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Stephen A Zderic

Publications and source records attributed to Stephen A Zderic.

31 records · Page 2Linked to original sources
PubMed2004

Over expression of smooth muscle specific caldesmon by transfection and intermittent agonist induced contraction alters cellular morphology and restores differentiated smooth muscle phenotype.

PURPOSE: The thin filament associated protein h-caldesmon (h-CaD) modulates actin myosin interaction and contraction. Bladder outlet obstruction and detrusor hypertrophy are associated with the over expression of the nonmuscle CaD isoform l-CaD. It implies a poorly differentiated state of bladder myocytes and cytoskeletal remodeling in detrusor hypertrophy. We determined if h-CaD expression can be increased in a unique bladder smooth muscle (BSM) cell line derived from obstructed rabbit bladder smooth muscle that over expresses l-CaD. We examined whether the genetic restoration of h-caldesmon is possible in bladder smooth muscle cells by transfection or by agonist mediated contraction and whether this manipulation would alter cellular morphology. MATERIALS AND METHODS: BSM cells were transfected with chicken h-CaD cDNA inserted into a mammalian vector. In another experiment BSM cells underwent intermittent bethanechol induced stimulation. h-CaD mRNA and protein were quantified with reverse transcriptase-polymerase chain reaction and Western blot analyses. Cell morphology was assessed using phase, video and confocal microscopy after double immunostaining with antibodies against alpha-actin and caldesmon. RESULTS: Reverse transcriptase-polymerase chain reaction using primers specific for the transfected vector and h-CaD cDNA confirmed stable transfection of cells and increased content of h-CaD mRNA. Following bethanechol induced intermittent contraction Western blotting revealed 80% relative over expression of h-CaD in treated transfected cell lines (p <0.05) and 74% (not significant) in treated nontransfected controls. Confocal immunofluorescence microscopy revealed CaD in the cytoplasmic filaments co-localized to alpha-actin in the main cell body and perinuclear region in transfected cells, in contrast to the diffuse, irregular distribution of these filaments in control cells. CONCLUSIONS: A unique bladder myocyte cell line was successfully and stably transfected with h-CaD cDNA. We show that agonist induced intermittent contraction preferentially increases h-CaD expression, the predominant CaD in nonobstructed bladder smooth muscle, and the restoration of h-CaD alters cell morphology and the organization of cytoplasmic filaments in cells derived from obstructed rabbit detrusor musculature.

Bethanechol↗
PubMed2004

A male murine model of partial bladder outlet obstruction reveals changes in detrusor morphology, contractility and Myosin isoform expression.

PURPOSE: Mice with gene deletion or targeted over expression are important for understanding the remodeling that follows partial bladder outlet obstruction (PBOO). This condition predominates in males. We produced PBOO in male mice and now report the physiological, histological and molecular consequences. MATERIALS AND METHODS: Male C57bl/6 mice were surgically obstructed or subjected to sham surgery and unoperated mice served as controls. Four weeks later the bladders were excised and their function was assessed with in vitro whole bladder cystometry. The optimum volume for pressure generation was determined and isometric pressures were measured for field stimulation and depolarization with KCl. Bladder hypertrophy was classified as severe-bladder mass greater than 50 mg or mild-bladder mass less than 50 mg. The percent muscle fraction was determined by histological analyses. The expression of C-terminal (SM1 and SM2) and N-terminal (SM-B and SM-A) isoforms of myosin heavy chain was analyzed by reverse transcriptase-polymerase chain reaction. RESULTS: Severely hypertrophied bladders had larger optimum volume (p >0.001) and generated less pressure in response to field stimulation (p >0.001) and KCl (p >0.01) with a slower rate of pressure generation than controls or sham operated mice. Increased SM1-to-SM2 and SM-A-to-SM-B ratios were noted in severely obstructed bladders relative to controls or sham operated mice (p <0.05). The muscle fraction decreased slightly in the severely hypertrophied group (p not significant). CONCLUSIONS: Our male mouse model of PBOO demonstrates an increase in bladder mass, larger capacity and significantly decreased pressure generation in the in vitro whole bladder model. Obstruction induced increases in the expression of C-terminal (SM1) and N-terminal (SM-A) myosin heavy chain isoforms.

