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Biomedical subjects

M L Wilson

Publications and source records attributed to M L Wilson.

At least 55 records · Page 3Linked to original sources
PubMed1997

Malignant transformation of mammalian cells initiated by constitutive expression of the polo-like kinase.

Polo-like kinase (Plk) is the mammalian homologue of the Drosophila polo and Saccharomyces cerevisiae CDC5 genes, which are thought to be involved in regulating chromosomal segregation. Previously, we showed that transient ectopic expression of Plk could induce DNA synthesis in quiescent NIH 3T3 cells, suggesting that Plk might also have a function during G1 or S phase. Here we report that microinjection of Plk mRNA is sufficient to drive quiescent cells into mitosis and that constitutive expression of Plk in NIH 3T3 cells causes oncogenic focus formation. These transformed cells grow in soft agar and form tumors in nude mice. Because Plk expression has been shown to be high in various human tumors, we suggest that Plk may contribute to the promotion and/or progression of human cancers.

3T3 Cells↗
PubMed1997

Comparison of BACTEC 12B vs solid media for the recovery of Mycobacterium avium complex from blood cultures in AIDS patients.

We compared liquid (BACTEC 12B) and solid culture media for the diagnosis of Mycobacterium avian complex (MAC) bacteremia among 258 AIDS patients with a positive blood culture. Neither culture media alone had adequate sensitivity; BACTEC 12B detected growth earlier. Use of both liquid and solid media may improve the yield of mycobacterial blood culture.

AIDS-Related Opportunistic Infections↗
PubMed1997

The early humoral response in human granulocytic ehrlichiosis.

The early antibody response in patients with human granulocytic ehrlichiosis (HGE) and in mice infected with the HGE agent was characterized by using sera to probe lysates of HL-60 cells infected with HGE organisms. Sera were obtained from 18 patients with HGE, mostly within the first 6 weeks of clinical infection, and from mice infected with the HGE agent for up to 3 weeks. A 44-kDa antigen was reactive with IgG in all 18 patients, and IgG to 40-, 65-, and 80-kDa antigens was present in 6, 8, and 7 patients, respectively. In addition, IgM to 40-, 44-, 65-, and 80-kDa antigens was found in 9, 5, 4, and 4 subjects. Immunoglobulins to antigens ranging between 95 and 125 kDa were detected less frequently. HGE agent-infected C3H/HeJ mice had an antibody response similar to that in humans. Thus, the 40- and 44-kDa proteins of the HGE agent elicit early strong antibody responses during infection. Characterization of the antigens recognized by antibodies during HGE should aid in diagnosis and understanding of the disease.

Animals↗
PubMed1997

Microhabitat-independent regional differences in survival of unfed Ixodes scapularis nymphs (Acari:Ixodidae) in Connecticut.

The effects of habitat and microclimate on survival of unfed nymphal black-legged ticks, Ixodes scapularis Say (approximately I. damnini Spielman, Clifford, Piesman & Corwin), were studied under natural conditions in southcentral and northwestern Connecticut. At both coastal and inland locations, survival of 3 groups of 20 wild-caught questing nymphs placed in nylon mesh bags was monitored in each of 3 different habitats (field, forest canopy, and forest/field edge) during summer 1995. Simultaneously, soil temperature, ground-level air temperature, and relative humidity were measured continuously within each habitat at both sites. The number of ticks surviving in each habitat was monitored weekly. Average daily survival rates of nymphs were related inversely to soil temperature but were not related to air temperature or humidity. Overall, nymphal ticks at the inland site survived significantly longer than those at the coastal site; however, no significant differences in mortality rates were found among habitats. These results suggest that inland environmental conditions are suitable for lengthy survival of unfed nymphal I. scapularis in regions where this tick is not yet abundant.

Animals↗
PubMed1997

Telomerase expression in normal endometrium, endometrial hyperplasia, and endometrial adenocarcinoma.

Telomerase activity has been detected in a broad range of human cancers and its expression could be an important step in tumor progression. Here, telomerase activity by the telomeric repeat amplification protocol in cases of benign endometrium, endometrial hyperplasia, and endometrial adenocarcinoma was tested. Telomerase expression was detected in 13 of 14 cases of proliferative phase endometrium, in 7 of 12 cases of secretory phase endometrium, but was not detected in any of 7 cases of atrophic endometrium. Three of three cases with evidence of luteal phase defect and one of four cases of chronic endometritis also expressed telomerase activity. Hyperplastic endometrium was positive for telomerase in 13 of 17 cases. Telomerase activity was detected in 40 of 48 cases of endometrial adenocarcinoma, which included 36 of 43 cases of endometrioid adenocarcinoma and four of five cases of papillary serous carcinoma. The detection of telomerase in endometrial adenocarcinoma was not associated with either architectural grade, myometrial invasion, or stage. There was statistically significant association, however, between telomerase activity in benign atrophic endometrium versus any endometrial abnormality in women 52 years of age or older.

