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Biomedical subjects

M Arnold

Publications and source records attributed to M Arnold.

At least 73 records · Page 4Linked to original sources
PubMed2000

Correlative Whole-Body FDG-PET and Intraoperative Gamma Detection of FDG Distribution in Colorectal Cancer.

Purpose: 18F-Fluorodeoxyglucose-positron emission tomography (FDG-PET) is the superior imaging modality for detection of primary and recurrent colorectal cancer compared to magnetic resonance imaging (MRI) or computerized tomography (CT). We investigated the feasibility of developing intraoperative procedures for detection of FDG in tumor deposits in order to assist the surgeon in achieving an optimal reduction of tumor burden.Procedures: Fourteen patients (45-83 years of age) were scanned using FDG-PET followed by Gamma Detection Probe evaluation at laparotomy. One patient did not have a pre-operative FDG-PET scan. The collimated detector probe contained a CdZnTe crystal (7mm diameter x 2mm thick). We used a lower window setting of 200 KeV and an open upper window setting. Fasted patients were given an IV bolus of FDG (4.0-5.7 mCi) 15-20 minutes prior to preparation for surgery. Catheterization and the diuretic Lasix were used to remove FDG activity from the bladder. The time from FDG injection to intraoperative GDP data acquisition varied from 58-110 minutes.Results: In all patients, the GDP detected background activity in normal tissues (aorta, colon, liver, kidney, abdominal wall, mesentery, and urinary bladder). The GDP correctly identified single or multiple tumor foci in 13/14 patients as noted by an audible signal from the control unit (3 S.D. above counts obtained from normal tissues). These tumor foci corresponded to regions of high FDG uptake as seen on FDG-PET scans. The one case that the GDP did not localize was a recurrent mucin pseudomyxoma-producing tumor (acellular, mucinous deposits). Ex vivo GDP evaluations demonstrated significant tumor:normal adjacent tissue activity (audible signals in 6/6 tumor samples tested).Conclusions: These data demonstrate that tumors identified from pre-operative whole-body PET scans can be localized during surgery utilizing a gamma probe detector and FDG.

Journal Article↗
PubMed2000

The effects of intestinal infusion of long-chain fatty acids on food intake in humans.

BACKGROUND & AIMS: Dietary fat intake is related to the degree of obesity, but the specific mechanisms by which fats regulate food intake in humans are unclear. We compared food intake suppression, plasma triglyceride appearance, and cholecystokinin (CCK) response after intestinal infusion of oils enriched with C18 fatty acids of increasing unsaturation. METHODS: Food intake and appetite changes after upper intestinal infusion of 0.9% saline, 20% Intralipid, and 20% emulsions of oils enriched with stearic, oleic, and linoleic acids were tested in 10 healthy male volunteers. Plasma triglyceride appearance and CCK release were tested separately in 7 additional volunteers. RESULTS: Intralipid and linoleic acid infusions significantly reduced food intake compared with saline infusion (P<0.05). No changes were observed in appetite ratings. There were no differences in plasma triglyceride response over the initial 75 minutes of intestinal infusion. Plasma CCK concentration increased after all lipid infusions (P<0.001), Intralipid infusion produced the highest increase in plasma CCK (P<0.05), and CCK response was similar between the 3 enriched oil emulsions. CONCLUSIONS: These results indicate marked differences in the ability of C18 fatty acids to reduce food intake that appear not to be related to rate of absorption but may partially be explained by CCK release.

Adult↗
PubMed2000

Clinical use of a computer-enhanced surgical robotic system for endoscopic coronary artery bypass grafting on the beating heart.

The aim of the study was to perform endoscopic coronary artery bypass grafting on the beating heart using a surgical robotic system. In the study, the surgical system ZEUS was used in combination with 3D visualization for endoscopic coronary artery bypass grafting in 25 patients. In a total of 10 cases, the coronary artery anastomosis was done on the beating heart using endoscopic stabilizers without cardiopulmonary bypass. In all cases, total OR time ranged from 4.0 to 8.0 hours (median 5.5 h); the times for endoscopic coronary artery anastomoses ranged from 14 to 50 minutes (median 25 minutes) with no difference between arrested-heart or beating-heart procedures. All patients had an uneventful angiographic control result. An endoscopic coronary artery anastomosis is possible on the arrested as well as on the beating heart.

