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L McDaniel

Publications and source records attributed to L McDaniel.

At least 19 recordsLinked to original sources
PubMed2005

Effect of nutrient addition and environmental factors on prophage induction in natural populations of marine synechococcus species.

A series of experiments were conducted with samples collected in both Tampa Bay and the Gulf of Mexico to assess the impact of nutrient addition on cyanophage induction in natural populations of Synechococcus sp. The samples were virus reduced to decrease the background level of cyanophage and then either left untreated or amended with nitrate, ammonium, urea, or phosphate. Replicate samples were treated with mitomycin C to stimulate cyanophage induction. In five of the nine total experiments performed, cyanophage induction was present in the non-nutrient-amended control samples. Stimulation of cyanophage induction in response to nutrient addition (phosphate) occurred in only one Tampa Bay sample. Nutrient additions caused a decrease in lytic (or control) phage production in three of three offshore stations, in one of three estuarine experiments, and in a lysogenic marine Synechococcus in culture. These results suggest that the process of cyanophage induction as an assay of Synechococcus lysogeny was not inorganically nutrient limited, at least in the samples examined. More importantly, it was observed that the level of cyanophage induction (cyanophage milliliter(-1)) was inversely correlated to Synechococcus and cyanophage abundance. Thus, the intensity of the prophage induction response is defined by ambient population size and cyanophage abundance. This corroborates prior observations that lysogeny in Synechococcus is favored during times of low host abundance.

Bacteriophages↗
PubMed2003

A protein interaction map of Drosophila melanogaster.

Drosophila melanogaster is a proven model system for many aspects of human biology. Here we present a two-hybrid-based protein-interaction map of the fly proteome. A total of 10,623 predicted transcripts were isolated and screened against standard and normalized complementary DNA libraries to produce a draft map of 7048 proteins and 20,405 interactions. A computational method of rating two-hybrid interaction confidence was developed to refine this draft map to a higher confidence map of 4679 proteins and 4780 interactions. Statistical modeling of the network showed two levels of organization: a short-range organization, presumably corresponding to multiprotein complexes, and a more global organization, presumably corresponding to intercomplex connections. The network recapitulated known pathways, extended pathways, and uncovered previously unknown pathway components. This map serves as a starting point for a systems biology modeling of multicellular organisms, including humans.

Animals↗
PubMed2002

Lysogeny in marine Synechococcus.

Viral infection of bacteria can be lytic, causing destruction of the host cell, or lysogenic, in which the viral genome is instead stably maintained as a prophage within its host. Here we show that lysogeny occurs in natural populations of an autotrophic picoplankton (Synechococcus) and that there is a seasonal pattern to this interaction. Because lysogeny confers immunity to infection by related viruses, this process may account for the resistance to viral infection seen in common forms of autotrophic picoplankton.

Bacteriophages↗
PubMed2002

Seasonal variation in lysogeny as depicted by prophage induction in Tampa Bay, Florida.

A seasonal study of the distribution of lysogenic bacteria in Tampa Bay, Florida, was conducted over a 13-month period. Biweekly water samples were collected and either were left unaltered or had the viral population reduced by filtration (pore size, 0.2 micro m) and resuspension in filtered (pore size, 0.2 micro m) water. Virus-reduced and unaltered samples were then treated by adding mitomycin C (0.5 micro g ml(-1)) to induce prophage or were left untreated. In order to test the hypothesis that prophage induction was phosphate limited, additional induction experiments were performed in the presence and absence of phosphate. Induction was assessed as an increase in viral direct counts, relative to those obtained in controls, as detected by epifluorescence microscopy. Induction of prophage was observed in 5 of 25 (20%) unaltered samples which were obtained during or after the month of February, paralleling the results from a previous seasonal study. Induction of prophage was observed in 9 of 25 (36%) of the virus-reduced samples, primarily those obtained in the winter months, which was not observed in a prior seasonal study (P. K. Cochran and J. H. Paul, Appl. Environ. Microbiol. 64:2308-2312, 1998). Induction was noted in the months of lowest bacterial and primary production, suggesting that lysogeny was favored under conditions of poor host growth. Phosphate addition enabled prophage induction in two of nine (22%) experiments. These results indicate that prophage induction may occasionally be phosphate limited or respond to increases in phosphate concentration, suggesting that phosphate concentration may modulate the lysogenic response of natural populations.

Bacteria↗
PubMed2001

Evaluation of marine bacterial lysogens for development of a marine prophage induction assay.