Animals↗
PubMed2004

Giant bladder diverticula causing bladder outlet obstruction in children.

PURPOSE: Congenital giant diverticulum of the bladder is a consequence of deficiency in the detrusor musculature and has been reported in male infants as a rare cause of bladder outlet obstruction. MATERIALS AND METHODS: A 10-year retrospective review revealed 4 patients (3 boys and 1 girl) with bladder outlet obstruction due to a giant bladder diverticulum. Prenatal and postnatal clinical and imaging records were reviewed. RESULTS: Prenatal sonography was unremarkable in all patients. Three males (ages 4 months, 10 months and 3 years) had no medical history of voiding dysfunction, and 1 female (11 years) had the Ehlers-Danlos syndrome. While the girl presented with urinary tract infection, all patients presented with progressively decreasing urinary stream and urinary retention. Each patient underwent voiding cystourethrography (VCUG) and ultrasound. In each patient VCUG showed a giant (greater than 7 cm) bladder diverticulum that descended below the bladder neck and compressed the urethra during voiding. Vesicoureteral reflux was seen in 2 patients. Ultrasonography demonstrated moderate unilateral hydronephrosis in 2 patients. Bladder diverticulectomy was successfully performed in all patients, with ureteral reimplantation in 3. CONCLUSIONS: A giant congenital bladder diverticulum, when noted on VCUG to descend below the bladder neck, may lead to bladder outlet obstruction. To our knowledge we report the first case of a female presenting with bladder outlet obstruction due to a giant bladder diverticulum. Children with connective tissue disorders may be predisposed to this disorder, which must be excluded, regardless of gender, in all patients presenting with voiding abnormalities. Surgical diverticulectomy, often with ureteral reimplantation, is the preferred treatment, with excellent long-term results.

Child↗
PubMed2004

The physical characteristics of young males with varicocele.

OBJECTIVE: To determine if there is an association with habitus in young males with varicocele, as adolescent boys with varicoceles appear to be mostly taller and leaner than age-matched controls. PATIENTS AND METHODS: Retrospectively reviewing our records we obtained the height and weight of 43 consecutive males (mean age 14.3 years, range 11-19) under long-term follow-up for varicocele. The body mass index (BMI), heights and weights were compared with values from the respective growth charts for boys aged 2-20 years (Center for Disease Control and Prevention), and the statistical significance of differences determined using the chi-square test. RESULTS: The height and weight distributions of patients with varicocele indicated a significant deviation from normal in the 25-95th percentiles for stature and in the 25-75th for weight (P < 0.05). Deviations in BMI were insignificantly different from normal at each percentile. CONCLUSION: These results indicate that patients with varicocele are significantly taller and heavier than age-matched controls. Future studies to address the key areas identified in this study will help to further assess the distribution of the incidence of varicocele in closely defined subsets of adolescent growth and development, which may provide some insight into the cause of varicoceles.

Adolescent↗
PubMed2003

Obstruction-induced changes in urinary bladder smooth muscle contractility: a role for Rho kinase.

Detrusor smooth muscle (DSM) undergoes hypertrophy after partial bladder outlet obstruction (PBOO) in male rabbits, as it does in men with PBOO induced by benign prostatic hyperplasia. Despite detrusor hypertrophy, some bladders are severely dysfunctional (decompensated). In this study, the rabbit model for PBOO was used to determine the biochemical regulation of the contractile apparatus and force maintenance by the detrusor from decompensated bladders (DB). Bladders from sham-operated rabbits served as a control. On stimulation with 125 mM KCl, the DSM from sham-operated (SB) rabbits showed phasic contractions, whereas the detrusor from DB was tonic, exhibiting slow development of force, a longer duration of force maintenance, and slow relaxation. The Rho kinase (ROK) inhibitor Y-27632 enhanced the relaxation of precontracted DSM strips from DB. The enhancement of relaxation of the KCl-induced contraction of DB by Y-27632 was associated with dephosphorylation of myosin light chain (MLC20). The DSM extract from DB showed low phosphatase activity compared with that from SB. The DB also showed more Ca2+-independent MLC20 phosphorylation, which was partially inhibited by Y-27632. RT-PCR and Western blotting revealed similar expression levels of MLC kinase and ROK-alpha in SB and DB, but ROK-beta was overexpressed in DB. These results suggest that the ROK-mediated pathway is partly responsible for the high degree of force maintenance and slow relaxation in the detrusor from DB.

