Biomedical subjects

J Frye

Publications and source records attributed to J Frye.

At least 19 recordsLinked to original sources

PubMed1992

Progressive albuminuria and glomerulosclerosis in a rat model of chronic renal allograft rejection.

A significant proportion of renal allografts fail within several months or years after transplantation, primarily because of chronic rejection. The etiology and pathophysiology of this condition remain unclear. We studied the renal function, morphology, and immunohistology, in parallel, among F344-to-Lewis allografts (n = 23) and isografts (n = 13) over the course of 24 weeks. Only an initial 10-day course of CsA (5 mg/kg/day) was given to both groups to prevent acute rejection. Hypertension did not develop, although awake systolic blood pressure was significantly higher in allografts at the end of the study. Significant differences in urine albumin excretion (UalbV) between isografts and allografts were evident as early as 4 weeks after engraftment but rose dramatically by 20 weeks (3.3 +/- 0.7 vs. 21.2 +/- 3.7 mg/day, respectively, P < .001). This pattern continued until the conclusion of the study (5.0 +/- 1.1 vs. 53.5 +/- 7.6 mg/day, P < .001). Serum creatinine values were only significantly elevated in allografts at 16 weeks, which temporally corresponded to the dramatic increase in UalbV. However, renal blood flow and glomerular filtration rate, measured by paraaminohippurate and inulin clearances, respectively, were significantly lower in allografted organs, at 24 weeks. The frequency of glomerulosclerosis lesions was significantly increased in allografted kidneys at 24 weeks and correlated with UalbV values. Glomerular localization of mononuclear leukocyte subsets were equivalent between allografts and isografts; however, the numbers of interstitial macrophages, CD8+, and pan-T-cells were all significantly greater in allografts at 24 weeks. The infiltration of significantly greater numbers of macrophages and lymphocytes into the tubulointerstitium of the allograft group suggests a mononuclear leukocyte effector cell mediation of the progressive glomerular abnormalities in this model of chronic renal allograft rejection in the rat.

Albuminuria↗

PubMed1992

Macrophages mediate adverse effects of cholesterol feeding in experimental nephrosis.

We tested whether the deleterious effects of hypercholesterolemia, in a progressive glomerular disease model, may be mediated by infiltrating renal macrophages. A single sublethal dose of whole body X-irradiation (XI) delivered to rats with acute puromycin aminonucleoside (PA) nephrosis fed a high-cholesterol (HC) diet resulted in significantly greater inulin and p-aminohippurate (PAH) clearances at 11 days after PA without any alterations in circulating lipid levels, in contrast to nonirradiated HC-fed nephrotic controls. This functional protection was associated with significant declines in both glomerular and cortical interstitial macrophage number. Over the course of this 16-wk model, HC-fed PA rats had significantly less albuminuria as well as significantly fewer glomerulosclerosis (GS) lesions and less mesangial matrix expansion at the end of the study despite an equivalent degree of sustained hypercholesterolemia. This data suggests that reducing the infiltrating glomerular and cortical interstitial macrophage burden with XI during acute PA nephrosis, unaccompanied by any hypolipidemic effect, produces not only early salutary effects on renal function but also a significant amelioration of the progressive glomerulopathic features of this model. This is consistent with the hypothesis that the infiltrating renal macrophage, in large part, directly mediates the adverse effects of hypercholesterolemia in this model.

Acute Disease↗

PubMed1992

Glomerular macrophages and the mesangial proliferative response in the experimental nephrotic syndrome.

