Floor plate and motor neuron induction by different concentrations of the amino-terminal cleavage product of sonic hedgehog autoproteolysis

The differentiation of floor plate cells and motor neurons can be induced by Sonic hedgehog (SHH), a secreted signaling protein that undergoes autoproteolytic cleavage to generate amino- and carboxy-terminal products. We have found that both floor plate cells and motor neurons are induced by the amino-terminal cleavage product of SHH (SHH-N). The threshold concentration of SHH-N required for motor neuron induction is about 5-fold lower than that required for floor plate induction. Higher concentrations of SHH-N can induce floor plate cells at the expense of motor neuron differentiation. Our results suggest that the induction of floor plate cells and motor neurons by the notochord in vivo is mediated by exposure of neural plate cells to different concentrations of the amino-terminal product of SHH autoproteolytic cleavage.

Long-range sclerotome induction by sonic hedgehog: direct role of the amino-terminal cleavage product and modulation by the cyclic AMP signaling pathway

A long-range signal encoded by the Sonic hedgehog (Shh) gene has been implicated as the ventral patterning influence from the notochord that induces sclerotome and represses dermomyotome in somite differentiation. Long-range effects of hedgehog (hh) signaling have been suggested to result either from local induction of a secondary diffusible signal or from the direct action of the highly diffusible carboxy-terminal product of HH autoproteolytic cleavage. Here we provide evidence that the long-range somite patterning effects of SHH are instead mediated by a direct action of the amino-terminal cleavage product. We also show that pharmacological manipulations to increase the activity of cyclic AMP-dependent protein kinase A can selectively antagonize the effects of the amino-terminal cleavage product. Our results support the operation of a single evolutionarily conserved signaling pathway for both local and direct long-range inductive actions of HH family members.

Products, genetic linkage and limb patterning activity of a murine hedgehog gene

The hedgehog (hh) segmentation gene of Drosophila melanogaster encodes a secreted signaling protein that functions in the patterning of larval and adult structures. Using low stringency hybridization and degenerate PCR primers, we have isolated complete or partial hh-like sequences from a range of invertebrate species including other insects, leech and sea urchin. We have also isolated three mouse and two human DNA fragments encoding distinct hh-like sequences. Our studies have focused upon Hhg-1, a mouse gene encoding a protein with 46% amino acid identity to hh. The Hhg-1 gene, which corresponds to the previously described vhh-1 or sonic class, is expressed in the notochord, ventral neural tube, lung bud, hindgut and posterior margin of the limb bud in developing mouse embryos. By segregation analysis the Hhg-1 gene has been localized to a region in proximal chromosome 5, where two mutations affecting mouse limb development previously have been mapped. In Drosophila embryos, ubiquitous expression of the Hhg-1 gene yields effects upon gene expression and cuticle pattern similar to those observed for the Drosophila hh gene. We also find that cultured quail cells transfected with a Hhg-1 expression construct can induce digit duplications when grafted to anterior or mid-distal but not posterior borders within the developing chick limb; more proximal limb element duplications are induced exclusively by mid-distal grafts. Both in transgenic Drosophila embryos and in transfected quail cells, the Hhg-1 protein product is cleaved to yield two stable fragments from a single larger precursor. The significance of Hhg-1 genetic linkage, patterning activity and proteolytic processing in Drosophila and chick embryos is discussed.

Renal effects of CO2 insufflation: oliguria and acute renal dysfunction in a rat pneumoperitoneum model

OBJECTIVE

To determine the mechanism by which oliguria develops during raised intra-abdominal pressure secondary to CO2 insufflation, we created a rat pneumoperitoneum model.

