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Biomedical subjects

G Reed

Publications and source records attributed to G Reed.

At least 19 recordsLinked to original sources
PubMed1995

Cholinergic regulation of neurite outgrowth from isolated chick sympathetic neurons in culture.

Neurotransmitters have been reported to regulate neurite outgrowth in several vertebrate and nonvertebrate species. In this study, cultures of isolated embryonic day 12 (E12) chick sympathetic neurons were grown in the presence of cholinergic receptor agonists or antagonists. Both ACh and the nonhydrolyzable cholinergic agonist carbamylcholine (CCh) inhibited neurite outgrowth. ACh (0.1-1.0 mM) decreased the percentage of neurons bearing neurites, but had no significant effect on cell survival. The effect of ACh was increased in the presence of the cholinesterase inhibitors BW284C51 (1 microM), Tacrine (20 microM), and edrophonium (200 microM). Neurite outgrowth was strongly inhibited by the muscarinic receptor agonist oxotremorine (5-100 microM) and weakly inhibited by nicotine (50 nM to 10 microM). The inhibitory effect of CCh was decreased by the muscarinic receptor antagonist atropine (10 microM), demonstrating that the effect of CCh on neurite outgrowth was mediated, at least in part, through a muscarinic receptor. The possibility that AChE can influence neurite outgrowth directly, through a noncatalytic mechanism, was also examined. When dissociated chick brain or sympathetic neurons were grown on plates precoated with purified AChE, neurite outgrowth was strongly stimulated. However, the neurite outgrowth-promoting effect of AChE was strictly dependent upon the presence of substratum-bound heparan sulfate proteoglycans (HSPG). Pretreatment of AChE with diisopropylfluorophosphate to inhibit the esterase activity did not abolish this effect, suggesting that the neurite outgrowth-promoting effect of AChE was associated with a noncatalytic mechanism, a view supported by the observation that soluble AChE had no effect on neurite outgrowth.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1994

Attenuation of monochromatic X-rays by normal and abnormal breast tissues.

RATIONALE AND OBJECTIVES: A prior study indicated that differences in the x-ray linear attenuation coefficients of cancerous and normal breast tissues tend to increase as the energy of the incident beam decreases. The authors investigated x-ray energies down to 20 keV. In the current study, the linear attenuation coefficients for normal and selected cancerous breast tissues within the energy range of 14 to 18 keV were determined. METHODS: Fifty breast biopsy specimens consisting of a mixture of breast malignancies, normal tissues, fat specimens, and tumors grown in rats were used. X-ray linear attenuation coefficients were measured for each sample within the energy range of 14.15 to 18 keV, using monoenergetic x-rays from beamline X-19A at the National Synchrotron Light Source at Brookhaven National Laboratory. Each sample was measured at 130 different energies starting at 14.15 keV with step sizes of 0.030 keV. Correlation of the measured attenuation coefficients for cellular makeup was performed. RESULTS: The mean of linear attenuation coefficients for samples classified as "cancers" was 10.9% higher than the mean of samples classified as "normal" breast tissues and was 66.5% higher than the mean of samples classified as normal breast fat. CONCLUSIONS: Differences in the linear attenuation coefficients of monochromatic x-rays between 14.15 and 18 keV do exist between normal and cancerous tissues, but there is some degree of overlap.

Biopsy↗
PubMed1994

Fundholders' referral patterns and perceptions of service quality in hospital provision of elective general surgery.

