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Biomedical subjects

J L Cooper

Publications and source records attributed to J L Cooper.

At least 19 recordsLinked to original sources
PubMed1999

Stumbling corrective responses in healthy human subjects to rapid reversal of treadmill direction.

The kinematics of stumbling and recovery induced by a rapidly reversing treadmill is described for eight healthy adults. Stability was achieved in approximately 400 ms following treadmill reversal (initiated at heel-strike) and the ensuing stumble. It appeared to be accomplished primarily by rapid flexion of the thigh and knee of the stance limb, which prevented damage to the knee joint and lowered the trunk, and by extension of the contralateral joints (swing limb), which contacted the ground presumably to deliver an impulsive thrust to counter the backward lean of the trunk. The movements of the ankle also contributed to the recovery from the stumble, but its movements were markedly more variable among the subjects than those of the thigh and knee. The observed kinematics to some extent resembled a crossed-extension reflex, which may have been triggered by muscle, joint, cutaneous or vestibular afferents. These data should provide a baseline by which to compare groups in which recovery from stumbling is known to be deficient (e.g., the elderly).

Accidental Falls↗
PubMed1999

Specialty care for patients with epilepsy must become standard of care. Promotion of Specialty Care for Epilepsy Group.

Epilepsy is a complex, common disorder with severe consequences for patients. The authors believe that a significant percentage of patients are receiving suboptimal care. The national standard of care needs to be upgraded to include the notion that patients with less than total seizure control or those suffering from any medication side-effects should be given the opportunity to receive specialty care by physicians with specific expertise in the field of epilepsy.

Epilepsy↗
PubMed1998

A surface measure for probabilistic structural computations.

Computing three-dimensional structures from sparse experimental constraints requires method for combining heterogeneous sources of information, such as distances, angles, and measures of total volume, shape, and surface. For some types of information, such as distances between atoms, numerous methods are available for computing structures that satisfy the provided constraints. It is more difficult, however, to use information about the degree to which an atom is on the surface or buried as a useful constraint during structure computations. Surface measures have been used as accept/reject criteria for previously computed structures, but this is not an efficient strategy. In this paper, we investigate the efficacy of applying a surface measure in the computation of molecular structure, using a method of probabilistic least square computations which facilitates the introduction of multiple, noisy, heterogeneous data sources. For this purpose, we introduce a simple purely geometrical measure of surface proximity called maximal conic view (MCV). MCV is efficiently computable and differentiable, and is hence well suited to driving a structural optimization method based, in part, on surface data. As an initial validation, we show that MCV correlates well with known measures for total exposed surface area. We use this measure in our experiments to show that information about surface proximity (derived from theory or experiment, for example) can be added to a set of distance measurements to increase significantly the quality of the computed structure. In particular, when 30 to 50 percent of all possible short-range distances are provided, the addition of surface information improves the quality of the computed structure (as measured by RMS fit) by as much as 80 percent. Our results demonstrate that knowledge of which atoms are on the surface and which are buried can be used as a powerful constraint in estimating molecular structure.

Animals↗
PubMed1994

Epidemiologic observations on infection with Rochalimaea species among cats living in Baltimore, Md.

Cats from several sources in Baltimore, Md, were tested for seropositivity to Rochalimaea henselae and R quintana. Co-infection with Toxoplasma gondii or feline immunodeficiency virus was assessed as a risk factor for infection with Rochalimaea spp. Of 592 cats tested, 87 (14.7%) were seropositive for one or both Rochalimaea spp, although titers to R henselae were significantly higher than those to R quintana. Prevalence of seropositivity increased significantly with cat age and weight and was associated with seropositivity to T gondii but was not associated with gender. Prevalence of seropositivity was similar (12.5 to 14.4%) among groups of cats with some history of human contact but was higher among feral cats (44.4%). Whether cats are reservoirs or mechanical vectors of Rochalimaea spp that can cause diseases in people is still uncertain, but these findings indicated widespread infection of cats and suggested possible modes of transmission for Rochalimaea spp among cats.

Age Factors↗
PubMed1994

Markers for pancreatic allograft rejection: comparison of serum anodal trypsinogen, serum amylase, serum creatinine and urinary amylase.