Mesangial cell proliferation, which is a harbinger of glomerulosclerosis, occurs in both immune and nonimmune glomerulopathies. The proximity of infiltrating glomerular macrophages to the contractile mesangial cells during acute puromycin aminonucleoside (PA) nephrosis suggests the possibility of a paracrine effect on mesangial cell growth. To test this, three maneuvers to either raise or lower the glomerular macrophage number during acute PA nephrosis (2 weeks after PA) were employed: 1) an essential fatty acid-deficient (EFAD) diet; 2) a cholesterol-supplemented diet (CSD); and 3) a single dose (600 rad) whole-body X-irradiation (XI) given to CSD-fed PA rats. Both the glomerular macrophage number and proliferation within the mesangium were evaluated immunohistochemically with ED-1, a mouse monoclonal anti-rat macrophage label, and 19A2, a mouse monoclonal anti-proliferating cell nuclear antigen (PCNA)/cyclin antibody, respectively. Immunohistochemical detection of 5'-bromo-2'-deoxyuridine (BrdU) incorporation confirmed that proliferation was occurring within the mesangial zones. The EFAD diet significantly reduced both the glomerular macrophage and PCNA/cyclin-positive cell number at 2 weeks after PA with a positive correlation (r = 0.89, P < 0.05). The CSD maneuver significantly increased both the glomerular macrophage and PCNA/cyclin cell number with a strong degree of correlation (r = 0.95, P < 0.01). X-irradiation administered to CSD-fed PA rats significantly lowered both the glomerular macrophage and PCNA/cyclin-positive cell number at 2 weeks. In all groups, the glomerular tufts did not express muscle actin using HHF 35, a specific immunolabel, suggesting that the proliferation in this model is not related to direct mesangial cell injury. This study shows that maneuvers that modulate the glomerular macrophage number are also associated with corresponding changes in the number of proliferating cells within the mesangium, suggesting a paracrine growth stimulation by the infiltrating macrophage during acute PA nephrosis. The infiltrating glomerular macrophage may be an effector mechanism for the propagation of initial glomerular injury to glomerulosclerosis by augmenting mesangial cell proliferation early in the course of this nonimmune progressive glomerulopathy.

Animals↗

PubMed1991

China White epidemic: an eastern United States emergency department experience.

STUDY OBJECTIVE: The purpose of this study was to isolate significant clinical or demographic findings concerning overdose patients treated during a China White (3-methyl fentanyl) epidemic and compare them with data for all unintentional narcotic overdose patients during a 24-month period. DESIGN: We reviewed charts from 85,246 patient visits to our emergency department during the 24-month period of January 1987 through December 1988 to study this narcotic epidemic. Data from the Allegheny County Coroner's Office pertaining to unintentional drug overdose deaths that occurred during this same period also were reviewed. SETTING: The first outbreak of narcotic overdoses in the eastern United States involving China White occurred in Allegheny County, Pennsylvania, in 1988. TYPE OF PARTICIPANTS: Patients were included if they met the criteria of a suspected unintentional narcotic overdose, but excluded if they were not given naloxone. INTERVENTIONS: Emergency physicians became suspicious of China White use after an unusual increase in narcotic overdoses presenting to the ED coupled with "routine drug of abuse" screens negative for opiates despite dramatic patient responses to naloxone. In most of the cases in which specific testing was done, there were positive indicators of fentanyl derivatives. Investigations found China White present in street drugs and paraphernalia. MEASUREMENTS AND MAIN RESULTS: A cluster was defined as a time period with a statistically significant increase in overdoses over the expected number for an interval of equal length. Although there were no significant clinical differences in case presentation during the 24-month period, there was a statistically significant 13-fold increase in overdoses during the September through November 1988 cluster (mean, 13 vs 0.95 per month, P less than .001 by Wilcoxon rank-sum test). A dramatic increase in unintentional drug overdose deaths occurred in the county during this cluster. A total of 18 fentanyl-positive unintentional drug overdose deaths, predominantly male (89%) and black (56%), with an age range of 19 to 44 years (mean, 34.9 years), were reported by the county coroner (13 during the cluster). Narcotic overdoses and unintentional drug overdose deaths declined sharply with confiscation of a clandestine China White laboratory. CONCLUSIONS: China White was responsible for a dramatic rise in unintentional drug overdose deaths in Allegheny County in 1988. There were no significant clinical differences between China White overdose survivors and other unintentional narcotic overdose victims. Overdoses responsive to naloxone with inconsistent routine toxicologic screens may be due to a fentanyl analogue.

Adult↗

PubMed1990

Phosphorylation modulates keratin structure.

Bovine hoof keratin was shown to be a substrate for cAMP-dependent protein kinase using [gamma-32P]ATP. Natural-abundance cross-polarization (CP) MAS 13C NMR was used to examine the effect of phosphorylation on keratin structure. When short contact times were used, phosphorylation was shown to increase the number of residues in the motionally restricted portions of the protein; i.e., a portion(s) of the protein became more rigid upon phosphorylation. Circular dichroism (CD) spectra showed a spectral shape characteristic of alpha helix for this keratin. Phosphorylation of the keratin by cAMP-dependent protein kinase resulted in a CD spectrum with the same shape but of greater apparent intensity. This may have been the result of an increase in the alpha-helical content of the protein. These data showed that the structure of keratin changed significantly upon phosphorylation by cAMP-dependent protein kinase. The region of the keratin molecule most likely to be altering its structure was the end of the molecule, which was involved in the formation of, and intracellular attachment of, intermediate filaments. Therefore, these data suggested that cAMP-dependent phosphorylation may produce significant changes in the intracellular organization of intermediate filaments. When the keratin was phosphorylated using cold ATP, magic-angle spinning (MAS) 31P nuclear magnetic resonance (NMR) revealed two resonances arising from the phosphorylation sites on the keratin. The more shielded resonance was shown to arise from cAMP-dependent protein kinase phosphorylation. Static 31P NMR measurements suggested that at least two classes of cAMP-dependent sites existed with the same isotropic 31P chemical shift; one was considerably motionally restricted with respect to the other.

