The effects of nutrition-induced abnormal food metabolism in the Southern Plains woodrat (Neotoma micropus): comparisons of variations of the Western diet.

We investigated the effects of several modifications of the Western diet on a medium-sized rodent, Neotoma micropus, that lives in the area of the wildland-urban interface. We conducted a laboratory study of the response of N. micropus to high fat-high fructose (HFHF), high fat-high sucrose (HFHS), high fat-low sugar (HFLSu) and control (low fat-low sugar) diets. We found a significant increase in hepatic lipid deposition and a significant decrease in podocytes in those animals that consumed the HFHF and HFLSu diets compared to those on the HFHS and control diets. We found no significant differences in Bowman's space or hepatic collagen formation. We predict that N. micropus in the wild, with access to anthropogenic resources, will show similar effects as a result of the consumption of anthropogenic resources.

Laryngopharyngeal reflux: a modern day "great masquerader".

Laryngopharyngeal reflux is a new term given to gastroesophageal reflux leading to atypical symptoms in the upper aerodigestive tract. The manifestations of laryngopharyngeal reflux are varied and include chronic hoarseness, globus pharyngeus, sore throat, chronic cough, asthma, paroxysmal laryngospasm, and other less common symptoms. Making the diagnosis requires accurate history taking and can be confirmed by fiberoptic examination of the pharynx and larynx, as well as by ambulatory esophageal and pharyngeal pH monitoring. Stepwise treatment regimens are very effective in treating this condition, which exacerbates or imitates many seemingly unrelated disorders.

A 1H-NMR determination of the solution structure of the A-chain of insulin: comparison with the crystal structure and an examination of the role of solvent.

The 1H-NMR chemical shift assignments for the oxidized A-chain of bovine insulin have been determined in aqueous and 30% trifluoroethanol/water solutions. Analysis of the observed medium-range nuclear Overhauser effects indicates that in aqueous solution significant populations of the peptide exist, with a 3(10)-helical conformation over residues 12-17. This region corresponds to helix A (13-20) in the crystal structure of the 2 Zn insulin hexamer. In 30% TFE solution, the NOE data are supportive of a random coil conformation throughout the peptide.

Harvey ras (H-ras) point mutations are induced by 4-nitroquinoline-1-oxide in murine oral squamous epithelia, while squamous cell carcinomas and loss of heterozygosity occur without additional exposure.

Tumorigenesis is a multistep genetic process requiring several somatic mutations for neoplastic transformation. These mutations appear to be sequential, random, and independent events. However, we find linked, nonrandom ras mutations occurring during 4-nitroquinoline-1-oxide-induced tumorigenesis months after exposure to the carcinogen had ceased. The carcinogen had been topically applied to the oral cavity of CBA mice for 4 to 16 weeks. Dysplasia developed after 24 weeks, and carcinoma in situ and squamous cell carcinoma developed after 28 weeks. H-ras mutations were detected in 13 of 25 tissue specimens (10 of 14 invasive carcinomas and 2 of 4 carcinoma in situ, 1 of 5 dysplastic tissue, and 0 of 2 normal tissues). Approximately one-half of the tumors had G to A point mutations at codon 12 of the cellular H-ras proto-oncogene on mouse chromosome 7. None had codon 11, 13, or 61 mutations. Loss of heterozygosity occurred in 5 of 14 invasive cancers. Larger invasive squamous cell carcinomas consistently lost the wild-type allele, whereas preneoplastic lesions and small tumors were heterozygous for ras. This suggests a causal relationship between carcinogen treatment, H-ras activation, and initiation of tumorigenesis. The wild-type allele in mouse chromosome 7 is lost with the progression of tumorigenesis long after exposure to the carcinogen. Thus, loss of heterozygosity of the ras gene appears to occur without multiple carcinogen-induced mutations, i.e., as a result of a cascade of events induced by an earlier ras mutation.

4NQO carcinogenesis: a mouse model of oral cavity squamous cell carcinoma.

