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Biomedical subjects

E Knapp

Publications and source records attributed to E Knapp.

At least 19 recordsLinked to original sources
PubMed2003

Dynamics of viral and proviral loads of feline immunodeficiency virus within the feline central nervous system during the acute phase following intravenous infection.

Animal models of human immunodeficiency virus 1, such as feline immunodeficiency virus (FIV), provide the opportunities to dissect the mechanisms of early interactions of the virus with the central nervous system (CNS). The aims of the present study were to evaluate viral loads within CNS, cerebrospinal fluid (CSF), ocular fluid, and the plasma of cats in the first 23 weeks after intravenous inoculation with FIV(GL8). Proviral loads were also determined within peripheral blood mononuclear cells (PBMCs) and brain tissue. In this acute phase of infection, virus entered the brain in the majority of animals. Virus distribution was initially in a random fashion, with more diffuse brain involvement as infection progressed. Virus in the CSF was predictive of brain parenchymal infection. While the peak of virus production in blood coincided with proliferation within brain, more sustained production appeared to continue in brain tissue. In contrast, proviral loads in the brain decreased to undetectable levels in the presence of a strengthening PBMC load. A final observation in this study was that there was no direct correlation between viral loads in regions of brain or ocular tissue and the presence of histopathology.

Animals↗
PubMed2001

Hypersensitivity reactions associated with recombinant tissue-type plasminogen activator and urokinase.

Anaphylaxis or angioedema in response to recombinant tissue-type plasminogen activator or urokinase have been reported in only a few isolated cases. Both agents are endogenous proteins and thus considered non-antigenic. Activation of fibrinolysis may per se facilitate anaphylactoid reactions by pathophysiologic pathways that are not well understood. We report a unique case, review the literature and discuss implication for the clinician. The 25-year-old patient underwent thrombolytic treatment for extensive thrombosis of pelvic and deep lower extremity veins. The patient developed protracted anaphylactoid reactions during recombinant tissue-type plasminogen activator continuous intravenous infusion. After changing treatment to urokinase, the same symptoms recurred with more severe intensity, despite corticosteroid premedication. Symptoms resolved within hours after treatment with histamine receptor blockers. This unique observation, i.e. sequential occurrence of anaphylactoid reactions during recombinant tissue plasminogen activator and urokinase treatments, adds to existing evidence for an unspecific non-antigenic pathomechanism, and for a class effect of thrombolytics. Steroids do not prevent, but histamine receptor blockers seem to be an effective treatment of this unusual complication of thrombolytic therapy.

Abdominal Pain↗
PubMed2001

Conundrum of the lack of defective RNAs (dRNAs) associated with tobamovirus Infections: dRNAs that can move are not replicated by the wild-type virus; dRNAs that are replicated by the wild-type virus do not move.

Two classes of artificially constructed defective RNAs (dRNAs) of Tobacco mosaic virus (TMV) were examined in planta with helper viruses that expressed one (183 kDa) or both (126 and 183 kDa) of the replicase-associated proteins. The first class of artificially constructed dRNAs had the helicase and polymerase (POL) domains deleted; the second had an intact 126-kDa protein open reading frame (ORF). Despite extremely high levels of replication in protoplasts, the first class of dRNAs did not accumulate in plants. The dRNAs with an intact 126-kDa protein ORF were replicated at moderate levels in protoplasts and in planta when supported by a TMV mutant that expressed the 183-kDa protein but not the 126-kDa protein (183F). These dRNAs were not supported by helper viruses expressing both replicase-associated proteins. De novo dRNAs were generated in plants infected by 183F but not in plants infected with virus with the wild-type replicase. These novel dRNAs each contained a new stop codon near the location of the wild-type stop codon for the 126-kDa protein and had most of the POL domain deleted. The fact that only dRNAs that contained a complete 126-kDa protein ORF moved systemically suggests that expression of a functional 126-kDa protein or the presence of certain sequences and/or structures within this ORF is required for movement of dRNAs. At least two factors may contribute to the lack of naturally occurring dRNAs in association with wild-type TMV infections: an inability of TMV to support dRNAs that can move in plants and the inability of dRNAs that can be replicated by TMV to move in plants.

