Functional role of the C-terminal domain of smooth muscle myosin light chain kinase on the phosphorylation of smooth muscle myosin

Smooth muscle myosin light chain kinase (MLCK) is known to bind to thin filaments and myosin filaments. Telokin, an independently expressed protein with an identical amino acid sequence to that of the C-terminal domain of MLCK, has been shown to bind to unphosphorylated smooth muscle myosin. Thus, the functional significance of the C-terminal domain and the molecular morphology of MLCK were examined in detail. The C-terminal domain was removed from MLCK by alpha-chymotryptic digestion, and the activity of the digested MLCK was measured using myosin or the isolated 20-kDa light chain (LC20) as a substrate. The results showed that the digestion increased K(m) for myosin 3-fold whereas it did not change the value for LC20. In addition, telokin inhibited the phosphorylation of myosin by MLCK by increasing K(m) but only slightly increased K(m) for LC20. Electron microscopy indicated that MLCK was an elongated molecule but was flexible so as to form folded conformations. MLCK was crosslinked to unphosphorylated heavy meromyosin with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide in the absence of Ca(2+)/calmodulin (CaM), and electron microscopic observation of the products revealed that the MLCK molecule bound to the head-tail junction of heavy meromyosin. These results suggest that MLCK binds to the head-tail junction of unphosphorylated myosin through its C-terminal domain, where LC20 can be promptly phosphorylated through its catalytic domain following the Ca(2+)/CaM-dependent activation.

Enhancement of submicroscopic damage of the nasal epithelium by topical allergen challenge in patients with perennial nasal allergy

The purposes of this study were to clarify whether damage of the nasal epithelium exists in patients with nasal allergy, and how the morphology of the epithelium changes after topical allergen challenge. Electron microscopy revealed 2 characteristic features in the nasal epithelium of patients with perennial nasal allergy--an increase in the number of epithelial cells with cytoplasmic vacuoles, and markedly widened intercellular spaces--although these changes were unclear under light microscopy. The density of vacuolated cells significantly increased 24 hours after allergen challenge. Further, the number of eosinophils that were associated with vacuolated cells was significantly higher in patients with nasal allergy than in controls. These morphological changes, thus, were considered to be types of damage to the nasal epithelium associated with nasal allergy. Such changes may be among the causes of nasal hyperreactivity, which is an important feature of nasal allergy.

Amino acid residues in ribonuclease MC1 from bitter gourd seeds which are essential for uridine specificity

The ribonuclease MC1 (RNase MC1), isolated from seeds of bitter gourd (Momordica charantia), consists of 190 amino acids and is characterized by specific cleavage at the 5'-side of uridine. Site-directed mutagenesis was used to evaluate the contribution of four amino acids, Asn71, Val72, Leu73, and Arg74, at the alpha4-alpha5 loop between alpha4 and alpha5 helices for recognition of uracil base by RNase MC1. Four mutants, N71T, V72L, L73A, and R74S, in which Asn71, Val72, Leu73, and Arg74 in RNase MC1 were substituted for the corresponding amino acids, Thr, Leu, Ala, and Ser, respectively, in a guanylic acid preferential RNase NW from Nicotiana glutinosa, were prepared and characterized with respect to enzymatic activity. Kinetic analysis with a dinucleoside monophosphate, CpU, showed that the mutant N71T exhibited 7.0-fold increased K(m) and 2.3-fold decreased k(cat), while the mutant L73A had 14.4-fold increased K(m), although it did retain the k(cat) value comparable to that of the wild-type. In contrast, replacements of Val72 and Arg74 by the corresponding amino acids Leu and Ser, respectively, had little effect on the enzymatic activity. This observation is consistent with findings in the crystal structure analysis that Asn71 and Leu73 are responsible for a uridine specificity for RNase MC1. The role of Asn71 in enzymatic reaction of RNase MC1 was further investigated by substituting amino acids Ala, Ser, Gln, and Asp. Our observations suggest that Asn71 has at least two roles: one is base recognition by hydrogen bonding, and the other is to stabilize the conformation of the alpha4-alpha5 loop by hydrogen bonding to the peptide backbone, events which possibly result in an appropriate orientation of the alpha-helix (alpha5) containing active site residues. Mutants N71T and N71S showed a remarkable shift from uracil to guanine specificity, as evaluated by cleavage of CpG, although they did exhibit uridine specificity against yeast RNA and homopolynucleotides.

