Biomedical subjects
Publications and source records attributed to Chester J Koh.
Advances have been made in every aspect of urology that strengthen the scientific underpinning of current urologic practices and that hopefully will encourage further scientific investigation into the source, mechanisms, and cure of urologic diseases. This article reviews some of the advances that have been detailed in the recent urologic literature.
PURPOSE: We compared urodynamic findings in patients who underwent prenatal closure of myelomeningocele with those of patients who underwent postnatal closure, and equivalent lower urinary tract evaluations. MATERIALS AND METHODS: Urodynamic studies of 5 patients (2 boys, 3 girls) who underwent prenatal closure of myelomeningocele were compared to those of 88 patients with similar level lesions who underwent repair postnatally between 1979 and 2002. RESULTS: All 5 patients in the prenatally treated cohort had lower lumbosacral lesions on neurological examination. These patients displayed no evidence of electromyographic activity, indicating complete denervation of the external sphincter. In comparison 34 of the 88 patients in the postnatal cohort (39%) lacked sphincter activity at newborn examination, with similar findings noted at 1-year evaluation. In terms of bladder function all 5 patients in the prenatal cohort exhibited detrusor overactivity, compared to 33 of the 88 patients (38%) in the postnatal cohort at the newborn examination, with similar findings at 1-year evaluation. CONCLUSIONS: Fetal closure of myelomeningocele is associated with a higher incidence of complete denervation of the external urethral sphincter and detrusor overactivity compared to postnatal closure. Patients who undergo this novel procedure should undergo urodynamic studies in the immediate newborn period and should be under close postnatal surveillance to document possible tethering of the spinal cord, urinary incontinence and increased detrusor pressures.
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The management of urethral foreign bodies may require the use of various surgical techniques in a urologist's armamentarium. We report a unique case of a urethral foreign body requiring percutaneous and endoscopic techniques for removal.
A severe shortage of donor organs available for transplantation in the United States leaves patients suffering from diseased and injured organs with few treatment options. Scientists in the field of tissue engineering apply the principles of cell transplantation, material science, and engineering to construct biological substitutes that will restore and maintain normal function in diseased and injured tissues. Therapeutic cloning, where the nucleus from a donor cell is transferred into an enucleated oocyte in order to extract pluripotent embryonic stem cells, offers a potentially limitless source of cells for tissue engineering applications. The present chapter reviews recent advances that have occurred in therapeutic cloning and tissue engineering and describes applications of these new technologies that may offer novel therapies for patients with end-stage organ failure.
OBJECTIVES: Male mice deficient in insulin-like 3 hormone (Insl3) or its receptor, Great/Lgr8, exhibit cryptorchidism. Recently, sequence analysis of the human INSL3 and GREAT genes identified several allelic variants. These include polymorphisms without apparent functional consequence and a few alleles encoding products with compromised function. However, loss-of-function alleles appear to be rare in human cryptorchidism. Most patients studied to date are presumed to have had sporadic cryptorchidism. We postulated that any genotypic variants predisposing to cryptorchidism would be more prevalent among patients with familial cryptorchidism. METHODS: We isolated genomic DNA from 13 individuals with personal and family histories of cryptorchidism and used polymerase chain reaction to amplify all exons of both INSL3 and GREAT, as well as INSL3 proximal promoter sequence, including a putative SF-1 transcription factor binding site. We directly sequenced all 20 amplicons and compared them with the wild-type alleles. RESULTS: We detected two silent substitutions and one missense (A60T) substitution in exon 1 of INSL3 and two silent substitutions in exon 12 and one missense (I604V) substitution in exon 17 of GREAT, all previously described. We found that in vitro the I604V GREAT variant receptor responds to INSL3 stimulation similarly to the wild-type receptor. CONCLUSIONS: We found polymorphic alleles of INSL3 and GREAT, but no deleterious mutations among individuals with familial cryptorchidism. Thus, mutations in these two genes are responsible only for a small proportion of familial cryptorchidism.
A severe shortage of donor organs available for transplantation in the United States leaves patients suffering from diseased and injured organs with few treatment options. Scientists in the field of tissue engineering apply the principles of cell transplantation, material science, and engineering to construct biological substitutes that will restore and maintain normal function in diseased and injured tissues. Therapeutic cloning, where the nucleus from a donor cell is transferred into an enucleated oocyte in order to extract pluripotent embryonic stem cells, offers a potentially limitless source of cells for tissue engineering applications. The present chapter reviews recent advances that have occurred in therapeutic cloning and tissue engineering and describes applications of these new technologies that may offer novel therapies for patients with end-stage organ failure.
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Few treatment options are available for patients suffering from diseased and injured organs because of a severe shortage of donor organs available for transplantation. Therapeutic cloning, where the nucleus from a donor cell is transferred into an enucleated oocyte in order to extract pluripotent embryonic stem cells, offers a potentially limitless source of cells for replacement therapy. Scientists in the field of tissue engineering apply the principles of cell transplantation, material science, and engineering to construct biological substitutes that will restore and maintain normal function in diseased and injured tissues. The present chapter reviews recent advances that have occurred in therapeutic cloning and tissue engineering and describes applications of these new technologies that may offer novel therapies for patients with end-stage organ failure.
Congenital abnormalities and acquired disorders can lead to organ damage or loss within the urinary tract. For reconstructive purposes, tissue engineering efforts are currently underway for virtually every type of tissue and organ within the urinary tract. Tissue engineering incorporates the fields of cell transplantation, materials science, and engineering for the purpose of creating functional replacement tissue, and requires personnel who have mastered the techniques of cell harvest, culture, expansion and transplantation, as well as polymer design. Major advances in the areas of stem cell biology, tissue engineering, and therapeutic cloning (nuclear transfer) techniques have made it possible to combine these technologies to create the comprehensive scientific field of regenerative medicine.