BACKGROUND: The introduction of fundholding established an internal market in public sector health care, involving purchasers and providers contracting for the supply of health care. AIM: This study set out to examine fundholders' hospital referral patterns, and to evaluate the quality of the service provided to patients undergoing elective general surgery, as perceived by fundholding general practitioners. METHOD: A questionnaire was posted to the senior partners of all fundholding practices in the Trent Regional Health Authority area. This questionnaire requested assessments of the importance of 13 specified aspects of service quality and the quality of provision by general practitioners' most frequently-used hospitals. Five-point scales were employed in each case. Respondents were asked to provide additional details about their practice. RESULTS: A 67% response rate was achieved. Confidence in the consultant's ability, short waiting times and informative feedback from the providers emerged as the most important elements in referral decisions, while the cost of treatment and patient convenience received lower importance ratings. In terms of how well their providers were seen to perform, fundholders ranked confidence in the consultant and patient convenience highest, and style of hospital management lowest. The majority of referrals seemed to be local. CONCLUSION: Judged in terms of fundholders' perceptions, sizeable variations in service quality between hospital providers of general surgery are evident.

Elective Surgical Procedures↗
PubMed1994

A heparin-binding domain in the amyloid protein precursor of Alzheimer's disease is involved in the regulation of neurite outgrowth.

The amyloid protein precursor (APP) of Alzheimer's disease is synthesized as an integral transmembrane protein that is released from cells in culture following proteolytic cleavage. The function of released APP is not known, although there is evidence that the protein may bind to components of the extracellular matrix (ECM). In the present study, substratum-bound APP stimulated neurite outgrowth in cultures of chick sympathetic and mouse hippocampal neurons. This effect was dependent upon the presence of substratum-bound heparan sulfate proteoglycans (HSPG). The effect of APP on neurite outgrowth was comparable to that of laminin. A 14 K N-terminal fragment of APP was found to bind heparin and a region close to the N-terminus of APP (residues 96-110) identified as a potential heparin-binding domain based on secondary structure predictions and molecular modeling. Mutagenesis of three basic residues (lysine-99, arginine-100, and arginine-102) resulted in a recombinant protein (APPhep) with decreased heparin-binding capacity. A peptide homologous to the heparin-binding domain was synthesized and found to bind strongly to heparin and to inhibit binding of 125I-labeled APP to heparin (IC50 approximately 10(-7) M). The peptide blocked the effect of APP on neurite outgrowth (IC50 approximately 10(-7) M), whereas two other peptides homologous to other domains in APP had no effect. The results indicate that the binding of APP to HSPG in the ECM may stimulate the effects of APP on neurite outgrowth.

Amino Acid Sequence↗
PubMed1993

Comparison of monovalent and trivalent live attenuated influenza vaccines in young children.

Fifty children, 6 months to 2 years of age, were vaccinated intranasally with a trivalent preparation containing 10(6) TCID50 each of H1N1 and H3N2 and 10(4) (n = 14) or 10(6) (n = 36) TCID50 of B live, attenuated, cold-adapted (ca) influenza strains. The same doses were administered as monovalent vaccines to 69 comparably aged children. Forty-five controls were given placebo. No clinically significant adverse reactions to vaccines were observed. Of children seronegative to H1N1 or H3N2, > or = 90% were infected by these vaccine strains. Trivalent vaccine containing 10(4) TCID50 of B infected only 27% of children seronegative to B (3/11), which was markedly reduced from the 88% infection rate (7/8) following monovalent B vaccine of the same dose (P = .02); increasing the B dose to 10(6) TCID50 increased the infection rate to 81% (21/26). Replication of ca influenza viruses in tissue culture matched vaccine responses. Trivalent ca influenza vaccines can be formulated that are safe and immunogenic in young children.

Animals↗
PubMed1992

Murine model of cutaneous infection with gram-positive cocci.

