Transit peptides play a major role in the preferential import of proteins into leucoplasts and chloroplasts

The in vitro import characteristics of six different precursors of plastid proteins were assessed to determine differences in the protein import pathways of leucoplasts and chloroplasts. Five of these precursor proteins are destined to different subchloroplast sites, and one is a leucoplast stromal precursor protein. The results indicate that some of these precursors can be imported equally into both plastid types and others preferentially into one type of plastid versus the other. The ability of plastids to import different proteins correlates with the in vivo steady state levels of these proteins. Additional differences were also observed in the intraorganellar portion of the translocation pathway for two thylakoidal proteins. The differences in import characteristics were found to be predominantly governed by information in the transit peptides, since attachment of the various transit peptides to different plastid and foreign proteins demonstrated that the import behavior of the proteins is transferable with the transit sequence. These results indicate that the import mechanisms of leucoplasts and chloroplasts are sufficiently different such that the plastids respond differently to the information present in the transit peptides.

Vesicoureteral reflux: practical aspects of evaluation and management

The efficacy of both medical and surgical therapy for vesicoureteral reflux (VUR) has been well established. Controversy remains, however, regarding who should be evaluated for the presence of VUR, who should undergo corrective surgery, who should be treated medically and for how long. Medical treatment requires many years of continuous antibiotic prophylaxis, so compliance with therapy is essential. Many children are lost to followup, however, and remain untreated after a medical regimen is started. This large number of untreated children raises issues of the appropriateness of blanket therapeutic recommendations for all children with VUR and challenges the clinician to devise more effective treatment strategies.

[A clinical study of polytetrafluoroethylene (polytef) as a substitute for conjunctiva]

Burn, tumor or congenital reasons may cause coloboma of conjunctiva. We were seeking for a thin membrane to cover the coloboma that would make the survival peripheral conjunctiva to grow and self-repair so that mucosa transplantation could be avoided. A polytetrafluoroethylene membrane of 0.1 mm thickness, 2-3 mm larger in diameter than the coloboma was sutured in place. After 2-3 weeks the membrane was removed. A total of 16 patients underwent the operation. Of them there were 2 of plasmacytoma, 5 of symblepharon, 6 of contracture of socket of eyeball and 3 of complex pterygium. In two to three weeks, the region of coloboma of conjunctiva was found being repaired. On an average 12 months' follow-up study, the eyeball movements in all cases were normal and the eyes looked symmetric. No symblepharon was found. We conclude that the polytetrafluoroethylene is a non-toxic, smooth, non-adhesive and non-distort substance resistant to high and low temperatures. When used as a substitute for conjunctiva at the region of coloboma of conjunctiva, it makes the peripheral normal conjunctiva tissues to grow and repair the coloboma.

The elimination of diazepam in Chinese subjects is dependent on the mephenytoin oxidation phenotype

1. The disposition of diazepam and desmethyldiazepam was studied in 21 healthy male Chinese subjects who were phenotyped with mephenytoin. Four poor metabolizers (PM) were identified by phenotyping with mephenytoin and by genotyping for CYP2C19. 2. Serum diazepam and desmethyldiazepam concentrations were measured by high performance liquid chromatography in samples drawn up to 24 days after administration. 3. The plasma elimination half-lives of diazepam (100.8 +/- 32.3 h) and desmethyldiazepam (219.9 +/- 62.7 h) in PMs were significantly longer than those (34.7 +/- 23.0 h for diazepam, 103.1 +/- 25.9 h for desmethyldiazepam) of the 17 phenotyped extensive metabolizers (EM), and those (30.8 +/- 24.9 h for diazepam, 103.1 +/- 27.5 h for desmethyldiazepam) of the five genotyped EMs. 4. The mephenytoin S/R ratios were significantly correlated with the plasma half-lives of diazepam (r = 0.543, P < 0.05) and desmethyldiazepam (r = 0.522, P < 0.05), and with the clearance (r = -0.524, P < 0.05) of diazepam in 21 subjects. 5. These results are compatible with the conclusion that both diazepam and desmethyldiazepam are metabolized by cytochrome P450 CYP2C19 in the Chinese population. 6. The mephenytoin S/R ratios in nine EMs who drank alcohol frequently were significantly higher than those of seven EMs who were non-drinkers, but the plasma kinetics of diazepam and desmethyldiazepam were not significantly different between the two groups. The explanation for these finding is not clear.

