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Biomedical subjects

J Coyle

Publications and source records attributed to J Coyle.

At least 19 recordsLinked to original sources
PubMed1995

Pfcrk-1, a developmentally regulated cdc2-related protein kinase of Plasmodium falciparum.

A gene encoding a novel cdc2-related protein kinase has been identified in Plasmodium falciparum, using degenerate oligonucleotides designed to hybridise to regions that are conserved in members of the cdc2 gene family. This gene, called Pfcrk-1, is located on chromosome 4. It is most closely related to the p58GTA gene family, members of which are negative regulators of cell growth in vertebrates. Pfcrk-1 is developmentally regulated, as indicated by stage-specific accumulation of mRNA in gametocytes.

Amino Acid Sequence↗
PubMed1990

Detection and measurement of simulated early rheumatoid lesions of the hand using digital subtraction radiography.

The ability of digital subtraction radiography, a new technique to detect and quantify small bone lesions, is demonstrated. Discrete lesions in the metacarpals of cadaver hands simulated erosive bone loss. Radiographs made before and after removal of bone were digitized and subtracted. Density changes on subtraction images were determined, and bone loss was estimated by an automatic procedure that compared changes in radiographic density with a calibration wedge included in the radiographs. Comparison of estimated bone loss with the weight of bone removed showed reproducible detection and measurement of bone lesions as small as 4.6 mg, a size undetectable using current radiographic methods. Subtraction radiographs of bone chips overlaid on the hand of a volunteer indicated detection limits were similar in vivo. This technique enhanced the radiographic visibility of erosive lesions and thus has the potential to improve the detection of subtle bone changes in clinical settings.

Arthritis, Rheumatoid↗
PubMed1989

Effect of local or systemic treatment prior to primary tumor removal on the production and response to a serum growth-stimulating factor in mice.

This report indicates that not only does the preoperative administration of cyclophosphamide or radiation prevent the kinetic changes observed in a distant tumor focus following tumor removal but that the preoperative administration of the antiestrogen tamoxifen and the luteinizing hormone-releasing hormone analogue Zoladex are equally effective in that regard. It also provides evidence indicating that serum obtained from mice treated with those therapies when transferred to a recipient bearing a tumor of a similar type to that in the donor fails to stimulate DNA synthesis in the tumor of the recipient. In contrast, an increase in labeling index occurs following transfer of serum obtained following tumor removal from untreated mice. Moreover, when tumor-bearing mice were treated by each of the four modalities prior to receiving serum obtained from untreated donors following removal of a tumor, no kinetic changes were observed in the tumor of the serum recipient.

Animals↗
PubMed1989

Presence of a growth-stimulating factor in serum following primary tumor removal in mice.

The effect of removal of a primary tumor on the kinetics of cells in a metastasis was evaluated using six different tumors (C3H, MXTa, MXTb, MC54, CD8, and 3LL) which varied relative to their origin, histology, and the strain of mice in which they were carried. There was an increase in the labeling index (LI) of distant tumor focus ("metastasis") associated with the removal of each of the tumor types and unrelated to operative and anesthetic trauma. Information presented supports the presence of a serum growth factor as being responsible for the phenomenon. Serum obtained from mice following removal of a tumor, when transferred to a recipient with the same type of tumor as in the donor, resulted in an increase in the LI of the tumor. Multiple injections of serum failed to add to the increase but did prolong its presence, suggesting that there is a finite population of cells, most likely in the G1-G0 phase, which are capable of responding to the stimulating factor. The transfer of serum obtained following removal of a tumor type different from that in recipients resulted in findings which indicate that tumors producing a stimulating growth factor are those capable of responding to it. Serum obtained from animals with unremoved tumors or less than 18 h after removal failed to substantially augment the LI of tumors in recipients. It is postulated that the growth factor released by a tumor is in an inactive form which becomes activated over time. Observations indicate that medium conditioned by the growth of C3H tumor contains a growth-stimulating factor which is capable of increasing the LI of a C3H tumor in a recipient in a fashion similar to that obtained following tumor removal. That finding indicates the capability of the tumor to elaborate growth-stimulating material which may be similar to that found in serum. The findings presented refute the premise that removal of a primary tumor is a local phenomenon with no other biological consequences. They indicate that, following primary tumor removal, metastatic behavior may be affected by an interplay of growth factor(s) which can influence the outcome of a host to its tumor.

Animals↗
PubMed1988

Cerebrospinal fluid correlates of depression in Huntington's disease.

Patients with Huntington's disease (HD) commonly have concomitant depressive disorders. Prompted by reports of elevated corticotropin releasing factor (CRF) and reduced 5-hydroxyindoleacetic acid (5-HIAA) concentrations in lumbar cerebrospinal fluid (CSF) of patients with major depression, these CSF constituents were examined in 56 nonmedicated patients who were in the early stages of HD. Elevated CRF concentrations were found in patients with HD in comparison with a control group of 21 subjects without neurologic illness. The CSF 5-HIAA concentrations in patients with HD did not differ from that in four normal volunteers. Patients with HD who had depressive disorders (major depression or dysthymia) did not differ from those without depression with respect to CSF 5-HIAA or CRF concentration. However, a positive correlation was observed between severity of major depression and CRF concentration. These findings suggest that the depression associated with HD may differ neurochemically from that seen in other major depressive disorders, and support the notion that clinically significant depressive symptoms reflect heterogeneous pathophysiologic conditions with different neurochemical correlates.