METHODS

Male Sprague-Dawley rats (n = 67) were organized into three groups. Each group was subjected to abdominal pressures of 0 (control), 5, or 10 mm Hg, over one, two, and four hours. Fourteen additional rats underwent a two-hour period of 10 mm Hg insufflation pressure followed by desufflation to 0 mm Hg. Urine output (UO) and serum creatinine levels were measured both during insufflation at one, two, and four hours, and two, four, ten, and twenty-two hours following its release. These measurements were compared to control values at each time point. Ultrasonic flow probes placed around both the inferior vena cava (IVC) and abdominal aorta during insufflation characterized the effects of increased abdominal pressure on blood flow. The flow rate was determined at insufflation pressures of 0 (control, 100% flow) to 25 mm Hg.

RESULTS

Rats subjected to 10 mm Hg pressure had significant decreases in UO (oliguria) compared to controls for up to four hours (P < 0.01). There were no significant differences in UO in the control or 5 mm Hg groups over each time interval. While a reduction in UO was observed at two, four, and ten hours postrelease, significance was achieved only at ten hours (P < 0.006). By twenty-two hours postrelease, no differences in UO were observed. Serum creatinine elevations declined two hours postdesufflation. IVC flow was reduced by 92.9 percent at 10 mm Hg, while arterial flow decreased by 46.4 percent. Flow was restored to preinsufflation levels after release of pneumoperitoneum.

CONCLUSIONS

Oliguria can be produced in rats undergoing pneumoperitoneum. The renal effects of pneumoperitoneum are most likely related to renal vascular insufficiency from central venous compression.

Limb-patterning activity and restricted posterior localization of the amino-terminal product of Sonic hedgehog cleavage

BACKGROUND

Sonic hedgehog (Shh), a vertebrate homolog of the Drosophila segment polarity gene hedgehog (hh), has been implicated in patterning of the developing chick limb. Such a role is suggested by the restricted expression of Shh along the posterior limb bud margin, and by the observation that heterologous cells expressing Shh have limb-polarizing activity resembling that of cells from the polarizing region of the posterior limb bud margin. It has not been demonstrated, however, that the Sonic hedgehog protein (SHH) alone is sufficient for limb patterning. SHH has been shown to undergo autoproteolytic cleavage in vitro, yielding two smaller products. It is of interest, therefore, to determine whether processing of SHH occurs in the developing limb and how such processing influences the function of SHH.

RESULTS

We demonstrate that SHH is proteolytically processed in developing chick limbs. Grafts of cells expressing SHH protein variants that correspond to individual cleavage products demonstrate that the ability to induce patterned gene expression and to impose morphological pattern upon the limb bud is limited to the amino-terminal product (SHH-N) of SHH proteolytic cleavage. We also demonstrate that bacterially synthesized and purified SHH-N, released from implanted beads, is sufficient for limb-patterning activity. Finally, we show that the endogenous amino-terminal cleavage product is tightly localized to the posterior margin of the limb bud.

CONCLUSIONS

Our data show that, of the two cleavage products resulting from SHH autoproteolysis, SHH-N expressed in grafted heterologous cells or supplied in purified form is sufficient to impose pattern upon the developing limb. Moreover, the restricted localization of the endogenous amino-terminal SHH cleavage product to the posterior border of the chick limb bud makes it unlikely that its patterning activity results from it being distributed in a broad gradient across the antero-posterior axis. More consistent with the observed localization is a model in which the amino-terminal SHH cleavage product exerts its patterning effects by local induction in or near the polarizing region, initiating a cascade of gene expression that ultimately extends across the developing limb.

Rapid reduction in blood flow to the rat ventral prostate gland after castration: preliminary evidence that androgens influence prostate size by regulating blood flow to the prostate gland and prostatic endothelial cell survival

BACKGROUND

Androgenic steroids regulate the development and size of the mammalian prostate gland. The mechanism(s) for this growth control might involve a direct effect on prostate cell proliferation and survival as well as more complex effects on the tissue environment supporting nourishment and oxygenation. In this study, we evaluated an animal model of androgen action on the prostate, the rat ventral prostate gland, to determine whether acute androgen withdrawal, by means of castration, might alter the primary blood flow to the prostate gland and for the effects of castration on prostatic endothelial cell viability.