Animals↗

PubMed1990

Cholesterol dynamics in membranes.

Time-resolved fluorescence anisotropy of the sterol analogue, cholestatrienol, and 13C nuclear magnetic resonance (NMR) spin lattice relaxation time (T1c) measurements of [13C4] labeled cholesterol were exploited to determine the correlation times characterizing the major modes of motion of cholesterol in unsonicated phospholipid multilamellar liposomes. Two modes of motion were found to be important: (a) rotational diffusion and (b) time dependence of the orientation of the director for axial diffusion, or "wobble." From the time-resolved fluorescence anisotropy decays of cholestatrienol in egg phosphatidylcholine (PC) bilayers, a value for tau perpendicular, the correlation time for wobble, of 0.9 x 10(-9) s and a value for S perpendicular, the order parameter characterizing the same motion, of 0.45 s were calculated. Both tau perpendicular and S perpendicular were relatively insensitive to temperature and cholesterol content of the membranes. The T1c measurements of [13C4] labeled cholesterol did not provide a quantitative determination of tau parallel, the correlation time for axial diffusion. T1c from the lipid hydrocarbon chains suggested a value for tau perpendicular similar to that for cholesterol. Steady-state anisotropy measurements and time-resolved anisotropy measurements of cholestatrienol were used to probe sterol behavior in a variety of pure and mixed lipid multilamellar liposomes. Both the lipid headgroups and the lipid hydrocarbons chains contributed to the determination of the sterol environment in the membrane, as revealed by these fluorescence measurements. In particular, effects of the phosphatidylethanolamine (PE) headgroup and of multiple unsaturation in the lipid hydrocarbon chains were observed. However, while the steady-state anisotropy was sensitive to these factors, the time-resolved fluorescence analysis indicated that tau perpendicular was not strongly affected by the lipid composition of the membrane. S perpendicular may be increased by the presence of PE. Both steady-state anisotropy measurements and time-resolved anisotropy measurements of cholestatrienol were used to probe sterol behavior in three biological membranes: bovine rod outer segment (ROS) disk membranes, human erythrocyte plasma membranes, and light rabbit muscle sarcoplasmic reticulum membranes. In the ROS disk membranes the value for S perpendicular was marginally higher than in the PC membranes, perhaps reflecting the influence of PE. The dramatic difference noted was in the value for tau perpendicular. In both the ROS disk membranes and the erythrocyte membranes, tau perpendicular was one-third to one-fifth of tau perpendicular in the phospholipid bilayers. This result may reveal an influence of membrane proteins on sterol behavior.

Animals↗

PubMed1987

Effects of unsaturation on 2H-NMR quadrupole splittings and 13C-NMR relaxation in phospholipid bilayers.

Motional order and motional rates in unsonicated phospholipid bilayers were assessed as a function of unsaturation of the phospholipid. A measurement sensitive to motional order was obtained using 2H-NMR of 18:1, 18:1-phosphatidylcholine labelled at positions 9 and 10 with deuterium and included as a probe in phospholipid bilayers of interest at 10 mole percent. Spin lattice relaxation times from magic angle spinning 13C-NMR spectra of phospholipid dispersions of interest were used as a measure of motional rates. Measurements were made of phospholipid bilayers containing from 0 to 8 double bonds per molecule. No large effect of an increase in unsaturation was noted for the 2H-NMR quadrupole splittings or for the 13C-NMR spin lattice relaxation rate.

Carbon Isotopes↗

PubMed1985

The role of plasma lipids in carotid bifurcation atherosclerosis.

