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Biomedical subjects

B Grayson

Publications and source records attributed to B Grayson.

17 recordsLinked to original sources
PubMed2003

Correlation of hyperforin content of Hypericum perforatum (St John's Wort) extracts with their effects on alcohol drinking in C57BL/6J mice: a preliminary study.

Extracts of the herb St John's Wort have been shown to reduce alcohol intake in alcohol-preferring rats, but it is not known which of the constituent(s) are responsible for this effect. In this study, the effect of a crude methanolic extract of Hypericum perforatum (negligible hyperforin content) on alcohol drinking in C57BL/6J alcohol-preferring mice was compared with that of a hyperforin-rich extract (45% hyperforin) prepared by extracting the herb with supercritical carbon dioxide. The dose of the hyperforin-rich extract required to significantly reduce 10% ethanol intake (5 mg/kg) was 125-fold less than that required for the crude extract (625 mg/kg), and was comparable to the dose of fluoxetine (10 mg/kg) required to produce a similar effect. None of these agents significantly affected water intake. These results suggest that the effects of H. perforatum extracts on alcohol drinking behaviour are due to the hyperforin content of the herb rather than to other, more polar constituents. Hyperforin is an unstable compound and this study also highlights the effect of different methods of extract preparation on hyperforin content.

Alcohol Deterrents↗
PubMed1999

Mandibular growth after distraction in patients under 48 months of age.

Distraction osteogenesis is an effective technique for reconstruction of the congenitally deficient mandible. However, the age at which it is best performed remains under discussion. Distraction performed at an early age, while possibly allowing the face to develop with a more normal functional matrix, may entail a higher rate of complications. Additionally, it is possible that subsequent asymmetric growth of the mandible may necessitate serial distraction. To address this issue, the clinical records and cephalometric radiographs of all patients less than 48 months of age undergoing mandibular distraction at New York University Medical Center between August of 1989 and August of 1997 were examined. There was a total of 14 patients ranging in age from 19 months to 43 months. Nine patients had a diagnosis of unilateral craniofacial microsomia, three had Treacher Collins syndrome, one had Nager syndrome, and one had bilateral developmental micrognathia. The average amount of distraction was 27 mm (range, 23 to 39 mm) in unilateral cases and 24 mm in bilateral cases (range, 15 to 31 mm). The period of clinical follow-up averaged 32.6 months (range, 12 to 92 months). All patients showed significant improvement in craniofacial appearance, and in four patients, long-term tracheostomy tubes were removed. There were two major complications. In one patient with craniofacial microsomia, there was a relapse in the early postretention phase related to the presence of a dentigerous cyst. This required removal of the cyst and repeat distraction. In the patient with Nager syndrome, a coronoid ankylosis developed requiring surgical release. There were no other major complications. The scars required revision in only two of the patients. Cephalometric analysis of the patients in the study revealed a differential in the rate of growth between the affected and the unaffected side in all cases of craniofacial microsomia. The affected side always grew at a slower rate than the contralateral side after the distraction process was complete. This led to a progressive asymmetry of the rami, clinically expressed by some degree of facial asymmetry and an occlusal cant. For this reason, secondary distraction was required in one patient and is planned in a second. Initial overcorrection of the patient would seem to minimize the likelihood that secondary distraction will be necessary. Distraction osteogenesis for reconstruction of the mandible in this subset of young patients was a safe and effective technique for improving the craniofacial skeletal form and appearance, with minimal associated morbidity. Longer follow-up is necessary to assess the full impact of growth in these cases.

Child, Preschool↗
PubMed1998

Presurgical columellar elongation and primary retrograde nasal reconstruction in one-stage bilateral cleft lip and nose repair.

