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Biomedical subjects

A Semjonow

Publications and source records attributed to A Semjonow.

At least 37 records · Page 2Linked to original sources
PubMed1996

Isolation of prostate-derived single cells and cell clusters from human peripheral blood.

The detection of blood-borne prostate cancer (PCA) cells may help with clinical staging and the further understanding of PCA metastases. We discovered prostate-specific antigen (PSA)-positive stained but not PSA mRNA-expressing blood cells by means of cell sorting and PSA reverse transcription-PCR in patients. Therefore, we developed a cytokeratin immunomagnetic method to isolate PSA-positive epithelial cells from the circulating blood of PCA patients. We obtained blood-borne single cells from 6 of 10 PCA patients and clustered cells from 8 of 10 PCA patients. Patients with benign prostate hyperplasia tested negative for cell clusters. The reported isolation method yielded prostate-derived cells or clusters of them from PCA-diagnosed patients.

Humans↗
PubMed1996

Impact of free prostate-specific antigen on discordant measurement results of assays for total prostate-specific antigen.

OBJECTIVES: To determine why various assays for total PSA (t-PSA) produce discordant results in identical serum samples. METHODS: A total of 84 sera from 40 patients with histologically confirmed benign prostatic hyperplasia and from 44 patients with untreated prostate cancer were analyzed with seven assays for t-PSA and the Hybritech research assay for free prostate-specific antigen (f-PSA). Comparison between assays was performed by linear regression of the t-PSA concentrations as well as between the t-PSA concentrations and the f/t-PSA ratios. RESULTS: The coefficients of correlation for the investigated assays versus Hybritech Tandem-E range from 0.96 to 0.99. Nevertheless average PSA concentrations differed significantly from the Tandem-E assay in all assays. Despite a good correlation, some assays showed a regression line with a slope notably different from 1. In these assays, elevated concentrations were observed in sera with a high proportion of f-PSA. CONCLUSIONS: The study illustrates a significant and clinically relevant discordance between reported t-PSA concentrations for identical samples, depending on the assay used and on the contents of f-PSA in the sample. The interpretation of t-PSA concentrations requires awareness of the applied assay as well as the establishment of an assay-specific reference range in order to avoid inappropriate clinical consequences, such as unnecessary biopsies. Respective details must be contained in the laboratory reports. A change of assays without specifically reassessing previously valid reference ranges or the uncritical use of a customarily applied limit of < 4 ng/mL will otherwise be harmful to the patient.

Blood Chemical Analysis↗
PubMed1996

Modified ureteral stripping as an alternative to open surgical ureterectomy.

PURPOSE: Using a compression technique instead of the classical invagination technique in cases of total nephroureterectomy improves traction during transurethral stripping of the ureteral stump. MATERIALS AND METHODS: Eight patients underwent our modified compression technique. After nephrectomy a kinked 5F ureteral catheter is attached to the ureteral stump with a double ligation. Traction on the ureteral catheter is used to achieve ureteral compression. RESULTS: There were no intraoperative difficulties except for 1 dislodged ureteral catheter. No complications were associated with ureteral detachment or resection. CONCLUSION: Our technique offers an alternative to the classic invagination technique by increasing transurethral traction on the ureteral stump, while substantially decreasing the risk of ureteral catheter dislodgment.

Humans↗
PubMed1996

Discordance of assay methods creates pitfalls for the interpretation of prostate-specific antigen values.

The availability of numerous different assays for the determination of prostate-specific antigen (PSA) has created substantial problems in the interpretation of PSA concentrations. Currently over 60 assays are commercially offered on the European market. The majority of the recently marketed assays are based on the commonly used reference range (< 4 ng/ml), although this rarely has been verified. Some manufacturers avoid specifying the range altogether, while others derive the data from very small collectives. Reference ranges established with sera of young males or even with an unspecified proportion of sera of females are not suitable for assessing the specificity of PSA assays for detecting prostate cancer among males older than age 50 years. Most manufacturers recommend that their assays not be used for diagnostic purposes but only for following up patients previously diagnosed with prostate cancer. Usually the physician remains unaware of this warning as well as of the name of the assay used. Since PSA concentrations may vary in identical samples by a factor of two depending on the assay used, the clinician in charge of interpreting the results needs to be aware of the method used and must have detailed information on the assay-specific reference range.

