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Biomedical subjects

D Roberts

Publications and source records attributed to D Roberts.

At least 55 records · Page 3Linked to original sources

The shorthand publications of Sir William Richard Gowers.

OBJECTIVE: To examine the shorthand publications of Sir William Richard Gowers. BACKGROUND: Gowers developed an almost obsessional interest in Pitman shorthand. During the later part of his active career (1894-1910), the bulk of his professional writing, comprising nearly 100 articles, was printed entirely in Pitman shorthand in the Phonographic Record of Clinical Teaching and Medical Science. The obscurity and rarity of this periodical, and the increasingly arcane nature of Pitman shorthand, has left the bulk of these articles "buried in obscurity and locked up in code" (M. Critchley, 1949). DESIGN/METHODS: A complete set of Gowers' shorthand publications as listed in his standard bibliography was compiled. Transcription of the Pitman shorthand outlines was performed by a qualified Pitman shorthand transcriber and verified using the contemporaneous Phonographic Outlines of Medical Terms (1902) as an authoritative guide. RESULTS: The first transcription of Gowers' shorthand publications has now been completed. The history of Gowers' interest in shorthand and his efforts to proselytize the medical profession is reviewed. Selected excerpts are presented from his shorthand articles, which include papers devoted to problems in practical diagnosis, notes on clinical teaching, and the shorthand transcriptions of his lectures at Queen Square and at University College Hospital on such diverse subjects as myelitis, neurosyphilis, polio, muscular dystrophy, tumors, vascular disease, epilepsy, and the nervous system in old age. CONCLUSIONS: The previously unpublished transcriptions of his shorthand articles represent a major and previously inaccessible part of Gowers' neurologic opus. These articles exemplify Gowers as a practicing neurologist and teacher, and significantly expand our insights into one of neurology's most significant and influential figures.

England↗

Mathematical elements of attack risk analysis for mountain pine beetles.

Three different mathematical approaches are combined to develop a spatial framework in which risk of mountain pine beetle (MPB) attack on individual hosts may be assessed. A density-based partial differential equation model describes the dispersal and focusing behavior of MPB. A local projection onto a system of ordinary differential equations predicts the consequences of the density equations at individual hosts. The bifurcation diagram of these equations provides a natural division into categories of risk for each host. A stem-competition model links host vigor to stand age and demographics. Coupled together, these models illuminate spatial risk structures which may also shed light on the role of climatic variables in population outbreaks. Preliminary results suggest that stand microclimate has much greater influence on risk of attack than host vigor and stand age.

Animals↗

Drugs on money.

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Forensic Medicine↗

Novel and selective calcitonin-inducing agents.

A series of xanthine sulfonamides is presented as a class of calcitonin (CT) inducers - a potentially new method for treating diseases associated with postmenopausal bone loss such as osteoporosis. We have found that certain di-n-butylxanthine sulfonamides 4 upregulate CT transcription in a CT-luciferase reporter gene assay (CT-luci) and increase the production and release of CT in a CT secretion/RIA assay (CTS). In addition, these compounds do not have potent PDE4 inhibitory activity as do the related xanthine methylene ketones such as denbufyllene (2). One compound in particular (9) shows a transcription activation ratio (TAR) of 2.1 in CT-luci, a CTS increase of 3.6-fold, and a PDE4 (phosphodiesterase type IV) IC(50) = 4.1 microM. In addition, this compound showed a statistically significant 47% trabecular bone protection in ovariectomized-induced osteopenia (OVX) rats as determined by assay when administered for 4 weeks at 30 mg/kg/day, i. p. by quantitative computed tomography (QCT). When administered p.o., compound 9 shows 50% trabecular bone protection when administered for 3 weeks at 50 mg/kg/day, i.p. This compared with salmon CT which shows 62% trabecular bone protection when administered at 50 IU/kg/day for 4 weeks.