Clinical surveillance of a thin bipolar pacing lead

A total number of 415 co-radial, bipolar pacing leads (189 atrial leads; 226 ventricular leads) were implanted in 228 patients between November 1994 and July 1999. Mean pacing thresholds at the implantation were normal at 0.6 V in the atrium and at 0.4 V in the ventricle with a pulse duration of 0.4-0.5 ms. Lead impedance was relatively low (337-447 ohms for atrial leads; 369-459 ohms for ventricular leads) at the implantation and during the follow-up periods. No definite failure in lead materials was observed in either atrial or ventricular leads (mean follow-up of 19.7 and 19.2 months, respectively: up to 52.9 months for both leads). Predicted clinical surveillance up to 10 years calculated statistically showed that the upper 95% confidence limit was a constant of 100%. The lower 95% confidence limits at 5, 7, and 10 years were estimated to be 98.0%, 97.2%, and 96.0%, respectively. From the present study, the ThinLine lead is reliable for both sensing and pacing thresholds, and has excellent predicted lead longevity. Nevertheless, further observation is required regarding cost performance, such as early replacement of the pacemaker generator, because of the lower pacing lead impedance.

Time course of changes in absorption of macromolecule through the nasal mucosa after antigen challenge in guinea pig model of allergic rhinitis

The time course of changes in absorption of horseradish peroxidase (HRP) through the nasal mucosa after antigen challenge was evaluated in a guinea pig model of allergic rhinitis immunized with ovalbumin. Before and at 5 minutes, 4 hours, and 24 hours after nasal antigen challenge, both nasal cavities were filled with 5% HRP solution for 30 minutes, and blood was obtained to measure serum HRP levels by enzyme-linked immunosorbent assay. In immunized animals, the serum HRP levels were 2.3 times higher than those of normal controls (p<.05) before antigen challenge, which was performed 7 days after a series of nasal antigenic sensitizations. At 5 to 35 minutes after antigen challenge, the HRP levels decreased to one sixth of the prechallenge levels (p<.05), and they did not show a difference from the control levels. However, they increased markedly at 4 and 24 hours after antigen challenge (p<.01). The present study suggests that the absorption of macromolecules through the allergic nasal mucosa is enhanced markedly, depending upon the time course after antigen challenge, although it shows no apparent difference from normal controls during the dominant exudative process.

Evaluation of the validity of the 1997 International Union Against Cancer TNM classification of major salivary gland carcinoma

BACKGROUND

The TNM classification (International Union Against Cancer) of salivary gland carcinoma was revised in 1997. In this study, the authors have evaluated the validity of this new TNM classification and clinical staging in 1683 patients with parotid gland carcinoma.

METHODS

Reclassification was conducted according to the new classification based on the clinical data of 1683 patients registered to the salivary gland division of the Japanese Joint Committee on TNM classification. The 5- and 10-year survival rates according to TNM classification were calculated for 1074 patients whose prognosis could be followed up. Finally, the distribution of the total patient population was analyzed using the new staging and the survival curves for each disease stage.

RESULTS

The variance of the patients for T1 to T4 was appropriate using the new T classification. The 5- and 10-year survival rates corresponded well to the degree of progression of TNM. However, there were only nine patients with Stage III, and marked nonuniformity in the staging was observed. The separation of the survival curves for each stage was not clear, and no significant differences between the survival curves of Stages II and III and Stages III and IV were observed. When the authors classified T1N1M0, T2N1M0, T3N1N0, and T4N0M0, which have 5- and 10-year survival rates similar to Stage III, distribution of patients and separation of the survival curves in each stage improved markedly.

CONCLUSIONS

The results of the current study confirm that the new TNM classification system is valid. However, a significant problem was observed with respect to the new clinical staging. The authors propose that T1N1M0, T2N1M0, T3N1M0, and T4N0M0 be classified as Stage III.