The severity of coronary artery atherosclerosis correlates with increased plasma concentrations of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and triglycerides and with decreased plasma concentrations of high-density lipoprotein cholesterol (HDL-C). The role of plasma lipoproteins in the pathogenesis of cerebral atherosclerosis, however, is less clear. Several investigators report that lipoprotein abnormalities correlate inversely with the incidence of cerebral infarction. We analyzed risk factors for carotid bifurcation atherosclerosis in 121 consecutive patients who underwent cerebral angiography. This analysis revealed a significant positive correlation between the plasma TC/HDL-C ratio and the extent of carotid bifurcation atherosclerosis (p = 0.01). The extent of atherosclerosis correlated inversely with plasma concentrations of HDL-C (p = 0.02). Triglyceride concentration correlated positively with the extent of atherosclerosis with marginal significance (p = 0.07). LDL-C and TC concentrations did not correlate with bifurcation atherosclerosis (p greater than 0.1). Only 4% of the variation in the extent of bifurcation atherosclerosis was explicable on the basis of plasma lipoprotein concentrations.

Aged↗

PubMed1985

Analysis of solid-state Carbon-13 NMR spectra of polymorphs (benoxaprofen and nabilone) and pseudopolymorphs (cefazolin).

The solid-state 13C-NMR spectra of the polymorphs of benoxaprofen, nabilone, and cefazolin are reported using the cross-polarization/magic-angle spinning (CP/MAS) technique. In general, the spectra of the different crystal forms are different. In favorable cases the spectra of the drug in a pharmaceutical granulation can be discerned. These results provide a preliminary indication that solid-state NMR spectroscopy is a useful technique for the investigation of drug polymorphs and drugs in their dosage forms.

Anti-Inflammatory Agents↗

PubMed1985

Cross polarization P-31 nuclear magnetic resonance of phospholipids.

P-31 single-pulse and cross-polarization (CP) nuclear magnetic resonance spectra were obtained of aqueous dispersions of pure phospholipids. Dimyristoyl phosphatidylcholine, dipalmitoylphosphatidylcholine, 1-palmitoyl-2-oleoyl phosphatidylcholine, egg phosphatidylcholine, bovine brain sphingomyelin, and transphosphatidylated (from egg phosphatidylcholine) phosphatidylethanolamine were studied. The spectra from all the phospholipids, taken in the usual single-pulse mode, showed the pseudo-axially symmetric powder pattern typical of phospholipids in a hydrated lamellar form. P-31 CP spectra of all the phosphatidylcholines and phosphatidylethanolamine revealed a decrease in intensity in the vicinity of the isotropic chemical shift as long as the lipid was above the gel-to-liquid crystalline phase transition temperature. This intensity pattern has been observed previously for C-13 CP spectra of molecules rotating rapidly about a single well-defined axis (e.g., solid benzene) (Pines, A., M.G. Gibby, and J.S. Waugh, 1973, J. Chem. Phys., 59:569-590). Pure lipid dispersions below their gel-to-liquid crystalline phase transition temperature, including dipalmitoylphosphatidylcholine and sphingomyelin, do not exhibit a local minimum in the CP spectrum at the position of the isotropic chemical shift. Thus, below the phase transition temperature, there is not the same rapid rotation of the headgroup about a well-defined axis. A dramatic change in the rate of headgroup rotation is shown to take place at the pretransition of dipalmitoylphosphatidylcholine. P-31 CP spectra were also obtained for bovine rod outer segment disk membranes, rabbit muscle sarcoplasmic reticulum membranes, a total lipid extract of the latter, and a recombined membrane containing human erythrocyte glycophorin. The CP spectra were similar to the single-pulse spectra, indicating a substantial difference in behavior from pure phospholipid dispersions. This is interpreted in terms of a slower headgroup rotation.

Animals↗

PubMed1973

Serial thalamic lesions and tactile discrimination in the rat.

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Animals↗

PubMed1973

Changes in surface morphology of Chinese hamster ovary cells during the cell cycle.

Synchronized populations of Chinese hamster ovary (CHO) cells in confluent culture have been examined by scanning electron microscopy and their surface changes noted as the cells progress through the cycle. During G(1) it is characteristic for cells to show large numbers of microvilli, blebs, and ruffles. Except for the ruffles, these tend to diminish in prominence during S and the cells become relatively smooth as they spread thinly over the substrate. During G(2) microvilli increase in number and the cells thicken in anticipation of rounding up for mitosis. It appears that the changes observed here reflect the changing capacity of CHO cells during the cycle to respond to contact with other cells in the population, because, as noted in the succeeding paper (Rubin and Everhart), CHO cells in sparse nonconfluent cultures do not show the same wide range of changes during the cell cycle. Normal, nontransformed cells of equivalent type in confluent culture are essentially devoid of microvilli, blebs, and ruffles. The relation of these surface configurations to the internal structure of the cell is discussed.

Animals↗

PubMed1972