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Biomedical subjects

L Wilcox

Publications and source records attributed to L Wilcox.

At least 19 recordsLinked to original sources
PubMed2004

Genetically distinct populations of the dinoflagellate Peridinium limbatum in neighboring Northern Wisconsin lakes.

The extent to which free-living microorganisms exist in geographically isolated, genetically distinct populations is a subject of continuing debate. Some authorities contend that many microorganisms have cosmopolitan distributions, while others provide evidence that more limited geographical distribution of genetically distinct populations can occur. We report the occurrence of two morphologically similar, but genetically distinct, populations of the microbial eukaryote Peridinium limbatum (Stokes) Lemmermann from neighboring Northern Wisconsin freshwater bodies. Five strains of P. limbatum were cultured by single-cell isolation from both Crystal Lake and Crystal Bog (Oneida Co., WI). Genetic variation between the two populations encompassed 8.9% (mean of 35.4 of 397 nucleotides) of the nuclear ribosomal DNA internal transcribed spacer (ITS1 and ITS2) region. In contrast, 0.5% (mean of 2.25 of 397 nucleotides) variation was observed within the Crystal Lake population and 0.3% (mean of 1.21 of 397 nucleotides), within the Crystal Bog population. This difference between the two populations was highly statistically significant (p-value << 0.001). The extent of genetic variation between the two P. limbatum populations was greater than that reported in the literature for some morphologically distinguishable microalgal species, suggesting the occurrence of cryptic sister species. On the other hand, hybrid sequences obtained from one of the Crystal Lake strains suggest that the two populations may still be members of a single sexually compatible biological species. Our data suggest that the two neighboring P. limbatum populations may be diverging genetically under conditions of limited gene flow, suggesting a mechanism for the origin of geographically isolated, genetically distinct populations of microbial eukaryotes.

Animals↗
PubMed2003

Efficacy of a targeted, oral penicillin-based yaws control program among children living in rural South America.

Yaws is endemic in rural Guyana. An observational study was conducted to determine the efficacy of oral penicillin V therapy in treating skin lesions of yaws in children. In 1999, inhabitants of 7 rural villages near Bartica, Guyana, were screened for skin lesions of yaws. Cases were confirmed by serological testing. A control program was implemented in 2000: children < or =14 years old were screened, and those with active lesions were treated with oral penicillin V for 7-10 days. In 2001, children were rescreened and active cases were treated. Prevalence of yaws skin lesions fell from 5.1% (52 of 1020 children screened in 2000) to 1.6% (8 of 516 in 2001), a 71% drop. Sixteen (94%) of 17 children treated in 2000 and reassessed in 2001 had complete resolution of lesions. A targeted, oral penicillin-based treatment regimen can successfully treat dermatologic yaws in individual children and can decrease the prevalence of skin yaws in a community in which it is endemic. This information may aid in the implementation of additional control efforts.

Administration, Oral↗
PubMed1997

A randomized trial of surgical scrubbing with a brush compared to antiseptic soap alone.

BACKGROUND: The difference between use of a scrub brush versus soap alone in reducing hand bacterial counts has never been established by a prospective, comparative study. METHODS: Fifteen volunteers were taught the 5-minute surgical scrub. Baseline specimens were obtained by the glove fluid sampling procedure. Subjects were randomized to (1) scrub with an inert scrub brush and 4% chlorhexidine soap with isopropyl alcohol or (2) wash with 4% chlorhexidine soap with isopropyl alcohol alone. Specimens were obtained immediately after the scrub was completed and 45 minutes later. The experiment was repeated by use of a cross-over design after a 1-week washout period. The data were analyzed by three methods that took into account the broad range of baseline hand counts (5 x 10(1) to 11.2 x 10(4): method 1, the discordance between presence/absence of hand bacterial counts within individuals at 45 minutes for soap versus soap and brush; method 2, the absolute reduction of bacteria (baseline vs 45 min.) for soap versus soap and brush; and method 3, the proportional change in bacterial counts at 45 minutes from baseline for soap versus soap and brush. RESULTS: Although there was no statistically significant difference for any method, the point estimates for the odds ratio (OR) showed that up to twice the number of subjects had a greater reduction in bacterial counts when they washed with soap than when they scrubbed with a brush, as evidenced by the following data: method 1, OR 2.3 (95% confidence interval [CI] 0.53, 13.99) for soap alone; method 2, OR 1.0 (CI 0.23, 4.35); and method 3, OR 2.0 (CI 0.54, 9.10) for soap alone. CONCLUSIONS: The effect of use of soap alone in reducing hand bacterial counts at 45 minutes was similar to use of soap and brush. Soap can be used alone and the surgical infection rate prospectively monitored.

1-Propanol↗
PubMed1996

Misidentification of toxigenic Corynebacterium diphtheriae as a Corynebacterium species with low virulence in a child with endocarditis.