BACKGROUND: A murine model of oral cavity carcinogenesis is needed to study the molecular aspects of malignant transformation. 4-Nitroquinoline-1-oxide (4NQO), a water-soluble carcinogen, produces squamous cell carcinoma in rodents. Protocols were designed to investigate the temporal aspects of neoplastic transformation. METHODS: 4NQO was applied topically to mouse palates for up to 16 weeks. Mice were observed and killed from 24 to 49 weeks. RESULTS: A spectrum of lesions ranging from atypia to moderately differentiated invasive squamous cell carcinoma (SCC) was produced. The severity of the lesions corresponded to the duration of treatment and the length of observation. There was no gross or microscopic evidence of an inflammatory reaction to 4NQO. The lesions were focal and normal mucosa predominated in the treated mice. CONCLUSION: 4NQO reliably produced preneoplastic and malignant oral cavity lesions, which morphologically and histologically mimic human head and neck cancer. Lesions develop long after 4NQO exposure and without an inflammatory response. Thus, the model should be useful for molecular analysis of neoplastic transformation.

15N-labeled tRNA. Identification of 4-thiouridine in Escherichia coli tRNASer1 and tRNATyr2 by 1H-15N two-dimensional NMR spectroscopy.

Uridine is uniquely conserved at position 8 in elongator tRNAs and binds to A14 to form a reversed Hoogsteen base pair which folds the dihydrouridine loop back into the core of the L-shaped molecule. On the basis of 1H NMR studies, Hurd and co-workers (Hurd, R. E., Robillard, G. T., and Reid, B. R. (1977) Biochemistry 16, 2095-2100) concluded that the interaction between positions 8 and 14 is absent in Escherichia coli tRNAs with only 3 base pairs in the dihydrouridine stem. We have taken advantage of the unique 15N chemical shift of N3 in thiouridine to identify 1H and 15N resonances for the imino units of S4U8 and s4U9 in E. coli tRNASer1 and tRNATyr2. Model studies with chloroform-soluble derivatives of uridine and 4-thiouridine show that the chemical shifts of the protons in the imino moieties move downfield from 7.9 to 14.4 ppm and from 9.1 to 15.7 ppm, respectively; whereas, the corresponding 15N chemical shifts move downfield from 157.5 to 162.5 ppm and from 175.5 to 180.1 ppm upon hydrogen bonding to 5'-O-acetyl-2',3'-isopropylidene adenosine. The large difference in 15N chemical shifts for U and s4U allows one to unambiguously identify s4U imino resonances by 15N NMR spectroscopy. E. coli tRNASer1 and tRNATyr2 were selectively enriched with 15N at N3 of all uridines and modified uridines. Two-dimensional 1H-15N chemical shift correlation NMR spectroscopy revealed that both tRNAs have resonances with 1H and 15N chemical shifts characteristic of s4UA pairs. The 1H shift is approximately 1 ppm upfield from the typical s4U8 resonance at 14.8 ppm, presumably as a result of local diamagnetic anisotropies. An additional s4U resonance with 1H and 15N shifts typical of interaction of a bound water or a sugar hydroxyl group with s4U9 was discovered in the spectrum of tRNATyr2. Our NMR results for tRNAs with 3-base pair dihydrouridine stems suggest that these molecules have an U8A14 tertiary interaction similar to that found in tRNAs with 4-base pair dihydrouridine stems.

Improvement of positive blood culture detection by agitation.

To evaluate the advantages of agitation in reducing the detection time and increasing the recovery rate of positive blood cultures, 1,000 three-bottle sets of tryptic soy broth on adult inpatients were analyzed. Two bottles were transiently vented, one of which was agitated (250 rpm) for 7-19 hr at 35 degrees C. The other vented bottle and the anaerobic bottle were incubated stationary at 35 degrees C. Smears and subcultures were performed 7-19 hr after collection on both agitated and nonagitated vented bottles. Subcultures were done on all bottles at 72 hr and smears were performed on the anaerobic bottle. There were 137 of 1000 (13.7%) positive cultures from 90 patients. The agitated bottle detected 112 of 137 (81.8%) positive cultures, was the first or only means of detection in 57 of 137 cultures (41.6%), and was the only positive bottle in 30 of 137 (21.9%) cultures. The nonagitated vented bottle detected 89 of 137 (65.0%) of positive cultures and was the only means of detection in 13 of 137 (9.5%), but was never the first means of detection. The anaerobic bottle detected 76 of 137 (55.5%) of positive cultures, was the first or only means of detection in 11 of 137 (8.0%), and was the first means of detection in one of 137 (0.7%) cultures. When both the agitated and nonagitated bottle were positive, the agitated bottle was positive on the average 35 hr earlier. We conclude that agitation of the vented bottle in a conventional blood culture system significantly decreases the detection time of positive blood cultures and increases the number of positive blood cultures detected.

