Sample suitability for the detection of minor white cell populations (microchimerism) by polymerase chain reaction

BACKGROUND: There is increasing use of highly sensitive testing with polymerase chain reaction (PCR) to study white cell microchimerism after transfusion and transplantation. This study investigated possible artifactual sources of allogeneic sample contamination before PCR testing. STUDY DESIGN AND METHODS: Quantitative Y-chromosome PCR was used to study microchimerism among transfused patients with sickle cell disease (SCD) and thalassemia by using residual specimens from the clinical laboratory. High levels of circulating male white cells among transfused patients with SCD but not thalassemia led to concern over the artifactual origin of male cells. To investigate, paired specimens were collected from 26 female SCD patients: one specimen underwent processing only for PCR, while the other underwent testing in the clinical laboratory before PCR as a process control. All laboratory instruments were also assessed for their ability to impart male allogeneic cells to aliquots of female blood. RESULTS: Thirty-three (31%) of 107 SCD samples, but 0 of 20 thalassemia samples, gave a high-level PCR signal. One of 26 paired samples that was not exposed to clinical laboratory equipment had low-level PCR positivity while 10 of the 26 became strongly positive after testing on a blood cell analyzer and a reticulocyte analyzer. Sixteen of 32 female samples became positive after reticulocyte analysis, while none became positive after blood cell analysis. Samples from thalassemia patients tested PCR-negative because reticulocyte counts had not been performed. CONCLUSION: Allogeneic cell contamination is common with clinical laboratory equipment. These samples may not be suitable for microchimerism studies. In addition to method controls, process controls should be employed where appropriate.     

Arteriolar reactivity in conscious diabetic rats: influence of aminoguanidine treatment

The effect of 6 weeks' streptozotocin (STZ)-induced (70 mg/kg) diabetes and aminoguanidine (AG) treatment (50 mg/kg s.c. or 250-750 mg/l given in drinking water) on arteriolar reactivity to vasoactive substances was investigated in conscious rats. Studies were performed in untreated control rats (n = 13), STZ-induced diabetic rats (n = 11), AG-treated control rats (n = 12), and AG-treated diabetic rats (n = 12). Rats were provided with a dorsal microcirculatory chamber that allowed intravital microscopy of striated muscle arterioles of varying diameter (A1, large; A2, intermediate; and A3, small arterioles) in conscious animals. The mean arterial pressure (MAP) and arteriolar diameter responses to intravenous infusion of the following drugs were examined: the endothelium-dependent vasodilator acetylcholine (ACh; 3, 10, and 30 microg x kg(-1) x min(-1)), the potassium-channel opener levcromakalim (LC; 30 microg/kg), and the vasoconstrictor agents ANG II (0.1 and 0.3 microg x kg(-1) x min(-1)) and norepinephrine (NE; 0.2, 0.6, and 2.0 microg x kg(-1) x min(-1)). Baseline MAP was lower in both diabetic groups versus the nondiabetic groups (P < 0.05). AG treatment had no influence on baseline MAP. The absolute change in MAP after drug infusion tended to be lower in the diabetic rats than in their nondiabetic littermates. Arteriolar vasodilatory responses to ACh and LC were attenuated in the diabetic animals (1 +/- 7 vs. 19 +/- 7% [P < 0.05] and 7 +/- 3 vs. 34 +/- 8% [P < 0.01] in A2, respectively). AG treatment of diabetic animals did not prevent the development of this disturbance. Vasoconstrictor responses were not influenced by the diabetic state. In the intermediate arterioles of AG-treated control rats, a hyperresponse was observed after ANG II infusion (-10 +/- 2 vs. -2 +/- 2%; P < 0.05) and a hyporesponse was observed after ACh and LC infusion (2 +/- 3 and 15 +/- 6%, respectively; P < 0.05 vs. untreated control rats). These data indicate that 6 weeks of experimental diabetes is associated with a decreased endothelium-dependent and -independent vasodilatation. AG treatment had no beneficial effect on this disturbance.     

There's more to the picture than meets the eye: young children's difficulty understanding biased interpretation

5 experiments investigated children's understanding that expectations based on prior experience may influence a person's interpretation of ambiguous visual information. In Experiment 1, 4- and 5-year-olds were asked to infer a puppet's interpretation of a small, ambiguous portion of a line drawing after the puppet had been led to have an erroneous expectation about the drawing's identity. Children of both ages failed to ascribe to the puppet an interpretation consistent with the puppet's expectation. Instead, children attributed complete knowledge of the drawing to the puppet. In Experiment 2, the task was modified to reduce memory demands, but 4- and 5-year-olds continued to overlook the puppet's prior expectations when asked to infer the puppet's interpretation of an ambiguous scene. 6-year-olds responded correctly. In Experiment 3, 4- and 5-year-olds correctly reported that an observer who saw a restricted view would not know what was in the drawing, but children did not realize that the observer's interpretation might be mistaken. Experiments 4 and 5 explored the possibility that children's errors reflect difficulty inhibiting their own knowledge when responding. The results are taken as evidence that understanding of interpretation begins at approximately age 6 years.     

