Biomedical subjects

R Schaub

Publications and source records attributed to R Schaub.

32 records · Page 2Linked to original sources

PubMed1999

Long-term telemetry of heart rates and energy metabolic rate during the diurnal cycle in normothermic and torpid African blue-naped mousebirds (Urocolius macrourus).

Colies are one of the phylogenetically oldest groups among the modern birds; the earliest finds are from about 35 million years ago. In states of energy deficiency they can undergo torpor during the night when metabolic rate and body temperature are decreased drastically to save energy (up to 90%). Here, we report the first measurements of heart rate (HR) by long-term telemetry, in seven individuals of blue-naped mousebirds (Urocolius macrourus); simultaneously and continuously metabolic rate (MR) was determined. HR at night was about 20% below the range of expected values (246/310 bpm). Mean oxygen pulse (O2 output/stroke) in normothermic birds was in a range of 0.019-0.020 ml O2/stroke; during torpor nights this value decreased significantly to 0.0086. Mean cardiac output ranged from 724 to 1214 ml blood/kg per min; in torpid birds this value fell to 400 ml blood/kg per min. Cardiac regulation of metabolic demand within an activity phase (day or night) is mainly achieved by chronotropy. Inotropy contributes at most 25% to the differences in MR between day and night (ca. 40%). Entry into torpor is brought about mainly by changes in HR (decrease from 240 to 90 bpm); after torpor levels have been reached, there is an increase in HR (to 200 bpm) and a sharp decrease (-53%) in stroke volume. This regulation by inotropy is also characteristic of arousal from torpor.

Adaptation, Physiological↗

PubMed1999

Recombinant human interleukin-11 is unlikely to stimulate the growth of the most common solid tumors.

Recombinant human interleukin-11 (rhIL-11) has been shown to enhance recovery from thrombocytopenia and mucosal injury after cancer chemotherapy. Since RNA for the receptor and signal transducer for IL-11 is detected in many cell types including some cancer cells, it was theoretically possible that rhIL-11 could affect the growth of tumor cells. This study was intended to determine whether rhIL-11 stimulates the proliferation of human tumor colony-forming units (TCFUs) taken directly from patients. Tumor cells were cultured in soft agar and continuously exposed to three concentrations of rhIL-11 (1.0, 10.0 and 100.0 U/ml) for 14 days in the capillary cloning system. Growth stimulation was noted in two of 66 (3%) of evaluable specimens, including one of 14 evaluable non-small cell lung cancer and one of five evaluable colon cancer specimens. In these two specimens, there was no increased stimulation of TCFUs with escalating concentrations of rhIL-11. Interestingly, the highest concentration of rhIL-11 tested inhibited the growth of 16 specimens (24.2%; 95% confidence interval 13.9-34.5%). Growth inhibition demonstrated a concentration-response relationship (p < 0.001). These results suggest that rhIL-11 appears unlikely to stimulate the growth of the most common solid tumors.

Antineoplastic Agents↗

PubMed1998

Preclinical studies of recombinant factor IX.

Recombinant factor IX (rFIX) has been extensively evaluated in preclinical studies. Dog model study of hemophilia B indicated that rFIX was as effective as a highly purified plasma-derived replacement factor in normalizing indices of hemostasis. Pharmacokinetic studies indicated a dose-proportional profile for rFIX. Pharmacokinetic/pharmacodynamic analysis showed that increases in the plasma concentration of rFIX following administration were closely correlated with measured factor IX activity in the plasma. Appropriate in vitro and in vivo toxicology studies have been performed to support the clinical use of rFIX for the treatment of hemophilia B. Finally, experiments in a model of thrombogenicity indicated that in animals rFIX has a low thrombogenic potential. The preclinical results provided a basis for proceeding with human clinical trials.

Animals↗

PubMed1995

Predictive marker for the development of cerebral toxoplasmosis in patients with human immunodeficiency virus type 1.

Explore the source record for details and available documents.

Adult↗

PubMed1993

Recombinant human interleukin-11 stimulates megakaryocytopoiesis and increases peripheral platelets in normal and splenectomized mice.