Humans↗
PubMed1995

Surgical management of renal cell cancer with extension into the vena cava: usefulness of intra-operative sonography.

Intracaval tumour extension represents a significant surgical problem in patients with renal cell carcinoma. Although pre-operative imaging techniques provide sufficient visualization for the planning of the majority of operative procedures, intra-operative ultrasound is nonetheless beneficial in some cases. In 3 patients, the procedure has given an accurate evaluation of the extent of the tumour thrombus. It has allowed safe placement of instruments which had lessened the risk of thrombus dislodgement. Intra-operative sonography is simple to perform and can be considered a valuable new adjunct in the evaluation and management of renal cell carcinoma with intracaval tumour extension. New technological advances may eventually improve the quality of intra-operative imaging.

Carcinoma, Renal Cell↗
PubMed1995

[Can the tumor stage of prostate carcinoma be determined with the aid of prostate-specific antigen?].

Prostate-specific antigen (PSA) is known to correlate with tumor grading, tumor volume, and lymph node and osseous metastases. If PSA concentrations exceed 20 ng/ml, the risk of extracapsular tumor extension increases greatly, and above 50 ng/ml organ-confined disease is extremely rare. Due to a considerable overlap in PSA concentrations between various tumor stages, the prediction of tumor stage with PSA alone is barely possible. In combination with other preoperative diagnostic findings, e.g. digital rectal examination or histological grade in multiple biopsies, the predictive value of PSA in terms of tumor stage determination can be increased to a large extent.

Biomarkers, Tumor↗
PubMed1995

[Different determination methods make interpretation of prostate-specific antigen more difficult].

The availability of numerous different assays for the determination of prostate-specific antigen (PSA) hs created substantial problems in the interpretation of PSA concentrations. Presently more than 40 assays are commercially promoted within the German market. The majority of the recently released assays claim the commonly used reference range (< 4 ng/ml) although this has no always been verified. Some companies entirely avoid the specification of reference ranges, others derive the data from very small cohorts. Reference ranges established with sera of young males or even with an unknown proportion of female sera are not valid in assessing the specificity of PSA assays to detect prostate cancer among male individuals between 50 and 80 years of age. Some companies recommend not to apply their assay for diagnostic purposes limit its use to the follow-up of patients previously diagnosed but to as having prostate cancer. This warning usually remains just as unknown to the urologist as the name of the assay used. Since PSA concentrations may vary in identical samples by a factor of 2, depending on the assay used, the clinician interpreting the results needs to be aware of the method applied and must have detailed information about the assay-specific reference range. Without this information, PSA loses its valuable diagnostic and prognostic features. Apart from avoidable worries on the patient's part, evidence of prostate cancer may be missed or unnecessary biopsies may be performed.

Aged↗
PubMed1995

Risk of bowel dysfunction with diarrhea after continent urinary diversion with ileal and ileocecal segments.

PURPOSE: In a retrospective study we evaluated the risk of diarrhea after continent urinary diversion using ileal and ileocecal segments. MATERIALS AND METHODS: We interviewed 100 patients of whom 65 underwent ileal and 35 underwent ileocecal resection. RESULTS: Of the 65 patients who underwent ileal resection 7 (11%) and of the 35 who underwent ileocecal resection 8 (23%) reported chronic diarrhea of greater than 6 months in duration, which subsided spontaneously in 2 patients in each group. In each group 3 patients responded well to cholestyramine treatment and 3 responded to loperamid or psyllium. Two patients with ileocecal resection failed to respond to drug therapy. CONCLUSIONS: The risk of diarrhea after ileocecal resection seems to be twice as high as after ileal resection. Most patients responded to symptomatic drug therapy. Alternative surgical therapies should be considered when risk factors are present.

Cecum↗
PubMed1994

Prostate-specific antigen corrected for prostate volume improves differentiation of benign prostatic hyperplasia and organ-confined prostatic cancer.

