Biomedical subjects
P Carlson
Publications and source records attributed to P Carlson.
Neonatal Candida parapsilosis outbreak with a high case fatality rate.
A Candida parapsilosis outbreak of 58 cases in a neonatal intensive care unit lasted for 55 months. Patients infected by or colonized with C. parapsilosis were mainly very low birth weight infants (birth weight < 1500 g). Their mean birth weight was 817 g and their mean gestational age was 28 weeks. Statistical analysis including logistic regression confirmed that prematurity was the main risk factor. The analysis also suggested that C. parapsilosis infection (or colonization) was associated with a poor prognosis. In infants with gestational age < 29 weeks the risk for death in C. parapsilosis-infected patients was 16-fold greater than in those with no C. parapsilosis infection. The case fatality rate of C. parapsilosis patients was higher than that of the controls (9 of 23 vs. 1 of 40; P < 0.0001). The outbreak was most likely a result of cross-infection because C. parapsilosis could be isolated only from the patients and from the hands of four nurses immediately after they had cared for a colonized patient. Cessation of the outbreak was temporally associated with long term parenteral fluconazole (6 mg/kg/day) prophylaxis.
Arcanobacterium haemolyticum and streptococcal pharyngitis in army conscripts.
Arcanobacterium haemolyticum was found in 1.4% and beta-haemolytic streptococci in 23% of throat cultures from army conscripts with sore throat (n = 498). 38% of the beta-haemolytic streptococci were of group A. Patients culture-positive for A. haemolyticum or beta-haemolytic streptococci had pharyngeal exudate, cervical lymphadenopathy and ear ache significantly more often--but cough less often--than culture-negative patients. The pharyngeal colonization rate of healthy conscripts (n = 232) by A. haemolyticum was 0.4% and by beta-haemolytic streptococci, 6.5%.
The big picture: scheduling for a competitive advantage.
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Evaluation of a commercial kit in the identification of Arcanobacterium haemolyticum and Actinomyces pyogenes.
Listeria-Zym is a commercial kit designed to identify Listeria spp. within 4 h. Its ability to identify two clinically important aerobic catalase-negative, gram-positive rods, Arcanobacterium haemolyticum and Actinomyces pyogenes, was evaluated. Xylose fermentation and alpha-mannosidase tests differentiated Arcanobacterium haemolyticum (n = 49) from Actinomyces pyogenes (n = 24) strains.
Antimicrobial susceptibility of Arcanobacterium haemolyticum.
The susceptibilities of 138 clinical isolates of Arcanobacterium haemolyticum to 11 antimicrobial agents were tested. All strains were susceptible to phenoxymethylpenicillin, cephalosporins, erythromycin, azithromycin, clindamycin, vancomycin, doxycycline, and ciprofloxacin but were resistant to trimethoprim-sulfamethoxazole.
Alpha-mannosidase: a rapid test for identification of Arcanobacterium haemolyticum.
A 4-h alpha-mannosidase test for identification of Arcanobacterium haemolyticum strains (n = 139) and differentiation of A. haemolyticum from Actinomyces pyogenes strains (n = 30) and other gram-positive rods was evaluated. Practically all A. haemolyticum strains (138 of 139) and the Listeria monocytogenes type strain were alpha-mannosidase positive, while all A. pyogenes strains and Corynebacterium (n = .25) strains as well as the Rhodococcus equi and Erysipelothrix rhusiopathiae type strains were negative. The rapid alpha-mannosidase test, in conjunction with a Gram stain and catalase and reverse CAMP tests, was useful in identification of A. haemolyticum and in differentiation of A. haemolyticum from A. pyogenes and Corynebacterium spp.
Biotypes of Arcanobacterium haemolyticum.
Colony morphology, beta hemolysis on horse blood agar, beta-glucuronidase activity, and ability to ferment sucrose and/or trehalose defined two biotypes of Arcanobacterium haemolyticum. One, the smooth type, grew as smooth, beta-hemolytic colonies and was beta-glucuronidase negative but often fermented sucrose and/or trehalose, while the other, the rough type, grew as rough colonies and was nonhemolytic, beta-glucuronidase positive, and negative for sucrose and trehalose fermentation. About 75% of the A. haemolyticum strains studied (n = 138) were of the smooth type. The smooth type predominated in wound infections, while the rough type was isolated almost exclusively from respiratory tract specimens; thus, 84% of the smooth-type strains were derived from wounds and 91% of the rough-type strains were isolated from respiratory tracts.
Arcanobacterium haemolyticum and streptococcal pharyngitis.
Arcanobacterium haemolyticum was recovered from 0.5% of throat cultures of 3,922 patients seeking medical attention because of sore throat. Most of the patients positive for A. haemolyticum were 15-25 years old, and had fever (80%), lymphadenopathy (67%), pharyngeal exudate (69%) or skin rash (23%). In this age group, 2% of the throat cultures proved positive for A. haemolyticum. All A. haemolyticum strains were susceptible to penicillin, erythromycin, cephalexin and clindamycin, but resistant to trimethoprim/sulphamethoxazole. In half of the patients with A. haemolyticum it was the only bacterial pathogen isolated, while in the remainder, beta-haemolytic streptococci were also detected. As expected, beta-haemolytic streptococci were much more frequent than A. haemolyticum in the throat cultures.
Stability of functional outcomes following transitional living programme participation: 3-year follow-up.