The demonstrated relationship between carcinogenicity of a chemical compound in mammals and its tendency to cause prophage induction in bacteria provides a method for biologically based carcinogen screening. Because of the need for this type of screening and the abundance of lysogens in the marine environment, 14 isolates were evaluated for the degree of prophage induction in exponentially growing cultures in the presence of a known mutagen (0.5 microg/ml mitomycin C). Assays were performed both in liquid culture and in microtiter plates. Virus-like particles were enumerated by epifluorescence microscopy after staining with SYBR-Gold. Two isolates designated P94-4B3 (identified as Halomonas aquamarina) and P94-4S3 (identified as Pseudomonas aeruginosa) were further evaluated for potential use. Because of the rapid growth, larger size of its virus-like particles, and linear response to increasing dose of mitomycin C, the P. aeruginosa st. P94-4S3 was determined a better candidate for the marine prophage induction assay (MPIA). The Pseudomonas isolate was then used in several experiments for the development and optimization of the MPIA procedure. Initial screenings of the MPIA were also performed with selected environmental pollutants.

Journal Article↗
PubMed1996

Congenital digital deformities.

Congenital digital deformities are often challenging to treat. Several deformities and their treatments are discussed. Familiarity with the deformities is important because early treatment is often necessary for a successful outcome.

Child↗
PubMed1987

Patient management after endoscopic removal of the cancerous colon adenoma.

The subject of management of patients after endoscopic removal of cancerous adenomas is controversial. A retrospective review of 126 lesions in 121 patients who had had colonoscopic polypectomy of malignant lesions between 1971 and 1985 was used to determine the criteria for colon resection. Invasive cancer was identified in 80 patients, while 41 patients had carcinoma in situ. A synchronous colon cancer was found in five of the 121 patients. The patients who had carcinoma in situ had no evidence of residual tumor or metastatic disease on subsequent follow-up (colon resection in three patients and endoscopic surveillance in 38 patients). Of the 80 patients with invasive cancer, 44 had subsequent colon resection, and 34 of these had no evidence of tumor in the resected bowel or mesenteric lymph nodes. Ten patients had residual tumor, metastatic cancer to regional lymph nodes, or both. Each of the 10 had at least one of the following indications of inadequate resection or dissemination of disease to local lymph nodes (the first indication is a macroscopic evaluation, while the remaining four are all microscopic): incomplete excision, poorly differentiated tumor, invasion of the line of resection, invasion of the polyp stalk, and invasion of venous or lymphatic channels. Present recommendations for patient management after endoscopic removal of an invasive malignant adenoma should include colon resection with regional lymphadenectomy for patients with one or more of these five criteria. Patients without any of these risk factors should have early repeat endoscopic examination 3 months after initial polypectomy to evaluate the polypectomy site. Total colonoscopic examination is repeated at 1 year to ensure the surveillance program is begun with a colon without neoplasms.

Adenoma↗
PubMed1985

Experience with 1000 colonoscopic polypectomies.

Experience with 1000 consecutive polypectomies in 591 patients, from December 1975 to October 1982, is reviewed. There were 633 adenomas, 292 hyperplastic, and 75 miscellaneous polyps. While eight minor bleeding episodes (0.8%) occurred, there were no major complications (perforations or bleeding requiring transfusion). The polyp retrieval rate was 97.9%. Of the 633 adenomas, seven (1.1%) had in situ carcinoma and ten (1.6%) invasive. Eight of the invasive group underwent colon resection with no positive nodes present. Anatomic location demonstrated a shift to the right side of the colon. Three hundred thirty-six (53.1%) were in the rectosigmoid; 134 (21.3%) were in the left colon; 79 (12.3%) were in the transverse colon; and 84 (13.3%) were in the right colon and cecum. Patients who have undergone benign polypectomy are colonoscoped again in 1 year, and, if negative, every 3 years thereafter. Postpolypectomy patients with malignant adenomas require closer observation. Endoscopic polypectomy, with its lower morbidity and mortality, has revolutionized the treatment of the colon polyp. It is also more cost-effective, with outpatient polypectomy being 29 times less expensive and inpatient polypectomy four times less expensive than transabdominal polypectomy.

Adenoma↗
PubMed1984

Foreign bodies of the upper gastrointestinal tract: current management.

