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Biomedical subjects

D Craig

Publications and source records attributed to D Craig.

At least 55 records · Page 3Linked to original sources
PubMed1996

Modeling and mutagenesis of the human alpha 1a-adrenoceptor: orientation and function of transmembrane helix V sidechains.

A 3-dimensional model of the seven transmembrane helical segments (TMs) of the human alpha 1a-adrenoceptor was initially built by analogy to the known structure of bacteriorhodopsin. However, the rotational orientation of TM V about its helical axis, and the roles of several TM V residues in ligand binding and receptor activation remained in question. Accordingly, we determined the effects of six site-specific mutations in TM V on binding affinity and functional potency of a structurally diverse series of agonists and antagonists. Mutation of Ser 192 and Phe 193 disrupted the binding of many of the tested ligands, as measured by displacement of [3H]prazosin. In addition, mutation of Ser 188, Ser 192, and Phe 193 disrupted receptor activation, as measured by [3H]inositol phosphate formation. On the basis of these results, a specific rotational orientation of TM V is proposed as part of a revised receptor model, which also takes into account more recently reported information about the structure of rhodopsin. This revised alpha 1a-adrenoceptor model accounts for direct interactions which are proposed between Ser 188 and Ser 192 and the meta and para hydroxyl groups of norepinephrine, respectively, in the G-protein coupled receptor state.

Amino Acid Sequence↗
PubMed1995

Fluorescence-based enzymatic assay by capillary electrophoresis laser-induced fluorescence detection for the determination of a few beta-galactosidase molecules.

beta-Galactosidase can be assayed by monitoring the generation of the fluorescent products, fluorescein-mono-beta-D-galactopyranoside and fluorescein, when the fluorogenic substrate fluorescein-di-beta-D-galactopyranoside is used. We have used capillary electrophoresis with ultrasensitive laser-induced fluorescence detection to monitor the formation of the fluorescent products of off-column enzymatic reactions. By analyzing as little as 40 pl of the enzymatic mixture we obtain limits of detection of 6.5 x 10(-14) M beta-galactosidase or 1.6 molecules based on the detection of fluorescein-mono-beta-D-galactopyranoside.

Electrophoresis↗
PubMed1995

The effects of brain death on cardiopulmonary hemodynamics and pulmonary blood flow characteristics.

Deterioration of donor lung function contributes to the shortage of donor organs and early postoperative failure after transplantation. A decrease in donor pulmonary function is associated with opacification of lung fields on radiographs, rendering the lungs unsuitable for transplantation, which may be related to the effects of brain death (BD) on pulmonary hemodynamics. Twenty mongrel canines (25.5 +/- 0.7 kg) underwent 20 BD experiments using a previously validated BD organ donor model. An ultrasonic flowmeter was applied on the pulmonary artery and micromanometers were inserted into the right ventricle, pulmonary artery, and left atrium to measure, which allowed the hemodynamic assessment and impedance profile analysis of the pulmonary vasculature by Fourier transformation. Characteristic impedance (Zo) was compared with input resistance (RIN) and with calculated pulmonary vascular resistance (PVR), the conventional index. Right ventricular hydraulic power was analyzed and divided in its components oscillatory and steady power. The results are expressed as means and SEM (analysis of variance, paired two-tailed t tests). Cushing reflex, hemodynamic response, and diabetes insipidus were consistent findings following BD. PVR, Zo, and RIN decreased significantly (p < 0.05) from 367 +/- 40 dyne.s.cm-5, 226 +/- 13 dyne.s.cm-5, and 771 +/- 52 dyne.s.cm-5 to 261 +/- 25 dyne.s.cm-5, 159 +/- 10 dyne.s.cm-5, and 651 +/- 69 dyne.s.cm-5 6 h after BD. Pulmonary artery blood flow increased significantly from 1,499 +/- 107 mL/min to 2,064 +/- 209 mL/min (p < 0.05) after BD. Hydraulic power increased from 69 +/- 6 mW to 104 +/- 13 mW (p < 0.05) and the oscillatory power to steady power ratio of 33%/67% changed to 23%/77% following BD. Extravascular pulmonary water content increased significantly by 10% after BD. BD causes a significant change in pulmonary vascular hemodynamics. The decrease in impedance and right ventricular afterload may lead to significant pulmonary overflow injury and edema. The increase in steady power represents an important reserve of the right ventricle to sustain pulmonary blood flow following BD.

Animals↗
PubMed1994

Evaluation of involuntary weight loss. Where do you start?

When a patient presents with involuntary weight loss, the etiologic considerations can be overwhelming. To plan a cost-effective workup, physicians need to be aware of the most common causes of weight loss and the tests that yield the most pertinent data. Drs Wise and Craig review the clinical studies on unintentional weight loss and suggest an initial approach to management.

Aged↗
PubMed1993

Adolescents' cognitions and attributions for academic cheating: a cross-national study.

We examined perceptions about academic cheating in comparable 11th-grade students from Costa Rica, Germany, and the United States to assess the similarities and differences associated with the different societies, with achievement status, and with gender. German students generally differed substantially from both Costa Rican and U.S. students in perceptions of the problem, critical attributes of cheating, causes of cheating, and beliefs about effective ways to control cheating in the school. We did find some important similarities across all three samples, however. Achievement and gender effects were less substantial but were uniform across the three groups.

Adolescent↗
PubMed1993

Bone-graft reconstruction of the monkey orbital floor with iliac grafts and titanium mesh plates: a histometric study.

Bone-graft reconstruction of large orbital defects has been difficult because of a lack of marginal support of the grafts and unpredictable resorption. A titanium mesh orbital plate has been developed to provide this marginal support for bone grafts. However, the problem of unpredictable bone-graft resorption remains. To determine if this plate has any effect on graft resorption, this study was designed to quantitate the dimensions and composition of bone autografts (1) with and without titanium plate support and (2) in the anterior and posterior orbit. Bilateral full-thickness large orbital floor defects were surgically created in five monkeys, and a titanium orbital floor plate was fixed with screws into the right orbit. Two iliac crest grafts were measured and placed transversely and without fixation in each orbit, one anterior and the other posterior to the axis of the globe. The orbits were retrieved 28 weeks after surgery and were analyzed histologically and histometrically. Comparison of the supported and nonsupported grafts revealed no differences in their histologic appearance. There were three significant histometric findings: (1) resorption of bone was similar for those grafts which spanned an orbital floor defect and those which were supported by a titanium plate; (2) resorption of grafts in the posterior orbit did not differ from that of grafts in the anterior orbit; and (3) resorption of approximately one-third of bone-graft thickness and width had taken place during the 28-week study interval. We conclude that the benefits of bone-graft support by a titanium mesh orbital floor plate are not offset by any alteration in bone-graft resorption.

Animals↗
PubMed1992

Plasmid cDNA-directed protein synthesis in a coupled eukaryotic in vitro transcription-translation system.

A system is described in which transcription of cDNA clones by bacteriophage T7 RNA polymerase is coupled to translation in the micrococcal nuclease treated rabbit reticulocyte lysate in a single reaction of coupled transcription-translation. The monovalent and divalent cation requirements for translation are dominant for optimum expression in this coupled system, so that transcription is relatively inefficient. Nevertheless, the use of appropriate DNA concentrations leads to the synthesis of sufficient RNA to saturate the protein synthesis capacity of the system. The fidelity and efficiency of expression in this coupled system are high, and the degree of purification of the plasmid DNA is relatively uncritical. The system therefore offers very considerable advantages for rapid screening of 'mini-preparations' of cDNA plasmid constructs for retention of the correct reading frame and expression of the desired protein product.

Animals↗