Characterization of chronic daily headaches in children in a multidisciplinary headache center

BACKGROUND

Chronic daily headaches (CDH) occur in >4% of the adult population. The criteria for CDH, however, are controversial. In children, the characterization of frequent headaches and CDH is limited.

METHODS

A Headache Center to characterize headaches in children (3 to 18 years old) was established. Over 34 months, 577 children have been evaluated. With use of a definition of > or =15 headaches per month, 200 (34.6%) children had CDH.

RESULTS

The average age at the first headache in these children was 9.3 +/- 3.6 years, whereas the average age at presentation to the Headache Center was 12.5 +/- 3.1 years. Sixty-eight percent were girls, 88% were Caucasian, and 11% were African American. Ninety-two percent clinically had migraine headaches, whereas 60.5% met the International Headache Society migraine criteria. The pain was pulsatile in 79%, 63.5% had nausea with or without vomiting, and 59.5% had photophobia and phonophobia. Three subcategories emerged, with 37% having frequent headaches but not daily, 43.5% having episodic daily headaches, and 19.5% having a continuous headache.

CONCLUSION

The features of CDH in children most closely match those of migraine. A clear division of these children using frequency identifies three groups: frequent headaches (15 to 29), daily intermittent, and daily continuous. The daily continuous group is the most unique; however, the nature of these headaches continues to remain migrainous.

Tolerability and effectiveness of prochlorperazine for intractable migraine in children

OBJECTIVE

To study the effectiveness of prochlorperazine in aborting severe, intractable migraines in children.

STUDY DESIGN

Patients for this study were drawn from the population seen and evaluated in the Headache Center at Cincinnati Children's Hospital Medical Center. All patients were diagnosed with migraine headache by both clinical and International Headache Society criteria. The effectiveness of intravenous prochlorperazine in 20 consecutive patients referred to the emergency department for severe, prolonged migraines was retrospectively reviewed.

RESULTS

Patients evaluated in this study presented with a mean headache severity of 8.4 on a 0- to 10-point scale and an average duration of 54 hours. At 1 hour, 90% of the patients reported feeling better with 50% becoming pain-free. A 50% or greater reduction in severity occurred in 75% of patients at 1 hour and in 95% at 3 hours. At 3 hours, 95% of the patients reported feeling better, and 60% were pain-free. Only 1 patient failed to respond to prochlorperazine.

CONCLUSION

Prochlorperzaine was shown to be highly effective in aborting intractable migraines in children. It was well tolerated with no significant side effects. Additional large, double-blinded, randomized, placebo-controlled studies are needed to further investigate its effectiveness.

HPLC analysis of reduced and oxidized coenzyme Q(10) in human plasma

BACKGROUND

The percentage of reduced coenzyme Q(10) (CoQ(10)H(2)) in total coenzyme Q(10) (TQ(10)) is decreased in plasma of patients with prematurity, hyperlipidemia, and liver disease. CoQ(10)H(2) is, however, easily oxidized and difficult to measure, and therefore reliable quantification of plasma CoQ(10)H(2) is of clinical importance.

METHODS

Venous blood was collected into evacuated tubes containing heparin, which were immediately placed on ice and promptly centrifuged at 4 degrees C. The plasma was harvested and stored in screw-top polypropylene tubes at -80 degrees C until analysis. After extraction with 1-propanol and centrifugation, the supernatant was injected directly into an HPLC system with coulometric detection.

RESULTS

The in-line reduction procedure permitted transformation of CoQ(10) into CoQ(10)H(2) and avoided artifactual oxidation of CoQ(10)H(2). The electrochemical reduction yielded 99% CoQ(10)H(2). Only 100 microL of plasma was required to simultaneously measure CoQ(10)H(2) and CoQ(10) over an analytical range of 10 microg/L to 4 mg/L. Intra- and interassay CVs for CoQ(10) in human plasma were 1.2-4.9% across this range. Analytical recoveries were 95.8-101.0%. The percentage of CoQ(10)H(2) in TQ(10) was approximately 96% in apparently healthy individuals. The method allowed analysis of up to 40 samples within an 8-h period.

CONCLUSIONS

This optimized method for CoQ(10)H(2) analysis provides rapid and precise results with the potential for high throughput. This method is specific and sufficiently sensitive for use in both clinical and research laboratories.

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.

BACKGROUND

Amitriptyline has been shown to be effective for the prophylaxis of migraine in adults. Studies in children, however, have been quite limited. In adults, the suggested effective dose range is 10 to 150 mg. In children, a standardized dosage is often not used, resulting in a dosage range in clinical practice that often varies from a very low dose to a dose equivalent to that used in adults.

