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Biomedical subjects

R Graham

Publications and source records attributed to R Graham.

At least 73 records · Page 4Linked to original sources
PubMed1984

Effect of hypoxic hypoxia on systemic vasculature.

Effects of hypoxic hypoxia (HH) on cardiac output (CO), CO distribution, arterial and venous pressure-flow curves, vascular compliance, vascular time constant (tau), and resistance to venous return (RVR) were evaluated on six dogs. The vascular bed was isolated into four compartments depending on venous drainage: superior vena cava (SVC), splanchnic, renal and adrenal, and the remainder of the inferior vena cava (IVC). Low arterial O2 content and PO2 produced a threefold increase in CO at the same mean arterial pressure and a significant redistribution of CO to the SVC. Arterial pressure-flow curves decreased their slope (i.e., flow resistance) by a factor of two in the IVC and renal beds and by a factor of three in the splanchnic and SVC beds. Venous pressure-flow curves for the animal also decreased their slope significantly. HH causes a twofold increase in venous compliance and in mean venous pressure; tau did not change, but RVR halved. Seventy percent of the CO increase is explained by the increase in mean venous pressure and 30% by the reduction in RVR.

Acid-Base Equilibrium↗
PubMed1984

Adverse responses to local anaesthetics.

Progressive challenge was used to investigate twenty-seven patients with a history of an adverse response to local anaesthesia. True allergy was detected in only one patient. The method does not exclude reactions to additives and preservatives in local anaesthetics. If preservative-free local anaesthetics are used for subsequent exposure in patients with no response to progressive challenge, subsequent exposure is safe. The possibility that some of these patients may be reacting to preservatives in the solutions cannot be excluded by such testing. Where possible preservative-free local anaesthetic preparations should be used for subsequent anaesthesia.

Anaphylaxis↗
PubMed1983

A comparison of triclosan and chlorhexidine preparations with 60 per cent isopropyl alcohol for hygienic hand disinfection.

Four detergent preparations containing triclosan; two alcoholic products, containing triclosan and chlorhexidine respectively, and a detergent preparation containing chlorhexidine were compared with 60 per cent isopropyl alcohol following a single hand wash using Escherichia coli as the test organism. In vitro tests indicated that all had a high activity against hospital pathogens. The triclosan-containing preparations exhibited a significant pathogens. The triclosan-containing preparations exhibited a significant residual activity. Experiments in volunteers showed that 0.5 per cent alcoholic triclosan was significantly more effective than all other preparations tested. All the detergent preparations had an effect similar to that of 60 per cent isopropyl alcohol. None of the seven products evaluated was significantly less bactericidal than 60 per cent isopropyl alcohol.

1-Propanol↗
PubMed1983

Dopamine, dobutamine, and phentolamine effects on pulmonary vascular mechanics.

The pressure-flow (P-Q) relationship of the pulmonary vasculature, in an isolated canine lobe perfused under classical zone II conditions, can be characterized by a rectilinear segment at high flow, a curvilinear segment at low flow, and a pulmonary arterial pressure (Ppa) that exceeds alveolar pressure at zero flow. This demonstrates the presence of critical closure in the pulmonary vascular bed. Effects of drugs on pulmonary vascular resistance (PVR) must take the normal P-Q relationship into account. We examined the effect of dopamine (D) and dobutamine (DB), alone and in combination with phentolamine (P), on the slope of the rectilinear segment of the P-Q curve (equivalent to vascular conductance), the extrapolated Ppa intercept (Ppai), and the Ppa at zero flow (Ppaz). Low-dose D (0.4-0.8 mg) and DB (1.0-5.0 mg) did not significantly alter any parameter from control. Higher-dose D (1.2-6.8 mg) and DB (13-38 mg) decreased vascular conductance 32.3 +/- 12.1 (SE) to 50.45 +/- 5.6% (P less than 0.05), and P alone increased conductance 12.0 +/- 2.6% (P less than 0.01) from control with no significant effect on Ppai or Ppaz. The change in conductance with D and DB alone was abolished when either drug was given in combination with P. Ppaz and Ppai decreased significantly from control with DB in combination with P when no significant effect on vascular conductance was noted. The results suggest that lung vessels determining changes in flow resistance are pharmacologically distinct from those subserving critical closure in the pulmonary vascular bed.

Animals↗
PubMed1982

Critical closure in the canine pulmonary vasculature.

The vascular pressure-flow (P-Q) relationships in zone II (West et al.) were studied in isolated canine left lower lobes, in order to characterize the total resistance in the pulmonary vascular bed with respect to incremental or flow resistance and critical closure. At each of five levels of static lung inflation, the P-Q relationship was curvilinear at low flow and rectilinear at higher flows. The slope of the linear portion was not significantly different at alveolar pressures (PA) = 5, 7, or 9 cm H2O, but decreased significantly at PA = 11 and 15 cm H2O ((P less than 0.05), indicating an increase in flow resistance. The pulmonary artery pressure (Ppa) fell to the same value at zero flow regardless of inflation level [10.1 +/- 1.0 (SD) cm H2O at PA = 5 cm H2O to 10.9 +/- 2.7 (SD) at PA = 15 cm H2O]. The Ppa intercept (Ppai), extrapolated from the linear portion of the P-Q curve and representing the average closing pressure for the vascular bed, increased from 16.0 +/- 1.8 (SD) cm H2O at PA = 5.0 to 26.5 +/- 4.4 (SD) cm H2O at PA = 15 (P less than 0.05) in a direct one-to-one relationship with the increase in PA. Since this results in a constant transmural gradient at the alveolar vessel level, these vessels must be the major fraction which undergo critical closure. Operationally defined vascular compliance, determined from the slope of a simultaneously obtained pressure-volume (P-V) curve, decreased significantly from 1.51 +/- 0.62 (SD) ml/cm H2O at PA = 5.0 H2O to 0.87 +/- 0.27 ml/cm H2O at PA = 15 cm H2O (P less than 0.05).