Currently, the markers of acute rejection in pancreas allografts are not consistently reliable. The purpose of this study was to evaluate the ability of sAT to predict acute rejection as compared to serum creatinine (sCr), urinary amylase (uAmy) and serum amylase (sAmy). Eleven first-time acute rejection episodes in bladder-drained SPK recipients were studied. All rejection episodes were biopsy-proven (core kidney 9, fine needle kidney 2, fine needle pancreas 5). Sera obtained from days -7 to -1 (pre-treatment), day 0 (start of anti-rejection treatment), and +1 to +7 (post-treatment) periods were analyzed. Peak median sAT and sAmy levels occurred at day 0 compared to day 1 for sCr. uAmy trough levels occurred on days -4, -5 and +2. The difference between pre-treatment levels and those on day 0 were significant for sAT, sAmy and sCr but not for uAmy. Only in the case of sAT was the difference between day 0 levels and post-treatment levels significant. Both sAmy (0.87) and sCr (0.85) demonstrated positive correlation when compared to sAT whereas uAmy demonstrated a weak negative correlation (-0.24). This study confirms that sAT accurately predicts rejection after SPK transplantation.

Amylases↗
PubMed1993

Contralateral ovary in unilateral ovarian carcinoma: a search for preneoplastic lesions.

Contralateral ovaries from patients with unilateral ovarian carcinoma were examined and compared to ovaries from age-matched control patients without ovarian carcinoma. The number of inclusion cysts were increased in ovaries from patients with ovarian carcinoma compared to the controls (p < 0.01). In addition, inclusions from cases with ovarian carcinoma showed serous differentiation more frequently than the controls (p < 0.01; odds ratio = 10.0; 95% confidence interval = 1.2-78.1). An age-related increase in the number of inclusion cysts was seen in the study group but not in the control group. These findings support a role of surface inclusion cysts in the genesis of ovarian carcinoma.

Adult↗
PubMed1993

Incidence, management and significance of surgical complications after pancreatic transplantation.

Despite recent advances, pancreatic transplantation is still in evolution and is associated with considerable surgical morbidity. We reviewed the surgical complications of 127 consecutive whole pancreatic transplants performed at the University of Iowa between March 1984 and January 1992, to evaluate the impact of these complications on graft and patient outcome. Of these transplantations, 89 were simultaneous pancreatic and renal transplants, 32 pancreas after kidney and six pancreas alone. Of all complications requiring hospital admission, 29 percent were surgical in nature. Graft thrombosis (19 percent), deep wound infection (18 percent), duodenal leak (7 percent) and iliac artery disruption (3 percent) were all associated with significant graft (n = 28) and patient (n = 6) loss. In contrast, recurrent urinary tract infections (20 percent), recurrent pancreatitis (17 percent), superficial wound infections (13 percent) and recurrent hematuria (12 percent) did not affect patient or graft outcome. Surgical complications after technically successful transplants were associated with a 4.9 percent mortality rate and a 4.9 percent graft loss. The overall one year actuarial patient and pancreas graft survival rate was 86 and 75 percent, respectively. Despite ongoing refinements in surgical technique, pancreatic transplantation is still associated with considerable surgical morbidity. However, the outcome is favorable if these complications are managed aggressively.

Abscess↗
PubMed1990

SV40 T antigen alone drives karyotype instability that precedes neoplastic transformation of human diploid fibroblasts.

To define the role of SV40 large T antigen in the transformation and immortalization of human cells, we have constructed a plasmid lacking most of the unique coding sequences of small t antigen as well as the SV40 origin of replication. The promoter for T antigen, which lies within the origin of replication, was deleted and replaced by the Rous sarcoma virus promoter. This minimal construct was co-electroporated into normal human fibroblasts of neonatal origin along with a plasmid containing the neomycin resistance gene (neo). Three G418-resistant, T antigen-positive clones were expanded and compared to three T antigen-positive clones that received the pSV3neo plasmid (capable of expressing large and small T proteins and having two origins of replication). Autonomous replication of plasmid DNA was observed in all three clones that received pSV3neo but not in any of the three origin minus clones. Immediately after clonal expansion, several parameters of neoplastic transformation were assayed. Low percentages of cells in T antigen-positive populations were anchorage independent or capable of forming colonies in 1% fetal bovine serum. The T antigen-positive clones generally exhibited an extended lifespan in culture but rarely became immortalized. Large numbers of dead cells were continually generated in all T antigen-positive, pre-crisis populations. Ninety-nine percent of all T antigen-positive cells had numerical or structural chromosome aberrations. Control cells that received the neo gene did not have an extended life span, did not have noticeable numbers of dead cells, and did not exhibit karyotype instability. We suggest that the role of T antigen protein in the transformation process is to generate genetic hypervariability, leading to various consequences including neoplastic transformation and cell death.

Antigens, Viral, Tumor↗
PubMed1989

The automation of routine calculations and graphing for alkaline filter elution analysis on a computer-controlled liquid scintillation analyzer.

