Biomedical subjects

Kelly A Miller

Publications and source records attributed to Kelly A Miller.

17 recordsLinked to original sources

PubMed2006

Novel endotoxin-sequestering compounds with terephthalaldehyde-bis-guanylhydrazone scaffolds.

We have shown that lipopolyamines bind to the lipid A moiety of lipopolysaccharide, a constituent of Gram-negative bacterial membranes, and neutralize its toxicity in animal models of endotoxic shock. In an effort to identify non-polyamine scaffolds with similar endotoxin-recognizing features, we had observed an unusually high frequency of hits containing guanylhydrazone scaffolds in high-throughput screens. We now describe the syntheses and preliminary structure-activity relationships in a homologous series of bis-guanylhydrazone compounds decorated with hydrophobic functionalities. These first-generation compounds bind and neutralize lipopolysaccharide with a potency comparable to that of polymyxin B, a peptide antibiotic known to sequester LPS.

Animals↗

PubMed2006

Structural correlates of antibacterial and membrane-permeabilizing activities in acylpolyamines.

A homologous series of mono- and bis-acyl polyamines with varying acyl chain lengths originally synthesized for the purpose of sequestering lipopolysaccharide were evaluated for antimicrobial activity to test the hypothesis that these bis-cationic amphipathic compounds may also bind to and permeabilize intact gram-negative bacterial membranes. Some compounds were found to possess significant antimicrobial activity, mediated via permeabilization of bacterial membranes. Structure-activity relationship studies revealed a strong dependence of the acyl chain length on antimicrobial potency and permeabilization activity. Homologated spermine, bis-acylated with C8 or C9 chains, was found to profoundly sensitize Escherichia coli to hydrophobic antibiotics such as rifampin. Nonspecific cytotoxicity is a potential drawback of these membranophilic compounds. However, the surface activity of these cationic amphipaths is strongly attenuated under physiological conditions via binding to serum albumin. Significant antibacterial activity is still retained in the presence of physiological concentrations of human serum albumin, suggesting that these compounds may serve as leads in the development of novel adjuncts to conventional antimicrobial chemotherapy.

Animals↗

PubMed2006

Anti-endotoxin agents. 3. Rapid identification of high-affinity lipopolysaccharide-binding compounds in a substituted polyamine library.

Lipopolysaccharides (LPS), otherwise termed 'endotoxins', are an integral part of the outer leaflet of the outer-membrane of Gram-negative bacteria. Lipopolysaccharides play a pivotal role in the pathogenesis of 'Septic Shock', a major cause of mortality in the critically ill patient, worldwide. The sequestration of circulatory endotoxin may be a viable therapeutic strategy for the prophylaxis and treatment of Gram-negative sepsis. We have earlier shown that the pharmacophore necessary for small molecules to bind LPS involves two protonatable cationic functions separated by about 15 A, permitting the simultaneous interaction with the negatively charged phosphates on lipid A, the toxically active center of endotoxin. In this report, screening of a multi-thousand membered polyamine library through the combined use of computational and bioassay-guided screens resulted in the discovery of two novel classes of LPS-binding agents. These are represented by the 1) spermine sulfonamides and 2) C-aryl-substituted spermine analogs. We present the selection approach, screening results, computational multivariate analyses and initial structure-activity relationship evaluation herein.

Antitoxins↗

PubMed2005

Lipopolysaccharide sequestrants: structural correlates of activity and toxicity in novel acylhomospermines.