3',5'-Cyclic-AMP Phosphodiesterases↗

Derivation of a needs based capitation formula for allocating prescribing budgets to health authorities and primary care groups in England: regression analysis.

OBJECTIVE: To develop a weighted capitation formula for setting target allocations for prescribing expenditures for health authorities and primary care groups in England. DESIGN: Regression analysis relating prescribing costs to the demographic, morbidity, and mortality composition of practice lists. SETTING: 8500 general practices in England. SUBJECTS: Data from the 1991 census were attributed to practice lists on the basis of the place of residence of the practice population. MAIN OUTCOME MEASURES: Variation in age, sex, and temporary resident originated prescribing units (ASTRO(97)-PUs) adjusted net ingredient cost of general practices in England for 1997-8 modelled for the impact of health and social needs after controlling for differences in supply. RESULTS: A needs gradient based on the four variables: permanent sickness, percentage of dependants in no carer households, percentage of students, and percentage of births on practice lists. These, together with supply characteristics, explained 41% of variation in prescribing costs per ASTRO(97)-PU adjusted capita across practices. The latter alone explained about 35% of variation in total costs per head across practices. CONCLUSIONS: The model has good statistical specification and contains intuitively plausible needs drivers of prescribing expenditure. Together with adjustments made for differences in ASTRO(97)-PUs the model is capable of explaining 62% (35%+0.65% (41%)) of variation in prescribing expenditure at practice level. The results of the study have formed the basis for setting target budgets for 1999-2000 allocations for prescribing expenditure for health authorities and primary care groups.

Budgets↗

Search for rare and forbidden eta(') decays

We have searched for rare and forbidden decays of the eta(') meson in hadronic events at the CLEO II detector. The search is conducted on 4.80 fb(-1) of e(+)e(-) collisions at 10.6 GeV center-of-mass energy at the Cornell Electron Storage Ring. We find no signals, and set 90% confidence level upper limits of their branching fractions: B(eta(')-->e(+)e(-)eta)<2.4x10(-3), B(eta(')-->e(+)e(-)pi(0))<1. 4x10(-3), B(eta(')-->e(+)e(-)gamma)<0.9x10(-3), and B(eta(')-->e&mgr;)<4.7x10(-4). We also fit the matrix element of the eta(')-->pi(+)pi(-)eta Dalitz plot with the parametrization |M|(2) = A|1+alphay|(2), where y is a linear function of the kinetic energy of the eta, and find Re (alpha) = -0.021+/-0.025.

Journal Article↗

Prenatal detection of trisomy 21: combined experience of two British hospitals.

A retrospective study was performed to determine the detection rate of trisomy 21 in two British hospitals using a combination of: (1) second trimester serum screening with maternal age, alphaFP and hCG; (2) karyotyping for raised maternal age and high background risk of aneuploidy; and (3) second trimester fetal anomaly ultrasonography at 18-22 week gestation. 36-410 women with a median age of 27 years were studied. Trisomy 21 detected by the combination of methods in both hospitals was compared with the actual number of pregnancies affected by trisomy 21, to determine the detection rate. Serum screening as the backbone of the service detected 31/48 (65%) trisomy 21 affected pregnancies. Karyotyping for maternal age and previous aneuploidy detected eight trisomy 21 affected pregnancies, and second trimester ultrasound a further six, giving a total detection rate of 45/56 (80%). Thus, the detection rate of trisomy 21 in our population is 65% by serum screening alone. This is similar to demonstration projects, but the addition of second trimester ultrasonography and karyotyping for maternal age and prior risk, contributes further to improve the overall sensitivity to 80%. The invasive procedure rate was 4.8% of all women.

Adult↗

Bilateral proprioceptive defects in patients with a unilateral anterior cruciate ligament reconstruction: a comparison between patients and healthy individuals.

