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Biomedical subjects

M L Gross

Publications and source records attributed to M L Gross.

At least 127 records · Page 7Linked to original sources
PubMed1986

Effect of captopril on 99mTc-diethylenetriaminepentaacetic acid renograms in two-kidney, one clip hypertension.

In an effort to improve on the noninvasive detection of renal artery stenosis, we investigated the effect of angiotensin converting enzyme inhibition on computer-assisted 99mTc-diethylenetriaminepentaacetic acid (DTPA) renal flow studies in a canine model of two-kidney, one clip hypertension and compared these findings with clearances of inulin and p-aminohippuric acid in the stenotic and contralateral kidney before and after converting enzyme inhibition. The 99mTc-DTPA renal flow study with the converting enzyme inhibitor captopril (1.5 mg/kg bolus with 1.5 mg/min infusion) showed an increased sensitivity in the detection of unilateral renal artery stenosis over the use of the 99mTc-DTPA study alone. Captopril induced striking alterations that were most evident in the 15-minute 99mTc-DTPA renal flow study, in which all nine curves exhibited severely blunted uptake and excretion of the radionuclide. These changes were reversed during a recovery study without converting enzyme inhibition and were not seen when blood pressure was lowered with nitroprusside to a level similar to that observed during converting enzyme inhibition. The changes shown by the 99mTc-DTPA study during converting enzyme inhibition correlated with a decrease in the glomerular filtration rate of the stenotic kidney. Captopril infusion significantly decreased the glomerular filtration rate of the stenotic kidney (16.0 +/- 3.1 vs 11.0 +/- 2.5 mg/min, p less than 0.03) but not of the contralateral kidney (32.4 +/- 2.6 vs 28.4 +/- 2.8 mg/min).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Effects of glucocorticoids on experimental allergic neuritis.

Corticosteroids were administered to rats and guinea pigs with experimental allergic neuritis, from the time of inoculation with antigen or from the onset of signs of disease. No statistically significant effects were observed in guinea pigs. In rats, to which large doses of corticosteroids were administered, disease severity was slightly but significantly reduced in both groups and recovery was more rapid in the animals treated from the time of induction of disease. These results were comparable with those obtained in trials of corticosteroids in acute inflammatory polyneuropathy in man, which have also not demonstrated any striking effects.

Animals↗
PubMed1985

Technetium-99m DTPA renal flow studies in Goldblatt hypertension.

Computer-assisted dynamic renal studies were performed on a group of 14 mongrel dogs before and after the induction of unilateral renal artery stenosis. Ninety-second technetium-99m diethylenetriaminepentaacetic acid ( [99mTc]DTPA), 15-min [99mTc]DTPA, and 30-min iodine-131 orthoiodohippurate ( [131I]hippuran) time-activity curves were analyzed and correlated with reduction of renal blood flow as measured by electromagnetic flow probe and PAH clearance techniques. Parameters of the 90-sec [99mTc]DTPA curves found to be significantly different for the same kidney before and after stenosis were: upslope, curve width at 75% maximum, maximum activity value, and differential (stenotic/contralateral) maximum activity ratio. For blood flow reductions greater than 33%, the [99mTc]DTPA studies were judged diagnostic of unilateral renal artery stenosis in all cases, whereas the [131I]hippuran time-activity curves were indicative of stenosis in only six of ten studies. Thus, in this model we find the computer-assisted 90-sec [99mTc]DTPA renal flow study to be superior to conventional [131I]hippuran renography in the diagnosis of moderate-to-severe unilateral renal artery stenosis.

Animals↗
PubMed1985

Improved computer-assisted nuclear imaging in renovascular hypertension.

Computer-assisted dynamic renal studies using both the 90 second 99mTc-DTPA and the conventional 30 minute 131I-Hippuran methods were performed in nine patients with angiographically proven renal artery stenosis. Time activity curves for both studies were derived from regions of interest selected from the computer-acquired dynamic images. The following parameters were used to assess renal blood flow: differential maximum activity, minimum/maximum activity ratio, and peak width. The computer-assisted DTPA study accurately predicted (9/9) the stenotic side documented angiographically, whereas the conventional Hippuran scan was clearly predictive in only 57% (5/9). The best discriminatory factors for the 90 second 99mTc-DTPA scan, when compared to a normal template synthesized from curves obtained from normal subjects (20), were differential maximum activity and peak width. In conclusion, the computer-assisted 90 second 99mTc-DTPA renal blood flow scan was superior to the conventional 30 minute 131I-Hippuran scan in demonstrating unilateral renovascular disease. The DTPA study was highly predictive of the angiographic findings, and this noninvasive study may prove useful in the diagnosis and serial evaluation following surgery or angioplasty in patients having renal artery stenosis.

Adult↗
PubMed1984

Fourier transform mass spectrometry.

Fourier transform mass spectrometry will play an important role in the future because of its unique combination of high mass resolution, high upper mass limit, and multichannel advantage. These features have already found application in gas chromatography-mass spectrometry, multiphoton ionization, laser desorption, and secondary ion mass spectrometry. However, its most notable feature is the ability to store ions. This characteristic, when combined with the others, will allow expeditious study of the interaction of gas-phase ions with both photons (photodissociation) and neutral molecules, and the convenient application of this fundamental information for chemical analysis.

Chemical Phenomena↗
PubMed1984

Fast atom bombardment combined with tandem mass spectrometry for the determination of nucleosides.

The positive and negative ion fast atom bombardment (FAB) mass spectra and fast atom bombardment collisionally activated decomposition (CAD) spectra of a series of nucleosides and two dinucleotides are reported. The nucleosides studied are substituted forms of guanosine, adenosine, nebularine, tubercidin, uridine, and related pyrimidines. The FAB and CAD data both contain similar information. The CAD spectra are found to provide some structural information not found in the FAB mass spectra. Tandem mass spectrometry also allows emphasis to be put on weak fragments which are either not observed in the FAB mass spectrum or are lost in the matrix ion signals.

Adenosine↗
PubMed1984

Ribosyl-diphthamide: confirmation of structure by fast atom bombardment mass spectrometry.

Diphtheria toxin inactivates protein synthesis elongation factor 2 by attaching ADP-ribose to an unusual post-translational amino acid derivative, diphthamide, in the factor. Previously, we prepared ribosyl-diphthamide from the ADP-ribosyl-factor and proposed on the basis of NMR spectral analysis that it is 1-alpha-D-ribofuranosyl-2-[3-carboxyamido-3-(trimethylammonio++ +)propyl] histidine [N. J. Oppenheimer, and J.W. Bodley, (1981) J. Biol. Chem. 256, 8579-8581 and op. cit.]. Now, using fast atom bombardment mass spectrometry, the intact cation of ribosyl-diphthamide has been observed in the gas phase. The theoretical mass of the structure proposed for ribosyl-diphthamide uniquely agrees with the observed mass of the inact cation of the compound to within 2 ppm. Collisional activation decomposition mass spectral analysis provided additional structural confirmation. Thus, although the compound has not been synthesized, all available evidence appears uniquely consistent with the structure of ribosyl-diphthamide previously proposed.

Chemical Phenomena↗
PubMed1984

2,3,7,8-Tetrachlorodibenzo-p-dioxin levels in adipose tissue of Vietnam veterans.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) has been detected at levels ranging from 20 to 173 parts per trillion in adipose tissue from three Vietnam veterans who were "heavily exposed" to Herbicide Orange. Some tissue samples from other Vietnam veterans and from controls also contained 2,3,7,8-TCDD at levels below 20 parts per trillion.

Adipose Tissue↗