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Michael A Miller

Publications and source records attributed to Michael A Miller.

At least 19 recordsLinked to original sources
PubMed2026

Ultrasound-Actuated Gene Editing in Human Kidney Organoids.

Efficient delivery of gene editing ribonucleoproteins (RNPs) into the interior of solid tissues remains a key hurdle to the clinical translation of non-viral CRISPR-Cas9 technologies. Here, we report acoustically-actuated peptide nanoemulsions (NPeps) that can be spatiotemporally guided and activated by ultrasound to ballistically deliver RNPs into cells within the bulk of dense 3D cellular structures. Using human kidney organoids as a model, we demonstrate NPep vectors improve the spatial profile of gene editing in the organoid mass relative to commercial lipofection reagents, without disruption of tissue structure or qualitative viability features. This technologic paradigm is poised to advance imaging-guided, deep tissue RNP delivery modalities to expand the clinical diagnostic and therapeutic potential of CRISPR-Cas9 editing strategies.

Humans↗
PubMed2007

Treatment of skeletally mature ovariectomized rhesus monkeys with PTH(1-84) for 16 months increases bone formation and density and improves trabecular architecture and biomechanical properties at the lumbar spine.

UNLABELLED: Histomorphometric studies of treatments for osteoporosis in humans are restricted to iliac crest biopsies. We studied the effects of PTH(1-84) treatment at the lumbar spine of skeletally mature ovariectomized rhesus monkeys. PTH increased bone turnover, rapidly normalized BMD, and increased vertebral compressive strength. PTH increased trabecular bone volume primarily by increasing trabecular number by markedly increasing intratrabecular tunneling. INTRODUCTION: Histomorphometric studies of the anabolic properties of PTH(1-84) (PTH) and related peptides in human bone are restricted to iliac crest biopsies. The ovariectomized (OVX) monkey is an accepted model of human postmenopausal bone loss and was used to study the effects of PTH treatment at clinically relevant skeletal sites. MATERIALS AND METHODS: Skeletally mature rhesus monkeys were OVX or sham-operated and, after a bone depletion period of 9 months, treated daily for 16 months with PTH (5, 10, or 25 microg/kg). Markers of bone formation (serum osteocalcin) and resorption (urine N-telopeptide [NTX]) and lumbar spine BMD were measured throughout the study. Trabecular architecture and vertebral biomechanical properties were quantified at 16 months. RESULTS: PTH treatment induced dose-dependent increases in bone turnover but did not increase serum calcium. Osteocalcin was significantly increased above OVX controls by 1 month. NTX was significantly elevated at 1 month with the highest dose, but not until 12 months with the 5 and 10 microg/kg doses. Lumbar spine BMD was 5% lower in OVX than in sham animals when treatment was started. All PTH doses increased BMD rapidly, with sham levels restored by 3-7 months with 10 and 25 microg/kg and by 16 months with 5 microg/kg. PTH treatment increased trabecular bone volume (BV/TV), primarily by increasing trabecular number, and dose-dependently increased bone formation rate (BFR) solely by increasing mineralizing surface. The largest effects on BV/TV and yield load occurred with the 10 microg/kg dose. The highest dose reduced trabecular thickness by markedly increasing intratrabecular tunneling. CONCLUSIONS: PTH treatment of OVX rhesus monkeys increased bone turnover and increased BV/TV, BMD, and strength at the lumbar spine. All PTH doses were safe, but the 10 microg/kg dose was generally optimal, possibly because the highest dose resulted in too marked a stimulation of bone remodeling.

Animals↗
PubMed2006

Evaluation of [11C]hemicholinium-15 and [18F]hemicholinium-15 as new potential PET tracers for the high-affinity choline uptake system in the heart.

[(11)C]Hemicholinium-15 ([(11)C]HC-15) and [(18)F]hemicholinium-15 ([(18)F]HC-15) have been synthesized as new potential PET tracers for the heart high-affinity choline uptake (HACU) system. [(11)C]HC-15 was prepared by N-[(11)C]methylation of the appropriate precursor, 4-methyl-2-phenyl-morpholin-2-ol, using [(11)C]CH(3)OTf in 55-70% radiochemical yield decay corrected to end of bombardment (EOB) and 2-3Ci/mumol specific activity at end of synthesis (EOS). [(18)F]HC-15 was prepared by N-[(18)F]fluoromethylation of the precursor using [(18)F]FCH(2)OTf in 20-30% radiochemical yield decay corrected to EOB and >1.0Ci/mumol specific activity at EOS. The biodistribution of both compounds was determined in rats at 20min post-intravenous injection, and the results show the heart region uptakes 1.32+/-0.75%ID/g in R-ventricle for [(11)C]HC-15 and 1.28+/-0.81%ID/g in L-ventricle for [(18)F]HC-15, respectively. The dynamic PET imaging studies of [(11)C]HC-15 in rats were acquired 60min post-intravenous injection of the tracer using the IndyPET-II scanner. For the blocking experiments, the rats were intravenously pretreated with 3.0mg/kg of unlabeled HC-15 prior to [(11)C]HC-15 injection. [(11)C]HC-15 rat heart PET studies show rapid heart uptake to give clear heart images. The rat heart PET blocking studies found no significant blocking effect. The dynamic PET studies in normal and ablated dogs were performed using Siemens PET scanner with [(13)N]NH(3), [(11)C]HC-15, and [(18)F]HC-15. PET studies in dogs of both [(11)C]HC-15 and [(18)F]HC-15 also show significant heart uptake and give images of the heart. However, there is no significant change in [(11)C]HC-15 L-ventricle uptake following radiofrequency ablation in the dog. These results suggest that the localization of HC-15 tracers in the heart is mediated by non-specific processes, and the visualization of HC-15 tracers on the heart is related to non-specific binding of HACU.