Lipopolysaccharides (LPS), otherwise termed "endotoxins", are outer membrane constituents of Gram-negative bacteria. Lipopolysaccharides play a key role in the pathogenesis of "septic shock", a major cause of mortality in the critically ill patient. Therapeutic options aimed at limiting downstream systemic inflammatory processes by targeting lipopolysaccharide do not exist at the present time. We have defined the pharmacophore necessary for small molecules to specifically bind and neutralize LPS and, using animal models of sepsis, have shown that the sequestration of circulatory LPS by small molecules is a therapeutically viable strategy. In this paper, the interactions of a series of acylated homologated spermine compounds with LPS have been characterized. The optimal acyl chain length for effective sequestration of LPS was identified to be C(16) for the monoacyl compounds. The most promising of these compounds, 4e, binds LPS with an ED(50) of 1.37 muM. Nitric oxide production in murine J774A.1 cells, as well as TNF-alpha in human blood, is inhibited in a dose-dependent manner by 4e at concentrations orders of magnitude lower than toxic doses. Administration of 4e to d-galactosamine-sensitized mice challenged with supralethal doses of LPS provided significant protection against lethality. Potent antiendotoxic activity, low toxicity, and ease of synthesis render this class of compounds candidate endotoxin-sequestering agents of potential significant therapeutic value.

Amides↗

PubMed2005

Lysine-spermine conjugates: hydrophobic polyamine amides as potent lipopolysaccharide sequestrants.

Amides↗

PubMed2005

Functionalized dendrimers as endotoxin sponges.

Lipopolysaccharides (LPS), otherwise termed 'endotoxins', are outer-membrane constituents of Gram-negative bacteria, and play a key role in the pathogenesis of 'Septic Shock', a major cause of mortality in the critically ill patient. We had previously defined the pharmacophore necessary for small molecules to specifically bind and neutralize LPS and, using animal models of sepsis, have shown that the sequestration of circulatory LPS by small molecules is a therapeutically viable strategy. Polyamidoamine dendrimers, with the surface amines substoichiometrically derivatized with alkyl groups bind LPS with high affinity, neutralize LPS-induced inflammatory responses in vitro, and afford protection in a murine model of endotoxic shock. Dendrimers represent a new class of potentially useful compounds for the therapy of Gram-negative sepsis.

Animals↗

PubMed2005

Ischemia/reperfusion: a clinically relevant model of intestinal injury yielding systemic inflammation.

BACKGROUND/PURPOSE: Multisystem organ failure (MSOF) is a major cause of morbidity and mortality in the critically ill patient. Animal models of endotoxin-induced sepsis were used to develop therapeutic regimens, which thus far have failed in clinical trials. Because multiple etiologies of MSOF affect the intestine, the authors hypothesized that during sepsis the gut may act as a possible trigger of the inflammatory cascade. As ischemia and reperfusion of the small intestine disrupts gut barrier function, thereby activating systemic inflammatory responses, the authors evaluated a murine model of ischemia/reperfusion to investigate these systemic responses to local mucosal and epithelial injury. METHODS: C57BL/10 and Balb/c mice underwent variable amounts of gut ischemia by superior mesenteric artery occlusion. Animals were evaluated for survival as well as gross and microscopic intestinal damage. RESULTS: Maximal ischemic damage occurred in the distal jejunum and proximal ileum. More severe epithelial damage and transmural inflammation were observed in C57BL/10 mice, which correlated with a higher mortality. CONCLUSIONS: This model mimics what is observed clinically with intestinal injury resulting from a progressive ischemic insult with eventual systemic manifestations. This reproducible model of systemic inflammation elicits variable responses from genetically different animals, the results of which may lead to a better understanding of MSOF.

Animals↗

PubMed2005

Laparoscopic patch repair of diaphragmatic hernias with Surgisis.

