Biomedical subjects
Publications and source records attributed to A M Harris.
A 25-year-old male, with Marfan's syndrome, had asymptomatic atrial fibrillation. Echocardiography revealed an interatrial septal aneurysm. Electrical cardioversion restored sinus rhythm. Relevant aspects of interatrial septal aneurysm are reviewed.
Anecdotal reports of bracket fracture and tooth damage associated with the use of certain esthetic orthodontic brackets have been reported in the literature. With the advent of new esthetic orthodontic brackets, the need has arisen to test the claims of the manufacturers. The objectives of this study were to determine: (1) shear peel bond strengths (SPBS) of various debonded orthodontic brackets, (2) SPBS of these rebonded esthetic brackets with and without use of silane, and (3) fracture sites of all groups examined. Seventy-five noncarious human premolar teeth were randomly divided into five groups (A through E). The teeth were cleaned, stored in 70% ethyl alcohol, and mounted for testing in the Instron machine. The following brackets were bonded to the teeth with Ortho-Concise bonding resin: (A) metal brackets, (B) Silkon brackets, (C) Transcend 2000 brackets, (D) debonded Transcend 2000 brackets, and (E) debonded silanized Transcend 2000 brackets. After wet storage at 37 degrees C for 7 days, the SPBS of brackets were recorded, and fracture sites observed. There were statistically significant differences between the SPBS of metal brackets when compared with the Transcend 2000 and the Silkon brackets. These groups exhibited clinically acceptable SPBS. Debonded silanized Transcend 2000 brackets showed clinically unacceptable SPBS. Fracture sites of metal and Transcend 2000 brackets were resin-bracket, whereas Silkon brackets fracture sites were predominantly resin-enamel.
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Three attenuated Salmonella typhi strains have been constructed by introducing deletions in aroC and aroD or deletions in cya and crp into one of two wild-type parent strains, Ty2 or ISP1820. These mutant strains were designated CVD 906 (ISP1820 delta aroC delta aroD), CVD 908 (Ty2 delta aroC delta aroD), and chi 3927 (Ty2 delta cya delta crp). Two studies were conducted with 36 healthy adult inpatient volunteers to determine in a double-blind fashion the safety and immunogenicity of approximately 5 x 10(4) and 5 x 10(5) CFU of each of these three vaccine candidates given as a single dose. No statistically significant difference in the incidence of reactions among vaccinees was observed. Fever (oral temperature greater than or equal to 38.2 degrees C) occurred in 2 of 12 volunteers who received CVD 906, in 0 of 12 who received CVD 908, and in 1 of 12 who received chi 3927. Vaccine bacteremia without symptoms occurred in 1 of 12 vaccinees who received CVD 906, in 0 of 12 who received CVD 908, and in 2 of 12 who received chi 3927. Overall, 19 (53%) of 36 vaccinees developed immunoglobulin G antibody to S. typhi lipopolysaccharide after vaccination, with no statistically significant differences in the rate of seroconversion among volunteers in the three groups. We conclude that defined mutations in the aromatic biosynthetic pathway and in the cyclic AMP global regulatory system attenuate S. typhi. Mutant strains CVD 906, CVD 908, and chi 3927 are highly (and approximately equally) immunogenic but possibly differ in their propensity to induce fever. Further studies are needed to document the apparent relative safety of CVD 908 as a typhoid vaccine and as a vaccine carrier of foreign antigens.
Candidate vector vaccine strain CVD 906 (aroC- and aroD- derivative of virulent Salmonella typhi strain ISP1820) was evaluated in phase 1 clinical trials. The first nine volunteers ingested a single dose of 5 x 10(7) CVD 906 bacilli. At this dose CVD 906 stimulates remarkable systemic and mucosal immune responses, inasmuch as 89% of volunteers developed marked serum antibody levels to S. typhi antigens and high numbers of antigen-specific gut-derived antibody-secreting cells. Four (44%) volunteers developed asymptomatic vaccinemia 4-10 d after immunization and all volunteers excreted CVD 906 on at least one occasion. However, two volunteers developed febrile adverse reactions, one on the day of vaccination and the other on day 4. Of 11 volunteers who ingested a single dose of 5 x 10(3) CVD 906 bacilli, none displayed side effects but 27% developed significant serum responses to S. typhi LPS. In vitro, CVD 906 replicates for only nine generations in pooled human serum, indicating that CVD 906 growth is limited in this physiologically relevant medium. In phorbol myristate acetate-induced U937 human macrophage-like cells, CVD 906 replicates intracellularly to a lesser extent than parent strain ISP1820. Although, strain CVD 906 is attenuated and highly immunogenic, the occasional febrile reactions at high doses indicate that further attenuation of this strain is necessary.
