Biomedical subjects

J Hendrickson

Publications and source records attributed to J Hendrickson.

17 recordsLinked to original sources

PubMed2004

Vacuum Rabi splitting with a single quantum dot in a photonic crystal nanocavity.

Cavity quantum electrodynamics (QED) systems allow the study of a variety of fundamental quantum-optics phenomena, such as entanglement, quantum decoherence and the quantum-classical boundary. Such systems also provide test beds for quantum information science. Nearly all strongly coupled cavity QED experiments have used a single atom in a high-quality-factor (high-Q) cavity. Here we report the experimental realization of a strongly coupled system in the solid state: a single quantum dot embedded in the spacer of a nanocavity, showing vacuum-field Rabi splitting exceeding the decoherence linewidths of both the nanocavity and the quantum dot. This requires a small-volume cavity and an atomic-like two-level system. The photonic crystal slab nanocavity--which traps photons when a defect is introduced inside the two-dimensional photonic bandgap by leaving out one or more holes--has both high Q and small modal volume V, as required for strong light-matter interactions. The quantum dot has two discrete energy levels with a transition dipole moment much larger than that of an atom, and it is fixed in the nanocavity during growth.

Journal Article↗

PubMed2001

Juvenile arthritis and autoimmunity to type II collagen.

OBJECTIVE: Joint inflammation in juvenile rheumatoid arthritis (JRA) is sometimes associated with an autoimmune response to type II collagen (CII), a cartilage-specific protein. To test the hypothesis that down-regulation of autoimmunity to CII can be accomplished in JRA by oral administration of CII, an open-label study of CII was performed in 9 patients with JRA. METHODS: Seven rheumatoid factor-negative JRA patients with polyarticular disease and 2 JRA patients with pauciarticular disease (1 with early onset and 1 with late onset) were treated for 3 months with oral bovine CII. Patients were examined for disease activity and underwent routine laboratory testing at monthly intervals. Two of the patients had flares of disease when treatment was discontinued, and these patients were re-treated for an additional 3 months. To test the hypothesis that oral tolerance induces an immune deviation of T cells, peripheral blood mononuclear cells from patients were collected before and after treatment and cultured with CII. Supernatants and RNA were collected and analyzed for the presence of various cytokines. RESULTS: Eight patient trials met the criteria for clinical improvement outlined by Giannini and coworkers in 1997. None of the patients had any side effects from the treatment. In 6 of the 8 patients who improved, interferon-gamma production decreased after oral CII therapy, correlating with clinical improvement, while 6 patients had increases in levels of transforming growth factor beta3. CONCLUSION: These results are encouraging. The possible beneficial effect of oral CII in JRA merits further investigation.

Administration, Oral↗

PubMed2001

CORD9 a new locus for arCRD: mapping to 8p11, estimation of frequency, evaluation of a candidate gene.

PURPOSE: To determine the locus of the mutant gene causing autosomal recessive cone-rod dystrophy (arCRD) in a consanguineous pedigree, to evaluate a candidate gene expressed in retina that maps to this locus, and to estimate the percentage of arCRD cases caused by mutations in this gene. METHODS: DNAs from family members were genotyped for markers covering the entire genome at an average spacing of approximately 9 centimorgans (cM). The data were input into a pedigree computer program to produce output files used to calculate lod scores. Significant linkage was revealed at 8cen, prompting the genotyping of a number of additional markers. Exons of a candidate gene were sequenced directly by standard fluorescent dideoxy methods. Haplotype analysis was performed with markers in this locus in 13 multiplex and 2 simplex CRD families in which neither parent had disease. RESULTS: Four-point linkage analysis gave a maximum lod score of approximately 7.6 at both D8S1769 and GATA101H09 in the large consanguineous family. Recombination events defined an interval of 8.7 cM between D8S1820 and D8S532 within which the gene must lie. This 8p11 locus (CORD9) is immediately distal to but distinct from the RP1 autosomal dominant RP (adRP) locus. Two islands of homozygosity were found in this locus: The alleles of 6 of 10 markers in one of the islands and 2 of 4 in the other were homozygous. The UniGene cluster Hs.8719 (UniGene System, provided by the National Center for Biotechnology Information and available at http://www.ncbi.nlm.nih.gov/UniGene), which tags a gene with significant homology to Dual Specificity Phosphatase 3, maps within the CORD9 interval and is highly expressed in the retina. To evaluate this gene as a potential disease candidate, intron-exon structure was determined, and exons were screened in the consanguineous family. No variants were found that could be related to disease. Haplotype analysis of 15 other families with CRD, using markers at CORD9, excluded this locus in 9 of 15. CONCLUSIONS: A new arCRD locus (CORD9) has been identified corresponding to a yet unidentified gene in the 8.7-cM interval D8S1820-D8S532. No mutations were found in one candidate gene in affected members of the primary study family. Haplotype analysis of a cohort of 13 multiplex and 2 simplex families with CRD ruled out the CORD9 gene in 9 of 15 of the families. To date, a total of 126 loci carrying gene mutations causing various forms of retinal degeneration have been mapped, and the mutant gene has been identified in 64 of them. However, only 2 loci for arCRD have been documented. This is the report of a third.

