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Biomedical subjects

R A Bell

Publications and source records attributed to R A Bell.

At least 145 records · Page 8Linked to original sources
PubMed1981

Change and psychopathology: epidemiologic considerations.

The authors report data collected on 3674 subjects between 1970 and 1974 as part of an epidemiologic field survey of mental disorder in the southeastern United States, an area which was undergoing rapid sociocultural change. Rates of mental disorder, as measured by the Global Psychopathology Scale, are presented for various sociodemographic groups and are consistent with trends found in previous studies. Analysis of variance and multiple regression techniques are used to explore the relationships among awareness of social change, sociodemographic variables, and psychopathology. Low awareness of change is found to be consistently associated with low psychopathology scores across all socioeconomic groups. The authors postulate a "denial" or "filter" mechanism which may protect particularly vulnerable individuals from the psychic distress accompanying social change.

Adolescent↗
PubMed1981

The effects of maxillary expansion using a quad-helix appliance during the deciduous and mixed dentitions.

Ten subjects, five in the deciduous dentition and five in the mixed dentition (mean age = 6 years 9 months), had functional posterior cross-bites successfully corrected with fixed lingual arch wire expansion appliances of the quad-helix design. The appliance, in the context of "early" treatment, produced midpalatal suture separation on each subject as evidenced on occlusal radiographs. While the relative orthopedic and orthodontic changes were not determined, the maxillary intermolar and intercanine transverse measurements showed significant increases in all subjects, with mean values of +5.3 mm. and +4.1 mm., respectively. The active phase of treatment averaged 30 days and 1.1 adjustments for the desired expansion to be achieved. Incorporating a standard 6-week retention period, the total appliance wear time had a mean value of 75 days. Following a 3-month postretention adjustment period, relapse of the intermolar and intercanine transverse dimensions presented mean decreases of -1.5 mm. and -1.9 mm., respectively. The relapse potential was successfully compensated for by overexpansion of 2 to 3 mm. during the active phase of treatment. No significant differences were demonstrated between the deciduous- and mixed-dentition groups during the course of maxillary expansion with the quad-helix appliance.

Child↗
PubMed1981

The initial impact of a surgical AHES program on medical students' career decisions.

Since 1974 the University of Louisville has sent medical students to a rural area to receive their core surgical clerkship experience as part of an area health education system (AHES) program. This report reviews the first five years of the program and its effect on residency selection. Seventeen percent of the 679 students who graduated from the School of Medicine between 1976 and 1980 participated in this rural program. These students were similar to their urban university-based peers as a group in preclerkship evaluation criteria. Test scores on surgery examinations and examinations of the National Board of Medical Examiners did not differ between the two groups. Residency programs chosen by participants showed a similar distribution to those chosen by the university group, except in family practice. Twenty-six percent of the rural group chose family practice residencies, compared with 16 percent of the urban group. The early impact of the surgical AHES program is evaluated, and the need for continued follow-up is emphasized.

Career Choice↗
PubMed1981

Prosthodontic treatment of pendulous maxillary tuberosities.

Reduction of the maxillary tuberosities is not always possible when indicated, and it is sometimes necessary to solve the problem by modifying the construction procedures for the complete denture. Because of inadequate space between the maxillary tuberosity and the retromolar pad, acrylic bases of adequate thickness could not be used. Instead, gold shims 1-min thick were cast over the tuberosities. They had loops around the periphery and V-shaped recesses to allow for even finishing of the wax-up of the record base to the gold shims. Jaw relation records were made and the teeth were set in bilateral crossbite because of the discrepancy in arch size. The acrylic resin was then processed, the dentures finished and polished, and normal laboratory and clinical remount procedures observed. Because there was some space available, this technique worked well. Both tuberosities and retromolar pad areas may also be cast in gold to allow for even thinner base in this area; however, when surgical reduction is possible, it is still the preferable treatment.

Aged↗
PubMed1981

Actinomycosis. A cause of pulmonary and mediastinal mass lesions in children.

Two patients with intrathoracic actinomycosis were examined. One child was asymptomatic and had a slowly expanding lesion in the left upper lobe. The other child had a chronic illness with back pain, weight loss, amenorrhea, and a posterior mediastinal mass. Establishing the cause of these lesions and making the distinction between a neoplastic process and infection were particularly difficult in both cases. Intrathoracic actinomycosis should be considered in the differential diagnosis of pulmonary and mediastinal mass lesions.

Actinomycosis↗
PubMed1981

Tapioca melanoma of the iris: clinicopathological correlation with results of fluorescein angiography.

A tapioca melanoma in a 75-year-old Caucasian man was shown by light microscopy to consist of spindle B cells with abundant vesicular cytoplasm, minimal pigmentation and surface nodularity that correlated with the gross appearance. Electron microscopy showed spindle shaped cells with multiple premelanosomes and melanin granules. Iris angiography demonstrated an irregular crisscrossing vascular network with a papillary configuration and fluorescein leakage confined to the tumour. The clinical appearance of the lesion and the angiographic findings are characteristic of this unusual variant of iris melanoma and help distinguish it from granulomatous iritis and from neurofibroma, leiomyoma and metastatic carcinoma of the iris.