Defective Viruses↗
PubMed1999

Evidence for restricted muscle blood flow during speed skating.

INTRODUCTION: We have previously hypothesized restricted muscle blood flow during speed skating, secondary to the high intramuscular forces intrinsic to the unique posture assumed by speed skaters and to the prolonged duty cycle of the skating stroke. METHODS: To test this hypothesis, we studied speed skaters (N = 10) during submaximal and maximal cycling and in-line skating, in both low (knee angle = 107 degrees) and high (knee angle = 112 degrees) skating positions (CE vs SkL vs SkH). Supportive experiments evaluated muscle desaturation and lactate accumulation during on-ice speed skating and muscle desaturation during static exercise at different joint positions. RESULTS: Consistent with the hypothesis were reductions during skating in VO2peak (4.28 vs 3.83 vs 4.26 L x min(-1)), the VO2 at 4 mmol x L(-1) blood lactate (3.38 vs 1.93 vs 3.31 L x min(-1)), and cardiac output during maximal exercise (33.2 vs 25.3 vs 25.6 L x min(-1)). The reduction in maximal cardiac output was not attributable to differences in HRmax (197 vs 192 vs 193 b x min(-1)) but to a reduction in SVmax (172 vs 135 vs 134 mL x beat(-1)). The reduction in SV appeared to be related to an increased calculated systemic vascular resistance (354 vs 483 vs 453 dynes x s(-1) x cm(-1)). During maximal skating there was also a greater % O2 desaturation of the vastus lateralis based on near infrared spectrophotometry (50.3 vs 74.9 vs 60.4% of maximal desaturation during cuff ischemia). The results were supported by greater desaturation with smaller knee angles during static exercise and by greater desaturation and accelerated blood lactate accumulation during on-ice speed skating in the low vs high position. The results of this study support the hypothesis that physiological responses during speed skating are dominated by restriction of blood flow, attributable either to high intramuscular forces, the long duty cycle of the skating stroke, or both.

Adult↗
PubMed1998

Slow infusion feedings enhance duodenal motor responses and gastric emptying in preterm infants.

It is unknown whether it is better to feed preterm infants intragastrically by bolus or continuous infusion. This study compared the effect of 2 feeding rates on antral and duodenal motor responses and gastric emptying. Continuous perfusion manometry with a low-compliance machine was performed in 22 infants given feedings at 2 infusion rates. Gastric emptying was also assessed by using a dye-dilution technique to determine whether changes in motor response were reflected by changes in function. The number of antral contractions with both feeding rates decreased from that seen during fasting. Duodenal motor responses increased when infants were fed by slow infusion and decreased when they were fed by rapid infusion. Infants emptied 12 mL/kg of a 20-mL/kg feeding by 20 min after completion of the feeding given by slow infusion concomitantly with the increase in duodenal motor activity but only 8 mL/kg by 20 min after completion of the bolus feeding, when duodenal motor activity decreased (P < 0.01). Two hours after completion of the feeding, volumes remaining in the stomach after slow infusion were one-ninth those remaining after bolus feeding. When preterm infants are fed by slow infusion over 120 min, their duodenal motor responses are more like those observed in adults and their gastric contents are emptied faster and more completely than when they are fed with a rapid bolus.

Duodenum↗
PubMed1997

Shoulder rotator torque and wheelchair dependence differences of National Wheelchair Basketball Association players.

