Biomedical subjects

J G Moreno

Publications and source records attributed to J G Moreno.

14 recordsLinked to original sources

PubMed1998

Utilization of polymerase chain reaction technology in the detection of solid tumors.

BACKGROUND: Most cancer detection tests currently performed are based on either antibody assays to a marker protein with altered expression in cancer patients or on imaging studies to identify characteristic lesions. Generally, for a positive result, these detection assays require that a tumor have a significant volume of cancer cells. Advances in diagnostic techniques and technology may allow for cancer detection at earlier stages, when the tumor burden is smaller and potentially more curable. The molecular techniques of polymerase chain reaction (PCR) and reverse transcriptase PCR (RT-PCR) are highly sensitive methods for detecting a small number of cancer cells. Over the past few years, numerous clinical studies have used PCR techniques to detect physical alterations of genes, such as mutations, deletions, translocations and amplification, the presence of oncogenic viruses, and the expression of genes specific to tissue, cancer, and metastasis. The current status of PCR as a method for detecting marker genes in the management of solid tumors is reviewed. METHODS: A review of the literature on the clinical utility of PCR and RT-PCR in the detection of solid tumor micrometastasis was conducted. RESULTS: Amplification by PCR is a highly sensitive method to determine gene expression. A single cell expressing a tumor marker among 10-100 million lymphocytes can be detected by the PCR assay. This approach has been used to detect tumor cells in approximately 18 different solid tumor types, with melanoma and carcinoma of the breast and prostate the most widely investigated to date. PCR-based assays have been used to detect cancer cells in biopsies of solid tissue, lymph nodes, bone marrow, peripheral blood, and other body fluids. Several studies have reported a high specificity and sensitivity of tumor marker detection and a high correlation between PCR results and the presence of metastatic disease. However, in a few studies, PCR assays have not consistently demonstrated a higher sensitivity and specificity of detection than traditional modalities for many types of cancer. There has been a wide range in sensitivity and specificity among the studies, which may be partly attributed to the lack of uniformity among the PCR protocols used in different studies. CONCLUSIONS: PCR can detect tumor marker-expressing cells that are otherwise undetectable by other means in patients with localized or metastatic cancer. Reports from various study groups have lacked uniformity in their protocols, and this has prevented adequate comparison. The clinical utility of this assay as a tool for the prognosis and management of cancer patients remains and area of active investigation. PCR is a powerful tool in the study of the biology of cancer metastasis and will likely serve as a useful adjunct to clinical decision-making in the future.

Biomarkers, Tumor↗

PubMed1997

Transrectal ultrasound-guided biopsy causes hematogenous dissemination of prostate cells as determined by RT-PCR.

OBJECTIVES: To determine if transrectal ultrasound-guided (TRUS) prostate biopsy causes dissemination of prostate cells into the circulation as assessed by reverse transcriptase-polymerase chain reaction (RT-PCR) targeted against prostate-specific antigen (PSA) mRNA. METHODS: RT-PCR PSA analysis was performed before and after prostatic invasive manipulations in 50 men. The cases consisted of 47 patients with TRUS and 3 with transurethral resection of the prostate (TURP). Peripheral venous blood (8 mL) was drawn before and within 60 minutes after the procedure. Total RNA was extracted from fractionated blood, and RNA/cDNA quality was assured and normalized with beta-actin RT-PCR analysis. The PSA primers hybridize exons 3 and 5, yielding a 254-basepair PCR product. The assay detects one LNCaP cell in a background of 100 million lymphoid cells and a single copy of PSA cDNA on an ethidium bromide gel. RESULTS: Among the 47 TRUS cases, 43 specimens were evaluable. Forty-two cases were negative before biopsy; among these patients, 4 cases (9.5%) converted to a positive RT-PCR PSA result. Both benign and malignant TRUS biopsies were capable of producing a positive RT-PCR PSA signal implicating iatrogenic dissemination of cells. All three TURP cases converted from a negative to a highly intense positive signal. CONCLUSIONS: We conclude that a positive RT-PCR PSA signal may result from release of prostate cells into the peripheral circulation after a TRUS biopsy and TURP. TURP causes greater dissemination than TRUS. Based on these preliminary data, we recommend that future molecular staging studies should be based on blood specimens drawn before performance of TRUS biopsy. This may be an important mechanism of prostate cancer dissemination meriting further investigations.