BACKGROUND: Laparoscopic repair of congenital diaphragmatic hernias has been sparsely reported. Moreover, each report has primarily been a single operative case. In most of the reports, prosthetic mesh has not been used, and when used, it has been nonabsorbable in nature. Most of these case reports have documented only a few months of clinical follow-up. METHODS: After institutional review board approval (No. 01-12-115X), the clinical course and outcome of 3 patients undergoing laparoscopic repair of foramen of Morgagni and Bochdalek hernias using 4-ply Surgisis soft tissue graft (Cook Inc, Bloomington, Ind) were reviewed to determine if this approach is appropriate. RESULTS: In 2001, 2 patients, ages 9 months and 14 years, underwent laparoscopic foramen of Morgagni repair and one 5-day-old underwent laparoscopic foramen of Bochdalek repair using Surgisis soft tissue graft as a patch to close the diaphragmatic defects because there was too much tension with primary repair. In each case, the prosthesis was secured to the rim of the defect using interrupted silk sutures tied intracorporally. The mean operative time for repair of the Morgagni defects was 230 minutes with a postoperative discharge of 1 and 2 days. For the foramen of Bochdalek repair, the operative time was 204 minutes, and the patient was discharged at 3 weeks. No complications have occurred during or after any of the procedures, but the oldest patient underwent diagnostic laparoscopy 3 months postoperatively for a radiographic finding of suspected recurrence. At laparoscopy, the patch was intact, and no diaphragmatic hernia was noted. CONCLUSIONS: Laparoscopic repair of congenital diaphragmatic defects using prosthetic material is possible although the operative time required is around 3.5 hours. Because of the brief postoperative course, the laparoscopic approach appears justified in the nonneonatal patients. Whether this approach is appropriate for repair of neonatal Bochdalek hernias remains unclear.

Absorbable Implants↗

PubMed2004

The parental perspective regarding the contralateral inguinal region in a child with a known unilateral inguinal hernia.

PURPOSE: The management of the contralateral region in a child with a known inguinal hernia has been debated by surgeons for more than 50 years. However, the perspective of the child's parents has not been sought, and this study was designed to evaluate parental views on this topic. METHODS: After IRB approval, all patients less than 10 years of age with a unilateral inguinal hernia seen by the senior surgeon were studied prospectively from November 2001 through February 2003. A study sheet was given to the parents about the nature of an inguinal hernia, the incidence of 20% to 40% of a contralateral patent processus vaginalis (CPPV), and the possible surgical options (perform repair of the unilateral inguinal hernia only, repair the unilateral inguinal hernia with contralateral exploration and repair if indicated, or unilateral inguinal hernia repair with laparoscopy through the ipsilateral hernia sac and repair of a CPPV if discovered). The parents of the last 113 patients requesting contralateral inspection were asked their motives (convenience or anesthesia concerns) regarding their decision. RESULTS: One hundred sixty-seven patients comprise the study group. Twelve parents chose unilateral repair alone, 13 chose bilateral incisions with contralateral repair if a CPPV was found, and 142 chose unilateral hernia repair with laparoscopic contralateral inspection followed by repair if needed. Regarding their motives, 90 of the last 113 parents requesting contralateral inspection indicated that convenience was the primary motive. Surprisingly, only 21 exhibited concerns about their child undergoing a second anesthesia. CONCLUSIONS: When presented options regarding management of a unilateral inguinal hernia, parents preferred laparoscopic inspection and repair of the contralateral region, if needed, more for convenience than for concerns about a second procedure and anesthesia.

Anesthesia↗

PubMed2004

Anti-endotoxin agents. 2. Pilot high-throughput screening for novel lipopolysaccharide-recognizing motifs in small molecules.

Lipopolysaccharides (LPS), otherwise termed 'endotoxins', are an integral part of the outer leaflet of the outer-membrane of Gram-negative bacteria. Lipopolysaccharides play a pivotal role in the pathogenesis of 'Septic Shock', a major cause of mortality in the critically ill patient, worldwide. The sequestration of circulatory endotoxin may be a viable therapeutic strategy for the prophylaxis and treatment of Gram-negative sepsis. We have earlier shown that the pharmacophore necessary for small molecules to bind LPS is simple, comprising of two protonatable cationic functions separated by about 15 A, permitting the simultaneous interaction with the negatively charged phosphates on lipid A, the toxically active center of endotoxin. In this report, we employ high-throughput screening methods, using a novel fluorescent probe displacement method. Searches in three-dimensional structure databases yielded about approximately 4000 commercially available small molecules, each possessing two cationic functions spaced approximately 15 A apart. Approximately 400 such compounds have been screened in an effort to validate the method by which high-affinity endotoxin binders can be identified. We show that the IC50 values that are obtained from the fluorescence-based primary screen are correlated both to the enthalpy of binding, as measured by isothermal titration calorimetry, as well as to biological potency in vitro assays. By performing rapid toxicity screens in tandem with the bioassays, lead compounds of interest can be easily identified for further systematic structural modifications and SAR studies.

