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High resolution 1H-NMR at 360 MHz was used to characterize monomeric melittin in aqueous solution. The monomeric form of melittin was found to prevail at 3 mM concentration, pH 3.0, and temperatures between 30 and 90 degrees C, both in the absence of salt and with 6 M guanidium chloride. From comparison with model peptides and studies of the effects of 6 M guanidium chloride and variable temperature on the NMR parameters it was concluded that monomeric melittin is predominantly in an extended flexible form, with the fragments 5--9 and 14--20 more highly structured than the rest of the amino acid sequence. The appearance of a second, low abundant form of monomeric melittin, which is in slow exchange on the NMR time scale with both the more abundant monomeric conformation and aggregated melittin, was attributed to cis-trans isomerism of the peptide bond Leu-13--Pro-14.

Promitochondrial membranes, prepared from Saccharomyces cerevisiae grown anaerobically under different conditions of lipid supplementation, have been examined by PMR spectroscopy. Promitochondria from cells cultured anaerobically in media containing both unsaturated fatty acid and sterol supplements, or containing unsaturated fatty acid alone, yield high resolution spectra similar to those which are characteristic of aerobic mitochondria. By contrast, promitochondrial membranes from cells grown only with sterol supplementation in order to deplete unsaturated fatty acid and total phospholipid content of the organelles, yielded PMR spectra which were very substantially broadened. These spectra are similar to those obtained with rat liver mitochondria. PMR spectra of promitochondria from each cell type dispersed in trifluoroacetic acid, or of extracted lipids or residual proteins similarly dispersed, were different only in detail. It appears, therefore, that in the native state membranes of unsaturated fatty acid-depleted promitochondria are structurally different from promitochondria of the other two cell types. The difference may be a consequence of altered lipid-to-protein ratios, and thus of changes in the extent of lipid domain formation in the membranes of these organelles.

Nine strains of cariogenic Streptococcus mutans and two strains of Streptococcus sanguis were tested for their ability to form hydroxyapatite. The cells were examined by X-ray diffraction and electron microscopy for apatite crystals after growth in a synthetic calcification medium. Each of the test isolates, except for one strain of S. sanguis, produced intracellular mineral. Two strains of S. mutans formed both intra- and extracellular crystals. There was no apparent relationship between calcifiability and serotype.

Fourteen lots of thymolphthalein monophosphate (TMP), disodium salt, obtained from 10 commercial suppliers were compared spectrophotometrically at 445 and 595 nm, liquid-chromatographically with monitoring at 254 nm, and enzymically by measurements of activity of prostatic acid phosphatase in human serum. Eight lots were classified as "unacceptable," six as "acceptable." Spectrophotometric testing revealed four lots with excessive thymolphthalein and three lots with grossly deficient amounts of TMP. In general, the chromatographic results paralleled those obtained by spectrophotometry, and both results correlated well with enzymic activity. Changing water content in this hygroscopic salt was a major problem, which resulted in great uncertainty as to the formula weight and therefore as to the moles of TMP actually taken. From these studies, specifications for high-quality TMP were determined. The critical importance of simultaneous enzymic activity measurements in comparisons with other "acceptable" lots in defining an adequate TMP substrate is stressed. Use of these specifications for selecting TMP for acid phosphatase activity measurements should improve intra- and inter-laboratory analytical performance.

Injury to surrounding tissues during radiotherapy for oral cancer can have devastating physical and psychologic consequences for the patient. Oral complications include xerostomia, dental decay, mucositis, taste loss, osteoradionecrosis, infection, and trismus. In many instances, these problems can be eradicated or controlled with appropriate treatment.