METHODS

Groups of rats studied included intact control males, males that had been surgically castrated, or males that received a sham-surgical castration. Relative blood flow (RBF) to the rat ventral prostate glands and rat bladders were measured at 18 and 24 hr after castration or sham castration using a fluorescent microsphere infusion technique. Thin sections from fixed and embedded rat ventral prostate glands obtained from unoperated or 12-hr castrated rats were analyzed by the TUNEL immunostaining technique to microscopically identify and quantify apoptotic epithelial, stromal, and endothelial cells.

RESULTS

RBF to the rat ventral prostate was reduced by 38%, at 18 hr after castration when compared with intact or sham-operated rats and by 45% at 24 hr after castration (P=0.038 unoperated/0.025 sham operated). In contrast, RBF to the bladder was not significantly different between any of the groups in the 24-hr castrate experiment. TUNEL staining analysis of ventral prostate tissues obtained from 12-hr castrated rats showed only rare TUNEL-positive epithelial cells similar to the control tissue but significantly increased TUNEL labeling for endothelial and other ventral prostate stromal cells.

CONCLUSIONS

Castration resulted in a rapid and significant reduction of blood flow to the mature rat ventral prostate gland that was not seen in the bladder. This reduction precedes the appearance of apoptosis in the epithelial cells of the tissue but more coincided with the appearance of TUNEL-positive prostate vascular endothelial and stromal cells, suggesting that androgens support the survival of cells in the vascular and stromal compartment of the rat prostate as well as in the prostatic epithelium. These preliminary data support the concept that androgen action on the prostate might involve primary regulation of prostate blood flow and prostate vascular cell vitality.

Oliguria during laparoscopic surgery

Oliguria is infrequently viewed as a complication of laparoscopic surgery. The rate of urine output in six healthy patients undergoing laparoscopic surgery was measured during the period of CO2 pneumoperitoneum and for several hours after desufflation. The average hourly urine output during insufflation was 0.30 +/- 0.14 mL/kg despite an average hourly intravenous infusion rate of lactated Ringer's solution of 13.0 +/- 4.0 mL/kg. After release of pneumoperitoneum, urine output increased 467% to 1.7 +/- 1.1 mL/kg per hour. Patients remained hemodynamically unchanged perioperatively. Preoperative and postoperative blood urea nitrogen and creatinine concentrations did not significantly differ. We discuss the potential etiologic factors in the development of oliguria in the setting of the increased intra-abdominal pressure of pneumoperitoneum and the implications of this acute but reversible renal dysfunction.

Laser tissue soldering in urinary tract reconstruction: first human experience

OBJECTIVES

Laser tissue soldering (LTS) in the urinary tract provides an immediate leak-free seal and may avoid complications seen with conventional repair (such as fistula and stricture). We have begun a Phase I clinical trial investigating the use of LTS in performing urologic reconstructive surgery.

METHODS

Ten patients (aged 3 months to 38 years) underwent urologic reconstruction using LTS with a protein solder composed of human albumin (42%) and indocyanine green dye. In each case standard microsuture repair preceded laser-soldered suture line reinforcement. Anastomotic closure time and immediate leak pressure were measured. Postoperatively, all patients were evaluated for evidence of complications, including stricture, fistula formation, or impaired healing.

RESULTS

Using LTS as an adjunct to suturing added an average of 7.9 +/- 3.0 minutes (28%) to the overall mean anastomotic time of 28.3 +/- 9.4 minutes. Intraoperative leak pressure measurements for laser-soldered anastomoses (> or = 94.2 +/- 24.2 mm Hg) were significantly higher (P < 0.001) than primarily sutured anastomoses (20 +/- 2.9 mm Hg). Two instances of suture disruption (20%) occurred during laser activation, neither of which were repaired with sutures. Average follow-up for all patients was 7.1 + - 2.2 months. There were no intraoperative or postoperative complications, including the 2 patients with suture disruption.

