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Biomedical subjects

D R Wagner

Publications and source records attributed to D R Wagner.

69 records · Page 4Linked to original sources
PubMed1991

Muscle metabolism and red cell ATP/ADP concentration during bicycle ergometer in patients with AMPD-deficiency.

6 patients with AMPD-deficiency and 6 control subjects performed exercise on a bicycle ergometer until heart rate was 200 minus age. During exercise the increase of ammonia plasma concentrations was reduced in AMPD-deficient patients compared with that of control subjects. Plasma concentrations of lactate, pyruvate, inosine, hypoxanthine and xanthine increased during exercise in both groups. The concentrations of lactate, inosine and hypoxanthine were lower in AMPD-deficient patients during exercise, the difference was not significant. In AMPD-deficient patients the ATP-concentrations of red blood cells increased during exercise in contrast to control subjects, whereas the ADP amount did not change significantly. Our data suggest that in AMPD-deficient-patients AMP is mainly reduced to adenosine during exercise resulting in decreased ammonia concentrations. The increased concentrations of ATP in red blood cells may be the consequence of increased phosphorylation.

AMP Deaminase↗
PubMed1991

Effects of oral ribose on muscle metabolism during bicycle ergometer in AMPD-deficient patients.

Three patients with AMP deaminase deficiency (AMPD deficiency) performed exercise on a bicycle ergometer with increasing work load without and with administration of ribose (3 g p.o. every 10 min, beginning 1 h before exercise until the end). The patients performed exercise until heart rate was 200 minus age. Maximum capacity was not increased by administration of ribose, but postexertional muscle stiffness and cramps disappeared almost completely in 2 of 3 AMPD-deficient patients. Plasma concentrations of lactate and inosine were increased in AMPD-deficient patients after oral administration of ribose. Our data suggest that ribose may both serve as an energy source and enhance the de novo synthesis of purine nucleotides.

AMP Deaminase↗
PubMed1991

High nocturnal body temperature in premenstrual syndrome and late luteal phase dysphoric disorder.

OBJECTIVE: Because women with late luteal phase dysphoric disorder (LLPDD) experience symptomatic affective states predictably, they can be studied to determine whether there are biological findings related solely to the clinically symptomatic state. The authors sought to answer the question, Does body temperature change with affective state? METHOD: The core body temperature and motor activity patterns of 10 women with premenstrual syndrome (PMS), six of whom also met criteria for LLPDD, and no other psychological or medical illness were compared to those of six women with chronic, noncyclic dysphoria and six asymptomatic comparison women at four phases of the menstrual cycle. RESULTS: The nocturnal temperatures of the women with PMS/LLPDD were significantly higher than those of the comparison subjects across the entire menstrual cycle, but there were no differences in nocturnal activity levels. The women with noncyclic dysphoria had a mean nocturnal temperature in the follicular phase as high as that of the women with PMS/LLPDD. The temperatures of all women were higher in the luteal phase than in the follicular phase. CONCLUSIONS: These findings suggest that in the future investigators should document menstrual cycle phase in all female subjects and, when studying body temperature, should carefully monitor symptomatic state in comparison subjects.

Adult↗
PubMed1981

Motilin-antimotilin reaction reveals two antigenic determinants in motilin.

The reaction of motilin with four rabbit antimotilin sera raised by immunization with synthetic porcine motilin-bovine serum albumin conjugate was studied with respect to various binding parameters and specificity. All four antisera exhibited an extremely high degree of specificity and high affinity (K greater than 10(11) M-1) for porcine motilin. Studying the various synthetic motilin fragments. These antisera appeared to contain binding sites reacting strongly with the N-terminal sequence in which the first three amino acid residues are essential for high affinity binding. One of the antisera, R-3-6, appeared to contain approximately 20% of its binding sites with high affinity for C-terminus-containing fragments. These results suggest that motilin possesses two antigenic domains along its primary structure; one contains the N-terminal tripeptide and the other contains the C-terminal nanopeptide as essential parts. Thus, in addition to heterogeneity in affinity, a given antibody preparation may be heterogenous with respect to the specificity along the sequence of a peptide. Gel filtration studies of the methanol extracts of human and dog plasma indicated that an immunoreactive motilin-like material with a molecular size similar to natural porcine motilin was measured by our routine radioimmunoassay.

Animals↗
PubMedDate not supplied

Adenosine inhibits lipopolysaccharide-induced cardiac expression of tumor necrosis factor-alpha.