Expanded followup of intravesical oxybutynin chloride use in children with neurogenic bladder

PURPOSE

We evaluated the long-term results of intravesical oxybutynin chloride use in children with neurogenic bladders who could not tolerate or whose conditions were refractory to oral therapy.

MATERIALS AND METHODS

We reviewed our experience with 28 children (myelomeningocele in 27 and imperforate anus in 1) who presented with urinary incontinence and/or elevated bladder pressures refractory to intermittent catheterization and oral anticholinergic medication. Intravesical oxybutynin was administered to each child by instillation of 5 mg. crushed oxybutynin chloride in 10 cc sterile saline 2 times daily during catheterization.

RESULTS

Seven patients (25%) could not tolerate intravesical oxybutynin secondary to anticholinergic side effects. The remaining 21 children have been followed on intravesical oxybutynin for a mean of 35 months (range 3 to 67). Of these 21 children 12 (57%) became completely dry day and night, 5 (24%) achieved daytime continence between catheterizations and 4 (19%) remained clinically unchanged with 2 in diapers. On urodynamics these 21 patients had increased bladder capacity of up to 1,150% (mean 237%, p < 0.0001) and decreased mean maximum filling pressures of -31% (p = 0.002).

CONCLUSIONS

Although a number of patients continued to have anticholinergic side effects, a majority had significant improvement in urodynamic parameters and continence. The response appears to be durable, and it spares many of these children from undergoing bladder augmentation.

Sibling reflux: a dual center retrospective study

PURPOSE

Siblings of index patients with vesicoureteral reflux are known to have an increased incidence of reflux. Previous reports may be biased due to significantly more female siblings undergoing screening. In addition, it has been suggested that screening is unnecessary in older children.

MATERIALS AND METHODS

We retrospectively reviewed the records of probands with vesicoureteral reflux. A total of 422 families comprising 622 siblings was identified at our centers from 1985 to 1994. Of the 255 boys and 277 girls newborn to 16 years old (mean age 6.2 years) 85% were evaluated. Almost 43% of the probands (225) were older than 7 years.

RESULTS

Vesicoureteral reflux was noted in 144 siblings (52 boys and 92 girls, 27%). The majority had low grade reflux but in 111 (77%) maximum reflux grade was II or III. Reflux nephropathy was demonstrated on a nuclear renal scan in 18 of the 132 tested siblings (13.6%). In all of these children reflux was grades II to IV and 27% were older than 10 years.

CONCLUSIONS

When vesicoureteral reflux is discovered, all siblings should be considered for screening. The evaluation of older siblings remains controversial, since they comprise only a small fraction of all siblings with reflux but may have a significant portion of reflux nephropathy. There was a 27% overall incidence with a 33% rate in girls. The incidence of reflux in siblings decreased after age 7 years but reflux nephropathy was identified even in the older children.

Adsorption of bacteriocins by ingestible silica compounds

Bacteriocins including nisin, pediocin PO2, brevicin 286 and piscicolin 126 were adsorbed from culture supernates by various food-grade porous silica anti-caking agents and the food colourant, titanium dioxide. All the porous silica (calcium silicate or silicon dioxide) materials showed substantial capacity in adsorbing bacteriocin activities from the culture supernate and biological activity was recovered in the adsorbents. In contrast, the food colourant titanium dioxide adsorbed most of the bacteriocin activity from the supernate, with minimal biological activity retained in the adsorbent. Experiments with piscicolin 126 showed that optimum adsorption could be achieved with Micro-Cel E within 30 min, independent of the supernate pH (2.0-10.0). Piscicolin activity of up to 5 x 10(7) AU g(-1) of Micro-Cel E was obtained after adsorption from culture supernates and the adsorbed piscicolin demonstrated substantial biological activity against Listeria monocytogenes in both broth and a milk growth medium.

