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Biomedical subjects

G Cook

Publications and source records attributed to G Cook.

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

Intracranial imaging.

This article concentrates on the imaging of intracranial structures and outlines some basic imaging strategies for common clinical presentations.

Acute Disease↗
PubMed1996

Microleakage of composite resin restorations with a 10 percent maleic acid etchant.

Microleakage of Class V composite resin restorations with margins all in enamel were compared in this in-vitro study using Scotchbond MultiPurpose Adhesive (SMP) (3M Corp.), and Scotchbond II (SB II) (3M Corp). Twenty extracted human molars were randomly separated into two groups: Group One, which used the SMP system and Group Two, which used the SB II system. Circular Class V preparations were cut 1.8 mm deep and 3 mm in diameter using a #556 fissure bur. Cavosurface margins, all in enamel, were beveled. The enamel and dentin were treated following manufacturer's directions for each group, and a microfilled composite resin, Silux Plus (3M Corp), was applied in two hand-placed increments. All teeth were finished with Sof-Lex discs, stored in water for seven days, then thermocycled in a water bath for 100 cycles, alternating from 4 degrees C to 58 degrees C. The teeth were placed in a 5 percent solution of methylene blue, rinsed and then invested in resin. All teeth were sectioned vertically and horizontally and a ratio (percentage) of wall length to amount of leakage along each wall was established. The overall mean leakage of Group One was 15.27 percent and Group Two was 13.84 percent. Looking at individual walls, the mean occlusal wall leakage of Group One was 28.41 percent and Group Two was 12.45 percent. Mean gingival wall leakage of Group One was 15.96 percent and Group Two was 21.80 percent. Comparing the two groups, using a student's t test, there was no significant difference between the overall mean leakage or between the gingival wall leakage (p > 0.05); however, there was a significant difference between the occlusal wall leakage (p < 0.05), with SMP exhibiting more leakage.

Acid Etching, Dental↗
PubMed1995

Feeling the parts: a developmental study of separable perception with tactile dimensions.

A tetrad classification task was used to determine perceptual sensitivity to the tactile dimensions of texture, hardness, and shape in 5- and 11-year-old children who classified objects by touch, unaided by vision. Both age groups reliably used separate dimensions to group the objects. Both age-related and individual differences in dimensional salience were observed. Five-year-olds predominantly grouped objects that were identical in hardness; 11-year-olds most often grouped objects identical in hardness or shape. Overall (integral) similarity was not used reliably by any participant. Results support the differential-sensitivity view of cognitive development and are consistent with Garner's (1970) distinction between integral and separable stimulus structure, but they do not support the hypothesized developmental trend from integral to separable perception.

Age Factors↗
PubMed1995

Comparative assessment of small intestinal and colonic permeability in HIV-infected homosexual men.

OBJECTIVES: To investigate both small and large intestinal permeability in HIV-positive subjects, and correlate variation in intestinal mucosal abnormality with immunological and nutritional markers of HIV disease. METHODS: Small and large intestinal permeability studies were performed in 14 HIV-seropositive patients and eight healthy men. Eight out of the 14 patients had diarrhoea and all subjects were negative for enteropathogens. Small intestinal permeability was determined using the lactulose-mannitol test and large intestinal permeability using the colonic absorption of 51Cr-EDTA. In addition, CD4 cell count, beta 2-microglobulin, C-reactive protein estimation and anthropometry were carried out in all subjects. RESULTS: HIV-seropositive subjects had higher lactulose-mannitol ratios (LMR; 0.084 +/- 0.007 versus 0.013 +/- 0.0008) and lower 51Cr activity (1.986 +/- 0.066 versus 3.115 +/- 0.560) than controls (P < 0.0004 and P < 0.05, respectively). Colonic uptake of 51Cr-EDTA was no different between subjects with and those without diarrhoea (2.04 +/- 0.124 versus 1.92 +/- 0.143, P > 0.05). A negative correlation was found between LMR and 51Cr-EDTA, but only for patients with diarrhoea (r = -0.81; P = 0.015). CONCLUSION: Regional variation affecting intestinal absorptive function occurs in patients with HIV-related diarrhoea and is characterized by increased LMR and reduced colonic uptake of 51Cr-EDTA. The pathogenesis and clinical significance of such changes are unknown.