Amides↗
PubMed2003

Partial bladder outlet obstruction alters Ca2+ sensitivity of force, but not of MLC phosphorylation, in bladder smooth muscle.

Partial bladder outlet obstruction in the rabbit produces changes in bladder function similar to those seen clinically in patients with obstructive uropathies. Whole organ function is significantly altered, as are the smooth muscle cells inside the bladder wall. This study was designed to determine whether outlet obstruction alters smooth muscle function at the level of contractile filaments. Rabbit bladders were partially obstructed for 2 wk. Triton X-100 was used to provide a detergent-skinned bladder smooth muscle preparation that would allow control of the intracellular environment while the ability to shorten and develop force is maintained. Ca2+-force and Ca2+-myosin light chain (MLC) phosphorylation relations and maximal velocity of shortening were determined. The Ca2+ sensitivity of force was significantly lower in tissues from animals subjected to outlet obstruction compared with tissues from control animals. In contrast, no difference was noted in the Ca2+ sensitivity of MLC phosphorylation. Maximal levels of stress and MLC phosphorylation were similar in both animal groups. Maximal velocity of shortening was significantly slower in tissues from outlet-obstructed animals at all Ca2+ concentrations compared with tissues from control animals. Ultrastructurally, detergent skinning had little effect on structural integrity. Moreover, tissues from obstructed animals showed an increase in the number of sarcolemmal attachment plaque structures. We suggest that partial bladder outlet obstruction produces deleterious (e.g., decrease in Ca2+ sensitivity of force) and compensatory (e.g., increase in membrane attachment plaques) changes in bladder smooth muscle cells.

Animals↗
PubMed2003

Testis histopathology in boys with cryptorchidism correlates with future fertility potential.

PURPOSE: We studied the ability of testis biopsy to predict eventual fertility potential. MATERIALS AND METHODS: A total of 25 patients with unilateral undescended testis and 11 with bilateral undescended testes who previously underwent orchiopexy at a median age of 9 years were followed until after age 18 years. Semen analysis, testicular volume, follicle-stimulating hormone, luteinizing hormone, testosterone and inhibin B were compared to previously obtained biopsies of each testis. Biopsies were graded as mild, moderate or severe histology based on published data for normal and undescended testis histology. RESULTS: Patients with unilateral undescended testis and moderate histology were more likely to have a sperm density of greater than 20 million per cc than those with severe histology (p = 0.006), although no difference in hormonal parameters was noted. Patients with bilateral undescended testes and moderate histology were more likely to have normal follicle-stimulating hormone and inhibin B than those with severe histology (p = 0.05 and 0.002, respectively), although no difference in semen analysis was observed. Overall 7 of the 9 patients with bilateral undescended testes had less than 20 million sperm per cc. CONCLUSIONS: Testis biopsy provides useful prognostic information about semen analysis in patients with unilateral undescended testis. In the 9 patients with bilateral undescended testes testis biopsy divided them into normal and abnormal groups in terms of hormonal parameters. Testis biopsy was not able to provide additional prognostic information on semen analysis in patients with bilateral undescended testes since they were uniformly poor.

Adolescent↗
PubMed2002

The ascending testis and the testis undescended since birth share the same histopathology.