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The reduction of dietary cholesterol and fat lowers low-density lipoprotein cholesterol (LDL-C) and reduces risk of coronary heart disease in adults. The purpose of this study was to determine the individual variability of response of serum lipid and lipoprotein levels to a low-fat, low-cholesterol diet in children with elevated LDL-C levels. Thirty-two children (2 to 16 years of age) enrolled in a diet modification program, who had LDL-C levels of at least 110 mg/dL but normal triglyceride levels for their ages, were studied. Lipid levels and dietary nutrients were analyzed at the time of admission, and final assessments were made at least 3 months after entry. There was a significant correlation, for the group as a whole, between change in LDL-C concentration and change in grams of dietary saturated fat; however, there was marked individual variability in LDL-C response. There were no significant correlations between changes in LDL-C levels and changes in either total fat, polyunsaturated fat, or cholesterol intake. It is concluded that modest decreases in dietary saturated fat coincide with a lowering of LDL-C concentration, over a short term, in many children, but the degree of lowering varies considerably from one child to another. This variability is consistent with the concept that response of serum lipid levels to dietary changes is modified by genetic, metabolic, and other, as of yet, undefined variables.
We have characterized several of the cytocidal effector functions of a series of cell lines derived by recombinant retroviral transformation of individual clones of C3H/HeJ mouse splenic macrophages. The three cell lines described in this report (4.01, 4.07, 4.14) all expressed equivalent tumoricidal activity against P815 tumor target cells. However they differed in their high avidity binding of tumor cells (4.01 = 4.14 greater than 4.07), as well as in the killing of Leishmania major (4.01 = 4.07 greater than 4.14), the expression of antibody-dependent cellular cytotoxicity against chicken erythrocytes (4.14 greater than 4.01 greater than 4.07), and finally, in the tumor-stimulated release of tumor necrosis factor-alpha (4.01 = 4.14 greater than 4.07). The stable and restricted expression of distinct effector functions among these three cell lines makes them particularly valuable as models for establishing the precise mechanisms by which cytocidal functions are effected. In addition, they should also prove of value in understanding the basis for macrophage functional diversity.
A tissue-equivalent anthropomorphic human phantom was used with a lithium fluoride thermoluminescent dosimetry system to evaluate the radiation absorbed dose to the ovarian and testicular region during dental radiologic procedures. Measurements were made with and without personal lead shielding devices consisting of thyroid collar and apron of 0.25 mm lead thickness equivalence. The radiation absorbed dose with or without lead shielding did not differ significantly from control dosimeters in vertex occlusal and periapical views (p greater than 0.05). Personal lead shielding devices did reduce gonadal dose in the case of accidental exposure (p less than 0.05). A leaded apron of 0.25 mm lead thickness equivalent was permeable to radiation in direct exposure testing.
The construction of genetically defined, double aro mutant strains CVD906 and CVD908, which were derived from Salmonella typhi strain ISP1820 (a recent isolate of S. typhi from Chile) and from laboratory strain Ty2, respectively, is described. Strains CVD906 and CVD908 differ from previously described aro mutants of S. typhi as their aro deletion mutations do not extend beyond the limits of the mutated aro genes, and no antibiotic-resistance genes, plasmid sequences or S. typhimurium DNA sequences remain in the mutant strains. In minimal medium the aro mutants of S. typhi are unable to replicate whereas the wild type parent strains grow well in minimal medium. Using intraperitoneal inoculation of mice with S. typhi strains suspended in hog gastric mucin as a virulence assay, it is shown that the single aro mutants and the double aro mutants of Ty2 and ISP1820 are attenuated in mice. Trans complementation of the aro mutants with the aroC gene or aroD gene, or both, results in strains that are phenotypically identical to that of the wild type parents indicating that no measurable additional changes other than loss of the aro gene function occurred during strain construction.
The skeletal growth patterns of 103 subjects with Class I and III malocclusions were cephalometrically analyzed as advocated by Ricketts el al. to assess abnormal mandibular growth. The surface area (mm2) of the frontal sinus was assessed by a Summagraphics decoder linked to a microcomputer. The results indicate that there is a significant correlation between maxillary length, mandibular length, symphysis width, condylar length, and frontal sinus size on a lateral cephalogram. The frontal sinus can possibly be used as an additional indicator when one is predicting mandibular growth.
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An in-vitro model was shown to be capable of simulating a cefuroxime serum profile equivalent to that observed in human volunteer studies, following a single dose of 250 mg cefuroxime axetil. The model was used to carry out kill kinetic studies and showed cefuroxime to lyse the four bacterial test strains, time of onset of lysis being related to the sensitivity of the respective organisms. The more sensitive Staphylococcus aureus and Haemophilus influenzae strains were subject to a higher absolute kill and showed no regrowth over the duration of the simulated serum profile. In contrast, Proteus mirabilis and Escherichia coli showed regrowth after 4 and 5 h respectively. The kill kinetic profiles of the respective organisms are discussed in relation to the pharmacokinetic analysis of the cefuroxime serum profile.
GR69153 is a novel cephalosporin incorporating a catechol-substituted 7-aminothiazolyl-oxime. The antibiotic is actively transported into gram-negative cells via iron-regulated outer membrane proteins regulated by the tonB product. This transport enhances bactericidal activity most significantly at low concentrations, essentially removing the permeability barrier for antibiotic uptake.
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