Aged↗

PubMed1997

Reverse transcriptase polymerase chain reaction for prostate specific antigen in the management of prostate cancer.

PURPOSE: Polymerase chain reaction is a powerful tool for expanding minute quantities of deoxyribonucleic acid (DNA) for detailed study. Reverse transcriptase polymerase chain reaction (RT-PCR) involves the initial conversion of messenger ribonucleic acid (mRNA) to DNA, followed by the amplification of the DNA product for molecular analysis. The mRNA for prostate specific antigen (PSA) is expressed only by prostatic cells. RT-PCR offers a potentially more sensitive assay for the detection of cells expressing PSA mRNA in peripheral circulation or in extraprostatic tissues. The current status of RT-PCR in the amplification and detection of PSA gene expression in the management of prostate cancer is reviewed. MATERIALS AND METHODS: The literature was reviewed for available data using RT-PCR for detection of prostatic cells outside of the prostate. RESULTS: Amplification of mRNA by RT-PCR represents a highly sensitive method of detection of gene expression. A single cell expressing PSA among 10 to 100 million lymphocytes can be detected by the RT-PCR assay. This assay may detect extraprostatic or circulating prostatic cells in peripheral blood, lymph nodes and bone marrow in many patients with prostate cancer. Various studies have reported sensitivities of detection of PSA expressing cells in the peripheral blood ranging from 0 to 88%. This wide range in the sensitivity may be partly due to tremendous variation between the protocols used in each study. In patients with lymph node metastasis the RT-PCR assay appears more reliable than immunohistochemistry for identification of prostatic tissue in the lymph node. In some series analyses of radical prostatectomy specimens suggest a strong correlation between a positive RT-PCR result and capsular invasion by the tumor, while others do not support its use in determining pathological stage. In the majority of reports the RT-PCR assay was highly specific for detection of extraprostatic PSA expression in prostate cancer patients, and negative for detection in men with benign prostatic hyperplasia and in women. Sources of potential false-positive and false-negative results of this assay are identified and discussed. CONCLUSIONS: RT-PCR can detect PSA expressing cells that are otherwise undetectable by other means in patients with localized and metastatic cancers. This assay is highly specific, since PSA expressing cells were consistently undetectable in the peripheral circulation of patients without prostate cancer in most studies. Limited data to date suggest that this test may have a role in the staging of tumors before radical prostatectomy and in the serial followup of patients after treatment. RT-PCR may improve the detectability of lymph node metastasis over immunohistochemistry. Presently this test should remain a powerful research tool in the study of the biology and behavior of prostate cancer, and it should not be used to guide any clinical decision making. The use of this assay as a prognostic and management tool for prostate cancer is in the earliest stages.

Clinical Trials as Topic↗

PubMed1996

A comparative analysis of prostate-specific antigen gene sequence in benign and malignant prostate tissue.

OBJECTIVES: Different molecular forms of prostate-specific antigen (PSA) appear to be expressed by benign prostatic hyperplasia (BPH) compared with prostate cancer. These differences are not well understood and may arise from aberrant RNA splicing, altered protein glycosylation, or variant PSA complexing to macroglobulins. To our knowledge, a direct comparison of PSA mRNA sequences in BPH versus prostate cancer to account for these differences has not been reported. The purpose of this study was to compare the complete PSA mRNA gene sequences in benign and malignant prostate tissue to determine whether altered PSA phenotypes are a result of gene mutations and to compare the published PSA sequences. METHODS: Total RNA was extracted from 17 prostate specimens from 8 patients, including matched benign and malignant prostate tissue in 6 patients. The samples were subjected to reverse transcriptase-polymerase chain reaction (RT-PCR) of the PSA coding sequence and part of the 3' untranslated region. Directed DNA sequencing was performed on these fragments. RESULTS: The benign and malignant prostate tissue cDNA sequence data of both strands were aligned and a computer analysis revealed 100% match with no evidence of mutation in prostate cancer compared to normal tissue. Sequence analysis did not reveal point mutations or aberrant splicing in any of the samples, including the matched malignant and nonmalignant tissues. Comparison with published sequences revealed infrequent and inconsistent sequence differences. CONCLUSIONS: These findings suggest that the PSA gene expressed in malignant prostate tissue is the wild type. PSA structural alterations previously reported in the literature may occur through post-transitional mechanisms. A detailed understanding of the possible differences in the PSA gene sequence is essential as we develop newer techniques that utilize RT-PCR to perform molecular diagnosis and staging of prostate cancer.