Potentially cariogenic microorganisms cultured from noncarious and carious root and coronal (enamel) surfaces were quantitatively compared in patients 22 to 84 years of age (mean, 52 years). We collected 150 plaque specimens from 26 in situ teeth with initial root lesions and from 25 extracted teeth with advanced root lesions. The frequencies of isolation of Streptococcus mutans, Actinomyces viscosus, and Lactobacillus spp. were, respectively, 94, 72, and 51% at the noncarious root site; 98, 71, and 54% at the root lesion; 84, 61, and 44% at the noncarious enamel site; and 100, 66, and 90% at the enamel lesion. The streptococci made up the largest mean proportion of the total anaerobic cultivable microflora, ranging from 31.2% at the noncarious enamel site to 37.6% at the root lesion, while S. mutans varied between 18% at the noncarious enamel and root surfaces and approximately 24% at both the enamel and root lesions. The proportion of actinomyces ranged from 12.3% at the root lesion to 23.6% at the noncarious root site, while A. viscosus varied from 7.8% at the root lesion to 15.1% at the noncarious root site. The largest mean proportion of lactobacilli (4.2%) was recovered at the enamel lesion site. Proportions of Candida spp. made up less than 0.1% at all sites. Proportions of microorganisms did not differ significantly between noncarious enamel and root sites, but the noncarious coronal and root sites had higher (P less than 0.05) proportions of actinomyces than did the root lesion. Also, enamel lesions had a greater (P less than 0.05) percentage of Lactobacillus spp. than did root lesions. The number of streptococci recovered from the root lesion was greater (P less than 0.01) than the number of actinomyces at the same site. S. mutans was recovered from initial root lesions in greater numbers (P less than 0.001) than were actinomyces and lactobacilli. The number of S. mutans recovered at the initial root lesions was greater (P less than 0.01) than that recovered from the advanced root lesions.

A new edition of the AFGL trace gas compilation is now available. Absorption line parameters of positions, intensities, and halfwidths are given for the major bands of thirteen gases covering the spectral region from 0 to 10,000 cm(-1). In addition to updating the original gases (NO, SO(2), NO(2), and NH(3)), the molecules HNO(3), OH, HF, HC1, HBr, HI, CIO, OCS, and H(2)CO have been added to the compilation. The sources for the additions and modifications are described.

Previously, the size and stoichiometry of mixed micelles of perdeuterated dodecylphosphocholine and melittin were characterized and the 1H NMR spin systems of most amino acid residues of micelle-bound melittin identified. One- and two-dimensional 1H-1H Overhauser experiments have now been used to obtain qualitative information on intramolecular proton-proton distances. These data show that the N-terminal and the C-terminal segments of melittin form two spatially distinct, compact domains; using lipid spin labels these could be located near the micelle surface. For the C-terminal domain a detailed conformation was determined by using the distance contraints from the Overhauser studies as input for a distance geometry algorithm.

This bulletin examines the narrowing margin between global food production and population growth. Between 1950 and 1971, world grain production nearly doubled and per capita production increased 31%. During the 1970s, gains in output barely kept pace with population growth, consumption/person declined in sub-Saharan Africa and parts of Asia, food prices were volatile, and over 100 food deficit countries came to depend on the exportable surplus of North America, now the only major grain exporting region. The world fish catch levelled off in the early 1970s and beef production, still dependent mainly on grassland grazing, levelled off in the mid-1970s. With little new land left to plow, satisfying increased food demand now depends on sharp increases in yields on existing crop land. Worldwide, this effort is hampered by loss of topsoil and irrigated land, conversion of cropland to nonfarm uses, rising energy costs, inefficient agrarian structures, particularly in the Soviet Union, the falling yield response to chemical fertilizers in agriculturally advanced countries, and the emerging competition between food and agriculturally based energy crops. Green Revolution successes in some developing countries deomonstrate that, given the right inputs, 3rd world farmers can increase crop yields dramatically. Feeding the world's poor also requires more equitable income and food distribution, including a reduction in the proportion of grain and fish consumed indirectly as livestock products by the affluent. Most important in meeting food needs on a finite planet is braking population growth. The author concludes that every effort should be made to stabilize world production at abour 6 billion by 2020, rather than 10.5 billion by 2110, as is now projected by the UN.

