Biomedical subjects
Publications and source records attributed to S D Smith.
This article describes the benefits of using municipal investment contracts for the reinvestment of municipal bond proceeds. It shows how municipal investment contracts may be structured to meet a borrower's objectives of liquidity, security, and maximization of investment yield. Several examples show how a custom-tailored municipal investment contract may achieve results unobtainable through traditional investment vehicles.
Expression of the multidrug resistance gene mdr1 is reported to be an important determinant of responsiveness to therapy and survival in some cancers. Many different methods have been used to evaluate mdr1 expression in these studies. This paper compares four methods for determination of mdr1 expression. We studied the mdr1 gene expression in 36 freshly established cell lines from 28 children with acute lymphoblastic leukemia (16 T-ALL, six BCP-ALL, two B-ALL (L3), two biphenotypic leukemias, two Burkitt's lymphomas). Leukemic specimens were obtained at the time of diagnosis in 16 cases, and after chemotherapy in 20 cases. In all the samples, mdr1 mRNA was measured by slot blotting and reverse transcriptase polymerase chain reaction (rt-PCR), and the presence of the mdr1 product, P-glycoprotein, was detected by immunohistochemistry with the MRK-16 monoclonal antibody. In situ mdr1 RNA hybridization was performed in 30 cases. Complete agreement was noted between all the techniques in 14 cases (39%). Results differed on a single test result in another 39% of the cases. These 78% of cases were considered assessable, and the consensus result was presumed to be correct. By this consensus criterion, immunohistochemistry yields both false negative (11%), and false positive (11%) results. RNA slot blotting has a high (21%) false positive rate. In situ mRNA hybridization and rt-PCR have the highest concordance, 80%. The 28 patients from whom these cell lines were derived appear to represent a very poor prognosis group, since there are only two patients (with Burkitt's lymphoma) who are long-term survivors. Nonetheless, a complete clinical response to therapy was correlated with absence of mdr1 expression in assessable cases (p = 0.04). These four methods of determining mdr1 expression often yield discordant results. Therefore, the use of at least two methods for evaluating mdr1 expression is advisable. Rt-PCR is recommended because of its relative simplicity and specificity. This should be supplemented by a technique (immunohistochemistry or flow cytometry) able to detect heterogeneity of P-glycoprotein expression among cells.
BACKGROUND: Bacterial translocation is a process believed to result in nosocomial infections. Secretory IgA (sIgA) may have a role in the prevention of translocation by its ability to bind and aggregate bacteria, a function termed "immune exclusion." The present study was done to determine the effect of specific binding of sIgA to bacteria on the movement of these organisms across the intact epithelial membrane. STUDY DESIGN: Bacterial translocation across intact intestinal segments of rats were assessed in vitro using the Ussing model. Secretory IgA (0.25 mg per mL) from pooled human colostrum was added to the perfused segments of ileum in the Ussing system. Subsequently, the membranes were exposed to 5 x 10(9) cfu per mL Escherichia coli on their mucosal side. A second experiment tested the effect of human IgG when perfused with E. coli using the same preparation. All experiments had paired matched rats in a control group without immunoglobulin. The ability of sIgA and IgG to bind to E. coli was studied by an in vitro assay, as well as by transmission electron microscopy and immunofluorescence of random IgA/E. coli experiments. Measurements obtained in all experimental and control groups were the incidence and amount of bacterial passage and the potential difference generated by the intestinal segments (an index of viability). RESULTS: There were no differences in potential difference between control and experimental groups in either of the two experiments. Secretory IgA bound E. coli and completely prevented passage of E. coli as compared with rats in the control group. IgG bound E. coli; however, the incidence of passage was equal to that of rats in the control group. However, the presence of IgG resulted in a significantly reduced number of bacteria that passed when compared with controls (p < 0.05). Electron microscopic studies revealed intact surface morphology and immunofluorescence revealed aggregates of IgA and E. coli on the mucosal, but not submucosal, surface of the ileal membranes. CONCLUSIONS: This study provides direct evidence of immune exclusion by sIgA. When bound to bacteria, it prevents passage across a morphologically intact segment of viable intestinal tissue.