We present a new combined approach to primary bilateral cleft lip, nose, and alveolus repair using presurgical nasoalveolar molding combined with a one-stage lip, nose, and alveolus repair. Presurgical alveolar molding is used to bring the protruding premaxilla back into proper alignment with the lateral segments in the maxillary arch. Presurgical nasal molding produces tissue expansion of the short columella and nasal lining. A coordinated surgical approach involves a one-stage repair of the lip, nose, and alveolus. The nasal repair uses a retrograde approach in which the prolabial flap and columella are reflected over the nasal dorsum by continuing the dissection behind the prolabium up the membranous septum and over the septal angle. Tissues are dissected out from between the tip cartilages, and the domes are sutured together in the midline. This method joins a new class of bilateral cleft repairs that place the primary emphasis on correction of the deformity of the nasal tip cartilages.

Alveolar Process↗
PubMed1998

A virtual reality system for bone fragment positioning in multisegment craniofacial surgical procedures.

This article reports our clinical experience since 1994 with rigid-motion tracking of bone fragments during craniofacial surgical procedures, using a virtual reality approach. Three noncollinear infrared diodes are fixed to the skull base. A pointer is used to register anatomic features on the patient to those on the computerized tomography-based model of the patient within a computer work station. Three diodes are then attached to each fragment just before the osteotomy is completed. Rigid motions of the fragment are thus tracked and reported to the surgeon by using virtual reality techniques. Errors in fragment positioning are reported both graphically and numerically with respect to a precomputed optimum fragment position. This guidance system allows multisegment midface osteotomies to be performed more precisely. The main problems encountered so far have been devascularization-infection and difficulties in maintaining correct position during application of rigid fixation. Devascularization-infection problems have been addressed by minimizing surgical exposure of the bone. Soft-fixation plates and temporary Kirschner wire fixation have helped with intermediate positioning, but an intraoperative mechanical positioning device would be useful in the future.

Adolescent↗
PubMed1993

The prolabial unwinding flap method for one-stage repair of bilateral cleft lip, nose, and alveolus.

This paper describes a one-stage reconstruction of the complete bilateral cleft lip, nose, and alveolus using an asymmetrically designed prolabial flap. The columella of the nose and the central lip are produced by "unwinding" the columellar and labial sections of the prolabium around a small central tab, which is used to center the junction between the lip and columella. Only two scars are produced, both of which run vertically along each philtral column. Accurate preoperative orthopedics without lip adhesion is considered essential to this repair. The principal advantage/disadvantage to the method is its asymmetrical design. If asymmetries result, they have been easily corrected. Eight consecutive cases are presented with follow-up ranging from 1.5 to 6.3 years.

Alveolar Process↗
PubMed1991

Landmarks in three dimensions: reconstruction from cephalograms versus direct observation.

A method for generating three-dimensional landmark locations from routine biplane pairs of cephalograms was previously introduced. In this article we compare the locations thus reconstructed to the same configurations as directly recorded through a redundant network of interpoint distances measured with calipers. Six mandibular landmarks were located by both methods on each of 10 dry skulls. With the caliper distances is associated a standard error that can be estimated without explicit remeasurement by the method of "adjustment of networks" familiar from surveying. These standard errors are consistent with the remeasurement error both of the caliper measurements and of the stereolocation from cephalograms; the methods appear to have the same precision, about 0.4 mm per distance. The bias (systematic shift) of the biplane reconstructions with respect to the points used for laying down the calipers may be estimated by regressions of distance discrepancies on the direction cosines of the separations between pairs of landmarks. The caliper tips placed condylion approximately 10 mm medially and a bit forward of where we chose to reconstruct it from biplane cephalograms. The caliper locations of gonion average about 1.6 mm back of their cephalometric position, while those at menton and lower incisal edge are forward by some 1.4 mm. We conclude that the biplane reconstruction (the "three-dimensional cephalogram") is sufficiently accurate for routine clinical and surgical application.

Analysis of Variance↗
PubMed1988

The three-dimensional cephalogram: theory, technique, and clinical application.

