Biomedical subjects

A Guber

Publications and source records attributed to A Guber.

9 recordsLinked to original sources

PubMed1998

The forced expiratory volume-time curve estimation using the electrocardiogram.

The feasibility of estimating the forced expiratory volume-time curve from the amplitude modulation of the electrocardiogram was studied using a numerical torso model and ECG signal processing. A two dimensional numerical model of the torso was solved for the maximum expiration and inspiration to study the changes in the surface potential as a result of changes in the lung volume. The numerical model showed that significant changes in the surface potential amplitude occur between maximum inspiration and maximum expiration and that this amplitude change in the left-right axis of the torso might be three times as large as in the front-back axis. In the experimental setup, ECG waveforms from the surface of the chest and the mouth air flow were simultaneously recorded from four male subjects during several forced vital capacity (FVC) maneuvers. The amplitude of the QRS complex was measured for different expired lung volumes and an estimation of the forced expiratory volume-time curve was obtained. The FVC and the FEV1 (forced expiratory volume after 1 s) spirometry indices were calculated for the two volume-time curves obtained from the electrocardiogram and from the spirometry measurements. The results differ between 0.1 and 0.8 1. These preliminary results are encouraging and might indicate that a relationship between the volume-time curve during FVC test and the electrocardiogram signals does exist. Further validation in a larger number of subjects and patients is needed before the technique can be applicable for clinical use.

Adult↗

PubMed1997

The prognostic application of cytokeratin typing of nonsmall cell lung carcinoma. A retrospective study.

BACKGROUND: In a previous study, the authors used a variety of anticytokeratin monoclonal antibodies to show that a large proportion of lung tumors cytologically diagnosed as squamous cell carcinoma contain cells expressing simple epithelial cytokeratins, suggesting that these tumors have their origin in adenocarcinoma. These findings raised the possibility that cytokeratin (CK) typing might have a diagnostic capacity not attainable by standard histopathology. The aim of the current study was to assess the value of CK typing for this purpose by determining the correlation between the diagnosis of lung tumors based on CK typing and the survival rate of the patients. METHODS: Paraffin embedded tissue sections of 66 nonsmall cell lung carcinoma (NSCLC) specimens were examined. These included 18 adenocarcinomas, 32 squamous cell carcinomas, and 16 undifferentiated carcinomas, all diagnosed surgically and histopathologically, and further classified as either Stage I or II. CK typing was performed using the streptavidin-biotin-peroxidase method, employing the following anti-CK monoclonal antibodies: Ks.B.17 (which reacts with CK 18), A3-3 (which reacts with CK 13), and E5-9 (which reacts with CK 10). RESULTS: Comparison between the 5-year survival rates (5 ysr) of patients with different NSCLC indicated that all types of Stage II tumors had a much poorer prognosis than Stage I tumors. Differences found in the 5 ysr among patients with different types of Stage I tumors were not statistically significant (adenocarcinomas, 33% 5 ysr; squamous cell carcinomas, 59% 5 ysr; undifferentiated carcinomas, 36% 5 ysr; all diagnosed by conventional histopathology). Similarly, no significant differences were noted in 5 ysr between patients with tumors stained positively or negatively with monoclonal antibodies A3-3 or E5-9 (anti-CK 13 and anti-CK 10, respectively). In contrast, highly significant differences (P = 0.002) were found in the 5 ysr between patients with Stage I tumors positively or negatively stained with monoclonal antibody Ks.B.17 (23% vs. 75% 5 ysr, respectively) regardless of the histologic types of tumors. Especially informative was a combination of immunohistochemical and histologic diagnoses, with best survival rates (87% 5 ysr) in Ks.B.17 negative tumors histologically diagnosed as Stage I squamous cell carcinomas and worst survival rates (14% 5 ysr) in Ks.B.17 positive tumors diagnosed as adenocarcinomas. CONCLUSIONS: The current study showed that CK 18 typing of lung tumors can provide a more accurate diagnosis and therefore facilitate the planning of more suitable therapeutic approaches.

Adenocarcinoma↗

PubMed1996

New model-based indices for maximum expiratory flow-volume curve in patients with chronic obstructive pulmonary disease.

New lung function indices based on a lumped parameter model of the maximal expiratory flow-volume (MEFV) curve are presented. The waveforms obtained by the model were compared to the flow-volume curves recorded from normal subjects and from patients with small airways disease, asthma and emphysema. We were able to reproduce the flow-volume curves using the model and calculate new parameters that indicate the degree of lung function impairment and may be applicable to identify mild chronic obstructive pulmonary diseases. Further studies in larger groups of patients are required to better define the true predictive value of the new indices described for the diagnosis of COPD.

Airway Resistance↗

PubMed1995

Maximum expiratory flow-volume curve: mathematical model and experimental results.

A mathematical simulation of the maximum expiratory flow-volume (MEFV) curve was developed using a lumped parameter model. The model uses a theoretical approximation of an activation function representing the lung's pressure-volume relationship during maximally forced expiration. The waveforms obtained by the model were compared to the flow-volume curves recorded from normal subjects and for patients with small airways disease, asthma, and emphysema. We were able to reproduce the flow-volume curves using the model and calculate new parameters that reflect the dependency of airways resistance on expired volume during FVS manoeuvre. These new parameters are based on the entire information presented in the flow-volume curve and on the reduction in flow at all lung volumes. We also calculated the mean slope of the resistance-expired volume curves obtained from the model by fitting a straight line to the curve. Using representative data for normal and COPD patients different mean slopes of 0.095, 0.13, 0.49 and 1.44 litre-1 were obtained for normal subject, small airways disease, asthma and emphysema patients, respectively. The model-based parameters may be applicable to human studies. However, further studies in large groups of patients are required to better define the true predictive value of the new indices described for the diagnosis of COPD.