Effect of a single oral dose of pilsicainide on pacing thresholds in pacemaker patients with and without paroxysmal atrial fibrillation

A single oral dose of pilsicainide, a class 1c antiarrhythmic drug, is effective in terminating acute-onset atrial fibrillation (AF), but its effect on pacing thresholds in pacemaker patients is unknown. The present study measured atrial and ventricular pacing thresholds after a single oral dose of pilsicainide in patients with and without AF. Twelve patients with dual-chamber pacemakers were evaluated. Pacing thresholds as well as plasma pilsicainide concentration were measured prior to and then at 30, 60, 90, 120 and 180 min and 24h following a single oral dose of pilsicainide (150 mg). Six patients had paroxysmal AF and the remaining 6 did not. Pacing thresholds increased significantly (134+/-8%) in the atrium (p<0.05) and in the ventricle (155+/-11%; p<0.001) following pilsicainide administration in all 12 patients. Plasma concentrations of pilsicainide showed a positive liner correlation with pacing thresholds (R=0.62, p<0.0001 in the atrium; R=0.74, p<0.0001 in the ventricle). Atrial pacing thresholds in the patients with AF showed a significant increase at 90, 120 and 180 min compared with the patients without AF (p<0.05). There was no significant difference in either the ventricular pacing threshold or the plasma pilsicainide concentration in the patients with and without AF. It was concluded that a single oral dose of pilsicainide increases the pacing thresholds in both the atrium and ventricle in a selected group of pacemaker-implanted patients; that is, those who are aged and with AF. Thus, careful attention should be paid to pacemaker-dependent patients, particularly those with paroxysmal AF, when administering pilsicainide.

Ventricular pacing failure after a single oral dose of pilsicainide in a patient with a permanent pacemaker and paroxysmal atrial fibrillation

A single oral dose of pilsicainide, a Class Ic antiarrhythmic drug, is a widely used and highly effective therapy for termination of recent onset atrial fibrillation. We report on a patient in which ventricular pacing failure occurred immediately after a single oral dose of pilsicainide. It did not exhibit a parallel relationship between the change in the pacing threshold and plasma concentration of pilsicainide, and the recovery period for the ventricular pacing threshold was longer than that of the plasma concentration of pilsicainide in this patient. Careful attention should be paid when a single oral dose of pilsicainide for termination of recent onset atrial fibrillation is used in patients with permanent pacemakers.

Evaluation of outcome and QOL in patients with craniofacial resection for malignant tumors involving the anterior skull base

The purpose of this study was to retrospectively evaluate the effectiveness of anterior craniofacial resection in the treatment of nasal and paranasal malignant tumors involving anterior skull base. Between 1992 and 1998, 13 patients with nasal or paranasal malignant tumors underwent this surgical procedure. The site and time of metastasis or recurrence, and survival outcome were retrospectively surveyed. Current status of long-surviving patients and their subjective assessment of the surgical treatment were also evaluated through questionnaires. Median follow-up period was 52 months. Nine patients (69%) were alive with no evidence of disease. Of these patients, eight had survived for more than three years. Recurrence or metastasis occurred in four patients (31%). The mean time interval between surgery and recurrence or metastasis was 11 months. According to the results of questionnaires to long-surviving patients, 89% patients had some complaints. In particular, complaints of unsightly appearance were manifested by all these patients. When the patients themselves evaluated their current conditions resulting from this surgical treatment, 63% were dissatisfied. These results suggest that this surgical treatment is valid for selected patients in regard to survival outcome. When the effectiveness of this treatment is evaluated, however, psychological and functional issues should not be taken lightly.