BACKGROUND: Although gastrointestinal mucus is one of a number of putative host defense mechanisms that protect the gut barrier against microbial translocation, little experimental data are available to show its role in this process. The present study sought to determine the role of mucus depletion on the transepithelial passage of bacteria across viable segments of rat ileum mounted in Ussing chambers in vitro. METHODS: Intestinal mucus was depleted in 12 rats after injection with pilocarpine (160 mg/kg intraperitoneally) 45 minutes before intestinal harvest. The mucosal surfaces of the perfused gut segments mounted in the Ussing chamber were exposed to 5 x 10(9) CFU/ml Escherichia coli C-25. Viability was monitored by continuous measurements of the potential difference generated by the membranes. The electrical characteristics were unaltered by pilocarpine pretreatment or exposure to bacteria. RESULTS: Bacterial passage occurred in 100% of pilocarpine membranes as compared with 33.3% in controls (p < 0.05). Pilocarpine-treated membranes resulted in 19.9 +/- 7.5 mg of retrievable mucus as compared with 28.8 +/- 7.2 mg in controls (p < 0.05). Light and transmission electron microscopy revealed an intact epithelial surface in all membranes. There was a marked decrease in mucus on the surface of pilocarpine-treated membranes. CONCLUSIONS: Intestinal mucus secretion is a critical factor in the barrier function of the gut, and its depletion results in a dramatic increase in bacterial passage across the intact rat ileum.
BACKGROUND: Lymphoma presenting with skin involvement has heterogeneous morphology and rarely is seen in children. To study the pathogenesis of this disease, lymphoma cells from a child with B-cell large cell lymphoma of the skin were cultured in vitro. METHODS: Lymphoma cells cultured on a feeder layer under hypoxic conditions grew in vitro after a latency period of 2 weeks. Since interleukin-6 (IL-6) induces final differentiation of activated B-lymphocytes, the cell line was evaluated for the presence of IL-6 receptors and biologic response to IL-6. RESULTS: An Epstein-Barr virus (EBV)-negative cell line (UoC-B2) was established which expressed CD34, CD45, HLA-DR, CD19, CD20, sIgM, sIgD, and lambda light chain. Good general concordance was observed between the patient's lymphoma and the cell line by comparing the immunophenotype, genotype, and karyotype. The UoC-B2 cells expressed surface IgM but did not secrete IgM into the culture media even in the presence of supplemental IL-6. CONCLUSIONS: A B-lymphoid cell line (UoC-B2) was established from a child with primary cutaneous lymphoma. The cells expressed cell surface IgM and receptors for IL-6 but supplemental IL-6 had no effect on IgM production or cell proliferation.
Children with acute lymphoblastic leukemia (ALL) who have completed 2.5 to 3 years of initial chemotherapy have an off-therapy relapse rate of approximately 20%. In an attempt to improve the survival of children with a late bone marrow (BM) relapse (ie, occurring greater than 6 months after cessation of primary therapy), the Pediatric Oncology Group designed a randomized study to compare the efficacy of doxorubicin/prednisone and cytarabine/teniposide in a multidrug retreatment chemotherapy program. Treatment consisted of remission reinduction with vincristine, prednisone, and doxorubicin, central nervous system prophylaxis with triple intrathecal chemotherapy, and continuation therapy (for 132 weeks) with alternating cycles of oral 6-mercaptopurine/methotrexate and intravenous vincristine/cyclophosphamide. Patients received intermittent courses of either prednisone/doxorubicin (regimen 1) or teniposide/cytarabine (regimen 2) during continuation therapy and a late intensification phase with either vincristine, prednisone, and doxorubicin (regimen 1) or teniposide and cytarabine (regimen 2). One hundred two of 105 evaluable patients (97%) achieved a second complete remission. Twenty-eight of 50 patients on regimen 1 have failed compared with 28 or 52 patients on regimen 2 (log-rank analysis, P = .68), indicating that this trial was inconclusive as to which treatment regimen was superior. The overall 4-year event-free survival for children with a late BM relapse was 37% +/- 6%. Age less than 10 years at initial diagnosis (P < or = .001), white blood cell count less than 5,000/microL at relapse (P = .036) and duration of first remission greater than 54 months (P = .039) were independently associated with a more favorable outcome. While the randomized trial was inconclusive, prolonged second complete remissions were secured in more than one-third of children with a late BM relapse of ALL. The prognostic factors identified may help select children with a late BM relapse who can be successfully retreated with chemotherapy alone.
