Synthesis and platelet aggregation inhibitory activity of 6-isobutyl-alpha-methyl-3-pyridineacetic acid.

2-(4'-Isobutylphenyl)propionic acid, ibuprofen, is an antiinflammatory agent which possesses moderate platelet aggregation inhibitory activity. It was therefore of interest to determine what effect the replacement of the phenyl group of ibuprofen by a 3-pyridyl ring would have on platelet aggregation inhibitory activity. As a result, 6-isobutyl-alpha-methyl-o-pyridineacetic acid (7) and its 2-chloro analogue 13 were synthesized. The key step in the synthesis of 7 and 13 involved the oxidative rearrangement of enol ether 11 to the carboxylic ester 12 with thallium trinitrate. The entire sequences of reactions for the synthesis of compounds 7 and 13 are described in detail. Platelet aggregation inhibitory evaluation of 7 and 13 showed 7 to possess activity equivalent to ibuprofen; however, 13 was devoid of platelet aggregation inhibitory activity at an equivalent dose.

Synthesis and platelet aggregation inhibitory activity of 4,5-bis(aryl)-2-substituted-thiazoles.

In our continuing effort to discover compound which inhibit collagen-induced platelet aggregation, we have screened compounds in a mouse pulmonary thromboembolism screen. Methyl 4,5-bis(4-methoxyphenyl)-2-thiazoleacetate (3) was very active in the above screen. However, 3 was active for less than 5 min when given orally to guinea pigs. As a result, our synthetic goal was to prepare 2-substituted thiazoles with a much longer duration of activity. This paper describes the preparation of a number 4,5-bis(aryl)-2-substituted-thiazoles and their in vitro and ex vivo activity against collagen-induced platelet aggregation. It was determined that 4,5-bis(4-methoxyphenyl)-2-(trifluoromethyl)thiazole (16) is the most promising compound.

A thiazole compound with potential antithrombotic activity.

A thiazole derivative, 4,5-bis(p-methoxyphenyl)-2-(trifluoromethyl)-thiazole was found to be a potent inhibitor of collagen-induced platelet aggregation, in vitro, using platelets from at at least six species, including man. It was active in human platelet-rich plasma at a concentration of 1 ng/ml. While its antiplatelet activity was greater than that of flurbiprofen, its cyclooxygenase activity was equivalent to that of flurbiprofen. Also, compared to flurbiprofen, the thiazole had less anti-inflammatory activity in the hind-paw edema test. The thiazole derivative inhibited platelet aggregation following oral administrative inhibited platelet aggregation following oral administration in five laboratory species. In the guinea pig it was active at 0.5 mg/kg. The LD50 in mice was greater than 1000 mg/kg (i.p.). This compound, which was designed through a systematic drug development program, may have high potential as an antithrombotic agent.

Compliance with supportive periodontal therapy.

All new patients commencing supportive periodontal therapy (periodontal maintenance) after treatment in a specialist periodontal practice from 1983 to 1986 were identified from practice records. Based on their compliance with the recommended schedule of visits, the patients were classified as either compliant or non-compliant. The results indicated that there were no significant differences between compliant and non-compliant patients with regards to age, sex, number of missing teeth, plaque score, or periodontal disease severity. More non-compliant patients than compliant patients were smokers (P less than 0.05). By contrast, more compliant patients were covered by private dental insurance (P less than 0.01) and more had periodontal surgery during treatment (P less than 0.001). Only 36% of the initial patient sample was found to be compliant at the end of 1989, with the greatest patient loss in the first year of supportive periodontal therapy of about 42%. The annual attrition rate decreased in subsequent years to average about 10% of those remaining in each year, indicating that a patient is more likely to remain compliant if he or she attends for at least 1 year of supportive periodontal treatment. Non-compliant patients were sent a questionnaire seeking reasons for their non-compliance. Forty percent of the questionnaires were returned. The most common reason given for non-compliance was that a general dental practitioner was attending to the patient's periodontal treatment needs. Many considered supportive periodontal therapy to be too expensive, while a significant proportion considered that they no longer required treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Visualization of the maxillary sinus and styloid processes using rotational panoramic radiography.

A technique is presented which improves visualization of the medio-lateral aspect of the maxillary sinus using rotational panoramic radiography. The method was also assessed for accuracy of styloid process projection. Using a specially constructed Perspex stand, dried skulls of varying ages were radiographed in various reproducible positions using a panoramic unit. The best medio-lateral view of the maxillary sinus of adult skulls was achieved by: (1) raising the height of the film approximately 20 mm in relation to the subject; (2) moving the subject 15-20 mm forward of the standard position for a panoramic view for adults (10-15 mm for children); and (3) tilting the occlusal plane downwards approximately 8-10 degrees. The styloid processes were readily seen using this maxillary sinus view. The resultant image of the process was elongated by a factor of 1.24 +/- 0.02 by this technique.