Tumor necrosis factor-alpha (TNF-alpha) is elevated in the failing heart. Very little is known about regulation of TNF-alpha in cardiomyocytes. TNF-alpha expression by macrophages is diminished by adenosine. Therefore, we hypothesized that a similar mechanism might occur in the heart. Neonatal rat myocytes were stimulated with lipopolysaccharide (LPS), and TNF-alpha was measured by ELISA. In the absence of LPS, myocytes did not release TNF-alpha in the medium. After exposure to LPS, TNF-alpha increased to 70.1+/-3.5 pg/mL at 6 hours. Immunofluorescent staining confirmed that TNF-alpha was expressed in myocytes. Adenosine decreased TNF-alpha in a dose-dependent manner (1 to 100 micromol/L, 37% to 65% decrease, P<.01). Adenosine also decreased TNF-alpha in cell homogenates by 78% (P<.0001). The effect of adenosine could be replicated by the A2 agonist PD-125944 (DPMA), by cAMP agonists 8-bromo-cAMP, forskolin, and Ro 20-1724, but not by A1 and A3 agonists. Conversely, the effect of adenosine could be suppressed by the adenylate cyclase inhibitor MDL-12,330. Adenosine also inhibited TNF-alpha in adult rat ventricular myocytes (-60%, P<.005) and rat papillary muscles (-55%, P<.05). In neonatal myocytes, adenosine normalized LPS-induced calcium changes and improved LPS-induced negative inotropic (P<.01) and negative lusitropic (P<.01) effects. Our results demonstrate that adenosine can significantly diminish TNF-alpha levels in the heart. The effect appears to be mediated by the A2 receptor and transduced through a G protein-adenylyl cyclase pathway. These results may explain some cardioprotective effects of adenosine and provide a novel pharmacological intervention in congestive heart failure.

Adenosine↗
PubMedDate not supplied

Evaluation of "closed" vs "open" systems for the delivery of peptide-based enteral diets.

BACKGROUND: The study was designed to quantitate factors such as preparation time, waste, and contamination associated with three different feeding systems for peptide-based diets and to determine appropriate hang times. METHODS: Intensive care unit patients were randomized to receive a peptide-based diet in 1500-mL prefilled, sterile closed-system containers (CS) infused more than 24 hours, as open systems decanted from cans (OS-Can), or as open systems mixed from powder (OS-Powder). Open-system groups were provided a 12-hour supply twice daily in commercially clean 1-L bags with preattached sets. Samples were taken for culture during preparation and after infusion. Preparation time, initial and final microbial concentrations, and total waste were quantified. RESULTS: Preparation time was significantly shorter for CS than for OS-Can or for OS-Powder (2 minutes vs 7.5 minutes vs 13.0 minutes). Initially, 100% of the OS-Powder and 30% of the OS-Can bags were contaminated, with significant contamination exceeding 10(4) colony-forming units/mL in 40% and in 5% of the bags, respectively. On final culture, significant contamination occurred in only 2% of the CS bags compared with 83% of the OS-Powder and 60% of the OS-Can bags. Average time from potential initial contamination to final culture in CS was 49.9 hours vs 38.8 hours for OS-Can and 32 hours for OS-Powder. Total waste was greater in CS than in OS-Can or OS-Powder but could be eliminated by extending allowable hang times. CONCLUSIONS: Nonvented closed-delivery containers may be safely infused for up to 48 hours. They are associated with reduced labor and contamination.

Enteral Nutrition↗
PubMedDate not supplied

Human growth hormone release is decreased during sleep in temporal isolation (free-running).

Growth hormone (hGH) secretion was measured during sleep in 10 healthy male subjects isolated from all time cues. HGH concentrations following sleep onset were compared between scheduled sleep episodes (entrainment) and self-selected sleep episodes (free-running). Peak sleep-related hGH values were decreased significantly during free-running. The duration of the first slow wave sleep (SWS) episode and the latency to the first REM sleep episode also decreased significantly during free-running. The latencies from sleep onset to SWS and to peak hGH secretion did not differ between entrainment and free-running. These results suggest that sleep-related hGH secretion begins 'on time' during free-running, but is terminated earlier. Thus, while sleep onset facilitates hGH release, the timing of other stages of sleep such as REM may alter the magnitude of sleep-related hGH secretion.

Adult↗
PubMedDate not supplied

Effect of propranolol on portal vein hemodynamics in patients with liver cirrhosis: assessment by duplex sonography.

Portal vein hemodynamics of 11 patients with cirrhosis confirmed by liver biopsy and of 5 healthy volunteers were studied by duplex sonography during oral treatment with 80 mg propranolol. One hour after oral administration of 80 mg propranolol, portal blood flow measured by duplex sonography was reduced by 35.3% in cirrhotic patients and by 28.1% in healthy volunteers (n.s.). Portal blood flow reduction was maximal three hours after administration of propranolol (46.9%). During the follow up of cirrhotic patients to whom 80 mg propranolol was administered daily, the reduction of portal blood flow persisted and was 45.0% after 1 week and 37.0% after 4 weeks. Each cirrhotic patient responded with a reduction in portal blood flow. Duplex sonography was found to be an accurate follow-up method of cirrhotic patients under therapy with propranolol.

Administration, Oral↗
PubMedDate not supplied

Bioelectrical impedance as a discriminator of pressure ulcer risk.

In an effort to identify objective measures of tissue structure and function associated with pressure ulcer risk, bioelectrical impedance analysis (BIA) was measured in three progressively larger zones over the trochanter and coccyx in patients assessed at high risk for pressure ulcers (HR group) and age-matched normal controls (CONT group). Local BIA measures were significantly lower in the HR group for each individual site and zone (p < .01). Full-thickness tissue biopsies obtained from each measurement zone did not differ between groups. However, additional nutritional and metabolic parameters were significantly different (p < or = .05). These results suggest that local BIA may be useful in assessing pressure ulcer risk.

Aged↗