Staphylococcus aureus has remained an important cause of nosocomial wound infections, but standardized or reproducible systems for analyzing cutaneous infections caused by S. aureus do not exist. A variety of foreign materials, variable inocula, and skin traumas have been used to promote infection. To minimize these variables and ensure reproducibility, we chose a model using subcutaneous injections of a fixed quantity of dextran microbeads (Cytodex) as the foreign material added to standardized broth suspensions of S. aureus. Suspensions (0.2 ml) injected into an outbred strain of immunocompetent hairless mice generated reproducible, measurable lesions. With S. aureus Smith Diffuse, fluctuant, erythematous lesions with a peak diameter of 15 mm were observed; these lesions yielded purulent material containing gram-positive cocci and neutrophils and yielded growth of S. aureus on culture. Lesion size was proportional to the bacterial inoculum size. Histologic examination of excised lesions revealed typical abscesses. A second strain of S. aureus (SLC3) produced dermonecrosis instead of abscesses at an inoculum size of 10(7) CFU. Control injections with a sterile Cytodex suspension regularly produced nondraining, nonerythematous nodules with maximum diameters of less than or equal to 5 mm. Streptococcus pyogenes produced late-onset necrotic lesions and abscesses. Using a foreign substance, this model generates easily observed and reproducible cutaneous infection with S. aureus and streptococci that can potentially discriminate between inter- and intrastrain differences. Such a model could be used to test the pathogenicity of isogeneic strains of these bacterial species and to evaluate the efficacy of antimicrobial agents.

Analysis of Variance↗
PubMed1992

A study of osteoporosis as it relates to metabolic manifestations in edentulous women.

Among some patients, regardless of age, the jaw loses bone mass, leading to loosening and falling out of otherwise healthy teeth. This study seeks to establish whether this bone loss is associated with the metabolic manifestations of other forms of localized decalcifications, such as in Paget's disease, or with generalized osteoporosis. Sixteen women being fitted with dental implants to compensate for bone losses provided 24-hour urine samples for the quantitative determination of calcium and galactosyl hydroxylysine, a bone collagen metabolite. These patients provided demographic information, relevant medical, dental, and dietary history, a profile of their current medications, and the status of their smoking and exercise habits. Urinary excretion of galactosyl hydroxylysine, which is increased in the presence of progressive increased bone resorption, remained within normal values in the patients of this study. These results suggest that the thinning of the jaw bones and subsequent tooth loss of these subjects were osteoporotic processes too limited and too localized to produce measurable increases in urinary bone metabolites.

Adult↗
PubMed1992

Comparison of dietary self-reports with energy expenditure measured using a whole-room indirect calorimeter.

In this study we used a whole-room indirect calorimeter to evaluate the accuracy of self-reported food intake. Daily measured energy expenditure was compared with 2 weeks of self-reported food intake. Additionally, oxidation of each macronutrient was compared with its self-reported intake to assess the accuracy of self-reported dietary composition. Participants (23 through 60 years old) were eight dietitians, eight subjects who were trained in keeping dietary records, and eight subjects who were not trained. Physical activity in the calorimeter was matched to usual daily physical activity. Overall, measured energy expenditure was approximately 200 kcal/day higher than reported metabolizable energy intake. However, this was the result primarily of a few subjects whose self-reported food intake was considerably below measured energy expenditure. Subjects who were trained in record keeping did not differ from untrained subjects. Dietitians had the lowest difference between intake and expenditure; none of them had the large discrepancies between intake and expenditure seen in the other groups. In all groups, there was a much greater discrepancy between self-reported intake and oxidation of each macronutrient than between self-reported total energy intake and expenditure.

Adult↗
PubMed1991

Upper gastrointestinal bleeding following open heart surgery. Predominant finding of aggressive duodenal ulcer disease.

We reviewed our experience with endoscopically evaluated severe upper gastrointestinal hemorrhage following open heart surgery. Of 4892 patients undergoing open heart surgery, 18 (0.4%) sustained upper gastrointestinal hemorrhage requiring endoscopic evaluation. Endoscopy identified the source of bleeding in all cases. No significant complications of endoscopy were observed. Duodenal ulcers (DUs) were found in 16 (89%) of cases and were felt to be the source of bleeding in 15 (83%). Aggressive features, such as multiplicity, large size, or distal location were associated with 13 (81%) of the DU cases. Complications necessitated endoscopic or surgical therapy in eight (44%) patients with DUs. We conclude that aggressive DU disease accounts for the majority of severe upper gastrointestinal bleeding following open heart surgery.

