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Biomedical subjects

H P Koo

Publications and source records attributed to H P Koo.

17 recordsLinked to original sources
PubMed1998

Role of type III collagen in bladder filling.

The function of the urinary bladder is to store urine at low pressure and expel it periodically. To accomplish this, it must have the appropriate structural properties to accommodate slow but continuous volume changes. While much is presently known about the functional measurements of compliance, relatively little is known about the structural basis of compliance. In the present study, immunohistochemistry has been used to localize type III collagen fibers in the bladder wall at different intravesical volumes. To improve the resolution of these fibers, confocal microscopy was utilized to determine the changes in type III collagen fiber orientation and correlate them with the degree of mechanical distension of the bladder wall at partial and full capacity. We demonstrate that there were significant changes in both the orientation and conformation of type III collagen fibers during bladder filling. These observations support the view that volume accommodation in the bladder is achieved by changes in the arrangement of type III collagen. These data suggest that abnormal deposition or arrangement of type III collagen fibers can have an impact on normal bladder function.

Animals↗
PubMed1998

Comments on pediatric elimination dysfunctions: the Whorf hypothesis, the elimination interview, the guarding reflex and nocturnal enuresis.

AIMS OF STUDY: This paper addresses pediatric elimination disorders including nocturnal enuresis from the perspectives of terminology (the Whorf hypothesis), the elimination interview, and the guarding reflex. METHODS: The elimination interview and a modern model of normal voiding function, including the guarding reflex, are explained. RESULTS: The language of voiding dysfunction influences our perception of it. Nocturnal enuresis, and all other voiding dysfunctions, should be evaluated by a careful elimination interview. The guarding reflex may fit into an evolving etiologic paradigm for nocturnal enuresis. CONCLUSIONS: (1) Words and phrases of eliminology should aim for simplicity, clarity and accuracy. (2) Urologists need to perfect their eliminology skills vis-à-vis the elimination interview. (3) The role of the guarding reflex in nocturnal enuresis and all other voiding dysfunctions should be critically examined.

Arousal↗
PubMed1998

Laparoscopy for the nonpalpable testis.

Cryptorchidism represents one of the most common childhood disorders with the incidence of testicular maldescent being 0.8% by 1 year of age. Nonpalpable testis occurs in approximately 20% of patients with cryptorchidism. Laparoscopy for diagnosis and management of nonpalpable testis has shown to be highly effective with few complications. This article reviews some of the special considerations in performing laparoscopy in children with descriptions about the unique features of a child's anatomy and physiology. The role of laparoscopy in the evaluation and management of nonpalpable testis is discussed, along with some of the controversies about how laparoscopy may be changing our approach to a child with a nonpalpable testis.

Cryptorchidism↗
PubMed1998

Temporal expression of elastic fiber components in bladder development.

Fetal and postnatal bovine bladders were examined for expression of elastic fiber components by immunohistochemistry as well as by measurement of steady state mRNA levels. Expression of fibrillin-1, microfibril-associated glycoprotein (MAGP) and elastin during the fetal period were compared with that of postnatal two year old animals (heifers) and adults. Each bladder was separated into two distinct tissue samples: 1) the outer smooth muscle layer (detrusor) and 2) the inner epithelium (urothelium) lined lamina propria (urotherial-lamina propria). Each of these samples was analyzed separately. Distribution of the elastic fiber components, determined by immunohistochemistry with matrix-specific antibodies, was different depending upon the region of the bladder wall examined and its developmental stage. In particular, MAGP and fibrillin-1 were conspicuously present in the urothelium during the later fetal stages. RNA products of elastic fiber genes were detectable both in the detrusor smooth muscle and urothelial-lamina propria fractions. The highest level of expression occurred in the urothelial-lamina propria fraction during the late second-early third trimester. Elastin expression was different from that of MAGP and fibrillin-1. The highest levels of steady-state elastin mRNA occurred at the earliest developmental stages examined and then progressively decreased through term. A high level of elastin expression occurred within the inner or lamina propria layer of the bladder. Since this layer is the functional capacitance layer within the bladder, its flexibility is likely related to the structural integration of elastin and associated microfibrillar components.

Animals↗
PubMed1997

Developmental expression of interstitial collagen genes in fetal bladders.