Chromosome Mapping↗

PubMed1998

The risk of teen mothers having low birth weight babies: implications of recent medical research for school health personnel.

This article reviews recent medical research on the relationship between young maternal age and the incidence of low birth weight infants. One line of research, "nature," emphasizes biological factors in early adolescence such as immaturity of the female reproductive system and inadequate prenatal weight gain. "Nurture," another research focus, stresses sociocultural attributes of teen mothers such as poverty and minority status. Young maternal age alone does not explain the higher rates of low birth weight infants born to adolescent females. Both biological and sociocultural factors, plus lifestyle choices made by adolescents, combine to raise or lower the risk of delivering a low birth weight infant. School health personnel need to link their health promotion efforts to those of other community organizations serving adolescents and their families.

Adolescent↗

PubMed1996

Lilliputian hallucinations in schizophrenia: case report and review of literature.

A patient with chronic schizophrenia who had visual hallucinations of lilliputian nature is described. The authors review the studies on prevalence of visual hallucinations in schizophrenic patients and suggest that visual hallucinations may be more common in schizophrenia than previously acknowledged. The authors suggest a routine enquiry about visual hallucination in clinical practice and emphasize the need for further research under controlled conditions.

Adult↗

PubMed1995

Angelman syndrome.

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Angelman Syndrome↗

PubMed1992

Angelman syndrome: clinical profile.

To further delineate the clinical and developmental features of Angelman syndrome, we collected data through three sources of information: (1) physical examinations; (2) laboratory data and family questionnaire data of affected individuals; and (3) literature review. The questionnaire data describes a generally normal prenatal and birth history. Feeding difficulties, developmental delay, or seizures were the presenting problems in all infants. The diagnosis of Angelman syndrome, however, was not made in any infant prior to 1 year of age. Except for seizures, no medical or surgical complication was common, although a variety of visual complaints or findings were common. Sixty percent of Angelman syndrome children had a cytogenetically demonstrated deletion of chromosome 15q11-q13. The individuals with and without a deletion could not be differentiated clinically. Diagnosis in early childhood is therefore difficult, and a high index of suspicion is recommended.

Adolescent↗

PubMed1985

Mexiletine: double-blind comparison with procainamide in PVC suppression and open-label sequential comparison with amiodarone in life-threatening ventricular arrhythmias.

The antiarrhythmic effects of mexiletine (n = 14) were compared to procainamide (n = 16) by a double-blind parallel protocol in 30 patients (group I) with frequent premature ventricular contractions (PVCs) (greater than 20/hr), and to amiodarone by an open-label sequential approach in 25 patients (mean left ventricular ejection fraction of 32.6 +/- 13.4%) with life-threatening ventricular arrhythmias (group II) resistant to two or more conventional agents. The predetermined end point of therapy in group I patients was met in 6 of 14 (43%) given mexiletine, with 7 (50%) requiring drug discontinuation for severe gastrointestinal or central nervous system side effects and only 3 of 16 patients (19%) given procainamide, with 5 (31%) developing limiting side effects. Increases in dose led to a higher efficacy rate for PVC suppression with a corresponding increase in side effects with mexiletine; with procainamide, the higher dose was not associated with greater PVC suppression. In group II patients, mexiletine was effective in 4 (16%), with one patient discontinuing the drug during long-term therapy; mexiletine was ineffective in 16 (64%) and early side effects developed in 5 (20%). Patients not responding to or not tolerating mexiletine were given amiodarone; 20 of 21 (95%) responded with arrhythmia control after the loading dose. During a mean follow-up period of 2 years, sudden death occurred in two patients, death from heart failure in two, and death from subarachnoid hemorrhage in one patient; 15 (75%) patients are alive and free of arrhythmia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1985

Electrophysiologic and antiarrhythmic effects of sotalol in patients with life-threatening ventricular tachyarrhythmias.