The Broadbent-Bolton cephalostat produces intrinsically three-dimensional information about cranial form. Yet in the clinical setting, this information has been used primarily two dimensions at a time in the separate study of lateral or posteroanterior cephalograms. In this article we demonstrate an expedient use of existing cephalostat-based data sets to derive certain analyses of three-dimensional form. The technique is essentially the same as that of the Broadbent-Bolton "Orientator," an exploitation of the geometry of the cephalostat to simulate stereophotogrammetry. The three-dimensional method supports the usual biometrics of landmark locations, and takes advantage of a normative data base that is suited for semiautomatic analysis of syndromic data. The principal drawback of the method is its inability to represent curving form in three dimensions. However, in comparison with computed tomography (CT), it involves low radiation dose, is simpler to obtain, has an available normative data base, and is more practical for quantitative or long-term serial analysis.

Biometry↗
PubMed1986

Three-dimensional computer-assisted design of craniofacial surgical procedures: optimization and interaction with cephalometric and CT-based models.

A computer program is described which aids the clinician in planning craniofacial surgical procedures. It operates on a three-dimensional landmark data base derived by combining posteroanterior and lateral cephalograms from the patient and from the Bolton normative standards. A three-dimensional surgical simulation program based on computerized tomographic (CT) data is also described which can be linked to the cephalometrically based program. After the clinician has selected the number and type of osteotomies to be performed on the patient, an automated optimization program computes the postoperative positions of these fragments which best fit the appropriate normal cephalometric form. The clinician then interactively modifies the design to account for such variables as bone-graft resorption, relapse tendency, occlusal disparities, and the condition of the overlying soft-tissue matrix. Osteotomy movement specifications are easily transferred between the CT-based and the cephalometrically based surgical simulation programs. This allows the automated positioning step to be performed on the cephalometrically based model while the interactive step is performed using the superior image provided by the CT-based model.

Cephalometry↗
PubMed1984

Early surgery for craniofacial synostosis: an 8-year experience.

A prospective review is presented of 50 patients with one of the craniofacial synostosis syndromes who underwent early interventive craniofacial surgical correction (average age 7.6 months at time of surgery). The study has demonstrated the efficacy and safety of the techniques when employed in the infant. Satisfactory cranio-orbital form was achieved in the majority of the patients, although 10 patients required secondary surgery because of sutural refusion or the development of turricephaly or calvarial contour irregularities. Despite earlier hopes, this surgery did not result in the development of satisfactory occlusal relationships and midfacial form in the craniofacial dysostosis group (Crouzon's, Apert's, etc.). Based on this clinical experience, a surgical treatment plan is presented for the newborn with craniofacial synostosis.

Acrocephalosyndactylia↗
PubMed1984

Le Fort III advancement osteotomy in the growing child.

A prospective clinical and cephalometric study was conducted on 12 patients under the age of 12 years undergoing Le Fort III advancement with the following findings: 1. There was a remarkable degree of postoperative skeletal stability of the midfacial segment. 2. Disharmony in jaw relationship (anterior crossbite) observed during the period of longitudinal postoperative study could be attributed to expected mandibular development. 3. In some patients, growth and development of the maxilla in a forward and downward direction were documented after Le Fort III advancement. The authors recommend that a Le Fort III advancement can be safely performed at approximately age 4 without a deleterious effect on midfacial development in the patient with craniofacial dysostosis.

Cephalometry↗
PubMed1981

Cephalometric analysis: part I.

A protocol for cephalometric analysis is presented to enable the clinician to evaluate the bony face by subdividing it into four components: 1. Vertical facial measurements 2. Horizontal midface measurements 3. Horizontal lower face measurements 4. Dental measurements. The clinician is encouraged to view the components alone and together. Caution is advised in deriving the treatment plans solely from the cephalometric analysis. Emphasis is placed on integrating the data derived from the cephalometric analysis with the clinical picture, history, dental model analysis, soft-tissue analysis, and patient desires.

Cephalometry↗