO) production are altered in male idiopathic hypogonadotropic hypogonadism (IHH) patients in the hypogonadal state and after single dose testosterone administration compared with those in control subjects. Eighteen newly diagnosed male patients with IHH and 20 healthy volunteer controls matched by age and body mass index were enrolled in the study. Single dose testosterone was administrated im. Initially, pretreatment blood samples were collected after overnight fasting. Posttreatment blood samples were drawn 10 d after the injection. ADMA, l-arginine, and NO were measured in pre- and posttreatment blood samples. The pretreatment ADMA and l-arginine levels were significantly higher, and plasma nitrite plus nitrate (NOx) levels were lower than those in the control group. After 10 d of treatment, ADMA and l-arginine levels were significantly reduced, and NOx levels were significantly increased. There was a significant positive correlation (P < 0.01) between ADMA and l-arginine and a negative correlation between ADMA and NOx levels in patients and controls. In conclusion, the patients with IHH showed elevated plasma ADMA levels associated with a reduction in NO production. Single dose parenteral T administration lowered ADMA concentrations and increased NO production to the control group values.     

Protective effect of metronidazole on uncoupling mitochondrial oxidative phosphorylation induced by NSAID: a new mechanism

BACKGROUND: The pathogenesis of non-steroidal anti-inflammatory drug (NSAID) enteropathy is complex. It involves uncoupling of mitochondrial oxidative phosphorylation which alters the intercellular junction and increases intestinal permeability with consequent intestinal damage. Metronidazole diminishes the inflammation induced by indomethacin but the mechanisms remain speculative. A direct effect on luminal bacteria has traditionally been thought to account for the protective effect of metronidazole. However, a protective effect of metronidazole on mitochondrial oxidative phosphorylation has never been tested. AIMS: To assess the protective effect of metronidazole on mitochondrial uncoupling induced by indomethacin and also on the increased intestinal permeability and macroscopic damage. MATERIAL AND METHODS: The protective effect of metronidazole was evaluated in rats given indomethacin; a macroscopic score was devised to quantify intestinal lesions, and intestinal permeability was measured by means of (51)Cr-ethylenediaminetetraacetic acid. The protective effect of metronidazole against mitochondrial uncoupling induced by indomethacin was assessed using isolated coupled rat liver mitochondria obtained from rats pretreated with metronidazole or saline. RESULTS: Metronidazole significantly reduced the macroscopic intestinal damage and increase in intestinal permeability induced by indomethacin; furthermore, at the mitochondrial level, it significantly reduced the increase in oxygen consumption in state 4 induced by indomethacin and caused less reduction of the respiratory control rate. CONCLUSION: Our study confirmed the beneficial effects of metronidazole on intestinal damage and intestinal permeability, and demonstrated, for the first time, a direct protective effect of metronidazole on uncoupling of mitochondrial oxidative phosphorylation caused by NSAIDs.     

Re-eruption of an intruded immature permanent incisor with necrotic pulp: a case report

Intrusive luxation is a serious dental injury that causes damage to the pulp and supporting structures of a tooth because of its dislocation into the alveolar process. This paper presents the case of the re-eruption of a severely intruded immature permanent incisor with a crown-root fracture. A 9-year-old boy was referred to the clinic 1 day after a fall. Clinical and radiographic examinations revealed intrusive luxation of the immature left permanent incisor and a crown-root fracture without pulp exposure. Palatal gingivectomy was done 2 weeks later to facilitate re-eruption. Root canal therapy with intracanal calcium hydroxide paste was initiated during the first month owing to severe spontaneous pain. Six months later, the tooth re-erupted to a normal position, after which root canal obturation and a final esthetic restoration were done. The present case demonstrates the possibility of obtaining re-eruption of intruded immature permanent teeth with interim medication (calcium hydroxide) in the root canal.     

An unusual case of primary colonic dedifferentiated liposarcoma

INTRODUCTION

İn this paper, we present a rare case of primary dedifferantiated liposarcoma (DDLS) of the colon, management of which is unclear and difficult to cope with.

