De novo expansion of a (CAG)n repeat in sporadic Huntington's disease.

Huntington's disease (HD) chromosomes contain an expanded unstable (CAG)n repeat in chromosome 4p16.3. We have examined nine families with potential de novo expression of the disease. With one exception, all of the affected individuals had 42 or more repeat units, well above the normal range. In four families, elderly unaffected relatives inherited the same chromosome as that containing the expanded repeat in the proband, but had repeat lengths of 34-38 units, spanning the gap between the normal and HD distributions. Thus, mutation to HD is usually associated with an expansion from an already large repeat.

A DNA segment encoding two genes very tightly linked to Huntington's disease.

The discovery of D4S10, an anonymous DNA marker genetically linked to Huntington's disease (HD), introduced the capacity for limited presymptomatic diagnosis in this late-onset neurodegenerative disorder and raised the hope of cloning and characterizing the defect based on its chromosomal location. Progress on both fronts has been limited by the absence of additional DNA markers closer to the HD gene. An anonymous DNA locus, D4S43, has now been found that shows extremely tight linkage to HD. Like the disease gene, D4S43 is located in the most distal region of the chromosome 4 short arm, flanked by D4S10 and the telomere. In three extended HD kindreds, D4S43 displays no recombination with HD, placing it within 0 to 1.5 centimorgans of the genetic defect. Expansion of the D4S43 region to include 108 kilobases of cloned DNA has allowed identification of eight restriction fragment length polymorphisms and at least two independent coding segments. In the absence of crossovers, these genes must be considered candidates for the site of the HD defect, although the D4S43 restriction fragment length polymorphisms do not display linkage disequilibrium with the disease gene.

Recombination events suggest potential sites for the Huntington's disease gene.

The Huntington's disease gene (HD) maps distal to the D4S10 marker in the terminal 4p16.3 subband of chromosome 4. Directed cloning has provided several DNA segments that have been grouped into three clusters on a physical map of approximately 5 X 10(6) bp in 4p16.3. We have typed RFLPs in both reference and HD pedigrees to produce a fine-structure genetic map that establishes the relative order of the clusters and further narrows the target area containing the HD gene. Despite the large number of meiotic events examined, the HD gene cannot be positioned relative to the most distal cluster. One recombination event with HD suggests that the terminal-most markers flank the disease gene; two others favor a telomeric location for the defect. Efforts to isolate the HD gene must be divided between these two distinct intervals until additional genetic data resolve the apparent contradiction in localization.

Clustering of multiallele DNA markers near the Huntington's disease gene.

Five highly informative multiallele restriction fragment length polymorphisms (RFLPs) of value for preclinical diagnosis of Huntington's disease (HD) have been genetically characterized. One RFLP was uncovered by expansion of the D4S43 locus while three others are at D4S111 and D4S115, loci defined by NotI-linking clones. The final marker, D4S125, represents a recently discovered VNTR locus. All four loci map closer to the HD gene and to the telomere than D4S10, the original linked marker for HD. In combination with two multiallele RFLPs previously identified for D4S43 and another linked locus, D4S95, these five new multiallele markers will dramatically improve the speed and accuracy of predictive testing in HD, and increase its applicability by maximizing the chances of an informative test for anyone with appropriate family structure.

Oral ondansetron for the control of cisplatin-induced delayed emesis: a large, multicenter, double-blind, randomized comparative trial of ondansetron versus placebo.

