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Biomedical subjects

G Eckert

Publications and source records attributed to G Eckert.

At least 19 recordsLinked to original sources
PubMed2004

The impact of image compression on diagnostic quality of digital images for detection of chemically-induced periapical lesions.

OBJECTIVES: To test the hypothesis that there is no significant difference in the detectability of chemically-induced periapical lesions between a non-compressed image and one subjected to a Joint Photographic Experts Group (JPEG) lossy compression technique at a ratio of 23:1 or less. METHOD: Chemically-induced periapical lesions were created by placing a solution of 70% perchloric acid at the apex of extracted teeth in 13 human jaw cadaver specimens. Acid was applied in seven incremental time periods from 0-32 h. Extracted teeth were replaced in the socket and images were made using the Schick CDR digital sensor. Using a JPEG lossy compression algorithm, five compression ratios of 2:1, 14:1, 23:1, 28:1 and 47:1 were applied to the images. Images were viewed three times by three observers who ranked the presence or absence of a lesion at three sites, the mesial area, distal area and apex of the tooth, on a 5-point confidence scale. Intraobserver and interobserver agreement and agreement between the compressed and the original images were assessed with intraclass correlation coefficients (ICCs). RESULTS: Overall ICCs for measuring intraobserver agreement using all images were 0.77, 0.84, and 0.50 for the three observers, respectively. The overall ICC for assessing agreement between observers was 0.57. There was no significant difference (P>0.05) between compressed and original images for any site at compression ratios of 2:1, 23:1 and 28:1. There were significant differences for a compression ratio of 47:1. CONCLUSION: JPEG compression does not impact detectability of artificial periapical lesions at low and moderate compression ratios up to and including 28:1.

Algorithms↗
PubMed1998

The efficacy and safety of a 10% carbamide peroxide bleaching gel.

OBJECTIVE: A 6-month, double-blind study was undertaken to assess the efficacy and safety of a 10% carbamide peroxide gel designed for at-home tooth bleaching. METHOD AND MATERIALS: Sixty patients were randomized into two equal subgroups balanced by age, gender, and oral health status. Shade guide measurements, color transparency photographs, and colorimeter readings were taken and evaluated at baseline and 1, 2, 3, 6, 12, and 24 weeks. The active phase of treatment lasted 14 days. RESULTS: At 22 weeks postbleaching (week 24 of the study), patients receiving the active agent had a 14.1 rank order difference in the shade guide from baseline, and 66% had a clinically observable color change as determined by photographic assessment. They also had a measurable, statistically significant color change from baseline to 6 months of delta E* = 5.0. The tooth color of maxillary incisors stabilized at week 6 and maxillary canines at week 12. The mean color change lost from weeks 2 to 24 was 45% (in delta E*). Transient tissue and tooth sensitivity, noted in some patients, resolved after treatment was completed. CONCLUSION: The product tested is an effective and safe tooth-whitening agent.

Adult↗
PubMed1997

Comparison of general internists, family physicians, and rheumatologists managing patients with symptoms of osteoarthritis of the knee.