Animals↗
PubMed2006

Restoring chemotherapy and hormone therapy sensitivity by parthenolide in a xenograft hormone refractory prostate cancer model.

BACKGROUND: Nuclear Factor kappa B (NFkappaB) is a eukaryotic transcription factor that is constitutively active in human cancers and can be inhibited by the naturally occurring sesquiterpene lactone, parthenolide (P). METHODS: The in vitro effects of P were assessed using the androgen independent cell line, CWR22Rv1, and human umbilical endothelial cells (HUVECs). The in vivo activity of P as a single agent and its ability to augment the efficacy of docetaxel and the anti-androgen, bicalutamide, were determined using the CWR22Rv1 xenograft model. RESULTS: Parthenolide at low micromolar concentration inhibited proliferation of CWR22Rv1 and HUVEC cells, promoted apoptosis and abrogated NFkappaB-DNA binding. Parthenolide downregulated anti-apoptotic genes under NFkappaB control, TRAF 1 and 2, and promoted sustained activation of c-jun-NH2 kinase (JNK). Parthenolide also augmented the in vivo efficacy of docetaxel and restored sensitivity to anti-androgen therapy. CONCLUSION: These studies demonstrate parthenolide's anti-tumor and anti-angiogenic activity, and its potential to augment the efficacy of chemotherapy and hormonal therapy.

Androgen Antagonists↗
PubMed2006

Oocyte signals derived from polyunsaturated fatty acids control sperm recruitment in vivo.

A fundamental question in animal development is how motile cells find their correct target destinations. During mating in the nematode Caenorhabditis elegans, males inject sperm through the hermaphrodite vulva into the uterus. Amoeboid sperm crawl around fertilized eggs to the spermatheca--a convoluted tube where fertilization occurs. Here, we show that polyunsaturated fatty acids (PUFAs), the precursors of eicosanoid signalling molecules, function in oocytes to control directional sperm motility within the uterus. PUFAs are transported from the intestine, the site of fat metabolism, to the oocytes yolk, which is a lipoprotein complex. Loss of the RME-2 low-density lipoprotein (LDL) receptor, which mediates yolk endocytosis and fatty acid transport into oocytes, causes severe defects in sperm targeting. We used an RNAi screen to identify lipid regulators required for directional sperm motility. Our results support the hypothesis that PUFAs function in oocytes as precursors of signals that control sperm recruitment to the spermatheca. A common property of PUFAs in mammals and C. elegans is that these fats control local recruitment of motile cells to their target tissues.

Animals↗
PubMed2006

The role of gap junctions in Caenorhabditis elegans oocyte maturation and fertilization.

We have investigated the role of gap junctions in Caenorhabditis elegans oocyte maturation and fertilization. Gap junctions are observed between oocytes and the surrounding ovarian sheath cells in wild-type gonads. The sheath transcription factor CEH-18 is required to negatively regulate oocyte maturation, mitogen-activated protein kinase (MAPK) activation, and ovulation. Transmission electron microscopy (TEM) indicates that sheath/oocyte gap junctions are rare or absent in ceh-18(mg57) null mutant gonads. To test the hypothesis that gap junctions negatively regulate oocyte maturation, we performed an RNAi screen of innexin genes, which encode channel-forming proteins. Here we show that INX-14 and INX-22 are required in the female germ line to inhibit oocyte maturation, MAPK activation, and ovulation. Genetic analysis and TEM are consistent with INX-14 and INX-22 being components of sheath/oocyte gap junctions. Our results support the hypothesis that gap junctions maintain oocytes in meiotic prophase I when sperm are absent. We also implicate these channels in regulating sheath cell contractile activity and sperm recruitment to the spermatheca, the site of sperm storage and fertilization. Together with previous studies, our results help establish the C. elegans gonad as a model system for investigating the molecular mechanism(s) by which gap junctions regulate meiosis and fertilization.

Animals↗
PubMed2006

Is digital intubation an option for emergency physicians in definitive airway management?

