Whole body nitric oxide synthesis in healthy men determined from [15N] arginine-to-[15N]citrulline labeling

The rates of whole body nitric oxide (NO) synthesis, plasma arginine flux, and de novo arginine synthesis and their relationships to urea production, were examined in a total of seven healthy adults receiving an L-amino acid diet for 6 days. NO synthesis was estimated by the rate of conversion of the [15N] guanidino nitrogen of arginine to plasma [15N] ureido citrulline and compared with that based on urinary nitrite (NO2-)/nitrate (NO3-) excretion. Six subjects received on dietary day 7, a 24-hr (12-hr fed/12-hr fasted) primed, constant, intravenous infusion of L-[guanidino-15N2]arginine and [13C]urea. A similar investigation was repeated with three of these subjects, plus an additional subject, in which they received L-[ureido-13C]citrulline, to determine plasma citrulline fluxes. The estimated rates (mean +/- SD) of NO synthesis over a period of 24 hr averaged 0.96 +/- 0.1 mumol .kg-1.hr-1 and 0.95 +/- 0.1 mumol.kg-1.hr-1, for the [15N]citrulline and the nitrite/nitrate methods, respectively. About 15% of the plasma arginine turnover was associated with urea formation and 1.2% with NO formation. De novo arginine synthesis averaged 9.2 +/- 1.4 mumol. kg-1.hr-1, indicating that approximately 11% of the plasma arginine flux originates via conversion of plasma citrulline to arginine. Thus, the fraction of the plasma arginine flux associated with NO and also urea synthesis in healthy humans is small, although the plasma arginine compartment serves as a significant precursor pool (54%) for whole body NO formation. This tracer model should be useful for exploring these metabolic relationships in vivo, under specific pathophysiologic states where the L-arginine-NO pathway might be altered.     

Histones associated with non-nucleosomal rat ribosomal genes are acetylated while those bound to nucleosome-organized gene copies are not

Acetylation of histones bound to rat rRNA genes has been studied relative to their organization in chromatin, either as canonical nucleosomes, containing the inactive copies, or as anucleosomal nonrepeating structures, corresponding to the transcribed genes (Conconi, A., Widmer, R. M., Koller, T., and Sogo, J. M. (1989) Cell 57, 753-761). Nuclei from butyrate-treated rat tumor cells were irradiated with a UV laser to cross-link proteins to DNA, and the purified covalent complexes were immunofractionated by an antibody that specifically recognized the acetylated histones. Upon probing with sequences coding for mature rat 28 S RNA, DNA of the antibody-bound complexes was 5-20-fold enriched relative to the total rat DNA. Since the laser cross-links histones to DNA in both active and inactive genes, one cannot distinguish which one of them, or both, are bound to acetylated histones. Alternatively, purified mononucleosomes were immunofractionated, but DNA from the antibody-bound monosomes was not enriched in coding rDNA. Taken together, these results suggest that nucleosome-organized rRNA genes are bound to nonmodified histones and that the acetylated histones are associated with the active, anucleosomal gene copies.     

Focal occlusive disease of the common femoral artery: a report of 20 cases

Occlusive disease localized to the common femoral artery without contiguous involvement of the external iliac and superficial femoral arteries is distinctly uncommon in vascular surgical practice. Twenty patients with focal occlusive disease in 21 common femoral arteries are featured in this report. All except one had severe disabling symptoms: Fontaine classification was stage I in one patient, stage IIb in 13, and stage III in six patients. The probable aetiology, based on clinical features and angiographic observations, was identified as atherosclerosis (nine cases), thromboangiitis obliterans (three) and Takayasu's arteritis (two). Histological features of mucoid vasculopathy, a novel disorder, was seen in one patient while no specific aetiology was evident in five patients. Associated lesions were seen in fourteen patients: aortoiliac in one, femoropopliteal in seven (without any continuity to the common femoral lesion), internal iliac in three and tibial in three. Balloon angioplasty of the common femoral artery lesions was attempted in 14 patients with successful outcome in nine. Three patients (including two with failed balloon angioplasty), underwent thromboendarterectomy and two bypass procedures (iliofemoral, one; femoropopliteal, one). Late reocclusion occurred in one patient each in the angioplasty and surgical groups. There were no procedure-related complications in either group.     