Calorimetry↗

PubMed2004

Anti-endotoxin agents. 1. Development of a fluorescent probe displacement method optimized for the rapid identification of lipopolysaccharide-binding agents.

Lipopolysaccharides (LPS), otherwise termed 'endotoxins', are outer-membrane constituents of Gram-negative bacteria. Lipopolysaccharides play a key role in the pathogenesis of 'Septic Shock', a major cause of mortality in the critically ill patient. Therapeutic options aimed at limiting downstream systemic inflammatory processes by targeting lipopolysaccharide do not exist at the present time. We have defined the pharmacophore necessary for small molecules to specifically bind and neutralize LPS, and have shown using animal models of sepsis that the sequestration of circulatory LPS by small molecules is a therapeutically viable strategy. Assays reported previously in the literature do not lend themselves well to the rapid screening of large numbers of structurally diverse compounds. In this report, we describe a highly sensitive and robust fluorescent displacement assay using BODIPY TR cadaverine (BC), which binds specifically to the toxic center of LPS, lipid A, and is competitively displaced by compounds displaying an affinity for lipid A. The assay clearly discriminates subtle differences in the binding of polymyxin B, and its nonapeptide derivative, with LPS. The spectral properties of the BODIPY fluorophore are ideally suited for screening diverse structural classes of compounds, including those with conjugated aromatic groups, or with chromophores in the 260-500 nm range. The fluorescent probe: LPS complex is stable under physiologically relevant salt concentrations, resulting in the rapid rejection of spurious binders interacting via non-specific electrostatic interactions, and, therefore, in greatly improved dispersion of ED(50)values.

Acute-Phase Proteins↗

PubMed2003

Necrotizing enterocolitis in full-term infants.

OBJECTIVES: Although necrotizing enterocolitis (NEC) is primarily a disease of prematurity, full-term infants account for approximately 10% of cases. Previous studies have reported conflicting results regarding NEC in full-term (FT) versus preterm (PT) infants. A review of all infants diagnosed with NEC at our institution over the past 3 decades was performed to identify factors associated with this disease in full-term neonates. METHODS: The charts of all infants with definitive NEC from January 1, 1972 through January 1, 2001 were reviewed. Two hundred seventy-seven patients made up the study group: 251 PT and 26 FT infants. Data regarding demographics, clinical presentation, management, outcome, and other variables were collected. FT and PT infants were compared. RESULTS: Mean gestational age and birth weight in the FT group were 39.3 weeks and 3,132 g versus 30.2 weeks and 1,396 g for PT infants. Apgar scores were similar. Mean age at diagnosis was 5 days in FT versus 13 days in PT neonates (P <.001). Enteral nutrition was initiated earlier in FT infants (1.6 days v 3.1 days; P <.001), and FT infants were discharged an average of 14 days earlier than PT infants (P value not significant). Factors predisposing to NEC were found in 62% (16 of 26) of patients-heart disease in 6 infants and other conditions in 10 patients. Cardiac disease was found significantly more often (23% v 10%; P =.027) in FT infants. Survival rate was 65% (17 of 26) in the FT group versus 69% (173 of 251) in the PT infants (P value not significant). CONCLUSIONS: FT infants with NEC differ from their PT counterparts in several distinct ways. FT neonates had NEC at a significantly earlier age, perhaps owing to earlier initiation of feeding. There was a correlation between age at which feeding was begun and age of onset of NEC. Additionally, an association between cardiac disease and development of NEC in term infants was shown. Predisposing factors were present in a majority of FT infants. In contrast to other reports, the outcome of NEC in full-term infants was no better than for PT infants.

Age of Onset↗

PubMed2003

Single cannula technique and robotic telescopic assistance in infants and children who require laparoscopic Nissen fundoplication.