An analysis of social and economic factors associated with followup of patients with vesicoureteral reflux

PURPOSE

Nonsurgical treatment of vesicoureteral reflux requires antibiotic prophylaxis and long-term surveillance. We examined factors that affect followup compliance and influence quality of care in these children.

MATERIALS AND METHODS

We retrospectively reviewed the records of 288 boys and 742 girls with vesicoureteral reflux.

RESULTS

Of the children treated nonsurgically for vesicoureteral reflux 34% were lost to followup and the majority (80%) were not monitored beyond the 1-year followup appointment. Older maternal age (36 years or older) was significantly associated with improved followup compliance. Paternal age, primary physician type, medical insurance type, income, education level and environment (urban, suburban or rural) were not significant.

CONCLUSIONS

Approximately a third of children treated nonsurgically for vesicoureteral reflux will be lost to followup. Only older maternal age predicts for good compliance. Preconceptions about compliance on the basis of other factors, such as socioeconomic status and primary physician type, may be incorrect. Furthermore, the notion that certain forms of medical insurance plans may help to promote followup may also be unsupported. These children would benefit from efforts to improve compliance with a medical regimen or early correction of reflux.

Characterization of the chemical and antimicrobial properties of piscicolin 126, a bacteriocin produced by Carnobacterium piscicola JG126

A novel peptide bacteriocin produced by the lactic acid bacterium Carnobacterium piscicola JG126 isolated from spoiled ham was purified and characterized. This bacteriocin, designated piscicolin 126, inhibited the growth of several gram-positive bacteria, especially the food-borne pathogen Listeria monocytogenes, but had no effect on the growth of a number of yeasts and gram-negative bacteria. Bactericidal activity was not destroyed by exposure to elevated temperatures at low pH values; however, bactericidal activity was lost at high pH values, especially when high pH values were combined with an elevated temperature. Piscicolin 126 activity was not affected by catalase, lipase, or lysozyme but was destroyed by exposure to a range of proteolytic enzymes. Piscicolin 126 was purified to homogeneity and was found to be a peptide having a molecular weight of 4,416.6 +/- 1.9. A sequence analysis revealed that this compound is a cystibiotic (class IIa) bacteriocin containing 44 amino acid residues and one intrapeptide disulfide ring. Piscicolin 126 has regions of homology with some other bacteriocins obtained from lactic acid bacteria and is most closely related to sakacin P and pediocin PA-1 (levels of identity, 75 and 55%, respectively). Addition of piscicolin 126 to a devilled ham paste test food system inhibited the growth of L. monocytogenes for at least 14 days. Piscicolin 126 was more effective than two commercially available bacteriocin preparations tested in the same system.

A food-grade process for isolation and partial purification of bacteriocins of lactic acid bacteria that uses diatomite calcium silicate

Bacteriocins, including nisin, pediocin PO2, brevicin 286, and piscicolin 126, were extracted from fermentation media by adsorption onto Micro-Cel (a food-grade diatomite calcium silicate anticaking agent) and subsequent desorption. The optimal conditions for desorption of piscicolin 126 were determined and applied to other bacteriocins, and the relative purities of the desorbed preparations were compared. Piscicolin was not successfully desorbed from Micro-Cel at pH 1.0 to 12.0, with organic solvents, or by increase of ionic strength up to 1 M NaCl. However, 25 and 75% of the bacteriocin activity was desorbed by using 1% sodium deoxycholate and 1% sodium dodecyl sulfate (SDS), respectively. Higher levels (up to 100%) of desorption were achieved by repeated elution or by an increase in surfactant concentration. Desorption of piscicolin with 1/10 volume of SDS solution resulted in a preparation with 10 times concentration in activity, equivalent to that of ammonium sulfate preparations (409,600 to 819,200 activity units/ml). Determination of organic nitrogen (N) content revealed that the desorbed piscicolin preparations were substantially free of proteinaceous substances (approximately 92 to 99%) compared with original culture supernatants and ammonium sulfate preparations. Nisin, pediocin, and brevicin were also desorbed with 1% SDS with a similar level of purification.

