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Biomedical subjects

J R Bell

Publications and source records attributed to J R Bell.

At least 19 recordsLinked to original sources
PubMed1991

Significant efficiency findings while controlling for the frequent confounders of CAI research in the PlanAlyzer project's computer-based, self-paced, case-based programs in anemia and chest pain diagnosis.

Richard E. Clark in his widely published comprehensive studies and meta-analyses of the literature on computer assisted instruction (CAI) has decried the lack of carefully controlled research, challenging almost every study which shows the computer-based intervention to result in significant post-test proficiency gains over a non-computer-based intervention. We report on a randomized study in a medical school setting where the usual confounders found by Clark to plague most research, were carefully controlled. PlanAlyzer is a microcomputer-based, self-paced, case-based, event-driven system for medical education which was developed and used in carefully controlled trials in a second year medical school curriculum to test the hypothesis that students with access to the interactive programs could integrate their didactic knowledge more effectively and/or efficiently than with access only to traditional textual "nonintelligent" materials. PlanAlyzer presents cases, elicits and critiques a student's approach to the diagnosis of two common medical disorders: anemias and chest pain. PlanAlyzer uses text, hypertext, images and critiquing theory. Students were randomized, one half becoming the experimental group who received the interactive PlanAlyzer cases in anemia, the other half becoming the controls who received the exact same content material in a text format. Later in each year there was a crossover, the controls becoming the experimentals for a similar intervention with the cardiology PlanAlyzer cases. Preliminary results at the end of the first two full trials shows that the programs have achieved most of the proposed instructional objectives, plus some significant efficiency and economy gains. 96 faculty hours of classroom time were saved by using PlanAlyzer in their place, while maintaining high student achievement. In terms of student proficiency and efficiency, the 328 students in the trials over two years were able to accomplish the project's instructional objectives, and the experimentals accomplished this in 43% less time than the controls, achieving the same level of mastery. However, in spite of these significant efficiency findings, there have been no significant proficiency differences (as measured by current factual and higher order multiple choice post-tests) between the experimental and control groups. Very careful controls were used to avoid what Clark has found to be the most common confounders of CAI research. Accordingly, this research proved Clark's rival hypothesis, that the computer, in itself, does not appear to contribute to proficiency gains, at least as measured by our limited post-testing. Clark's position is that the computer is primarily a vehicle--as is either a pill or a hypodermic needle for delivering a drug.(ABSTRACT TRUNCATED AT 400 WORDS)

Anemia↗
PubMed1991

A clinicopathological study of adenocarcinoma in situ of the cervix. The influence of cervical HPV infection and other factors, and the role of conservative surgery.

Adenocarcinoma in situ (ACIS) of the uterine cervix is an increasingly recognized disease. Thirty-seven cases were reviewed to determine the effect of HPV, marital status, parity, smoking habit and age on the topography and behaviour of this lesion. Using a commercial probe, 25% of 28 lesions tested were positive for HPV 16/18. The presence of HPV and a history of smoking appeared to exert no significant influence upon the topography and behaviour of ACIS. Nulliparity and a history of never being married was associated with a significant reduction in the incidence of coexisting CIN lesions. Age less than 36 years was associated with a significant reduction in the proximal linear extent of ACIS. While hysterectomy is probably the definitive treatment for ACIS of the cervix, there is an important place for conservative management by conization alone. Patients younger than 36 years are most likely to be desirous of retained fertility and appear to have the lesions most amenable to conservative surgery.

Adenocarcinoma↗
PubMed1991

Ovarian follicular non-Hodgkins lymphoma.

Non-Hodgkins Lymphoma presenting in and confined to the ovaries is a rare occurrence. A follicular histological pattern has been reported only occasionally in this setting. A case of follicular mixed small cleaved and large cell lymphoma, discovered incidentally and limited to the ovaries is reported. Immunological marker studies revealed a monoclonal population of B lymphocytes with surface Ig A Kappa. A review of cases in the literature suggests that follicular histology in stage I ovarian disease confers an outcome similar to that for follicular nodal disease.

Adult↗
PubMed1991

Findings from an evaluation of PlanAlyzer's double cross-over trials of computer-based, self-paced, case-based programs in anemia and chest pain diagnosis.