PURPOSE: To investigate the efficacy and safety of oral ondansetron in the control of cisplatin-induced delayed emesis in patients who do not require rescue antiemetic therapy for acute emesis. PATIENTS AND METHODS: Five hundred thirty-eight chemotherapy-naive patients who received cisplatin chemotherapy (> or = 70 mg/m2), and who were not rescued for acute emesis, were eligible to be randomized to receive one of the three oral regimens to control delayed emesis. Group I received placebo on days 2 to 6; group II received ondansetron 8 mg twice daily on days 2 and 3 and placebo on days 4 to 6; group III received ondansetron 8 mg twice daily on days 2 to 6. All patients received intravenous ondansetron (0.15 mg/kg every 4 hours for three doses) for the control of acute emesis on day 1. The number of emetic episodes on days 2 and 3 combined (days 2/3, when incidence and severity of delayed emesis were expected to be greatest) was considered the primary measure of efficacy. RESULTS: Patients who received odansetron had significantly fewer emetic episodes on days 2/3, 4, and 5 than those who received placebo (P < or = .002 on each day). Additionally, significantly more patients who received ondansetron had a complete plus major response (C+MR; < or = two two emetic episodes) than those who received placebo on days 2/3 (56% v 37%, P = .001), 4 (94% v 85%, P = .005), and 5 (98% v 88%, P = .006). Patients who received ondansetron had significantly less nausea on day 2/3 when day-1 nausea was used as the baseline score (P = .025). Patients who received ondansetron also had significantly less nausea on day 4 (P = .042) and the results approached significance on day 5 (P = .066). CONCLUSION: Oral ondansetron had a significant effect in the control of cisplatin-induced delayed emesis and nausea in patients who had not required rescue antiemetics during the acute emesis period. The control of delayed nausea and vomiting was most notable in the immediate 2 days following cisplatin administration, with the clinical difference narrowing between the two treatment arms on subsequent days.

A Comparison of Oral Ondansetron and Intravenous Granisetron for the Prevention of Nausea and Emesis Associated with Cisplatin-Based Chemotherapy.

PURPOSE: To compare the efficacy and safety of oral ondansetron with i.v. granisetron each given as a single dose prior to administration of highly emetogenic cisplatin chemotherapy. PATIENTS AND METHODS: Chemotherapy-naive patients with histologically confirmed malignancies were randomized to receive a single 24 mg ondansetron hydrochloride tablet plus a 50 ml i.v. infusion of normal saline, or a single 10 µg/kg (50 ml) i.v. infusion of granisetron plus a placebo tablet in this multicenter, double-blind, parallel-group trial. Study drug was administered 30 min prior to a single i.v. infusion of cisplatin (50-75 mg/m²), given over a period of

Opiate binding sites in the cellular immune system: expression and regulation.

The direct actions of opiates on the mammalian immune system depend on the existence of ligand binding sites either on the surface of the affected cell or in the interior of the cell. With the cloning of various opiate receptors from neuronal tissue, numerous researchers have screened leukocyte cDNA libraries for the expression of these receptors with some positive results. However, the pattern of expression of neuronal opiate receptors in the cellular immune system does not completely explain the biological action of opiates there. Several possibilities could account for this non-congruence including differential expression of the receptors as determined by such factors as cell population or prior history of the cells; the existence of sequence modified versions of the neuronal receptors such that the amplification methods miss their presence; or the opiates act by a different, non-receptor mechanism in the cellular immune system.

The morphine-binding site on human activated T-cells is not related to the mu opioid receptor.

Mitogen activation of human T-lymphocytes induces a morphine-binding site. Morphine binding is displaceable by beta-endorphin (1--31) and (--)-naloxone but not DAMGO. This site is not stereoselective for (--)-morphine. T-lymphocytes, expressing this binding site, were assayed by reverse-transcription polymerase chain reaction (RT-PCR) for expression of hMOR-1 mRNA. Several primer sets were used and each assay compared with cells known to express human or mouse MOR-1 mRNA. Neither hMOR-1 nor any homologous receptor was detected in human T-lymphocytes. Therefore, the morphine-binding site on mitogen-activated T-lymphocytes is unlikely to be closely related to hMOR-1.

Atlantoaxial dislocation and Down's syndrome.

