Biomedical subjects

I Bar-Kana

Publications and source records attributed to I Bar-Kana.

5 recordsLinked to original sources

PubMed2002

Bone morphogenetic protein 2 induces the expression of cementum attachment protein in human periodontal ligament clones.

Cementum is continuously formed during the lifetime of a tooth. The paravascular zones in the adult periodontal ligament (PL) comprise the progenitors for the fibroblastic (Fb) lineage and mineralized tissue-forming (MTF) cell lineages--the osteoblastic (Ob) and cementoblastic (Cb) lineages. Recent studies indicate that cementum attachment protein (CAP) is related to the differentiation of the Cb lineage and is instrumental in differentiating between the three periodontal cell lineages. The purpose of this study was to assess the effect of bone morphogenetic protein 2 (BMP2) on the expression of cementum attachment protein (CAP) and on the differentiation of cloned PL progenitors. The effect of BMP2 on CAP expression and on the differentiation of cloned Fb and MTF progenitors was tested by assessing the expression of alkaline phosphatase (ALP), CAP, and bone sialoprotein (BSP) by immunochemistry and by determining the CAP-binding capacity of these clones. Untreated Fb clones were negative for all tested markers and had low CAP-binding capacity. Untreated MTF clones had a high CAP-binding capacity and were positive for the three markers. BMP2 enhanced the CAP-binding potential of both Fb and MTF clones. BMP2 induced the expression of CAP, ALP, and BSP in the Fb clones and enhanced the expression of CAP and BSP in the MTF clones. These results indicate for the first time that BMP2 can recruit progenitors to the Cb lineage and regulate the differentiation of the Cb lineage by inducing and enhancing the expression of CAP, a cell lineage-specific regulator. Furthermore, the results suggest that the MTF and Fb lineages may originate from a common early progenitor cell.

Alkaline Phosphatase↗

PubMed2002

Immunolocalization of a human cementoblastoma-conditioned medium-derived protein.

Little is known about the molecular mechanisms that regulate the cementogenesis process, because specific cementum markers are not yet available. To investigate whether a cementoblastoma-conditioned medium-derived protein (CP) could be useful as a cementum biological marker, we studied its expression and distribution in human periodontal tissues, human periodontal ligament, alveolar bone, and cementoblastoma-derived cells. In human periodontal tissues, immunoreactivity to anti-CP was observed throughout the cementoid phase of acellular and cellular cementum, cementoblasts, cementocytes, cells located in the endosteal spaces of human alveolar bone, and in cells in the periodontal ligament located near the blood vessels. Immunopurified CP promoted cell attachment on human periodontal ligament, alveolar bone-derived cells, and gingival fibroblasts. A monoclonal antibody against bovine cementum attachment protein (CAP) cross-reacted with CP. These findings indicate that CP identifies potential cementoblast progenitor cells, is immunologically related to CAP species, and serves as a biological marker for cementum.

Adult↗

PubMed1998

Cementum attachment protein manifestation is restricted to the mineralized tissue forming cells of the periodontium.

The mechanisms that regulate cementogenesis are mainly unknown. A specific cementum attachment protein (CAP) has been recently partially characterized and found to be more efficient in supporting the attachment of alveolar bone cells (ABC) and periodontal ligament cells (PLC) than that of gingival fibroblasts (GF). The purpose of this study was to determine the capacity of human periodontal-derived cells to bind and express CAP and to relate these properties to their capacity to express alkaline phosphatase (AlP) and form mineralized tissue (MTF). ABC, PLC and GF were tested. Human stromal bone marrow cells (SBMC) and a cementoma-derived cell line (CC) served as controls. CAP binding was determined using 125I-CAP. The amount of MTF was assessed by alizarin red staining and image analysis determination of the amount of red-stained material. AlP and CAP expression were examined by histochemistry and immunochemistry, respectively. The highest expression of CAP was observed in CC, followed by PLC and ABC in decreasing order, whereas SBMC and GF did not express CAP. SBMC manifested the highest CAP binding capacity followed by CC, ABC, PLC and GF. MTF and AlP manifestation were greatest in SBMC, followed by ABC, PLC and CC. Collectively the results indicate that CAP binding and secretion are not linked and that CAP manifestation is restricted to periodontal derived cell lineages with the potential of forming mineralized tissues.

Alkaline Phosphatase↗

PubMed1997

A robust sensor fusion method for heart rate estimation.

PROBLEM: Physiologic data measured in the clinical environment is frequently corrupted causing erroneous data to be displayed, periods of missing information or nuisance alarms to be triggered. To date, the possibility of combining sensors with similar information to improve the quality of the extracted data has not been developed. The objective of this work is to develop a method for combining heart rate measurements from multiple sensors to obtain: (i) an estimate of heart rate that is free of artifact; (ii) a confidence value associated with every heart rate estimate which indicates the likelihood that an estimate is correct; (iii) a more accurate estimate of heart rate than is available from any individual sensor. SOLUTION: The essence of the method is to discriminate between good and bad sensor measurements and combine only the good readings to derive an optimal heart rate estimate. Past estimates of heart rate are used to derive a predicted value for the current heart rate that is also fused along with the sensor measurements. Consensus between sensor measurements, the predicted value and physiologic credibility of the readings are used to distinguish between good and bad readings. Three sensor measurements and the predicted value are evaluated yielding 16 possible hypotheses for the current state of the available data. A Kalman filter uses the most likely hypothesis to derive the fused estimate. Statistical measures of the sensor error and rate of change of heart rate are adaptively estimated when data are sufficiently reliable and used to enhance the hypothesis selection process. DISCUSSION: The method of sensor fusion presented has been documented to perform well using clinical data. Limitations of the technique and the assumptions employed are discussed as well as directions for future research.

Electrocardiography↗

PubMed1997

Robust sensor fusion improves heart rate estimation: clinical evaluation.

OBJECTIVE: To determine if Robust Sensor Fusion (RSF), a method designed to fuse data from multiple sensors with redundant heart rate information can be used to improve the quality of heart rate data. To determine if the improved estimate of heart rate can reduce the number of false and missed heart rate alarms. METHODS: A total of 85 monitoring periods were investigated, 12 from the operating room, 60 from adult ICU and 13 from pediatric ICU. The operating room periods began with induction of anesthesia and ended at the completion of the anesthetic. For the ICU data, four hour blocks of time were studied. For each monitoring period, HR values were recorded at 5 second intervals or less from the ECG, SpO2 and IAC using a SpaceLabs Medical Gateway connected to a SpaceLabs Medical PC2. Fused estimates of HR were derived for every time point using RSF and all results accepted regardless of confidence value. Data were annotated manually to identify the "reference" HR (that HR value most likely to be correct) at all time points. All HR values from the sensors and the fused estimate that were different from the reference HR by more than +/- 5 beats/min were considered inaccurate. For each monitoring period, the total time per hour that data were either inaccurate or unavailable was calculated for each sensor as well as the fused estimates. The total time of false and missed HR alarms was found for all sensors and the fused estimate by comparing the data to thresholds for both high and low HR alarms at 150 bpm, 130 bpm, 110 bpm and 50 bpm, 40 bpm, 30 bpm respectively. RESULTS: The fused estimate of HR was consistently as good or better than the estimate available from any individual sensor. The fused estimates also consistently reduced the incidence of false alarms compared with individual sensors without an unacceptable incidence of missed alarms. DISCUSSION: Redundancy in sensor measurements can be used to improve HR estimation in the clinical setting. Methods like RSF which improve the quality of monitored data and reduce nuisance alarms will enhance the value of patient monitors to clinicians.

Adult↗