The split denture: a new technique for artificial saliva reservoirs in mandibular dentures.

Xerostomia is a relatively common complaint that can make the wearing of dentures very uncomfortable for affected individuals. To help overcome this problem, a number of techniques have been proposed for incorporating reservoirs, containing salivary substitutes, into dentures. These have had varying degrees of success. This paper presents a case of a patient suffering from xerostomia who was successfully treated with a new form of reservoir denture. This new split-denture technique resulted in a reservoir denture that provided good lubrication of the oral tissues, was easily cleaned by the wearer and was produced from routine denture materials. Details of its design, construction and other potential applications are also presented.

Panoramic ghost images as an aid in the localization of soft tissue calcifications.

Mapping of the ghost envelope for an Orth Oralix panoramic x-ray unit (Philips Medical Systems) was carried out with a lead sphere suspended at various locations around a dry mandible. The ghost envelope is a three-dimensional zone within which an object or anatomic structure must lie to produce a ghost image on panoramic radiographs. If the three-dimensional shape of the ghost envelope for a particular panoramic unit is known, information can be gained about the clinical location of objects appearing on radiographs produced with that machine. Objects outside the envelope will not result in ghost image formation. Objects within the envelope will result in characteristic ghost images depending on their position. This article analyzes ghost image characteristics in relation to object position and discusses the limitations of the method. A series of ready reference diagrams is provided, which may aid in the localization of soft tissue calcifications and foreign objects observed on panoramic radiographs.

Complement component C4 gene intron 9 as a phylogenetic marker for primates: long terminal repeats of the endogenous retrovirus ERV-K(C4) are a molecular clock of evolution.

The complement component C4 genes of Old World primates exhibit a long/short dichotomous size variation, except that chimpanzee and gorilla only contain short C4 genes. In human it has been shown that the long C4 gene is attributed to the integration of an endogenous retrovirus, HERV-K(C4), into intron 9. This 6.36 kilobase retroviral element is absent in short C4 genes. Here it is shown that the homologous endogenous retrovirus, ERV-K(C4), is present precisely at the same position in the long C4 gene of orangutan and African green monkey. Determination of the short C4 gene intron 9 sequences from human, three apes, two Old World monkeys, and a New World monkey allowed the establishment of consistent phylogenetic trees for primates, which favors a chimpanzee-gorilla clade. The 5' long terminal repeats (LTR) and 3' LTR of ERV-K(C4) in long C4 genes of human, orangutan, and African green monkey have similar sequence divergence values of 9.1%-10.5%. These values are more than five-fold higher than the sequence divergence of the homologous intron 9 sequences between the long and short C4 genes in higher primates. The latter is probably a result of homogenization or concerted evolution. We suggest that the 5' LTR and 3' LTR of an endogenous retrovirus can serve as a reliable reference point or a molecular clock for studies of gene duplication and gene evolution. This is because the 5'/3' LTR sequences were identical at the time of retroviral integration and evolved independently of each other afterwards. Our data provides strong evidence for the short C4 gene being the ancestral form in primates, trans-species evolution, and the "slow-down" phenomenon of the sequence divergence in great apes.

Human helicase gene SKI2W in the HLA class III region exhibits striking structural similarities to the yeast antiviral gene SKI2 and to the human gene KIAA0052: emergence of a new gene family.

Helicases are essential enzymes for life because DNA replication, DNA repair, recombination, transcription, RNA splicing and translation all involve more than one helicase to unwind DNA or RNA. We have discovered, cloned and partially characterized a novel human helicase gene, SKI2W. The human SKI2W is located between the RD and RP1 genes in the class III region of the major histocompatibility complex (MHC) on chromosome 6, a genomic region associated with many malignant, genetic and autoimmune diseases. Derived amino acid sequence of human SKI2W showed an open reading frame for 1246 residues. It contains consensus sequences for structural motifs of an RNA helicase with a DEVH box. It has a leucine zipper motif that may be important for protein dimerization, and an RGD motif close to the N-terminus that might serve as a ligand for integrin or cell adhesion molecules. SKI2W shares a striking and extensive similarity to the yeast Ski2p that is involved in the inhibition of translation of poly(A) negative [poly(A)-] RNA, and plays an important role in antiviral activities. Human SKI2W fusion protein expressed in insect cells using a baculovirus vector has ATPase activity. The human SKI2W protein and the yeast Ski2p share extensive sequence similarities to another putative human protein KIAA0052, suggesting the presence of a new gene family that may be involved in translational regulation of cellular and viral RNA.