The primed lymphocyte test (PLT) was utilized to investigate the biologic relationship between alloantigens and soluble environmental antigens. Human lymphocytes primed in vitro to the soluble antigens Candida (CAN), Tetanus (TET), or Purified Protein Derivative of Tuberculin (PPD) gave a strong proliferative response when restimulated with the initial soluble antigen in the presence of irradiated peripheral blood lymphocytes (PBL) acting as antigen-presenting cells (APC). Surprisingly, the soluble antigen-primed cells as well as alloantigen-primed cells responded to other soluble antigens in the presence of APC. By testing primed cells with supernatants derived from irradiated lymphocytes plus soluble antigen, it was apparent that the responses observed were in part due to stimulation by a soluble factor produced by the irradiated "APC" in response to the soluble antigen rather than to recognition of widespread cross-reactivity by the primed cells. This "nonspecific" factor production could be diminished by increasing the dose of irradiation to the APC or by using a T lymphocyte depleted- (SRBC-E-) APC population. In addition, certain antigen-reactive T cell clones did not respond to the nonspecific factor to the same degree as the primed bulk cultures. Nevertheless, the recognition of nonspecific stimulation induced by factors produced by irradiated lymphocytes is critical in the interpretation of primed lymphocyte responses to alloantigens or soluble antigens.

Rapid loss of the electron spin resonance signal from a variety of spin labels is observed when ferricytochrome c or metmyoglobin are combined with lipids. Evidence is presented that this loss of signal can be used as a sensitive method to study lipid oxidation catalyzed by heme proteins. Under aerobic conditions and with lipids which bind the heme protein, the kinetics of the oxidation process as observed by the spin label method are identical to the kinetics previously observed by measurements of oxygen uptake. Use of pre-oxidized lipids under anaerobic conditions indicates that cytochrome c reacts with a product of lipid oxidation. Kinetic studies of the anaerobic reaction indicate that cytochrome c reacts rapidly with lipid oxidation products in membrane areas far larger than the area occupied by cytochrome c, implying rapid transport of reactive species within the membrane interior in directions parallel to the membrane surface. Under anaerobic conditions, reaction of cytochrome c with lipid oxidation products appears to produce a relatively long lived (hours) species located in the hydrophobic portion of the membrane, which is capable of subsequent reaction with lipid-soluble spin labels.

Detecting pulmonary metastasis is important when planning surgical therapy, radiotherapy, or chemotherapy in patients with known malignancy. A series of 91 patients was studied by both whole lung tomography and computed tomography (CT) of the lungs. More pulmonary nodules were detected with CT than with whole lung tomography in 32 (35%) of the patients. Of the 91 patients in the study, 31 had resection of some or all of the pulmonary nodules. In 27 patients, the nodules were primary or metastatic malignant lesions. Bilateral pulmonary nodules were detected with CT in 13 patients when whole lung tomography had demonstrated nodules in only one lung. CT has replaced whole lung tomography as the method preferred by the authors for detecting pulmonary nodules in selected patients at risk to develop pulmonary metastasis.

Fractionation of serum samples from head and neck cancer patients and their assay for agglutination activity toward oral microorganisms showed that the activity was derived from IgG, 7S IgA, 10S (dimeric) IgA, and IgM, with considerable activity in the 10S IgA region. These findings probably account for the lack of a significant relationship among levels of individual serum immunoglobulins, agglutination titers, and caries activity presented in an earlier study. Conversely, most of the agglutinating activity in fractionated saliva was attributed to 11S IgA, presumably secretory IgA, with some activity from a 19S substance and, in the caries-active patients, from a higher molecular weight factor. These data correspond to positive correlations between saliva IgA levels, agglutination titers, and absence of caries in these patients.

Patients with pseudolymphoma, well-differentiated lymphocytic lymphoma, and lymphocytic interstitial pneumonitis were studied. Diagnoses were confirmed by recently developed immunochemical staining techniques. Radiographic findings in pseudolymphoma were different from those in well-differentiated lymphocytic lymphoma, and clinical findings in lymphocytic interstitial pneumonitis were different from those in the other two types of lesions. The interstitial infiltrate of lymphocytic interstitial pneumonitis had two patterns: basilar with an alveolar component and diffuse with associated honeycombing. Pseudolymphoma and lymphocytic interstitial pneumonitis are being polyclonal inflammatory processes without malignant potential. Well-differentiated lymphocytic lymphoma, a monoclonal neoplasm, often has an indolent course.