Crystal structures of the ribonuclease MC1 from bitter gourd seeds, complexed with 2'-UMP or 3'-UMP, reveal structural basis for uridine specificity

Ribonuclease MC1 (RNase MC1) isolated from seeds of bitter gourd (Momordica charantia) consists of 190 amino acids and is characterized by a preferential cleavage at the 5'-side of uridine. This uridine specificity distinguishes RNase MC1 from other enzymes belonging to the RNase T2 family. The three-dimensional structures of RNase MC1, in a complex with either 2'-UMP or 3'-UMP, were determined at 1.48 and 1.77 A resolutions, respectively. The side chains of Gln9 and Asn71 interact with O4 and N3, respectively, of the uracil base by hydrogen bondings. In addition, the uracil base is sandwiched by the hydrophobic side chains of Leu73 and Phe80. Compared with these amino acid residues and corresponding residues in RNases in the RNase T2 family, Gln9 and Phe80 are highly conserved in the RNases in T2 family, while Asn71 and Leu73 in RNase MC1 are variant in sequences. It is thus likely that interactions of the side chains of Asn71 and Leu73 with the uracil base are responsible for the absolute uridine specificity of RNase MC1. Site-directed mutagenesis experiments showed that replacement of Asn by Thr decreased both the catalytic efficiency and the binding affinity by 2.3- and 7.0-fold, respectively, and substitution of Leu73 for Ala predominantly decreased the binding affinity by 14. 5-fold, compared with findings in case of wild-type RNase MC1. It is thus demonstrated that Asn71 and Leu73 play an essential role in uridine preference for RNase MC1.

Transepithelial migration of activated eosinophils induces a decrease of E-cadherin expression in cultured human nasal epithelial cells

BACKGROUND

The damage of respiratory epithelium in allergic diseases has a close correlation with the extent of eosinophil infiltration. It seems to be a good possibility that eosinophil infiltration could induce the changes in the expression of the epithelial cell adhesion molecules, which play a key role in the maintenance of structural and functional rigidity of epithelium.

OBJECTIVE

We observed the expression of E-cadherin in cultured human nasal epithelial cells (HNECs) to study whether could it be affected by transepithelial migration of inflammatory cells, especially eosinophils.

METHODS

In vitro study of the transmigration assay was designed using various types of inflammatory cells and HNEC monolayers. Various assays of each experimental group were done under the stimulation of interleukin-5 (IL-5) and/or platelet activating factor (PAF). Subsequently immunohistochemistry for E-cadherin was performed in the HNECs. The intensity of immunofluorescence of E-cadherin was quantified using confocal laser scanning microscopy (CLSM) system and compared before and after the transmigration.

RESULTS

The mean intensity of immunofluorescence for E-cadherin decreased significantly after the transmigration of any types of inflammatory cells. Above all, the migration of eosinophils treated with IL-5 and PAF had an eminent effect on the decrease, whereas the degranulation extracts derived from eosinophils activated by IL-5 and secretory IgA (sIgA) did not affect the intensity.

CONCLUSION

This work suggests that transepithelial migration of inflammatory cells can directly induce the decrease in epithelial E-cadherin expression. Furthermore, the most prominent change was induced by transmigration of activated eosinophils, which might be caused by some mechanisms independent of the eosinophil contents. The decrease in E-cadherin expression may trigger the damage of epithelial barrier, which contributes to the pathogenesis of allergic diseases.

Successful treatment of malignant neurocardiogenic syncope with repeated tilt training program

Recent reports have shown that repeated tilt-table testing or tilt training is a very effective therapy for the treatment of neurocardiogenic syncope induced by head-up tilt testing. The present patient experienced repeated syncopal or presyncopal attacks and had shown prolonged asystole on an electrocardiogram during syncope. The presyncope could be reproducibly induced by head-up tilt testing. Oral propranolol and/or disopyramide therapies failed to prevent his symptoms. Tilt training (2 sessions/day) was repeated every day for 4 weeks at home, and then head-up tilt testing was performed again. The syncope or presyncope was not induced by head-up tilt testing. The patient has continued with this training and has had no symptoms during the follow-up period of 1 year.

Expression and mutational analysis of amino acid residues involved in catalytic activity in a ribonuclease MC1 from the seeds of bitter gourd

The ribonuclease MC1 (RNase MC1) from seeds of bitter gourd (Momordica charantia) consists of 190 amino acids and belongs to the RNase T2 family, including fungal RNases typified by RNase Rh from Rhizopus niveus. We expressed RNase MC1 in Escherichia coli cells and made use of site-directed mutagenesis to identify essential amino acid residues for catalytic activity. Mutations of His34 and His88 to Ala completely abolished the enzymatic activity, and considerable decreases in the enzymatic activity were observed in cases of mutations of His83, Glu84, and Lys87, when yeast RNA was used as a substrate. Kinetic parameters for the enzymatic activity of the mutants of His83, Glu84, and Lys87 were analyzed using a dinucleoside monophosphate CpU. Km values for the mutants were approximately like that for wild-type, while k(cat) values were decreased by about 6 to 25-fold. These results suggest that His34, His83, Glu84, Lys87, and His88 in RNase MC1 may be involved in the catalytic function. These observation suggests that RNase MC1 from a plant catalyzes RNA degradation in a similar manner to that of fungal RNases.

