Periodontal attachment loss associated with proximal tooth restorations

This study documents that periodontal attachment loss is greater adjacent to restored tooth surfaces than adjacent to unrestored tooth surfaces. This finding emphasizes the importance of the prevention of caries and poor restorations.

The radiographic distinction between pericardial and myocardial calcifications

Calcification overlying the left side of the heart on a chest radiograph may involve either the pericardium or, alternatively, the myocardium in association with a left ventricular aneurysm. Distinction between these two conditions can be of great clinical significance. To identify distinguishing features, we reviewed the radiographs and medical records of 29 patients: 14 had proven calcific pericarditis and 15 had proven calcified left ventricular aneurysm. Pericardial calcification was found primarily over the right-sided cardiac chambers (14 of 14 patients) and in the atrioventricular grooves (11 of 14), infrequently over the base of the left ventricle (five of 14), and rarely over the apex of the left ventricle (two of 14). When the left ventricle was involved, there was always more extensive calcification elsewhere in the pericardium. Myocardial calcification occurred predominantly in the apex of the left ventricle (13 of 15 patients), although it was rarely confined to the posterior wall of the left ventricle (two of 15). By noting characteristic sites of calcium deposition, pericardial calcification can be effectively distinguished from myocardial calcification. Isolated calcification in the region of the left ventricular apex, therefore, strongly suggests left ventricular aneurysm.

[Metastatic brain tumor after chemotherapy of ovarian cancer]

A case of brain metastasis in ovarian cancer is reported. Recently cis platin-containing combination chemotherapeutic regimens have improved the prognosis of patients with advanced ovarian carcinoma. Metastasis to the brain in ovarian cancer is very rare. However, the incidence of cerebral metastasis after chemotherapy for ovarian carcinoma seems to be increasing, and this may be related to prolonged survival due to chemotherapy. Thus, neurological examination after chemotherapy with cis platin is necessary to detect metastases to the brain.

Importance of a hydrophobic residue in binding and catalysis by dihydrofolate reductase

A conserved residue at the dihydrofolate binding site of dihydrofolate reductase (EC 1.5.1.3), leucine-54, was replaced with glycine to ascertain the role of this hydrophobic amino acid. The effect of the mutation is both to increase the dissociation rate of dihydrofolate and decrease the rate of hydride transfer thus changing the rate-limiting step in catalysis from product loss (leucine-54) to hydride transfer (glycine-54). The total stabilization by leucine-54 of the transition state for hydride transfer is ca. 10(4)-fold (delta delta G approximately 5.4 kcal/mol) at subsaturating dihydrofolate levels relative to free enzyme despite its location some 10 A from the site of chemical reaction.

Mutagenicities of nitrosated carboline derivatives

Food-borne amines have been considered as the potential precursors of endogenous carcinogenic N-nitroso compounds in humans. A compound which yields a direct mutagen after nitrite treatment was isolated from soy sauce and was identified as 1-methyl-1,2,3,4-tetrahydro-2-carboline-3-carboxylic acid (MTCA) (Wakabayashi, et al., 1983). The mutagenicities of other carboline derivatives such as harman, norharman, harmaline, harmalol, harmine, and harmol were studied. Like MTCA, the nitrosated carboline derivatives showed higher mutagenic activity as compared to their corresponding parent compounds. The demethylated analogue of MTCA, 1,2,3,4-tetrahydro-2-carboline-3-carboxylic acid was synthesized and its nitrosated products were shown to be mutagenic to Salmonella typhimurium TA 100 and TA 98. The potent mutagen Trp-P-2 is a typical 3-carboline derivative. The mutagenicity of Trp-P-2 was suppressed remarkably after nitrosation. Several 3-carboline derivatives also showed the similar property. Nitrosation of MTCA gave several derivatives which were isolated and showed direct mutagenicity to Salmonella typhimurium TA 98. Further characterization of these new carboline derivatives is in progress.

Mediastinal collateral arteries: important vessels in coarctation of the aorta

Mediastinal collateral arteries are usually present in children with coarctation of the aorta or obstruction of the subclavian artery. These arteries, normally bilateral, connect the subclavian artery, costocervical trunk, or supreme intercostal artery to the descending thoracic aorta. They probably represent hypertrophied preexisting normal vessels of an embryologic origin other than persistence of a dorsal aortic root. Radiologists should be aware of the high frequency of these mediastinal vessels in patients with coarctation of the aorta and subclavian obstruction because they indicate a hemodynamically significant lesion.