A 6-year-old boy presented to a university hospital in Malaysia with infective endocarditis complicating cyanotic congenital heart disease. Blood cultures showed a gram-positive, aerobic, coryneform-like bacillus identified by the hospital laboratory as Corynebacterium xerosis, but a reference laboratory identified the organism as a toxigenic strain of Corynebacterium diphtheriae. The two laboratories concurred on all biochemical test results except for sucrose fermentation.

Child↗
PubMed1995

Bacillus species pseudobacteremia following hospital construction.

A 13-fold increase (0.08 to 1.05%) in the isolation rate of Bacillus species from in-patient blood cultures led to the investigation of pseudobacteremia over a four-month period. Data on blood isolates (BACTEC NR 660, bottle types 6A and PEDS) of Bacillus species were compiled between July and October 1993. BACTEC bottles, as well as their plastic lids and rubber septa (representing 20% of stored bottles), and alcohol swabs, iodine preparation pads and butterfly collection systems were cultured. Air plates inside the BACTEC 660 instrument were cultured, as well as swabs of both the BACTEC needles and the interior of the BACTEC handling area. To investigate carry-over contamination, sterile BACTEC bottles were tested immediately following bottles containing Bacillus species. Growth of Bacillus species was obtained from 16% of the plastic lids and 1.3% of the rubber septa. No growth was obtained from other cultures. The outbreak coincide with construction on a driveway of the hospital over the area where BACTEC bottles were stored. Upon completion of construction in November 1993, the isolation of Bacillus species returned to baseline. No pseudobacteremia isolates occurred in areas where the trained intravenous team was assigned. In conclusion, hospital construction leading to airborne spread of Bacillus species may cause Bacillus species pseudobacteremia, and failure to disinfect blood culture bottles adequately may predispose to such an outcome.

Bacillaceae Infections↗
PubMed1994

Effectiveness of apical clearing: histological and radiographical evaluation.

Preparation of the apical one-third in curved canals is difficult both in debridement and maintaining canal shape. A technique of final apical preparation, "apical clearing," attempted to debride and increase the apical size without transportation. Apical clearing is defined as: following cleaning and shaping, sequentially rotating files two to four sizes larger than the initial (master) apical file at working length, then rotating the largest apical file again after a final irrigation and drying. This study evaluated histologically and radiographically the quality of apical preparation with or without apical clearing. Examined were (a) extent of transportation and (b) debris accumulation in the apical third. Fifty-four extracted teeth with vital pulps and curved canals were divided into two groups. After step-back preparation, 29 had apical clearing and 25 did not. Pre- and postpreparation double-exposed radiographs evaluated canal deviation. The apical one-third of the canals was examined histologically and ranked, based on remaining tissue, predentin, dentin shavings, other debris, and canal walls planed. Radiographically, the apically cleared group showed slight deviation of the canal during preparation. Histologically, canals in the apically cleared group had significantly less remaining tissue, predentin and debris, as well as more canal walls planed. This experiment showed that apically the apical clearing technique resulted in better debridement, with minimal increase in apical transportation.

Chi-Square Distribution↗
PubMed1994

Coronal leakage: bacterial penetration through obturated canals following post preparation.

Coronal leakage of bacteria from saliva into root canal filling materials is a potential cause of failure. This problem may be more pronounced when only a small volume of obturating material remains in the canal, such as after post preparation. In this study, coronal leakage of bacteria through unsealed, apically obturated canals was investigated using a new in vitro model system.

Dental Leakage↗
PubMed1989

Activation of the alternative pathway of complement by cellulosic hemodialysis membranes.

Compared to cellulose acetate, hemodialysis with cuprophan membranes is associated with greater activation of the alternative pathway of complement. Previous studies have shown that this difference is not due to a greater number of potential covalent binding sites for activated C3 on cuprophan. To investigate further the factors that influence complement activation by hemodialysis membranes, proteins were eluted from serum-treated cuprophan and cellulose acetate membranes with hydroxylamine at alkaline pH and analyzed by SDS-PAGE and Western blot. Approximately 23 times more total protein was removed from cellulose acetate. Virtually all the C3 in the cellulose acetate eluate was in the form of inactive fragments C3c and C3dg. In contrast, the functionally active form of C3 (C3b) was a prominent constituent of the cuprophan eluate. The binding of factor B (precursor of the catalytic subunit of the C3 convertase) and factor H (regulatory protein of C3 activation) to serum-treated membranes was also analyzed. By Scatchard's method, the affinity constant at equilibrium for factor B binding (KB) to the two types of membranes was not significantly different; however, there were approximately four times more factor B binding sites on the cuprophan than on the cellulose acetate. For cuprophan, the number of factor B binding sites was 1.6 times greater than the number of factor H binding sites. These studies demonstrate that a portion of the C3b molecules that bind to cuprophan are protected from degradation, and suggest that the complement activating capacity of hemodialysis membranes is determined by biochemical properties that modulate both the binding of serum proteins to the membrane and the interactions of the endogenous regulatory proteins with membrane-associated C3b.