Interleukin-13 and tumour necrosis factor-alpha synergistically induce eotaxin production in human nasal fibroblasts

BACKGROUND

There is increasing evidence that eotaxin is a key mediator in the development of tissue eosinophilia. However, the mechanism involved in the production of eotaxin has yet to be clarified. Most recently, it has been shown that interleukin (IL) -4 induces eotaxin in dermal fibroblasts. A novel cytokine termed IL-13, which binds to the alpha-chain of the IL-4 receptor, shares many biological activities with IL-4. It is known that fibroblasts express the IL-4 receptor and produce collagen type I upon stimulation with IL-4.

OBJECTIVE

We investigated whether IL-13, as well as IL-4, are able to induce eotaxin production in human nasal mucosal fibroblasts (HNMFs). Furthermore, we investigated the effect of costimulation of IL-13 and TNFalpha on eotaxin production.

METHODS

HNMFs, isolated from inferior nasal mucosa samples, were stimulated by various kind of cytokines for 1-36 h at 37 degrees C in 5% CO2. The change in the expression of eotaxin mRNA was then evaluated by reverse transcriptase-polymerase chain reaction and the Southern blot analysis. The amount of eotaxin in the culture media was measured by ELISA.

RESULTS

IL-13 as well as IL-4 dose-dependently induced eotaxin expression in HNMFs. Furthermore, IL-13 and TNFalpha synergistically induced eotaxin expression in HNMFs, while they hardly induced eotaxin expression in endothelial cells, epithelial cells or eosinophils. The synergy was observed when pre-incubation of HNMFs with IL-13 was followed by a stimulation with TNFalpha, or HNMFs were simultaneously stimulated with IL-13 and TNFalpha.

CONCLUSION

These results strongly indicate that IL-13, as well as IL-4, may be important in eotaxin-mediated eosinophilic inflammation in nasal mucosa. In addition, in nasal mucosa, fibroblasts are the major cell source for eotaxin.

Role of vascular reflex in nasal mucosal swelling in nasal allergy

OBJECTIVE

In patients with nasal allergy, antigen challenge on the unilateral nasal mucosa results in nasal secretion not only in the ipsilateral but also in the contralateral nasal cavities that can be inhibited almost completely by premedication with atropine sulfate. The present study was performed to elucidate if centrally mediated vascular reflex induced by antigen challenge plays a role in nasal mucosal swelling in subjects with nasal allergy.

METHODS

Variations of mucosal swelling and mucosal blood flow in the ipsilateral and the contralateral nasal cavities after unilateral antigen challenge were evaluated by acoustic rhinometry and laser Doppler flowmetry in 20 patients with perennial nasal allergy.

RESULTS

Unilateral antigen challenge caused ipsilateral and contralateral nasal mucosal swelling in 17 and 13 patients, respectively. Incidence of contralateral nasal mucosal swelling after unilateral antigen challenge was significantly higher compared with that after control disc challenge (P < .001). In 10 patients in whom unilateral antigen challenge caused bilateral nasal mucosal swelling, significant swelling of the nasal mucosa lasted for more than 30 minutes in the ipsilateral nasal cavity after antigen challenge compared with only 15 minutes in the contralateral nasal cavity. Peak values of contralateral mucosal swelling were 45.3% of those of ipsilateral nasal mucosa.

CONCLUSIONS

Centrally mediated vascular reflex is partially involved in the onset of nasal mucosal swelling observed after antigen challenge in subjects with nasal allergy. However, nasal mucosal swelling that persists and proceeds even 20 minutes after antigen challenge is caused by the direct effects of chemical mediators on the nasal vasculature.