Chronic tension pneumothorax presumably due to a "ball valve" bronchopleural fistula

We have described an unusual variant of bronchopleural fistula whose ball valve characteristics led to a chronic tension pneumothorax without fluid collection in a postpneumonectomy space.

Anterior chest wall mass in an elderly male

A case of chondrosarcoma arising from the right anterior second rib in an 84-year-old man is described. Radiographic features include amorphous calcification within a chest wall mass. CT findings include calcification and necrosis within the 8 X 8 X 10 cm tumor, and extension into the adjacent lung. The presence of zones of dedifferentiation into fibrosarcoma in the surgically resected tumor indicates a poor prognosis, with a high likelihood of early recurrence and pulmonary metastasis.

Radiographic findings in pulmonary hypertension from unresolved embolism

Pulmonary artery hypertension with chronic pulmonary embolism is an uncommon entity that is potentially treatable with pulmonary embolectomy. Although the classic radiographic features have been described, several recent investigators report a significant percentage of these patients with normal chest radiographs. In a series of 22 patients, no normal radiographs were seen. Findings included cardiomegaly (86.4%) with right-sided enlargement (68.4%), right descending pulmonary artery enlargement (54.5%), azygos vein enlargement (27.3%), mosaic oligemia (68.2%), chronic volume loss (27.3%), atelectasis and/or effusion (22.7%), and pleural thickening (13.6%). Good correlation with specific areas of diminished vascularity was seen on chest radiographs compared with pulmonary angiograms.

Site-specific mutagenesis of dihydrofolate reductase from Escherichia coli

Two site-specific mutations of dihydrofolate reductase from Escherichia coli based on the x-ray crystallographic structure were constructed. The first mutation (His-45----Gln) is aimed at assessing the interaction between the imidazole moiety and the pyrophosphate backbone of NADPH. The second (Thr-113----Val) is part of a hydrogen bonding network that contacts the dihydrofolate substrate and may be involved in proton delivery to the N5-C6 imine undergoing reduction. The first mutation was shown to alter both the association and dissociation rate constants for the cofactor so that the dissociation constant was increased 6-40-fold. A corresponding but smaller (fourfold) effect was noted in V/K but not in V compared to the wild-type enzyme. The second was demonstrated to increase the dissociation rate constant for methotrexate 20-30-fold, and presumably dihydrofolate also, with a corresponding 20-30-fold increase in the dissociation constant. In this case an identical effect was noted on V/K but not in V relative to the native enzyme. Thus, in both mutant enzymes the decrease in binding has not been translated into a loss of catalytic efficiency.

Obscured aortic arch on the lateral view as a sign of coarctation

Forty patients with coarctation of the aorta were compared with 80 normal subjects matched by sex and age. The aortic arch was invisible on the lateral radiograph in 84% of patients preoperatively and 88% postoperatively. Only 6 normal subjects (8%) had a similar finding. The authors conclude that an obscured aortic arch on the lateral view could be a clue to the presence of coarctation. Possible explanations for this phenomenon include (a) dilatation of the brachiocephalic arteries (particularly the left subclavian artery), obscuring the superior margin of the arch; (b) hypoplasia and anteromedial displacement of the distal portion of the arch; and (c) diffuse hypoplasia of the arch combined with focal coarctation.

Unusual radiologic manifestations of bronchogenic cyst

We have presented four cases of bronchogenic cyst, emphasizing the uncommon radiologic manifestations, including air trapping and/or lobulated contour. Two of the cysts were in the lung parenchyma, one in the left hilum adherent to the left lower lobe bronchus, and one in the posterior mediastinum. Recognition of the unusual radiologic features aids in establishing an appropriate differential diagnosis and directing subsequent evaluation.

Limited value of interlaced ECG-gated radiography in the presence of a normal chest radiograph

Twenty-seven patients with normal posteroanterior and lateral chest radiographs, who were undergoing cardiac catheterization because of symptoms strongly suggesting coronary artery disease, also had posteroanterior and lateral interlaced electrocardiogram-gated radiographs made. In 14 patients, the interlaced radiography system underestimated (suggested hypokinesia) the wall motion, which was normal on cardiac catheterization. In two cases the system overestimated the wall motion, in two others it both under- and overestimated the motion, and in only nine cases was the correlation correct. These data suggest that the technique is of limited application, particularly in cases in which the routine chest radiographs are normal.

