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Biomedical subjects

T Head

Publications and source records attributed to T Head.

8 recordsLinked to original sources
PubMed2001

A multi-centre study of Osseotite implants supporting mandibular restorations: a 3-year report.

This multi-centre study evaluated the performance of the Osseotite implant in the mandibular arch. Osseotite implants (n = 688) were placed in 172 patients; 43.5% were placed in the anterior mandible and 66.5% in the posterior mandible. Fifteen per cent of the implants were placed in soft bone, 56.9% in normal bone and 28.1% in dense bone. During placement, 49.9% of the implants were identified as having a tight fit, 48.6% a firm fit and 1.5% a loose fit. About one-third of the implants (32.4%) were short (10 mm in length or less). After 36 months, only 5 implants had been lost, for a cumulative survival rate of 99.3%. The 3-year results of this study indicate a high degree of predictability with placement of Osseotite implants in the mandibular arch.

Alveolar Bone Loss↗
PubMed2000

Computing with DNA by operating on plasmids.

A new method of computing using DNA plasmids is introduced and the potential advantages are listed. The new method is illustrated by reporting a laboratory computation of an instance of the NP-complete algorithmic problem of computing the cardinal number of a maximal independent subset of the vertex set of a graph. A circular DNA plasmid, specifically designed for this method of molecular computing, was constructed. This computational plasmid contains a specially inserted series of DNA sequence segments, each of which is bordered by a characteristic pair of restriction enzyme sites. For the computation reported here, the DNA sequence segments of this series were used to represent the vertices of the graph being investigated. By applying a scheme of enzymatic treatments to the computational plasmids, modified plasmids were generated from which the solution of the computational problem was selected. This new method of computing is applicable to a wide variety of algorithmic problems. Further computations in this style are in progress.

Computing Methodologies↗
PubMed1999

Energy substrate metabolism during dual work rate exercise: effects of order.

Changes in workload are evident during many physical activities. The aim of this study was to assess total substrate metabolism when the temporal placement of a period of higher-intensity work (75% VO2max) was varied within a low-intensity exercise session (50% VO2max). One experimental trial (higher intensity first) comprised 5 min low-intensity work, followed by 15 min high-intensity work, followed by 40 min low-intensity work. The other trial (low intensity first) comprised 40 min low-intensity work, followed by 15 min high-intensity work, followed by 5 min low-intensity work. The trials were designed to achieve an identical total energy expenditure. Energy expenditure, fat and carbohydrate utilization were estimated by expired gas analysis and compared between conditions. Mean total energy expenditure during the higher-intensity phase was 1076 kJ and 1128 kJ in the high-intensity first and low-intensity first trials respectively (t6 = -3.76, P = 0.0047). Mean total energy expenditure for the whole trial was 3356 kJ and 3452 kJ in the high-intensity first and low-intensity first trials respectively (t6 = -3.48, P = 0.0065). Mean whole-trial fat utilization was 1753 kJ and 1857 kJ in the high-intensity first and low-intensity first trials respectively (t6 = -0.76, P = 0.24). Our findings suggest that changing the temporal placement of higher-intensity work within a low-intensity exercise session has a significant effect on total energy expenditure but not on the rate of fat oxidation.

Adult↗
PubMed1995

Peroneal nerve repetitive nerve stimulation test: its value in diagnosis of myasthenia gravis and Lambert-Eaton myasthenic syndrome.

We have developed a repetitive nerve stimulation (RNS) technique for the peroneal nerve. Normal limits for the decremental responses for the anterior tibialis and extensor digitorum brevis muscles are 6-21% at the low rate of stimulation and 44-70% at the high rate of stimulation. These values exceed the normal limits for other commonly tested muscles. This may be due to the lower safety factor for neuromuscular transmission for the anterior tibialis and extensor digitorum brevis muscles. We present 4 cases in which the peroneal nerve RNS test was crucial for the diagnosis of the limb-girdle form of MG or LEMS. Thus, we conclude that, in a small number of patients with neuromuscular transmission disorders, the peroneal nerve RNS test is needed for confirmation of disease.

Adult↗
PubMed1994

Shifting the responsibility for payment for state hospital services to community mental health agencies.

OBJECTIVE: In 1990 the state of Arkansas shifted financial responsibility for state hospital services to community mental health centers; through a policy known as "bed buy-back," centers now authorize all state hospital admissions and prospectively purchase bed days for their patients. Characteristics of patients hospitalized before and after implementation of the policy were examined to determine how the policy affected hospital admission rates, types of patients admitted, and the amount of contact between CMHC and hospital staff about admitted patients, as well as how these elements were affected differently in rural and urban areas. METHODS: Changes in the types of patients admitted over the 13 months before and 14 months after the change in financing were studied through retrospective chart review of 648 patients. Administrative data were used to examine changes in numbers of admissions for 30 months before and 26 months afterward. Data were analyzed by piecewise regression, least-squares, and logistic regression analyses. RESULTS: After financial decentralization, state hospital use was reduced in both urban and rural areas, although the reduction in urban areas was proportionally greater. Contrary to expectation, admissions were not limited to the most severely ill, disruptive, or substance-abusing patients, nor were they more likely to be readmitted. For patients who were admitted, communication between the community and the state hospital was greater than before financial decentralization. CONCLUSIONS: Shifting financial responsibility for patient care significantly reduced state hospital use, did not affect patient mix, and apparently increased coordination of care between community and hospital. Whether bed buy-back has affected the kind or quality of services delivered in the community awaits further study.

Adolescent↗
PubMed1991

Aneurysmal bone cyst of the mandible.

The aneurysmal bone cyst (ABC) is a benign, solitary lesion of bone which is most commonly found in the long bones and vertebral column. Its occurrence in the mandible is uncommon. Because of its infrequent appearance, the ABC may be mistaken for neoplastic lesions. In the past, management has consisted of curettage, cryotherapy and local resection. In this publication we present a case of ABC of the mandible. We include a review of the literature, a discussion of the etiology, pathogenesis and management of this interesting lesion.

Adolescent↗
PubMedDate not supplied

A new external approach to the pterygomaxillary fossa and parapharyngeal space.

A new direct approach to the area of the pterygomaxillary fossa and the parapharyngeal space is described. This procedure was developed because previously described methods either offered limited access to the area or resulted in significant functional defects. The approach described here results in a wide-field exposure of both the pterygomaxillary and parapharyngeal spaces with no sacrifice of either mandibular function or the sensory supply of the face or oral cavity. The parapharyngeal space is entered through a transcervical incision. This, combined with double osteotomies of the mandible, allows the ascending ramus with its intact neurovascular bundle to be reflected laterally and superiorly, along with the attached masseter muscle and the overlying skin. The result is an excellent exposure of the pterygomaxillary fossa and the base of skull. Following removal of the tumor, the ramus of the mandible is replaced and fixed with interosseous wiring and the application of arch bars, thus restoring normal dental occlusion. The technique described here was worked out on cadaveric dissection before being applied to a clinical case.

Adolescent↗