Successful treatment of severe orthostatic hypotension with cardiac tachypacing in dual chamber pacemakers

Orthostatic hypotension is an evolving and disabling disease usually observed in elderly patients with dramatic consequences on morbidity, mortality, and impairing the quality of life. We studied the effects of the pacing rate and AV interval on the blood pressure drop in the upright position in two patients with previously implanted pacemakers for sinus node dysfunction. Although the AV interval did not affect the blood pressure drop in the upright position, tachypacing at 100 paces/min improved it dramatically and prevented syncope. Cardiac tachypacing is a useful therapeutic option in severe refractory orthostatic hypotensive patients, especially those with chronotropic incompetence.

Livedo vasculitis associated with regional cytophagic histiocytoses

We report a 70-year-old woman who developed recurrent multiple ulcers and residual atrophic scars on her legs and feet. The histology showed fibrinoid material in the dermal vessel walls causing partial to complete occlusion of the lumina. Capillary tufting and dilatation were also noted in the dermis. There was no vasculitis or panniculitis. Extravasated red blood cells were seen throughout the dermis; these were engulfed by benign-appearing histiocytes around the dermal-fat junction. As she was generally well and there was no evidence of the presence of cytophagic cells in her extracutaneous organs, she was diagnosed with regional phagocytic histiocytoses supposedly triggered by extravasated red blood cells.

[Procainamide-induced skin eruption associated with disseminated intravascular coagulation in a patient with sustained ventricular tachycardia]

A 70-year-old man, who had sustained ventricular tachycardias following a previous anterior myocardial infarction, suffered from skin eruptions and abnormal blood tests after 10 days following the oral administration of 1500 mg/day of procainamide. These abnormalities disappeared early after the discontinuation of oral procainamide. However, similar skin eruptions exhibited again when the procainamide was resumed. These results suggest that oral procainamide therapy induces skin eruptions and serious abnormal blood tests in the patient. No reports have suggested such a serious early complication by procainamide therapy. Careful follow-up is needed after the administration of oral procainamide therapy.

Pathophysiological features of the nasal mucosa in patients with idiopathic rhinitis compared to allergic rhinitis

BACKGROUND

The literature on abnormality of vasomotor responses of the nasal mucosa to cold stimulation of the skin in idiopathic rhinitis is conflicting. The objective of this study was to elucidate pathophysiological features of the nasal mucosa in idiopathic rhinitis compared to allergic rhinitis.

METHODS

The following were studied in patients with idiopathic rhinitis and allergic rhinitis and in normal controls: (1) threshold of the nasal reaction to histamine; (2) inflammatory cells in nasal lavage and scraped nasal mucosal epithelium, and (3) nasal vasomotor response to cold stimulation of the feet evaluated by acoustic rhinometry.

RESULTS

Inflammatory cells were not found to be involved in idiopathic rhinitis. Nasal reactivity to histamine was significantly enhanced in patients with idiopathic rhinitis compared to normal controls, but was significantly lower compared to those with allergic rhinitis. The most prominent finding in idiopathic rhinitis was nasal mucosal swelling induced by cold stimulation of the feet. While in normal controls, cold stimulation of the feet caused mucosal contraction due to sympathetic excitation, sympathetic nasal vasomotor response in idiopathic rhinitis patients was significantly inhibited and caused mucosal swelling and enhanced nasal secretion. Mucosal reactions observed in allergic rhinitis were between those observed in idiopathic rhinitis and in normal controls. Cold stimulation of the feet increased systolic blood pressure by 5-15 mm Hg, but the degree of increase observed in the 3 groups was almost equal.

CONCLUSIONS

The above findings indicate that patients with idiopathic rhinitis have abnormalities that inhibit sympathetic reactions and enhance parasympathetic vasomotor response at peripheral levels, possibly in the nasal mucosa.

