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Robert L Boyd

Publications and source records attributed to Robert L Boyd.

8 recordsLinked to original sources

An update on present and future considerations of aligners.

This report reviews the orthodontic treatment of six different patients who received removable aligners. These cases include correction of deep overbite, open bite, mild-to-moderate crowding, large overjet, cases requiring premolar extractions, the presence of multiple restorations, and cases requiring periodontal-restorative treatments, the improved periodontal status with aligners compared to fixed appliances and the use in teenagers. This report demonstrates that a wide range of cases can be effectively treated, provided the cases are thoroughly reviewed at an early stage process using Invisalgn's ClinCheck software, which will show the specific details of all consecutive appliances prior to any treatment being started so as to determine the biologic and biochemical feasibility of treatment.

Adolescent↗

Pacific Craniofacial Team and Cleft Prevention Program.

There is no doubt modern genetics have greatly influenced our professional and personal lives during the last decade. Uncovering genetic causes of many medical and dental pathologies is helping to narrow the diagnosis and select a treatment plan that would provide the best outcome. Importantly, having an understanding of multifactorial etiology helps direct our attention toward prevention. We now understand much better our own health problems. In some cases, we can modify our lifestyle and diet in order to prevent "environmental factors" from triggering the mutated genes inherited from our parents. Good examples are diabetes and cardiovascular diseases. If we realize we might have inherited genes for cardiovascular problems from several ancestors who had heart attacks, we already know that these genes will make us only "susceptible" for disease. Those who exercise, watch one's weight, diet, and carefully monitor one's lifestyle will very likely--though possessing "susceptibility genes"--stay healthier and, maybe, will never experience any cardiovascular problems. In principle, the same applies for craniofacial anomalies, especially for nonsyndromic cleft lip and palate. One needs to understand genetic and environmental causes of nonsyndromic orofacial clefts in order to prevent them. With all this in mind, the Pacific Craniofacial Team and Cleft Prevention Program have been established at the Department of Orthodontics, University of the Pacific Arthur A. Dugoni School of Dentistry in San Francisco. A partnership with Rotaplast International, Inc., has made it possible for the faculty, orthodontic residents, and students to participate in 27 multidisciplinary cleft medical missions in underdeveloped and developing countries by donating professional and educational services, and, last but not least, by collecting valuable data and specimens to further research. A significant number of research studies, including 15 master of science theses, have been accomplished in UOP's Craniofacial Genetics Laboratory, with contributions by faculty, undergraduate and graduate students. It has been leading to a better understanding of etiology of nonsyndromic orofacial clefts. It has been learned that genetic factors and environmental factors are ethnicity-specific and, in many places throughout the world, location-specific. Thus, a specific protocol for cleft prevention has to be worked out based on genetic and nutritional studies of each specific population group in order to be effective. This is our ultimate goal.

California↗

Phase II study of fludarabine and alpha-interferon in patients with low-grade non-Hodgkin's lymphoma.

BACKGROUND AND OBJECTIVES: Low-grade non-Hodgkin's lymphoma (NHL) remains incurable with standard dose chemotherapy. Nucleoside analogs such as fludarabine are effective, but even when used as initial therapy, the median duration of remission ranges from only 16 to 24 months. Interferon (IFN) is also active and has been investigated both by incorporating it into the chemotherapy regimen and/or as maintenance therapy, where it may prolong remission. We designed a phase II trial of alternating fludarabine and IFNalpha2a to determine response rate, time to progression and toxicity of this regimen in patients with advanced stage low-grade NHL or mantle cell lymphoma. DESIGN AND METHODS: Patients had received 0-2 prior regimens that did not include nucleoside analogs or IFN and had adequate organ function. Fludarabine was administered intravenously at 25 mg/m2/day for 5 days once every 6 weeks with IFN in weeks 4 and 5 at 3x10(6) U/m2 subcutaneously three times weekly for 6 doses. Treatment continued in responders for 2 cycles past maximal response (minimum 6 cycles). No maintenance was given. RESULTS: Between 1994 and 1999, 31 patients were accrued and were evaluable for toxicity, with 29 eligible for evaluation of response. Toxicity was primarily myelosuppression, with grade 3 neutropenia in 12 patients and grade 4 thrombocytopenia in one patient. The overall response rate was 51.7% (15/29), including 6 complete and 9 partial responses. With a median follow-up of 35.6 months, the median overall survival was 60.8 months, and the median time to disease progression (TTP) was 12.6 months. Of the 15 responding patients, treatment-naive patients had a median response duration of 39.6 months with a median TTP of 42.1 months, while the median response duration was 5.2 months with a median TTP of 14.5 months in patients who had received prior treatment (p=0.0065 and 0.0374, respectively). INTERPRETATION AND CONCLUSIONS: This schedule of alternating fludarabine with IFN does not seem to increase response rate appreciably, but there are some prolonged responses, particularly in previously untreated patients. Given the non-overlapping toxicities of IFN with those of chemotherapy and antibody-based therapeutics, there may be a role for combination therapies, especially if the biological basis of response to IFN can be elucidated.