OBJECTIVE: Shoulder rotator muscle imbalances can contribute to subacromial impingement. The forces and movement patterns of wheelchair locomotion may contribute to these imbalances. This study attempted to determine whether National Wheelchair Basketball Association players of differing classifications had significant differences (p < or = .05) in concentric isokinetic peak shoulder rotator torque and torque ratios, and wheelchair locomotion dependence. DESIGN: Fifty-seven (class 1 = 12, class 2 = 24, class 3 = 21) of 117 total tournament participants (class 1 = 25, class 2 = 49, class 3 = 43) served as the convenience sample of volunteers for the survey portion, and 33 of these subjects (class 1 = 11, class 2 = 12, class 3 = 10) also entered the isokinetic portion of this study. SETTING: National wheelchair basketball tournament. RESULTS: Class 1 and 2 players had greater wheelchair dependence than class 3 players (p < or = .05). Peak torque or torque ratios generally did not differ among player classifications or with other populations. Class 1 players had weaker nondominant shoulder external rotator torque production at 60 degrees/sec (p < or = .03) compared with other classes and at 180 degrees/sec compared with class 3 players (p = .02), suggesting an inability to develop the "attenuation of dominance" noted among other groups. Diminished torque-producing capacity at 60 degrees/sec related to greater wheelchair dependence among class 1 players (p = .034). CONCLUSIONS: Class 1 players failed to demonstrate the acquired shoulder external rotator torque symmetry evident among class 2 and 3 players (with specific weakness of the nondominant shoulder external rotators). This torque symmetry difference was related to their greater dependence on wheelchair locomotion.

Adult↗
PubMed1995

Localization of fruit tree viruses by immuno-tissue printing in infected shoots of Malus sp. and Prunus sp.

Immuno-tissue printing protocols for the localization of apple chlorotic leaf spot virus (ACLSV), stem grooving virus (SGV) and plum pox virus (PPV) in shoots of Prunus and Malus in vitro have been established for routine diagnosis in a virus elimination program. Since these viruses belong to different virus genera, the protocols were adapted according to the properties of the virus under investigation. Accumulation of ACLSV was highest in the base of the stem and decreased towards the apex of the shoots. ACLSV was found in the epidermis, the cortex, in the vascular bundles, but seldom in the pith tissue of in vitro apple shoots. ACLSV immuno-tissue printing was as sensitive as ELISA and the intensity of color signals in immuno-tissue prints correlated with absorbance values by two-step ELISA. SGV could be detected by immuno-tissue prints at infectivity levels, where it reacted negative in ELISA. SGV accumulated in the vascular bundles, occurred locally in the parenchymatic tissue, was found in high amounts in young leaves near the meristem, but not within the meristem. PPV was detected in all tissue types of stem sections with an irregular pattern reflecting the in vivo situation causing problems with detection. Discrimination of poorly and heavily infected shoots was possible with the naked eye.

Culture Techniques↗
PubMed1993

Increased levels of serum neopterin and decreased production of neutrophil superoxide anions in chronic heart failure with elevated levels of tumor necrosis factor-alpha.

OBJECTIVES: The purpose of this study was to examine the role of tumor necrosis factor-alpha and tetrahydrobiopterin and superoxide anion release from neutrophils in severe chronic heart failure. BACKGROUND: Previous studies have demonstrated elevated production of tumor necrosis factor-alpha and free radical-induced endothelial cell damage in severe heart failure. METHODS: Plasma and serum levels of immunoreactive interleukin-1, interleukin-6, interferon-gamma, neopterin and tumor necrosis factor-alpha and the release of superoxide anions from circulating neutrophils both at basal conditions and after triggering with f-Met-Leu-Phe or phorbol 12-myristate 13-acetate were measured in 16 patients with severe heart failure and in 11 healthy control subjects. RESULTS: Circulating levels of tumor necrosis factor-alpha and neopterin were elevated in patients with heart failure compared with values in control subjects. A significant correlation between the two was found. Basal and phorbolester-triggered release of oxygen radicals from neutrophils was not affected in patients with heart failure. However, formylpeptide-stimulated release of oxygen radicals by neutrophils was significantly reduced. CONCLUSIONS: Suppressed neutrophil function in patients with heart failure exhibiting elevated levels of tumor necrosis-alpha factor may indicate self-protection against the deleterious effects of neutrophil-derived oxygen radicals. Through induction of tetrahydrobiopterin synthesis (as reflected by increased neopterin), tumor necrosis factor-alpha may affect nitric oxide synthesis.