Bone window CT evaluation of the nasal cavity for the transsphenoidal approach

Bone window CT findings sliced parallel to the transsphenoidal surgical route were evaluated preoperatively in 104 patients with pituitary lesions in order to assess their clinical significance. (1) The width and depth of the transsphenoidal operative fields were measured. The piriform aperture was 26.3 mm (SD 2.5) in maximum width, the origin of inferior nasal concha 27.0 mm (SD 2.5) and the origin of the middle nasal concha 26.8 mm (SD 3.8), respectively. The distance between the piriform aperture and the sellar floor was 61.6 mm (SD 3.6). The operative field was cylindrical in shape, approximating 26-27 mm in width and 62 mm in depth. (2) The width and length of bony nasal cavity were different by 2-3 mm in patients with and without acromegaly. (3) In re-operated patients, the location of thinned or atrophic nasal mucosa, residual bony septum and narrow sellar floor opening, which needed further bony removal were demonstrated. Bone window CT provides direct visualization of the nasal anatomy for the approach, and is useful in screening for patients with a narrow nasal cavity. It helps to determine rhinological manoeuvres for providing wide operative fields at the nasal cavity and sellar floor.

Possible involvement of hypothyroidism as a cause of lithium-induced sinus node dysfunction

Although several reports have stated that even therapeutic levels of lithium can induce sinus node dysfunction, the mechanism has not been fully elucidated. We present here two patients with sinus node dysfunction after long-term lithium therapy. Following lithium discontinuation, sinus node function recovered completely. After resuming lithium, however, irreversible sinus node dysfunction recurred and a permanent pacemaker was implanted in one patient. The serum concentration of lithium was within therapeutic levels. Nevertheless, hypothyroidism was associated with the sinus node dysfunction in both patients. Thus, thyroid function may play an important role in sinus node dysfunction induced by lithium.

Comparative role of peptide leukotrienes and histamine in the development of nasal mucosal swelling in nasal allergy

To evaluate the importance of histamine and peptide leukotrienes (LTs) in the development of nasal mucosal swelling in nasal allergy, H1 receptor antagonist (mequitazine, 6 mg, in 2 divided doses, Rhône-Poulenc Rorer, France) and LT receptor antagonist (ONO-1078, pranlukast, 450 mg, in 2 divided doses, Ono Pharmaceutical Co, Ltd, Osaka) were administered orally for 7 days to 16 subjects with perennial nasal allergy to house dust mites, and the effects of receptor blockers of these chemical mediators on the effective cross-sectional area of the nasal cavity (ECA) at rest, at exercise load, at antigen challenge, and at exercise load following antigen challenge were studied. After the administration of H1 receptor antagonist, ECAs at all measurement points slightly increased, but no statistical significance was observed. On the other hand, LT receptor antagonist inhibited ECAs 10 minutes after exercise load, just after the end of antigen challenge, 10 minutes later, and at exercise load following antigen challenge with statistical significance. These results suggest that LTs are involved markedly, and histamine slightly, in the development of nasal mucosal swelling in nasal allergy.

A case in which stent insertion is considered to have triggered contrast medium-induced coronary vasospasm

A Gianturco-Roubin II (GR-II) stent was inserted in a 75-year-old man who developed restenosis of the right coronary artery (RCA) after percutaneous transluminal coronary angioplasty (PTCA). Although the vessel became partially occluded after 7 months, it was redilated by PTCA. Follow-up angiography of the RCA and left coronary artery (LCA) was performed 3 months later. Chest pain with bradycardia and hypotension occurred immediately after this examination, and ST elevation appeared in ECG leads II, III, and aVF. Repeat angiography of the RCA confirmed complete occlusion due to a spasm at a site proximal to the GR-II stent. The spasm was resolved by intracoronary infusion of isosorbide dinitrate (ISDN), and PTCA was carried out for extensive recurrent restenosis of the RCA; however, vascular dissection developed at the distal end of the GR-II stent. Therefore, a Palmaz-Schatz (P-S) stent was placed such that its proximal end overlapped the distal end of the GR-II stent. Follow-up angiography 3 months later showed no restenosis, but an episode of vasospasm similar to the previous one occurred immediately after left ventriculography. The RCA was completely occluded proximal to the GR-II stent because of spasm. Although this spasm was gradually relieved by intracoronary infusion of ISDN, marked spasm was also observed distal to the P-S stent; complete relief was achieved by infusion of additional ISDN.