Medical Clearance for Common Dental Procedures

Medical consultations before dental procedures present opportunities to integrate cross-disciplinary preventive care and improve patient health. This article presents recommendations related to patients with certain medical conditions who are planning to undergo common dental procedures, such as cleanings, extractions, restorations, endodontic procedures, abscess drainage, and mucosal biopsies. Specifically, prophylactic antibiotics are not recommended for preventing prosthetic joint infections or infectious endocarditis except in certain circumstances. Anticoagulation and antiplatelet therapies typically should not be suspended for common dental treatments. Elective dental care should be avoided for six weeks after myocardial infarction or bare-metal stent placement or for six months after drug-eluting stent placement. It is important that any history of antiresorptive or antiangiogenic therapies be communicated to the dentist. Ascites is not an indication for initiating prophylactic antibiotics before dental treatment, and acetaminophen is the analgesic of choice for patients with liver dysfunction or cirrhosis who abstain from alcohol. Nephrotoxic medications should be avoided in patients with chronic kidney disease, and the consultation should include the patient's glomerular filtration rate. Although patients undergoing chemotherapy may receive routine dental care, it should be postponed when possible in those currently undergoing head and neck radiation therapy. A detailed history of head and neck radiation therapy should be provided to the dentist. Multimodal, nonnarcotic analgesia is recommended for managing acute dental pain.

Coccidioidomycosis (Valley Fever) in Primary Care

Primary pulmonary coccidioidomycosis (valley fever) is caused by inhaling airborne spores of the fungus Coccidioides immitis or Coccidioides posadasii. Residing in or traveling to areas endemic for Coccidioides is required for the diagnosis; no person-to-person or zoonotic contagion occurs. The incidence of coccidioidomycosis is increasing in endemic areas, and it has been identified as the cause of as many as 17% to 29% of all cases of community-acquired pneumonia in some regions. Obtaining a travel history is recommended when evaluating patients with community-acquired pneumonia. Diagnosis usually relies on enzyme immunoassay with immunodiffusion confirmation, but these tests may not be positive for one to three weeks after disease onset. Antifungal agents are not recommended for treatment unless the patient is at risk of or shows signs of complicated or disseminated infection. When antifungals are used, fluconazole and itraconazole are most commonly recommended, except during pregnancy. Treatment may continue for as long as three to 12 months, although lifetime treatment is indicated for patients with coccidioidal meningitis. Monitoring of complement fixation titers and chest radiography is recommended until patients stabilize and symptoms resolve. In patients who are treated with antifungals, complement fixation titers should be followed for at least two years.

Crystallization and preliminary X-ray analysis of electron transfer flavoproteins from human and Paracoccus denitrificans

Mammalian electron transfer flavoprotein (ETF) is a soluble, heterodimeric flavoprotein responsible for the oxidation of at least nine primary matrix flavoprotein dehydrogenases. Crystals have been obtained for the recombinant human electron transfer flavoprotein (ETFhum) by the sitting-drop vapor diffusion technique using polyethylene glycol (PEG) 1500 at pH 7.0 as the precipitating agent. ETFhum crystallizes in the monoclinic space group P2(1), with unit cell parameters a = 47.46 angstrum, b = 104.10 angstrum, c = 63.79 angstrum, and beta = 110.02 degrees. Based on the assumption of one alpha beta dimer per asymmetric unit, the Vm value is 2.69 angstrum 3/Da. A native data set has been collected to 2.1 angstrum resolution. One heavy-atom derivative has also been obtained by soaking a preformed crystal of ETFhum in 2 mM thimerosal solution for 2h at 19 degrees C. Patterson analysis indicates one major site. The analogous electron transfer flavoprotein from Paracoccus denitrificans (ETFpar) has also been crystallized using PEG 8000 at pH 5.5 as the precipitating agent. ETFpar crystallizes in the orthorhombic space group P2(1)2(1)2(1), with unit cell parameters a = 79.98 angstrum, b = 182.90 angstrum, and c = 70.07 angstrum. The Vm value of 2.33 angstrum 3/Da is consistent with two alpha beta dimers per asymmetric unit. A native data set has been collected to 2.5 angstrum resolution.