OBJECTIVE: To evaluate the nature, risks, and benefits of osteoarthritis (OA) management by primary care physicians and rheumatologists. METHODS: Subjects were 419 patients followed for symptoms of knee OA by either a specialist in family medicine (FM) or general internal medicine (GIM) or by a rheumatologist (RH). Management practices were characterized by in-home documentation by a visiting nurse of drugs taken to relieve OA pain or to prevent gastrointestinal side effects of nonsteroidal anti-inflammatory drugs (NSAIDs) and by patient report (self-administered survey) of nonpharmacologic treatments. Changes in outcomes (knee pain and physical function) over 6 months were measured with the Western Ontario and McMaster Universities Osteoarthritis Index. RESULTS: Patients of RHs were 2-3 years older (P = 0.035) and tended to exhibit greater radiographic severity of OA (P = 0.064) and poorer physical function (P = 0.076) at baseline than the other 2 groups. In all 3 groups, knee pain and physical function improved slightly over 6 months; however, between-group differences were not significant. Compared to drug management of knee pain by FMs or RHs, that by the GIMs was distinguished by greater utilization of acetaminophen and nonacetylated salicylates (P = 0.008), lower prescribed doses of NSAIDs (P = 0.007), and, therefore, lower risk of iatrogenic gastroenteropathy (P < 0.001). In contrast, patients of RHs were more likely than those of FMs and GIMs to report that they had been instructed in use of isometric quadriceps and range-of-motion exercises (P < or = 0.001), application of heat (P = 0.051) and cold (P < 0.001) packs, and in the principles of joint protection (P = 0.016). Neither physician specialty nor specific management practices accounted for variations in patient outcomes. CONCLUSION: This observational study identified specialty-related variability in key aspects of the management of knee OA in the community (i.e., frequency and dosing of NSAIDs, use of nonpharmacologic modalities) that bear strong implications for long-term safety and cost. However, changes in knee pain and function over 6 months were unrelated to variations in management practices.

Activities of Daily Living↗
PubMed1994

In-office cancer-screening education of primary care physicians.

In a demonstration project, education representatives were trained to perform "academic detailing" of cancer control information for physicians and for staff members of family physicians' offices. One-hour visits were arranged at specific times so as to avoid disruption of patient care activities. The representatives led discussions of salient tissues regarding early detection of cancer at three sites (breast, colon-rectum, and prostate) and left relevant patient education materials. Seventeen visits were made to 11 practices involving 22 physicians and 85 staff members. Ten items were selected as evidence of favorable cancer control activities: ashtrays had been removed from the waiting room, patient information was displayed in a wall rack, medical records contained a method for prompting the physician about preventive or screening services that were due to be performed, a recall system reminded patients of services that were due to be performed, the receptionist was involved, the nurse was involved, American Cancer Society (ACS)-recommended services were used or had been added, the physician talked to other physicians about the visit discussions, services or materials had been requested from the local ACS unit, and staff members or physicians had volunteered to serve the ACS. The compliance rate was 35% at baseline. At post-intervention assessment, the compliance rate had increased by 35%, for a final compliance rate of 70%.(ABSTRACT TRUNCATED AT 250 WORDS)

American Cancer Society↗
PubMed1991

Use of dabsylation, column switching and chiral separation for the determination of a renin inhibitor in rat, marmoset and human plasma.

A high-performance liquid chromatographic method with column switching was developed for the determination of the renin inhibitor Ro 42-5892/001, (S)-alpha-[(S)-alpha-[(tert.-butylsulphonyl)methyl]hydrocinnama mido]-N- [(1S,2R,3S)-1-(cyclohexylmethyl)-3-cylcopropyl-2, 3-dihydroxypropyl]imidazole-4-propionamide methanesulphonate (1:1), in rat, marmoset and human plasma, using a Nucleosil C8 120 (3 microns) stationary phase. Since the analyte and the internal standard are optical isomers, beta-cyclodextrin was used as a mobile phase constituent for their chiral separation. The method took advantage of the characteristics of dabsyl chloride derivatives, namely sensitivity, specificity and, particularly, stability, providing a quantification limit of 5 ng/ml. The accuracy (range of inaccuracy 1-13%) and the inter-assay precision (coefficient of variation range 1.8-9.1%) were acceptable. The method was successfully applied to toxicokinetic studies in rats and marmosets.

Animals↗
PubMed1991

Pentamidine aerosol increases the number of alveolar macrophages in HIV-infected patients.