Injury to the retrohepatic veins and vena cava secondary to blunt abdominal trauma is often fatal. The purpose of this report is to describe the successful isolation and repair of retrohepatic vascular injuries without the use of median sternotomy or vena caval shunt. Two children with both hepatic vein and retrohepatic caval injuries from blunt trauma were treated by the following surgical approach: (1) bilateral subcostal incision with vertical midline extension; (2) packing of the liver and volume resuscitation with the Rapid Infusion System prior to vascular isolation; (3) isolation of the intrapericardial vena cava through a transdiaphragmatic pericardial window; (4) control of the suprarenal vena cava and porta hepatis; and (5) repair of vein lacerations with vascular occlusion and continuous saline irrigation for improved visualization despite continued venous bleeding. This approach was tolerated and allowed successful repair without shunting in these patients despite an average weight of 14 kg and the loss of 3 L and 23 L of blood, respectively. We attribute the success of this technique to rapid control of hemorrhage and volume resuscitation. This success suggests that the routine use of shunt or sternotomy is not necessary in these devastating injuries.
The improving survival of patients with severe short-bowel syndrome along with the advent of successful intestinal transplantation have accentuated the need to answer two questions. (1) Is there an intestinal length below which adaptation to full enteral nutrition can not be expected to occur? (2) How much time is necessary to complete intestinal adaptation? We reviewed the outcome of 21 infants with less than 50 cm of small intestine to answer these questions. Patients were divided into three groups based on intestinal length, regardless of ileocecal valve status: group I, < 10 cm (n = 3); group II, 10 to 30 cm (n = 11); and group III, 30 to 50 cm (n = 7). Data were collected to assess survival, incidence of adaptation, time to adaptation, and causes of mortality. Infants in group I did not achieve intestinal adaptation to full enteral nutrition. One survived and 2 died, one from varicella pneumonia and the other after intestinal transplantation. Eight of the 11 (73%) patients in group II survived and 5 of 8 (63%) survivors achieved full intestinal adaptation after a mean interval of 320 days (range, 148 to 506 days) on parenteral nutrition. Six of the seven patients (86%) in group III survived and all survivors (100%) achieved complete enteral adaptation after an average of 376 days (range, 58 to 727 days). The overall survival was 71% (15/21), but survival in patients with > 10 cm was 78%.(ABSTRACT TRUNCATED AT 250 WORDS)
To determine the optimal method of providing enteral feeding to neurologically impaired children with gastroesophageal reflux, Nissen fundoplication with simultaneous gastrostomy tube placement (NGT) was compared with anterograde percutaneous gastrojejunostomy (APGJ), a nonsurgical procedure performed under fluoroscopic guidance. The records of 112 neurologically impaired children with gastroesophageal reflux were retrospectively reviewed; 68 had undergone NGT and 44 APGJ. Follow-up data were available for 45 NGT patients (mean age, 6.4 years) and 34 APGJ patients (mean age, 7.9 years). Mean follow-up was 1.8 years in the NGT group and 2.5 years in the APGJ group. Complications resulting from either procedure were classified either as major, which included treatment failures or morbidity resulting in prolonged hospitalization, or as minor, those requiring outpatient treatment only or not directly caused by the procedure. The NGT group had a significantly higher incidence of major complications in comparison with the APGJ group (33.3% vs 11.8%, p < 0.05). Ten patients (22.2%) in the NGT group required reoperation for complications; six required a second NGT for wrap hernia, failure, and continued gastroesophageal reflux. Two patients (5.9%) in the APGJ group required surgery for complications; one of these eventually required an NGT, and the other had an intussusception that necessitated a small-bowel resection. Minor complications were more common in the APGJ group than in the NGT group (44.1% vs 6.6%); the majority of complications were related to the jejunostomy tube. Premature replacement or reinsertion of the jejunostomy tube was necessary in 14 APGJ patients (32%). The mortality rate was 8.8% in the NGT group and 5.9% in the APGJ group (p = not significant). No death occurred within 30 days of either procedure. We conclude that APGJ is a safe alternative method for feeding the neurologically impaired child with gastroesophageal reflux.
Bovine oocytes matured in vitro were stimulated by a single pulse of direct current (DC), then cultured for 0.5-6 h and evaluated by light (LM) and transmission electron microscopy (TEM). At the light microscopic level, the beginning of oocyte chromatin decondensation was first observed 3 h post-activation (14%). A well-developed pronucleus with evenly granulated nucleoplasm surrounded by nuclear membrane was found in 12, 61 and 81% oocytes at 4, 5 and 6 h post-activation, respectively. The TEM evaluation revealed that nuclear membrane vesicules were first visible at 0.5 h post-activation and became even more prominent at 1 h. Based on these observations, it is concluded that a nuclear membrane starts to form immediately after oocyte activation, while a well-developed pronucleus appears at 4-6 h.