AIDS-Related Opportunistic Infections↗
PubMed1995

Phase II trial of docetaxel in advanced anthracycline-resistant or anthracenedione-resistant breast cancer.

PURPOSE: The purpose of this study was to evaluate the clinical efficacy and safety of docetaxel in patients with metastatic breast cancer (MBC) resistant to doxorubicin or mitoxantrone. PATIENTS AND METHODS: Docetaxel 100 mg/m2 was administered as a 1-hour intravenous (IV) infusion every 3 weeks to 42 patients registered at four centers. Patients must have received at least one but no more than two prior chemotherapy regimens for MBC (in addition to any prior adjuvant therapy). One of the regimens for metastatic breast cancer must have included an anthracycline or anthracenedione and the cancer must have progressed on that regimen. RESULTS: Objective responses were seen in 20 of 35 assessable patients (three complete responses [CRs] and 17 partial responses [PRs]), for an objective response rate of 57% (95% confidence interval [CI], 39% to 74%) and in 21 of 42 registered patients (50% response rate [RR]; 95% CI, 34% to 66%) entered onto the trial. The median response duration was 28 weeks. The most common toxicity in this study was grade 4 neutropenia, which occurred in 95% of patients. Other clinically significant nonhematologic side effects included stomatitis, skin reactions, neurosensory changes, asthenia, and fluid retention. Patients who received dexamethasone premedication had a later onset of fluid retention than those who did not receive dexamethasone (onset at a median cumulative docetaxel dose of 503 mg/m2 and 291 mg/m2, respectively). CONCLUSION: Docetaxel at this dose and schedule has a high level of antitumor activity in patients with treatment-refractory advanced breast cancer, and appears to be one of the most active agents for the treatment of this patient population.

Adult↗
PubMed1995

Case report: renal transplant artery stenosis--three cases where magnetic resonance angiography was superior to conventional arteriography.

Stenosis of renal transplant arteries is a common cause of graft dysfunction and hypertension. Conventionally it is investigated by intraarterial digital subtraction angiography (IA DSA). Recently three-dimensional phase contrast magnetic resonance angiography (MRA) has been used successfully as a non-invasive method of assessing renal transplant arteries. We report three cases where MRA was superior to IA DSA in the detection of renal transplant artery stenosis.

Adult↗
PubMed1995

The priority of separable perception in stimulus classifications of children with mental retardation.

Children (mean CA = 12 years) with mental retardation and adults without mental retardation classified tetrads of stimuli that could be grouped according to identities on separate dimensions or according to overall similarity. When color, size, and line orientation were varied (Experiment 1), both groups used separate dimensions for classification. When hue, saturation, and brightness varied (Experiment 2), both groups used overall similarity for classification. Test-retest correlations showed that the predominant classifications were reliable across 1-week testing intervals. Results support Garner's distinction between separable and integral stimulus structure but do not support an integral-to-separable shift in perceptual development. Comparisons of the tetrad task used in the present study and triads used in previous work are discussed as well as implications of the present data for developmental theories of perceptual classification and processing in children with mental retardation.

Adolescent↗
PubMed1995

Acute cutaneous reactions to docetaxel, a new chemotherapeutic agent.

