Observation of radio-wave-induced red hydroxyl emission at low altitude in the ionosphere.

We report the discovery of radio-wave-induced red emission of OH Meinel rotation-vibrational bands at 629.79 nm. These are the first measurements of artificial aurora below 100 km. We believe that the 629.79-nm OH emission was due to radio-wave focusing by sporadic ionization clouds near 80-85 km altitude, thus giving a technique to visualize the low-altitude sporadic ionization and providing insight into ionospheric interactions at these low altitudes.

Barium enema: detection of colonic lesions in a community population.

OBJECTIVE: The purposes of this study were to assess the prevalence of colonic lesions detected at barium enema in a community practice, to compare the findings at barium enema between patients who are asymptomatic and have no known risk factors for colorectal cancer (screening group) and patients who have symptoms of colonic disease or have known risk factors, and to determine if a questionnaire about symptoms and risk factors is an appropriate screening tool. SUBJECTS AND METHODS: A self-administered questionnaire about colorectal symptoms and risk factors was given to 1779 patients scheduled for barium enema examination. On the basis of their responses, patients were divided into three groups: screening group (asymptomatic, without risk factors), symptomatic, and asymptomatic with risk factors. Each patient underwent a fluoroscopic barium enema. We then compared the results (number, histologic type, size of lesion(s), location in the colon, and Patient's age) and risk factors among the three groups. RESULTS: At least one lesion within the colorectum was found in 166 (9%) of 1779 patients at combined proctosigmoidoscopy and barium enema. The prevalence of lesions in the 111 patients with at least one lesion above the rectum at barium enema was 4% (32 of 738) for the screening group, 8% (38 of 476) for asymptomatic patients with risk factors, and 7% (41 of 565) for symptomatic patients (p = .015 when comparing the prevalence in the screening group with the prevalences in the other two groups). Twenty-nine percent of all colonic lesions were found in the screening group. Among the asymptomatic patients, risk factors that included a history of colorectal polyps and advanced age were associated with a significantly higher prevalence of colonic polyps found at barium enema. In the symptomatic group, if patients with histories of polyps were excluded, we were unable to identify other risk factors that led to a significantly higher prevalence of polyps. CONCLUSION: Asymptomatic patients without known risk factors have a significantly lower prevalence of colonic polyps than either symptomatic patients or patients with risk factors alone. Despite this lower prevalence, 29% of all lesions in our series were in the screening group. Assessment of risk factors through a patient questionnaire was not helpful in identifying a group of patients with a higher prevalence of lesions--except for a history of polyps. Management decisions based on a patient questionnaire should be approached with caution. When low-risk patients are denied screening examinations, a significant number of lesions will be missed.

Isolation of the human semaphorin III/F gene (SEMA3F) at chromosome 3p21, a region deleted in lung cancer.

Small cell lung cancer (SCLC) has been correlated with a deletion in the short arm of chromosome 3, with the region 3p21 being lost from one homolog in almost all cases. Two SCLC cell lines have homozygous deletions in 3p21, and these deletions overlap with a fragment of chromosome 3 that has tumor suppression activity in vivo. We have isolated some cDNA clones from this region that are homologous to the genes constituting the semaphorin family. They represent a novel human semaphorin, termed sema III/F (HGMW-approved symbol SEMA3F), which is expressed as a 3.8-kb transcript in a variety of cell lines and tissues; it is detected as early as Embryonic Day 10 in mouse development. There is high expression in mammary gland, kidney, fetal brain, and lung and lower expression in heart and liver. Although there is reduced expression of this gene in several SCLC lines, no mutations were found. This semaphorin homolog has characteristics of a secreted member of the semaphorin III family, with 52% identity with mouse semaphorin E and 49% identity with chicken collapsin/semaphorin D.

Exchange of precursor-specific elements between Pro-sigma E and Pro-sigma K of Bacillus subtilis.

sigma E and sigma K are sporulation-specific sigma factors of Bacillus subtilis that are synthesized as inactive proproteins. Pro-sigma E and pro-sigma K are activated by the removal of 27 and 20 amino acids, respectively, from their amino termini. To explore the properties of the precursor-specific sequences, we exchanged the coding elements for these domains in the sigma E and sigma K structural genes and determined the properties of the resulting chimeric proteins in B. subtilis. The pro-sigma E-sigma K chimera accumulated and was cleaved into active sigma K, while the pro-sigma K-sigma E fusion protein failed to accumulate and is likely unstable in B. subtilis. A fusion of the sigE "pro" sequence to an unrelated protein (bovine rhodanese) also formed a protein that was cleaved by the pro-sigma E processing apparatus. The data suggest that the sigma E pro sequence contains sufficient information for pro-sigma E processing as well as a unique quality needed for sigma E accumulation.