The popularity of the flexible esophagogastroduodenoscope prompted us to reevaluate our management of foreign bodies. In this paper we report our experience and update treatment guidelines. In our series (from December 1975 to May 1982), 74 foreign bodies were removed: 12 with the rigid endoscope, 60 with the flexible endoscope, and two surgically. There was no morbidity or mortality. In the age group 1 to 10 years, there were 15 patients, while the age group 11 to 88 years had 59 patients. Although the rigid endoscope is less expensive and has a larger operating channel, the advantages of the flexible instrument are numerous. Foreign bodies of the pharynx and at the level of the cricopharyngeus muscle are best managed with a rigid endoscope; foreign bodies of the esophagus can be managed with rigid or flexible instruments, but are more easily managed with the latter. Foreign bodies of the stomach and duodenum that require removal can be managed only with the flexible panendoscope.

Adolescent↗
PubMed1984

The use of endoscopy in assessment and treatment peptic strictures of the esophagus.

In the 1960s, evaluation of peptic strictures of the esophagus was a significant and difficult clinical problem. The use of rigid esophagoscopes and general anesthesia resulted in high complication rates. Most peptic esophageal strictures were managed surgically. The 1970s brought a dramatic change in the management of peptic strictures of the esophagus. With the introduction and widespread use of the forward-viewing, flexible panendoscope for upper gastrointestinal (GI) endoscopy, general anesthesia is no longer needed; evaluation of the peptic stricture has become one of the most common procedures in GI endoscopy. From December 1975 to October 1982, 1000 dilations were performed with a morbidity of 0.2 per cent and a mortality of 0.1 per cent. Initially, radiographic evaluation proximal to, distal to, and at the stricture is conducted. Endoscopic evaluation of the same three areas is then performed with emphasis on determining whether the stricture is benign or malignant. Malignancy can be determined visually in more than 90 per cent of the patients and in more than 95 per cent of the patients with multiple biopsies and cytology. Immediate dilation, using rubber (Maloney) dilators (Pilling Medical Co., Fort Washington, PA) or Eder-Puestow dilators (Eder Instrument Co., Chicago, IL), is then performed. The personality of the stricture determines which dilator can be used with greatest safety.

Biopsy↗
PubMed1984

Endoscopic evaluation of dysphagia in two hundred and ninety-three patients with benign disease.

A total of 538 dilations were performed upon 293 patients evaluated at our unit. Of these, 4.8 per cent had cervical webs, 3.0 per cent had cricopharyngeal dysfunction, 9.2 per cent had undetermined cause, 3.4 per cent had achalasia, 65.5 per cent had peptic strictures, 3.8 per cent had Schatzki's ring, 2.4 per cent had esophagitis, 6.1 per cent had postoperative strictures, 0.3 per cent had caustic stricture and 1.4 per cent had extrinsic compression. True dysphagia should always be investigated through a careful history, physical examination, barium study, endoscopy and, infrequently, esophageal manometry.

Adolescent↗
PubMed1981

Endoscopic evaluation of 125 cases of upper gastrointestinal bleeding.

The fiberoptic panendoscope has been shown to be superior to the UGI series in diagnosing the site(s) of upper gastrointestinal bleeding (UGIB). Recent data has shown that gastritis has replaced peptic ulcer disease (PUD) as the leading cause of UGIB since the diagnosis can now be made with the endoscope. Our clinical experience differs from this. One hundred twenty five cases of UGIB from December 1975 to December 1978 were reviewed. The patients ranged in age from 11 to 91 years. There were 83 males and 42 females included in the study. Twenty-four per cent of the patients were actively bleeding at the time of endoscopic examination, and 62% received two or more units of blood. Endoscopic examination was technically successful in all patients, and there were no deaths or complications. One hundred twenty three lesions were found in 117 patients for a diagnostic accuracy of 93.9%. In eight patients, no bleeding site was found, resulting in a failure rate of 6.1%. PUD accounted for 74.9% of the bleeding sites, while gastritis accounted for only 0.8%. Mallory-Weiss tears of the esophagus accounted for 9.8% and esophageal varices for 4.9%. Thirty-five per cent of the patients had associated lesions, with gastritis and esophagitis being the most common. Eighteen patients (14.4%) required surgical intervention. Seventeen patients had PUD. There was one death, for a mortality rate of 5.5%. The medical mortality rate was 0.9%. The benefits of endoscopy in UGIB are still controversial. An important subgroup of patients with the "visible vessel" in the ulcer bed has been identified recently by others. If not bleeding at the time of endoscopy, 70% will rebleed. It is our opinion that it is important to identify this patient, as well as to know if one is treating gastritis, PUD, or varices. Finally, electrocoagulation of bleeding points, as well as the development of the laser and application of adhesives or clotting agents through the endoscope, will change the management of UGIB.

Adolescent↗