PURPOSE: The etiology of the ascending testis is controversial. We propose that ascending testis, defined as a testis previously thought to be descended and later noted to be out of the scrotum, is due to mild hypogonadotropic hypogonadism affecting both testes. The diagnosis of these low types of true undescended testes is difficult to make clinically in children since they are frequently confused with retractile testes. In this study we compared testicular biopsies in a group of boys with ascending testes with those in boys who had an undescended testis since birth (primary undescended testis). MATERIALS AND METHODS: Between 1985 and 1995, 91 patients with ascending testes underwent orchiopexy and bilateral testis biopsy. The total germ cell count, processus vaginalis status, age at surgery and whether followup was done by a pediatrician or pediatric urologist were compared in patients with ascending and unilateral primary undescended testes. RESULTS: The total germ cell count was similar in the undescended and the contralateral descended testis in patients with ascending and primary undescended testes. The processus vaginalis was more likely to be closed in ascending testes (57% versus 36%, p = 0.0001). Age at surgery and the total germ cell count were similar in patients followed by pediatricians and pediatric urologists. CONCLUSIONS: The ascending testis has the same germ cell count as the primary undescended testis. Yearly followup by the primary care physician is recommended for patients with retractile testes.

Biopsy↗
PubMed2002

Generation of a cell line with smooth muscle phenotype from hypertrophied urinary bladder.

We have established a cell line from hypertrophied rabbit urinary bladder smooth muscle (SM) that stably expresses SM myosin (SMM). These cells, termed BSM, are spindle shaped and form swirls, similar to the "hills and valleys" described for cultured aortic SM cells. Western blotting revealed that BSM expresses the amino-terminal SMM heavy chain isoform SM-B, the carboxy-terminal SM1 and SM2 isoforms, and SM alpha-actin. In addition, they express cGMP-dependent protein kinase G, made by contractile SM cells in vitro but not by noncontractile cells synthesizing extracellular matrix. Immunofluorescence studies indicate a homogeneous population of cells expressing alpha-actin and SMM, including the SM-B isoform, and karyotyping demonstrates a stable 4N chromosomal pattern. These cells also express calcium-dependent myosin light chain kinase and phosphatase activity and contract in response to the muscarinic agonist bethanechol. To our knowledge, BSM is the first visceral SM cell line that expresses the SM-B isoform and might serve as a useful model to study the transcriptional regulation of tissue-specific SMM isoforms in differentiation and pathological SM.

Actins↗
PubMed2002

Enhanced force generation by corpus cavernosum smooth muscle in rabbits with partial bladder outlet obstruction.

PURPOSE: Growing clinical evidence suggests that benign prostatic hyperplasia induced partial bladder outlet obstruction is associated with an increased incidence of erectile dysfunction. We determined whether corpus cavernosum smooth muscle from rabbits with partial bladder outlet obstruction show any molecular or functional differences versus controls. MATERIALS AND METHODS: Force generation and relaxation of corpus cavernosum smooth muscle 2 weeks after partial bladder outlet obstruction by 125 mM. KCl, phenylephrine and field stimulation were determined. Expression of total smooth muscle myosin and alternatively spliced smooth muscle myosin isoforms were determined by reverse transcriptase-polymerase chain reaction (RT-PCR), quantitative competitive RT-PCR, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis. Corpus cavernosum smooth muscle from sections of the penis were analyzed morphologically by immunofluorescence microscopy using antibodies to smooth muscle myosin and neurofilament protein. RESULTS: Corpus cavernosum smooth muscle from rabbits with partial bladder outlet obstruction generated 40% to 50% more force than that of sham operated rabbits in response to KCl or phenylephrine and was more difficult to relax. Although quantitative competitive RT-PCR and sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that corpus cavernosum smooth muscle from rabbits with partial bladder outlet obstruction expressed only slightly more total smooth muscle myosin at the messenger RNA and protein levels, expression of the high adenosine triphosphatase isoform SM-B increased 2-fold. Morphological examination of corpus cavernosum smooth muscle sections revealed decreased innervation and increased smooth muscle bundle size. CONCLUSIONS: We present the novel finding of molecular and functional changes in the corpus cavernosum smooth muscle associated with partial bladder outlet obstruction. Although the inclusion of sham operation ruled out direct injury during surgery, a change in corpus cavernosum smooth muscle innervation induced by nerve compression by the ligature is likely to induce trophic changes in the corpus cavernosum smooth muscle leading to over expression of the SM-B smooth muscle myosin isoform, increased contractility and impaired relaxation.

Animals↗