OBJECTIVE: To determine whether the ratio of PSA and prostate volume provides additional useful information for the discrimination of benign prostatic hyperplasia from prostatic carcinoma. PATIENTS AND METHODS: Since 1989, a prospective study has been in progress involving 229 patients (49 with locally confined prostatic carcinoma, 180 with benign prostatic hyperplasia) to establish whether the ratio of prostate-specific antigen (PSA) and prostate volume, determined by transrectal ultrasound (longitudinal x anterior-posterior x transverse diameter x 0.52), allows a better differentiation than the absolute PSA values. RESULTS: In this population of patients with prostatic disease, the positive predictive value for diagnosis of a prostatic carcinoma was 26% with an absolute PSA threshold value of 4.0 ng/ml, and 36% at a threshold value of 10 ng/ml. With a threshold value of the PSA/prostate volume ratio of 0.25 ng/(ml x cm3), the positive predictive value was 56% compared with 93% for a threshold value of 0.4 ng/(ml x cm3). CONCLUSION: The ratio PSA/prostate volume is a superior method for the diagnosis of prostatic carcinoma both with regard to its sensitivity and its specificity in patients with absolute PSA values in excess of 4 ng/ml.

Diagnosis, Differential↗
PubMed1994

Elimination kinetics of prostate-specific antigen serum and urine.

The serum half-life of prostate-specific antigen (PSA) was calculated in 66 patients subsequent to radical prostatectomy. Comparing serum half-life to disease outcome in 37 patients after a minimum follow-up of two years, it was found that PSA serum half-life identifies patients with residual disease earlier and more reliably than the presence or absence of detectable PSA levels postoperatively. It is suggested that residual tumor affects the half-life by contributing to the serum level of PSA. When PSA serum half-life was calculated solely in potentially cured patients, we found a half-life of 1.6 days, which is considerably shorter than in previous reports based on patient populations regardless of the outcome of disease in the follow-up. To elucidate the route of PSA elimination, serial urine PSA levels were determined before and after radical prostatectomy, revealing strong evidence for the assumption that PSA is not eliminated by the kidneys in its unchanged form.

Adenocarcinoma↗
PubMed1993

Prediction of tumor recurrence after radical prostatectomy using elimination kinetics of prostate-specific antigen.

The serum half-life of prostate-specific antigen (PSA) calculated subsequent to radical prostatectomy can serve to predict which patients are at high risk of bearing residual prostatic carcinoma despite their initial attainment of undetectable PSA serum levels. This report updates previous results to a mean follow-up period of 37 months. The initial results are essentially confirmed in that a mean PSA elimination half-life of 1.6 days in patients considered to be cured at least 24 months after prostatectomy provides additional useful information for predicting outcome in patients with potentially curable prostate cancer.

Adenocarcinoma↗
PubMed1993

[The quotient of prostate-specific antigen and prostate volume. Improved differentiation between benign prostatic hyperplasia and locally circumscribed prostate cancer].

Absolute serum prostate-specific antigen (PSA) values are of little help in the identification of locally confined prostatic cancer (PCA), because of a considerable overlap with the PSA values found in benign prostatic hyperplasia (BPH). Prostate gland volumes were estimated sonographically in 112 patients using the product of the three maximal diameters (longitudinal, anterior-posterior, transverse) and the factor 0.52. PSA was determined with a monoclonal immunoenzymetric assay (Tandem-E, Hybritech). The prostates were removed by either transvesical prostatectomy (for BPH) or radical retropubic prostatovesiculectomy (for PCA). In each case the diagnosis was verified by systematic histological examination. The ratio of serum PSA to estimated prostate volume did not exceed 0.4 ng/(ml x ml) in any of the 74 patients with BPH, whereas 23 of the 38 patients with PCA had a ratio above 0.4 ng/(ml x ml). The information provided by the PSA-prostate volume ratio is superior to absolute PSA values in preoperative differentiation between BPH and PCA. With a PSA-prostate volume ratio over 0.4 ng/(ml x ml) patients are at high risk for PCA and should be evaluated by prostate biopsy.

Adult↗