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Biomedical subjects

H Snyder

Publications and source records attributed to H Snyder.

At least 19 recordsLinked to original sources
PubMed1999

Primary follicular lymphoma of the testis in childhood.

BACKGROUND: Follicular lymphoma in childhood is rare. The authors present four unusual primary follicular lymphomas of the testis in children. METHODS: Tumor tissue was evaluated using light microscopy, immunohistochemistry, flow cytometry, and polymerase chain reaction (PCR) for immunoglobulin heavy chain (IgH) and bcl-2 gene rearrangements. Southern blot and immunohistochemical analyses were used to detect bcl-6 gene rearrangements and protein expression, respectively. RESULTS: Four young boys ranging in age from 3 to 10 years were diagnosed with Stage IE follicular large cell lymphoma (Grade 3). A B-cell phenotype was documented in all four cases; monoclonality was confirmed in three cases by demonstration of light chain restriction or clonal IgH gene rearrangement. None of the lymphomas expressed Bcl-2 or p53 protein, and bcl-2 gene rearrangements were not found in the three lymphomas studied. In contrast, Bcl-6 protein was expressed by all three lymphomas studied, and a bcl-6 gene rearrangement was detected in the one case analyzed by Southern blot. All four boys were treated by orchiectomy and combination chemotherapy and are alive with no evidence of disease 18-44 months following their initial diagnoses. CONCLUSIONS: Follicular lymphomas may rarely occur as primary testicular tumors in prepubertal boys and, when localized, appear to be associated with a favorable prognosis. In contrast to follicular lymphoma in adults, pediatric follicular lymphomas of the testis are usually of large cell type (Grade 3) and lack bcl-2 or p53 abnormalities. The identification, in one case, of a bcl-6 gene rearrangement suggests an alternate molecular pathogenesis for pediatric follicular lymphoma.

Child↗
PubMed1997

Mineralogical features associated with cytotoxic and proliferative effects of fibrous talc and asbestos on rodent tracheal epithelial and pleural mesothelial cells.

Inhalation of asbestos fibers causes cell damage and increases in cell proliferation in various cell types of the lung and pleura in vivo. By using a colony-forming efficiency (CFE) assay, the cytotoxicity and proliferative potential of three mineral samples containing various proportions of fibrous talc were compared to NIEHS samples of crocidolite and chrysotile asbestos in cell types giving rise to tracheobronchial carcinomas, i.e., hamster tracheal epithelial (HTE) cells, and mesotheliomas, i.e., rat pleural mesothelial (RPM) cells. Characterization of mineralogical composition, surface area, and size distributions as well as proportions of fibers in all mineral samples allowed examination of data by various dose parameters including equal weight concentrations, numbers of fibers >5 micron in length, and equivalent surface areas. Exposure to samples of asbestos caused increased numbers of colonies of HTE cells, an indication of proliferative potential, but fibrous talc did not. RPMs did not exhibit increased CFE in response to either asbestos or talc samples. Decreased numbers of colonies, an indication of cytotoxicity, were observed in both cell types and were more striking at lower weight concentrations of asbestos in comparison to talc samples. However, all samples of fibrous minerals produced comparable dose-response effects when dose was measured as numbers of fibers greater than 5 micron or surface area. The unique proliferative response of HTE cells to asbestos could not be explained by differences in fiber dimensions or surface areas, indicating an important role of mineralogical composition rather than size of fibers.

Animals↗
PubMed1994

Direct vesicoureteral scintigraphy: quantifying early outcome predictors in children with primary reflux.

