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Biomedical subjects

D J Huber

Publications and source records attributed to D J Huber.

At least 19 recordsLinked to original sources
PubMed1995

[Magnetic resonance tomography in disorders of the rotator cuff].

Magnetic resonance imaging (MRI) has become a powerful diagnostic tool for the evaluation of the painful shoulder in general and of the diseased rotator cuff in particular. MRI evaluates cuff disease in terms of tendon morphology and pathologic signal alterations within diseased cuff tendons. Additionally, MRI displays important pathoanatomic changes of the coracoacromial arch which are predisposing factors for the development of shoulder impingement syndrome and cuff disease. The accuracy of MRI in diagnosing small rotator cuff tears and in assessing the integrity of the labral-ligamentous complex is improved by the intraarticular injection of a suitable contrast agent. In the preoperative assessment of patients with cuff disease, MR arthrography enhances the staging of the disease and allows a more confident exclusion of concomitant lesions of the shoulder joint.

Contrast Media↗
PubMed1991

Endoglycanase-Catalyzed Degradation of Hemicelluloses during Development of Carnation (Dianthus caryophyllus L.) Petals.

Large molecular-size hemicelluloses, including xyloglucan, decreased in quantity during development of carnation (Dianthus caryophyllus L. cv White Sim) petals, along with a relative increase in polymers with an average size of 10 kilodaltons. An enzyme extract from senescing petal tissue depolymerized the large molecular-size hemicelluloses in a pattern similar to that occurring in vivo during petal development. The products generated in vitro were composed of polymeric and monomeric components, the latter consisting primarily of xylose, galactose, and glucose. The 10 kilodalton hemicelluloses were resistant to in vitro enzymic hydrolysis. Glycosyl-linkage composition of the large molecular-size polymers provided evidence for the presence of xyloglucan with smaller amounts of arabinoxylan and arabinan. The 10 kilodalton polymers were enriched in mannosyl and 4-linked glucosyl residues, presumably derived from glucomannan. During petal development or enzymic hydrolysis, no change was observed in the relative glycosyl-linkage composition of the large molecular-size hemicelluloses. The in vitro activity of carnation petal enzymes active toward native hemicelluloses increased threefold at the onset of senescence and declined slightly thereafter. Gel chromatography revealed 23 and 12 kilodalton proteins with hemicellulase activity. The enzymes hydrolyzed the large molecular-size hemicelluloses extensively and without formation of monomers. Endoxylanase activity was detected in the partially purified enzyme preparation. Xyloglucan was depolymerized in the absence of cellulase activity, suggesting the presence of a xyloglucan-specific glucanase. These data indicate that the hemicellulose molecular-size changes observed during development of carnation petals are due, in part, to the enzymic depolymerization of large molecular-size hemicelluloses.

Journal Article↗
PubMed1988

Uronic Acid products release from enzymically active cell wall from tomato fruit and its dependency on enzyme quantity and distribution.

Isolated cell wall from tomato (Lycopersicon esculentum Mill. cv Rutgers) fruit released polymeric (degree of polymerization [DP] > 8), oligomeric, and monomeric uronic acids in a reaction mediated by bound polygalacturonase (PG) (EC 3.2.1.15). Wall autolytic capacity increased with ripening, reflecting increased levels of bound PG; however, characteristic oligomeric and monomeric products were recovered from all wall isolates exhibiting net pectin release. The capacity of wall from fruit at early ripening (breaker, turning) to generate oligomeric and monomeric uronic acids was attributed to the nonuniform ripening pattern of the tomato fruit and, consequently, a locally dense distribution of enzyme in wall originating from those fruit portions at more temporally advanced stages of ripening. Artificial autolytically active wall, prepared by permitting solubilized PG to bind to enzymically inactive wall from maturegreen fruit, released products which were similar in size characteristics to those recovered from active wall isolates. Extraction of wall-bound PG using high concentrations of NaCl (1.2 molar) did not attenuate subsequent autolytic activity but greatly suppressed the production of oligomeric and monomeric products. An examination of water-soluble uronic acids recovered from ripe pericarp tissue disclosed the presence of polymeric and monomeric uronic acids but only trace quantities of oligomers. The significance in autolytic reactions of enzyme quantity and distribution and their possible relevance to in vivo pectin degradation will be discussed.