In order to determine the possible effect of aerosolized pentamidine on the cellular composition of the bronchoalveolar lavage fluid in HIV-infected patients, differential counts of 22 consecutive patients who had been rebronchoscopied after 3-19 months were reviewed. Eleven patients were started on pentamidine prophylaxis subsequent to their first presentation. Eleven patients had never taken pentamidine or had discontinued the prophylactic regimen. Compared to first bronchoscopy, the bronchoalveolar lavage (BAL) from patients on regular prophylaxis revealed a significant increase in absolute alveolar macrophage (AM) counts at second presentation (20.8 +/- 11.2 to 50.3 +/- 39.4 x 10(5) cells/100 ml BAL; P less than 0.01). The AM counts of those without pentamidine remained essentially unchanged. Lymphocytes, including CD4 and CD8 subtypes, and neutrophils did not change over time in either group. The results of this retrospective analysis suggest that, in addition to its antimicrobial action, pentamidine may modulate local lung defence mechanisms, particularly by increasing the absolute number of AM.

Administration, Inhalation↗
PubMed1990

[Acute pneumocystosis during polychemotherapy following the MACOP-B protocol].

Four out of eleven patients--none of them HIV positive--who received treatment for non-Hodgkin lymphoma by the MACOP-B protocol between June 1989 and February 1990 were taken ill during or shortly after the conclusion of the course with fulminant pneumonia necessitating artificial ventilation. In three cases Pneumocystis carinii was identified as the pathogen, and in one patient the diagnosis of pneumocystosis seemed probable. The mean cumulative doses given before the outbreak of pneumonia were as follows: cyclophosphamide 2753 +/- 1161 mg, methotrexate 1590 +/- 667 mg, bleomycin 36 +/- 16.8 mg and prednisone 4378 +/- 1734 mg. The mean haemoglobin concentration was 10.7 +/- 0.5 g/dl, leucocyte count 5250 +/- 2100/microliters, lymphocyte count 1300 +/- 300/microliters and lactate dehydrogenase 227 +/- 34 U/l. The cumulative doses and laboratory findings in the seven patients not affected by pneumocytosis were not significantly different. The patients with pneumonia were supported by mechanical ventilation for 6-26 days and treated with large doses of corticosteroids and co-trimoxazole. One patient died after 17 days' ventilation. Three patients were successfully weaned from the ventilator. Chemotherapy protocols such as MACOP-B predispose to acute Pneumocystis pneumonia. The risk of infection is independent of the cumulative doses of the drugs employed. For this reason, prophylaxis with co-trimoxazole is normally mandatory.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1987

Urinary excretion of mefloquine and some of its metabolites in African volunteers at steady state.

Because of the extremely long terminal elimination half-life of mefloquine it is practically impossible to measure quantitatively its urinary excretion after a single dose. Indeed, a correct estimation would require collection of urine over a period of several months. This difficulty was overcome by measuring excretion in the course of a multiple-dose study when steady-state conditions had been reached. Six male African volunteers were given at an interval of 1 week 250 mg mefloquine base in the form of its hydrochloride. Urine was quantitatively collected from each subject during the 11th week and analyzed for unchanged drug and its alcohol and acid metabolites. Excretion of the unchanged drug and of its acid metabolite amounted respectively to 9% (5.2-13.1%) and 4.2% (2.9-6.2%) of the weekly dose. Concentrations of the alcohol metabolite were too low to be measured.

Adolescent↗
PubMed1987

Atypical diabetes insipidus in small cell lung cancer. Paraneoplastic syndrome or metastatic disease?

A 54-year old man was admitted with extensive disease: small cell lung cancer, and severe central diabetes insipidus. Computer assisted tomography of the brain was negative for metastatic spread to the hypothalamus or pituitary gland. Basic levels of antidiuretic hormone were within normal limits, yet the hormone failed to increase secondary to elevated osmotic load. We hypothesize that in this patient, hypothalamus and pituitary gland were morphologically intact, and that diabetes insipidus was induced by the inhibitory action of ectopic opiates on the release of antidiuretic hormone. Nevertheless, since post-mortem studies were refused, metastatic diabetes insipidus could not be definitely excluded, in which case, the source of plasmatic antidiuretic hormone would be the tumor itself.