METHODS

Children with more than three headaches per month were treated with amitriptyline, slowly increasing the dose to 1 mg/kg per day. The frequency, severity, and duration of their headaches were initially evaluated and subsequently measured at each follow-up evaluation. Two hundred seventy-nine children had headaches occurring frequently enough to indicate prophylactic treatment. Of these children, 192 (68.8%) were treated with amitriptyline. The average age at presentation was 12.0 (+/- 3.0) years. The ratio of boys to girls was 1:1.74. The average frequency of headaches was 17.1 (+/- 10.1) days per month. The average severity was 6.84 (+/- 1.67) on a 10-point pain scale. The average duration was 11.5 (+/- 15.0) hours. The most frequent diagnoses using International Headache Society criteria were migraine (60.6%), migraine with aura (7.9%), and tension-type headache (10.4%). Of these children, 146 have been seen for at least one follow-up examination, occurring on average 67.3 (+/- 32.3) days after beginning prophylactic treatment.

RESULTS

A total of 84.2% of the children reported an overall perception of being better, while 11.6% reported being the same. The frequency of headaches improved to 9.2 (+/- 10.0) days per month. The average severity was reduced to 5.1 (+/- 2.1), and the average duration was reduced to 6.3 (+/- 11.1) hours. If daily or continuous headaches were excluded, the improvements were more marked. Minimal side effects were reported from these children and their families. Long-term evaluation (156 to 415 days) showed continued sustained improvement.

CONCLUSIONS

Amitriptyline is an effective prophylactic medication for children with frequent headaches. A standardized dosing regimen results in a significant number of children responding with minimal side effects. The children are able to tolerate this dosing scheme and demonstrate good adherence to a dosing schedule of once a day.

Diagnosis of migraine in children attending a pediatric headache clinic

The International Headache Society (IHS) criteria for migraine are not sufficient to diagnose migraine in children. Specifically, the duration and localization of the headache are different in children and adults with migraine. This study compared the formal IHS criteria with pediatric-amended IHS criteria and IHS criteria with the duration factor removed in children younger than 18 years. In addition, the older criteria by Vahlquist and by Prensky and Sommer were also compared. Finally, clinical diagnosis of migraine was compared with IHS criteria with the duration factor removed. The study showed that many children with a shorter duration headache have migraine and also that a number of children with a very long duration of headaches still fit the diagnosis of migraine. Unilateral headache is quite uncommon. The majority of children with migraine complained of bilateral headaches. It is concluded that the IHS criteria for pediatric migraine should be revised. We suggest making the duration factor a minor criteria for migraine in children or to exclude headaches lasting longer than 72 hours only in children younger than 15 years.

Characterization of the substance P (NK-1) receptor in tunicamycin-treated transfected cells using a photoaffinity analogue of substance P

Chinese hamster ovary cells expressing the N-glycosylated substance P (NK-1) receptor were treated with the glycosylation inhibitor tunicamycin and photolabeled with 125I-Bolton-Hunter-p-benzoyl-L-phenylalanine8-substance P. Two radioactive proteins of M(r) 80,000 and 46,000, representing the glycosylated and nonglycosylated substance P (NK-1) receptor, respectively, were observed. The IC50 for the inhibition of photolabeling of both receptor forms was 0.3 +/- 0.1 nM for substance P and 30 +/- 5 nM for neurokinin A (substance K). Thus, glycosylation of the substance P (NK-1) receptor has no detectable effect on the affinity of the substance P (NK-1) receptor for substance P or neurokinin A (substance K).

Crystallization and preliminary crystallographic studies of Saccharomyces cerevisiae alcohol dehydrogenase I

The cytoplasmic yeast alcohol dehydrogenase I crystallized at 5 degrees C as hexagonal plates or short columns in the presence of NAD+ and 2,2,2-trifluoroethanol, in sodium N-tris(hydroxymethyl)methyl-3-aminopropanesulfonate buffer at pH 8.2 to 8.6, using polyethylene glycol 4000 as precipitant. X-ray diffraction data to 3.2 A resolution show that the crystals are hexagonal in space group P622 with unit cell dimensions a = b = 147.9 A, c = 69.1 A. There is one subunit of the tetrameric enzyme per asymmetric unit, giving a packing density of 2.9 A3/Da.