We have developed a new research tool for the study of S-adenosylmethionine (AdoMet) metabolism by cloning the coliphage T3 AdoMet hydrolase (AdoMetase; EC 3.3.1.2) gene into the M13mp8 expression vector. The recombinant bacteriophage clones expressed an AdoMetase activity in Escherichia coli like that found in T3-infected cells. High levels of AdoMetase expression impaired AdoMet-mediated activities such as dam and dcm methylase-directed DNA modifications and the synthesis of spermidine from putrescine. Expression vectors containing the cloned AdoMetase gene thus provide an alternate approach to the use of chemical inhibitors or mutants defective in AdoMet biosynthesis to probe the effect of AdoMet limitation.

Assignments have been obtained for most of the H-NMR lines of melittin bound to fully deuterated dodecylphosphocholine micelles by combined use of two-dimensional spin echo correlated spectroscopy and one-dimensional NMR methods. Nuclear Overhauser enhancement measurements showed that the mobility of the entire polypeptide chain is reduced by binding of melittin to the detergent micelle and that the amino-terminal and carboxy-terminal halves of the primary structure constitute separate, compact domains within the conformation of micelle-bound melittin. p2H titration experiments showed that the presence of positive charges on the four amino groups of melittin had little influence on the conformation of the micelle-bound polypeptide. Titration of tetrameric melittin with detergent provided evidence that melittin assumes similar conformations as a self-aggregated tetramer and as a monomer bound to micelles.

A 73-year-old woman with a two-year history of recurrent episodes of respiratory distress is described. The finding of an elevated triglyceride value of 23.4 mmol/L (2072 mg/dL) and a normal cholesterol value in her sputum led to the correct diagnosis of chyloptysis after lymphangiography was performed. It is thought that congenital incompetence of the lymphatic valves was the cause of chyloptysis.

We used the sequence-specific endonucleases EcoRI, SmaI, BamHI, HsuI, and HaeIII as identification tools in following the conjugal transfer of the well-studied R plasmids Sa, R388, RP4, and R6K. Transfers were both intergeneric and intrageneric. Plasmid fingerprints were generated from both single- and combination-enzyme digests. The Sa transconjugants yielded plasmids showing consistent fingerprints for each of the respective endonucleases used, whereas the three other R-plasmid transconjugants showed fingerprint changes.

In a new approach for the determination of polypeptide conformation, experimental data on intramolecular distances between pairs of hydrogen atoms obtained from nuclear Overhauser enhancement studies are used as input for a distance geometry algorithm. The algorithm determines the limits of the conformation space occupied by the polypeptide chain. The experimental data are used in such a way that the real conformation should in all cases be within these limits. Two important features of the method are that the results do not depend critically on the accuracy of the distance measurements by nuclear Overhauser enhancement studies and that internal mobility of the polypeptide conformation is explicitly taken into consideration. The use of this new procedure is illustrated with a structural study of the region 19-27 of glucagon bound to perdeuterated dodecylphosphocholine micelles.

The levels of specific proteins and electrolytes in stimulated whole saliva were monitored in Skylab crew members before and after each mission. With few exceptions, mission-associated compositional changes in saliva were relatively minimal. There were no changes in(formula see text), Cl-, albumin, or IgG concentrations. There were slight decreases in total protein coinciding with moderate saliva flow rate increases immediately before and after each flight. Other changes included diminutions in Na+ and lysozyme, and elevations in Mg++ and IgA. The IgA increase was the most pronounced mission-associated change observed.

Fourier transform 1H nuclear magnetic resonance (NMR) experiments at 360 MHz using convolution difference techniques to improve the spectral resolution were employed to investigate the resonances of the lysyl residues in bovine pancreatic trypsin inhibitor. The observations in both native protein and in chemically modified protein containing Nepsilon-dimethyllsysine show that three of the four lysines extend predominantly freely into the solvent, whereas lysine-41 is involved in an intramolecular interaction with tyrosine-10. Since in the single crystal structure tyrosine-10 is involved in an intermolecular interaction with arginine-42 of the neighboring protein molecule, the NMR data thus reveal a local conformation difference for bovine pancreatic trypsin inhibitor in solution and in the crystalline form which appears to result primarily from intermolecular interaction in the crystal lattice.