Proprioception of the knee was measured in 20 patients with reconstructed anterior cruciate ligaments and in 19 age-matched controls. The mean time from surgery was 2 years. Three tests of proprioception were used: (a) threshold to detection of passive motion from 20 and 40 degrees toward flexion and extension, (b) active reproduction of a 30 degrees passive angle change, and (c) visual reproduction of a 30 degrees passive angle change. The aim was a complete, bilateral, proprioceptive evaluation of patients who had undergone reconstruction of the anterior cruciate ligament. As compared with those in the control group, the knees with reconstructed anterior cruciate ligaments had a higher threshold to detection of passive motion in the extension trials from 20 and 40 degrees (p = 0.0003 and 0.04, respectively) and in the flexion trials from 20 and 40 degrees (p = 0.004 and 0.0008, respectively). When the uninjured knees of the patients were compared with those in the control group, higher values for threshold to detection of passive motion were found in the flexion trials from 20 degrees (p = 0.002) and 40 degrees (p = 0.02). Thus, decreased proprioceptive ability was present in some measurements of these patients after reconstructive surgery, not only in injured knees but also in uninjured knees, as compared with the reference group. The functional relevance of these findings was not investigated in this study, but the results suggest that bilateral proprioceptive considerations should be made when evaluating prognostic factors, treatment, and risk of contralateral knee injury in patients with reconstructed anterior cruciate ligaments.

Adult↗

Squamous cell carcinoma of the tongue in young adults: increasing incidence and factors that predict treatment outcomes.

OBJECTIVE: This study was designed to determine whether the incidence of squamous cell carcinoma of the oral tongue (SCCOT) in young adults has changed during the past 25 years and to determine prognostic factors for young adult patients (aged < 40 years) with SCCOT. METHODS AND PATIENTS: A retrospective review of young adults with SCCOT who sought treatment at the M. D. Anderson Cancer Center between 1973 and 1995 was undertaken. RESULTS: The percentage of young adult SCCOT patients at M. D. Anderson increased from 4% in 1971 to 18% in 1993. T stage, N stage, perineural invasion, and lymphatic invasion were all associated with decreased survival. Patients who received a neck dissection as part of their primary treatment had a better chance of survival than patients who did not. CONCLUSIONS: The incidence of SCCOT in the young adult population is increasing in the United States. Appropriate surgical management for young adults with SCCOT includes resection of the primary tumor along with a selective node dissection.

Adult↗

Adult and pediatric CPR: attitudes and expectations of health professionals and laypersons.

Nationally accepted resuscitation courses offer few guidelines for terminating unsuccessful cardiopulmonary resuscitation (CPR). Data were collected from 305 physicians and nurses in 1988/1989 and 401 physicians, nurses, and laypersons in 1998/1999 to assess their attitudes and expectations about adult and pediatric CPR. Respondents felt pediatric CPR efforts should continue longer than adult CPR efforts. Respondents in 1998/1999 felt CPR efforts did not need to continue as long as the 1988/1989 respondents felt. Laypersons thought that 52% of adult CPRs and 63% of pediatric CPRs were successful. Although lower than laypersons' expectations, health care professionals' expectations of CPR success were also unrealistic; physicians believed 24% of adult and 41% of pediatric CPRs were successful and nurses believed 30% of adult and 45% of pediatric CPRs were successful. Health care professionals also indicated that they had a clearer idea of when to terminate adult CPR than pediatric CPR.

Adult↗

Development of a PCR-based line probe assay for identification of fungal pathogens.