Base Sequence↗

PubMed1996

Analysis of tumor spillage during radical prostatectomy using RT-PCR of prostate specific antigen.

Recent reports have suggested the shedding of cancer cells during radical extirpation of tumors. Prostate cells can be expressed from the prostate ex vivo and found in the expressed prostatic secretions. We conducted an in vivo study to determine if prostate epithelial cells can be found in the operative site as determined by RT-PCR targeted at prostate specific antigen (PSA) and to correlate this with pathologic stage and outcome. We analyzed 14 consecutive radical retropubic prostatectomy procedures with a minimum 1-year follow-up. Intraoperatively, 5-10 ml of fluid (representing blood, urine, and irrigant) was aspirated from the operative field at three time points: after transaction of the dorsal vein complex, urethra, and bladder neck. Ficoll gradient fractionation was carried out on the specimens, and RNA was extracted from the cell pellet. Quality of RNA and presence of the PSA mRNA was determined by RT-PCR targeted at actin and PSA, respectively, using previously published primers. The medical records were reviewed for pathologic stage. There were nine patients with extraprostatic disease and five patients with organ confined disease. Five of 14 (36%) patients tested positive for prostate epithelial cells in the operative field at one or more points during radical prostatectomy. All five positive RT-PCR PSA assays were in patients with locally advanced disease, whereas all of the patients with organ-confined disease were negative for RT-PCR. This preliminary in vivo study suggests that locally advanced prostate cancer may be associated with PSA expressing cells in the operative field during radical prostatectomy. The clinical significance of this is unclear, but this finding suggests that shedding of cells in the operative field is more likely with locally advanced disease.

Combined Modality Therapy↗

PubMed1995

Improved quality of life and sexuality with continent urinary diversion in quadriplegic women with umbilical stoma.

Quality of life issues prompted us to offer continent urinary diversion to quadriplegic women who required cystectomy for end-stage neurogenic vesical dysfunction complicated by urethral destruction as a result of chronic indwelling catheterization. Three women with spinal cord injury (SCI) and resultant quadriplegia of 5 to 15 years duration underwent continent urinary diversion. Preoperative evaluation and urodynamic studies in each showed a bladder capacity of less than 150mL, bilateral vesicoureteral reflux, recurrent febrile urinary tract infections, an incompetent urethral sphincter, and incontinence around an indwelling catheter in all three patients. Although highly motivated, these women showed minimal dexterity and were unable to perform urethral self-catheterization. Each was opposed to having an incontinent abdominal urinary stoma. The urinary reservoir was created from 30cm of detubularized right colon. The continence mechanism used an intussuscepted and imbricated ileocecal valve. The umbilicus was chosen as the urostomy site because of cosmetic appearance and ease of catheterization for a patient with minimal dexterity. Follow-up ranged from 18 to 30 months. Reservoir capacity ranged from 550 to 800mL without evidence of reflux or stomal leakage. The incidence of symptomatic autonomic dysreflexia and urinary tract infection decreased postoperatively in all patients. Of the two women who were sexually active, the frequency of activity increased from 8 to 15 episodes per month in one and 3 to 4 episodes per month in the other. Both reported improved sexual enjoyment. Body image and satisfaction with urologic management increased in all three patients. In conclusion, continent urinary diversion in selected quadriplegic patients is a reasonable alterative to incontinent intestinal urinary diversion. The umbilical stoma provides an excellent cosmetic result which patients with minimal dexterity are able to catheterize easily. Continent urinary diversion in women results in improved self-image, quality of life, and enables greater sexual satisfaction.

Adult↗

PubMed1995

Noninsufflative laparoscopic access.