Aged↗
PubMed1991

Decreased duration of emergency department treatment of chronic obstructive pulmonary disease exacerbations with the addition of ipratropium bromide to beta-agonist therapy.

STUDY OBJECTIVES: To determine the benefit of the addition of ipratropium bromide to beta-agonist therapy of acute exacerbations of chronic obstructive pulmonary disease. DESIGN: The trial was randomized and double blinded. SETTING: The study was conducted in the emergency department of Parkland Memorial Hospital, a busy, inner-city, county hospital. INTERVENTIONS: Patients were treated in the medicine emergency department with either the standard regimen of nebulized isoetharine, 0.5 mL of a 1% solution (5.0 mg) diluted to 2.0 mL with normal saline every hour (control group) or with the same regimen plus ipratropium bromide, 54 micrograms (three puffs) after the first isoetharine treatment and 36 micrograms (two puffs) after the second and fourth (experimental group). A placebo metered-dose inhaler used in the same manner as the ipratropium blinded the study to both the patients and medical personnel. MEASUREMENTS AND MAIN RESULTS: The group treated with the addition of ipratropium (30) was discharged from the ED an average of 91 minutes (P less than .05) sooner than the control group (25) and required on the average one less isoetharine treatment (P less than .05). The pulmonary functions tested, forced expiratory volume in the first second, and the forced vital capacity were the same in the two groups initially and on discharge, as identical discharge criteria were used in each group. CONCLUSION: The addition of ipratropium to standard beta-agonist treatment of chronic obstructive pulmonary disease exacerbations shortens the duration of treatment required in the ED.

Acute Disease↗
PubMed1991

Shock wave lithotripsy-induced renal injury.

Both clinical and experimental reports clearly show that shock wave lithotripsy (SWL) causes acute renal effects in a majority, if not all, treated kidneys. SWL-induced acute renal damage may result in severe injury to the nephron, microvasculature, and the surrounding interstitium. In addition, at least three chronic adverse effects have been identified when shock waves are administered at a therapeutic dose. These include (1) an accelerated rise in arterial blood pressure, (2) a decrease in renal function, and (3) an increased rate of stone recurrence. The clinical and experimental data that document tissue injury as a result of shock wave treatment are compelling, but have not allowed us to determine the factors responsible for the adverse acute side effects or to identify conditions that may predispose a patient to serious long-term health problems. Thus, there is an urgent need for incisive, fundamental experimental studies to establish the safe limits for shock wave delivery. To accomplish this goal, animal experimentation is required so that the time course and severity of acute and chronic alterations can be followed in a model that closely mimics human renal structure and functions. The minipig provides this model.

Acute Disease↗
PubMed1991

Heart healthy education. Effectiveness of teaching methods in the workplace.

One fourth to one third of employed workers in this country have at least one of three major risk factors for coronary heart disease. This pilot study examined differences between educational methods used in an occupational setting. The specific aims of the quasi-experimental study were: to determine differences between two groups of subjects who received either group support and instruction or only written instruction; and to determine the association between the practice of heart healthy behaviors and decreased blood cholesterol levels. No significant differences were found between the two groups in cholesterol and behavior changes. However, there was a significant difference between pre- and post-instruction for all subjects. The study documented significant changes in cholesterol levels, cholesterol and fat intake, and weight reduction.

Adult↗
PubMed1990

Etoposide kinetics in patients with obstructive jaundice.