Adenocarcinoma↗
PubMed1997

Update on detection of bacteremia and fungemia.

The presence of microorganisms in a patient's blood is a critical determinant of the severity of the patient's illness. Equally important, the laboratory isolation and identification of a microorganism present in blood determine the etiologic agent of infection, especially when the site of infection is localized and difficult to access. This review addresses the pathophysiology and clinical characteristics of bacteremia, fungemia, and sepsis; diagnostic strategies and critical factors in the detection of positive blood cultures; characteristics of manual and instrument approaches to bacteremia detection; approaches for isolating specific microorganisms associated with positive blood cultures; and rapid methods for the identification of microorganisms in blood cultures.

Bacteremia↗
PubMed1997

The diagnostic yield of acid-fast-bacillus smear-positive sputum specimens.

The yield of mycobacterial culture from acid-fast-bacillus smear-positive sputum specimens was 387 or 439 (88.2%). Forty-nine of 52 culture-negative specimens came from patients on treatment. We conclude that the yield of culture from smear-positive sputum specimens is very high and that only two acid-fast-bacillus smear-positive specimens are needed for the initial evaluation of pulmonary mycobacteriosis.

Bacterial Typing Techniques↗
PubMed1997

Propagation of granulocytic Ehrlichia spp. from human and equine sources in HL-60 cells induced to differentiate into functional granulocytes.

Ehrlichia spp. from human and equine sources in the northeastern Unites States were detected by PCR, isolated, and propagated in the HL-60 promyelocytic leukemia cell line. Growth of Ehrlichia from both equine and human sources was enhanced by addition of retinoic acid, which causes granulocytic differentiation of the HL-60 cells. DNA sequencing of a portion of the 16S rDNA gene supported the hypothesis that the same pathogen was responsible for both equine and human granulocytic ehrlichiosis.

Animals↗
PubMed1997

The incidence of false-positive cultures for Mycobacterium tuberculosis.

The frequency of false-positive cultures for Mycobacterium tuberculosis due to cross-contamination has been difficult to determine because of the lack of specific strain markers. Isolates collected prospectively over 5 yr from a municipal health department laboratory underwent DNA fingerprinting using the IS6110 and pTBN12 sequences. We reviewed the clinical and laboratory records of all isolates that had matching DNA fingerprints and were processed within 42 d of each other; 8 isolates were classified as probable or definite false-positives, representing 4.0% (8/199) of the culture-positive patients. A convenience sample of 42 isolates from three other mycobacterial laboratories also underwent DNA fingerprinting, and five (12%) were found to be definite or probable false-positives. Cross-contamination during initial processing of specimens was the most common source of false-positive cultures. The source of cross-contamination for three false-positive cultures was a laboratory proficiency survey specimen containing strain H37Ra. Ten of the 13 patients were misdiagnosed as having tuberculosis, and seven received unnecessary multidrug treatment. Clinicians should be aware of the potential for false-positive cultures for M. tuberculosis, and mycobacteriology laboratories need to carefully review procedures to minimize this occurrence. DNA fingerprinting provides a valuable tool for the study of false-positive cultures.

Bacteriological Techniques↗
PubMed1997

Emergence of raccoon rabies in Connecticut, 1991-1994: spatial and temporal characteristics of animal infection and human contact.

The North American raccoon rabies epizootic continues to expand, now affecting most of New England. In 1990, raccoons became the vertebrate most often reported rabid in the United States. Emergence of this zoonosis poses increasing, but poorly defined risks to humans. This study analyzed various demographic, environmental, and behavioral factors associated with animal infection and human exposure before and during the epizootic in Connecticut. Rabies virus infections among terrestrial vertebrates were analyzed from 1985 through 1994. From March 1991, when the first case was diagnosed, through December 1994, 2,522 of 13,147 animals tested were found positive for rabies viral antigen. Forty-seven percent of the raccoons tested were infected, representing 88.0% of all animals found positive. Domestic animals constituted only 1.7% of positive test results, but 40.6% of the tests performed. The epizootic wave of transmission advanced approximately 30 km/year. Most rabies-positive wild animals were taken from private properties, usually near houses. Possible human exposures involved 939 people on 556 occasions through direct contact (20.7%) or indirectly through another animal (79.3%). Of 3,239 domestic animals exposed to rabies-positive wild animals, 18.4% lacked vaccination. Rabies has become enzootic in Connecticut and risk to humans and animals persists. The public health burden is considerable, yet knowledge is lacking to develop sustainable prevention strategies.

Animals↗
PubMed1996

Interaction of cyclooxygenases with an apoptosis- and autoimmunity-associated protein.