Ligand binding kinetics of substance P and neurokinin A receptors stably expressed in Chinese hamster ovary cells and evidence for differential stimulation of inositol 1,4,5-trisphosphate and cyclic AMP second messenger responses

Stably transfected Chinese hamster ovary cells expressing either the substance P receptor or neurokinin A receptor were constructed, isolated, and characterized. Equilibrium ligand binding studies performed on whole cells demonstrated that cell lines expressing either of these receptors contained a single class of high-affinity binding sites with an apparent KD of 0.16 nM for the substance P receptor and an apparent KD of 2.1 nM for the neurokinin A receptor. The higher affinity of substance P for its receptor was accounted for by both a greater association rate constant and a lesser dissociation rate constant. The time course and extent of ligand-stimulated inositol 1,4,5-trisphosphate mass increases in both cell lines were similar and displayed rapid and transient kinetics. Ligand-stimulated cyclic AMP accumulation was also apparent in the cell lines, although the time course and magnitude of the responses were substantially different, with the neurokinin A receptor mediating a greater and more prolonged response. These studies establish the presence of functional substance P receptors and neurokinin A receptors in the stably transfected cell lines and provide evidence for agonist-dependent differential stimulation of second messenger responses.

Structure, functions, and mechanisms of substance P receptor action

Substance P is a member of a family of structurally related peptides, called tachykinins, that are involved in the regulation of many biologic processes. Diversity in the generation of multiple tachykinin peptides arises due to multiple genes encoding these peptides as well as by mechanisms of alternative RNA processing and differential posttranslational processing. The multiple peptides are neurotransmitters and/or neuromodulator substances, and they bring about their actions mainly by activating three primary types of receptors, NK-1, NK-2, and NK-3. The pharmacology and tissue locations of these receptor sites are discussed, as is their involvement in certain biologic responses. These three receptor sites have been molecularly characterized by cDNA cloning and functional expression, and all are members of the superfamily of receptors coupled to G-regulatory proteins. Second messenger systems established to be activated by tachykinin receptor stimulation include the hydrolysis of inositol containing phospholipids by a phospholipase C mechanism. The role of substance P in neurogenic inflammation and plasma extravasation is briefly discussed. The generation of new research tools recently in the tachykinin field should allow for a detailed examination of the mechanisms of peptide action, including a focus on receptor structure-function relations and regulation of receptor sensitivity.

Amyloid-beta peptide, substance P, and bombesin bind to the serpin-enzyme complex receptor

During the formation of an inhibitory complex with neutrophil elastase, alpha 1 antitrypsin (alpha 1 AT) undergoes a structural rearrangement and the resulting alpha 1 AT-elastase complex becomes endowed with chemoattractant activities, mediates an increase in synthesis of alpha 1 AT, and is rapidly cleared from the circulation. In previous studies we have provided evidence that these biological activities involve the recognition of a conformation-specific domain in the alpha 1 AT molecule by a cell surface receptor on human hepatoma HepG2 cells and human monocytes. The receptor has been termed the serpin-enzyme complex (SEC) receptor because it also recognizes complex of serpins antithrombin III, alpha 1 anti-chymotrypsin, and C1 inhibitor with their cognate enzymes. Because a pentapeptide domain of alpha 1 AT (amino acids 370-374, Phe-Val-Phe-Leu-Met) is sufficient for binding to the SEC receptor and the sequence of this domain is remarkably similar to those of substance P, several other tachykinins, bombesin, and the amyloid-beta peptide, we have examined the possibility that these other ligands bind to the SEC receptor. The results indicate that substance P, several other tachykinins, and bombesin compete for binding to, and cross-linking of, the SEC receptor. The SEC receptor is distinct from the substance P receptor by several criteria. There is no substance P receptor mRNA in HepG2 cells; the SEC receptor is present in much higher density on receptor-bearing cells and binds its ligands at lower affinity than the substance P receptor; the SEC receptor is much less restricted in the specificity with which it recognizes ligand; ligands for the SEC receptor including peptide 105Y (based on alpha 1 AT sequence 359-374), alpha 1 AT-protease complexes, and bombesin do not compete for binding of substance P to a stable transfected cell line expressing the substance P receptor. Finally, we show here that the amyloid-beta peptide competes for binding to the SEC receptor but does not bind to the substance P receptor, therein raising the possibility that the SEC receptor is involved in certain biological activities, including the recently described neurotrophic and neurotoxic effects ascribed to the amyloid-beta peptide.