Journal Article↗
PubMed1988

Products Released from Enzymically Active Cell Wall Stimulate Ethylene Production and Ripening in Preclimacteric Tomato (Lycopersicon esculentum Mill.) Fruit.

Enzymically active cell wall from ripe tomato (Lycopersicon esculentum Mill.) fruit pericarp release uronic acids through the action of wall-bound polygalacturonase. The potential involvement of products of wall hydrolysis in the induction of ethylene synthesis during tomato ripening was investigated by vacuum infiltrating preclimacteric (green) fruit with solutions containing pectin fragments enzymically released from cell wall from ripe fruit. Ripening initiation was accelerated in pectin-infiltrated fruit compared to control (buffer-infiltrated) fruit as measured by initiation of climacteric CO(2) and ethylene production and appearance of red color. The response to infiltration was maximum at a concentration of 25 micrograms pectin per fruit; higher concentrations (up to 125 micrograms per fruit) had no additional effect. When products released from isolated cell wall from ripe pericarp were separated on Bio-Gel P-2 and specific size classes infiltrated into preclimacteric fruit, ripening-promotive activity was found only in the larger (degree of polymerization >8) fragments. Products released from pectin derived from preclimacteric pericarp upon treatment with polygalacturonase from ripe pericarp did not stimulate ripening when infiltrated into preclimacteric fruit.

Journal Article↗
PubMed1987

Soft tissue pseudotumor following intramuscular injection of "DPT": a pitfall in magnetic resonance imaging.

We report the time-dependent magnetic resonance imaging (MRI) changes that resulted from an intramuscular injection of a commonly-used pediatric sedation regiment ("DPT"). These changes at the site of injection consist of a focal abnormality characterized by a slight increase in signal intensity on T1 weighted images and markedly increased signal intensity on T2 weighted images. Alterations in signal are detectable almost immediately after the injection and progress over the first 31 hours. This abnormality, which could be mistaken for real disease, persists up to 36 days following injection.

Child↗
PubMed1987

Nuclear magnetic resonance spectroscopy of acute and evolving pulmonary hemorrhage. An in vitro study.

The proton NMR relaxation times of lung tissue were determined in a rabbit model of acute and evolving pulmonary hemorrhage (PH). Pure PH was simulated by injecting blood into a single lobe using endobronchial catheterization. In vitro spectroscopic measurements of T1 and T2 were made and total water content was determined on lung samples that were excised at regular intervals. T1 and T2 were markedly longer in lungs with acute PH than in normal lungs (T1: 818 +/- 44 vs. 643 +/- 4 msec; T2 164.0 +/- 16.3 vs. 88.1 +/- 3.4 msec). Within the first 24 hours, evolving PH was characterized by a rapid and progressive decrease in T1 (-50%) and T2 (-57%). Up to seven days after the instillation of blood, the T1 (450 +/- 43 msec) and T2 (69.7 +/- 1.9 msec) of lung with modeled PH remained below values of normal lung. The observed shortening of the relaxation times of lung disease with PH was closely paralleled by a decrease in tissue water content.

Animals↗
PubMed1986

MR imaging of the normal shoulder.

Magnetic resonance (MR) images of the shoulders of a healthy volunteer were obtained in axial, sagittal, and coronal orientations using a 0.5-T imaging system. Multiple high-resolution spin-echo images were generated using an off-center zoom technique and a specially designed surface coil. Several anatomic structures, including the rotator cuff, long biceps tendon, articular capsule, muscles, and bones, were visualized. The coronal and sagittal views were the most useful for demonstrating the rotator cuff. MR imaging has potential as a new non-invasive tool for the evaluation of the shoulder region.

Adult↗
PubMed1985

Nuclear magnetic resonance spectroscopy of rat ventricles following chronic hypoxia: a model of right ventricular hypertrophy.