Reduced tumorigenicity of metastatic human lung cancer cell subline (PGCL3) transfected with hRAR beta gene

The recombinant PSG5-RAR beta plasmid and the G418-resistant PSV2 neo plasmid (10.1) were cotransfected into PGCL3 cells by coprecipitation with calcium phosphate. The transfectants CR3 and CR4, which expressed the RAR beta gene, were identified by Northern blot hybridization. The results showed that the in vitro growth and invasion of CR3 and CR4 were dramatically reduced compared to the control-transfected cell (CSV1). Furthermore, the colony-forming abilities in soft agar and the tumorigenicity in nude mice of CR3 and CR4 were abrogated. Our results suggests that RAR beta functions not only as a receptor mediating the RA action, but also as a suppressor in lung tumorigenesis.

Two new loci for hybrid sterility in cultivated rice (Oryza sativa L.)

Female gamete abortion in Indica-Japonica crosses of rice was earlier identified to be due to an allelic interaction at the S-5 locus on chromosome 6. Recently, in other crosses of rice, similar allelic interactions were found at loci designated as S-7 and S-8, located on chromosomes 7 and 6 respectively. All of them are independent of each other. At the S-5 locus, Indica and Japonica rice have S-5 (i) and S-5 (j) alleles respectively and Javanicas, such as Ketan Nangka, have a neutral allele S-5 (n) .The S-5 (i) /S-5 (j) genotype is semi-sterile due to partial abortion of female gametes carrying S-5 (j) , but both the S-5 (n) /S-5 (i) and S-5 (n) /S-5 (j) genotypes are fertile. The S-5 (n) allele is thus a "wide-compatibility gene" (WCG), and parents homozygous for this allele are called wide-compatible varieties (WCV). Such parents when crossed with Indica or Japonica varieties do not show F1 hybrid sterility. Wide-compatible parents have been used to overcome sterility barriers in crosses between Indica and Japonica rice. However, a Javanica variety, Ketan Nangka (WCV), showed typical hybrid sterility when crossed to the Indian varieties N22 and Jaya. Further, Dular, another WCV from India, showed typical hybrid sterility when crossed to an IRRI line, IR2061-628-1-6-4-3(IR2061-628). By genetic analyses using isozyme markers, a new locus causing hybrid sterility in crosses between Ketan Nangka and the Indicas was located near isozyme loci Est-1 and Mal-1 on chromosome 4, and was designated as S-9. Another new locus for hybrid sterility in the crosses between Dular and the IR2061-628 was identified and was found linked to four isozyme loci, Sdh-1, Pox-2, Acp-1 and Acp-2, on chromosome 12. It was designated as S-15. On the basis of allelic interactions causing female-gamete abortion, two alleles were found at S-9, S-9 (kn) in Ketan Nangka and S-9 (i) in N22 and Jaya. In the heterozygote, S-9 (kn) /S-9 (i) , which was semisterile, female gametes carrying S-9 (kn) were aborted. The hybrid of Dular and IR2061-628, with a genetic constitution of S-15 (Du) /S-15 (i) , was semi-sterile and the female gametes carrying S-15 (Du) were aborted. A Japonica tester variety, Akihikari, and an Indica variety, IR36, were found to have neutral alleles, S-9 nand S-15 n, at these loci, in addition to S-7 nand at S-7. The accumulation of three neutral alleles into a breeding line should help solve the hybrid sterility problem in wide crosses of rice.

Production of brevicin 286 by Lactobacillus brevis VB286 and partial characterization

Brevicin 286 was produced by Lactobacillus brevis VB286 isolated from vacuum-packaged meat and was partially purified by ammonium sulphate precipitation, gel filtration and dialysis. The bacteriocin was susceptible to proteolytic enzymes, stable to heating at 100 degrees C particularly under acidic against Listeria sp. Production of brevicin 286 was optimal during exponential growth at 20 degrees C. Higher rates of cell growth occurred between 30 and 37 degrees C but with little or no expression of brevicin 286. A food-grade formulation consisting of 4% yeast extract and 1% glucose was found to be adequate for optimal brevicin 286 production and the bacteriocin-containing culture supernate was successfully spray dried with full recovery of antibacterial activity in the resultant powder.