We report on three years of research trials of the PlanAlyzer I Project--a carefully controlled research study using a microcomputer-based, self-paced, case-based, event-driven system for medical education. PlanAlyzer presents cases, elicits and critiques a second year student's approach to the diagnosis of anemias and chest pain. PlanAlyzer uses text, hypertext, images and critiquing theory. Students were randomized, one half becoming the experimental group who received the interactive PlanAlyzer cases in anemia, the other half becoming the controls who received the exact same content material in a text format. Later in each year there was a crossover, the controls becoming the experimentals for a similar intervention with the cardiology PlanAlyzer cases. Results at the end of the first two years of trials show that the programs have achieved some significant efficiency and economy gains. 96 faculty hours of classroom time were saved by using PlanAlyzer in their place, with no loss in student achievement. In terms of student proficiency and efficiency, combining the anemia and cardiology trials, the 328 students in the two years of full scale trials were able to accomplish the project's instructional objectives. The experimentals accomplished this in 43% less time than the controls. On the average, for both the anemia and chest pain programs, this amounted to students spending 7.5 hours longer on the 30 text cases than on the same 30 computer cases to achieve the same level of mastery. There have been no significant proficiency differences (as measured by current post-tests) between the experimental and control groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Anemia↗
PubMed1990

Physician variation in anticoagulating patients with atrial fibrillation. Dartmouth Primary Care COOP Project.

We investigated variations in the oral anticoagulant treatment of atrial fibrillation by physicians in three specialties: family physicians (or general practitioners), general internists, and cardiologists. Results showed general agreement in the anticoagulation decision regarding patients with either mitral valve disease or a history of chronic alcohol abuse, but substantial disagreement in other categories of patients. Estimations of the risk of embolization and risk of hemorrhage differed widely among all physicians, cardiologists generally rating the embolization risks lower than the other physicians. A physician's treatment decision was strongly related to the relative risk of embolism vs hemorrhage derived for each case. A relationship between physician specialty and treatment decision was also demonstrated, with cardiologists least likely, and family practitioners most likely, to institute anticoagulation in nonrheumatic patients with atrial fibrillation. The reason for this variation appears to be differences in the estimated risk of systemic embolism.

Aged↗
PubMed1988

In vivo determination of ATP in tumors using 31P inversion spin transfer.

The in vivo exchange kinetics of creatine kinase in the hind leg muscle of rats containing a transplanted mammary adenocarcinoma has been investigated using 31P magnetic resonance spectroscopy. Using a solenoid coil, the adenosine triphosphate (ATP) resonances arising from the tumor could be distinguished from ATP resonances arising from the muscle surrounding the tumor by use of inversion spin transfer techniques. This procedure affords a specific method of evaluating ATP metabolism of tumors in vivo.

Adenocarcinoma↗
PubMed1987

Use of high resolution in vivo volume selected 1H-magnetic resonance spectroscopy to investigate leukemia in humans.

In vivo high resolution volume-selected 1H magnetic resonance spectroscopy of human tibia has been undertaken using spatial coordinates obtained from magnetic resonance images. Adult tibial marrow has a 1H spectrum rich in fatty acid resonances and is readily distinguished from the 1H spectra of surrounding leg muscle. In all four leukemic patients examined, infiltration of fat cells of tibial marrow by proliferating cells rich in mobile H2O protons was evident by magnetic resonance imaging. Selective examination of volumes of tibial marrow (1 cm3) by 1H magnetic resonance spectroscopy confirmed marked differences in the 1H spectra of marrow from these patients. Increases in the H2O peak of the 1H spectra were correlated with infiltration of blast cells and lack of control of the neoplastic disease. These studies are the first to report the use of volume selected magnetic resonance spectroscopy to selectively monitor leukemia in humans.

Adolescent↗
PubMed1987

Diagnostic trends in childhood chromosome abnormalities and their implications--a total population eight-year survey from Queensland, Australia.

The data from an ongoing total population survey of all diagnosed chromosome anomalies in Queensland, Australia have been presented for an 8-year period (1976-83). A total of 760 patients was diagnosed, principally autosomal trisomies (431) and sex chromosome abnormalities (126). Nearly half of total childhood diagnoses (up to 14 years) were made in the first week. Virtually all expected cases of autosomal trisomies were detected in the first month. The largest component of the pool of unrecognized childhood disorders in this study was the sex chromosome group. This failure of detection has implications in terms of potentially beneficial hormone treatment and predisposition to neoplasia.

Adolescent↗
PubMed1986

Partial N-terminal amino acid sequences of three nonstructural proteins of two flaviviruses.

Partial N-terminal amino acid sequences for the three largest nonstructural proteins of two flaviviruses, yellow fever virus and St. Louis encephalitis virus, have been obtained. The determined sequences of these proteins exhibit significant amino acid sequence homology, and allow the positioning of these three nonstructural proteins in the polyprotein sequence deduced from the nucleotide sequence of yellow fever virus (C. M. Rice, E. M. Lenches, S. R. Eddy, S. J. Shin, R. L. Sheets, and J. H. Strauss, 1985, Science 229, 726-733.) The deduced start points support the hypothesis that the N terminus of nonstructural glycoprotein NS1 results from cleavage by signalase, whereas the N termini of NS3 and NS5 result from cleavages following double basic residues that are flanked by amino acids with short side chains.