BACKGROUND: Docetaxel (RP 56976) is a new chemotherapeutic agent that has shown promise in a number of animal studies and is currently undergoing phase I and phase II trials. Early in the phase I trials, it was noted that a significant number of patients were experiencing a variety of cutaneous complaints, so we elected to prospectively evaluate the cutaneous reactions occurring during the first three courses of therapy in the first 12 patients enrolled for phase I chemotherapy at our institutions. OBSERVATIONS: All but one patient had some type of cutaneous eruption over the three courses of therapy. Of the 27 evaluable courses of docetaxel given, 19 (70%) resulted in a cutaneous eruption with four (21%) being asymptomatic and 15 (79%) being at least mildly symptomatic. The most common reaction seen was characterized by discrete erythematous to violaceous patches or edematous plaques similar to acral erythema. CONCLUSION: Although a majority of patients receiving docetaxel experience some degree of cutaneous reaction, the eruptions are usually mildly symptomatic and almost always self-limiting.

Acute Disease↗
PubMed1994

Familial thrombophilia and activated protein C resistance: thrombotic risk in pregnancy?

An abnormal anticoagulant response in vitro to activated protein C (aPC) has been proposed as an aetiological factor in familial thrombophilia. It is postulated that this phenomenon is due to an inherited molecular defect of factor V resulting in poor inactivation by aPC. We conducted a family study when the proband presented in her second pregnancy with superficial phlebitis, a history of deep venous thrombosis and a family history of venous thromboembolic disease. No abnormality of antithrombin activity, protein C activity or deficiency of protein S were demonstrated in the family members tested. The proband had aPC ratios below the laboratory range on three consecutive occasions. In addition, her mother, who had a history of recurrent DVTs and a pulmonary embolus, and also an asymptomatic nulliparous sister, both had aPC resistance ratios below the laboratory range on consecutive samples. Further information about the combined risk of aPC resistance and pregnancy is needed before guidance on the management of affected women can be formulated.

Adult↗
PubMed1994

Petrol octane booster and methaemoglobinaemia.

We highlight the case of a 35-year-old male who suffered a respiratory arrest as a result of methaemoglobinaemia secondary to skin contamination and inhalation of petrol octane booster following a road traffic accident. It is important that petrol octane booster is stored safely in leak-proof containers and that suitable warnings are displayed to alert the user of potential toxicity.

Adult↗
PubMed1993

Substance P modulates antigen-induced, IFN-gamma production in murine Schistosomiasis mansoni.

In murine Schistosomiasis mansoni, granuloma eosinophils make SP. We investigated whether SP affects lymphokine secretion in murine schistosomiasis. SP at > or = 10(-10) M, and other tachykinins at much higher concentrations, substantially increased IFN-gamma secretion from spleen or granuloma inflammatory cells primed in vitro by suboptimal stimulatory concentrations of egg Ag or mitogen. Cells receiving maximal antigenic or mitogenic stimulation were affected marginally. Also, tachykinins induced no IFN-gamma from resting cells receiving no Ag or mitogen stimulation. There are three distinct tachykinin receptors, called NK-1, NK-2 and NK-3. SP binds the NK-1 receptor with highest affinity. Specific NK-1 receptor antagonists blocked all tachykinin-induced, IFN-gamma secretion. An NK-2 receptor inhibitor had no effect. Thus, SP and other tachykinins were acting through an NK-1 receptor. Inflammatory cells from 4-day-old granulomas cultured in vitro secrete IFN-gamma. Yet, there was no measurable IFN-gamma when SP receptor antagonists were added to the cultures. Moreover, animals treated in vivo with the NK-1 receptor antagonist CP-96,345 produced smaller granulomas. This suggested that endogenous SP may be necessary for normal induction of granuloma IFN-gamma secretion and a normal granulomatous response. Granuloma macrophages make somatostatin (SOM) that can decrease IFN-gamma secretion. Yet, IFN-gamma secretion was unaffected when both SP and SOM were in the cell cultures. In conclusion, SP modulates Ag-driven IFN-gamma secretion through a NK-1 receptor. Also, SP and SOM may be components of a natural circuit within inflammation that regulates IFN-gamma production.

Animals↗
PubMed1993

In vivo sucrase-isomaltase and lactase-phlorizin hydrolase turnover in the fed adult rat.