Bovine bladders at 3 stages during fetal development were examined for expression of collagens by immunohistochemistry as well as by measurement of steady state mRNA levels. Expression of type I and type III collagens during the fetal period was compared with that of adult cows as well as a young animal (heifer). Each bladder was separated into a detrusor and a urothelial-lamina propria sample which were then analyzed separately. Distribution and fiber arrangement of types I and III collagens were different depending upon the region of the bladder wall examined. Type III collagen, in particular, has a "coiled" appearance which is especially prominent within the lamina propria. Collagen gene expression showed a distinctive pattern which was different for both type I and type III collagen. While type I collagen gene expression peaked during the late second to early third trimester, type III collagen expression progressively decreased throughout the fetal period. In addition, expression of both collagens was greater in the urothelial-lamina propria fractions. These data demonstrate that the pattern of collagen gene expression in the developing bladder is developmentally regulated and is unique to each of the two major structural layers.

Animals↗
PubMed1996

The long-term outcome in men with exstrophy/epispadias: sexual function and social integration.

PURPOSE: We evaluated the long-term outcome of social integration and sexual function in 29 men with bladder exstrophy and epispadias. MATERIALS AND METHODS: Four men with epispadias and 25 with bladder exstrophy were available for long-term followup. Patients were interviewed by telephone regarding sexual history and social integration. Semen analyses were obtained in 8 cases. RESULTS: Patient assessment of genital appearance was good or fair in 71%. Potency was present in all patients, and erections were straight in 66% and curved in 34% with no curvature so severe as to prevent sexual intercourse. Semen analysis showed a normal sperm count in 63% of the men and no azoospermia. Social integration was satisfactory: 100% of the men attended high school, 55% have a college education and all who are not attending school have full-time jobs. CONCLUSIONS: Our long-term review demonstrates that despite what appears to be a significant sexual handicap, patients with exstrophy/epispadias can have adequate sexual function and overall successful social integration.

Bladder Exstrophy↗
PubMed1996

Long-term results of ureterosigmoidostomy in children with bladder exstrophy.

PURPOSE: We evaluated long-term results of patients with bladder exstrophy who underwent ureterosigmoidostomy. MATERIALS AND METHODS: Of 4 women and 23 men monitored at our institution 16 (59%) underwent primary diversion by ureterosigmoidostomy, while 11 (41%) underwent primary bladder closure or an ileal conduit procedure before conversion to ureterosigmoidostomy. Average followup after ureterosigmoidostomy was 17 years. RESULTS: Significant upper urinary tract changes developed in 18% of the patients. Metabolic acidosis was well compensated in most patients but 2 had problems with urinary retention leading to hyperammonemia and acidosis. Of the 19 patients monitored with biennial colonoscopy benign polyps were removed in 4. Daytime continence was achieved in 92% of cases and nighttime continence in 58%. CONCLUSIONS: Our experience with ureterosigmoidostomy in children with bladder exstrophy has been favorable through long-term followup. With proper imaging, metabolic surveillance, biennial colonoscopy and nonsteroidal anti-inflammatory drugs we offer ureterosigmoidostomy as a viable alternative for patients with small bladders.

Bladder Exstrophy↗
PubMed1995

The ontogeny of bladder function in the fetal calf.

Although numerous experimental studies have addressed urinary bladder physiology and pharmacology, little information is available concerning the ontogeny of bladder function. The present in vitro study describes the developmental aspects of bladder compliance, pressure generation and emptying in bovine fetuses from early second trimester to term (280 days). The results can be summarized as follows: 1) bladder compliance increased 3-fold between early second trimester and term; 2) sustained contractile response to bethanechol was present in all bladders; 3) field stimulation produced a submaximal, nonsustained contraction and an active relaxation when the field stimulus was turned off; 4) bladder emptying in response to bethanechol was nearly 100% in mid- and late-gestational bladders but was only 50% at early gestation; 5) bladder emptying in response to field stimulation was 20% to 40% for all gestational age groups; 6) field stimulated relaxation was observed only in the fetal bladder. These studies demonstrate that bladder physiology in utero is different from postnatal bladder function. The presence of a relaxant response during the fetal period may reflect a unique and significant role of the in utero bladder in protecting the upper urinary tracts from sustained increased pressure.

Adenosine Triphosphate↗
PubMed1994

Neurotrophic factors in the rat penis.

