Texas pediatric dentists' attitudes toward practice issues and the role of the component society

A questionnaire addressing practice issues in dentistry and members' expectations of component society activities was sent to members of the Texas Academy of Pediatric Dentistry (N = 269). Response rate was 73%. Respondents were not in full agreement with the American Academy of Pediatric Dentistry recommendation that children first be seen at 12 months, though younger and childless dentists had significantly greater agreement than those who were older and had children. Strong disapproval of proposed independent practice for hygienists was expressed, and strong support was given for assistants to perform coronal polishing and apply sealants. Three-fourths of respondents treat Medicaid patients. In evaluating the role of the component society, respondents--especially women--unanimously affirmed the responsibility of keeping dentists abreast of current information, but also expressed strong support for maintaining relationships with outside groups and representing member views on issues of health care reform. Based on the diffusion theory of communication, a program of proactive public relations is recommended for the first-visit issue.     

Intracellular signaling by reactive oxygen species during hypoxia in cardiomyocytes

Cardiomyocytes suppress contraction and O2 consumption during hypoxia. Cytochrome oxidase undergoes a decrease in Vmax during hypoxia, which could alter mitochondrial redox and increase generation of reactive oxygen species (ROS). We therefore tested whether ROS generated by mitochondria act as second messengers in the signaling pathway linking the detection of O2 with the functional response. Contracting cardiomyocytes were superfused under controlled O2 conditions while fluorescence imaging of 2, 7-dichlorofluorescein (DCF) was used to assess ROS generation. Compared with normoxia (PO2 approximately 107 torr, 15% O2), graded increases in DCF fluorescence were seen during hypoxia, with responses at PO2 = 7 torr > 20 torr > 35 torr. The antioxidants 2-mercaptopropionyl glycine and 1,10-phenanthroline attenuated these increases and abolished the inhibition of contraction. Superfusion of normoxic cells with H2O2 (25 microM) for >60 min mimicked the effects of hypoxia by eliciting decreases in contraction that were reversible after washout of H2O2. To test the role of cytochrome oxidase, sodium azide (0.75-2 microM) was added during normoxia to reduce the Vmax of the enzyme. Azide produced graded increases in ROS signaling, accompanied by graded decreases in contraction that were reversible. These results demonstrate that mitochondria respond to graded hypoxia by increasing the generation of ROS and suggest that cytochrome oxidase may contribute to this O2 sensing.     

Profitability of a university-based clinic using benchmark time lengths for clinical encounters

Reductions in reimbursement are applied to all physicians in a region equally. However, physicians do not practice in equivalent situations. For example, there are few fiscal allowances for academic functions associated with teaching and administration. Furthermore, university-based physicians may practice in clinical venues that cannot be as efficient as nonuniversity sites. Unavoidable inefficiencies may include (1) the costs of maintaining one historical record for a large noncontiguous practice; (2) university-required holiday schedules and sick leave, making university personnel less productive; (3) noncompetitive overhead rates assigned to clinic components by university financial offices; (4) university-based accounting systems that are not designed for effective cost control and the timely generation of useful management information; and (5) poorly managed billing services. Until now, declining reimbursements have generally led to sufficient efficiencies in delivery so that revenues and expenses can be in equilibrium.     

Neither human immunodeficiency virus-1 (HIV-1) nor HIV-2 infects most-primitive human hematopoietic stem cells as assessed in long-term bone marrow cultures

Phenylglyoxylate (benzoylformate) is an intermediate in the anoxic metabolism of phenylalanine and phenylacetate. It is formed by alpha-oxidation of phenylacetyl-CoA. Phenylglyoxylate is oxidatively decarboxylated by phenylglyoxylate-oxidoreductase to benzoyl-CoA, a central intermediate of anaerobic aromatic metabolism. The phenylglyoxylate oxidizing enzyme activity in the denitrifying bacterium Azoarcus evansii was induced during anaerobic growth with phenylalanine, phenylacetate and phenylglyoxylate, but not with benzoate. The new enzyme phenylglyoxylate:acceptor oxidoreductase was purified and studied. The oxygen-sensitive enzyme reduced both NAD+ and viologen dyes. It was composed of five subunits of approximately 50, 48, 43, 24, and 11.5 kDa; the native mass as determined by gel filtration was 370 kDa, suggesting an alpha2 beta2 gamma2 delta2 epsilon2 composition. Phenylglyoxylate:acceptor oxidoreductase exhibited an ultraviolet/visible spectrum characteristic for an iron-sulfur protein and contained 35 +/- 4 mol Fe, 36 +/- 4 mol acid-labile sulfur, and 1.1 +/- 0.2 mol FAD/mol. The enzyme was specific for phenylglyoxylate (Km 45 microM) and coenzyme A (Km 55 microM); 2-oxoisovalerate was oxidized with 15% of the rate. The turnover number with benzyl viologen at 37 degrees C was 46 s(-1) at the optimal pH of 8. The enzyme catalyzed a NAD(P)H:viologen dye transhydrogenation reaction, NAD(H) being the preferred coenzyme. It also catalyzed an isotope exchange between CO2 and the carboxyl group of the substrate. The data are consistent with the following hypothesis. The enzyme complex consists of a core enzyme of four subunits with the composition alpha2 beta2 gamma2 delta2, as reported for archaeal 2-oxoacid:ferredoxin oxidoreductases; this complex is able to reduce viologen dyes. The holoenzyme contains in addition an epsilon2 unit that catalyzes the transfer of electrons from a small ferredoxin-like subunit of the core complex to NAD+; this unit also catalyzes the transhydrogenase reaction, carries FAD and resembles ferredoxin:NAD(P)+-oxidoreductase.     

Autoimmunity and its treatment in aplastic anemia

A pilot survey of men aged 35 and over in Buenos Aires indicated that many had one or more risk factors for chronic diseases. A low response rate hampered the investigation: on average it proved necessary to visit several homes in order to obtain one interview. Furthermore, at the cost of US$ 10 incurred per interview, large prospective investigations would be precluded in most developing countries, but case-control studies assessing tobacco use and other risk factors retrospectively would be a good alternative.     

Operating on placental support: the ex utero intrapartum treatment procedure

While treating eight fetuses with predictable airway obstruction, the authors developed a systematic approach, the ex utero intrapartum treatment procedure, to secure the airway during delivery. Six patients had their trachea plugged or clipped in utero for treatment of congenital diaphragmatic hernia, and two patients had prenatally diagnosed cystic hygroma of the neck and oropharynx. The ex utero intrapartum treatment procedure was performed by using high doses of inhaled halogenated agents to facilitate uterine relaxation during cesarean section, securing the fetal airway while feto-placental circulation remained intact, and then dividing the umbilical cord. A variety of procedures were performed during the ex utero intrapartum treatment procedure including bronchoscopy, orotracheal intubation, tracheostomy, tracheostomy with retrograde orotracheal intubation, tracheoplasty, removal of internal tracheal plug, removal of external tracheal clip, central line placement, and instillation of surfactant. There were minimal maternal or fetal complications during the procedure. This approach requires the coordinated efforts of pediatric surgeons, obstetricians, anesthesiologists, sonographers, and neonatologists. The combination of intensive maternal-fetal monitoring, cesarean section with maximal uterine relaxation, and maintenance of intact feto-placental circulation provides a controlled environment for securing the airway in babies with prenatally diagnosed airway obstruction.