BACKGROUND/PURPOSE: Laparoscopic Nissen fundoplication (LNF) is being utilized more extensively in the management of symptomatic gastroesophageal reflux disease in infants and children. The traditional approach utilizes 5 3- to 5-mm cannulas for telescope and instrument access to the peritoneal cavity. The purpose of this study is to report the technique and document the results using a single 5-mm umbilical cannula for LNF, stab incisions for placement of the instruments, and robotic telescope assistance. METHODS: From November 1999 through March 2002, 154 patients underwent LNF by the senior author for pathologic gastroesophageal reflux disease. All operations were performed with a single 5-mm umbilical cannula through which a 4- or 5-mm telescope was placed for operative visualization. Four stab incisions were made through the upper/lateral abdominal wall under direct visualization avoiding the epigastric vessels. Through these stab incisions, instruments were inserted into the peritoneal cavity. The maximum insufflation pressure was 15 mm Hg in all cases. The ability to perform the procedure in the absence of additional operative cannula placement, complications during instrument insertion, the ability to maintain adequate pneumoperitoneum, the patient's age, weight, operating time, and the addition of a gastrostomy were recorded. RESULTS: All but one of the 154 LNFs were completed successfully using this technique. The mean age at operation and mean operating time was 23.9 months (range, 3 weeks to 180 months) and 91 minutes (31 to 160 minutes), respectively. Patients weight ranged from 2.4 to 57 kg (mean, 10.4 kg). Gastrostomies were placed in 52 cases. There were no complications associated with the stab incisions or insertion of the operative instruments through the abdominal wall. Pneumoperitoneum was maintained adequately in all cases. CONCLUSIONS: LNF can be performed safely and effectively with a single umbilical cannula. We recommend its use for pediatric patients who require LNF.

Adolescent↗

PubMed2002

IL-10 is not protective in intestinal ischemia reperfusion injury.

BACKGROUND: Ischemia/reperfusion of the small intestine disrupts gut barrier function, increases bacterial translocation, and activates systemic pro-inflammatory responses. Pharmacological treatment with the anti-inflammatory cytokine interleukin-10 (IL-10) following ischemia to muscle reduces the severity of local and systemic inflammation. While endogenous IL-10 is protective in murine models of acute endotoxemia, its physiological role during direct gut injury is unknown. PATIENTS AND MATERIALS: Mice genetically deficient in IL-10 (IL-10(-/-)) and their normal littermates (IL-10(+/+)) underwent 20 to 50 min of gut ischemia by occlusion of the superior mesenteric artery. RESULTS: Both short- and long-term (>16 h) survival after reperfusion of IL-10(-/-) mice was identical to that of the wild-type littermates, with 50% mortality observed at 35 min of occlusion. The small bowel demonstrated discrete gross areas of hemorrhage and ischemia localized to the jejunum. No significant difference in the extent or time for occurrence of macroscopic or microscopic intestinal damage to the small bowel was observed in IL-10(-/-) or IL-10(+/+) mice, despite the marked elevation in serum IL-6. CONCLUSIONS: The absolute serum concentration of IL-6 in the presence or the absence of IL-10 does not affect local or systemic response to ischemic intestinal injury. These results also demonstrate that the anti-inflammatory cytokine IL-10 does not play a significant local or systemic protective role in this model of ischemia/reperfusion.

Animals↗

PubMed2002

Thyroid transcription factor-1 expression in the human neonatal tracheoesophageal fistula.

