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Biomedical subjects

B R Carlson

Publications and source records attributed to B R Carlson.

At least 19 recordsLinked to original sources
PubMed1998

Overview and initial results of the very long baseline interferometry space observatory programme

High angular resolution images of extragalactic radio sources are being made with the Highly Advanced Laboratory for Communications and Astronomy (HALCA) satellite and ground-based radio telescopes as part of the Very Long Baseline Interferometry (VLBI) Space Observatory Programme (VSOP). VSOP observations at 1.6 and 5 gigahertz of the milli-arc-second-scale structure of radio quasars enable the quasar core size and the corresponding brightness temperature to be determined, and they enable the motions of jet components that are close to the core to be studied. Here, VSOP images of the gamma-ray source 1156+295, the quasar 1548+056, the ultraluminous quasar 0014+813, and the superluminal quasar 0212+735 are presented and discussed.

Journal Article↗
PubMed1996

Long-term observations of extensive fixed partial dentures on mandibular canine teeth.

Twelve patients were followed for 15 years after treatment with a 12-unit cantilever fixed partial denture on the mandibular canines opposite to a complete maxillary denture. Four constructions failed and had to be removed but four were still in function after 15 years. Four patients died during the observation period still wearing their constructions. Endodontic complications, pulpal necrosis and loss of retention of posts were the most frequent, while caries and periodontal lesions were rare. The maintenance costs over the years were fairly low even compared to maintenance costs for patients treated with implants. Extensive mandibular cantilever fixed partial dentures may be used in the rehabilitation of patients with a very reduced dentition and a history of difficulties adapting to removable dentures.

Adult↗
PubMed1994

Physique and motor performance characteristics of US national rugby players.

Anthropometric and performance data were collected on 65 US rugby players (mean age = 26.3 years) to make comparison on these characteristics by player position and performance level. Anthropometry included stature, body mass, nine skinfolds, two girths and two bone breadths. Skinfold patterns, estimated percent fat and Heath-Carter somatotypes were calculated from anthropometry. Motor performance measures included standing vertical jump, 40 yard dash, 110 yard dash, shuttle run, repeated jump in place, push-up, sit-up and squat thrust. Descriptive statistics were used for the total sample as well as selected sub-groups. Discriminant function analyses were employed to determine which combination of variables best discriminated between position and level of performance for the anthropometric and performance data. The results indicated that forwards were taller, heavier and had more subcutaneous adiposity than backs. Additionally, forwards and backs differed in somatotypes, with forwards being more endo-mesomorphic than backs and with a greater scatter about their mean. The anthropometric variables that best discriminated between backs and forwards were body mass, femur breadth and arm girth, with 88% correctly classified using these variables. The motor performance variables that best discriminated between backs and forwards were repeated jump in place, push-up and standing vertical jump, with 76% correct classification using these variables. Classification into three playing levels was unsatisfactory using either anthropometric or motor performance variables. These data can be used to assess present status and change in players, or potential national players, by position to locate strengths and weaknesses.

Abdominal Muscles↗
PubMed1993

Five-year radiographic follow-up of extensive mandibular fixed partial dentures.

A group of patients with severely reduced dentitions were restored with 12-unit mandibular fixed partial dentures supported on the two canines and maxillary complete dentures. Eight patients were followed radiographically for 2 years and five of these for up to 5 years. Orthopantomograms, lateral and oblique-lateral cephalograms and intraoral radiographs were used. There were no great radiographically detectable changes either around the abutments or in the jaws. Six of the eight bridges tilted distally during the first 2 years. This downward tilting of the distal parts of the bridge resulted in a marked resorption under the cantilever sections in some patients.

Aged↗
PubMed1992

Masticatory function in patients with extensive fixed cantilever prostheses.

Eleven patients with complete maxillary dentures and 12-unit fixed partial dentures that included the mandibular canines were studied before and during specific intervals after prosthodontic treatment. Established methods for evaluation of oral function were used and the last examination was performed 30 months after treatment. All patients reported that their masticatory function had been substantially improved and there were no symptoms of dysfunction in the masticatory system. Masticatory efficiency improved after the prosthodontic treatment because both the number of cycles before the initial swallow and the total number of strokes including the time for completed mastication diminished after treatment. The occlusal force elevated after the prosthodontic treatment. Although great individual variations were recorded for all occasions and force levels, forces recorded on the extensions of the cantilever were similar to those on the canine regions.

Bite Force↗
PubMed1990

Human values and marijuana use.