Multiple quantum two-dimensional 1H--15N nuclear magnetic resonance spectroscopy: chemical shift correlation maps for exchangeable imino protons of Escherichia coli tRNAMetf in water.

A procedure based on multiple quantum two-dimensional nuclear magnetic resonance spectroscopy is described for generation of 1H--15N chemical shift correlation maps. The method is used to obtain 15N chemical shifts for the exchangeable imino protons in 1H--15N units of site-specifically labeled Escherichia coli tRNAMetf in water. The high sensitivity and excellent chemical shift dispersion of the multiple quantum two-dimensional technique make it ideally suited for studying protonated nitrogens by NMR.

Rapid detection of positive blood cultures.

A study of 16,108 blood cultures investigated the value of performing early smears in addition to the inspection of early subcultures after 12 h of incubation. The early smear and subculture detected 44.6% of 1,236 positive cultures; of those detected by the early subculture, 57.3% grew after 12 h of incubation.

Organizational career stage as a moderator of the satisfaction-performance relationship.

The relationship between performance and dimensions of job satisfaction is studied among 132 employees of a public agency located in a large southwestern city. The results of this study indicate that the relationship between performance and a particular dimension of job satisfaction may be a function of an individual's career stage within the organization.

Proton nuclear magnetic resonances study of bleomycin in aqueous solution. Assignment of resonances.

The 1H NMR spectrum of the glycopeptide antineoplastic antibiotic bleomycin has been examined in D2O solution (Fourier transform nuclear magnetic resonance, 270 MHZ) and in H2O solution (correlation nuclear magnetic resonance, 250 MHZ). Resonances have been assigned to specific hydrogens of the two most abundant congeners, bleomycin-A2 (BLM-A2) and bleomycin-B2 (BLM-B2), on the basis of (1) homonuclear spin decoupling, (2) comparison of the spectra of BLM-A2, BLM-B2, fragments of these antibiotics, and the related antibiotic phleomycin, and (3) the pH dependence of chemical shifts. Resonance assignments are presented for all the CH protons of BLM-A2 and BLM-B2 except for the saccharide groups, for which only the anomeric proton assignments are given. All of the NH protons have been identified with specific resonances except for the two primary amide groups, which yield four well-resolved peaks, whose specific assignment was not attempted. This study serves as a basis for future investigations of the conformation of bleomycin and its interaction with metals and nucleic acids.

Nuclear magnetic resonance spectroscopy. 13 C Fourier transform spectra of 8 - and 9 -tetrahydrocannabinol.

Carbon-13 nuclear magnetic resonance spectra have been taken of Delta(8)- and Delta(9)-tetrahydrocannabinol. The absorptions have been assigned to specific carbons with the aid of off-resonance and selective proton-decoupling experiments, as well as by chemical-shift comparison with model compounds.

Nuclear Magnetic Resonance Spectroscopy. Variable-Temperature C and F Study of the Chair-Chair Interconversion of 1,1,3,3-Tetramethylcyclohexane and gem-Difluoro-1,1,3,3-Tetramethylcyclohexanes.

A variable-temperature, proton noise-decoupled, (13)C nmr spectral study of the chair-chair interconversion in 1,1,3,3-tetramethylcyclohexane has demonstrated the utility of (13)C spectra for probing conformational equilibria. There is a much larger chemical-shift difference between the carbons of axial and equatorial methyl groups than between the protons of these methyl groups, 133 Hz compared to 7.5 Hz. Comparison of the activation parameters determined from the (13)C spectra of 1,1,3,3-tetramethylcyclohexane with those determined from a variable-temperature (19)F study on 2,2,6,6-tetramethyl-1,1-difluorocyclohexane shows that the introduction of a gem-difluoro group into the ring causes significant steric interactions. The (13)C chemical shifts for 1,1,3,3-tetramethylcyclohexane reflect the importance of the methyl-methyl 1,3-diaxial interactions.