Amino Acid Sequence↗
PubMed1985

Primary structure of the cleavage site associated with trypsin enhancement of rotavirus SA11 infectivity.

The primary structure of the trypsin cleavage site in the outer layer protein VP3 of rotavirus SA11 was determined. This cleavage enhances the infectivity of rotavirus SA11. Both VP8, one of the polypeptides generated by the cleavage, and VP3 had their alpha-NH2 blocked. Only VP5, the other polypeptide produced by the cleavage, was susceptible to sequential Edman degradation, indicating that it contained the new alpha-NH2 terminus generated by trypsin hydrolysis. The results indicated that purified VP5 is composed of two polypeptides with the following amino acid sequence at their N terminus: (a) ??VYTRAQPNQDAVVSKTS...; (b) AQPNQDAVVSKTS.... Sequencing of the DNA complementary to ds RNA segment 4 revealed a nucleotide sequence encoding the amino acid sequences indicated above, with only one different amino acid. From these results, the amino acid sequence of the site cleaved by trypsin was extended to cover the C termini (present in VP8). The following sequence, which contains two sites (indicated with asterisks) and can be cleaved by trypsin was deduced: ... VPVSIVSR*NIVYTR*AQPNQDIVVSKTS....

Amino Acid Sequence↗
PubMed1985

A new copia-like transposable element found in a Drosophila rDNA gene unit.

We have discovered a member of a new family of copia-like transposable elements inserted into the non-transcribed spacer between two ribosomal genes (rDNA). This family, which we call 3S18, consists of at least 15 elements which are scattered throughout the Drosophila melanogaster genome. The elements of this family are approximately 6.5 kb long and have 0.5 kb terminal direct repeats. All of the elements appear to have the same restriction sites. The element is mobile as the size pattern of homologous fragments varies among different strains. In situ hybridization results confirm the scattered location and transposable qualities of 3S18. The element is not transcribed into abundant RNA.

Animals↗
PubMed1985

Amino-terminal amino acid sequences of structural proteins of three flaviviruses.

N-terminal amino acid sequences of structural proteins of three flaviviruses, yellow fever, St. Louis encephalitis, and dengue-2 viruses, have been obtained. The glycoproteins of these three viruses are 52-60% conserved in the region sequenced, depending upon which pair of viruses are compared, and 40% of the amino acids are invariant in all three viruses. Thus, flaviviruses are closely related and have in all probability descended from a common ancestor. Furthermore, residues important in the secondary structure of proteins are conserved, suggesting that the overall conformation of the glycoproteins is the same in all three viruses while considerable variation in the primary sequence can be accommodated. The N-terminal regions of the nucleocapsid proteins of yellow fever and St. Louis encephalitis viruses show markedly less homology (25%) and this region is highly basic with one-quarter (yellow fever) or one-third (St. Louis encephalitis) of the residues being lysine or arginine. N-terminal sequences for the M protein of yellow fever and for NV2(GP19) of St. Louis encephalitis viruses are also reported.

Amino Acid Sequence↗
PubMed1978

Amino-terminal sequence analysis of the structural proteins of Sindbis virus.

The structural proteins of Sindbis virus, an enveloped virus which belongs to the Togavirus family, have been subjected to automated Edman degradation using improved techniques. Extensive NH2-terminal sequences of about 50 residues were determined for each of the two membrane glycoproteins. In both cases the NH2 terminus of the molecule was found to be similar in composition to typical water-soluble proteins. The viral capsid protein was found to have a blocked alpha-amino group. This is consistent with other observations that viral proteins derived from the NH2 terminus of precursor molecules are often blocked.

Amino Acid Sequence↗
PubMed1975

Results of surgery for Crohn's disease in the Glasgow region, 1961-70.

During the period 1961-70, 283 patients in the Glasgow region have been studied with regard to the outcome of 418 surgical procedures performed for Crohn's disease. Resection was followed by an overall recurrence rate of 33 per cent, but in disease confined to the large bowel the rate was 18 per cent. Exploratory operations and bypass procedures were followed by a recurrence rate of 70 per cent. Evidence is provided that recurrence following bypass procedures for small bowel disease and ileocolitis occurs at a later stage than after exploratory operations alone. By the end of the study 77 per cent of patients in this series had required one or more resections.

Crohn Disease↗