Among 69 cases of thymoma, 16 of the lesions were not detected immediately in the first Mayo Clinic posteroanterior radiographs. Often they resembled right heart enlargement, their margins overlay the shadow of the right heart or hilus, or they were too small to be seen. A helpful sign was lobulation of the mass. Used selectively within the series, lateral views, computed tomography (CT), oblique views guided by fluoroscopy, and plain-film tomography contributed variously to accuracy of diagnosis and description. Until a determination is made, application in the order listed is recommended. Lateral tomograms often showed details of small, isolated abnormalities in the anterior mediastinum. Although CT did not reveal any lesions that were not suspected from other radiographic studies, it did show important anatomic relations. Early detection is important: 29% of the lesions were malignant, including 22% of those smaller than 5 cm. However, diagnosis was delayed after initial radiologic investigation (either elsewhere or at Mayo Clinic) in 17 cases (25% of the series), for intervals averaging 41 months. None of the imaging techniques was accurate in predicting malignancy, although CT best demonstrated adherence and invasion.

Proteolipid is known to initiate calcification in vitro. Apoprotein and phospholipid components of proteolipid from five of 14 calcifiable S. mutans specimens were characterized. The apoproteins contained 16 amino acids with calculated percent polarities ranging from 32.0 to 45.2. The acidic phospholipids were cardiolipin, mono- and diphosphoinositides, and phosphatidylserine. Neutral lipids, phosphatidylethanolamine and phosphatidylcholine, were also found. The latter were the most abundant in all isolates. Appropriate hydrophobic proteins and acidic phospholipids in the proteolipids accounted for S. mutans calcifiability.

Twelve consecutive wk of daily five-minute topical applications of 1% NaF gel by non-cancer control subjects did not significantly affect plaque concentrations of Streptococcus mutans or Lactobacillus spp. Plaque F- levels increased 150% (P less than .001), while production of acetate and lactate decreased 40% (P less than .007) and 66% (P less than .001), respectively. Long-term (12 wk to more than five yr) fluoride gel use by post-irradiation xerostomic cancer patients was associated with increases in plaque F- and decreases in acidogenesis similar to those observed in the control subjects. Plaque concentrations of cariogenic organisms increased during the first yr of radiation-induced xerostomia and fluoride gel use, before starting to decline. Although sustained fluoride treatment increased (P less than .001) the ratio of fluoride-resistant to fluoride-sensitive strains, the number of patients harboring detectable S. mutans was diminished (P less than .001).

Findings from the first 430 CT examinations of the thorax performed at the Mayo Clinic were compared with results of film studies and the most certain later diagnoses in the same cases. Results were analyzed by disease and by mediastinal compartment. CT was superior in staging bronchogenic carcinoma, detecting abnormal masses, and in demonstrating mediastinal normally when plain films were equivocal. It generally gave clear delineations of lesions and distinguished them better from normal structures, and, in correlation with clinical data, it was more accurate in suggesting whether they were benign or malignant.

A longitudinal study was performed to assess the effects of radiation-induced xerostomia on the human oral microflora. Pronounced microbial population shifts were found in each of five intraoral sites tested. Cariogenic microorganisms gained prominence at the expense of noncariogenic microorganisms in concert with the saliva shutdown. These changes occurred before the onset of clinical caries irrespective of whether or not a topical fluoride gel was used as a caries preventive.