We estimated in vivo turnover rates of sucrase-isomaltase and lactase-phlorizin hydrolase in adult rats. Fed animals received a primed continuous infusion of phenylalanine (300 microCi, 150 mumol Phe/100 g of body weight for 30 s, then 7.5 microCi, 3.75 mumol Phe/min for 10 to 140 min). Sucrase-isomaltase and lactase-phlorizin hydrolase were immunoprecipitated from jejunal mucosal membranes; isoforms were separated by SDS-polyacrylamide gel electrophoresis. Endoglycosidase H digestions and (for lactase-phlorizin hydrolase) N-terminal amino acid sequencing were performed on all isoforms. Specific radioactivity of prosucrase-isomaltase and prolactase-phlorizin hydrolase isoforms reached isotopic equilibrium by 60 and 90 min, respectively. Specific radioactivity of brush border sucrase and lactase did not reach steady state. The isotope kinetic, N-terminal amino acid sequencing, and endoglycosidase H digestion data suggested that one of the high molecular weight lactase isoforms is a dimer of mature lactase. Compartmental modeling of specific radioactivity demonstrated that mean intracellular residence time is 59 min for prosucrase-isomaltase isoforms and 68 min for prolactase-phlorizin hydrolase isoforms. Mean residence time in the brush border was 5.8 h for sucrase and 7.8 h for lactase. Fractional synthesis rates were 414%/day for sucrase and 307%/day for lactase. Thus, in vivo brush border sucrase and lactase turn over at similar rates in the adult rat.

Amino Acid Sequence↗
PubMed1993

Anxiolytic-like and antinociceptive effects of MK-801 accompanied by sedation and ataxia in primates.

Anxiolytic-like and antinociceptive activities of the noncompetitive NMDA receptor antagonist MK-801 (dizocilpine) were compared with sedative and ataxic side effects in primates. Administration of MK-801 (0.1 mg/kg) caused taming in cynomolgus monkeys and increased tail withdrawal latencies in squirrel monkeys; both effects were accompanied by sedation and ataxia. These findings are discussed in relation to the possible therapeutic uses of NMDA antagonists and differences in the behavioural effects of such compounds in primate and rodent species.

Analgesics↗
PubMed1993

Antinociceptive activity of NK1 receptor antagonists: non-specific effects of racemic RP67580.

1. Release of substance P in the dorsal horn is considered a primary event in the perception of pain. The profile of racemic RP67580, a non-peptide antagonist at the NK1 (substance P) receptor, was examined in a range of antinociception tests on rodents. 2. At doses up to 30 mg kg-1, s.c. racemic RP67580 exhibited antinociceptive activity in writhing and formalin paw tests in mice and gerbils. Acetic acid induced writhing and the licking response to formalin were reduced to 40-50% of the level observed in vehicle-treated animals (P < 0.05). However, this agent was not active in mouse tail flick, rat paw pressure or rat and guinea-pig formalin paw tests. 3. Like racemic RP67580, the calcium channel blockers nifedipine (30 mg kg-1, i.p.) and verapamil (10 or 20 mg kg-1, s.c.) inhibited the response to formalin by approximately 60% in gerbils (P < 0.05 compared with vehicle-treated animals). 4. Evidence for calcium channel antagonist activity of RP67580 was obtained in vitro. Racemic RP67580 inhibited calcium entry into depolarized strips of guinea-pig ileum longitudinal muscle myenteric plexus (apparent KB = 587 +/- 115 nM), inhibited [3H]-diltiazem binding to rabbit skeletal membranes (IC50 = 298 nM) and depressed high threshold calcium currents in neurones cultured from rat cortex (10% inhibition at 10 microM). 5. These findings indicate that the acute antinociceptive effects of RP67580 may not be attributable to a specific interaction with NK1 receptors and may be mediated via calcium channel blockade.

Analgesics↗