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Biomedical subjects

J R Bell

Publications and source records attributed to J R Bell.

At least 55 records · Page 3Linked to original sources
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

Pattern of glycosylation of Sindbis virus envelope proteins synthesized in hamster and chicken cells.

The tryptic glycopeptides of the Sindbis virus envelope glycoproteins E1 and E2 grown in BHK and chick cells were purified by gel filtration followed by high-pressure liquid chromatography. Each of the purified glycopeptides was analyzed by N-terminal sequencing to identify from which of the potential glycosylation sites it was derived. The type of oligosaccharide chain attached to each glycopeptide was determined from gel filtration analysis of the pronase-digested glycopeptides, and the relative incorporation of radiolabeled galactose, mannose, and glucosamine into each glycopeptide was used to confirm these determinations. The glycosylation patterns for the two proteins were essentially identical in the two host cells. The E2 glycosylation sites at Asn196 and Asn318 contained exclusively complex-type and simple-type oligosaccharide chains, respectively. In E1, the glycosylation site at Asn139 contained only complex-type chains, but the site at Asn245 contained a mixture of simple (75-85%) and complex (15-25%) type chains. These results are discussed in relation to previously reported results and a prediction as to the relative importance of the different glycosylation sites to the function of the proteins is made.

Amino Acid Sequence↗
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↗
PubMed1985

The nonstructural proteins of Sindbis virus as studied with an antibody specific for the C terminus of the nonstructural readthrough polyprotein.

A dodecapeptide containing the sequence of the C terminus of the nonstructural polyprotein of Sindbis virus has been synthesized and used to immunize rabbits. The antisera obtained precipitated polypeptides from cells infected with the HR strains of Sindbis or with temperature-sensitive mutants ts11 or ts18. Four different polypeptides, having apparent molecular weights of approximately 250,000, 220,000, 155,000, and 72,000, were immunoprecipitated by the antipeptide antiserum. The largest of these polypeptides is sufficiently large to represent a polyprotein translated from the entire nonstructural region of the genome. These data suggest that nsP4 of molecular weight 72,000 is produced by translation of the entire nonstructural region of the genome, which requires readthrough of an opal termination codon immediately upstream of nsP4, followed by post-translational cleavage of this polyprotein. The amounts of nsP4 and its precursors found in infected cells are small relative to the amounts of other nonstructural proteins present, as would be expected if readthrough of a termination codon is required. In addition, the relative amounts of nsP4 and of its precursors differ in HR-infected or ts mutant-infected cells and differ with temperature of infection, suggesting that temperature of infection or ts lesions affect translation and processing of the precursor polyprotein.

Animals↗
PubMed1985

Bacterial expression of the acquired immunodeficiency syndrome retrovirus p24 gag protein and its use as a diagnostic reagent.

A retrovirus [lymphoadenopathy-associated virus, human T-cell leukemia virus type III, acquired immunodeficiency syndrome (AIDS)-related virus] suspected of causing AIDS has been isolated recently. The detection of exposure to this retrovirus in donors of various blood products is important to prevent transmission of the disease from these donors to recipients. In the majority of cases, the detection of antibodies directed against either the viral core protein, a Mr approximately equal to 24,000 protein termed p24 gag, or the viral envelope antigen is proof of previous viral infection. Thus, we have expressed the p24 gag antigen in Escherichia coli in order to produce a diagnostic reagent for the detection of virus exposure. The bacterially synthesized antigen reacts with human and rabbit antisera directed against the native p24 gag protein in both electrophoretic transfer blot assay and ELISA. In addition, the use of bacterially produced antigens for ELISAs gave results that were comparable to those obtained by using antigens isolated from the virus.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Characterization of Barmah forest virus: an alphavirus with some unusual properties.

Barmah Forest virus has been characterized in a number of ways including electron microscopy of infected cells; physical studies of the virion, its RNA, and associated proteins; N-terminal sequence analysis of the two envelope glycoproteins; studies of macromolecular species present in infected cells; and serological cross-reactions with alphaviruses and bunyaviruses. From these results Barmah Forest virus is clearly an alphavirus since the structure of the virion, the mode of replication, and the macromolecular species present in infected cells are typical of alphaviruses. The N-terminal regions of the two glycoproteins E1 and E2 show extensive sequence homology (approximately 50%) with those of other alphaviruses. Barmah Forest virus cross-reacts in hemagglutination inhibition tests, although not in complement fixation tests or infectivity neutralization tests, with other alphaviruses. In some of its properties Barmah Forest virus is unusual, however. It cross-reacts in complement fixation and hemagglutination inhibition tests with Umbre virus, a bunyavirus, which originally led it to be classified as a bunyavirus; the glycosylation pattern of E2 of Barmah Forest virus appears to differ from that of other alphaviruses; and the sedimentation coefficient of the virion appears to be slightly less than that of other alphaviruses.

Aedes↗
PubMed1984

An evolutionary tree relating eight alphaviruses, based on amino-terminal sequences of their glycoproteins.

The NH2-terminal amino acid sequences of both structural glycoproteins of each of eight alphaviruses have been obtained. These sequences demonstrate that the alphaviruses are all closely related and have in all probability descended from a common ancestor. Cysteines are conserved as well as several other residues important for secondary structure, suggesting that the three-dimensional conformations of the alphavirus glycoproteins are conserved while considerable variation in the primary sequence has evolved. Secondary structure predictions based upon the amino acid sequences are consistent with this hypothesis. An evolutionary tree for these eight alphaviruses has been constructed from the amino acid sequence data and, at many positions in the sequence, the amino acids present in the ancestral glycoproteins have been deduced.

Alphavirus↗