OBJECTIVE: To study the effect of long-term extracorporeal membrane oxygenation (ECMO) support on neutrophil function. DESIGN: A prospective, clinical investigation. SETTING: A pediatric intensive care unit. PATIENTS: Four groups of patients: ECMO group 1, newborns after 1 day of ECMO support (n = 10); ECMO group 2, newborns after 5 days of ECMO support (n = 6); group 3, normal newborns (n = 20); group 4, normal adults (n = 30). INTERVENTIONS: Two mL of heparinized blood was obtained from patients in each group. A modification of the Smith and Rommel technique was used to measure neutrophil phagocytosis and killing utilizing live Candida tropicalis as the test organism. Neutrophils were incubated for 90 mins in normal adult serum with live Candida. Viability of Candida after phagocytosis was tested by vital fluorochrome staining. Phagocytic index (the number of neutrophils with intracytoplasmic Candida divided by the total neutrophils) and candidicidal ratio (neutrophils with dead Candida divided by total neutrophils with Candida) were determined daily. MEASUREMENTS AND MAIN RESULTS: Neutrophils from ECMO group 1 (day 1) and ECMO group 2 (day 5) patients had significantly higher phagocytosis indices (72.8 +/- 20 and 76 +/- 18) and candidicidal ratios (0.15 +/- 0.1 and 0.16 +/- 0.09) compared with neutrophils from group 3 patients (normal neonates) (64 +/- 7 and 0.06 +/- 0.04). The phagocytosis indices were significantly lower in neutrophils from ECMO group 1 (day 1) and ECMO group 2 (day 5) patients compared with group 4 (adults) patients (86 +/- 9). However, the candidicidal ratios in neutrophils from ECMO groups 1 and 2 (ECMO day 1 and day 5) patients were equal to that value in group 4 (adults) (0.10 +/- 0.04). ECMO support for 5 days (ECMO group 2 vs. group 1) did not significantly change either the phagocytosis index or candidicidal ratio. CONCLUSIONS: Phagocytosis and intracellular killing by neutrophils of ECMO-supported neonates were significantly greater than those values found in normal newborns. ECMO support for 5 days produced no significant changes in neutrophil phagocytosis or killing.
The cases of seven children treated from 1980 through 1991 with blunt renal artery injuries were reviewed to determine (1) if computed tomography alone could eliminate the need for intravenous pyelography (IVP) or arteriography (ART); and (2) the causes of management delays. The diagnosis of arterial occlusion was suggested by the lack of renal contrast enhancement in six patients with CT scans and in two patients with IVP. In three patients ART was merely confirmatory. The diagnosis was suggested by IVP or CT scan within a mean of 4.7 hours of injury, but ART added an additional mean 2.3 hours to the diagnostic workup. There was an additional 3.9-hour average delay in the operating room before revascularization. Six patients underwent revascularization. Four had minimal function by postoperative renal scans. Renal artery occlusion is rapidly detected by contrast-enhanced CT scanning without IVP or ART. The time period from diagnosis to revascularization must be expedited to improve renal outcome.
Although it has been suggested that selective decontamination of the digestive tract (SDD) decreases postoperative aerobic Gram-negative and fungal infections in orthotopic liver transplantation (OLT), no controlled trials exist in pediatric patients. This prospective, randomized controlled study of 36 pediatric OLT patients examines the effect of short-term SDD on postoperative infection and digestive tract flora. Patients were randomized into two groups. The control group received perioperative parenteral antibiotics only. The SDD group received in addition polymyxin E, tobramycin, and amphotericin B enterally and by oropharyngeal swab postoperatively until oral intake was tolerated (6 +/- 4 days). Indications for operation, preoperative status, age, and intensive care unit and hospital length of stay were no different in SDD (n = 18) and control (n = 18) groups. A total of 14 Gram-negative infections (intraabdominal abscess 7, septicemia 5, pneumonia 1, urinary tract 1) developed in the 36 patients studied. Mortality was not significantly different in the two groups. However, there were significantly fewer patients with Gram-negative infections in the SDD group: 3/18 patients (11%) vs. 11/18 patients (50%) in the control group, P < 0.001. There was also significant reduction in aerobic Gram-negative flora in the stool and pharynx in patients receiving SDD. Gram-positive and anaerobic organisms were unaffected. We conclude that short-term postoperative SDD significantly reduces Gram-negative infections in pediatric OLT patients.