The effects of recombinant human interleukin-11 (rhIL-11) on in vivo mouse megakaryocytopoeisis were examined. Normal C57Bl/6 mice and splenectomized C57Bl/6 mice were treated for 7 days with 150 micrograms/kg rhIL-11 administered subcutaneously. In normal mice, peripheral platelet counts were elevated compared with vehicle-treated controls after 3 days of rhIL-11 treatment and remained elevated until day 10. Splenectomized mice treated with rhIL-11 showed elevated peripheral platelet counts that were similar in magnitude to normal rhIL-11-treated mice. However, on day 10 the platelet counts in rhIL-11-treated, splenectomized mice were no longer elevated. Analysis of bone marrow megakaryocyte ploidy by two-color flow cytometry showed an increase, relative to controls, in the percentage of 32N megakaryocytes in both normal and splenectomized animals treated with rhIL-11. In normal mice, the number of spleen megakaryocyte colony-forming cells (MEG-CFC) were increased twofold to threefold relative to controls after 3 and 7 days of rhIL-11 treatment, whereas the number of bone marrow MEG-CFC were increased only on day 7. The number of MEG-CFC in the bone marrow of rhIL-11-treated, splenectomized mice was increased twofold compared with controls on both days 3 and 7 of the study. These data show that in vivo treatment of normal or splenectomized mice with rhIL-11 increased megakaryocyte progenitors, stimulated endoreplication of bone marrow megakaryocytes, and increased peripheral platelet counts. In addition, results in splenectomized mice showed that splenic hematopoiesis was not essential for the observed increases in peripheral platelets in response to rhIL-11 administration.

Animals↗

PubMed1986

Dentist and patient appraisal of complete dentures in a Dutch elderly population.

The majority of the Dutch elderly population wears full dentures. According to clinical standards these dentures are often of a poor quality. The treatment demand, however, is small. The purpose of the present study is to describe the quality of dentures by means of clinical criteria on the one hand and judgments of the patients on the other. 131 denture-wearing individuals, with a mean age of 71, participated. A "denture quality" scale was constructed, consisting of five clinical parameters. The judgments of the respondents were recorded in terms of complaints and satisfaction with the dentures. The results show weak or nonsignificant correlations between the denture quality and the subjective measures. After dichotomizing the denture quality score (treatment need vs no treatment need), however, the poorer dentures appeared to be related to more complaints. It was concluded that for planning purposes it seems valid to use clinical figures. On the individual level the prediction of the subjective appraisal of full dentures on the basis of a clinical appreciation appears not to be adequate.

Aged↗

PubMed1986

Denture problems and the quality of life in a Dutch elderly population.

The quality of complete dentures among the Dutch elderly population is often rather poor. Besides, complaints are frequently reported. It is unclear whether these denture problems affect the quality of life. In this study the relationship between the presence of denture problems and the perceived quality of life was considered. Thirty-one edentulous individuals, over 55 yr of age, were interviewed and clinically examined. The results show a significant relationship between the denture variables "quality", "satisfaction" and "complaints". Quality of life is weakly correlated with the quality of the dentures, but not with the other main denture variables. Some implications of these findings are briefly discussed.

Aged↗

PubMed1981

Refractoriness of both uterus and mammary gland of the cow to prostaglandin F2 alpha administration:P clinical application.

Uterine and mammary pressure changes were simultaneously measured in lactating nonpregnant cows injected (IV) with different doses (0.1 to 32.0 mg) of prostaglandin F2 alpha (PGF2 alpha). The total work of the uterus increased up to 250% of base-line value as the dose of PGF2 alpha was increased. But, a dose-response relationship was not seen in the uterus. Partial refractoriness was developed in the uterus, and total refractoriness was developed in the mammary gland. Further challenge with oxytocin (30 U) elicited significant responses in both the uterus and the mammary gland. Because of the development of refractoriness and side effects, PGF2 alpha is not recommended as a drug to be used when mechanical evacuation (free of endocrine effect) of the uterus or mammary gland (or both) is indicated.

Animals↗

PubMed1973