Intravascular histiocytosis

The majority of cases of intravascular lymphomatosis are B-cell lymphomas with only the occasional case being of T-cell type. We report a case of intravascular lymphomatosis in which the proliferating cells were of histiocytic type; the tumour has recurred following treatment.     

Characteristics of lesions of paranasal sinuses in patients with optic chiasm arachnoiditis

The paper provides data on a comprehensive rhinological and x-ray examination of 201 patients suffering from optochiasmal arachnoiditis (OCA). Paranasal affection (as a rule polysinusitis) was disclosed in 75.6% of the examinees. The lesion occurred primarily in the sphenoidal sinuses and frequently combined with ethmoidal labyrinth and maxillary sinus involvement. Rhinological and x-ray symptoms in OCA are rarely prominent giving grounds to physicians for defining it as the syndrome of minor clinical signs. The latter hold importance for diagnosis which enables early cleansing of the paranasal sinuses in combined treatment of OCA.     

A survey of 4478 biopsy specimens of oral lesions

A surgery of 4478 biopsy specimens in dental institute in India was carried out to compare and correlate results obtained from such studies carried out elsewhere. The study revealed that there are more than 150 common and rare oral diseases which are diagnosed and treated by dentists. 13 common diseases comprised majority (60.37%) of the biopsy specimens studied. Of these, tumors (25.53%) and Cysts (14.38%) constituted the majority of the bulk. The study also shows that most of the benign tumors were mesenchymal in origin (almost 5.5:1) while malignant tumors were epithelial (almost 20:1) in origin. Cystic lesions included the most common radicular cyst (7.12%) and the rare hydatid cyst (one case reported). Gingival hyperplasia mainly due to local aetiology, constituted the 3rd largest group. The purpose of this report is to provide some information about the type and frequency of oral lesions usually diagnosed, with the help of histopathological examination in India.     

Randomized comparison of anatomic and electrogram mapping approaches to ablation of the slow pathway of atrioventricular node reentrant tachycardia

OBJECTIVES: The purpose of this study was to prospectively compare in random fashion an anatomic and an electrogram mapping approach for ablation of the slow pathway of atrioventricular (AV) node reentrant tachycardia. BACKGROUND: Ablation of the slow pathway in patients with AV node reentrant tachycardia can be performed by using either an anatomic or an electrogram mapping approach to identify target sites for ablation. These two approaches have never been compared prospectively. METHODS: Fifty consecutive patients with typical AV node reentrant tachycardia were randomly assigned to undergo either an anatomic or an electrogram mapping approach for ablation of the slow AV node pathway. In 25 patients randomly assigned to the anatomic approach, sequential radiofrequency energy applications were delivered along the tricuspid annulus from the level of the coronary sinus ostium to the His bundle position. In 25 patients assigned to the electrogram mapping approach, target sites along the posteromedial tricuspid annulus near the coronary sinus ostium were sought where there was a multicomponent atrial electrogram or evidence of a possible slow pathway potential. If the initial approach was ineffective after 12 radiofrequency energy applications, the alternative approach was then used. RESULTS: The anatomic approach was effective in 21 (84%) of 25 patients, and the electrogram mapping approach was effective in all 25 patients (100%) randomly assigned to this technique (p = 0.1). The four patients with an ineffective anatomic approach had a successful outcome with the electrogram mapping approach. On the basis of intention to treat analysis, there were no significant differences between the electrogram mapping approach and the anatomic approach with respect to the time required for ablation (28 +/- 21 and 31 +/- 31 min, respectively, mean +/- SD, p = 0.7) duration of fluoroscopic exposure (27 +/- 20 and 27 +/- 18 min, respectively, p = 0.9) or mean number of radiofrequency applications delivered (6.3 +/- 3.9 vs. 7.2 +/- 8.0, p = 0.6). With both the anatomic and electrogram mapping approaches, the atrial electrogram duration and number of peaks in the atrial electrogram were significantly greater at successful target sites than at unsuccessful target sites. CONCLUSIONS: The anatomic and electrogram mapping approaches for ablation of the slow AV nodal pathway are comparable in efficacy and duration. If the anatomic approach is initially attempted and fails, the electrogram mapping approach may be successful at sites outside the areas targeted in the anatomic approach. With both the anatomic and electrogram mapping approaches, there are significant differences in the atrial electrogram configuration between successful and unsuccessful target sites.