BACKGROUND/PURPOSE: Esophageal atresia with tracheoesophageal fistula (EA/TEF) is a relatively common congenital anomaly, but its pathogenesis remains poorly understood. Previous studies using the experimental Adriamycin-induced rat model of EA/TEF suggest that the fistula tract, or "distal esophagus," is derived from respiratory epithelium and expresses the respiratory-specific transcription factor TTF-1. To better correlate the experimental rat model of EA/TEF with the human anomaly, we looked for evidence of a respiratory-derived origin in the neonatal TEF. METHODS: After IRB approval, 2 human TEF samples were removed at the time of surgery. The tissue from the fistula tract was trimmed in accordance with what the surgeons deemed to be appropriate for the preparation for a primary anastomosis. The tissues then were processed for reverse transcription polymerase chain reaction (RT-PCR), histology, and immunohistochemistry. Normal embryonic lung cDNA was used for positive controls. RESULTS: Histologic examination of tissue specimens showed many epithelial tubules within loose connective tissue and a disorganized muscular coat. Thyroid transcription factor one (TTF-1) and hepatocyte nuclear factor 3beta (HNF-3beta) were shown to be present in the tissue specimen by RT-PCR and immunohistochemistry. In addition, FGF-10, a strong morphogen present in the developing lung, and FGF-1 were both present by RT-PCR. The PCR band sizes for both FGF-1 and -10 were appropriate, using human embryonic cDNA as a control, and the bands were confirmed as nongenomic by either placing the PCR primers across a known intron sequence (TTF-1) or by absence of a band in a negative RT control (HNF-3beta, FGF-10, FGF-1). CONCLUSIONS: The presence of TTF-1 in the neonatal TEF shows, for the first time, that parallels may be drawn between the experimental rat model of TEF and the human anomaly at the molecular level. Moreover, these results suggest that the fistula tract in the human neonate is derived from a respiratory cell lineage. This respiratory origin of the human TEF may explain the poor esophageal motility (and subsequent serious respiratory complications) of the distal segment after standard EA/TEF repair.

Humans↗

PubMed2002

Effective Nissen fundoplication length and bougie diameter size in young children undergoing laparoscopic Nissen fundoplication.

BACKGROUND/PURPOSE: Laparoscopic Nissen fundoplication (LNF) is utilized in the management of symptomatic gastroesophageal reflux disease (GERD) in children. An effective length of fundoplication and bougie size has never been established in infants and children requiring LNF for GERD. To determine this effective fundoplication length and appropriate bougie size, we analyzed all patients less than 15 kg undergoing LNF for GERD over a 2-year period. METHODS: Data recovered retrospectively included age, weight, gender, need for gastrostomy, length of postoperative hospitalization, operating time, bougie size, and fundoplication length. RESULTS: One hundred patients weighed less than 15 kg (mean, 7.23 kg). Mean operating time was 95 minutes (range, 31 minutes to 159 minutes). Gastrostomies were placed in 32 patients. Postoperative hospitalization averaged 1.8 days for elective LNF. Fundoplication length was measured in each patient and averaged 2.06 cm. Bougie size varied from 22F to 42F, and the size utilized was based on the patient's weight. There were no instances of dysphagia or the need for esophageal dilatation postoperatively. Two patients have been seen for recurrent symptoms. One patient has required a second LNF, and the other has a normal upper gastrointestinal study and pH study. CONCLUSION: This study of LNF in small children has shown that resolution of GERD symptoms in most patients can be accomplished with an average fundoplication length of approximately 2 cm and a graduated bougie size relative to the patient's weight.

Child, Preschool↗

PubMed2002

Laparoscopic adrenalectomy and esophagomyotomy.

Recent improvements in laparoscopic equipment, technique, and skills have contributed to advancement of the laparoscopic approach to even relatively rare pediatric surgical diseases. Two invasive operations that now may be approached laparoscopically are adrenalectomy and esophagomyotomy. Both techniques, initially described in the early 1990s, are particularly well suited for the laparoscopic approach and have become accepted as the preferred technique among general surgeons. Despite infrequent indications for either of these operations in children, pediatric surgeons experienced in minimally invasive techniques may apply the laparoscopic approach in a safe and effective manner. Furthermore, regarding achalasia in the pediatric population specifically, the offering of a less-invasive surgical approach may contribute toward more primary definitive surgical management being offered initially rather than after prolonged supportive medical care. The goal of this article is to familiarize the reader with the current laparoscopic approach to benign pediatric adrenal conditions and esophageal motility disorders in children.

Adenoma↗