Expression and characterization of human and chimeric human-Paracoccus denitrificans electron transfer flavoproteins

Electron transfer flavoprotein (ETF) is a heterodimer that contains a single equivalent of FAD and accepts electrons from nine flavoprotein dehydrogenases in the mitochondrial matrix. Human ETF was expressed in Escherichia coli using the expression vector previously employed to express Paracoccus denitrificans ETF (Bedzyk, L. A., Escudero, K. W., Gill, R. E., Griffin, K. J., and Frerman, F. E. (1993) J. Biol. Chem. 268, 20211-20217). cDNAs encoding the beta and alpha subunits of the human protein were inserted into the vector, mimicking the arrangement of the P. denitrificans genes in which coding sequences are joined by overlapping termination and initiation codons. A human ETF containing 30% P. denitrificans sequence at the amino terminus of the beta subunit was also expressed and purified. This chimeric ETF has 64% sequence identity with the human sequence in the substituted region. Kinetic constants of medium chain and short chain acyl-CoA dehydrogenases for the chimeric ETFs were slightly changed from those of human ETF; but, there are marked differences in the kinetic constants of sarcosine dehydrogenase and electron transfer flavoprotein-ubiquinone oxidoreductase with the two ETFs. Absorption spectra of the three redox states of human, chimeric, and P. denitrificans ETF flavins are identical. However, the flavin circular dichroism spectra of the three ETFs are characteristic for each species. The spectrum of the chimeric ETF has both human and P. denitrificans ETF features. The amplitude of the 436 nm band is identical to that of the of the human ETF flavin, but the amplitude of the 375 nm band is identical to that of the P. denitrificans ETF flavin. Thus, flavin in the chimeric ETF appears to be exposed to dipoles in the protein framework provided by human and bacterial sequences. These spectral data indicate that the flavin is located in the vicinity of the amino-terminal region of the beta subunit. The kinetic data suggest that the amino-terminal region of the beta subunit comprises part of the docking site for some primary dehydrogenases and electron transfer flavoprotein-ubiquinone oxidoreductase.

Regulation of the rat muscle glycogen phosphorylase-encoding gene during muscle cell development

The muscle isozyme of glycogen phosphorylase (MGP) catalyzes the hydrolysis hydrolysis of intracellular glycogen in mammalian tissues and is produced in skeletal muscle, brain and heart. The MGP gene is developmentally and neutrally regulated in skeletal muscle, but little is known about the gene's transcriptional regulation. We have isolated and characterized the 5' flanking region of rat MGP. Truncated portions of the MGP 5' flanking region were coupled to the bacterial cat reporter gene and used in transient transfection assays in the mouse muscle C2C12 cell line. The region between -211 and +62 contained the smallest regulatory domain capable of demonstrating developmentally regulated myogenic expression in C2C12 cells. This was in contrast with findings from another investigation that transfected this cell line with human MGP [Lockyer and McCracken, J. Biol. Chem. 266 (1991) 20262-20269]. A 172-nucleotide (nt) region between -839 and -666 functioned as a potent enhancer in C2C12 cells when coupled to its cognate promoter, but not when coupled to a simian virus 40 promoter. This rat MGP enhancer region is 78% identical to a comparable region of the human MGP 5' flanking region, but contains only one putative regulatory element that has been previously identified in other muscle genes. These data suggest that rat MGP transcription in C2C12 muscle cells is modulated by a potent enhancer that utilizes novel regulatory elements.

Characterization of the 5' flanking region of the gene encoding rat liver glycogen phosphorylase

A genomic region encompassing 800 bp of the promoter-regulatory region and exon 1 of the gene (LGP) encoding rat liver glycogen phosphorylase has been isolated and characterized. Transcripts of the LGP gene initiate predominantly within an 8-bp region 48-bp upstream from the start codon. Additional transcripts were detected that initiate as far as 95 bp upstream from the start codon. To identify cis-acting sequences involved in regulating transcription, HepG2 cells were transfected with vectors containing serial deletions of the promoter-regulatory region of LGP ligated to the cat reporter gene. Two upstream regions were found to enhance transcription. One of these regions contains an alternating purine-pyrimidine sequence. LGP, which lacks a consensus TATA sequence, is like TATA-less and CAAT-less housekeeping genes in that it contains G + C-rich domains upstream from multiple transcription start points. Nuclear proteins from adult rat tissues bound in a tissue-specific fashion to one of these G + C-rich regions.

Polymerase chain reaction for detection of Mycoplasma gallisepticum

A species-specific 760-base pair (bp) BamHI to EcoRI DNA fragment (fMG-2) was isolated from a Mycoplasma gallisepticum (MG) genomic library constructed in plasmid pUC8. Based on the DNA sequence data of fMG-2, a pair of 25 base primers, designated amplification (Amp) left (L) and right (R) primers, was synthesized. When used in the polymerase chain reaction (PCR), the Amp L and R primers directed amplification of DNA of 16 MG strains yielding an expected 732-bp product, but did not amplify DNA of Escherichia coli, calf thymus, lambda phage, pUC8 plasmid, or 16 other species of avian mycoplasmas. As low as 10(-6) picogram of MG DNA, a fraction of the total chromosomal content of one cell, was detected following amplification by PCR. PCR amplification products were visualized by either ethidium bromide/ultraviolet exposure or hybridization with a 481-bp probe (fMG-3) prepared from the central region of fMG-2.