Andrew D. Hershey

A fractionating column for analysis of nucleic acids

Abstract A readily prepared fractionating column is described that separates several ribonucleic and deoxyribonucleic acids from each other, including the closely similar nucleic acids of T2 and T4 bacteriophages. The column also distinguishes DNA that has been denatured by heat and DNA that has been broken by hydrodynamic shear from the starting material. Some notes are recorded also concerning the preparation of nucleic acids from bacteria and phage by the phenol method.

Sedimentation Rate as a Measure of Molecular Weight of DNA

Zone centrifugation of mixtures of two labeled DNAs at low concentrations in density gradients of sucrose permits accurate measurement of relative sedimentation rates. The individual rates are constant during the run. Measurements with DNAs from phages T2, T5, and lambda conform to the relation D(2)/D(1) = (M(2)/M(1))(0.35), where D and M refer to distances sedimented and molecular weights of the DNA pair. The results show that high molecular weight DNAs sediment artificially fast in the optical centrifuge, owing to a hitherto unknown effect of molecular interactions. The molecular weight of lambda DNA is 31 million, measured either from sedimentation rate or from tests of fragility under shear.

Depression and functional disability in chronic pediatric pain.

ObjectivesThe primary aim of this study was to describe pain characteristics, coping strategies, depression, and functional disability in children and adolescents with chronic pain and to examine potential factors that are associated with functional disability in a pediatric pain population. The secondary aim of this study was to compare functional disability in two chronic pain conditions: localized musculoskeletal pain and chronic daily headaches. SubjectsThe participants in this study were 73 pediatric pain patients with a variety of chronic pain conditions. Subjects in the second part of the study were a subset of patients (N = 44) from the pain clinic sample with chronic localized musculoskeletal pain and a subset of patients (N = 38) from the headache center of the same hospital who had chronic daily headaches. DesignPatients completed self-report measures of pain intensity, depression, coping strategies, coping efficacy, and functional disability. ResultsResults indicated that chronic pain had a substantial impact on the childrens lives and that depression was strongly associated with functional disability. Maladaptive coping was correlated with depression and disability; however, maladaptive coping was not independently associated with functional disability. A comparison between the two groups found significant differences in pain intensity and functional disability. The localized musculoskeletal pain group reported higher levels of disability and more difficulty coping than the chronic daily headache group. ConclusionsThe implications for treatment of chronic pain in children are discussed with an emphasis on greater attention to developmental issues and their relation to coping, emotional functioning, and disability in pediatric pain. Further research examining differences in coping and disability between different pediatric pain groups is also warranted.

PedMIDAS Development of a questionnaire to assess disability of migraines in children

BackgroundFor adults, disability produced by migraines has been assessed with a migraine-specific disability tool—MIDAS. The objective of this study was to develop and validate a similar tool that accurately depicts the disability of headaches in school-age children and adolescents. MethodsA six-question tool (PedMIDAS) was developed and administered to patients attending a tertiary referral center for pediatric headaches. Internal consistency and test/retest reliability were assessed. Validity was assessed by correlating scores with headache frequency, severity, and duration. Changes in the total score in response to treatment were assessed in a portion of the patients. ResultsThe PedMIDAS questionnaire was administered to 441 patients for a total of 724 trials. The mean score at the initial visit was 44.3 ± 47.9, whereas the overall mean score was 25.1 ± 36.5. A 2-week test/retest reliability assessment for 56 patients confirmed the stability of the instrument with a Pearson coefficient of 0.80. The correlation of the PedMIDAS score with frequency, severity, and duration had Pearson’s coefficient values of 0.58, 0.27, and 0.23. The PedMIDAS score was reduced to 20.0 ± 32.3 (p < 0.0001) at the first follow-up assessment with subsequent continued reduction. ConclusionsThe PedMIDAS questionnaire provided a developmentally sensitive, reliable, and valid assessment of the disability of childhood and adolescent headaches. This questionnaire provides a tool to assess the impact of migraines in children and to monitor response to treatment. Further research should focus on additional validation of the PedMIDAS using a larger population and sampling from other populations (e.g., primary care and community samples).

An upper limit to the protein content of the germinal substance of bacteriophage T2

Among the products of osmotic shock of bacteriophage T2 can be identified ghosts, nucleic acid, and a “nonsedimentable” protein amounting to about 3% of the total viral protein. The nonsedimentable protein is an authentic component of the phage and differs from ghost protein both antigenically and by failing to adsorb to bacteria. It is probably not combined with the viral nucleic acid and is not a basic protein, resembling, in fact, the ghost protein in amino acid composition. It is injected into the cell when the virus attaches to bacteria, but it is not an important precursor of the nonsedimentable protein in the viral offspring. Its function is unknown.

Effectiveness of Amitriptyline in the Prophylactic Management of Childhood Headaches

Objective.—To study the effectiveness of a standardized dose of amitriptyline, 1 mg/kg, for childhood headaches.

Migraine Headaches and Sleep Disturbances in Children

Objective.—The aim of the present study was to investigate the prevalence of sleep disturbances in children with migraine headaches and to describe individual differences in sleep behaviors based on headache features (eg, frequency, duration, intensity).

Quality of life in paediatric migraine: characterization of age‐related effects using PedsQL 4.0

The aim of this study was to measure quality of life (QOL) across a broad age range of paediatric migraine patients. Children and adolescents (n = 686) with migraine completed the Pediatric Quality of Life Inventory, version 4.0 (PedsQL 4.0) and a standardized headache assessment at an initial clinic visit. The sample size for each PedsQL age group was: age 2-4 = 21, age 5-7 = 86, age 8-12 = 298, and age 13-18 = 281. Mean total score was 72.7 ± 14.8, significantly less than healthy norms (P < 0.01). Teens reported lower School Functioning than older and young children (P < 0.05) and young children reported lower Social Functioning than older children and teens (P < 0.001). A moderate relation was found between self and parent report. Age-related effects on QOL have implications for the evaluation and management of migraine in paediatric practice. The self and parent report forms of the PedsQL can be used in a practice setting.

Coenzyme Q10 deficiency and response to supplementation in pediatric and adolescent migraine.

Background.—Coenzyme Q10 (CoQ10) has been suggested to be effective in the prevention of migraine, and levels can be quantified with standardized reference ranges.

Use of the ICHD-II criteria in the diagnosis of pediatric migraine

Objective.—To evaluate the sensitivity of the new International Classification of Headache Disorders‐2nd edition (ICHD‐II) criteria in the diagnosis of childhood migraine and to propose specific criteria for the diagnosis of childhood migraine.