The data calculations and graphing functions for the widely used alkaline filter elution technique have been completely automated. This saves considerable time and increases both efficiency and accuracy by eliminating human error. The automation was accomplished utilizing Lotus 1-2-3 and Lotus Graphwriter II on a Packard Tri-Carb 1900CA liquid scintillation analyzer containing a built-in pico-XTE computer. A batch file is used to control the overall execution of the process. It copies the data stored by the 1900CA into the Lotus subdirectory and invokes Lotus 1-2-3. A Lotus macro automatically imports the data file, performs the calculations, and prints the results. Graphwriter II is then invoked by the batch file and the charts are composed and graphed. Finally, the instrument operating software for the 1900CA is reentered and sample analysis can be resumed for any unanalyzed samples.

Alkalies↗
PubMed1988

Characterization of the rebinding of 125I-epidermal growth factor released from BALB/c-3T3 cells following accumulation in the presence of chloroquine.

Lysosomotropic amines, such as chloroquine and methylamine, increase the intracellular accumulation of 125I-EGF by inhibiting lysosomal degradation. It has been shown previously that BALB/c-3T3 cells, prelabeled at 4 degrees C with 125I-EGF for 3 h and subsequently chased at 37 degrees C in the presence of chloroquine, internalized the surface bound 125I-EGF which was subsequently released into the extracellular medium in a high molecular weight form which co-migrated with native 125I-EGF. The secreted 125I-EGF rebound to the cells from which it was released more efficiently than does peptide in the extracellular media. We now show that when the BALB/c-3T3 cells were prelabeled at 37 degrees C for 2 h in the presence of chloroquine, the internalized 125I-EGF released into the medium was in a high molecular weight form which co-migrated with native 125I-EGF and did not rebind anymore efficiently than did peptide in the extracellular media. This lack of rebinding was not due to an alteration in the 125I-EGF molecule since it was still capable of rebinding to naive A431 cells, nor was it due to the exhaustion of EGF receptors on the BALB/c-3T3 cells. The inhibition of rebinding was observed only when the cells were treated with EGF in the presence of chloroquine, and was not due to a general down-regulation of membrane receptors. The differences between the rebinding of 125I-EGF at 4 degrees C and 37 degrees C suggest that EGF may be processed via different pathways in the cell.

Animals↗
PubMed1987

Interaction between monensin and lysosomotropic amines in the regulation of the processing of epidermal growth factor by BALB/c 3T3 cells.

Monensin, like the lysosomotropic amines chloroquine and methylamine, caused a large accumulation of 125I-EGF in BALB/c-3T3 cells that was due to specific increases in the amount of intracellular intact hormone. However using a pulse-chase paradigm of 125I-EGF accumulation, marked differences were observed between monensin and the amines. When EGF was accumulated in the presence of monensin, there was a gradual loss of cell-bound radioactivity during a chase in the absence of the drug, and the labeled material recovered in the medium primarily consisted of degraded hormone. The continued presence of monensin in the chase medium substantively prevented the loss of cell bound material, and what little was recovered in the medium consisted of intact 125I-EGF. In contrast, when 125I-EGF was accumulated in the presence of methylamine, predominantly intact peptide was lost from the cells at a relatively high rate during the chase whether or not methylamine remained in the medium. When monensin was present in the chase medium following accumulation in the presence of either chloroquine or methylamine, the loss of intracellular 125I-EGF was essentially blocked.

Animals↗
PubMed1987

Orbital histiocytic lymphoma arising from the ethmoid sinus.

Histiocytic lymphoma has been reported previously as an orbital manifestation of systemic malignancy. We report herein a 49-year-old white male with orbital involvement from a sclerosing lesion in the ethmoid sinus that initially caused a biopsy-proven orbital inflammatory mass. This report of an orbito-sinus histiocytic lymphoma underscores the need to re-biopsy symptomatic orbital inflammatory lesions that continue to enlarge.

Biopsy↗
PubMed1986

Effects of phenothiazines on binding and processing of epidermal growth factor in 3T3 cells.

Chlorpromazine (CPZ) or the functionally related N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide caused a rapid decrease in binding of 125I-epidermal growth factor (EGF) that was due to a specific decrease in receptor affinity. The decrease in ligand binding was observed when cells were exposed to CPZ at either 4 degrees C or 37 degrees C but a rapid reversal of CPZs effects was observed only during a 37 degrees C incubation. In contrast to the decrease in 125I-EGF binding seen after short (30 min) accumulations at 37 degrees C, the presence of CPZ caused a large increase in the amount of cell-associated radioactivity after longer periods (over 1 h) of accumulation. Although the CPZ-induced effect was similar in extent to that observed after the addition of methylamine, the increased accumulation after CPZ was probably not due to a nonspecific ionic neutralization of the lysosomes. CPZ did not lower EGF binding in cultures chronically treated with a phorbol ester to reduce protein kinase C levels, although the CPZ-induced increases in accumulation were still observed in cells with reduced protein kinase C activity.

Animals↗