UNLABELLED: This study quantifies some of the outcome predictors in a group of children with primary vesicoureteral reflux who were initially managed medically. METHODS: We studied 133 patients with primary reflux for 7.1 +/- 2.2 yr. Direct vesicoureteral scintigraphy (DVS) was used to prospectively measure the absolute bladder volume at which reflux began and the maximum volume of urine refluxed into the ureters during the filling and voiding phases of their first two DVS studies. Findings were related to outcome as defined by spontaneous resolution or the eventual need for reconstructive surgery. RESULTS: Medical management eventually failed in 35% of this sample. Patients who did not begin to reflux until their bladders had been filled to more than 60% total bladder capacity had a substantially smaller risk of surgery than those who began to reflux at smaller bladder volumes. Patients who refluxed a volume of urine back into their ureters that was less than about 2% of their total bladder capacity had a substantially smaller risk of surgery than those who refluxed more than 2%. The difference between groups was significant for both DVS variables (p < 0.001). CONCLUSION: Quantitative DVS contributes to the assessment of prognosis in children with vesicoureteral reflux who are managed medically.

Child↗
PubMed1993

Developmental aspects of bladder contractile function: evidence for an intracellular calcium pool.

Recent studies indicate that specific functional changes in smooth muscle accompany development and that these functional differences may relate to developmental alterations in intracellular calcium content. The possibility that neonatal bladder smooth muscle might be more permeable to calcium ions was tested using the radioligand H3 PN-200 and subsequent Scatchard analyses. No differences in either receptor density or the dissociation constants were noted in comparisons between neonatal and mature rabbit bladder smooth muscle. The sensitivity to calcium in isolated bladder smooth muscle strips exposed to high potassium was tested following calcium depletion. Calcium repletion was performed and dose response curves were generated, which showed that the neonatal strips had a significantly lower effective dose producing 50% of maximal response than their mature counterparts (1.5 versus 7.5 mM., p < 0.05). These findings are consistent with the hypothesis that intracellular binding and secondary calcium release are low in neonatal bladder smooth muscle, and that they increase with maturation. These studies are also consistent with the studies showing maturational increases in the intracellular binding and storage of calcium (sarcoplasmic reticulum), which have been reported in the developing rabbit and sheep myocardium.

Animals↗
PubMed1988

Gas chromatographic/mass spectrometric analysis of morphine and codeine in human urine of poppy seed eaters.

In this study, poppy seeds were examined for a natural constituent that might serve as a maker for the seeds' ingestion as opposed to opiate abuse. Thebaine was selected as possible marker, since it was found to be a component of all poppy seeds examined and was not a natural component of different heroin samples. During the course of this investigation, a new extraction and cleanup procedure was developed for the gas chromatographic/nitrogen phosphorus detection (GC/NPD) and gas chromatographic/mass spectrometric (GC/MS) analysis of morphine and codeine in urine. A linear response, over a concentration range of 25 to 600 ng/mL, was obtained for codeine and morphine (r = 0.9982 and 0.9947, respectively). The minimum detectable level (LOD) and limit of quantitation (LOQ) for morphine were 10 and 30 ng/mL, respectively; whereas LOD and LOQ for codeine were 2 and 8 ng/mL, respectively. The coefficients of variance (CV, n = 6) for morphine and codeine analyses at the 100-ng/mL level were 13.3 and 4.6%, respectively. This procedure was used for the analysis of urine samples from five poppy seed eaters who each ingested 200 g of poppy seed cake. Results indicated that significant amounts of morphine and codeine are excreted in urine and that in all subjects, at least at one point in time, the apparent morphine concentration as determined by radioimmunoassay (RIA) analysis exceeded the cutoff value (300 ng/mL) established for screening. Thebaine was not detected in urine specimens collected following poppy seeds ingestion and thus could not be used as a marker.

Chromatography, Gas↗
PubMed1987

Selecting initial therapy for pediatric genitourinary cancers.