Mutational analysis of the precursor-specific region of Bacillus subtilis sigma E.

sigma E is a sporulation-specific sigma factor of Bacillus subtilis that is formed from an inactive precursor protein (pro-sigma E) by the removal of 27 to 29 amino acids from the pro-sigma E amino terminus. By using oligonucleotide-directed mutagenesis, sequential deletions were constructed in the precursor-specific region of sigE and analyzed for their effect on the gene product's activity, ability to accumulate, and susceptibility to conversion into mature sigma E. The results demonstrated that the first 17 residues of the pro sequence contribute to silencing the sigma-like activity of pro-sigma E and that the amino acids between positions 12 and 17 are also important for its conversion into sigma E. Deletions that remove 21 or more codons from sigE reduce sigma E activity in cells which carry it, presumably by affecting pro-sigma E stability. A 26-codon deletion results in a gene whose product is not detectable in B. subtilis by either reporter gene activity or Western blot (immunoblot) assay. The primary structure as well as the size of the pro region of sigma E contributes to the protein's stability. The placement of additional amino acids into the pro region reduces the cell's ability to accumulate pro-sigma E. Additional sigE mutations revealed that the amino acids normally found at the putative processing site(s) of pro-sigma E are not essential to the processing reaction; however, a Glu residue upstream of these sites (position 25) was found to be important for processing. These last results suggest that the pro-sigma E processing apparatus does not recognize the actual site within pro-sigma E at which cleavage occurs but rater sequence elements that are upstream of this site.

The sigma E subunit of Bacillus subtilis RNA polymerase is present in both forespore and mother cell compartments.

Bacillus subtilis cells harvested 3.5 h after the onset of sporulation (t3.5) were fractionated into extracts enriched in either mother cell or forespore components and were analyzed immunologically for sigma E and its precursor protein, P31. We determined by Western blot (immunoblot) analysis that equivalent amounts of P31 and sigma E were present in both mother cell and forespore extracts. This result implies that, although sigma E is not synthesized until a stage in development when the cell is partitioned into progenitor forespore and mother cell compartments, it probably directs the transcription of genes that are expressed in both of these structures.

Radiographic appearance of mucosal dysplasia associated with ulcerative colitis.

The radiographic appearance of dysplasia, a precancerous histologic change that is frequently present in colitic colons at high risk for cancer, was analyzed. Over a 5-year period, 170 patients with long-standing ulcerative colitis participated in a cancer surveillance program at our institution. On entry, all patients underwent radiography with a double-contrast barium enema and colonoscopy with multiple random biopsies. All radiographs were reviewed retrospectively and were correlated with the colonoscopic and histologic findings. Dysplasia, ranging from mild to severe, was found in the biopsy specimens from 26 (15%) of these patients (in 59 different regions). Thirteen of the 26 patients with dysplasia had colectomies, and the specimens were available for review. Most dysplasia is not radiographically visible, as was the case in 40 (68%) of the 59 regions found histologically to have dysplasia. In the 19 regions in which dysplasia was visible radiographically, it appeared as a solitary nodule or as several separate nodules in 11 (19%) of the 59 regions or as a close grouping of multiple adjacent nodules with apposed, flattened edges in 8 (14%) of the 59 regions. The radiographic finding of a nodule or of several separate nodules was not specific because these nodules were indistinguishable from the inflammatory nodules often present in colitic colons. On the other hand, the radiographic finding of a close grouping of adjacent nodules with apposed, flattened edges was associated with dysplasia 50% of the time. This radiographic appearance was seen in five of our 26 patients who had dysplasia. Our study shows that barium examinations are useful in some patients with chronic ulcerative colitis by suggesting the presence of dysplasia and directing the endoscopist to specific locations for biopsy.

Perspective: the small bowel examination in the diagnosis of Crohn's disease.