Cellulose↗
PubMed1989

Effects of two types of cobra venom factor on porcine complement activation and pulmonary artery pressure.

Autologous porcine plasma that has been incubated with cuprophan haemodialysis membranes causes pulmonary hypertension and peripheral leucopenia following reinfusion into swine. These effects appear to be mediated by biologically active fragments of C3 and C5 that are generated as a consequence of ex vivo activation of complement. Putatively, C5a induces the leucopenia; however, the specific contributions of products of C3 and C5 activation to the pulmonary vasoconstriction have not been elucidated. In the present study, the effects of in vivo infusion of two different types of cobra venom factor (CVF) on peripheral leucocyte count and pulmonary artery pressure in the swine are reported. The CVF from Naja n. naja (CVF(TN)) was shown to activate both porcine C3 and C5, whereas the CVF from Naja h. haje (CVF(NH)) activated only C3. Both types of CVF produced pulmonary hypertension. Significant peripheral leucopenia, however, was observed only with CVF(TN). These results suggest that activation products of C3 contribute to the pulmonary hypertension but not to the peripheral leucopenia observed during haemodialysis using dialysis membranes that activate complement.

Animals↗
PubMed1988

Molecular and epidemiologic study of multiresistant Serratia marcescens infections in a spinal cord injury rehabilitation unit.

Between March 1984 and February 1986, ten patients admitted to a spinal cord injury/stroke rehabilitation unit became bacteriuric with a strain of Serratia marcescens resistant to ampicillin, cephalothin, cefoxitin, ticarcillin, cotrimoxazole, gentamicin, and tobramycin. All the patients were catheterized, and in most, bacteriuria was asymptomatic. The organism was also recovered from their hospital environment (sinks, toilets, urine-collecting basins). Analysis of total plasmid content of multiresistant isolates revealed the presence of two plasmids (7 kilobase, 25.5 kilobase), not found in aminoglycoside susceptible strains of Serratia marcescens. Restriction endonuclease analysis and Southern hybridization (DNA probe: 25.5 kilobase plasmid) verified that these plasmids were identical. The 25.5 kilobase plasmid was purified, introduced by transformation into an Escherichia coli strain C recipient, and was found to mediate resistance to gentamicin and tobramycin. The emergence of multiresistant Serratia marcescens coincided with an increase in antibiotic usage on the ward. The reservoir seemed to be the urinary tracts of asymptomatic catheterized patients and their contaminated hospital environment.

Adult↗
PubMed1987

Enteritis associated with Campylobacter laridis.

Campylobacter laridis has occasionally been isolated from patients with diarrhea, but its clinical significance in this setting has yet to be established. We report a patient with a self-limited diarrheal illness whose stool cultures yielded C. laridis. The patient also developed a specific serum bactericidal antibody response to this strain of C. laridis, suggesting that the organism was causally related to the enteric illness.

Adult↗
PubMed1982

Expanding gas bubbles for the repair of tears in the posterior pole.

Expanding, long-lived intraocular perfluorocarbon gas bubbles can make possible the repair of retinal detachments with holes or tears in the posterior pole. Vitrectomy is not necessary for injecting the gas. The patient should be prone in order to bring the gas bubble to the top of the visual axis. Four perfluorocarbon gases have the appropriate coefficient of expansion to provide adequate intraocular gas volumes by displacing the fluid vitreous. Volumes of 1 to 2 cc are sufficient. Intraocular space for these amounts can be obtained either by draining subretinal fluid or by injecting 0.6 cc of C2F6 (which expands 3.3x) without draining. If the patient cannot tolerate being prone, most of the fluid vitreous can be displaced with an intraocular injection of 0.9 cc of C4F10 (which expands 5x).

Fluorocarbons↗
PubMed1981

A comparison of bone loss from different skeletal sites during acute calcium deficiency in mice.

Severe Ca deficiency was produced by the combined stresses of a Ca-deficient diet and lactation in female mice. Alveolar bone loss was assessed by changes in alveolar crest height and in quantity of supporting trabecular bone. Changes in the femur were measured by changes in mineral content and in the cross-sectional area of the midshaft region, and in vertebrae by changes in mineral content. A similar decrease in bone was observed in all sites during progression of Ca deficiency with a similar increase during recovery. Maximum bone loss amounted to more than 50 per cent. Alveolar bone loss was characterized by a reduction in trabecular bone without loss of alveolar crest height.

Alveolar Process↗
PubMed1980

Diplopia in the aged: etiology and management.

A description of diplopia, its causes, compensating mechanisms, and therapy is presented. Diplopia may be of benign origin, e.g., presbyopia or convergence insufficiency, but in the elderly it can be a warning of a severe local disorder or systemic disease. Early medical diagnosis should be a prime objective. Most of these disorders, if identified in time, can be cured or at least relieved by appropriate medical and surgical treatment.

Aged↗