Cardiopulmonary Bypass↗
PubMed2000

Normal regional right ventricular function and its change with age: a Doppler myocardial imaging study.

BACKGROUND: Doppler Myocardial Imaging (DMI) is a new technique currently being studied for the assessment of regional systolic and diastolic left ventricular (LV) function. No normal values or data on age-related changes in regional myocardial right ventricular (RV) velocities are available. METHODS AND RESULTS: Color DMI was used in 32 healthy volunteers (aged 16-76 years) to derive regional velocities from basal, medial, and apical segments of the RV free wall in the apical 4-chamber view, and from distal segments as well as from the tricuspid annulus in the parasternal long-axis view. Both mitral annular and regional LV velocities (4-chamber, long-axis parasternal view) were also recorded and compared with corresponding RV regional velocities. The M-mode displacement of the cardiac base was measured. Corresponding RV and LV DMI data sets were compared. For longitudinal function, RV free wall systolic velocities were consistently higher than velocities recorded in corresponding LV segments (analysis of variance, P <.05). Older subjects (40-76 years; 13 men, 2 women) had lower RV long-axis regional velocities than younger subjects (16-39 years; 15 men, 2 women), but had higher short-axis RV systolic velocities. For diastolic velocities, a negative correlation between age and the ratio of regional early diastolic to late diastolic velocity was shown for all RV free wall segments (eg, basal segment: r = -0.63, P <.0001). CONCLUSIONS: The right ventricle has higher long-axis regional velocities, a greater excursion of its lateral atrioventricular valve ring, and reduced circumferential shortening velocities compared with the left ventricle. Right ventricular longitudinal shortening is dominant over short-axis function in healthy young subjects. Normal age-related changes of diastolic velocities for each segment of the normal RV free wall have been defined.

Adolescent↗
PubMed2000

Prandial lactate infusion inhibits spontaneous feeding in rats.

To investigate the acute effects of lactate on spontaneous feeding, we infused lactate in the hepatic portal vein (0.5, 1.0, and 1.5 mmol lactate/meal) or in the vena cava (1.0 and 1.5 mmol lactate/meal) of ad libitum-fed rats during their first spontaneous nocturnal meal. Infusions (5 min, 0.1 ml/min) were remotely controlled, and a computerized feeding system recorded meal patterns. In separate crossover tests, meal size decreased independent of the infusion route after 1.0 and 1.5 mmol but not after 0.5 mmol lactate. The subsequent intermeal interval (IMI) tended to decrease only after vena cava infusion of 1.0 mmol lactate. The size of the second nocturnal meal increased after the 1.0 mmol lactate infusion. Hepatic portal infusion of 1.5 mmol lactate increased the satiety ratio [subsequent IMI (min)/meal size (g)] by 175%, which was higher than the insignificant 43% increase after vena cava infusion. Hepatic portal infusion of 1.5 mmol lactate also increased systemic plasma lactate but not glucose concentration at 1 min after the end of infusion. The results are consistent with the idea that meal-induced increases in circulating lactate play a role in the control of meal size (satiation). Moreover, the results suggest that lactate also contributes to postprandial satiety and that the liver is involved in this effect. The exact mechanisms of lactate's inhibitory effects on feeding and the site(s) where lactate acts to terminate meals remain to be identified.

Animals↗
PubMed2000

Inhibition of TNF-alpha production contributes to the attenuation of LPS-induced hypophagia by pentoxifylline.

Cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) are assumed to mediate anorexia during bacterial infections. To improve our understanding of the role that these two cytokines serve in mediating infection during anorexia, we investigated the ability of pentoxifylline (PTX), a potent inhibitor of TNF-alpha production, to block the anorectic effects of the bacterial products lipopolysaccharide (LPS) and muramyl dipeptide (MDP) in rats. Intraperitoneally injected PTX (100 mg/kg body wt) completely eliminated the anorectic effect of intraperitoneally injected LPS (100 microg/kg body wt) and attenuated the anorectic effect of a higher dose of intraperitoneally injected LPS (250 microg/kg body wt). Concurrently, PTX pretreatment suppressed low-dose LPS-induced TNF-alpha production by more than 95% and IL-1beta production 39%, as measured by ELISA. Similarly, high-dose LPS-induced TNF-alpha production was reduced by approximately 90%. PTX administration also attenuated the tolerance that is normally observed with a second injection of LPS. In addition, PTX pretreatment attenuated the hypophagic effect of intraperitoneally injected MDP (2 mg/kg body wt) but had no effect on the anorectic response to intraperitoneally injected recombinant human TNF-alpha (150 ug/kg body wt). The results suggest that suppression of TNF-alpha production is sufficient to attenuate LPS- and MDP-induced anorexia. This is consistent with the hypothesis that TNF-alpha plays a major role in the anorexia associated with bacterial infection.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1999

Factors affecting the risk of contralateral Wilms tumor development: a report from the National Wilms Tumor Study Group.

BACKGROUND: Approximately 1% of children with unilateral Wilms tumor develop contralateral disease. The authors assessed the demographic and histologic features associated with metachronous bilateral Wilms tumor (BWT). METHODS: Characteristics of all children registered on the first four National Wilms Tumor Studies (NWTS) were recorded. The primary endpoint for evaluation was the first appearance of Wilms tumor in the remaining kidney. The cumulative risk of contralateral disease as a function of time since initial presentation was calculated as 1 minus the Kaplan-Meier estimate of remaining free of contralateral disease. A matched case control study was conducted to determine whether the presence and type of nephrogenic rests (NRs) were associated with metachronous BWT. RESULTS: Fifty-eight of 4669 registered children developed metachronous BWT; 38 of 2445 females (expected, 30.2) versus 20 of 2224 males (expected, 27.8) (P = 0.04) developed BWT. The cumulative incidence of contralateral disease 6 years after initial diagnosis decreased from greater than 3% in the first NWTS to approximately 1.5% in the three subsequent studies (P = 0.08). Patients with NRs had a significantly increased risk of metachronous BWT. This was particularly true for young children (20 of 206 age < 12 months compared with 0 of 304 age > 12 months). Data from the matched case control study confirmed the increased relative risk associated with young age and the presence of NRs. CONCLUSIONS: Children younger than 12 months diagnosed with Wilms tumor who also have NRs, in particular perilobar NRs, have a markedly increased risk of developing contralateral disease and require frequent and regular surveillance for several years. Surveillance is also recommended for those with NRs who are diagnosed after the age of 12 months.

Age Factors↗
PubMed1999

Coherence of gamma-band EEG activity as a basis for associative learning.

Different regions of the brain must communicate with each other to provide the basis for the integration of sensory information, sensory-motor coordination and many other functions that are critical for learning, memory, information processing, perception and the behaviour of organisms. Hebb suggested that this is accomplished by the formation of assemblies of cells whose synaptic linkages are strengthened whenever the cells are activated or 'ignited' synchronously. Hebb's seminal concept has intrigued investigators since its formulation, but the technology to demonstrate its existence had been lacking until the past decade. Previous studies have shown that very fast electroencephalographic activity in the gamma band (20-70 Hz) increases during, and may be involved in, the formation of percepts and memory, linguistic processing, and other behavioural and perceptual functions. We show here that increased gamma-band activity is also involved in associative learning. In addition, we find that another measure, gamma-band coherence, increases between regions of the brain that receive the two classes of stimuli involved in an associative-learning procedure in humans. An increase in coherence could fulfil the criteria required for the formation of hebbian cell assemblies, binding together parts of the brain that must communicate with one another in order for associative learning to take place. In this way, coherence may be a signature for this and other types of learning.

Adult↗
PubMed1999

Interrelations between EEG frequency components in sedated intensive care patients during burst-suppression period.