We report on a reverse-hybridization line probe assay (LiPA) which when combined with PCR amplification detects and identifies clinically significant fungal pathogens including Candida, Aspergillus, and Cryptococcus species. DNA probes have been designed from the internal transcribed-spacer (ITS) regions of Candida albicans, Candida parapsilosis, Candida glabrata, Candida tropicalis, Candida krusei, Candida dubliniensis, Cryptococcus neoformans, Aspergillus fumigatus, Aspergillus versicolor, Aspergillus nidulans and Aspergillus flavus. The probes were incorporated into a LiPA for detection of biotinylated ITS PCR products, and the specificity of the probes was evaluated. We established LiPA detection limits for ITS 1 and for full ITS amplicons for genomic DNA from C. albicans, A. fumigatus, and C. neoformans. Further evaluation of the LiPA was carried out on clinical fungal isolates. One hundred twenty-seven isolates consisting of dimorphic yeasts and dermatophytic and filamentous fungi were tested by the LiPA, which correctly identified 77 dimorphic yeasts and 23 of the filamentous isolates; the remaining 27 isolates represented species of fungi for which probes were not included in the LiPA. The fungal-PCR-LiPA technology was applied to blood samples inoculated with Candida cells which were pretreated by minibead beating to mechanically disrupt the cells, with the DNA extracted by either a previously described guanidium thiocyanate-silica method or the commercially available QIAmp tissue kit. PCR amplification of the extracted DNA and subsequent DNA probe hybridization in the LiPA assay yielded detection limits of 2 to 10 cells/ml. An internal standard control was included in the PCR amplification to monitor for PCR inhibition. This fungal PCR-LiPA assay is robust and sensitive and can easily be integrated into a clinical-testing laboratory with the potential for same-day diagnosis of fungal infection.

DNA Primers↗

Quantitation of CD8(+) T-lymphocyte responses to multiple epitopes from simian virus 40 (SV40) large T antigen in C57BL/6 mice immunized with SV40, SV40 T-antigen-transformed cells, or vaccinia virus recombinants expressing full-length T antigen or epitope minigenes.

The cytotoxic T-lymphocyte response to wild-type simian virus 40 large tumor antigen (Tag) in C57BL/6 (H2(b)) mice is directed against three H2-D(b)-restricted epitopes, I, II/III, and V, and one H2-K(b)-restricted epitope, IV. Epitopes I, II/III, and IV are immunodominant, while epitope V is immunorecessive. We investigated whether this hierarchical response was established in vivo or was due to differential expansion in vitro by using direct enumeration of CD8(+) T lymphocytes with Tag epitope/major histocompatibility complex class I tetramers and intracellular gamma interferon staining. The results demonstrate that epitope IV-specific CD8(+) T cells dominated the Tag-specific response in vivo following immunization with full-length Tag while CD8(+) T cells specific for epitopes I and II/III were detected at less than one-third of this level. The immunorecessive nature of epitope V was apparent in vivo, since epitope V-specific CD8(+) T cells were undetectable following immunization with full-length Tag. In contrast, high levels of epitope V-specific CD8(+) T lymphocytes were recruited in vivo following immunization and boosting with a Tag variant in which epitopes I, II/III, and IV had been inactivated. In addition, analysis of the T-cell receptor beta (TCRbeta) repertoire of Tag epitope-specific CD8(+) cells revealed that multiple TCRbeta variable regions were utilized for each epitope except Tag epitope II/III, which was limited to TCRbeta10 usage. These results indicate that the hierarchy of Tag epitope-specific CD8(+) T-cell responses is established in vivo.

Animals↗

Effects of chronic dietary exposure to genistein, a phytoestrogen, during various stages of development on reproductive hormones and spermatogenesis in rats.