Enteroclysis has been increasingly recommended for radiologic examination of the small intestine, especially for focal lesions, but also for more extensive processes such as regional enteritis. Seventy-four patients were studied who had a final clinical diagnosis of regional enteritis and who had been examined by more conventional peroral ingestion of barium suspension together with fluoroscopy and vigorous manual compression. In only two cases did the radiographic examination fail to identify proven regional enteritis; one who had an isolated ulcer at an ileorectal anastomosis and one in whom jejunal regional enteritis was mistakenly diagnosed as a mesenteric mass. Careful fluoroscopy of the small intestine combined with vigorous manual compression is a sensitive method of detecting regional enteritis.

Is there a safe interval between diagnostic invasive procedure and the barium enema study of the colorectum?

In an attempt to define the optimal interval of safety when a barium enema study of the colon follows a planned injury of the bowel by local treatment or biopsy (or both), we studied a group of 833 patients who were seen at the Mayo Clinic during 1978. In the study group, 886 polyps were destroyed by fulguration, 258 lesions were both sampled and fulgurated, and 126 areas were sampled for biopsy study. One hundred ninety-four patients had multiple lesions; in 193 of these, 2-18 diminutive polyps were fulgurated. Of the 846 barium studies in the 833 patients, 5 were done on the same day as the planned injury, 543 within 24 hours, and 174 within 72 hours. Four patients demonstrated extravasation of barium, but none had signs or symptoms of acute perforation nor did the resected surgical specimen demonstrate communication with site of injury.

The fluoroscopic barium enema in colonic polyp detection.

The results of 1,500 barium enema studies done by vigorous manual palpation under fluoroscopy were reviewed to determine the adequacy of this technique in detecting polyps above the proctoscopic level. Of the 1,500 patients examined, 103 (7%) were diagnosed radiographically as having a total of 149 polyps. Polyps were found at proctoscopy in about 10% of the 1,500 patients. Colonoscopy or surgery was performed on 35 of the 103 patients. Of the 52 polyps discovered during these procedures, only three were missed at fluoroscopic barium enema study, a false-negative rate of 6%. Fourteen patients whose barium enemas initially were reported as negative for polyps or neoplasia had colonoscopy. Two of the 14 patients had positive findings, for a true-negative rate of 86%. If the detection rate of 7% found at barium enema, taking into account an overlap of 10%, is combined with the rate of 7.5% found at proctoscopy, a frequency of about 14% emerges in detecting polyps in the rectum and in the colon. Thus, the fluoroscopic barium enema when combined with proctoscopy is a sensitive method in the detection of colorectal polyps. In addition, it has the advantage of rapid execution and relatively low cost.

Barium enemas of carcinoma of the colon: sensitivity of double- and single-contrast studies.

A total of 1,140 primary colorectal carcinomas found in 1084 patients during a 5 1/2-year period (1976 to mid-1981) at the Mayo Clinic was reviewed to evaluate the accuracy of detection by the double- and single-contrast barium enema examinations. Both methods were equally sensitive in detecting colon cancer above the proctoscopic level. The error rate (ulcerative colitis excluded) was 4.8% for the single-contrast enema and 4.7% for the double-contrast study. Neither type of examination was superior in finding smaller lesions or earlier staged lesions. Several causes for error were identified: fluoroscopic inexperience, technical factors, misinterpretation of radiologic findings, and distraction.

Double-contrast radiography: colonic inflammatory disease.

Double-contrast examination and proctosigmoidoscopy were performed in 240 patients with ulcerative colitis and 60 patients with granulomatous colitis. Both examinations were evaluated for accuracy of detection of disease, accuracy of classification of disease, and the ability of one examination to add information not gained by the other. Endoscopy was more sensitive than double-contrast examination in detection of disease of the distal colon and rectum in 18% of cases of ulcerative colitis and 17% of cases of granulomatous colitis. Double-contrast examination was more specific than proctosigmoidoscopy in differentiation of disease in cases of ulcerative colitis; endoscopy incorrectly classified 11% of cases as granulomatous colitis, and double-contrast examination misclassified only one case (less than 1%). Neither examination misclassified a case of granulomatous colitis as ulcerative colitis. Finally, double-contrast examination demonstrated disease proximal to the range of the proctosigmoidoscope of a greater severity than that seen endoscopically in 24% of patients with ulcerative colitis and 70% of patients with granulomatous colitis. Radiographic variations in disease presentation occasionally caused difficulty in classification. Double-contrast examination and proctosigmoidoscopy are complementary, and both should be used in evaluating patients with inflammatory disease of the colon.