To understand better the characteristics of the coliphage T3 S-adenosyl-L-methionine (AdoMet) hydrolase (AdoMetase, E.C. 3.3.1.2) and its expression in phage-infected Escherichia coli, we determined the DNA sequence of the cloned gene and its surrounding ribonuclease (RNase) III mRNA transcript processing sites. The AdoMetase gene contains two in-frame protein translation initiation sites specifying peptides 17105 and 13978 daltons in size. Both proteins terminate at the same ochre codon making the shorter peptide identical to the carboxy terminal 82% of the 17 kd protein. Our data explain the existence of two AdoMetase-related peptides in preparations of the purified enzyme as well as identify sequences that might serve to regulate the enzyme's expression. Comparisons between this T3 sequence and the homologous 0.3 gene region of the closely related coliphage T7 show both the nucleotide and amino acid sequences to be unrelated. The RNase III mRNA processing sites that bracket these genes in T3 and T7 are highly conserved in both their primary and secondary structures.

Agglutination titers in 444 saliva and 481 serum samples from 36 head and neck cancer patients and 16 control subjects were determined against formalinized cellular antigens of Streptococcus and Lactobacillus species. Saliva agglutination titers were significantly higher in cancer patients before radiotherapy than in control subjects. Changes in specific saliva agglutination titers to oral isolates following radiotherapy reflected changes in saliva IgA and post-irradiation caries activity. Patients with no post-irradiation caries activity had significantly higher saliva agglutination titers to S. mutans, S. sanguis, and L. fermenti, lower plaque S. mutans counts, and higher saliva IgA levels than those with post-irradiation caries activity. Serum agglutination titers were unrelated to either serum immunoglobulin levels, microbial counts, or caries activity.

Saliva and serum electrolyte concentrations were monitored in 30 patients given a course of xerostomia-producing cancer radiotherapy. The mean flow rate of stimulated whole saliva decreased 83.3% during a 6-week treatment period. The striking reduction in saliva output was accompanied by significant increases in saliva Na+, Cl-, Ca++, Mg++ and Prot.- concentrations and by a decrease in saliva HCO3- content. The xerostomic saliva was more concentrated and had a greater salinity than the pretreatment saliva in each instance. In contrast, none of the serum electrolytes measured was significantly altered by the subtotal salivary shutdown.

A phage-mediated transducing system was used in studying certain physiological characteristics of S. lactis C2 wild type, lactose-negative mutants, and lactose-positive transductants. Lac(-) mutants, obtained by acriflavine treatment of the wild type, were similar to the wild type in all characteristics tested except they lacked beta-D-phosphogalactoside galactohydrolase (beta-Pgal) and could not transport [(14)C]lactose; they also had approximately 10% of the proteolytic ability than wild-type cells. The lactose-fermenting characteristic was transduced from the wild type to Lac(-) mutants. The Lac(+) transductants obtained were similar to the wild-type parent with respect to lactose fermentation and level of beta-Pgal activity (0.186 U of protein per mg). These transductants, however, had not regained full proteolytic ability and were similar to the Lac(-) mutant in this respect. Lactic acid production of the transductants in milk was approximately two-thirds that of the wild type. Data suggest that both the lactose-fermenting and proteolytic characters are carried on extrachromasomal particles (plasmids).

A simple technique has been devised for preparing ethylene-vinyl acetate copolymer microspheres containing macromolecular drugs. Beads with good sphericity were formed by a simple extrusion process that can easily be repeated by any laboratory without special equipment. The extruded droplets gelled on immediate contact with cold ethanol in a dry ice-ethanol bath. The ethanol also served to remove the solvent and harden the microspheres as they warmed to room temperature. Release of bovine serum albumin followed the expected trends, i.e., initial linearity with the square root of time and faster release rates with greater drug loading.

Fifty-five-degree oblique hilar tomography is an accurate and simple means of evaluating hilar anatomy and pathology. It is of most value in proving the hilum to be normal in cases in which plain chest roentgenograms suggest a hilar lesion. It is accurate in differentiating hilar adenopathy from hilar masses and in both of these it is helpful in determining the extent and bilaterality of the disease process. Unfortunately, granulomatous infiltrates within the hilum cannot be differentiated from tumor. The procedure is of limited value in the presence of diffuse perihilar pulmonary fibrosis, and at this time caution must be advised in the interpretation of small, unilateral, ill-defined hilar densities as tumors.