Cyclooxygenases (COXs) 1 and 2 are 72-kDa, intralumenal residents of the endoplasmic reticulum (ER) and nuclear envelope, where they catalyze the rate-limiting steps in the conversion of arachidonate to the physiologically dynamic prostanoids. Recent studies, including the generation of knockout mice, show COX-1 and COX-2 to have biologically distinct roles within cells and organisms. Also apparent is that arachidonate substrate is selectably metabolized by COX-2 after mitogen stimulation in many cells that contain both isoforms. Because COX-1 and COX-2 are highly conserved in all residues needed for catalysis and in their purified forms have almost identical kinetic properties, we have searched for COX-interacting ER proteins that might mediate these unique isoenzymic properties. Using COXs as bait in the yeast two-hybrid system, we identified autoimmunity- and apoptosis-associated nucleobindin (Nuc) as a protein that specifically interacts with both isoenzymes. COX-Nuc binding was substantiated by immunoprecipitation experiments, which showed that COX-1 and, to a lesser extent, COX-2 form complexes with Nuc in vitro. When overexpressed in COS-1 cells, Nuc was found to be extracellularly released. However, when Nuc was co-overexpressed with COX-1 or COX-2, its release was reduced by >80%. This finding suggests that COX isoenzymes participate in the retention of Nuc within the lumen of the ER, where COX may regulate the release of Nuc from the cell. It also identifies Nuc as a potential regulator of COXs through this interaction.

Animals↗
PubMed1996

Prolonged incubation of blood and bone marrow cultures in 12B bottles processed on the BACTEC 460 TB system does not increase microbial recovery.

Standard references continue to recommend testing specimens processed on the BACTEC TB System for 8 weeks, despite evidence that mycobacteria are rarely recovered beyond 5-6 weeks. To clarify this issue, we retrospectively reviewed all positive blood/bone marrow cultures processed during a 17-month period when specimens were tested for 6 weeks. We then prolonged the incubation period to 8 weeks during the subsequent 5 months. Excluding Mycobacterium genavense, only 1 of 159 mycobacterial isolates was recovered during and none were recovered beyond the 5th week of incubation and testing on the BACTEC TB System.

Bacteriological Techniques↗
PubMed1996

General principles of specimen collection and transport.

In this issue of Clinical Infectious Diseases, we present the first article in a series entitled "Diagnostic Microbiology Updates." Although clinical microbiology is included in the curricula of virtually all infectious disease fellowships, the degree of emphasis on this subject varies considerably. Infectious disease physicians--even those who have direct responsibilities or consulting responsibilities for the microbiology laboratories of the institutions in which they practice--may be hard pressed to keep up with the rapidly changing content of the primary literature in clinical microbiology. The purpose of this series, therefore, is at least in part to fill this void and to provide concise updates for clinicians. The first article, written by Dr. Michael L. Wilson, reviews current concepts in specimen collection and transport. A key issue for all clinicians (which is not always sufficiently emphasized) is the quality of the specimen submitted to the laboratory. It is an axiom that if specimens of poor quality are submitted, the results generated by the laboratory will have little or no clinical utility. Dr. Wilson's article describes some of the methods available to assure that only specimens of good quality, i.e., those most likely to be useful clinically, are processed in the microbiology laboratory. Future articles will address specific types of specimens, groups of pathogens, and diagnostic techniques, including molecular methods. We hope this series will be informative and valuable to the readers of Clinical Infectious Diseases, and we look forward to your comments.

Blood↗
PubMed1996

Microclimate-dependent survival of unfed adult Ixodes scapularis (Acari:Ixodidae) in nature: life cycle and study design implications.

Microclimate and other abiotic factors may be important in determining the survival of arthropod vectors, yet the impact of such variables rarely has received careful examination. The impacts of habitat, microclimate, and experimental confinement on survival rates of unfed adult blacklegged ticks, Ixodes scapularis Say, were studied in field enclosures in southcentral and northwestern Connecticut. At both locations, 2 enclosures were placed in each of 3 different habitats (field, forest canopy, and forest/field edge). Forty wild-caught adult ticks (20 males, 20 females) were placed in each enclosure. At one site, another 40 ticks were confined to nylon mesh bags placed inside each enclosure. Soil temperature, ground-level air temperature and relative humidity were measured within each habitat. The number of ticks surviving within each enclosure was monitored 1 or 2 times per week. Ticks that were confined in nylon bags had a lower survival rate than ticks that were able to move freely within the enclosures. Ticks survived longer in edge and forest habitats than in open fields, which were characterized by greater extremes in air temperature, soil temperature, relative humidity, and vapor pressure deficit than the other 2 habitats. The mean daily survival rates of free-ranging I. scapularis were negatively related to air temperature, vapor pressure deficit, and the coefficient of variation of relative humidity.

Animals↗