Sotalol is a unique beta-blocker that lengthens cardiac repolarization and effective refractory period (ERP). Its efficacy after intravenous (1.5 mg/kg) and oral (160 to 480 mg bid) administration was therefore evaluated in 37 patients with refractory recurrent ventricular tachycardia/fibrillation (VT/VF). Thirty-five patients, 33 with inducible VT/VF, underwent electrophysiologic testing. Intravenous sotalol lengthened the ERP in the atrium (+24.6%, p less than .01), atrioventricular node (+24.9%, p less than .01), and ventricle (+14.9%, p less than .01). It also significantly lengthened sinus node recovery time, corrected QT interval (QTc), and the AH interval, but not the HV interval. Sotalol prevented reinduction of VT/VF in 15 patients (45.5%). Twenty-five of the 33 patients (15 with positive results of electrophysiologic tests; 10 with negative results) were given oral sotalol. The drug was ineffective in seven (26.9%) and aggravated arrhythmia in one (3.8%). In four patients sotalol was withdrawn because of side effects; arrhythmias recurred late in two (7.7%). Eleven patients (42.3%) have continued on oral sotalol over a mean follow-up period of 9.2 +/- 8.6 months. Sotalol reduced (n = 21) total premature ventricular complex (PVC) count on the Holter electrocardiogram by 73% (p less than .01), paired PVCs by 89% (p less than .01), and beats of ventricular tachycardia by 95% (p less than .01). In 52% (n = 11), total reduction in PVCs was at least 85%, and incidence of paired and tachycardiac beats was reduced at least 90% (group A). In the remainder (n = 10), PVC suppression was not significant (group B). Group A included nine patients with nonreinducible VT/VF and two in whom it was reinducible; in group B, eight of 10 patients had reinducible VT/VF. The difference between the two groups (Fisher exact test) was significant (p less than .01). The prevention of reinduction of VT/VF by intravenous sotalol and suppression of spontaneously occurring arrhythmias by the oral drug were both predictive of long-term drug efficacy. Sotalol is a significant advance in the short- and long-term management of life-threatening ventricular tachyarrhythmias.

Adult↗

PubMed1984

Amiodarone-digoxin interaction: clinical significance, time course of development, potential pharmacokinetic mechanisms and therapeutic implications.

Administration of amiodarone (600 to 1,600 mg/day) to 28 patients during long-term digoxin therapy (0.25 +/- 0.05 mg/day) increased serum digoxin level from 0.97 +/- 0.45 to 1.98 +/- 0.84 ng/ml (p less than 0.001). Gastrointestinal side effects occurred in nine patients, central nervous system reactions occurred in five and cardiovascular reactions occurred in four. Pharmacokinetic studies in six patients with a 1 mg intravenous digoxin dose before and during amiodarone therapy increased serum digoxin level at 30 minutes from 8.59 +/- 1.68 to 10.07 +/- 1.70 ng/ml (p less than 0.05). Amiodarone caused a 31% prolongation of digoxin elimination half-life from 49.5 +/- 8.8 to 65.0 +/- 28.8 hours, but the increase in half-life was not statistically significant. Total body clearance was reduced significantly (29%, p less than 0.05) from 2.05 +/- 0.76 to 1.46 +/- 0.64 ml/min per kg. Nonrenal clearance also showed a significant decrease (33%, p less than 0.05) from 1.20 +/- 0.46 to 0.80 +/- 0.30 ml/min per kg. The renal clearance decreased by 22% and the volume of distribution decreased by 11% after amiodarone therapy, but these changes were not significant. The data show that the mechanism of digoxin-amiodarone interaction is multifactorial and emphasize the need for close monitoring of serum digoxin levels and clinical features during concurrent digoxin-amiodarone therapy.

Adult↗

PubMed1983

Amiodarone in refractory life-threatening ventricular arrhythmias.

Ninety-six patients with life-threatening ventricular arrhythmias refractory to two or more conventional agents were treated with amiodarone and followed for 6 to 40 months (mean, 15 months). Currently, 75 are alive and well. Seven patients died from nonarrhythmic and five from arrhythmic causes. Nonfatal arrhythmias recurred in four patients, one with early and three with late onset. Intolerable side effects occurred in five patients but heart failure was not aggravated by the drug. On 24-hour Holter recordings done before and serially during therapy in 72 patients, amiodarone eliminated episodes of ventricular tachycardia and complex ectopy and reduced total ectopic beat counts by 90% or more in all but 4 patients. In contrast, ventricular tachycardia inducible by programmed electrical stimulation was suppressed in only 50% of patients, but failure of such suppression did not compromise an excellent clinical outcome. Thus, amiodarone is highly effective in the prophylaxis of recurrent refractory life-threatening ventricular arrhythmias.

Acute Disease↗

PubMed1983