Organization, structure, and expression of the gene encoding the rat substance P receptor

The gene for the rat substance P receptor has been cloned, its genomic structure determined, and the patterns of mRNA expression extensively analyzed. Unlike many genes encoding G protein-coupled receptors, the protein-coding region of this gene is divided into five exons consisting of 965, 195, 151, 197, and 2,010 base pairs. The substance P receptor gene extends more than 45 kilobases in length, and the splice sites for the exons occur at the borders of the sequences encoding putative membrane-spanning domains. The transcription initiation site has been defined by solution hybridization-nuclease protection and nucleotide sequence analyses, and lies downstream of a conventional TATA sequence. Substance P receptor mRNA levels in various tissues have been quantitated using solution hybridization-nuclease protection assays and were found to comprise from 0.00008 to 0.0016% of total RNA levels. Relatively high levels of substance P receptor mRNA are seen in the urinary bladder and the sublingual salivary gland, whereas moderate levels are observed for the submandibular salivary gland, striatum, hippocampus, midbrain, and olfactory bulb with lower levels in the remainder of the central nervous system and alimentary canal. These results are discussed in relation to the evolutionary role of multiple exons for a G protein-coupled receptor and with regard to the locations and mechanisms of substance P receptor gene expression.

Molecular characterization of a functional cDNA encoding the rat substance P receptor

Substance P is a member of the tachykinin peptide family and participates in the regulation of diverse biological processes. The polymerase chain reaction and conventional library screening were used to isolate a complementary DNA (cDNA) encoding the rat substance P receptor from brain and submandibular gland. By homology analysis, this receptor belongs to the G protein-coupled receptor superfamily. The receptor cDNA was expressed in a mammalian cell line and the ligand binding properties of the encoded receptor were pharmacologically defined by Scatchard analysis and tachykinin peptide displacement as those of a substance P receptor. The distribution of the messenger RNA for this receptor is highest in urinary bladder, submandibular gland, striatum, and spinal cord, which is consistent with the known distribution of substance P receptor binding sites. Thus, this receptor appears to mediate the primary actions of substance P in various brain regions and peripheral tissues.

Kinetic characterization of yeast alcohol dehydrogenases. Amino acid residue 294 and substrate specificity

A three-dimensional model of yeast alcohol dehydrogenase, based on the homologous horse liver enzyme, was used to compare the substrate binding pockets of the three isozymes (I, II, and III) from Saccharomyces cerevisiae and the enzyme from Schizosaccharomyces pombe. Isozyme I and the S. pombe enzyme have methionine at position 294 (numbered as in the liver enzyme, corresponding to 270 in yeast), whereas isozymes II and III have leucine. Otherwise the active sites of the S. cerevisiae enzymes are the same. All four wild-type enzymes were produced from the cloned genes. In addition, oligonucleotide-directed mutagenesis was used to change Met-294 in alcohol dehydrogenase I to leucine. The mechanisms for all five enzymes were predominantly ordered with ethanol (but partially random with butanol) at pH 7.3 and 30 degrees C. The wild-type alcohol dehydrogenases and the leucine mutant had similar kinetic constants, except that isozyme II had 10-20-fold smaller Michaelis and inhibition constants for ethanol. Thus, residue 294 is not responsible for this difference. Apparently, substitutions outside of the substrate binding pocket indirectly affect the interactions of the alcohol dehydrogenases with ethanol. Nevertheless, the substitution of methionine with leucine in the substrate binding site of alcohol dehydrogenase I produced a 7-10-fold increase in reactivity (V/Km) with butanol, pentanol, and hexanol. The higher activity is due to tighter binding of the longer chain alcohols and to more rapid hydrogen transfer.

Three rat preprotachykinin mRNAs encode the neuropeptides substance P and neurokinin A

Synthetic oligonucleotides were used to screen a rat striatal cDNA library for sequences corresponding to the tachykinin peptides substance P and neurokinin A. The cDNA library was constructed from RNA isolated from the rostral portion of the rat corpus striatum, the site of striatonigral cell bodies. Two types of cDNAs were isolated and defined by restriction enzyme analysis and DNA sequencing to encode both substance P and neurokinin A. The two predicted preprotachykinin protein precursors (130 and 115 amino acids in length) differ from each other by a pentadecapeptide sequence between the two tachykinin sequences, and both precursors possess appropriate processing signals for substance P and neurokinin A production. The presence of a third preprotachykinin mRNA of minor abundance in rat striatum was established by S1 nuclease protection experiments. This mRNA encodes a preprotachykinin of 112 amino acids containing substance P but not neurokinin A. These three mRNAs are derived from one rat gene as a result of differential RNA processing; thus, this RNA processing pattern further increases the diversity of products that can be generated from the preprotachykinin gene.