An intact nerve supply is essential for normal erectile function. We have undertaken a study to examine the presence and synthesis of growth factors of the penis that support neural function. Extracts were obtained from deskinned penises of Sprague-Dawley rats, aged 3, 6 and 10 weeks, representing prepubertal, pubertal and postpubertal states. Penile extracts were subjected to Northern blot analysis to evaluate expression of nerve growth factor-beta (beta-NGF)-mRNA, PC-12 bioassay to quantitate the nerve growth promoting activity and immunoassay to detect the amount of beta-NGF protein. These initial experiments showed a disproportionately abundant level of nerve growth promoting activity as compared with the levels detected with the immunoassay. The PC-12 bioassay is sensitive to both beta-NGF and fibroblast growth factors (FGFs). To further investigate these findings, the bioassay was conducted again after heparin chromatography, with beta-NGF receptor blockade, or with the addition of anti-beta-NGF, anti-basic-FGF, or anti-acidic-FGF. These studies confirmed that the abundant nerve growth promoting activity in the rat penis is due largely to basic FGF. In conclusion, the neurotrophin NGF is expressed in the rat penis at levels consistent with its expression in other peripheral tissues. Basic-FGF, on the other hand, has been detected at levels far in excess of NGF. Since erectile function is dependent on the integrity of the vascular structure and its intact innervation and since basic FGF presents as an abundant penile growth factor with both angiogenic and neurotrophic activities, basic FGF might play a significant role in erectile physiology.

Animals↗
PubMed1993

Early molecular changes associated with streptozotocin-induced diabetic bladder hypertrophy in the rat.

We describe early alterations in rat bladder gene expression which may relate to the development of diabetic bladder dysfunction in a streptozotocin model of inducible diabetes. Utilizing cDNA probes, the gene products sulfated glycoprotein-2 (SGP-2), transforming growth factor-beta (TGF-beta), beta-actin (beta-actin), N-ras and beta nerve growth factor (beta-NGF), were quantitated in bladders of male Sprague-Dawley rats at 1, 2, 4 and 6 weeks after induction of diabetes with streptozotocin (STZ). beta-actin and SGP-2 expression were transiently increased at 1 and 4 weeks after induction, respectively. TGF-beta was not altered over the period of the study. N-ras was reduced at all times compared with control rat bladders. Transcripts encoding beta-NGF were dramatically increased in STZ-treated rats at 4 weeks. None of these changes were seen in diuresis control group fed 5% sucrose. Our results suggest that during the early stages of diabetes, cellular hypertrophy, growth and remodeling are occurring concomitantly with cellular injury and programmed cell death. Furthermore, the transient increase in expression of beta-NGF mRNA may represent a compensatory response to the diabetic condition in an attempt to attract further innervation and revascularization.

Actins↗
PubMed1993

Molecular biology of Wilms' tumor.

This article reviews recent advances in the molecular biology in cytogenetics of Wilms' tumor. The role of tumor suppressor genes in the development of tumors is reviewed and the mapping and genetic loci associated with Wilms' tumor is elucidated. The identification of the WT1 gene as well as the normal expression of that gene is reviewed. Identification of the putative WT2 gene is also reviewed.

Child↗
PubMed1992

Age at last birth and its components.

This paper examines the ways in which the behavior of twentieth century cohorts of American women changed simultaneously in the three components of fertility that determine age at last birth--age at first birth, spacing between subsequent births, and parity progression ratios of subsequent births--to produce changes in the timing of the completion of childbearing. It decomposes changes in the mean age at last birth among cohorts and between whites and nonwhites to changes in these three components. To perform these analyses, we developed and applied a method to estimate the distributions and means of ages and last births, birth intervals, and parity progression ratios from age- and parity-specific fertility rates available from vital statistics data. Results show that the cohorts increased and decreased their age at first birth, birth intervals, and parity progression ratios of lower and higher birth orders in almost every possible combination so as to achieve a relatively young age at final birth.

Birth Intervals↗
PubMed1983

Interrelationships between fertility and marital dissolution: results of a simultaneous logit model.

Previous studies have failed to examine (a) the simultaneity of decisions to bear children and to dissolve a marriage and (b) the effects of the childbearing in the period just before dissolution on the likelihood of disruption. We attempted to resolve both problems by developing a simultaneous logit model of the interrelationship between the probability of separation and of having a birth during this period (when dissolution presumably is being considered). The model was estimated at successive durations of first marriage, using data for white women in the 1970 National Fertility Survey. The results indicate that childbearing patterns--number of children and age of youngest child at the beginning of the marital interval being studied and fertility during the interval--did not influence the likelihood of separation in simple or consistent ways over the marital life course, nor did marital strife (as indicated by separation) seem to affect childbearing throughout marriage.

Decision Making↗