PURPOSE: To assess the efficacy and toxicity of chemotherapy and cranial radiation for the treatment of children with acute lymphoblastic leukemia (ALL) following first isolated CNS relapse. PATIENTS AND METHODS: One hundred twenty children were treated on Pediatric Oncology Group (POG) protocol 8304. All children had received prophylactic CNS therapy during their initial treatment. The treatment protocol included a four-drug reinduction and six weekly doses of triple intrathecal therapy (TIT). Cranial radiation, 24 Gy, was followed by monthly TIT. Systemic consolidation and maintenance therapy included 6-week cycles of mercaptopurine/methotrexate (6MP/MTX) and vincristine/cyclophosphamide (VCR/CTX), with randomization to intervening pulses of prednisone/doxorubicin (PDN/DOX) or teniposide (VM26)/cytarabine (Ara-C) for a total of 88 weeks. RESULTS: All 120 patients achieved a second complete remission. There have been 61 protocol failures. Thirty-five patients had a bone marrow relapse, four with simultaneous CNS involvement and one with concurrent testicular leukemia. Thirteen patients had a second isolated CNS relapse, 10 a testicular relapse, and two relapsed in other sites. One patient died in remission. Overall event-free survival (EFS) at 4 years was 46% +/- 7%. The toxicity associated with this protocol was minimal except for leukoencephalopathy, which occurred in 20 (17%) patients. The treatment comparison between VM26/Ara-C or PDN/DOX pulses showed a trend toward superior EFS (P = .12) in favor of VM-26/Ara-C. CONCLUSION: To date, this represents the largest series of patients with ALL treated uniformly for an isolated CNS relapse. Since marrow relapse remains the primary site of failure, future protocols must intensify systemic therapy.
The authors present a case of bilateral middle facet talocalcaneal coalitions with peroneal spasm producing a fixed valgus heel. They introduce a corrective procedure used at the Fountain Valley Regional Hospital and Medical Center and discuss its application in podiatric surgery. Correction included resection of the synostosis and lateral opening wedge heterogenous bone graft in the calcaneus to redistribute the body's weight on the heel and centralized over the axis of the subtalar joint.
For efficient transcription from the rat ribosomal DNA (rDNA) promoter by RNA polymerase I in vitro, at least two transcription factors, rat UBF and rat SL-1, are required. Transcription cannot take place in vitro in the absence of SL-1. On the other hand, there is considerable difference of opinion concerning the necessity for UBF in in vitro transcription mediated by RNA polymerase 1, and the requirement for UBF is not clear. Mammalian cells code for UBF1 and UBF2, two forms of UBF that differ in HMG box-2, one of four HMG boxes or DNA-binding domains. We have used a monospecific antibody raised to recombinant rat UBF to determine whether UBF1 and UBF2 are required for RNA polymerase I-mediated transcription. This antibody can detect as little as 1.35 x 10(-15) moles of UBF1 or UBF2 in an immunoblot. Fractionated extracts that were competent for transcription had no detectable UBF1 or UBF2 when assayed in immunoblots with this antiserum. This evidence supports the hypothesis that UBF is not required for transcription of the rat rDNA promoter in vitro and most likely functions as an auxillary transcription factor. In addition, we have fractionated rat UBF1 from UBF2 and tested each of them in in vitro transcription assays in which the 45S or spacer rDNA promoter template is limiting. UBF1 can activate transcription from either the 45S or spacer promoter under these conditions, whereas UBF2 cannot. This implies that there is a functional difference in the transactivation of RNA polymerase I by UBF1 and UBF2 in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)
There have been many attempts to develop a theoretical explanation of the phenomena of electromagnetic field interactions with biological systems. None of the reported efforts have been entirely successful in accounting for the observed experimental results, in particular with respect to the reports of interactions between extremely low frequency (ELF) magnetic fields and biological systems at ion cyclotron resonance frequencies. The approach used in this paper starts with the Lorentz force equation, but use is made of cylindrical co-ordinates and cylindrical boundary conditions in an attempt to more closely model the walls of an ion channel. The equations of motion of an ion that result from this approach suggest that the inside shape of the channel plus the ELF magnetic fields at specific frequencies and amplitudes could act as a gate to control the movement of the ion across the cell membrane.
A t(17;19) chromosomal translocation in early B-lineage acute leukemia was shown to result in chimeric transcripts that contain sequences from the E2A basic helix-loop-helix transcription factor gene on chromosome 19, fused to sequences from a previously unidentified gene (HLF) on chromosome 17 that encodes a hepatic leukemia factor. The chimeric protein consisted of the amino-terminal transactivation domain of E2A linked to the carboxyl-terminal basic region-leucine zipper domain of HLF. HLF was normally expressed in liver and kidney, but not in lymphoid cells, and was found to be closely related to the leucine zipper-containing transcription factors DBP (albumin D-box binding protein) and TEF (thyrotroph embryonic factor), which regulate developmental stage-specific gene expression.