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Biomedical subjects

H C Carlson

Publications and source records attributed to H C Carlson.

At least 19 recordsLinked to original sources
PubMed1992

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.

Amino Acid Sequence↗
PubMed1989

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.

Bacillus subtilis↗
PubMed1987

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.

Colitis, Ulcerative↗
PubMed1986

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.

Adolescent↗
PubMed1979

Pathological studies of "Sudden death syndrome" in broiler chickens.

Sudden death syndrome usually occurs in heavy, fast-growing and healthy-looking broilers. Most of the affected birds are males. The characteristic necropsy changes are seen in well-fleshed broilers with edema and generalized pulmonary congestion, recently ingested feed in the crop and gizzard, distended intestine with creamy content and empty gall bladder. The liver and kidneys are slightly enlarged and the latter have patchy areas of subcapsular hemorrhage. The heart contains clotted blood in the atria but the ventricles are often empty and the left ventricle in particular assumes a hypertrophied appearance. Microscopic examination of heart muscle reveals degeneration of fibers, separation of cardiac muscle fibers by edema and infiltration of heterophils. The lungs have severe vascular congestion, inflammatory cell infiltration in the mucosa of the secondary bronchi and edema fluid in the tertiary bronchi and interlobular connective tissue. The liver has moderate bile duct hyperplasia, periportal hepatitis and mononuclear cell infiltration adjacent to bile ducts which possibly leads to bile duct constriction. The kidneys have subcapsular and parenchymatous hemorrhage.

Animals↗
PubMed1979

Studies on effect of lighting on "Sudden death syndrome" in broiler chickens.

Broiler chicken flocks were studied to determine the mortality from sudden death syndrome occurring in the flocks. The difference in the incidence of the syndrome in pullets and cockerels, and the age at which the most birds are affected were also studied. The weight of sudden death syndrome birds was compared with the flock average and the effect of continuous lighting as opposed to intermittent lighting was examined. The results suggest that; continuous lighting produces more sudden death syndrome deaths than intermittent lighting; that the incidence of sudden death syndrome is higher in cockerels than pullets; that the highest death rate occurred during the third and fourth weeks of life, and that sudden death syndrome birds on the average were heavier than the flock average.

Animals↗
PubMed1978

Chronic ulcerative colitis and colon cancer: can radiographic appearance predict survival patterns?

Twenty-four patients with chronic ulcerative colitis and colon carcinoma who underwent barium enema examination prior to the diagnosis of cancer were studied in an attempt to correlate the radiographic appearance of the tumors with their biologic behavior, as well as to assess the accuracy of the barium enema in detection. Of the radiographically detected tumors, 65% displayed an annular infiltrative appearance, with the prime radiographic manifestation being relative nondistensibility of the involved segment. The remaining tumors had various appearances more typical of noncolitic colon cancer. Patients with infiltrative lesions had a much poorer prognosis than those with noninfiltrative lesions. Of 33 gross tumors described pathologically and/or surgically, only 70% were correctly detected by barium enema. It is suggested that periodic barium enema examinations are an unreliable means of following patients with ulcerative colitis if malignant degeneration is to be detected at an early and curative stage. Prophylactic proctocolectomy may be the best therapeutic approach.

Adult↗
PubMed1978

Salmonella investigation in an Ontario feed mill.

The frequency of Salmonella contamination of feedstuffs and finished broiler chicken feeds at an Ontario feed mill were investigated over a four-month period. Samples of feed ingredients and finished pelleted feeds were collected at various points during manufacture and cultured in trypticase soy broth prior to selective enrichment for isolation of Salmonella. Salmonella contamination was found in 4.3% of 93 finished pelleted broiler feeds examined. The contamination appeared to result primarily from the incorporation of contaminated animal protein ingredients into the feed. Meatmeal and the broiler, premix, which contained meatmeal as a filler, were most frequently contaminated followed by feather meal. Pelleting failed to eliminate the Salmonellae from the feeds. The methods used failed to detect Salmonella in the environment of the feed mill or its delivery trucks. Recommendations for control are made.

Animal Feed↗
PubMed1978

Sources of Salmonellae in broiler chickens in Ontario.

Sources of Salmonellae infecting broiler chicken flocks in Ontario were investigated from July, 1975 to April, 1976. Three broiler flocks were investigated on each of four farms which received chicks from a common hatchery. Samples of feed and new litter were preenriched in nonselective broth subcultured to Salmonella-selective enrichment broth and plated on Salmonella-selective differential agar. Samples of used litter, water, culled chicks, insects, mice, wild birds and environmental swabs were not cultured initially in the nonselective broth. Fecal samples from principal and occasional flock attendants were examined for Samonellae. Salmonella infection, as judged by contaminated flock litter was detected in six flocks on two of the farms while the flocks on the other farms remained negative. Salmonellae were isolated from 23 of 412 feed samples (nine serotypes), six of 35 new wood shaving samples (four serotypes), one of 29 pools of culled chick viscera (one serotype) and 44 of 267 used litter samples (14 serotypes). These results indicate that broiler chicken flocks were infected with diverse Salmonellae introduced in day old chicks, pelleted feeds, wood shavings and residual contamination from the preceding flock.

Animal Feed↗
PubMed1977

Secondary neoplasms of the small bowel.

Patterns of small bowel involvement from primary neoplasms elsewhere in the body were studied in order to determine whether the location of the lesions or their radiological appearance could provide criteria for distinguishing secondary from primary lesions. Multiplicity of lesions and the finding of "transverse stretch" were found to be highly indicative of secondary neoplastic involvement of the small bowel.

Humans↗
PubMed1977

The effect of an alexidine mouthwash on dental plaque and gingivitis.

The alexidine mouthrinse used in this study (CP-101) is effective in reducing plaque. There was a reduction in gingivitis after 6-months use but not at a statistically significant level. An extrinsic brown stain occurred at a significant level on the teeth of participants using the active mouthrinse. Blood and urine laboratory results indicated that alexidine can be safely used over a 6-month period.

Adolescent↗
PubMed1977

Antimicrobial susceptibility of Salmonella isolates from the broiler chicken industry in Ontario.

Antibacterial drug resistance among 219 salmonella isolates recovered during 1974 from poultry and poultry environments at the various production stages of broiler chickens in three integrated Ontario companies are recorded. All isolates were susceptible to ampicillin, trimethroprim-sulfamethoxazole complex, furazolidone, cephaloridine and amoxicillin. A relative increase in resistance to tetracycline and streptomycin with an accompanying decrease in resistance to triple sulfa compound was recorded when compared to a previous investigation of avian salmonella isolates in Ontario. The percentage and patterns of antimicrobial resistance were comparable at the various stages of production. Resistance to tetracycline and streptomycin was the most common pattern found among both Salmonella typhimurium and other serotypes. A notably high prevalence of resistance was found among Salmonella enteritidis isolates including some isolates with R factors for chloramphenicol resistance. This latter finding is of particular concern because of the high prevalence of this serotype in poultry and in human salmonellosis.

Animals↗