Nuclear magnetic resonance spectroscopy was used to study the effect of chronic hypoxia on both right (RV) and left ventricular and septal (LV + S) muscle. Rats in the hypoxic group, kept in a hypobaric chamber at 1/2 atm pressure for 2 weeks, developed right, but not left, ventricular hypertrophy (p less than 0.001). Tissues were studied within 2.5 h of return to air. T1 and T2 relaxation times of RV, LV + S and thigh muscle (Th) from hypoxic and control rats were compared. The T2 value distinguished hypoxic from control RV (p less than 0.002), but not hypoxic from control LV + S or Th, indicating that the change in relaxation time reflects cellular hypertrophy, and not hypoxemia. For hypoxic rats only the T2 value distinguished each muscle type: RV from LV + S (p less than 0.009), RV from Th (p less than 0.001) and LV + S from Th (p less than 0001). The T1 value did not identify either the hypoxic or control group or the type of muscle. Percent water content was similar for all tissues. For hypoxic RV, T2 correlated with the percent water content (r = 0.89; p less than 0.01). The sensitivity of T2 to the cellular changes associated with hypoxic RV hypertrophy could provide a means of detecting right ventricular hypertrophy.

Animals↗
PubMed1985

The detection of inflammation in collapsed lung by alterations in proton nuclear magnetic relaxation times.

The purpose of this study was to establish the proton NMR relaxation times of collapsed but otherwise normal lung tissue and to determine whether an inflammatory process within a collapsed lung can be detected by alterations in relaxation times. The lungs of three groups of rabbits were studied: group A (n = 7) had a sterile collapse of one lung for two days. The two other groups also had one lung collapsed, but with bacterial (group B, n = 6) or chemically induced (group C; n = 6) pneumonitis superimposed. The contralateral lung, which was acutely deflated at the time of thoracotomy, served as a control in each animal. T1, T2 and the total water content were measured on freshly excised lung samples. In group A, there was no significant difference in T1 (606 +/- 14* ms vs. 595 +/- 18 ms;* = SEM) or T2 (80.6 +/- 1.7 ms vs. 78.4 +/- 2.6 ms) between the collapsed and the control lung tissue. In each animal in groups B and C, T2 was longer in the collapsed lung with superimposed pneumonitis than in the control lung tissue (group B: 116.8 +/- 6.9 ms vs. 82.9 +/- 1.8 ms, P less than .001; group C: 120.5 +/- 5.9 ms vs. 86.0 +/- 1.5 ms, P less than .001). T1 changes were similar, but less marked. There was a linear relationship between the relaxation times and the total water content of the lung samples (T1:r = 0.87; T2:r = 0.91). It is concluded that proton NMR may have a potential in detecting disease such as inflammation in collapsed lung tissue based on differences in relaxation parameters compared with normal lung areas.

Animals↗
PubMed1985

The detection of cardiac allograft rejection by alterations in proton NMR relaxation times.

The ability of proton NMR relaxation times to detect cardiac allograft rejection was studied in an inbred rat heterotopic cardiac transplantation model. Hearts from 25 Lewis X Brown Norway F1 hybrid rats were anastomosed to the abdominal aorta and vena cava of Lewis recipients; 25 Lewis donor hearts served as isograft controls. Groups of five allografts and five isografts were harvested daily between two and six days post-transplant. The relaxation times T1 and T2 of the transplanted hearts were determined in vitro with a 10 MHz spectrometer. T1 and T2 values in allografts did not differ significantly from those in isografts at days 2 and 3 post-transplant. However, at days 4, 5, and 6 T1 and T2 of the allografts were significantly prolonged. This finding correlated with an elevation in tissue water content and the onset of rejection as determined histologically. An additional 21 allografts, treated with cyclosporine, were studied in the same way from four to more than 100 days post-transplant. T1 and T2 values of these treated allografts did not change significantly during the observation period and were similar to the relaxation values obtained in the isografts at days 2 to 6. These data suggest that serial measurements of myocardial T1 and T2 may be useful in detecting acute cardiac allograft rejection and monitoring the effect of antirejection treatment.