A few decades ago, there were few choices in the initial management of children with genitourinary tumors. Radical surgical removal was the only line of attack that promised any chance of survival. Improvement in the results of multimodal therapy in the last 15 years have radically altered the outlook for these children, hence the choice of therapy. As with other childhood cancers, the choice of therapy is based on risk-benefit evaluations of the roles of surgery, irradiation, and chemotherapy, since all three modalities have their associated morbidities. Current emphases are on preservation of function without compromising cure. The large cooperative clinical trials have emphasized this aspect of pediatric oncology. They have demonstrated, for example, that radiation therapy can be omitted from primary management of early stage Wilms' tumor patients who are given adequate adjuvant chemotherapy as can both radiation therapy and ablative surgery in certain cases of early stage rhabdomyosarcoma. Routine retroperitoneal node dissections have been shown to be of dubious diagnostic or therapeutic value in boys with testicular cancers. The need for bilateral oophorectomy in girls with dysgerminoma can similarly be questioned. Choices of initial therapy, therefore, are not static. They are becoming wider with each advance in multimodal therapy. Clinicians must keep abreast of the results of clinical trials so they can offer their patients the combination of treatments that will preserve function, and produce the smallest number of late complications without jeopardizing survival chances.

Adolescent↗
PubMed1987

Treatment of cryptorchidism with low doses of buserelin over a 6-months period.

In a collaborative study, 48 prepubertal boys with undescended testes ranging in age from 15 months to 11 years were treated with low-dose intranasal buserelin following an every-other-day programme for a period of 6 months. Urinary LH, FSH, and testosterone were not altered during the treatment period. Boys over 7 years of age experienced a slight but significant rise in testosterone at the end of treatment. Testicular descent was achieved in only 17% of boys. In the remainder, bilateral testicular biopsies were obtained during orchiopexy. Grouped analysis showed a significant increase in the number of germ cells per tubule in both unilateral and bilateral cryptorchid boys, suggesting that buserelin treatment of the testis in a cryptorchid position is capable of improving fertility potential. If time-matched controls are compared to treated boys of the same age, again a significant difference is observed indicating that buserelin treatment does increase the germ cell count.

Administration, Intranasal↗
PubMed1987

Long-term effect of luteinizing hormone-releasing hormone analogue (buserelin) on cryptorchid testes.

We studied 48 prepubertal boys with cryptorchidism between 1 year 3 months and 11 years old who were treated with buserelin every other day for 6 months. Urinary luteinizing and follicle-stimulating hormones, and testosterone remained unchanged during the entire treatment period. In boys older than 7 years a slight but significant increase in testosterone was noted in the first morning voided urine at the end of treatment. Testicular biopsies were obtained at orchiopexy in all patients in whom testicular descent was not complete (83 per cent). A significant increase in the number of germ cells was observed in patients with unilateral and those with bilateral cryptorchidism, indicating that 6 months of buserelin therapy improved the fertility status even when testes were in an undescended position during treatment.

Administration, Intranasal↗
PubMed1987

Epididymitis in infants and boys: underlying urogenital anomalies and efficacy of imaging modalities.

Of 47 children diagnosed as having epididymitis between 1975 and 1985, 8 of 17 prepubertal patients (47 per cent, or 17 per cent of the total group), including 3 of 4 infants (75 per cent), had an underlying urogenital anomaly. Thus, patients with epididymitis secondary to an underlying anomaly present at an earlier age. The common finding in patients with underlying anomalies was a pathological connection between the urinary tract and the genital duct system or bowel. Coliform urinary infections predominated in patients with underlying anomalies (4 of 6). Although a positive urine culture suggested an underlying anomaly (positive predictive value 0.60), a negative culture virtually ruled out an anomaly (negative predictive value 1.00). Of the 8 patients with underlying anomalies 6 underwent voiding cystourethrography and 6 underwent excretory urography, and the diagnosis was established in 6 (100 per cent) and 4 (67 per cent), respectively. Thus, voiding cystourethrography has the greatest diagnostic yield. Any prepubertal patient with epididymitis merits a complete urological evaluation, including a urine culture, voiding cystourethrography and excretory urography to rule out an underlying urogenital anomaly, which often is amenable to an operation. Surgery often involves severance of the pathological urogenital or urinary-fecal connection and it was successful in 7 of our 8 patients.

Adolescent↗
PubMed1986

Testicular histology in children with unilateral testicular torsion.