PRESENTATION OF CASE

71 year old female patient with complaints of abdominal pain and swelling was referred to our clinic with the diagnosis of intraabdominal mass. 23 cm × 19 cm × 18 cm tumor starting from the neighborhood of left liver lobe and extending toward pelvic floor was detected on computed tomography. At laparotomy, a multilobulated, soft and yellowish mass was arising from transvers colon and invading greater curvature of stomach. En-bloc removal of the tumor including segmental colon and gastric wedge resection was performed. Postoperative histopathological diagnosis was consistent with dedifferentiated liposarcoma.

DISCUSSION

Liposarcomas are rarely encountered in the gastrointestinal tract. Previously, only ten cases of primary liposarcoma of the colon have been reported worldwide and to our knowledge DDLS of transverse colon is the first case reported in the literature. DDLS is a high-grade aggressive tumor carrying the ability to metastasize. Despite complete removal of tumor recurrence is common in DDLS.

CONCLUSION

The constellation of findings in our patient demonstrates that liposarcomas which histologically exhibit dedifferentiation are associated with a poor clinical prognosis and advocating surgery alone is not recommended.     

Adhesion between glass fiber posts and resin cement: evaluation of bond strength after various pre-treatments

Purpose. To evaluate surface roughness and bond strength of glass fiber posts to a resin cement after various surface treatments. Materials and methods. Sixty individually formed glass fiber posts with a diameter of 1.5 mm and a length of 20 mm were used for this study. They were randomly assigned to six groups of pre-treatment (n = 10/group): Group C, untreated (control); Group SB, sandblasted; Group SC, silica coated; Group HF, hydrofluoric acid-etched; Group N, Nd:YAG laser irradiated; Group E, Er:YAG laser irradiated. Surface roughness of the posts was measured before and after pre-treatment. The posts were then bonded to resin cement and tensile bond strengths were determined in a universal testing machine. For statistical analysis, two-way ANOVA and post-hoc comparison tests (α = 0.05) were performed. Results. The highest bond strength value was observed in group HF, followed by group SC. There was a statistically significant difference in bond strength between group C and groups HF, SC and E (p < 0.001, p = 0.002 and p = 0.041, respectively). Posts of group SB and group N showed the highest surface roughness. Conclusions. The findings of the present study reveal that hydrofluoric acid-etching, silica coating and Er:YAG laser irradiation provided a significant increase in bond strength between glass fiber posts and resin cement.     

Enterogastric brake in rats with segmental bowel resection: role of capsaicin-sensitive nerves

1. Unabsorbed nutrients in the distal gut inhibit upper gastrointestinal motility. 2. The aim of the present study was to investigate changes in gastric motility following segmental resections and to evaluate the role of capsaicin-sensitive afferent neurons that may be responsible for these changes. 3. Wistar albino rats of both sexes (200-250 g) were used. Under aseptic conditions and anaesthesia (100 mg/kg ketamine), a baby-feeding tube was placed distal to the resection in either the ileum or caecum for intraluminal perfusion of saline or 20 lipid. In one group of rats, capsaicin was perfused (0.6) for afferent denervation. One group of rats underwent jejunal and ileal resections with end-to-end anastomosis of the remaining segments and were cannulated distal to these anastomosis. Ten days after the surgery, the percentage gastric emptying of a solid meal was calculated. 4. Intra-ileal (18) and intracaecal (34) lipid perfusions delayed gastric emptying compared with groups perfused with saline (54 and 74, respectively; P< 0.001 and P< 0.01). The delay in gastric emptying by ileal perfusion was significantly greater than that following caecal perfusion (P< 0.05). With both resections, gastric emptying was delayed compared with sham groups (P< 0.05-0.01). Local administration of capsaicin abolished the inhibitory effect of lipid on gastric emptying in healthy intact rats and in the jejunal-resection group, whereas a partial reversal was seen in the ileal-resection group. 5. In conclusion, the present data demonstrate that in both healthy intact rat groups and in short bowel groups, capsaicin-sensitive extrinsic neurons participate in brake mechanisms of the distal gut.     

Evaluation of Incidental Thyroid Nodules in Cancer Patients

Objective

Frequency of thyroid cancer in incidental thyroid nodules identified by imaging techniques in cancer patients is higher than that in the normal population. In the retrospective study, we have both investigated the incidence of thyroid cancer in incidentally identified nodules and compared the imaging techniques to determine whether there is any difference between them in detection of malign nodules.