Animals↗
PubMed1984

[Puerperal thrombophlebitis of the ovarian veins--diagnosis using CT].

Two cases of puerperal thrombophlebitis of the ovarian veins are described and the literature is reviewed. By means of computer tomography, it has become possible for the first time to make the diagnosis of this little-known and frequently missed condition by a non-invasive method. The patient is spared complicated angiographic procedures and possibly also surgery. The typical CT findings consist of: a) a thickened adnexa, b) a circular lesion extending from the adnexa to the hilum of the kidney, c) an obstructed ureter and c) an enlarged uterus.

Adult↗
PubMed1984

In vitro characterization of tomato fruit softening : the use of enzymically active cell walls.

Cell wall isolated from pericarp of normal tomato (Lycopersicon esculentum Mill. cv ;Rutgers') fruit released pectic polymers in a reaction apparently mediated by wall-bound polygalacturonase that appears with the onset of ripening. Release was negligible in wall preparations from normal green and the ripening mutant rin fruit. Pectin solubilization was most extensive at pH 2.5 with a less significant peak at 5.5. Brief exposure to low (1.5) or high (7.5) pH resulted in reduction of autolytic activity, which was also inhibited by high temperature, Ca(2+), and treatments employed to dissociate protein from cell wall. Uronic acid solubilization was significantly enhanced by 150 millimolar NaCl and by increasing temperature within the physiological range. These data indicate that the release of polyuronide from isolated cell walls is enzymic and may provide a convenient and reliable system for the study of softening metabolism.

Journal Article↗
PubMed1981

In vivo evaluation of experimental myocardial infarcts by ungated computed tomography.

The potential of ungated computed tomography (CT) to detect and quantify myocardial infarctions was assessed in 10 dogs. Twenty-seven in vivo CT examinations were performed at various time intervals (1 hr-20 days) after coronary artery occlusion. After intravenous contrast administration, CT delineated the infarcted myocardium in all 27 studies. The CT-determined infarct volume before sacrifice was closely correlated (r = 0.98) with the postmortem infarct weight. Delayed accumulation of iodinated contrast material in the infarct was seen in all 22 examinations performed 3 1/2 hr or longer postocclusion. The dynamics of contrast material accumulation and disappearance from normal and ischemic myocardium were also assessed. Presently available CT scanning without gating can noninvasively detect and quantify myocardial infarctions of various sizes and ages in living animals and can evaluate contrast dynamics whose time course is greater than a single circulation time.

Animals↗
PubMed1980

beta-d-Glucan Hydrolase Activity in Zea Coleoptile Cell Walls.

Enzymes dissociated from corn (hybrid B73 x Mo17) seedling cell walls by solutions of high ionic strength possess the capacity to degrade Avena caryopsis glucan. Inhibitor studies disclosed that both endo- and exoenzyme activities were involved and that the reaction sequence paralleled the autolytic solubilization of beta-d-glucan in isolated cell walls.The salt-dissociated exoenzyme activity was strongly inhibited by HgCl(2) and to a lesser extent by parachloromercuribenzoate at a concentration of 100 micromolar. In the absence of these inhibitors, Avena caryopsis glucan was converted to monosaccharide, whereas in the presence of the mercurials, only endoenzyme activity was apparent and the glucan substrate was hydrolyzed yielding products with an average molecular size of 1.5 to 3.0 x 10(4) daltons. Endoenzyme hydrolysis of the caryopsis glucan could not be attributed to the participation of an enzyme specific for mixed-linkage substrates.The autolytic capacity of isolated cell walls was similarly affected by inhibitors. In the presence of 100 micromolar HgCl(2), cell walls released from 60 to 80 micrograms per milligram dry weight as polymeric glucan during a 24-hour period. Monosaccharide accounted for less than 2% of the autolytically solubilized products. Analysis of the polymeric glucan product revealed a similarity in molecular size to the products obtained following treatment of Avena caryopsis glucan with salt-dissociated wall protein. The results suggest that among the salt-dissociated proteins are those responsible for the autolytic capacity of isolated cell walls.

Journal Article↗