Animals↗
PubMed1981

Immunoglobulin localization in benign and malignant lesions of the human mammary gland.

Using direct imunofluorescence, lesions from 266 human breast specimens were studied for the presence of IgA, IgM, or IgG localization. The lesions included benign elements from 66 subcutaneous mastectomy specimens in which the absence of simultaneous breast malignancy was documented, primary breast carcinomas from 153 mastectomy specimens, and 47 biopsies containing metastatic breast cancer. A statistically significant association of IgA and IgM with benign lesions was contrasted to the association of IgG with malignant lesions. In both primary and metastatic lesions, IgG localization was associated with estrogen-receptor-poor primary cancers as compared with estrogen-receptor-rich primary cancers. Among primary breast cancer patients, IgG localization in the tumor correlated with relative lymphopenia. A shorter disease-free interval was noted in association with IgG localization among the metastatic breast lesions. No statistically significant association between stage of disease and immunoglobulin presence was demonstrable. Moderate-to-severe intraductal epithelial hyperplasias were more often associated with immunoglobulin G localization that were other benign lesions.

Adult↗
PubMed1981

Production of freeze-dried human antihaemophilic cryoprecipitate.

Concentration of factor VIII from fresh plasma by cryoprecipitation remains the basis for preparation of products used to treat haemophilia A. This paper describes the preparation of a factor VIII concentrate from small plasma pools in transfusion centres with drying facilities. The dried concentrate from one litre of plasma dissolves very well in 50 or 100 ml of distilled water and contains around 500 IU per bottle. The specific activity per mg protein is 0.19 IU and the fibrinogen concentration is half that in frozen cryoprecipitate. This method of drying causes no appreciable loss in the factor VIIIC activity and little denaturation as shown by the factor-VIII-related antigen/factor VIIIC ratio of 1.7.

Chemical Precipitation↗
PubMed1981

Identification of foreign matter in foods.

It is the purpose of this paper to review and illustrate recent, pertinent, advances in detection methods for those food particle contaminants that have potential as hazards to human health or that elevate the risk for product liability disputes. Sources for the contamination of the human food supply include extraneous particulates associated with raw materials, food handling and packaging processes, as well as extraneous filth from insects and rodents. Likewise, environmental particulates, either airborne or in liquid suspension, can be considered as potential food contaminants. Concern for the quality of human foods relates to the type and quantity of suspected contaminants. To reduce the risk of particle contaminations of all types in human food supplies and to insure high yields of safe, high quality products, industry safeguards include monitoring and identification of foreign matter. Supportive methodology has been developed to detect, separate and identify particle contaminants of many types. Microscopic contaminants are characterized using light microscopy, electron microscopy and allied techniques. Specific applications of these techniques are described in brief detail.

Asbestos↗
PubMed1980

Public policy implications of graduate follow-up studies in family practice.

An assessment of the progress of family practice over the last ten years, from the point of view of public policy analysis, finds that family practice has adequately and successfully addressed the majority of the policy issues of concern to its major constituencies in the early 1970s. The decade of the 1980s finds family practice as a vigorous, thriving specialty, which has met many of the early expectations of its supporters. Now, however, because of its own growth and the changing environment of medical practice in the United States, family practice faces a broad range of expectations and policy challenges from a wider, and in some cases more hostile, constituency.

Family Practice↗
PubMed1979

Isolation of an iron-binding compound from Pseudomonas aeruginosa.

An iron-binding compound was isolated from ethyl acetate extracts of culture supernatant fluids of Pseudomonas aeruginosa and was purified by successive paper and thin-layer chromatographic procedures. The purified compound was characterized by UV, visible, infrared, and fluorescence spectroscopy. The compound possesses phenolic characteristics, with little or no similarity to dihydroxybenzoates and no indication of a hydroxamate group. P. aeruginosa synthesized the compound during active growth in culture media containing less than 5 X 10(-6) M added FeCl3. When added to iron-poor cultures of P. aeruginosa, the compound promoted the growth of the bacterium and also reversed growth inhibition by the iron chelator ethylenediamine-di-(o-hydroxyphenylacetic acid).

Ethylenediamines↗
PubMed1978

Observations of the effects of formaldehyde on cockroaches and their flora: III. The effect of formaldehyde in eliminating the normal gut flora.

The normal flora of cockroaches (Periplaneta americana) was determined over a period of 24 days prior to substituting water with 1% Formalin for drinking water. During the first 4 days of treatment the normal flora was significantly reduced and by the fifth day, when the cockroaches became diarrhoeic, no bacteria, fungi, or viruses could be detected by the methods used.

Animals↗