Toilet habits of children evaluated for urinary tract infection

The toilet habits of 77 girls and 24 boys who were evaluated after having a urinary tract infection were examined prospectively. Children with known urological conditions that can predispose to urinary tract infections were excluded. A voiding cystourethrogram and renal ultrasound were performed, and a diary of toilet habits was obtained for all patients. Six children were lost to followup. Of the remaining 95 children imaging studies were negative in 60 (negative imaging group) and positive in 35 (positive imaging group). Only 10% of the negative imaging group were without constipation or abnormal voiding compared to 60% of the positive imaging group (p = 0.0001). Toilet habits can affect the development of urinary tract infections. Our data suggest that the evaluation of urinary tract infection should include an inquiry into these habits. Among children with negative imaging studies there may be functional problems that promote the development of urinary tract infections.

Regional renal blood flow measurements using radioactive microspheres in a chronic porcine model with unilateral vesicoureteral reflux

95Niobium labeled radioactive microspheres were used to determine regional renal blood flows in a porcine model of chronic sterile vesicoureteral reflux. Unilateral vesicoureteral reflux was surgically created in 5 mini-pigs and regional renal blood flows were determined by microsphere injection 6 months later. The contralateral nonrefluxing kidney acted as a control. There was a significant reduction of flow in the inner cortical regions of the middle (78% of control, p < or = 0.0437) and lower poles (69% of control, p < or = 0.0274), and the juxta-medullary cortical region of the lower pole (67% of control, p < or = 0.0124). There was no difference in flow in the other regions or when comparing whole kidneys. There were no differences between refluxing and nonrefluxing kidneys when comparing ratios of inner to outer cortical flow level by level. These observations are in contrast to those in acutely created vesicoureteral reflux in a porcine model, which had no significant differences in flow in any region using the microsphere technique. Decreases of blood flow in certain cortical regions may help explain some of the physiological changes in vesicoureteral reflux in children and experimental models of reflux.

Import characteristics of a leucoplast pyruvate kinase are influenced by a 19-amino-acid domain within the protein

Two cDNA clones encoding distinct forms of plastid pyruvate kinase (designated Pka and Pkg) have recently been characterized. Pkg is found in both leucoplasts and chloroplasts, whereas Pka is present only in leucoplasts. The precursors of these proteins have different in vitro import characteristics. The Pkg precursor behaves like a typical stromal protein precusor with both types of plastid. In contrast, Pka precursors accumulate on the outer envelope membrane of leucoplasts under the same assay conditions and require a higher level of ATP for import into the organelle. Interestingly, the binding of Pka precursors to chloroplasts cannot be detected at any tested level of ATP even though the precursors are imported into the organelle at higher concentrations of ATP. Various N-terminal deletions and chimeric fusions were used to examine the translocation signaling mechanism of the Pka precursor. The N-terminal 83-amino-acid segment of Pka contains a transit peptide that is capable of directing dihydrofolate reductase and the mature body of Pkg into both types of plastid. Unlike the complete Pka precursor, these fusion proteins behave like typical stromal protein precursors. The behavior of the Pka transit peptide is influenced by a 19-amino-acid domain (-P-S-S-I-E-V-D-A-V-T-E-T-E-L-K-E-N-G-F-) located immediately downstream of the N-terminal 83-residue segment. Deletion of this domain from Pka alters its import properties such that it resembles a typical stromal protein precursor. Re-introduction of the 19-residue domain into the Dhfr fusion protein alters its import characteristics to resemble that of the complete Pka precursor. This 19-amino-acid domain can also influence the function of transit sequences from other precursors when it is placed immediately behind the transit peptide. These results suggest that this 19-amino-acid domain plays an important role in governing the import characteristics of the Pka precursor. We have named this 19-residue segment the "import modifying domain."

Intrascrotal epidermoid cyst with extension into the pelvis

An 8-year-old boy presented with an asymptomatic extratesticular, scrotal epidermoid cyst with extension across the urogenital diaphragm into the pelvis. While routine contrast studies and ultrasound were performed, magnetic resonance imaging was most useful in depicting the anatomical boundaries of the lesion, including the intrapelvic extension. Complete excision was performed transcrotally. The lesion is histologically indistinguishable from epidermoid cysts found elsewhere in the external genitalia, that is the penis, scrotum or testis. The etiology is unknown but it may represent a monolayer teratoma of germ cell origin or abnormal embryological closure of the median raphe.