OBJECTIVES: This study was designed to determine whether digital intubation is a valid option for definitive airway control by emergency physicians. METHODS: Digital intubation was performed by 18 emergency medicine residents and 4 staff emergency medicine physicians on 6 different cadavers. Placement was confirmed by direct laryngoscopy. The total time for all attempts used, as well as the number of attempts, was recorded. Each participant attempted intubation on all 6 cadavers. RESULTS: For 5 of the 6 cadavers, successful intubation occurred 90.9% of the time (confidence interval [CI], 85.5%-96.3%) for all participants. The average number of attempts for these 5 cadavers was 1.5 (CI, 1.4-1.7), and the average time required for success or failure was 20.8 seconds (CI, 16.9-24.8). The sixth cadaver developed soft tissue damage and a false passage near the vocal cords resulting in multiple failed attempts. CONCLUSIONS: Although the gold standard for routine endotracheal intubation remains to be direct laryngoscopy, its effectiveness in certain situations may be limited. We believe that digital intubation provides emergency physicians with another option in securing the unprotected airway.

Aged↗
PubMed2006

Does the clinical use of ethanol-based hand sanitizer elevate blood alcohol levels? A prospective study.

BACKGROUND: Ethanol-based hand sanitizers (EBHSs) are used in most health care facilities in the United States. Infection control personnel advocate the use of generous quantities of EBHS before and after contact with patients. Although it is assumed that little systemic absorption of ethanol occurs during EBHS use, many alcohols are absorbed to varying degrees via the transdermal route. Ethanol intoxication by employees in the medical workplace is a potentially serious finding, and it is of forensic and medical-legal importance to elucidate the effects of frequent use of EBHS upon serum blood ethanol levels (BELs). To investigate the effect of frequent use of EBHS upon serum blood ethanol concentrations, we prospectively studied 5 volunteers undergoing frequent application of EBHS. METHODS: Enrolled subjects applied 5 mL of the product (62% denatured ethyl alcohol manufactured by Kimberley-Clark, Roswell, GA) to both hands and rubbed until dry. This activity was repeated 50 times over 4 hours. Participants had their blood drawn before as well as after completing the study. Each participant was without alcohol exposure during the 12 hours preceding the study. RESULTS: Five volunteers were enrolled. All had an initial blood ethanol level of less than 5 mg/dL. All 5 participants completed the 4-hour study. There were no noted adverse reactions during the study. Blood ethanol level upon completion of the 50 applications of EBHS was less than 5 mg/dL in all 5 study participants. CONCLUSION: The results of this study demonstrate that use of ethanol-based hand sanitizers, when frequently used in accordance with labeling, do not raise serum blood ethanol levels.

Administration, Cutaneous↗
PubMed2006

Clinical course and toxicokinetic data following isolated citalopram overdose in an infant.

OBJECTIVE: Despite the frequency of use of citalopram, its clinical effects and pharmacokinetics in overdose in the pediatric patient are not well described. We describe the clinical course and drug levels following the ingestion of citalopram by a 10-month-old female. CASE REPORT: A 10 month-old female ingested an unknown amount of citalopram. Approximately 40 min after ingestion, the child developed horizontal nystagmus, followed by a generalized, tonic-clonic seizure that lasted 2 to 3 min very shortly thereafter. The child received 1 mg of midazolam intramuscularly (IM), followed by 1 mg of midazolam intravenously (IV) for termination of this seizure, and was given a loading dose of 20 mg/kg of fosphenytoin IV. Elective orotracheal intubation was done to protect the airway. Despite the use of midazolam and fosphenytoin, the child had another seizure approximately 85 min following the ingestion. A third seizure was noted at approximately 100 min post-ingestion. In the course of treatment, activated charcoal was administered via nasogastric tube, and IV midazolam and phenobarbital were given. The child was transferred to a nearby facility with pediatric intensive care capabilities in stable condition. The child did not experience any hypotension or dysrhythmia, and the electrocardiographic QTc and QRS complex were normal throughout the clinical course. During the subsequent 48 h, the child awoke and regained normal function. This child's recovery was uneventful, and the child was discharged home without sequelae. Plasma levels of citalopram were 1400 ng/ml, 583 ng/ml, 416 ng/ml, and 296 ng/ml, at one, six, 13, and 23 h post-ingestion, respectively. The first level likely represents a predistributional level with subsequent levels giving an elimination t1/2 of 17.38 h. CONCLUSION: We report a case of citalopram poisoning in a 10-month-old infant with refractory seizures, and an absence of cardiovascular events with subsequent excellent outcome. The elimination of the parent drug corresponds to an approximate t1/2 of 15-20 h in this single case.

Charcoal↗
PubMed2006

Sperm and oocyte isolation methods for biochemical and proteomic analysis.

Caenorhabditis elegans gonad is a simple model to investigate molecular mechanisms that regulate fundamental cell and developmental processes. The strength of the model is that C. elegans is amenable to genetic manipulation. The complete genome sequence, advances in mass spectrometry, and RNA-mediated interference (RNAi) are now providing a technical infrastructure that complements biochemical and proteomic approaches. This chapter describes simple methods for sperm and oocyte isolation and gonad liberation that can be performed routinely in the lab, without expensive equipment. These methods are ideal for biochemical and proteomic applications, including those aiming to identify proteins based on affinity or biological activity. Germline mRNA expression profiles, RNAi feeding clones, and Gateway-engineered ORFeome vectors are available to help validate experimental results.

Animals↗