The EEG during basic sedation and burst patterns during electroencephalic burst-suppression patterns (BSP) were analyzed. The aim of EEG analysis was the characterization and quantification of the interrelations between distinct frequency components in both states of sedation. The data for the investigations were derived from the routine EEG derivations of 12 patients with various neurosurgical diseases. It can be demonstrated that the degree of interrelation (amplitude modulation) between a low-frequency component (0-2.5 Hz) and oscillations with higher frequency (3-7.5 and 8-12 Hz) is increased in burst patterns during BSP compared with the EEG during basic sedation. It can be concluded that the degree of interrelations depends on the sedation depth induced by hypnotic drugs.

Adolescent↗
PubMed1999

Assessment of the bioavailability of PAHs in rats exposed to a polluted soil by natural routes: induction of EROD activity and DNA adducts and PAH burden in both liver and lung.

In order to assess bioavailability of polycyclic aromatic hydrocarbons (PAHs) present in soils, male laboratory rats were exposed to litters of control and polluted soils. After 88+/-2 h of exposure, several biomarkers were measured in both liver and lung. When rats were exposed to SIV soil, contaminated by a mixture of at least 13 PAHs, (1) only 2 or 3 PAH compounds were detected in liver and lung; (2) cytochrome P450-dependent monooxygenase activity, followed by 7-ethoxyresorufin O-deethylase (EROD) activity measurement, was highly induced in liver (13-fold-induction) and lung (up to 78-fold); and (3) DNA adducts were significantly increased. For what concerns soil artificially contaminated by only one PAH (phenanthrene or B[a]P), EROD activity was not or fully induced, respectively. These results demonstrate the occurrence of a high bioavailability of PAHs to mammals in natural conditions of exposure. First results concerning DNA adducts must be profound, but they already show that a short exposure of mammals to PAH-polluted soils can lead to potential genotoxic effects. EROD activity can be used as a sensitive biomarker in both liver and lung of rats maintained on litters of soils in the laboratory, and such a test can be used routinely to contribute to risk assessment.

Animals↗
PubMed1999

Chronic arginine aspartate supplementation in runners reduces total plasma amino acid level at rest and during a marathon run.

BACKGROUND: Athletes consume arginine and/or aspartate as potential nutritional ergogenics. Their metabolic effects are controversial and there is some evidence that ingestion of large doses of single amino acids can adversely affect the nitrogen balance or induce an amino acid imbalance. Nevertheless, the general metabolic influence of an arginine aspartate supplementation during a prolonged exercise bout has not yet been investigated. AIM OF THE STUDY: The aim of this study was, therefore, to investigate the general metabolic impact of a chronic supplementation with arginine aspartate in endurance-trained athletes at rest and during a marathon run. METHODS: Fourteen endurance-trained runners participated in this field study which was carried out according to a double-blind crossover design. 15 g of arginine aspartate or a carbohydrate-based placebo were supplemented daily for 14 days before a marathon run. Blood samples for analysis of metabolites and hormones were collected shortly before the run, after 31 km, at the end of the run, and after a recovery period of two hours. Additionally, the respiratory exchange ratio was determined during the run. RESULTS: The plasma level of carbohydrate (glucose, lactate, pyruvate) and fat metabolites (fatty acids, glycerol, beta-hydroxybutyrate), cortisol, insulin, ammonia, lactate dehydrogenase, and creatine kinase as well as the respiratory exchange ratio were unaffected by the supplementation. In contrast, the plasma level of somatotropic hormone, glucagon, urea, and arginine were significantly increased, and the level of most of the remaining plasma amino acids as well as their sum was significantly reduced. CONCLUSIONS: There was no obvious metabolic benefit derived from the chronic supplementation with arginine aspartate. And since furthermore the consequences of a reduction of the total plasma amino acid level are not known, the practice of using single amino acid supplements as potential ergogenics should be critically reevaluated.

3-Hydroxybutyric Acid↗
PubMed1999

Renal cell carcinoma with massive osseous metaplasia and bone marrow elements.