The regulation of euchromatin and heterochromatin by histones in yeast

Yeast chromosomes may lack the linker histone H1 (normally required to compact 10 nm beads-on-a-string fiber into the 30 nm fiber) and there is no cytological evidence for higher order fiber structure but they do contain regions which correspond to euchromatin and heterochromatin of higher eukaryotes. Both euchromatin and heterochromatin contain nucleosomal particles (composed of two molecules each of H2A, H2B, H3 and H4), however histones have been shown to regulate genes in these regions in quite different ways. The mechanisms by which such regulation occurs are the topic of this paper.

Fish oil and cell proliferation kinetics in a mammary carcinoma tumor model

In vivo bromodeoxyuridine (BrdUrd) labelling and bivariate BrdUrd/DNA analysis was used to evaluate cell cycle kinetics in a rat tumor model known to be sensitive to dietary fatty acid manipulation. Fish oil supplementation significantly reduced the rate of BrdUrd movement relative to DNA content, indicating prolongation of the DNA replication time. This finding, which accounted for most of the decrease in tumor growth rate in the fish oil-fed group, represents the first description of an alteration in S phase duration by an extrinsic factor. The significance of this finding is discussed in relation to current understanding of cell cycle regulation. Fish oil feeding is associated with slower growth rate in certain tumors (1,2). According to current concepts of cellular proliferation (3), regulation of growth by extrinsic factors is thought to precede the S phase. This statement is based on the notion that, within a given cell type, DNA replication time (S phase duration) is constant (4-6). Extensive evidence also supports an on/off mechanism of cell cycle regulation at the level of entry into the S phase (3). In this report, we present evidence showing, for the first time, that the S phase duration of fat-responsive tumor cells can be altered by dietary manipulation of fatty acids. Furthermore, these differences in S phase duration appear to account for all the in vivo variation in tumor growth resulting from fish oil feeding. Although the mechanism of this phenomenon remains unclear, our observations support increasing evidence for a regulatory step at the level of the nucleus. They are also important for understanding the relationship between dietary fat and tumor growth.

Molecular characterization of plastid pyruvate kinase from castor and tobacco

Clones encoding two different forms of plastid pyruvate kinase (PKp; EC 2.7.1.40) have been isolated from both castor and tobacco seed cDNA libraries. One form, designated PKpA, from castor was described in a previous report, and the tobacco homologue of PKpA has now been isolated. In addition, a second cDNA, designated PKpG, has been identified and sequenced in both species. Western blot analysis, using antibodies raised against protein overexpressed from these clones, indicates that they encode the two predominant polypeptides of plastid pyruvate kinase from developing castor endosperm. In castor, both PKpA and PKpG are encoded by single genes. In the allotetraploid Nicotiana tabacum, there are two copies of each, one derived from each of the progenitors of this species. The expression of the genes for PKpA and PKpG was examined in various tissues from both castor and tobacco. In castor, both forms are expressed in developing and germinating endosperm and in the root but neither is expressed in the leaf. In tobacco, both forms are expressed in developing seeds but in mature tissues, PKpA is most abundant in roots and PKpG in leaves.

Transepithelial transport of tyramine across filter-grown MDCK cells via a poly(D-lysine) carrier