The functional status and perceived problems of 21 persons with severe brain injury were reported at admission, and at 1 and 3 years post-discharge from a community-based post-acute rehabilitation programme. Functional status was measured by participation in productive activity, financial support, place of residence and level of supervision required. Improvements observed at 1-year follow-up remained stable or had improved at 3-year follow-up. Loneliness and depression, while not reported at admission, increased over time to become the two problems reported most frequently at 3-year follow-up.
c-myc expression correlates with suppression of c-kit protooncogene expression in small cell lung cancer cell lines.
The mRNAs encoding the c-kit protooncogene tyrosine kinase receptor and its ligand, hemopoietic stem cell factor, are coexpressed in the majority of small cell lung cancer cell lines, suggesting that an autocrine growth loop may exist. Functional c-kit protein levels correspond well with mRNA levels in these cells. We have observed that those cell lines which express the c-kit gene also express either the L- and N-myc genes; those cell lines which express the c-myc gene do not express the c-kit gene. We have determined, by analyzing several small lung cancer cell lines transfected with a c-myc expression vector, that heterologous expression of c-myc correlates with a marked down-regulation of c-kit expression. Regulation of c-kit expression by the myc gene family may be partly responsible for the differing biological properties of cell lines and tumors which express N- and L-myc versus those that express c-myc.
DNA twisting and the effects of non-contacted bases on affinity of 434 operator for 434 repressor.
The bacteriophage 434 repressor regulates gene expression by binding with differing affinities to the six operator sites on the phage chromosome. The symmetrically arrayed outer eight base pairs (four in each half-site) of these 14-base-pair operators are highly conserved but the middle four bases are divergent. Although these four base pairs are not in contact with repressor, operators with A.T or T.A base pairs at these positions bind repressor more strongly than those bearing C.G or G.C, suggesting that these bases are important for the repressor's ability to discriminate between operators. There is evidence that the central base pairs influence operator function by constraining the twisting and/or bending of DNA. Here we show that there is a relationship between the intrinsic twist of an operator, as determined by the sequence of its central bases, and its affinity for repressor; an operator with a lower affinity is undertwisted relative to an operator with higher affinity. In complex with repressor, the twist of both high- and low-affinity operators is the same. These results indicate that the intrinsic twist of DNA and its twisting flexibility both affect the affinity of 434 operator for repressor.
Evaluation of platelet surface antigens by fluorescence flow cytometry.
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A mentorship program for minority students.
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Use of recovery VO2 to predict running economy.
The purpose of this study was to determine whether running economy (RE) could be predicted accurately using recovery VO2 values. Twelve runners (means VO2max = 61.9, SD 4.9 ml.kg-1.min-1) completed three treadmill RE sessions over a 2-week period. During each session, subjects performed three 6-min runs at 69%, 78%, and 87% VO2max. RE was calculated from a single 2-min gas collection during the last 2 min of running. Immediately following each run, recovery VO2 data obtained during randomly assigned 15-s, 20-s, or 25-s gas collections were used to predict exercise VO2. Correlations and mean absolute percentage variation (% VAR) between actual and predicted VO2 at each relative intensity and recovery period are reported. Although the relationship between actual and predicted VO2 was significant and more pronounced at higher exercise intensities, the overall magnitude of the association was low to moderate (r range = 0.50-0.81). The range of % VAR between actual and predicted aerobic demands also obscured marked underprediction (-6.5% to -12.5%) and overprediction (+10.1% to +17.4%) of actual VO2 in some subjects. These data suggest that 15-, 20-, and 25-s recovery VO2 values do not correlate strongly with steady-state VO2, nor do they adequately account for variation in individual economy profiles.
A safe route for deep pelvic biopsy with distention of the iliacus muscle.
To avoid bowel perforation during deep pelvic biopsy, the authors describe a technique in which the iliacus muscle is distended by injecting it with a solution of lidocaine and saline. This muscle distention causes sufficient bowel displacement to allow safe advancement of biopsy needles as large as 14 gauge through the distended muscle belly to the region of interest.
A prospective study of the clinical utility of lymphocyte monitoring in the cardiac transplant recipient.
Monitoring peripheral lymphocytes for changes in antigen expression or subpopulations was performed by flow cytometry in an attempt to identify infection or rejection in cardiac transplantation recipients (CTRs). In this study, 32 cardiac transplantation recipients were followed prospectively, and the results of 274 lymphocyte analyses for transferrin receptor expression, an indicator of lymphocyte activation, and CD4/CD8 lymphocyte ratios were correlated with the patient's clinical status, e.g., infection (early or late), rejection (mild, moderate, or severe), or quiescence. The percentage of lymphocytes expressing the transferrin receptor (%TR+) increased significantly during all stages of infection (2.9%, P = 0.02), or stratified into early (2.7%, P = 0.03) or late stage infection (2.6%, P = 0.03). The increase in %TR+ lymphocytes was also noted during mild (2.8%, P = 0.01) and moderate (3.0%, P = 0.008) rejection. The specificity and positive predictive value of an increased %TR+ lymphocyte was 97% and 93%, respectively, during early infection; 92 and 71%, respectively, during mild rejection; and 85 and 80%, respectively, during moderate rejection. The CD4/CD8 lymphocyte ratio did not correlate with either infection or rejection (P greater than 0.05). In conclusion, an increase in the %TR+ lymphocytes indicates the presence of infection, especially acute infection, or, less likely, rejection in the cardiac transplant recipient, but its clinical utility may be as a screening test for the presence of infection, especially early infection in CTRs during the posttransplantation period. The CD4/CD8 lymphocyte ratio does not correlate with the presence of infection or rejection in the CTR.
Transferrin receptors and CD4/CD8 lymphocyte ratios in rejection and infection in cardiac transplantation recipients.
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