Adult↗
PubMed1980

Depression in family practice patients.

Multiple factors have been described as significant contributors to depression in medical patients. This study attempts to assess the relative significance and interrelationship of variables associated with depression. A group of 199 family practice patients were studied. Using a multivariate research design, significant depressive symptoms were found in 41% of the sample. A stepwise multiple regression analysis revealed that the five most important factors associated with depression, in order of significance, were socioeconomic status, recent stress, use of birth control pills, serious physical illness, and distant life events. This study supports the thesis that depression is a final common pathway syndrome in which biologic and social forces coalesce into syndrome expression. The primary care practitioner needs to be aware of the multiple risk factors for depression to develop effective detection and intervention strategies.

Depression↗
PubMed1980

The effects of base sequence and dangling bases on the stability of short ribonucleic acid duplexes.

Variable temperature proton nuclear magnetic resonance spectroscopy is used to establish that both sequence and dangling bases affect stability of short RNA double helices. Tetraribonucleotides, CAUG, UGCA and AGCU form reference duplexes (Tm 25 degrees, 33 degrees, 34 degrees, respectively) which contain an equal number of G . C and A . U base pairs and which show primary sequence is important. Pentaribonucleotides GAUGA, ACAUG, UGCAA and AGCUA, form duplexes (Tm 36 degrees, 35 degrees, 46 degrees, 45 degrees, respectively) with dangling adenines. Average Tm difference from the reference is +11 degrees for two 3' or 5'-dangling adenines. Pentaribonucleotides, CAUGU and UCAUG, form duplexes (Tm both 30 degrees) with dangling uracils. Average Tm difference from the reference is +5 degrees for two 3' or 5'-dangling uracils. Fraying was detected only in duplexes from the AGCU series. Presence of a dangling adenine, in duplex, AGCUA, caused a reduction in fraying.

Base Composition↗
PubMed1979

Effects of internal nonbonded bases and a G.U base pair on the stability of a short ribonucleic acid helix.

Proton nuclear magnetic resonance has been used to examine the effect of both noncomplementary and G.U oppositions in the duplexes formed by the synthetic pentaribonucleotides CpApApUpG, CpApUpUpG, CpApGpUpG, and CpApCpUpG. The lack of any sigmoidal behavior in the chemical shift vs. temperature plots of the base protons in the individual pentaribonucleotides indicates that duplexes with noncomplementary base oppositions of the type: formula: (see text), (where X = A, U, G, or C) do not form. Variable temperature spectra of the mixture of CpApGpUpG and CpApUpUpG were recorded over the range of 70--10 degrees C. The chemical shift vs. temperature plot of the purine aromatic protons displayed sigmoidal curves. This demonstrated both duplex formation and the presence of a G.U. base pair. The average Tm of the duplex was found to be 23.4 +/- 2.0 degrees C. This is similar to that of the duplex formed by CpApUpG (24.0 +/- 1.0 degrees C) but less than the Tm of the following duplexes: CpApApUpG:CpApUpUpG (Tm = 28.5 +/- 2.1 degrees C), CpApGpUpG:CpApCpUpG (Tm = 38.4 +/- 0.6 degrees C) and CpApUpApUpG (Tm = 41.5 +/- 1.1 degrees C). The G.U base pair has a Tm (20.0 degrees C) significantly lower than the rest of the duplex (24 +/- 1 degree C) and is a region of local instability within the double helix. This 1H NMR study is the first to investigate both the formation and relative stability of an internal G.U. base pair neighboring regular Watson--Crick base pairs.

Base Composition↗
PubMed1978

Ciliary muscle dysfunction in Adie's syndrome.

Ciliary muscle function in patients with Adie's syndrome was studied retrospectively in 122 patients and prospectively in 17 patients. When a careful history was taken, two thirds of the patients had ciliary muscle-related symptoms. Most of the patients with Adie's syndrome had a moderate accomodative paresis, but there was a strong tendency for the ciliary muscle to recover with time. Many patients showed a tonicity of accommodation, especially those who had had the condition for several years. Astigmatism could be induced with accommodation in one third of patients. This may be related to segmental paralysis of the ciliary muscle. Seventy-three percent of the patients showed supersensitivity of the ciliary muscle in the involved eye, when both eyes were treated with a mixture of 0.25% pilocarpine hydrochloride and hydroxypropyl methylcellulose (Isopto Carpine). This may be a clinical aid in diagnosing Adie's syndrome. Two patients were found to have bilateral ciliary muscle dysfunction but only unilateral pupillary abnormalities. These two patients may have had a "pupil-sparing" Adie's syndrome.

Accommodation, Ocular↗