The Dutch Renal Artery Stenosis Intervention Cooperative (DRASTIC) Study: rationale, design and inclusion data

RATIONALE: Renal artery stenosis may lead to renovascular hypertension, risking multiple organ damage including damage to the contralateral kidney. Progression of stenosis may impair the function of the affected kidney. It is important to identify individuals with this disease among hypertensive patients. The first aim of the Dutch Renal Artery Stenosis Intervention Cooperative (DRASTIC) study is to assess the prevalence of renal artery stenosis in patients with well-defined forms of drug-resistant hypertension, and to determine the predictive value of clinical characteristics and diagnostic tests in these pre-selected patients. With regard to treatment, the effect of renal angioplasty on hypertension is disappointing in atherosclerotic stenosis and technical failure frequently occurs. Therefore, the second aim is to compare the effects of balloon angioplasty and antihypertensive medication on blood pressure in patients with atherosclerotic renal artery stenosis. DESIGN HYPERTENSIVE: patients receiving standard antihypertensive medication in whom diastolic blood pressure remained > or =95 mmHg during three consecutive visits to the outpatient clinic underwent full diagnostic work-up, including renal arteriography. The prevalence of renal artery stenosis in this well-defined patient group was then established, and the predictive value of the various diagnostic tests was assessed. Patients with an atherosclerotic renal artery stenosis of > or =50% were then randomly assigned to balloon angioplasty or to treatment with antihypertensive drugs. After 1 year of intensive follow-up of blood pressure and renal function, re-arteriography was performed. CONCLUSION: In total, 1205 patients have been included in the study, about 500 have received diagnostic work-up, and it is expected that 100 patients will be randomly assigned for renal angioplasty or medical treatment.     

Syndromes and arthritis

There are many questions and no clear answers raised by these children. These syndromes, however, seem to be biologic experiments of nature and present unique opportunities to study the various elements involved in the pathogenesis of arthritis. Pediatric rheumatologists are in a unique position to study these syndromes.     

Endodontic obturation using the MicroSeal technique

In obturating the canal there is no such thing as too thorough or too complete. (Figure 17) But many other systems leave you guessing: Did I push too hard? Did it go to full length? Is what I'm seeing really gutta percha or just the solid core? With Micro-Seal, however, you place the Master Cone, maintain control over the delicate apical region and seal the full length of the canal quickly and simply.     

Coliform inhibition by bacteriocin-like substances in drinking water distribution systems

Bacterial isolates from an unchlorinated potable groundwater system and a chlorinated surface water system were screened by an agar overlay method for the ability to produce bacteriocin-like substances (BLS) inhibitory to the growth of Escherichia coli, Klebsiella sp., and Enterobacter aerogenes. The production of coliform-specific BLS by noncoliform bacteria varied with the site and date of isolation as well as the genus of the producer strain. A total of 448 bacterial isolates were screened from the chlorinated system, and 22.1% produced BLS specific for at least one of the three coliforms. In the unchlorinated system, 7.9% (n = 696) possessed this ability. Flavobacterium/Moraxella comprised 57.1% of all bacteria (from both systems) producing BLS. The possibility that BLS interfere with coliform detection in standard bacteriological water quality tests is discussed.     

Endodontic cleaning and shaping: current concepts

Temperature-sensitive (ts) mutant E/1/3 of Salmonella enteritidis was selected to evaluate its capacity to induce protective responses after peroral (p.o.) or intragastric (i.g.) inoculation to mice. This ts mutant of coasting phenotype was detected in Peyer's patches until day 4, and in spleen by days 3 and 4 after the mice were inoculated by the p.o. route with 10(10) colony forming units. Peroral immunization induced significant protection from oral challenge with 240 LD50 of the wild-type (wt) strain. Higher protection was achieved when the animals were boosted intraperitoneally after p.o. immunization. Intragastric inoculation with the same dose of the ts mutant increased both the level of protection, and colonization and persistence of the micro-organism in Peyer's patches and spleen. Immunization with a single i.g. inoculation induced 70% protection from p.o. challenge of the animals with the wt S. enteritidis. Two i.g. immunizations with E/1/3 raised the level of protection to 90%. Specific IgG, IgM and IgA antibodies, measured in plasma using a micro-ELISA method, were detected after i.g. immunization with ts mutant E/1/3. In addition, specific antibody-secreting cells were detected by means of an ELISPOT assay in spleen and mesenteric nodes of mice immunized with the ts mutant.