Biomedical subjects
Publications and source records attributed to D Daugherty.
Explore the source record for details and available documents.
Recent developments in technology, direct placement restorative materials, and cavity preparation design have renewed interest in kinetic cavity preparation, a term to describe the use of air-abrasion for removal of tooth structure. This study compared the pulpal response of 120 teeth in mixed-breed dogs treated with four kinetic cavity preparation combinations of pressure (80 psi and 160 psi) and aluminum oxide particle sizes (27 microns and 50 microns) to those treated with high-speed rotary burs. Class V buccal preparations were made and restored with an interim material. Teeth were collected 72 hours after surgery, decalcified, sectioned, stained with hematoxylin and eosin, and blindly evaluated by two examiners at the minimal dentin thickness. Samples were graded for extent of displacement, disruption, inflammation, and necrosis of pulpal structures. Differences between groups were analyzed with the use of Bonferroni-adjusted multiple Mann-Whitney-Wilcoxon tests with p < 0.05 being significant. Higher pressures and smaller particles yielded significantly fewer pulpal effects than the high-speed treated teeth whereas lower pressures and larger particles were not significantly different for most effects evaluated. No adverse soft tissue effects were noted when kinetic cavity preparation was directed at attached gingiva.
As is the case with many other peptide hormones of the brain and gut, gastrin requires a carboxyl-terminal amide moiety for optimal biological activity. In the structure of progastrin, the carboxyl-terminal Phe of gastrin is followed by the sequence Gly93-Arg94-Arg95, which must be processed sequentially by an endoprotease, a carboxypeptidase, and an amidating enzyme to produce amidated bioactive gastrin. To examine the molecular determinants of peptide amidation in vivo, we mutated the wild-type Gly93 residue of progastrin to Ala93 and Ser93 and expressed the three progastrin DNAs in GH3 and MTC 6-23 endocrine cell lines. Although substantial quantities of amidated gastrin were seen in cells expressing wild-type progastrin, replacement of Gly93 with Ala93 completely abolished production of amidated gastrin when the cells were incubated in standard medium containing only L-alanine. In a similar fashion, cells expressing [Ser93]progastrin also demonstrated no production of amidated gastrin. When cells expressing [Ala93]- or [Ser93]progastrin were incubated in the presence of 1 mg/ml D-alanine or D-serine, respectively, a small but consistent amount of amidated gastrin production was detected (< 1% of wild type). These data lead us to conclude that the amidating enzyme has a rigid substrate specificity for a glycine-extended precursor. Furthermore, this in vivo substrate specificity confirms the importance of the pro-S-alpha-hydrogen of the carboxyl-terminal glycine for enzyme-substrate recognition.
Biologically active peptide hormones are synthesized from larger precursor proteins by a variety of post-translational processing reactions. To characterize these processing reactions further we have expressed preprogastrin in two endocrine cell lines and examined the molecular determinants involved in endoproteolysis at dibasic cleavage sites. The Gly93-Arg94-Arg95 carboxyl-terminal processing site of progastrin must be processed sequentially by an endoprotease, a carboxypeptidase, and an amidating enzyme to produce bioactive gastrin. For these studies the dibasic Arg94-Arg95 residues that serve as signals for the initiation of this processing cascade were mutated to Lys94-Arg95, Arg94-Lys95, and Lys94-Lys95. In the GH3 cells the Lys94-Arg95 mutation slightly diminished synthesis of carboxyl-terminally amidated gastrin, whereas in the MTC 6-23 cells this mutation had no effect on amidated gastrin synthesis. In contrast, both Arg94-Lys95 and Lys94-Lys95 mutations resulted in significantly diminished production of amidated gastrin in both cell lines. A specific hierarchy of preferred cleavage signals at this progastrin processing site was demonstrated in both cell lines, indicating that cellular dibasic endoproteases have stringent substrate specificities. Progastrins with the Lys94-Arg95 mutation in GH3 cells also demonstrated diminished processing at the Lys74-Lys75 dibasic site, thus single amino acid changes at one processing site may alter cleavage at distant sites. These studies provide insight into the post-translational processing and biological activation of not only gastrin but other peptide hormones as well.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Thirteen adherent human non-lymphocyte cell lines were tested for their susceptibility to infection by human immunodeficiency virus. Productive infection could be demonstrated in three of five colorectal carcinoma cell lines examined; the other eight human non-lymphocyte cell lines were uninfectible. A susceptible colon carcinoma cell line (HT29), as well as normal colonic mucosa, was shown to contain a 3.0-kilobase species of poly(A)+ CD4 RNA, whereas uninfectible colon carcinoma and rhabdomyosarcoma cell lines synthesized no detectable T4 RNA. A persistently infected colon carcinoma cell line was established that continued to produce progeny human immunodeficiency virus for more than 10 weeks postinfection.
