5-HT(2) receptor-mediated phosphoinositide hydrolysis in bovine ciliary epithelium.

The serotonin 2 (5-HT(2)) receptor antagonists, MCI-9042 (Anplag) and ketanserin, have been shown to lower intraocular pressure in rabbits (1) and humans (2). The mechanism of action of these drugs has not been determined, but it is hypothesized that 5-HT(2) receptors, and possibly alpha-adrenergic receptors, (3) may regulate in part aqueous humor production via an intracellular signal transduction pathway in the ciliary body. We therefore examined whether 5-HT(2) receptors were coupled to phosphoinositide hydrolysis in an organ culture system of isolated bovine ciliary epithelium. 5-HT stimulated [(3)H]inositol phosphates ([(3)H]InsPs) accumulation in a dose-dependent manner with a maximum increase approximately twice over the basal level. The mean EC(50) value was 1.1 microM, which was calculated from four dose-response curves. The 5-HT stimulated accumulation of [(3)H]InsPs was inhibited by spiperone (5-HT(2A/1A) and dopamine 2 (D(2)) antagonists), M-1 (a major metabolite of MCI-9042), ketanserin (5-HT(2A) antagonist), SB-206553 (5- HT(2B/2C) antagonist), and mesulergine (5-HT(2C) antagonist and D(2) agonist). It was not inhibited by chlorpromazine, which is a D(2) receptor antagonist. Accordingly, our study demonstrates that 5-HT(2) receptors are coupled to phospholipase C in bovine ciliary epithelium.     

Migration of keratinocytes is impaired on glycated collagen I

Advanced glycation end products are the chemical modification of proteins induced by sugars in a hyperglycemic condition. Extracellular matrix proteins are prominent targets of nonenzymatic glycation because of their slow turnover rates. The aim of this study was to investigate the influence of nonenzymatic glycation of type I collagen on the migration of keratinocytes. The migration of keratinocytes was dramatically promoted on native type I collagen-coated dishes compared with that on uncoated dishes. When type I collagen was glycated with glycolaldehyde, large amounts of advanced glycation end products were produced; the glycated collagen I-coated dishes did not promote the migration of keratinocytes. Glycated collagen I did not affect the proliferative capacity of keratinocytes. However, the adhesion of keratinocytes to glycated collagen I was profoundly diminished in a glycation intensity-dependent manner. alpha2beta1 integrin is responsible for the migration and adhesion of keratinocytes to type I collagen. Pretreatment with glycated collagen I did not affect the expression level or functional activity of alpha2beta1 integrin on keratinocytes. These findings suggest that in the presence of glycated collagen I, keratinocytes lose their adhesive and migratory abilities. As the glycation did not modify the alpha2beta1 integrin on keratinocytes, it is suggested that glycation may diminish the binding capacity of type I collagen.     

Human anticentriole autoantibody in patients with scleroderma and Raynaud's phenomenon

Unique autoantibody was found in sera from two different patients that reacted with centrioles of both cultured mammalian cells and human peripheral leukocytes as detected by the indirect immunofluorescent method. Sera from the same individuals, one with scleroderma and the other suffering from Raynaud's phenomenon, also stained the basal bodies of rat tracheal ciliated cells by the identical technique. Data from subsequent investigations have suggested that the antigen(s) involved in the reaction are water-insoluble protein(s) or polypeptide(s) associated with centrioles and are distinct from microtubular proteins or purine nucleoside phosphorylase.     

Minimally invasive therapy under image guidance--emphasizing MRI-guided cryotherapy

Cryotherapy may provide a method for the focal destruction of cancerous tissue while preserving most of the surrounding normal tissue. The mechanisms of tissue injury in cryotherapy are 1) intracellular ice formation, 2) dehydration of cells, and 3) stagnation of microcirculation. MR images were superior to CT and ultrasound in monitoring interstitial cryotherapy, because the very short T2 relaxation time of ice affords excellent contrast between the ice and surrounding tissue, allowing an accurate depiction of the entire extent of the iceball. MR imaging demonstrates the iceball as sharply marginated regions of signal loss that expanded and engulfed the renal and hepatic masses with clear contrast between the iceball and surrounding tissue. Recently, a fast Joule-Thomson cryocycling device for MR-compatible cryotherapy application was developed and clinical trials under MRI-guided monitoring were performed in several sites of the body. In our series, cryotherapy was performed in 14 cases of renal tumor and 4 cases of hepatic malignancy under the guidance of a horizontal open MR system. Fourteen of the 18 cases were discharged a day after cryotherapy. One of the residual tumors at the margin of a renal cancer required re-cryoablation. All cryoablated tumors resolved and there were no serious complications and no clinically significant changes-during the follow-up study.     