Adult↗

A nonhydrolyzable reactive cAMP analogue, (S(p))-8-[(4-bromo-2,3-dioxobutyl)thio]adenosine 3',5'-cyclic S-(methyl)monophosphorothioate, irreversibly inactivates human platelet cGMP-inhibited cAMP phosphodiesterase at micromolar concentrations.

We previously showed that 8-[(4-bromo-2,3-dioxobutyl)thio]adenosine 3',5'-cyclic monophosphate inactivates cAMP phosphodiesterase (PDE3A); however, millimolar concentrations were needed to inactivate PDE3A because of ongoing hydrolysis. We have now synthesized a nonhydrolyzable reactive cAMP analogue, (S(p))-8-[(4-bromo-2,3-dioxobutyl)thio]adenosine 3',5'-cyclic S-(methyl)monophosphorothioate (S(p)-8-BDB-TcAMPSMe). S(p)-8-BDB-TcAMPSMe inactivates PDE3A in a time-dependent, irreversible manner, exhibiting saturation kinetics with a k(max) of (19.5 +/- 0.3) x 10(-3) min(-1) and a K(I) of 3.5 +/- 0.3 muM. To ascertain whether S(p)-8-BDB-TcAMPSMe reacts in the active site, nonhydrolyzable analogues of the substrate cAMP, or the competitive inhibitor cGMP, were included to protect against the inactivation of PDE3A. The order of effectiveness of protectants in decreasing the rate of inactivation (with K(d) values in micromolar) is as follows: S(p)-cAMPS (18) > R(p)-cGMPS (560) and S(p)-cGMPS (1260) > 5'-AMP (17 660), R(p)-cAMPS (30 110), and 5'-GMP (42 170). We docked S(p)-8-BDB-TcAMPSMe into PDE3A, based on the structural model of PDE3A-cAMP and the kinetic data from site-directed mutants. The S(p)-8-BDB-TcAMPSMe fits into the active site in the model. These results suggest that inactivation of PDE3A by the affinity reagent is a consequence of reaction at the overlap between cAMP and cGMP binding regions in the active site. S(p)-8-BDB-TcAMPSMe has proven to be an effective active site-directed irreversible cAMP affinity label for platelet PDE3A and can be used to identify amino acids in the active site of PDE3A as well as in other cAMP phosphodiesterases.

3',5'-Cyclic-AMP Phosphodiesterases↗

A new nonhydrolyzable reactive cAMP analog, (Sp)-adenosine-3',5'-cyclic-S-(4-bromo-2,3-dioxobutyl)monophosphorothioate irreversibly inactivates human platelet cGMP-inhibited cAMP phosphodiesterase.

Levels of cAMP that control critical platelet functions are regulated by cGMP-inhibited cAMP phosphodiesterase (PDE3A). We previously showed that millimolar concentrations of the hydrolyzable 8-[(4-bromo-2,3-dioxobutyl)thioadenosine 3',5'-cyclic monophosphate (8-BDB-TcAMP) inactivate PDE3A. We have now synthesized a nonhydrolyzable affinity label to probe the active site of PDE3A. The nonhydrolyzable adenosine 3',5'-cyclic monophosphorothioates, Sp-cAMPS and Rp-cAMPS, function as competitive inhibitors of PDE3A with K(i) = 47.6 and 4400 microM, respectively. We therefore coupled Sp-cAMPS with 1,4-dibromobutanedione to yield (Sp)-adenosine-3',5'-cyclic-S-(4-bromo-2,3-dioxobutyl)monophosphorothioate, [Sp-cAMPS-(BDB)]. Sp-cAMPS-(BDB) inactivates PDE3A in a time-dependent, irreversible reaction with k(max) = 0.0116 min(-1) and K(I) = 10.1 microM. The order of effectiveness of protectants in decreasing the rate of inactivation (with K(d) in microM) is: Sp-cAMPS (24) > Rp-cGMPS (1360), Sp-cGMPS (1460) > GMP (4250), AMP (10600), Rp-cAMPS (22170). These results suggest that the inactivation of PDE3A by Sp-cAMPS-(BDB) is a consequence of reaction at the overlap of the cAMP and cGMP binding regions in the active site.

3',5'-Cyclic-AMP Phosphodiesterases↗

Clinical evolution of the Invisalign appliance.

The Invisalign System of tooth movement has been available to orthodontists since 1999 and has now become available to the entire dental profession. This paper explores the role of this system within the dental armamentarium and describes the clinical evolution of the appliance, based on a feasibility study initiated at the University of the Pacific in 1997.

Adolescent↗