In order to investigate the advantage of using membrane-adsorptive carriers to mediate drug transport across epithelial tissue, we have prepared disulfide- and thioether-linked conjugates of tyramine (tyn) as a model drug to a cationic, nondegradable carrier, poly(D-lysine) (PDL). The transport properties were evaluated using microporous filter-grown Madin-Darby canine kidney (MDCK, strain I) epithelial cells, and we have determined that: (a) the [125I]tyn-SS-PDL conjugate predominantly transported [125I]tyn in the apical-to-basal direction (20-fold greater transport vs. basal-to-apical); (b) [125I]tyn-SS-PDL elicits a 10-fold greater degree of [125I]tyn transport than [125I]tyn-S-PDL, thus demonstrating the importance of the reducible disulfide linkage for [125I]tyn transport to occur; (c) 125I-radioactivity recovered in the basal media was determined to be 95% [125I]tyn-containing small molecules, thus demonstrating the release of [125I]tyn from its PDL carrier; (d) the apical addition of an anionic species, heparin, completely blocks apical-to-basal transport of [125I]tyn, indicating the importance of PDL-mediated binding to the apical membrane for transport to occur; (e) apical-to-basal transport proceeds via non-lysosomal pathways, as lysosomal inactivation by NH4Cl exposure does not inhibit transport, and (f) the addition of a membrane-impermeable inhibitor of disulfide reduction, bisdithionitrobenzoic acid (DTNB), to the apical media inhibits transport by approximately 70%, indicating the importance of apically-localized disulfide reducing reactions for transport of [125I]tyn. Pulse-chase studies indicate that there is no paracellular leakage of conjugate, and the ratio of recycled:membrane-associated:transported [125I]tyn fragment following chase is 4:2:1.

Two-stage repair for severe hypospadias

In 39 patients a 2-stage modified Belt-Fuqua repair was performed for severe hypospadias and chordee. Patient age at initial surgery averaged 2 years and stage 2 was done 7 months later. Testosterone was given before stage 1 to 22 patients (56%) and before both stages to 13 (33%). Of 5 patients with intersex 2 had mixed gonadal dysgenesis, 1 was a true hermaphrodite and 2 were 46 XX male subjects. The preoperative meatal location was subglanular in 9 cases, mid shaft in 8, proximal shaft in 2, penoscrotal in 15 and perineal in 5. Those with subglanular meatus had hypoplastic distal urethras and severe chordee. A dorsal Nesbit procedure for chordee correction was done in 24 cases (62%). Neourethral length ranged from 3 to 7 cm. (average 4 cm.) and average followup was 16 months. Neourethral diverticula developed in 8 cases (21%) and they were repaired uneventfully an average of 7 months (range 2 to 24) after stage 2. Minor urethral strictures (3 distal and 4 proximal) were treated with a single visual internal urethrotomy and there was 1 (2.5%) urethrocutaneous fistula. All children had excellent cosmetic and functional outcomes. A staged approach allows for cosmetic reconstruction of the glans and mucosal collar during stage 1 and offers 2 opportunities to augment penile size with testosterone. Bladder or buccal mucosal grafts are avoided since the prepuce is always adequate. There are no hypospadias deformities, penile shaft torsion or asymmetry. Fistula formation is minimal and strictures are minor. The 2-stage repair remains a safe, reliable alternative for boys with severe hypospadias.

Intravesical instillation of gentamicin sulfate: in vitro, rat, canine, and human studies

OBJECTIVE

Intravesical instillation of gentamicin sulfate has been used empirically as prophylaxis and to treat bacilluria in spinal-cord-injured patients undergoing clean intermittent catheterization. To assess the risks of absorption and the effects of storage conditions on antimicrobial potency, a series of studies were conducted.

METHODS

Four studies were carried out: (1) An infected fulgurated rat bladder model was created to determine the effects of inflammation and infection on absorption. (2) A canine model with bilateral vesicoureteral reflux and elevated bladder pressures (> 40 cmH2O) assessed the effects of reflux and storage pressure. (3) The effects in patients with associated conditions including renal transplantation, myelomeningocele, vesicoureteral reflux, and bladder augmentation, were analyzed. (4) To determine the effects of storage conditions, solutions of gentamicin sulfate (480 mg gentamicin sulfate in 1 L 0.9% NaCl) were made that controlled for pH, storage temperature, and duration.

RESULTS

(1) Increased absorption was found in 43 percent of rat serum samples. (2) None of the dogs demonstrated measurable absorption. (3) None of the patients likewise had measurable absorption. (4) All solutions were equally potent when tested against a panel of common urinary pathogens. Storage up to two months at room temperature without alkalinization had no effect on potency.

CONCLUSIONS

Instilled intravesical gentamicin sulfate has a low risk of absorption and is highly effective. Severe bladder inflammation can increase transvesical absorption. It has prolonged stability without special storage conditions and should be considered as a route of prophylaxis in patients who perform intermittent catheterization.