The phenotypic features of Down's syndrome are easily recognized and include characteristic facial features, hypotonia, ligament laxity, transverse palmar creases and mental subnormality. Associated manifestations and complications are also familiar and involve almost every organ system. Congenital heart defects, bowel malformations and a tendency to leukemia are common attendant problems. Less common, however, are defects of the skeletal system; in fact, the most recent edition of a standard pediatric textbook makes no mention of anomalies of the vertebral column. The purpose of this paper is to call attention to the association between Down's syndrome and atlantoaxial dislocation, which in our patient resulted in quadriplegia and eventually death.

Oncornavirus modification of the Golgi apparatus.

Two virus system, The Friend leukaemia virus (FLV) and the Rous sarcoma virus (RSV), were introduced into tissue both in vitro and in vivo. Both brought about substantial modification of the activity of the Golgi apparatus detectable as such by specific radioautographic studies. This modification was accompanied by changes in the development and social behaviour of the cells with some differences being detectable between the in vivo and in vitro studies.

Gramicidin K, a new linear channel-forming gramicidin from Bacillus brevis.

A new gramicidin has been isolated from a commercial mixture of gramicidins A, B, and C. This new molecule, designated gramicidin K, contains formyl and ethanolamine blocking groups, has a molecular weight approximately 20% higher than gramicidin A, and is strongly retained on reversed-phase liquid chromatographic columns. Gramicidin K can be resolved into two components, one of which contains tyrosine. In lipid bilayer membranes, both components form channels of considerably longer lifetime and somewhat lower conductance than gramicidin A. Gramicidin K appears to be a lipopeptide that consists of a fatty acyl chain attached to the ethanolamine of gramicidin A.

Equilibrium binding constants for the group I metal cations with gramicidin-A determined by competition studies and T1+-205 nuclear magnetic resonance spectroscopy.

The equilibrium binding constants of the Group I metal cations with gramicidin A in aqueous dispersions of lyso-PC have been determined using a combination of competitive binding with the T1+ ion and T1-205 NMR spectroscopy. The values of the binding constants at 34 degrees C are Li (32.2 M-1), Na (36.9 M-1), K (52.6 M-1), Rb (55.9 M-1), and Cs (54.0 M-1). The equilibrium binding constant for the T1+ ion at this temperature is 582 M-1. The relationships between the binding constants, the free energy of the binding process, and the cation selectivity of the gramicidin A channel are discussed.

Equilibrium binding constants for Tl+ with gramicidins A, B and C in a lysophosphatidylcholine environment determined by 205Tl nuclear magnetic resonance spectroscopy.

Nuclear Magnetic Resonance (NMR) 205Tl spectroscopy has been used to monitor the binding of Tl+ to gramicidins A, B, and C packaged in aqueous dispersions of lysophosphatidylcholine. For 5 mM gramicidin dimer in the presence of 100 mM lysophosphatidylcholine, only approximately 50% or less of the gramicidin appears to be accessible to Tl+. Analysis of the 205Tl chemical shift as a function of Tl+ concentration over the 0.65-50 mM range indicates that only one Tl+ ion can be bound by gramicidin A, B, or C under these experimental conditions. In this system, the Tl+ equilibrium binding constant is 582 +/- 20 M-1 for gramicidin 1949 +/- 100 M-1 for gramicidin B, and 390 +/- 20 M-1 for gramicidin C. Gramicidin B not only binds Tl+ more strongly but it is also in a different conformational state than that of A and C, as shown by Circular Dichroism spectroscopy. The 205Tl NMR technique can now be extended to determinations of binding constants of other cations to gramicidin by competition studies using a 205Tl probe.

TI-205 nuclear magnetic resonance determination of the thermodynamic parameters for the binding of monovalent cations to gramicidins A and C.

Thermodynamic parameters for the binding of the monovalent cations, Li+, Na+, K+, Rb+, Cs+, NH4+, TI+, and Ag+, to gramicidin A and for the binding of TI+ to gramicidin C, incorporated into lysophosphatidylcholine, have been determined using a combination of TI-205 nuclear magnetic resonance spectroscopy and competition binding. The thermodynamic parameters, enthalpy and entropy, are discussed in terms of a process involving the transfer of cations from an aqueous to amide environment.