Atrial Natriuretic Factor↗
PubMed1993

The relative efficacy of high-dose buspirone and alprazolam in the treatment of panic disorder: a double-blind placebo-controlled study.

This 8-week double-blind placebo-controlled trial investigated the relative efficacy and safety of alprazolam and buspirone in the treatment of panic disorder. Alprazolam (mean +/- SD dose 5.2 +/- 2.6 mg) produced a rapid and sustained improvement in panic attacks, anxiety, phobias, and disability and was superior to buspirone (mean +/- SD dose 61 +/- 26.5 mg) and placebo on all of these measures on completer (n = 85) and endpoint analysis (n = 92). Although higher doses of buspirone were used in this study than in previous trials, buspirone was not superior to placebo on any of the outcome measures. The results were disappointing in light of buspirone's benign side effect profile and low abuse potential.

Adolescent↗
PubMed1992

Proinflammatory cytokines in cardiac myxomas.

Serum levels of various cytokines were measured in three patients with cardiac myxomas presenting with and without constitutional symptoms, immunological features and elevated plasma levels of interleukin-6. Interleukin-6 but not other cytokines (interleukin-1, tumour necrosis factor-alpha, interferon-gamma) relate to immunological features of the patients. Circulating levels of atrial natriuretic peptide correspond to haemodynamic changes but not to the tumour-bearing state itself.

Atrial Natriuretic Factor↗
PubMed1992

Relation of triglyceride metabolism and coronary artery disease. Studies in the postprandial state.

The status of fasting triglycerides as a risk factor for coronary artery disease (CAD) has been considered weak because in multivariate analyses, triglycerides tend to be eliminated by high density lipoprotein (HDL) cholesterol. To further evaluate the role of triglycerides in CAD, we employed postprandial lipemia as a more informative means of characterizing triglyceride metabolism. In 61 male subjects with severe CAD and 40 control subjects without CAD as verified by angiography, we measured cholesterol; triglycerides; HDL cholesterol; HDL2 cholesterol; and apolipoproteins A-I, A-II, and B in fasting plasma and triglycerides before and 2, 4, 6, and 8 hours after a standardized test meal. Both the maximal triglyceride increase and the magnitude of postprandial lipemia (area under the triglyceride curve over 8 hours after the meal) were higher in cases than in control subjects. Single postprandial triglyceride levels 6 and 8 hours after the meal were highly discriminatory (p < 0.001), and by logistic-regression analysis displayed an accuracy of 68% in predicting the presence or absence of CAD. In this respect, accuracy was higher than that of HDL2 cholesterol (64%) and equal to that of apolipoprotein B (68%), the most discriminatory fasting parameter. Multivariate logistic-regression analysis was performed to reduce the number of risk factors to those that were statistically independent. This statistical procedure selected postprandial but not fasting triglycerides into the most accurate multivariate model, which also contained the accepted risk factors HDL2 cholesterol, apolipoprotein B, and age. This model classified 82% of subjects correctly. We conclude that triglycerides are independent predictors of CAD in multivariate analyses including HDL cholesterol, provided that a challenge test of triglyceride metabolism such as postprandial lipemia is used. The study suggests that the metabolism of triglycerides is a critical determinant of cholesterol metabolic routing. The findings support the concept that the negative association between HDL cholesterol levels and CAD actually originates in part from a positive relation between CAD and plasma triglycerides, as ascertained in the postprandial state.

Adult↗
PubMed1991

[An idiopathic floating left-ventricular thrombus].

Four weeks after appendicectomy a 28-year-old man developed dragging pains in the left calf. Left popliteal, posterior tibial and dorsalis pedis arteries could not be palpated. Angiography revealed an embolic occlusion of the left superior femoral artery at the level of the adductor canal. Echocardiography demonstrated a pedunculated left ventricular thrombus, 3.5 x 2.0 cm, as a possible source of the embolus. After successful trifurcation embolectomy and saphenous vein patch-plasty acenocoumarol, 4 mg/d and heparin, 3 x 7500 IU/d were administered. Because the thrombus failed to shrink, systemic thrombolysis, initially 750,000 IU streptokinase and 3000 IU heparin i.v., was begun. After five days the thrombus diameter had decreased to 0.7 cm. But because thrombus movement had increased, streptokinase was replaced by 70 IU/d ancrod i.v. The thrombus completely disappeared within two weeks. The patient was symptom-free during the period of anticoagulation with acenocoumarol. Six months later echocardiography confirmed the absence of thrombus in the left ventricle.