CONCLUSIONS

These initial clinical results indicate that LTS is safe, easy to perform, and, contrary to conventional suturing, provides an immediate leak-free closure. Follow-up in these and other patients, as well as those undergoing sutureless and stent-free procedures, will determine whether our method of LTS benefits patients undergoing urologic reconstruction.

Development of a consumer product ingredient database for chemical exposure screening and prioritization

Consumer products are a primary source of chemical exposures, yet little structured information is available on the chemical ingredients of these products and the concentrations at which ingredients are present. To address this data gap, we created a database of chemicals in consumer products using product Material Safety Data Sheets (MSDSs) publicly provided by a large retailer. The resulting database represents 1797 unique chemicals mapped to 8921 consumer products and a hierarchy of 353 consumer product "use categories" within a total of 15 top-level categories. We examine the utility of this database and discuss ways in which it will support (i) exposure screening and prioritization, (ii) generic or framework formulations for several indoor/consumer product exposure modeling initiatives, (iii) candidate chemical selection for monitoring near field exposure from proximal sources, and (iv) as activity tracers or ubiquitous exposure sources using "chemical space" map analyses. Chemicals present at high concentrations and across multiple consumer products and use categories that hold high exposure potential are identified. Our database is publicly available to serve regulators, retailers, manufacturers, and the public for predictive screening of chemicals in new and existing consumer products on the basis of exposure and risk.

The Malone antegrade continence enema procedure in the management of patients with spina bifida

BACKGROUND

In patients with spina bifida, traditional bowel management programs such as suppositories, retrograde enemas, and manual disimpaction have been largely unsatisfactory. The Malone antegrade continence enema (ACE) procedure has largely changed our approach to bowel management in this patient group.

STUDY DESIGN

Over a 3-year period between January 1994 and January 1997, 27 patients with spina bifida underwent the Malone ACE procedure at our institutions. At the time of their ACE procedure, four patients underwent simultaneous continent urinary diversion and three had simultaneous small-bowel bladder augmentation. All the patients were evaluated for 9 months or more after their procedure, and 10 of the patients have been followed for more than 2 years.

RESULTS

Postoperatively, predictable bowel control and continence were achieved in 19 of the 27 patients, but 6 had some rectal soiling requiring a sanitary pad. All patients were out of diapers and none reported stomal leakage. Eighteen of the 27 patients were able to manage independently and 9 required assistance. Two patients had stopped using their ACE stoma despite good technical results. The appendix was used as a catheterizable stoma in 15 of the 27 patients. The appendix was not available in 12 patients, so a tubularized cecal flap was used in 9 and a small-bowel neoappendix was created in 3. Complications included stomal stenosis in 5 patients, cecal-flap necrosis in 1, and stomal granulations in 3.

CONCLUSIONS

We believe that the ACE procedure provides reliable colonic emptying and avoids fecal soiling in the majority of individuals, and we find it widely and enthusiastically accepted by patients with spina bifida.

Esophageal tolerance to high-dose stereotactic ablative radiotherapy

Dose-volume parameters are needed to guide the safe administration of stereotactic ablative radiotherapy (SABR). We report on esophageal tolerance to high-dose hypofractionated radiation in patients treated with SABR. Thirty-one patients with spine or lung tumors received single- or multiple-fraction SABR to targets less than 1 cm from the esophagus. End points evaluated include D(5cc) (minimum dose in Gy to 5 cm(3) of the esophagus receiving the highest dose), D(2cc) , D(1cc) , and D(max) (maximum dose to 0.01 cm(3) ). Multiple-fraction treatments were correlated using the linear quadratic and linear quadratic-linear/universal survival models. Three esophageal toxicity events occurred, including esophagitis (grade 2), tracheoesophageal fistula (grade 4-5), and esophageal perforation (grade 4-5). Chemotherapy was a cofactor in the high-grade events. The median time to development of esophageal toxicity was 4.1 months (range 0.6-6.1 months). Two of the three events occurred below a published D(5cc) threshold, all three were below a D(2cc) threshold, and one was below a D(max) threshold. We report a dosimetric analysis of incidental dose to the esophagus from SABR. High-dose hypofractionated radiotherapy led to a number of high-grade esophageal adverse events, suggesting that conservative parameters to protect the esophagus are necessary when SABR is used, especially in the setting of chemotherapy or prior radiotherapy.