Developmental, hormonal, and gametogenic parameters were evaluated in male progeny following chronic dietary exposure to the phytoestrogen genistein. Twenty pregnant rats were fed a diet containing genistein (50 microg/d) from d 17 of gestation, and 12 were fed a control diet without genistein. Four litters each of control and genistein-fed rats were euthanized on d 21. The remaining pups were weaned on d 21 and only male rats were used in this study. On d 21, eight litters of genistein-fed rats were placed on control diet (gestational and lactational exposure alone [GL-G]), and the remaining eight continued on genistein diet (lifelong exposure group [LL-G]). These rats were euthanized (four litters/group) on d 70 or 130 of life. Serum testosterone, which was slightly reduced in genistein-exposed rats on d 21, did not differ among treatment and control groups on d 70 and 130. Serum luteinizing hormone of genistein-exposed rats was reduced on d 21 and 130, but not on d 70. Serum follicle-stimulating hormone did not vary among groups at any age. Treatment-related effects of dietary genistein were not observed on the weights of the testes of 21-d-old rats. Except for a slight decrease in testis weight of GL-G rats at 130 d, no significant effect of dietary exposure was observed on the weight of the testes in any other group. However, epididymal weights were significantly reduced in both treated groups at d 130. Testicular sperm count (on d 70 as well as 130) also was not affected in GL-G or LL-G rats. We conclude that gestational plus lactational exposure to genistein and subsequent dietary exposure to genistein have no adverse effects on gametogenic function in male rats.

Aging↗

Plasma-volume contraction and exercise-induced hypoxaemia modulate erythropoietin production in healthy humans.

This study examined exercise-induced hypoxaemia (EIH) and plasma volume contraction as modulators of serum erythropoietin (Epo) production. Five athletes cycled for 3 min at supra-maximal power outputs, at each of two different elevations (1,000 m and 2,100 m). Five subjects were exposed to normobaric hypoxia (F(I)O(2)=0.159), seven subjects underwent plasmapheresis to reduce plasma volume and eight subjects were time controls for Epo levels. Oxyhaemoglobin saturation was significantly reduced during exercise and during normobaric hypoxia. The time period of haemoglobin oxygen saturation <91% was 24+/-29 s (mean+/-S.D., n=5) for exercise at 1000 m, 136+/-77 s (mean+/-S.D., n=5) for exercise at 2100 m and 178+/-255 s (mean+/-S.D., n=5) with resting hypoxic exposure. However, significantly increased serum Epo levels were observed only following exercise (24+/-3%; mean+/-S.D., n=5 at 1,000 m and 36+/-5%; mean+/-S.D., n=5 at 2,100 m). Volume contraction also resulted in increased serum Epo (35+/-6%; mean+/-S.D., n=7) in spite of a significant rise in haematocrit of 2.2%. Despite similar degrees of arterial desaturation, only the hypoxaemia induced by exercise was associated with an increase in serum Epo. This finding indicates that other factors, in addition to hypoxaemia, are important in modulating the production of Epo in response to exercise. Volume depletion in the absence of exercise resulted in increases in Epo levels that were comparable with those observed in response to exercise. The paradoxical responses of the increased haematocrit and the increase in Epo in subjects undergoing plasmapheresis suggests that plasma volume may also modulate the production of Epo.

Adult↗

A mathematical analysis of hemorheological changes during heart valve replacement.

BACKGROUND: This study was carried out to establish a mathematical model in order to assess blood trauma and hemorheology during cardiopulmonary bypass and heart valve replacement. METHODS: Ten factors which represented blood trauma and hemorheology were investigated in fourteen patients undergoing mechanical heart valve replacement. RESULTS: The results confirmed that red blood cell damage was mainly dependent on cardiopulmonary bypass time and hematocrit level. Platelet aggregation was influenced by platelet count, plasma fibrinogen and cardiopulmonary bypass time, the cases with aortic valve replacement resulting in more platelet activation than the mitral valve replacement (p<0.05). High shear blood viscosity was significantly influenced by hematocrit, plasma viscosity and red cell filterability, while low shear blood viscosity was significantly related to hematocrit, plasma viscosity and fibrinogen concentration, which represented 68.5% and 74.8% of hemorheologic changes due to blood trauma respectively. CONCLUSIONS: The relationship between blood trauma and hemorheologic changes was evaluated and the potential areas for improvements in cardiopulmonary bypass techniques in relation to mechanical heart valve implantation were identified. These areas of technical and pharmacological development must reduce changes in all the possible plasma components especially fibrinogen and also preserve platelets and red cells from damage.

Adolescent↗