Modular variations of the human major histocompatibility complex class III genes for serine/threonine kinase RP, complement component C4, steroid 21-hydroxylase CYP21, and tenascin TNX (the RCCX module). A mechanism for gene deletions and disease associations.

The frequent variations of human complement component C4 gene size and gene numbers, plus the extensive polymorphism of the proteins, render C4 an excellent marker for major histocompatibility complex disease associations. As shown by definitive RFLPs, the tandemly arranged genes RP, C4, CYP21, and TNX are duplicated together as a discrete genetic unit termed the RCCX module. Duplications of the RCCX modules occurred by the addition of genomic fragments containing a long (L) or a short (S) C4 gene, a CYP21A or a CYP21B gene, and the gene fragments TNXA and RP2. Four major RCCX structures with bimodular L-L, bimodular L-S, monomodular L, and monomodular S are present in the Caucasian population. These modules are readily detectable by TaqI RFLPs. The RCCX modular variations appear to be a root cause for the acquisition of deleterious mutations from pseudogenes or gene segments in the RCCX to their corresponding functional genes. In a patient with congenital adrenal hyperplasia, we discovered a TNXB-TNXA recombinant with the deletion of RP2-C4B-CYP21B. Elucidation of the DNA sequence for the recombination breakpoint region and sequence analyses yielded definitive proof for an unequal crossover between TNXA from a bimodular chromosome and TNXB from a monomodular chromosome.

Structure and genetics of the partially duplicated gene RP located immediately upstream of the complement C4A and the C4B genes in the HLA class III region. Molecular cloning, exon-intron structure, composite retroposon, and breakpoint of gene duplication.

The correlation of many HLA-associated autoimmune and genetic diseases with the polymorphic complement C4 genes may be attributed to the presence of disease susceptibility genes in the close proximity of C4. We have cloned and characterized a pair of partially duplicated genes, RP1 and RP2, located 611 base pairs upstream of the human C4A and C4B genes, respectively. The putative RP protein, consisting of 364 amino acid residues, is basic and highly hydrophilic. There is a bipartite nuclear localization signal at residues 114-131 and therefore RP may be a nuclear protein. Northern blot analysis suggested that RP is ubiquitously expressed. The 5' region of the RP1 gene is CpG rich, which is a characteristic of housekeeping genes. The RP1 gene contains nine exons. Located in the fourth intron is a cluster of Alu elements, and a newly defined composite retroposon SVA with a SINE, multiple copies of GC-rich VNTRs and an Alu element altogether enclosed by direct terminal repeats. Members of SVA are also present in the complement C2 gene located about 20 kilobases upstream of RP1 in the HLA and in the cytochrome CYP1A1 gene. Determination of the DNA sequences for RP2 from two different HLA haplotypes revealed identical hybrid sequences which resulted from fusion of RP with the tenascin-like Gene X and truncation of the 5' regions of both genes. Cumulative data suggest that the four tandemly arranged genes RP, complement C4, steroid 21-hydroxylase (CYP21), and Gene X altogether form a modular structure, RCCX. The number of RCCX modules varies from one to three or more in the population. Absence of the truncated genes RP2 and Gene XA have been detected in genomes with single RCCX modules. Duplication of the RCCX modules probably occurred before the speciation of great apes and humans as they contain the same breakpoint region of RP and Gene X gene duplication.

The dichotomous size variation of human complement C4 genes is mediated by a novel family of endogenous retroviruses, which also establishes species-specific genomic patterns among Old World primates.

The human complement C4 genes in the HLA exhibit an unusual, dichotomous size polymorphism and a four-gene, modular variation involving novel gene RP, complement C4, steroid 21-hydroxylase (CYP21), and tenascin-like Gene X (RCCX). The C4 gene size dichotomy is mediated by an endogenous retrovirus, HERV-K(C4). Nearly identical sequences for this retrotransposon are present precisely at the same location in the long C4 genes from the tandem RCCX Module I and Module II. Specific nucleotide substitutions between the long and short C4 genes have been identified and used for diagnosis. Southern blot analyses revealed that HERV-K(C4) is present at more than 30 locations in the human genome, exhibits variations in the population, and its analogs exist in the genomes of Old World primates with species-specific patterns. Evidence of intrachromosomal recombination between the two long terminal repeats of HERV-K(C4) is found near the huntingtin locus on chromosome 4. It is possible that members of HERV-K(C4) are involved in genetic instabilities including the RCCX modules, and in protecting the host genome from retroviral attack through an antisense strategy.