Standard laparoscopic surgery requires maintenance of the working cavity by continual carbon dioxide insufflation and exaggerated Trendelenburg positioning. Both cardiopulmonary and metabolic adverse effects may result from these maneuvers, which may be avoided by a gasless approach to laparoscopic surgery. We investigated a new mechanical retraction system designed to maintain exposure of either intraperitoneal or retroperitoneal contents in a gasless laparoscopic cavity and assessed its performance in both laparoscopic approaches. Gasless laparoscopic surgery was attempted using the Laprolift/Laparofan system for retroperitoneal procedures: left varicocele ligation (three cases), renal biopsy (one case), extraperitoneal pelvic lymph node dissection (one case), and intraperitoneal bilateral varicocelectomy (two cases). Renal biopsy and varicocelectomy were accomplished successfully with the gasless approach and with technical ease comparable to that of the standard insufflative laparoscopic approach. Gasless pelvic lymph node dissection and intraperitoneal varicocelectomy were converted to insufflative laparoscopic or open procedures because of inadequate exposure of the pelvic contents. This early experience with gasless laparoscopy indicates that it may best be reserved for retroperitoneal urologic procedures.

Biomechanical Phenomena↗

PubMed1995

New prostatectomy technique: transurethral electrovaporization of the prostate.

Major health and economic concerns have caused urologists to seek alternative forms of treatment for benign prostatic hypertrophy (BPH). The goal of these newer treatments is to decrease morbidity, reduce health care cost, and improve overall outcome for the patients with symptomatic bladder outlet obstruction. Transurethral resection of the prostate (TURP) is the gold standard treatment for BPH. One factor associated with the relative higher cost of a TURP is the average 4-day postoperative stay needed to clear the hematuria. Techniques have evolved that have allowed immediate tissue removal through "vaporization" of the prostate with a decrease in the postoperative stay. These techniques have primarily relied upon the use of lasers to vaporize tissue. A new transurethral prostatectomy technique called transurethral electrovaporization of the prostate (TVP) has been recently introduced. This relies upon a newly developed resectoscope electrode (VaporTrode) that allows vaporization of the prostate tissue in the "cutting" mode. The potential advantage of TVP is the reduction in postoperative hematuria and the utilization of equipment and techniques that are already familiar to the practicing urologist.

Aged↗

PubMed1994

Late complications of the modified Indiana pouch.

The modified Indiana pouch is currently an accepted and widely used form of continent cutaneous urinary diversion. However, results of long-term followup and potential late complications are still being established. We report our experience with 130 modified Indiana pouches performed between September 1987 and September 30, 1991. In 16 patients (12%) late complications developed between 1 and 16 months after the pouch procedure. Ureteral obstruction developed in 9 of these patients (7%), including bilateral obstruction in 4. Balloon dilation with or without incision of ureteral strictures in 6 patients resulted in an 83% failure rate, while ureteral reimplantation was successful in 91% (10 of 11 cases). Reservoir dysfunction was the late complication in the remaining 7 patients. Urodynamic evaluation was essential in determining appropriate treatment for incontinence with either replication of the ileal segment or pouch augmentation with an ileal patch. Of the 16 late complications 56% occurred in patients who received between 3,000 and 6,500 rad of pelvic radiation before the urinary diversion. We conclude that the modified Indiana pouch is a successful form of urinary diversion with an acceptable complication rate. Ureteral balloon dilation with or without endoscopic incision of ureteral strictures has not been successful. However, patients can usually undergo successful ureteral reimplantation via an extraperitoneal approach with minimal morbidity. Previously radiated patients are at higher risk for complications and require shorter ureteral tunnels to avoid stricture, in addition to an ileal patch at initial construction.

Adult↗

PubMed1994

Controlled balloon dilatation of the extraperitoneal space for laparoscopic urologic surgery.

Laparoscopic urologic surgery has become increasingly more popular, with the majority of procedures and techniques that have been described based on intraperitoneal experience and anatomic considerations. Urologic surgery, traditionally confined mostly to the extraperitoneal space, has followed these intraperitoneal descriptions when undertaken laparoscopically. Our experience of controlled, laparoscopically monitored dilatation of the extraperitoneal space using a new trocar-mounted balloon dissector can create a working space in a surgical environment familiar to traditional open urologic surgery. We report our initial experience with the preperitoneal distention balloon in 15 patients, emphasizing the technique of extraperitoneal access and the laparoscopic visualization of anatomy relevant to pelvic lymph node dissection, varicocele ligation, nephropexy, and renal biopsy. In this early experience, laparoscopic pelvic lymph node dissection was performed successfully in 7 of 11 patients and in all other patients undergoing the retroperitoneal procedures. Patients with a prior history of hernia repair or appendectomy do not appear to be suitable to this approach when used for pelvic lymphadenectomy. The trocar-mounted balloon device allows direct visualization and control of the dissection process. Avoiding the transperitoneal approach may eliminate many of the complications associated with the transperitoneal access and procedure completion. We conclude that the extraperitoneal technique using this device merits further investigation and more widespread application in the laparoscopic approach to conventional extraperitoneal urologic procedures.