Asthma↗

PubMed1994

Microstructure technologies and their potential in medical applications.

One of the major fields of application of microstructure technology and microsystems technology will probably be centered in medical engineering. Above all in neurosurgery, highly sophisticated surgical instruments featuring high functionality combined with high reliability are needed. Products fabricated by conventional manufacturing technologies can fulfill these demanding requirements only to a limited extend. At the Karlsruhe Nuclear Research Center first prototype components such as microspectrometers, microturbines and microfluidics structures are presently fabricated and tested which can be used in future microendoscopes as sensors or actuators. Combined with adequate information processing and suitable interface technology, it will be possible to create microsystems for various medical applications.

Biomedical Engineering↗

PubMed1994

Flow cytometric analysis and cytokeratin typing of human lung tumors. A preliminary study.

In the current study a comparative analysis of keratin typing and DNA content was carried out in human lung tumors from transthoracic fine needle aspiration biopsies (TFNAB) (18 patients) or from surgically resected tumor tissues (14 patients). According to the cytologic and histologic features, 2 of the 32 tumors were diagnosed as benign tumors, 11 as squamous cell carcinomas, 12 as adenocarcinomas, and 7 as undifferentiated large cell carcinomas. Two cases in the adenocarcinoma and one in the undifferentiated large cell carcinoma groups were pulmonary metastasis or second primary tumors. Malignant cells of tumors which reacted positively with KK8.60 anticytokeratin polypeptides No. 10 and 11 (and hence contain keratinizing cells) displayed diploid DNA content in a flow cytometric assay regardless of their cytologic or histologic appearance. In contrast, all tumors which lacked such positive cells (most of which were defined as adenocarcinomas and undifferentiated tumors) were hyperdiploid. The close correlation between high DNA content and both malignancy and the absence of advanced squamous differentiation (keratinization) suggests that such combined analysis may provide new tools for the cytologic diagnosis and prognosis of lung cancers.

Adenocarcinoma↗

PubMed1990

Immunocytochemical characterization of lung tumors in fine-needle aspiration. The use of cytokeratin monoclonal antibodies for the differential diagnosis of squamous cell carcinoma and adenocarcinoma.

In the current study, immunocytochemical typing of intermediate filaments was used for a differential diagnosis of human lung tumors from transthoracic fine-needle aspiration biopsies (TFNAB). The authors have compared the cytologic diagnosis of 53 lung cancer cases with the immunofluorescence patterns obtained using a panel of monoclonal antibodies, five of which (KG 8.13, KM 4.62, Ks B.17, KS 8.12, KK 8.60) react with specific cytokeratin polypeptides and one with vimentin (VIM 13.2). Only in six of 23 samples cytologically diagnosed as squamous cell carcinoma did the immunocytochemical typing of cytokeratins (ICTC) confirm the cytologic diagnosis. In seven cases some of the tumor cells stained positively with antibody Ks B.17 specific for simple epithelial keratin (No: 18), suggesting the presence of some cells of glandular origin. In ten additional cases the ICTC was in conflict with the cytologic diagnosis of squamous cell carcinoma (i.e., antibodies Ks 8.12 and KK 8.60 were negative, and antibody Ks B.17, positive) supporting a diagnosis of adenocarcinoma. In 14 of 18 cases cytologically diagnosed as adenocarcinoma, the ICTC confirmed the diagnosis whereas in four cases additional presence of some squamous cells was noticed. The ICTC labeling of cases cytologically diagnosed as undifferentiated and large cell carcinomas was similar to that of the group of adenocarcinomas. Thus, the application of cytokeratin typing for TFNAB samples seems to provide a vital complementation to routine cytologic study, especially for cases cytologically diagnosed as squamous carcinoma.

Adenocarcinoma↗

PubMed1986

Pulmonary embolism after short-term treatment of acne vulgaris with ovulation suppressor agents.

A case of recurrent pulmonary embolism with infarction is described. The patient, a 28-year-old woman, had been treated over a four-month period with a preparation of cyproterone acetate plus ethinyloestradiol for acne vulgaris. It is suggested that the use of oral contraceptive preparations for the treatment of innocent disorders should be avoided when factors that may potentiate a thrombogenic effect are present.

Acne Vulgaris↗

PubMedDate not supplied

Prognostic significance of p53 and ras p21 protein expression in surgically treated non-small cell lung carcinoma.

BACKGROUND AND OBJECTIVE: The prognosis of surgically treated non-small cell lung carcinoma (NSCLC) varies even after careful selection of the patients; the conventional grading and staging system is often deficient in determining which cases will profit best from surgery. Additional techniques are needed to permit better prognostic evaluation. METHODS: In this research, 2 markers of cellular proliferation, p53 and ras (p21) proteins were examined. The material used was from the same series reported previously which were immunostained with different cytokeratin markers for the same purpose. Immunohistochemical stainings of p53 and p21 were performed on the paraffin sections of 88 NSCLC specimens: 45 squamous cell, 22 adeno- and 21 large or undifferentiated carcinomas. RESULTS: At stage I, positive or negative stains of p53 and p21 provided no prognostic information since they had similar 5 year survival rates of approximatively 50% which is similar to the mean predicted survival rate for stage I. In this group as well, there was no significant difference in immunostaining, either in relation to the histological type or grade of the tumors. At stage III-IV, we found a trend, which, however, was not statistically significant, between positive immunostains of p53 and p21 proteins and longer survival. CONCLUSIONS: These results vary from our previous study on the expression of the differentiation marker cytokeratin 18, which showed that positive staining of tumor cells was associated with a statistically significant poorer prognosis at stage I regardless of histological types.

Aged↗