Brain Neoplasms↗
PubMed1984

Chloride-induced increase of plasma potassium after transfusion of erythrocytes in dialysis patients.

The transfusion of packed red cells (PRC), though they are depleted in cellular potassium, is thought to result in an increase of serum potassium when transfused to patients on regular hemodialysis treatment. The aim of this study was to prove this hypothesis when transfusion was performed during the dialysis-free interval. The effect of 21 transfusions of 2 units of PRC once washed with 0.9% NaCl was analyzed in 10 anemic patients. A significant increase of plasma potassium from 5.5 to 5.9 mmol/l was observed. Intracellular sodium and potassium after transfusion reflected a mixing of the patients' endogenous and the transfused red cells. However, the excess of cellular chloride introduced by the washing procedure, which was by 27.6 mmol/l higher in the transfused cells, could not be detected in the mixed cell population after transfusion. The rapid chloride shift from the transfused acid red cells into plasma, which is accompanied by a rapid uptake of bicarbonate, is thought to release an equivalent amount of potassium, most likely from muscle or bone and enhances plasma potassium. Transfusion of PRC in the dialysis-free interval seems to be no risk for patients with a plasma potassium below 5 mmol/l. Alternatives are transfusion during dialysis or addition of 20 mmol sodium bicarbonate, when transfusion is performed in the dialysis-free interval.

Adult↗
PubMed1983

Multiple-dose kinetic study of mefloquine in healthy male volunteers.

250 mg mefloquine was administered orally once a week for 21 consecutive weeks to 5 volunteers. Blood samples were collected just before administration of the next dose, and the unchanged drug and its metabolite, Ro 21-5104, were measured in the plasma. The mean plasma levels minima in individual subjects measured at steady state were for mefloquine between 0.56 and 1.25 micrograms/ml, and for the metabolite between 1.47 and 5.55 micrograms/ml. The corresponding metabolite to mefloquine ratios ranged between 2.3 and 8.6. The half-life of mefloquine determined at the end of the trial agreed fairly well with values measured in single dose kinetics. This suggests that induction or inhibition of the metabolizing enzymes did not occur during the period of administration.

Adult↗
PubMed1982

HLA-B27 in possible ankylosing spondylitis with peripheral arthritis.

Among 86 patients selected as possibly having ankylosing spondylitis because of clinical symptoms and radiologically normal sacroiliac joints. HLA-B27 was positive in 41%. Four years later a representative sample of 38 individuals were re-examined and radiographed. HLA-B27 positive patients developed sacroiliitis as defined by radiological criteria twice as often (P less than 0.05). They also showed increased uptake of technetium 99 m upon quantitative scintigraphy with a region of interest method and more often probable or definite ankylosing spondylitis as defined by the New York criteria. Further differences between the HLA-B27 positive and negative follow-up groups concerned the frequency of clinical symptoms and peripheral arthritis. It is suggested that HLA-B27 typing may be helpful both in diagnosis and in judging the prognosis of possible or abortive ankylosing spondylitis.

Adult↗
PubMed1982

Single dose kinetics of mefloquine in man. Plasma levels of the unchanged drug and of one of its metabolites.

Oral single dose kinetics of mefloquine was investigated in 16 male volunteers, 3 Caucasians and 13 African natives. Unchanged mefloquine (= M) and one of its metabolites (= MM) were measured in the plasma. The apparent half-life of absorption of M ranged from 0.36 to 2.0 h, its terminal half-life of elimination from 15 to 33 days. Assuming complete systemic availability, an apparent volume of distribution of 14-29 liters x kg-1 and a total clearance of 18-39 ml x min-1 were derived. MM given orally to mice or rats showed at equal dose the same tolerance as mefloquine. Following oral administration of M to man, plasma levels of MM surpassed those of M, resulting in a 2.4-5.1 larger AUC. However, because of its much smaller apparent volume of distribution, MM may be anticipated to represent only a small percentage of the dose and therefore to contribute only to a minor extent towards the unwanted side effects of the drug.

Adult↗