The kinetics and urinary excretion of etoposide and etoposide glucuronide were determined in 11 patients with obstructive jaundice (bilirubin greater than 2.0 mg/dL) and in 23 patients with normal renal and hepatic function. Mean (+/- SE) measurements of clearance (24.5 +/- 2.06 v 26.5 +/- 2.05 mL/min/m2), half-life (5.7 +/- 0.5 v 6.4 +/- 0.5 hours), and volume of distribution (12.4 +/- 1.1 v 13.7 +/- 1.6 L/m2) were not significantly different in patients with jaundice when compared with controls. Similarly, etoposide kinetics in three patients determined during a period of hyperbilirubinemia were not different from measurements made in the same patients following resolution of their obstructive jaundice. In patients with jaundice, 46% of an administered etoposide dose was excreted in the urine as etoposide compared with 35% in controls (P = .15). Urinary excretion of etoposide glucuronide accounted for 29% of an administered etoposide dose in control patients and 15% in those with hepatic obstruction (P = .03). Biliary etoposide excretion measured in four patients with T-tubes was insignificant (less than 2.0% of an administered dose). The calculated renal clearance of etoposide was 11.5 mL/min/m2 in patients with jaundice and 10.4 mL/min/m2 in controls (P = .53). Respective metabolic clearance was 4.9 and 6.9 mL/min/m2 in these two study groups (P = .13). Although hepatic metabolism of etoposide may be slightly decreased in patients with obstructive jaundice, a modest increase in renal etoposide excretion appears to compensate for this change, so that total clearance is similar in the patients with jaundice when compared with controls. No etoposide dose reductions appear to be needed in treating patients with obstructive jaundice who have normal renal function.

Biliary Tract↗
PubMed1989

12S,19- and 12S,20-dihydroxyeicosanoids: novel 12S-hydroxy-5,8-cis-10-trans-14-cis-eicosatetraenoic acid metabolites formed by hydroxylation and reduction in murine lymphocytes.

Murine spleen cells and purified B lymphocytes oxidized arachidonic acid via the lipoxygenase pathway. The major metabolite of both the whole spleen and enriched B lymphocytes was 12S-hydroxy-5,8-cis-10-trans-14-cis-eicosatetraenoic acid. A novel metabolite was observed that did not have an absorbance from 210 to 400 nm, indicating the absence of a conjugated double bond system. The new metabolite was converted to the methyl ester, reduced by platinum oxide, derivatized to the trimethylsilyl ether, and analyzed by gas chromatography-mass spectrometry. A major and a minor component were observed in the analysis of the new compound. The major component had major diagnostic ions indicating the presence of hydroxyl groups at C-12 and C-19. The minor component had major diagnostic ions indicating the presence of hydroxyl groups at C-12 and C-20. The new metabolites are characterized as a mixture of 12S,19- and 12S,20-dihydroxyeicosanoids presumably formed by hydroxylation and reduction of one or more double bonds of 12S-hydroxy-5,8-cis-10-trans-14-cis-eicosatetraenoic acid. These metabolites were formed predominantly with whole spleen lymphocytes but could be detected at longer incubation times or by using 12S-hydroxy-5,8-cis-10-trans-14-cis-eicosatetraenoic acid as the starting substrate with highly enriched B lymphocytes.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1989

Cell-free human amniotic fluid as culture medium for mouse and human embryos.

Differences between murine and human preimplantation embryonic growth in cell-free human amniotic fluid and medium F-10 supplemented with human fetal cord serum were assessed. Two-cell mouse embryos cultured in human amniotic fluid developed more consistently to the expanded blastocyst stage than those cultured in F-10. No significant difference in human preimplantation embryo cleavage was observed between the two culture conditions. However, amniotic fluid was significantly worse than F-10 + human serum in its ability to maintain embryos that could establish pregnancy after transfer.

Amniotic Fluid↗
PubMed1989

Cocaine-associated rhabdomyolysis.

Three male patients developed a total of four episodes of acute rhabdomyolysis associated with documented cocaine intoxication (two caused "crack" and two caused by intravenous cocaine). Included is one patient who developed rhabdomyolysis after injecting cocaine and then redeveloped it 6 months later on "rechallenge." One of the four cases resulted in death related to severe hyperkalemia and ischemic bowel. The remaining three episodes followed a course of nonoliguric renal failure.

Acute Disease↗