Cardiac fluoroscopy

The two basic radiologic approaches to heart disease are roentgenography and fluoroscopy. The purpose of this article is to examine the usefulness and limitations of cardiac fluoroscopy in order to put it into proper perspective.

Peripheral middle lobe syndrome

Classically, the middle lobe syndrome has been described as being caused by a central obstruction. Clinical records and radiologic findings were reviewed in 129 patients examined between 1955-1981 who had chronic disease in the right middle lobe and/or lingula. Fifty-eight patients (45%) had no evidence of a central obstructive lesion. The majority were middle-aged women with histories of chronic cough and chest pain. Bronchoscopic and radiologic evaluation served to exclude central lesions. Surgical confirmation was available in 38 patients. Pathologic study showed varying degrees of chronic inflammation, pneumonia, and bronchiectasis. Surgical results were excellent in isolated disease. Chronic atelectasis and pneumonitis of the right middle lobe and/or lingula do not always imply central obstruction. A lack of collateral ventilation is a plausible theory to explain the pathophysiology in such patients.

Adult-onset pulmonary tuberculosis

Medical records and radiographs of 103 adults with primary tuberculosis were reviewed. The shift toward delayed presentation appears to be related to decreasing childhood exposure and an increasing number of compromised hosts. Compared with classic "childhood" tuberculosis, there is a higher incidence of lower-lobe disease, but infiltrates also commonly involve the upper lobe or upper segments of the lower lobe. Adenopathy, cavitation, and tuberculoma are rare. If a pleural effusion is present and tuberculosis is suspected, pleural biopsy is mandatory. Adult respiratory distress syndrome can be a complication, particularly in miliary tuberculosis, and disseminated intravascular coagulopathy usually follows. A normal chest radiograph or clinical improvement of the patient with bed rest and penicillin does not exclude tuberculosis. Increased awareness of adult-onset tuberculosis on the part of radiologists could lead to a more rapid diagnosis and successful management.

Solitary pulmonary metastases in high-risk melanoma patients: a prospective comparison of conventional and computed tomography

A prospective comparison of chest radiography, conventional tomography, and computed tomography (CT) in the detection or confirmation of solitary pulmonary nodules was made in 42 patients with high propensity for pulmonary metastases due to advanced local (Clark level IV or V) or regional malignant melanoma. Unequivocal nodules were revealed by chest radiography in 11 patients, conventional tomography in 16, and computed tomography in 20 patients. Both plain films and tomography in three of these 20 were normal, but follow-up verified pulmonary metastases. Computed tomography detected more pulmonary nodules than conventional tomography in 11 patients in addition to identifying lesions in extrapulmonary sites. Therefore, chest CT is recommended before institution of immunotherapy or surgical removal of a solitary pulmonary melanoma metastasis. Once chemotherapy had been instituted for bulky regional or cutaneous involvement, however, the findings of either conventional or computed tomography were comparable in this study.

Synthesis and separation of diastereomers of deoxynucleoside 5'-O-(1-thio)triphosphates

Treatment of unprotected nucleosides with an excess of phosphorous acid and stoichiometric proportions of N,N'-di-p-tolylcarbodiimide in anhydrous pyridine gives predominantly deoxynucleoside monophosphites and minor amounts of 5' :3'-diphosphites; for deoxyadenosine and deoxyguanosine, the monophosphite products are exclusively 5'-phosphites, whereas for deoxycytidine and thymidine, the yields of the 5'-phosphites are 85% and 92% respectively. Sulfurization of these deoxynucleoside monophosphites with sulfur in the presence of trialkylamines and trimethylsilyl chloride in dry pyridine nearly quantitatively produces deoxynucleoside phosphorothioates. Condensation of these phosphorothioates with pyrophosphate forms diastereomers of the alpha-thio-derivatives of deoxynucleoside triphosphate. The individual diastereomers of each deoxynucleoside 5'-O-(1-thio)triphosphate can be separated, on a preparative scale, by ion exchange chromatography.