Vaginal reconstruction

Absence of the vagina presents a challenging problem for the reconstructive urologist. This article reviews the pertinent diagnostic and pretreatment considerations and the surgical options, in particular, bowel vaginoplasty, for these patients.

Effects of platelet-derived growth factor and fibroblast growth factor on free intracellular calcium and mitogenesis

Although increased free intracellular calcium (Cai) may be one of the main regulators of cell growth and differentiation, studies in cell populations have implied that not all growth factors produce Cai increases. In order to examine in more detail whether Cai increases were related to mitogenesis, we used digital image analysis of intracellular Fura-2 fluorescence to measure Cai in individual BALB/c 3T3 cells stimulated with either platelet-derived growth factor (PDGF) or fibroblast growth factor (FGF). We found that PDGF induced larger and more prolonged Cai increases than FGF did, but that both growth factors induced an initial rapid increase in Cai (less than 2 min) followed by a later sustained increase (greater than 20 min). Only the prolonged Cai increase required extracellular calcium. Following PDGF treatment (1-8 units/ml), the percentage of cells with a large peak Cai increase (greater than twofold) correlated with the percentage of cells made competent (subsequent growth in 1% platelet-poor-plasma). In contrast, purified bovine basic FGF (200-800 pg/ml) and recombinant human acidic FGF (10-300 ng/ml) produced peak Cai increases that were not directly correlated with mitogenesis. In addition, concentrations of intracellular Quin 2 that inhibited Cai transients also inhibited PDGF stimulation but not FGF stimulation of mitogenesis. Thus, Cai increases are necessary for mitogenesis in BALB/c 3T3 cells stimulated by PDGF, but not that stimulated by FGF.

Hypospadias repair by laser tissue soldering: intraoperative results and follow-up in 30 children

OBJECTIVES

We examined the use of laser tissue soldering (LTS) as an adjunct to suturing of, as well as a primary means of, tissue closure in urethral reconstruction.

METHODS

Since June 1994, 26 boys ranging in age from 3 months to 14 years (mean 3.0 years) underwent hypospadias repair using LTS techniques. The classification of hypospadias was subcoronal in 13, midpenile in 5, penoscrotal in 7, and scrotal in 1. Laser tissue soldering was used in an additional 4 patients: tunica vaginalis patch graft corporoplasty in 2 (scrotal hypospadias), epispadias fistulae in 1, and urethral diverticulum in 1. Of these cases, 3 hypospadias repairs were completely sutureless. An intraoperative comparision was made between suturing and LTS with respect to operative time and degree of difficulty in performing LTS. Postoperatively, patients were examined to determine complications, including stricture, fistula, or impaired wound healing. An unselected group of 25 consecutive boys undergoing hypospadias repair between 1991 and 1992 served as a historical control group.

RESULTS

No intraoperative complications resulted from laser activation. In 5 of the 30 procedures (16.6%), suture disruption was noted to occur, with a higher incidence seen with finer, dyed suture material. For hypospadias repair, the average time to suture was 6.7 min/cm (n = 23), whereas it was 3.1 min/cm for adjunctive LTS (n = 23) and 1.4 min/cm for sutureless urethroplasty (n = 3). Follow-up ranged from 3 to 22 months (average 9.6). Four fistulae were noted (1 onlay, 2 skin tube grafts, 1 Thiersch tube) each following penoscrotal or scrotal hypospadias repair; a fifth fistula developed following a traumatic catheterization in a sutureless repair. The overall complication rate in the LTS group was 19% (5 of 26) versus 24% (6 of 25) for controls, whereas that for the distal forms of hypospadias was 11% (2 of 18) and 13.6% (3 of 22), respectively.