Acenocoumarol↗
PubMed1990

Predictive value of computed tomographic determination of the patency rate of aortocoronary venous bypasses in relation to angiographic results.

From 1978 to 1988, 300 patients with 616 aortocoronary venous bypasses underwent computed tomography (CT) 3 months after surgery, and angiography 1 day after CT. Both angiographic patency rate and CT patency rate were 75%. The sensitivity of the CT test for the detection of patent bypass grafts was 90 +/- 1.4%, the specificity of the CT test for the detection of occluded bypass grafts 72 +/- 3.6%. The observed predictive value of a patent CT test resulted in angiographically patent bypasses in 91 +/- 1.3%; the observed predictive value of an occluded CT test resulted in angiographically occluded bypasses in 71 +/- 3.6%. The low specificity for detecting occluded grafts is a considerable limitation of the technique. The pre-post-test patency ratio curve shows better predictive values for the CT test when there is a low pre-test likelihood of patency than when this is high. Patients with a high pre-test likelihood of occlusion, but who actually have patent coronary artery bypasses are most likely to benefit from this non-invasive test.

Angiography↗
PubMed1990

[Mitochondria number as a prognostic parameter in dilated cardiomyopathy. A long-term follow-up study].

According to morphological criteria of the myocardium, patients with clinical and hemodynamic signs of dilated cardiomyopathy were divided into three groups. Group I: patients with 1-2 mitochondria per 2 sarcomeres (n = 46); Group II: patients with more than 2 mitochondria per 2 sarcomeres (n = 47); Group III: patients with histological findings of myocarditis in the past (n = 33). Mean follow-up in groups I, II, III was 29, 22, 26 months, respectively (6-58, 3-52, 3-62/median 29, 18, 22). Clinical parameters were evaluated at the beginning and at the end of the prospective observation and were classified clinically as "improved, unchanged, deteriorated"; "heart transplantation", "death of cardial causes", "death of other than cardial causes" or "lost to follow up" were the other endpoints of the observation. At the beginning there were no hemodynamic differences between groups I, II, III, except significant difference in ejection fraction and mean ventricular shortening velocity between groups I and II. Scored together with the clinical symptoms "deterioration" and "death of cardial causes" as endpoints, survival rates without event up to 5 years in group I were 83 +/- 7% compared with group II 33 +/- 13% and group III 86 +/- 8%. There were significant differences (p less than 0.01). We conclude that the increased number of mitochondria per 2 sarcomeres in biopsy specimen of patients with dilated cardiomyopathy can be a significant parameter of deteriorated prognosis.

Adult↗
PubMed1989

[Changes in the catecholamine plasma level 3 months after aortocoronary bypass operation].

Plasma catecholamine levels were obtained during diagnostic heart catheterization from the pulmonary artery and aorta and, similarly, renin levels were determined in the pulmonary artery in 31 patients with coronary heart disease and 18 normal controls. 3 months after aorto-coronary bypass surgery the patients with coronary heart disease underwent repeat heart catheterization and the epinephrine, norepinephrine and renin levels were compared with those obtained before operation. Norepinephrine decreased in the aorta from (means +/- SEM) 475 +/- 57 pg/ml to 360 +/- 38 pg/ml (p less than 0.001) postoperatively (controls 225 +/- 21 pg/ml). Epinephrine decreased from 121 +/- 11 pg/ml to 108 +/- 16 pg/ml (p less than 0.001) postoperatively (controls 84 +/- 9 pg/ml). This shows that postoperative relief from myocardial ischemia is associated with normalization of the preoperatively elevated plasma catecholamine levels).

Adult↗