A locus for posterior polymorphous corneal dystrophy (PPCD3) maps to chromosome 10

Posterior polymorphous corneal dystrophy (PPCD) is an autosomal dominant disorder characterized by corneal endothelial abnormalities, which can lead to blindness due to loss of corneal transparency and sometimes glaucoma. We mapped a new locus responsible for PPCD in a family in which we excluded the previously reported PPCD locus on 20q11, and the region containing COL8A2 on chromosome 1. Results of a 317-marker genome scan provided significant evidence of linkage of PPCD to markers on chromosome 10, with single-point LOD scores of 2.63, 1.63, and 3.19 for markers D10S208 (at (circumflex)theta = 0.03), D10S1780 (at (circumflex)theta = 0.00), and D10S578 (at (circumflex)theta = 0.06). A maximum multi-point LOD score of 4.35 was found at marker D10S1780. Affected family members shared a haplotype in an 8.55 cM critical interval that was bounded by markers D10S213 and D10S578. Our finding of another PPCD locus, PPCD3, on chromosome 10 indicates that PPCD is genetically heterogeneous. Guttae, a common corneal finding sometimes observed along with PPCD, were found among both affected and unaffected members of the proband's sib ship, but were absent in the younger generations of the family. Evaluation of phenotypic differences between family members sharing the same affected haplotype raises questions about whether differences in disease severity, including differences in response to surgical interventions, could be due to genetic background or other factors independent of the PPCD3 locus.     

Correlation of urine type I collagen-cross-linked N telopeptide levels with bone scintigraphic results in prostate cancer patients

The diagnostic potential of a new bone resorption marker, type I collagen-cross-linked N telopeptide (NTx), for bone metastasis of prostate cancer was evaluated. Ninty-one prostate cancer patients underwent bone scintigraphy, and urine NTx/creatinine (NTx/Cr) was measured. Urine NTx/Cr levels were compared with bone scintigraphic results. Urine NTx/Cr levels in the bone metastasis-positive group (n = 47) were 92.9 +/- 105.1 nmol/L of bone collagen, which is equivalent to per millimole of urinary creatinine (nmol/L BCE/mmol/L Cr), significantly higher than the level of the bone metastasis-negative group (n = 44) (59.0 +/- 41.6 nmol/L BCE/mmol/L Cr). When patients were classified by the extent of disease grade (EOD grade) nomenclature, the urine NTx/Cr level of the EOD (4+) group was 209.5 +/- 186.5 nmol/L BCE/mmol/L Cr. This level was significantly higher than those of the EOD (-) group (59.0 +/- 41.6 nmol/L BCE/mmol/L Cr), EOD (1+) group (59.0 +/- 47.8 nmol/L BCE/mmol/L Cr), and EOD (2+) group (81.1 +/- 41.3 nmol/L BCE/mmol/L Cr). However, no significant difference was observed between the EOD (-) and EOD (1+) groups. The mean change in urine NTx/Cr level 3 to 17 months after the first bone scintigraphy and urine NTx/Cr examination in the bone metastasis-progression group (n = 8) was 11.0 +/- 31.2 nmol/L BCE/mmol/L Cr, significantly higher than that in the bone metastasis-regression group (n = 15) (-26.8 +/- 40.7 nmol/L BCE/mmol/L Cr). In conclusion, urine NTx /Cr can be measured noninvasively and reflects the state of bone metastasis. However, the sensitivity of urine NTx/Cr is not as high as that of bone scintigraphy. Therefore, it may provide an auxiliary diagnostic index for bone scintigraphy.     

Electrophysiological and pharmacological studies on the mechanisms of ventricular tachycardia

Employing electrophysiological and pharmacological methods, the mechanisms of recurrent ventricular tachycardia were studied in 31 patients, 18 with old myocardial infarction and 13 with idiopathic ventricular tachycardia. In the cases of ventricular tachycardia with old myocardial infraction, the initiation and termination of the tachycardia could be achieved by programmed electrical stimulation in 13 out of 18 patients. Endocardial mapping showed that the earliest excitation site during tachycardia was at the border zone of infarction, where the diastolic fragmented activity was detected. Programmed electrical stimulation sometimes provoked more than two kinds of QRS morphology of tachycardia in the same patient. Class IA antiarrhythmic agents were effective in terminating tachycardia. These data suggest that there are multiple reentrant pathways consisting of partially depressed fast fibers at the border zone of infarction. In the cases with idiopathic ventricular tachycardia, the induction and termination of tachycardia was effected by electrical stimulation in 8 out of 13 patients. For the termination of tachycardia, long overdrive pacing was sometimes necessary. The diastolic fragmented activity could not be detected by endocardial mapping. A class IV drug such as verapamil was more effective for the termination of tachycardia than class I drugs, and there were repetitive short runs of ventricular extrasystole observed until the final termination. These data support the reentrant pathways containing slow with enhanced automaticity as the circuit of idiopathic ventricular tachycardia.     