CONCLUSIONS

Tissue soldering with laser and chromophore-doped solder is feasible, safe, and easy to perform. Laser tissue soldering may be an alternative to standard microsuture technique for hypospadias repair.

Multimodality treatment with intensity modulated radiation therapy for esophageal cancer

The objective of this study is to determine the feasibility and report the outcome of patients with locally advanced esophageal cancer treated with preoperative or definitive chemoradiotherapy (CRT) using intensity-modulated radiation therapy (IMRT). Between 2003 and 2007, 30 patients with non-cervical esophageal cancer received concurrent chemotherapy and IMRT at Stanford University. Eighteen patients were planned for definitive CRT and 12 were planned for preoperative CRT. All patients had computed tomography-based treatment planning and received IMRT. The median dose delivered was 50.4 Gy. Patients planned for preoperative CRT underwent surgery 4-13 weeks (median 8.3 weeks) following completion of CRT. Median follow-up of surviving patients from start of RT was 24.2 months (range 8.2-38.3 months). The majority of tumors were adenocarcinomas (67%) and poorly differentiated (57%). Tumor location was 7% upper, 20% mid, 47% lower, and 27% gastroesophageal junction. Actuarial 2-year local-regional control (LRC) was 64%. High tumor grade was an adverse prognostic factor for LRC and overall survival (OS) (P= 0.015 and 0.012, respectively). The 2-year LRC was 83% vs. 51% for patients treated preoperatively vs. definitively (P= 0.32). The 2-year disease-free and OS were 38% and 56%, respectively. Twelve patients (40%) required feeding tube placement, and the average weight loss from baseline was 4.8%. Twelve (40%) patients experienced grade 3+ acute complications and one patient died of complications following feeding tube placement. Three patients (10%) required a treatment break. Eight patients (27%) experienced grade 3 late complications. No grade 4 complications were seen. IMRT was effective and well tolerated. Disease recurrence remains a challenge and further investigation with dose escalation to improve LRC and OS is warranted.

Testicular microlithiasis in a child with torsion of the appendix testis

We report on an 8-year-old boy with a unilateral testicular mass and bilateral diffusely echogenic testes on sonography. At inguinal exploration torsion of an appendix testis with a reactive phlegmon was found and testis biopsy revealed significant testicular microlithiasis. To our knowledge our case demonstrates a previously undescribed presentation of testicular microlithiasis. The literature is reviewed and this disease entity is discussed.

Overexpression of a Rrp1 transgene reduces the somatic mutation and recombination frequency induced by oxidative DNA damage in Drosophila melanogaster

Recombination repair protein 1 (Rrp1) includes a C-terminal region homologous to several DNA repair proteins, including Escherichia coli exonuclease III and human APE, that repair oxidative and alkylation damage to DNA. The nuclease activities of Rrp1 include apurinic/apyrimidinic endonuclease, 3'-phosphodiesterase, 3'-phosphatase, and 3'-exonuclease. As shown previously, the C-terminal nuclease region of Rrp1 is sufficient to repair oxidative- and alkylation-induced DNA damage in repair-deficient E. coli mutants. DNA strand-transfer and single-stranded DNA renaturation activities are associated with the unique N-terminal region of Rrp1, which suggests possible additional functions that include recombinational repair or homologous recombination. By using the Drosophila w/w+ mosaic eye system, which detects loss of heterozygosity as changes in eye pigmentation, somatic mutation and recombination frequencies were determined in transgenic flies overexpressing wild-type Rrp1 protein from a heat-shock-inducible transgene. A large decrease in mosaic clone frequency is observed when Rrp1 overexpression precedes treatment with gamma-rays, bleomycin, or paraquat. In contrast, Rrp1 overexpression does not alter the spot frequency after treatment with the alkylating agents methyl methanesulfonate or methyl nitrosourea. A reduction in mosaic clone frequency depends on the expression of the Rrp1 transgene and on the nature of the induced DNA damage. These data suggest a lesion-specific involvement of Rrp1 in the repair of oxidative DNA damage.

