Posterior pituitary bright spot in large adenomas: MR assessment of its disappearance or relocation along the stalk

PURPOSE: To evaluate the disappearance or relocation patterns of posterior pituitary bright spot (PPBS) in the infundibuloneurohypophyseal (INH) system and endocrinologic implications in large pituitary adenomas. MATERIALS AND METHODS: Sixty-nine patients with adenoma and supradiaphragmatic extension were classified into PPBS-visible and PPBS-nonvisible groups on the basis of findings at preoperative T1-weighted magnetic resonance (MR) imaging. The adenoma shapes were classified into hourglass type with indentation and barrel type without indentation at the diaphragmatic level. RESULTS: The PPBS-visible group included 55 (80%) patients. PPBS most commonly occurred at the distal pituitary stalk immediately above the diaphragm in 48 patients with hourglass-type adenoma. In the remaining seven patients with barrel-type adenoma, PPBS occurred in the sella or in varying sites along the pituitary stalk. Postoperatively, two patients, whose PPBS became nonvisible, developed persistent diabetes insipidus. The PPBS-nonvisible group included 14 (20%) patients. Five had hourglass-type and nine had barrel-type adenoma. Occurrence of the barrel type was marked. In these patients, four developed postoperative permanent diabetes insipidus. CONCLUSION: The diaphragm, a probable major anatomic determinant of indentation, may serve as a transportation blockade and facilitate proximal accumulation of PPBS material, as evidenced in the hourglass-type adenoma. PPBS was more commonly nonnvisible in the barrel-type adenoma. The presence of PPBS in the INH system indicates its functional maintenance in large adenomas.     

Pathological evaluation of orbital tumours in Japan: analysis of a large case series and 1379 cases reported in the Japanese literature

PURPOSE: To review epidemiological features of orbital tumours in Japan. METHODS: Retrospective, observational case series and systematic review. A total of 104 patients with orbital tumours collected at the authors' institution during 1983-2002 were assessed. In addition, 1379 cases from a large series of orbital tumours diagnosed by histopathological analysis that were previously published in Japanese ophthalmological journals from 1980 to 2004 were analysed. RESULTS: After combining the current data with the previously published cases, there were a total of 1483 lesions with 47% classified as primary, 30% as secondary and 22% as inflammatory. The most common primary tumour was malignant lymphoma (12%) followed by pleomorphic adenoma (7%). Carcinomas from the lung, breast and thyroid were found to predominate among orbital metastases. Inflammatory pseudotumour had the highest lesion frequency (18%). CONCLUSIONS: Malignant lymphoma by far was found to have the most dramatic increases within the recent reported series. Pleomorphic adenomas in Japan were found to be much more common compared with that reported for American and European studies.     

Advanced methods for the manipulation of herpesvirus genomes

The Herpesviridae are a family of viruses which have a large genome of linear, double-stranded DNA (> 120 kb). It has been quite difficult to clone and modify herpesvirus genomes because of their large sizes. Recently, several groups of investigators demonstrated successful cloning of infectious herpesvirus genomes as bacterial artificial chromosomes (BACs). In this review, I describe the recent development of methods to modify the cloned viral genomes. The methods are: (i) homologous recombination in E. coli which allows targeted mutagenesis of any specific viral sequence, and (ii) mutagenesis which allows random modification of entire viral genomes. Both methods should facilitate both the study of herpes viruses and the development of herpesvirus-based vector system.     

Basic physiological studies of the effects of autonomic drugs on the pacemaker of renal pelvic peristalsis

An electromyographic study of the effects of noradrenaline, isoproterenol, and acetylcholine on the calyceopelviureteral system was performed in isolated canine pyeloureteral preparations with continuous infusion of oxygenated Krebs-Ringer solution into the renal pelvis to provide a condition of constant urine volume. The calyceal pacemaker was slightly stimulated by noradrenaline and acetylcholine and was also quickened in pace by isoproterenol. Noradrenaline caused a marked elevation of renal pelvic pressure and enhancement of propagation of peristalsis generated at the pacemaker region with an increase in frequency of ureteral peristalsis. In contrast, isoproterenol lowered the renal pelvic pressure to an extent of pressure wave disappearance and concomitant blockade of peristaltic movement propagation to the ureter, with consequent suppression of ureteral peristalsis. Acetylcholine slightly reduced the renal pelvic pressure but at the same time exerted a marked effect on the ureter, causing a transient increase in frequency of ureteral peristalsis.     

