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Biomedical subjects

J Timmer

Publications and source records attributed to J Timmer.

83 records · Page 5Linked to original sources
PubMed1990

Ultrastructure of neutrophilic granulopoiesis in the bone marrow of patients with chronic myeloid leukemia (CML). A morphometric study with special emphasis on azurophil (primary) and specific (secondary) granules.

In seven patients with chronic myeloid leukemia (CML) and ultrastructural and morphometric study was performed on neutrophilic granulopoiesis in bone marrow trephine biopsies. Bone marrow specimens from five patients without hematological abnormalities served as controls. In stable phases of CML, abnormalities of the maturing granulocytic lineage were most conspicuously expressed by an infrequently occurring nuclear disfiguration (blebs and disturbed bridging of segments). Morphometric evaluation included the numbers of azurphil (primary) and specific (secondary) granules, the cisternal length of the endoplasmic reticulum and the area of the mitochondrial profiles. These variables could be determined in early and late myeloblasts, promyelocytes, metamyelocytes, band cells and mature polymorphonuclear granulocytes. Statistical analysis with regard to control specimens demonstrated no significant differences in the total amount of neutrophil granules or of the other cell organelles.

Bone Marrow↗
PubMed1983

[What does the family think? Results of a survey among visitors to the medical care department of a nursing home].

In order to obtain a fuller understanding of the various ideas behind the evaluation of care as provided by nursing homes, 42 regular and frequent visitors of a nursing home, participated in 'open-attitude' interviews. These people had to a great extent adapted their way of life to their regular visits to the nursing home. These relatives of nursing home residents clearly have one common denominator in their various considerations of such care and that is the strong emphasis which in every aspect was placed upon the extent of individual attention given to the residents. The combined functions fulfilled by the nursing home physician, both as a manager of the nursing home and as a general practitioner for the residents, was more than once a subject for discussion by the relatives. These visitors feel the need for the institution of a 'hostess function' (as the investigators formulate it) on the nursing ward. This function should be used in order to provide particular attention to the residents of the nursing home, and should not be too rigidly tied to the (otherwise necessary) institutional routine. A further participation of relatives in certain aspects of care seems quite attainable.

Aged↗
PubMedDate not supplied

Parameter identification in dynamical models of anaerobic waste water treatment.

Biochemical reactions can often be formulated mathematically as ordinary differential equations. In the process of modeling, the main questions that arise are concerned with structural identifiability, parameter estimation and practical identifiability. To clarify these questions and the methods how to solve them, we analyze two different second order models for anaerobic waste water treatment processes using two data sets obtained from different experimental setups. In both experiments only biogas production rate was measured which complicates the analysis considerably. We show that proving structural identifiability of the mathematical models with currently used methods fails. Therefore, we introduce a new, general method based on the asymptotic behavior of the maximum likelihood estimator to show local structural identifiability. For parameter estimation we use the multiple shooting approach which is described. Additionally we show that the Hessian matrix approach to compute confidence intervals fails in our examples while a method based on Monte Carlo Simulation works well.

Anaerobiosis↗
PubMedDate not supplied

Use of sodium hydroxide solution to clear partially occluded vascular access ports.

Gradual vascular access port or tunneled central venous catheter occlusion during total parenteral nutrition is a common complication of unknown etiology, usually unresponsive to treatment with urokinase, ethanol, or hydrochloric acid. After establishing safety with regard to catheter materials and efficacy in dissolving the occluding substance in vitro, we treated a total of 13 vascular access ports (10 patients) that had occluded gradually during "three-in-one" total parental nutrition by slow perfusion with 10 to 20 mL of 0.1 mmol/mL sodium hydroxide solution. We found a mean increase in flow (results are flow rates under gravity-dependent vascular access port inlet pressure of 1.5 kPa) from 37 microL/s (95% upper confidence limit, 45 microL/s) to 75 microL/s (95% lower confidence limit, 64 microL/s; p < .001). For normal use, a flow of 50 microL/s is sufficient. There were no side effects. Five vascular access ports remained in excellent function during a follow-up period of 9 months. The others had reocclusions, but the partial reocclusions could be treated successfully.

Catheters, Indwelling↗