Features of tropospheric and stratospheric dust

A series of 119 profiles obtained over New Mexico comprise aerosol attenuation coefficients vs altitude to about 35 km. These profiles show the existence of several features. A surface convective dust layer extending up to about 5 km is seasonally dependent. Also, a turbidity maximum exists below the tropopause. The altitude of an aerosol maximum in the lower stratosphere is located just below that of the minimum temperature. The colder the minimum temperature, the greater is the aerosol content of the layer. This relationship suggests that the 20-km dust layer is due to convection in tropical air and advection to higher latitudes. Computed averages of optical thickness show that abatement of stratospheric dust from the Mt. Agung eruption became evident in April 1964. Results based on seventy-nine profiles characterizing volcanic dust abatement indicate that above 26 km, the aerosol scale height averages 3.75 km. Extrapolating with this scale height, tabulations are developed for uv, visible, and ir attenuation to 50 km. Optical mixing ratios are used to examine the aerosol concentrations at various altitudes, including a layer at 26 km having an optical thickness 10(-3) for 0.55-micro wavelength.

Distinct and shared three-dimensional chromosome organization patterns in lymphocytes, monoclonal gammopathy of undetermined significance and multiple myeloma

The consistent appearance of specific chromosomal translocations in multiple myeloma has suggested that the positioning of chromosomes in the interphase nucleus might play a role in the occurrence of particular chromosomal rearrangements associated with malignant transformation. Using fluorescence in situ hybridization, we have determined the positions of selected chromosome pairs (18 and 19, 9 and 22, 4 and 14, 14 and 16, 11 and 14) in interphase nuclei of myeloma cells compared to normal lymphocytes of treatment-naïve patients. All chromosome pairs were arranged in a nonrandom pattern. Chromosomes commonly involved in myeloma-associated translocations (4 and 14, 14 and 16, 11 and 14) were found in close spatial proximity, and this is correlated with the occurrence of overlapping chromosome territories. The spatial distribution of chromosomes may increase the possibility of chromosomal translocations in multiple myeloma.

Laser welding with albumin-based solder: experimental full-tubed skin graft urethroplasty

BACKGROUND AND OBJECTIVES

Fistula and stricture formation at the site of sutured anastomoses are frequent complications of major urethroplasty. We performed urethroplasty using laser-welded skin tube grafts in the hope that in addition to being free of suture holes, grafts would be as strong as or stronger than sutured controls.

STUDY DESIGN/MATERIAL AND METHODS

Scrotal skin was harvested from each of 11 rabbits and fashioned into tubes 3-4 cm in length using either conventional suture techniques or laser welding. Welding was performed using an 808-nm diode laser and a dye-enhanced solder composed of albumin and sodium hyaluronate. Laser power density was 15.9 watts/cm2. For each graft, leak pressure, and urethroplasty time (tube creation and anastomosis to native urethra) were measured.

RESULTS

Urethroplasty time was significantly shorter and initial leak pressures were seven times greater in the laser-welded group.

CONCLUSIONS

The near-uniform occurrence of strictures in both groups suggests that the rabbit is not an ideal model for free tube graft urethroplasty. However, our data indicate that laser welding with albumin-based solder, when used in the appropriate setting, may offer the potential for the rapid creation of watertight grafts in reconstructive urology.

Reconstructive surgery for children with pelvic rhabdomyosarcoma

Rhabdomyosarcoma is the most common soft-tissue sarcoma found in children and can arise almost anywhere skeletal muscle is found. It represents 4% to 8% of malignant solid tumors in children, ranking behind central nervous system tumors, lymphoma, neuroblastoma, and Wilms' tumor. Reconstructive surgery has become an integral part of the total plan in patients undergoing radical surgery for rhabdomyosarcoma. Advances in surgical techniques can often provide a reasonable lifestyle for patients.