Testicular biopsies from 38 boys at the time of unilateral testicular torsion were studied retrospectively. Of the patients 30 were adolescent and 8 were prepubertal. In 18 boys biopsy of the torsed testis only was performed, while in another 18 bilateral testis biopsy was obtained. The remaining 2 patients had biopsy of the contralateral testis only because the torsed testis was infarcted completely. After allowances were made for the acute testicular changes associated with the torsion itself, significant pre-existing testicular abnormalities could be identified in 20 of the 38 patients (53 per cent), including the Sertoli-cell-only syndrome (7), partial Sertoli-cell-only syndrome (4), defective spermatogenesis (8) and mucous plugs caused by cystic fibrosis inducing tubular changes (1). In 70 per cent of the biopsies from prepubertal boys the number of spermatogonia per tubule was diminished. In adolescent boys the mean number of late spermatids also was diminished severely in the contralateral and torsed testes. Pronounced atrophy of Leydig cells was found in all but 1 testis examined. The presence or absence of a morphological blood-testis barrier did not appear to be related to pathological changes in the contralateral testis. These observations suggest that infertility in patients with unilateral testicular torsion may be a consequence of a pre-existing testicular pathological condition.

Adolescent↗
PubMed1981

Isolated bladder neck obstruction of undetermined etiology (primary) in adult male: recognition and management.

Varying degrees of isolated bladder neck obstruction of undetermined etiology were identified with micturitional vesicourethral static pressure profiles. Our experience with the urodynamic studies in 15 patients suggests that isolated bladder neck obstruction is a real entity in young adult males. Our experience also suggests that pharmacologic success with alpha-adrenergic blockade of the dosage tolerated by the patients is inconsistent. Successful clinical results achieved with appropriate bladder neck surgery could be confirmed with uroflowmetry and detailed urodynamic studies during postoperative period.

Adult↗
PubMed1981

Urodynamic localization of isolated bladder neck obstruction in men: studies with micturitional vesicourethral static pressure profile.

Micturitional vesicourethral static pressure profile, a method of recording the static (lateral) component of voiding pressure in the successive urethral segments contiguous with the bladder, has allowed us to establish directly the site and degree of bladder outlet obstruction in 16 men. The diagnosis of isolated bladder neck obstruction was confirmed with greater confidence by using this technique with a 10F trilumen catheter in conjunction with uroflowmetry and radiologic studies. Repeat studies with a 5F single lumen catheter have suggested that the obstructions recognized with the 10F catheter ware not entirely artifactual. Our experience with this technique in several men with non-neurogenic bladder neck obstruction indicates the importance of including this study in the urodynamic armamentarium.

Adult↗
PubMed1981

Urodynamic evaluation of prostatic enlargements with micturitional vesicourethral static pressure profiles.

We studied 58 men with prostatism, who were between 58 and 75 years old, with micturitional vesicourethral static pressure profiles. The study consisted of recording static (lateral) pressures of successive segments of the posterior urethra during voiding, with synchronous monitoring of the vesical pressure activity. An abnormal pressure decrease across the supramontane urethra was considered to be a functional compromise to the prostatic urethra. The studies indicated that the degree of prostatic urethral obstruction was not related to the clinical and endoscopic assessment of prostatic enlargement. Three major patterns emerged from our studies: 1) moderate to severe prostatic enlargement with severe obstruction, 2) moderate to severe prostatic enlargement with minimal or no obstruction and 3) minimal prostatic enlargement with severe obstruction. Also, a good correlation became apparent between micturitional vesicourethral static pressure profilometry and uroflowmetry.

Aged↗
PubMed1976

Anterior detrusor tube repair for urinary incontinence in children.

The technique, complications and results of an anterior detrusor tube repair for urinary incontinence in children is described. It appears that this procedure is appropriate only for selected cases of urinary incontinence but that it is an operation which should be within the paediatric urologist's repertoire. It is simple to perform, but care should be taken, by omental packing, to prevent a sharp posterior lip to the newly formed bladder neck.

Child↗