Vascular relaxing mechanism of denopamine in isolated canine coronary,femoral, mesenteric,and renal arteries

Summary We investigated the mechanism of vascular relaxation produced by denopamine (deno), an oral positive inotropic agent that has selective ₁-adrenergic action. Deno concentration-dependently (0.1 µM–30 µM) relaxed ring segments of canine femoral, mesenteric, and renal arteries which were partially precontracted with 1 µm phenylephrine or norepinephrine, but did not relax those precontracted with 5 µM prostaglandin F₂ or 40 mM K⁺. The relaxation was not significantly inhibited by pretreatment with 10 µM propranolol or metoprolol. Deno produced a parallel rightward shift in concentration-response curves to phenylephrine in femoral and renal arteries. The Schild plot yielded linear regressions of slopes of 1.301 ± 0.106 and 0.823 ± 0.122, respectively, which were not significantly different from unity. The pA₂ values of Deno against phenylephrine in femoral and renal arteries were 5.41 ± 0.03 and 5.76 ± 0.06, respectively.On the other hand, Deno concentration-dependently (10 nM–10 µM) relaxed ring segments of canine coronary arteries which were partially precontracted with 5 µM prostaglandin F₂. The relaxation was significantly inhibited by pretreatment with 10 µM metoprolol.In conclusion, vascular smooth muscle relaxation by Deno was mediated through ₁-adrenergic action in canine coronary arteries and through the blocking effect of -adrenoceptors in canine femoral, mesenteric, and renal arteries.     

An apparently higher molecular weight gamma-chain variant in a new congenital abnormal fibrinogen Tochigi characterized by the replacement of gamma arginine-275 by cysteine

A gamma-chain variant with an apparently higher molecular weight than the normal gamma-chain was detected in a new congenital abnormal fibrinogen with impaired polymerization of the fibrin monomer and with normal release of fibrinopeptides A and B in a 51-year-old male. Purified fibrinogen analyzed on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under the reduced condition in the system of Laemmli contained two protein bands in the gamma-chain region (molecular weight, 50,500 as compared with 50,000 for the normal), both with normal crosslinking ability. The presence of two types of gamma- chains was more clearly detected when reduced and carboxymethylated fibrinogen was analyzed by SDS-PAGE or when reduced fragment D2 was analyzed on SDS-PAGE followed by Western blotting, and identified by positive staining for anti gamma-chain monoclonal antibody. Cyanogen bromide- or lysylendopeptidase-cleavage of purified gamma-chains analyzed on reverse-phase high performance liquid chromatography showed the decrease of one peptide compared with the normal and the appearance of an abnormal peptide peak. Amino acid sequence analysis demonstrated that the gamma arginine-275 of gamma-chain variant was replaced by a cysteine. These data suggest that some regions or conformations containing gamma 275 will affect the polymerization of fibrin monomers. The propositus' two daughters had the same abnormal fibrinogen. This unique inherited abnormal fibrinogen was designated as fibrinogen Tochigi, and the gamma-chain variant as gamma Tochigi.     

Usefulness of invasive and non-invasive electrophysiologic studies in the selection of antiarrhythmic drugs for the patients with paroxysmal supraventricular tachyarrhythmia

A comparison of the effects of several antiarrhythmic agents was made in a study of 70 patients - 15 with manifest Wolff-Parkinson-White (WPW) syndrome, 17 with concealed WPW syndrome, 18 with AV nodal re-entrant tachycardia, 14 with paroxysmal atrial fibrillation and 6 with paroxysmal atrial flutter - employing intracardiac stimulation and esophageal pacing. For the termination of paroxysmal supraventricular tachycardia, intravenous administration of verapamil or aprindine was more effective than that of disopyramide or procainamide. In AV nodal re-entrant tachycardia, verapamil was the most effective for termination. In the manifest WPW syndrome, disopyramide or aprindine was indicated especially for patients with the accessory pathways of the short antegrade refractory period, because these drugs lengthened the refractory period of the accessory pathways. For the purpose of converting atrial fibrillation or flutter to the sinus rhythm, type IA drugs such as disopyramide were indicated. However, verapamil was effective for slowing down the ventricular rate in atrial fibrillation or flutter except in cases of manifest WPW syndrome. A 6-month follow-up study showed that oral administration of verapamil was also useful for putting a stop to the attacks in 24 out of 32 patients with paroxysmal supraventricular tachycardia, while oral disopyramide prevented the recurrence of atrial fibrillation in only 4 of 10 patients.