One and a half syndrome and MRI--a case report and functional neuroanatomy of the syndrome

This is a case report of 63 year old men who presented one and a half syndrome with ipsilateral peripheral type facial palsy due to lacunar infarct. MRI taken one week after the onset (TR 2000, TE 38) demonstrated small high intensity lesion, 4 mm in diameter, located at the dorsal portion of pontine tegmentum, contacting with the floor of 4th ventricle. This MRI coincides with the lesion limited to the abducens nucleus and genu of facial nerve. Traditionally, projections from the PPRF to the ipsilateral abducens nucleus and opposite MLF was postulated. Recently, however, experiment on monkey and autopsy cases showed projection from abducens nucleus, instead of PPRF, to the opposite MLF has been proposed. MRI findings in this case support the latter hypothesis. It is expected that, with the advent of MRI, more meticulous functional neuroanatomy will be developed.     

Single local injection of recombinant fibroblast growth factor-2 stimulates healing of segmental bone defects in rabbits

The effects of a single local injection of recombinant human fibroblast growth factor-2 on the healing of segmental bone defects were evaluated in rabbits. One month after the external fixator originally designed for this experiment was installed in the tibia of the rabbit, a 3-mm bone defect was created by an osteotomy in the middle of the tibia and 0, 50, 100, 200, or 400 μg of fibroblast growth factor-2 in 100 μg of saline solution was injected into the defect. Injection of the growth factor increased the volume and mineral content of newly made bone at the defect in a dose-dependent manner with significant effects at Concentrations of 100 μg or greater. These significant effects were observed at 5 weeks and later. One hundred micro-grams of the growth factor increased the volume and mineral content of newly made bone by 95 and 36%, respectively, at 5 weeks. These results indicate that a single local injection of fibroblast growth factor-2 stimulates the healing of segmental defects. We speculate that such an injection could be clinically useful for the healing of fractures even when the fracture gap is rather large.     

Response of the renal pacemaker to beta 1-adrenoceptor agonist: difference from the cardiac pacemaker

Electromyographic responses of the canine-pyeloureter to dobutamine, a beta 1-adrenoceptor agonist were investigated in vitro. Dobutamine produced a marked enhancement of potential in the pelvicalyceal (PC-) border, but failed to evoke noticeable responses in the renal pelvis and ureter. Dobutamine, however, made the pacemaker rhythm a little slow. This finding shows that the renal pacemaker is somewhat different form the cardiac pacemaker, pace of which is quickened by dobutamine.     

Mechanical properties of glycerinated guinea-pig temporal and masseter muscles

At a muscle length, L0 (just taut), isometric tension and tension transients in response to rapid step stretches in length (less than 1 per cent of L0 within 2 ms) were measured at constant levels of Ca2+ activation of various magnitudes in glycerinated temporal and masseter muscles (1.7-2.5 mm long, 48-96 micron in diameter) from guinea pigs. The experiments were at 20 and 30 degrees C, and pH 6.8. Steady isometric tension increased in a sigmoid fashion as Ca2+ varied from about pCa 6.6 to 4.4 in both muscles. However, the maximum tension of temporal muscle was about 4.4 times greater than that of masseter muscle at 20 degrees C. The tension transients showed an immediate tension increase coincident with the stretch (the first phase) and an exponential-like tension decrease (the second phase). The time constant of the second phase was about 87.5 ms in temporalis and 3.7 ms in masseter at 30 degrees C. Decreasing temperature from 30 to 20 degrees C markedly increased the time constant of the tension response in the second phase (Q10 of about 3.4 in temporalis and 2.2 in masseter). Although there was a difference in the sarcomere length between the two muscles at L0 (2.14 micron in temporalis and 1.84 micron in masseter), the mechanical characteristics were almost independent of the muscle length. Thus the cross-bridges in temporalis appear to cycle more slowly and produce more isometric tension than those in masseter muscle.