Initial ATP Formation, NADP Reduction, CO(2) Fixation, and Chloroplast Flattening Upon Illuminating Pea Leaves

Chloroplasts in living cells of detached and sectioned leaves of Pisum sativum had a thickness of 2.68 +/- 0.04 mu in the dark as determined from photographs made using a phase contrast microscope. Upon illumination with 4000 lux for 10 min, the chloroplasts flattened to 2.15 +/- 0.04 mu. There was a short lag period of about 11 sec at 1000 lux and 2 sec at 4000 lux before appreciable light-induced flattening occurred. Both ATP and reduced nicotinamide adenine dinucleotide phosphate (NADPH) in detached pea leaves increased upon illumination and then fell during the initial 60 sec. The maximum ATP level was attained in 16 sec at 1000 lux and 10 sec at 4000 lux, while NADPH required about twice as long to reach a maximum. A sustained rate of carbon dioxide fixation occurred after a lag period coinciding in time with the drop in the NADPH level. ATP appeared to be involved not only with carbon dioxide fixation, but also with some reaction beginning sooner, perhaps the light-induced chloroplast flattening. Considering the initial photophosphorylation and the sustained CO(2) fixation rates, the ATP formation rate in vivo apparently increased after the leaves had been in the light for a few min.

Effects of diode laser welding with dye-enhanced glue on tensile strength of sutures commonly used in urology

BACKGROUND AND OBJECTIVE

Tissue welding using laser-activated protein solders may soon become an alternative to sutured tissue approximation. In most cases, approximating sutures are used both to align tissue edges and provide added tensile strength. Collateral thermal injury, however, may cause disruption of tissue alignment and weaken the tensile strength of sutures. The objective of this study was to evaluate the effect of laser welding on the tensile strength of suture materials used in urologic surgery.

STUDY DESIGN/MATERIAL AND METHODS

Eleven types of sutures were exposed to diode laser energy (power density = 15.9 W/cm2) for 10, 30, and 60 seconds. Each suture was compared with and without the addition of dye-enhanced albumin-based solder. After exposure, each suture material was strained (2"/min) until ultimate breakage on a tensometer and compared to untreated sutures using ANOVA.

RESULTS

The strength of undyed sutures were not significantly affected; however, violet and green-dyed sutures were in general weakened by laser exposure in the presence of dye-enhanced glue. Laser activation of the smallest caliber, dyed sutures (7-0) in the presence of glue caused the most significant loss of tensile strength of all sutures tested.

CONCLUSION

These results indicate that the thermal effects of laser welding using our technique decrease the tensile strength of dyed sutures. A thermally resistant suture material (undyed or clear) may prevent disruption of wounds closed by laser welding techniques.

Nonobstetrical abdominal surgery during pregnancy in Women's Hospital

OBJECTIVE

To determine if nonobstetrical abdominal surgery during pregnancy in Women's Hospital at the University of Southern California School of Medicine was associated with increased rates of preterm delivery or spontaneous loss. Preoperative diagnostic accuracy was also evaluated.

METHODS

We performed a retrospective review of all cases of nonobstetrical abdominal surgery in our institution during a 7-year period from November 1991 to November 1998.

RESULTS

One hundred-six cases of nonobstetrical abdominal surgery were identified. Eighty-eight women underwent laparotomy and 18 had laparoscopic abdominal surgery. Seventy-three women had emergent surgery and 31 had elective surgery. Seventy-six percent (80/106) of subjects had the same preoperative and postoperative diagnoses. We obtained delivery data for 62 of 106 (59%) subjects. Eleven of 62 (18%) subjects who had nonobstetrical abdominal surgery during pregnancy delivered preterm (<37 weeks' gestation). This was not significantly different from the institutional preterm delivery rate of Women's Hospital (8999/56305 [16%]) (P = 0.84). Two of 106 (2%) women experienced spontaneous pregnancy loss following surgery; both occurred in the second trimester.

CONCLUSIONS

Nonobstetrical abdominal surgery during pregnancy in Women's Hospital was not associated with higher frequencies of preterm deliveries or spontaneous losses than our institutional rates.