The purpose of this study was to examine the relationship between prioritized rankings of human values among persons who either use or do not use marijuana. Discriminant analyses indicated that personal values are more important to marijuana users, while social values are more important to nonusers. Based upon the present study and previous research, the existence of a value orientation predisposing some individuals toward substance experimentation and use is suggested.

Adolescent↗
PubMed1989

Cinefluoroscopic study of long-term changes of bolus position and chewing cycle duration after fixed prosthetic treatment.

Some chewing parameters were studied in 12 patients with a complete maxillary denture and a 12-unit fixed mandibular denture anchored to the two canines. Registration by means of fluoroscopy were made before, 1 month after, and in four patients 13 yr after treatment. The mean velocity of the mandible during chewing increased after the prosthetic treatment and remained stable for meat during the observation period. At the first registration, before treatment, the bolus was most frequently located in the anterior region. After completion of the prosthetic rehabilitation, the bolus was mainly located to the lateral segments during chewing of the test foods, namely meat and bread. The recordings were almost identical 13 yr later. Despite a very reduced periodontal support, posterior cantilevered segments were satisfactorily used in comminution and the patients seemed to be unaware of the forces exerted on the remaining teeth.

Adult↗
PubMed1984

Endocrine and genetic characterization of cousins with male pseudohermaphroditism: evidence that the Lubs phenotype can result from a mutation that alters the structure of the androgen receptor.

Impaired virilization of genetic males with testes (male pseudohermaphroditism) can result either from deficiency in androgen production or defects in androgen action, the latter most commonly involving an abnormal androgen receptor. We report here two maternal cousins with male pseudohermaphroditism and clinical features characteristic of the Lubs phenotype, namely apparent females with sufficient fusion of the labioscrotal folds so that a single urogenital sinus orifice is present. Testosterone levels in these genetic males rose appropriately after administration of human chorionic gonadotropin. The amount (maximal binding capacity of 24 to 30 fmol/mg protein) and hormone binding affinity (half-maximal saturation of 0.2 nM) of the androgen receptor in cultured skin fibroblasts was normal, but the receptor was qualitatively abnormal as evidenced by instability on sucrose density gradient centrifugation. The pattern of inheritance in this family is compatible with X-linkage. These findings, together with previous studies, indicate that the spectrum of abnormalities that result from defects of the androgen receptor in genetic men can encompass the entire spectrum between male and female phenotypes.

Chorionic Gonadotropin↗
PubMed1984

A mutation that causes lability of the androgen receptor under conditions that normally promote transformation to the DNA-binding state.

Dihydrotestosterone-receptor complexes formed in human fibroblast cytosol prepared at 0 degrees C in the presence of sodium molybdate can be readily transformed to the DNA-binding state by heating at 25 degrees C. Under these conditions 50-70% of dihydrotestosterone-receptor complexes bind to DNA. We describe here studies of the transformation process in cytosols derived from normal cells and from fibroblasts propagated from subjects with syndromes of androgen resistance. In contrast to the situation with dihydrotestosterone, normal testosterone-receptor complexes are unstable under in vitro transforming conditions. Although equal amounts of hormone-receptor complex are formed at 0 degrees C, only 15% of testosterone-receptor complexes remain stable and acquire DNA-binding capacity after warming. This instability is not reversible upon lowering the temperature and is corrected by low concentrations (0.25 microM) of the protease inhibitor leupeptin. We have also identified two cousins with androgen resistance whose androgen-receptor complexes exhibit similar in vitro transformation lability with both dihydrotestosterone and testosterone. Phenotypic evidence in these subjects indicates that dihydrotestosterone-mediated processes are more completely impaired than are testosterone-mediated events. These findings suggest that dihydrotestosterone may amplify the androgenic signal at its targets not only by its higher affinity for the receptor but also by its more efficient conversion to the DNA-binding state and that such amplification may be less critical in target tissues in which testosterone suffices for androgenic effect. This offers one possible explanation of how a mutation that affects a single receptor protein may differentially impair the actions of two binding ligands of the receptor.

Child, Preschool↗
PubMed1978

Giant cell transformation cerebrohepatorenal syndrome.

An infant with cerebrohepatorenal syndrome of Zellweger had extensive hepatic giant cell transformation at 6 1/2 weeks of age. At 16 weeks the liver showed early cirrhosis and rare giant cells. Changes previously described have ranged from no abnormality in the neonate to cirrhosis at 20 weeks of age and indicate progression of liver disease in affected patients.

Abnormalities, Multiple↗