Leu-3- cells that survive infection with the acquired immune deficiency syndrome (AIDS) retrovirus can be induced with IUdR to express infectious virus. A cellular clone (8E5), isolated by limiting dilution of a mass culture of survivor cells, was found to contain a single, integrated provirus that was constitutively expressed. Although IUdR treatment of 8E5 cells failed to induce infectious virus, cocultivation with Leu-3+ cells generated the characteristic syncytia associated with acute AIDS retrovirus infection. The single integrated copy of proviral DNA directs the synthesis of all major viral structural proteins except p64, as monitored by immunoblotting. The relationship of the 8E5 clone to viral latency and persistence is discussed.
We studied 68 referred juvenile offspring or siblings of adult bipolar patients. Mean age at onset of affective and related disturbances was 15.9 years (range, 6 to 24 years). Although four of the ten prepubertal children had hypomanic features, full-blown manic psychosis did not appear before puberty. In the sample at large, 12 were classified as dysthymic and ten as cyclothymic. Eleven additional subjects with polysubstance abuse, who at onset did not meet criteria for affective disorder, were reclassified as having either a dysthymic or a cyclothymic disorder during follow-up. Of the remaining patients--24 depressive, eight manic, and three mixed state--71% experienced recurrences; mood-incongruent features, present in four cases at onset, recurred in only one patient during subsequent episodes. Overall, half the sample evidenced signs of bipolarity during a mean prospective follow-up period of three years.
The genome of the human immunodeficiency virus (HIV) contains several open reading frames (ORFs) not present in other viruses. The 'A' gene, also known as Q2 P'3, ORF-1(4) or sor5, partially overlaps the pol gene; its protein product has a relative molecular mass of 23,000 (Mr 23K) and is present in productively infected cells. The function of this protein is unclear; mutant viruses deleted in 'A' replicate in and kill CD4+ lymphocyte lines, but the high degree of conservation of the deduced amino-acid sequence in nine different HIV isolates (80%) and the presence of analogous genes in HIV-2 and other lentiviruses suggest that the gene function is an important one. Here we describe a mutant virus deficient in the 'A' gene which produces virion particles normally; however, the particles are approximately 1,000 times less infective than wild type. Transcomplementation experiments partially restore infectivity. The mutant virus spreads efficiently when virus-producing cells are co-cultivated with CD4+ lymphocytes, however, indicating that HIV can spread from cell to cell in a mechanism that does not require the 'A' gene product and probably does not require the production of infective virus particles.
Abdominal pain occurs commonly in patients with cystic fibrosis, and is the result of a variety of causes, including hepatobiliary disorders. With the increasing duration of survival in these patients, diagnostic investigations for abdominal pain, including hepatobiliary scanning, may be utilized more frequently than in the past. Difficulties in the interpretation of scintigraphic studies may arise because of associated gallbladder anomalies that occur in more than 50% of patients with cystic fibrosis. Hypoplasia of the gallbladder (microgallbladder) occurs commonly. A case is presented in which Tc-99m disofenin hepatobiliary scanning proved diagnostic in a patient with cystic fibrosis and cholelithiasis leading to common bile duct obstruction. The hepatobiliary abnormalities and causes of common bile duct obstruction encountered in cystic fibrosis are reviewed.