In vivo release rates of a macromolecule from an ethylene-vinyl acetate copolymer have been shown to be indistinguishable from those of identical implants tested in vitro. The studies were conducted for approximately 2 months, and two different techniques were used to assess release rates. One of these techniques, using [3H]inulin as a marker, may be particularly useful in future studies assessing in vivo release rates from drug delivery systems. The appearance of [3H]inulin in the urine of rats bearing implants allowed continuous monitoring of release. A histological evaluation of tissue sections surrounding polymer implanted for 7 months showed no inflammatory cell reaction.

Ribonucleic acid (RNA) synthesis was examined in cold-shocked Bacillus subtilis cells. The cells were grown to mid-log stage, harvested, and cold shocked. RNA synthesis was monitored by the incorporation of [3H]uridine triphosphate or [alpha 32P]adenosine triphosphate into trichloroacetic acid-precipitable material in the presence of all four nucleoside triphosphates. The inhibition of RNA synthesis in cold-shocked cells by lipiarmycin, ethidium bromide, rifampin. or streptolydigin was analyzed using mutant or wild-type cells. Also examined were the effects of temperature, salt concentration, and the addition of polyamines or highly phosphorylated nucleotides. In ultraviolet-irradiated and cold-shocked cells, RNA wynthesis decreased to low levels. The addition of exogenous phi 29 or TSP-1 template to these cells caused a 13- to 20-fold increase in RNA synthesis, as monitored by trichloroacetic acid-precipitable counts. RNA synthesized in the presence of phi 29 deoxyribonucleic acid (DNA) hybridizes mainly to EcoRI fragments A and C of phi 29 DBA, These two fragments direct transcription by purified RNA polymerase in vitro and hybridize to early phi 29 DNA produced in vivo. Our results with TSP-1 DNA in this system indicated that the RNA produced hybridizes to the same fragments as early RNA produced in vivo. Plasmic pUB110 DNA was not transcribed in this system.

Pulp tissue was obtained from clinically intact third molars and premolars, and from teeth affected by caries and periodontal disease. After incubation and homogenization, supernatants were centrifuged, sampled and assayed for lymphocyte activating factor-like activity using the thymidine-incorporated D10.G4.1 cell-line assay. Significantly higher levels of mitogenic activity were found in the pulp supernatants of symptomatic carious teeth, and in those of third molars with attendant pericoronitis, than in pulps from symptomatic and asymptomatic periodontally affected teeth and asymptomatic third molars and premolars. As both interleukin-1 (IL-1) and interleukin-2 (IL-2) may be involved in the proliferation of D10.G4.1 cells, supernatants from carious pulps were further tested for IL-2 activity using murine natural killer (NK) cells. Those that had elicited a proliferative response of D10.G4.1 cells did not enhance NK proliferation, indicating that the factor responsible for clonal replication of D10.G4.1 cells was IL-1. To confirm the presence of IL-1, immunohistochemistry using a monoclonal antibody to IL-1 was performed on frozen and paraffin-embedded sections of pulps from each group. IL-1 was immunolocalized within cells in pulps from the caries symptomatic group. The cell type producing IL-1 was further characterized as an alpha-naphthyl-acetate-esterase-positive macrophage within the connective tissue stroma of pulps from the caries symptomatic group. This novel demonstration of IL-1 and IL-1 producing cells in human dental pulp indicates the involvement of this mediator of inflammation in dental disease.

The role of magnetic resonance imaging (MRI) in the evaluation of thoracic disease is emerging amidst much debate and study. Recent technical advances have led to new applications of this modality, and a reappraisal of previous conclusions seems warranted. This article reviews our 5 1/2 years' experience with thoracic MRI.

An arteriovenous fistula between the systemic and pulmonary circulations may be congenital, as in bronchopulmonary sequestration, or the communication may be acquired. Inflammatory disease, trauma, and, rarely, neoplasm have been implicated as possible causes of acquired communications. We describe a patient who had a systemic artery-to-pulmonary vein fistula that was secondary to a recurrent sarcoma of the chest wall. Review of the literature failed to reveal a previous report of a similar case.