Focal calcifications are frequently seen in renal masses and may be present in renal cell carcinomas. Metaplastic bone formation, on the other hand, is a rare event. We report a unique case of a large calcified renal cell carcinoma with massive osseous metaplasia and bone marrow elements. The clinical and pathologic differential diagnosis for this tumor is discussed along with a review of the literature on this unusual phenomenon.

Biomarkers, Tumor↗
PubMed1999

Heterosexual couples confronting the challenges of HIV infection.

Couples confronted with HIV infection face significant challenges. Little is known about the impact of HIV on heterosexual couples who account for the vast majority of cases worldwide and an increasing proportion of cases in the USA, especially among women. In this study, analysis of data collected on HIV-discordant couples participating in a ten-week support group revealed four major groups of issues: (1) dealing with the emotional and sexual impact on the relationship; (2) confronting reproductive decisions; (3) planning for the future of children and the surviving partner; and (4) disclosure of the HIV infection to friends and family. These findings have implications for the design of interventions to enhance adaptation to HIV for discordant couples.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Unilateral angiolymphoid hyperplasia with eosinophilia involving the left arm and hand.

A case report of recurrent angiolymphoid hyperplasia with eosinophilia (ALHE) in an otherwise healthy 20-year-old female with manifestation of the disease limited to the left arm and hand is presented together with brief evaluation of the literature as well as the features distinguishing ALHE and Kimura's disease. Immunohistochemical investigations support the hypothesis that ALHE represents a reactive inflammatory lesion rather than a benign vascular neoplasm. A viral cause of ALHE (e.g., HHV8 or Epstein-Barr virus (EBV)) could not be demonstrated. The recurrent nature of the disease is shown by this case, which also demonstrates the need for frequent medical and surgical management.

Adult↗
PubMed1999

Metabolic effects of a protein-supplemented carbohydrate drink in marathon runners.

A field study was performed to investigate the acute influence of a milk protein hydrolysate supplemented drink (CHO+PRO) on metabolism during and after a marathon run compared to the same drink without protein (CHO). Carbohydrate metabolites and hormones were not influenced by CHO+PRO. Levels of plasma free fatty acids were significantly lower and levels of urea and most amino acids were significantly higher with CHO+PRO. Sweat urea and ammonia nitrogen excretion during the run as well as urinary 3-methylhistidine excretion during the entire exercise day was similar in both treatments. Urinary total nitrogen was significantly increased and urinary pH decreased with CHO+PRO. It was concluded that the supplemented protein was absorbed and probably at least partially oxidized during the run and that no obvious negative metabolic effects occurred. CHO+PRO did not acutely affect myofibrillar protein breakdown as assessed by the 3-methylhistidine method; however, total body protein breakdown was not measured.

Adult↗
PubMed1999

[The "cost reimbursement" trial regulation in mandatory health insurance: results of a survey of participants].

Since 1994 seven substitution funds of the German statutory health insurance have offered their mandatorily insured members to choose cost reimbursement in place of benefits in kind for a limited testing period. Participants of the cost reimbursement arrangement are considered private patients and are billed accordingly. However, these bills are only in part reimbursed. This study investigates the expectations participants had with respect to the cost reimbursement arrangement as well as the experiences they made. For this purpose a survey among the participants was carried out using a self-administered questionnaire. Most of the 1390 respondents were satisfied with the cost reimbursement arrangement. Organisational, personal and medical advantages which the majority of participants expected were mostly fulfilled. Especially elderly members chose the cost reimbursement arrangement and often made the experience that their doctors spent more time talking to them. The necessary co-payments had hardly any impact on the positive judgment; most participants had an extra private insurance to close the gap of coverage. The results also show that transparency, control of costs and cost-consciousness of patients are improved by the cost reimbursement method. With respect to the preferences of the insured, the results of this study plead for keeping up the offer of cost reimbursement as an alternative to benefits in kind. However, the influence of sickness funds on the care process as well as the equity of care may be negatively affected.

Adult↗