Biopsy↗

PubMed1993

Serologic response to Helicobacter pylori among children and teenagers in northern Chile.

The serologic response to Helicobacter pylori was determined in 388 children and teenagers living in Iquique, Chile by using an IgG enzyme-linked immunosorbent assay. Serum antibody levels, as measured by optical density, correlated strongly with age. Increases in the mean antibody level were seen primarily after age five, with rates of seropositivity increasing to > or = 70% among teenagers. The reasons for this age-related pattern of acquisition of infection remain to be determined.

Adolescent↗

PubMed1992

Detection of hematogenous micrometastasis in patients with prostate cancer.

The goal of this study was to determine if patients with stage D0-3 prostatic adenocarcinoma have detectable hematogenous micrometastasis. Polymerase chain reaction amplification of prostate-specific antigen mRNA, which is exclusively expressed by prostatic epithelial cells, was used to detect circulating prostatic cells. Peripheral venous blood was obtained from 17 control and 12 prostate cancer patients with stage D0-3 prostatic adenocarcinoma. Of the 12 cancer cases, four patients (stage D1-3) tested positive for prostate-specific antigen RNA, indicating the presence of circulating micrometastasis. The 17 negative controls all tested negative. Contrary to a long held hypothesis, these data point to the possibility that hematogenous metastasis may be a relatively early event in the natural history of human prostate cancer. These findings may have an important impact on our understanding and treatment of prostate cancer.

Base Sequence↗

PubMed1992

Late local complications after definitive radiotherapy for prostatic adenocarcinoma.

Definitive radiation treatment of prostatic adenocarcinoma has been reported to produce good long-term local disease control, and distant disease failure is almost always associated with good local palliation. We examined late local complications in patients who died with recurrent prostate cancer after definitive radiotherapy as compared to patients treated with hormonal deprivation alone for advanced disease. Between 1979 and 1989 the tumor registry listed 33 men in whom definitive radiotherapy failed documented by bone scan or biopsy and 54 men who were managed with palliative hormonal therapy for noncurable disease. A complication was defined as a local problem requiring a procedure or hospitalization. Overall 23 of the radiotherapy cases (70%) had a local complication as compared to 16 of the patients (30%) who underwent only hormonal therapy. Local complications after radiotherapy included urethral stricture (10 cases), prostatic obstruction (8), hematuria (4), radiation cystitis (3), ureteral obstruction (2) and rectosigmoid radiation injury (4). Local complications after hormonal therapy consisted of prostatic obstruction (11 cases), ureteral obstruction (3) and hematuria (3). The radiotherapy group had 2 urinary and 2 fecal diversions, and the hormonal therapy group had none. In summary, we found a higher risk of late local complications in patients who had recurrence and died with metastatic prostate cancer after definitive radiotherapy, as compared to patients who only received hormonal therapy. These results question the belief that patients with distant disease in whom radiotherapy fails enjoy good long-term local palliation.

Adenocarcinoma↗

PubMed1992

Reversal of the malignant phenotype by an anti-ras ribozyme.

In this study a ribozyme (catalytic RNA) was designed to site specifically cleave the mRNA of the activated H-ras gene expressed in human bladder carcinoma EJ cells. The optimal conditions for catalytic cleavage by the ribozyme were demonstrated in vitro. A synthetic DNA encoding the ribozyme was cloned into a mammalian expression vector (pH beta APr-1) and transfected into EJ cells. The expressed ribozyme significantly altered the morphology and suppressed the growth of EJ cells in vitro. These cell lines were examined for their malignant potential in athymic (nude) mice by an orthotopic (transurethral) implantation model, which recapitulates the invasive potential of various bladder carcinomas. EJ tumors expressing the H-ras ribozyme were characterized by a marked reduction in tumor take and invasion compared to those formed by control EJ cells. These differences resulted in almost a twofold increase in survival of mice implanted with ribozyme-containing EJ cells. These results further elucidate the role of ras genes in tumorigenicity and invasion, as well as introduce ribozymes as a new class of anticancer agents.

Animals↗