Diagnosing and comanaging patients with obstructive sleep apnea syndrome.

BACKGROUND: Obstructive sleep apnea syndrome, or OSAS, is a common, but underdiagnosed, disorder that potentially is fatal. It is characterized by repetitive episodes of complete or partial upper airway obstruction leading to absent or diminished airflow into the lungs. These episodes usually last 10 to 30 seconds and result in loud snoring, a decrease in oxygen saturation, and chronic daytime sleepiness and fatigue. The obstruction is caused by the soft palate, base of the tongue or both collapsing against the pharyngeal walls because of decreased muscle tone during sleep. Potentially fatal systemic illnesses frequently associated with this disorder include hypertension, pulmonary hypertension, heart failure, nocturnal cardiac dysrhythmias, myocardial infarction and ischemic stroke. CLINICAL IMPLICATIONS: The classic signs and symptoms of OSAS may be recognizable by dental practitioners. Common findings in the medical history include daytime sleepiness, snoring, hypertension and type 2 diabetes mellitus. Common clinical findings include obesity; a thick neck; excessive fat deposition in the palate, tongue (enlarged) and pharynx; a long soft palate; a retrognathic mandible; and calcified carotid artery atheromas on panoramic and lateral cephalometric radiographs. CONCLUSIONS: Dentists cognizant of these signs and symptoms have an opportunity to diagnose patients with occult OSAS. After confirmation of the diagnosis by a physician, dentists can participate in management of the disorder by fabricating mandibular advancement appliances and performing surgical procedures that prevent recurrent airway obstruction.

Treatment and prevention of alveolar fractures and related injuries.

Dentoalveolar trauma does not pose a significant morbid risk for the trauma patient. However, the long-term consequences of mismanagement can be devastating. Early, correct diagnosis, and appropriate referral of these injuries can affect the success of treatment. Failure to recognize or obtain appropriate consultation can result in premature tooth or alveolar bone loss, resulting in problematic prosthetic rehabilitation. The purpose of this article is to review the concepts of recognition, management, and prevention of dentoalveolar trauma. In situations where the possibility of trauma is likely, such as in athletics, dentoalveolar and related fractures can be prevented through the use of mouthguards fabricated by health care professionals.

Defining the boundaries of zebrafish developmental genetics.

The first systematic, functional screens to identify the genes involved in vertebrate embryogenesis have been completed in the zebrafish, Danio rerio. In an extraordinary issue of the journal Development, devoted entirely to the results of these screens, over 500 mutant loci, many with multiple alleles, are described and classified according to the phenotypes they produce. Each class defines a small number of genes that act together to determine the proper development of many features of vertebrate anatomy, from the determination of body plan to the development of discrete organs and cell types.

Positional signaling by hedgehog in Drosophila imaginal disc development.

We describe a dominant gain-of-function allele of the segment polarity gene hedgehog. This mutation causes ectopic expression of hedgehog mRNA in the anterior compartment of wing discs, leading to overgrowth of tissue in the anterior of the wing and partial duplication of distal wing structures. The posterior compartment of the wing is unaffected. Other imaginal derivatives are affected, resulting in duplications of legs and antennae and malformations of eyes. In mutant imaginal wing discs, expression of the decapentaplegic gene, which is implicated in the hedgehog signaling pathway, is also perturbed. The results suggest that hedgehog protein acts in the wing as a signal to instruct neighboring cells to adopt fates appropriate to the region of the wing just anterior to the compartmental boundary.

The fub-1 mutation blocks initial myofibril formation in zebrafish muscle pioneer cells.

The earliest muscle in zebrafish arises from iterated sets of two to six cells in each somite, the muscle pioneers (MP). MP develop synchronously in young trunk myotomes adjacent to the notochord, precisely where the horizontal myoseptum will form. They elongate without cell fusion and differentiate hours earlier than surrounding cells, thus providing a simple and accessible system for in vivo study of myogenesis and muscle patterning. Before the MP form definitive myofibrils they assemble long bundles of actin-containing filaments, similar to "stress-fiber-like structures" reported by others. In fub-1 mutants, in which myofibrils are disorganized in all skeletal muscle cells, the MP appear and elongate normally, but ordered actin filament bundles are not seen. This defect could underlie the later myofibrillar ones, consistent with the proposal that actin filament bundles are essential for proper formation of the muscle contractile apparatus.

Mutations affecting skeletal muscle myofibril structure in the zebrafish.

We describe embryonic lethal mutations in the zebrafish, Brachydanio rerio, which affect organization of skeletal muscle myofibrils. The mutations, fub-1(b45) and fub-1(b126), were independently isolated from progeny of gamma-irradiated females. Each segregates as a single recessive gene: b45 is located about 23 map units from its centromere. The b126 mutation has a similar but slightly larger apparent gene-centromere distance and a less severe phenotype. The two mutations fail to complement, suggesting that they are allelic. Homozygous b45 mutant embryos are paralyzed, and their axial skeletal muscle cells are unstriated, containing severely disorganized myofibrillar components. Gel-electrophoretic comparisons of b45 mutant and wild-type muscle proteins failed to reveal absent or altered major myofibrillar proteins. Embryos genetically mosaic for b45 were also phenotypically mosaic, suggesting that the defect is cell-autonomous. We suggest that these mutations identify a gene required for proper organization of skeletal muscle myofibrils, and that the more severe mutation may represent a null allele.