Adult↗
PubMed1988

Cerebrospinal fluid homovanillic acid and parkinsonism in Huntington's disease.

In Huntington's disease (HD), normal or decreased levels of homovanillic acid (HVA) in cerebrospinal fluid (CSF) have been reported but have not been analyzed with respect to severity of parkinsonism, which in certain cases may be a predominant feature of the illness. We obtained CSF by lumbar puncture from four groups of nonmedicated subjects: (1) those with HD in the earliest stages of illness (n = 51), (2) those with parkinsonism, including idiopathic (n = 10) and atypical forms (n = 4), (3) those with nonparkinsonian movement disorders (n = 19), and (4) normal volunteers (n = 4). HVA was determined by high-pressure liquid chromatography with electrochemical detection, and motor signs were assessed in standardized fashion. The parkinsonian group had reduced levels of CSF HVA, but the other groups showed no significant differences. For those with HD, no correlation was found between HVA level and severity of parkinsonism, and there were no differences in HVA level between those subjects with (n = 14) or without (n = 37) prominent parkinsonism or between subjects whose age at illness onset was 30 years or less (n = 16) and those whose age at onset was over 30 (n = 35). Our findings indicate that in early, untreated HD, CSF HVA is in the normal range and does not correlate with the severity of parkinsonism. This observation supports neuropathological findings suggesting that parkinsonian features in HD are largely related to the loss of postsynaptic striatal dopamine receptors rather than to presynaptic nigral degeneration.

Adult↗
PubMed1986

The effect of propranolol on catecholamine clearance.

Normal subjects given propranolol increased their plasma t1/2 for infused isoproterenol from 2.68 to 6.25 minutes. Propranolol increased plasma norepinephrine (NE) levels only slightly. Propranolol increased the t1/2 of isoproterenol but not that of NE in men with autonomic nervous system degeneration. This suggests that propranolol acts on nonneuronal uptake-2 processes, rather than on uptake-1 mechanisms. alpha-Blockers slow uptake-1 and beta-blockers slow uptake-2 processes. When 27 subjects exercised, those who attained the highest plasma levels of the alpha- and beta-receptor agonist NE also had the briefest apparent t1/2 for NE. Adrenergic receptor blocking drugs slow catecholamine clearance. NE may stimulate its own clearance.

Blood Pressure↗
PubMed1986

Interpretation of pulmonary artery wedge pressure and pullback blood gas determinations during positive end-expiratory pressure ventilation and after exclusion of the bronchial circulation in the dog.

Left atrial pressure (LAP) and pulmonary artery wedge pressure (PWP) were measured at different heights during graded increases in positive end-expiratory pressure (PEEP). Six healthy anesthetized dogs were placed in lateral decubitus positions with a balloon-tipped pulmonary artery catheter inserted in each lung. PWP in the gravitationally superior lung overestimated LAP at 15 and at 20 cm H2O PEEP (p less than 0.05). PWP in the dependent lung was virtually identical to LAP at all degrees of PEEP. Wedge blood could be aspirated through the distal lumen of the pulmonary artery catheters during balloon inflation at all degrees of PEEP except for 3 attempts. PCO2 in wedge blood in both the nondependent and dependent lungs at all degrees of PEEP was consistently lower than PCO2 in arterial blood (p less than 0.05). Wedge blood was arterialized, i.e., oxygen saturation greater than 95%, in all but 4 specimens. Surgical elimination of the bronchial artery supply to the lung in 3 dogs did not affect PWP or blood gas measurements. We conclude that in this animal model: (1) the tip of a pulmonary artery catheter must be below the level of the left atrium, Zone III location, to accurately reflect LAP at high degrees of PEEP; (2) arterialization of wedge blood samples does not guarantee that PWP reflects LAP; (3) bronchial artery blood supply does not affect PWP or wedge blood gas measurements, even at high degrees of PEEP.

Animals↗
PubMed1986

Relapse in chronic schizophrenics treated with fluphenazine decanoate is associated with low serum neuroleptic levels.

Seventy-three chronic schizophrenic outpatients were studied for 1 year to determine if neuroleptic drug levels could be useful in preventing relapse. All patients received fluphenazine decanoate i.m., and serum level of neuroleptic was determined by radioreceptorassay. Clinical improvement was measured using the Global Assessment Scale. Results indicate that serum neuroleptic drug levels may be useful in the outpatient management of chronic schizophrenics.

Adolescent↗
PubMed1985

Dipeptides of glutamate and aspartate may be endogenous neuroexcitants in the rat hippocampal slice.

The dipeptide N-acetylaspartylglutamate (NAAG), and possibly the related dipeptide aspartylglutamate (AG), have been found in high concentrations in rat brain, and have been shown to bind avidly and selectively to a subset of glutamate (GLUT) receptors. Certain observations regarding GLUT and aspartate might be explained if the endogenous transmitter were a compound composed of both amino acids. We therefore examined the electrophysiological actions of NAAG and AG in the rat in vitro rat hippocampal slice model. NAAG or AG and GLUT were applied locally to cells by a dual-barrel pressure technique. Intracellular recordings from 34 CA1 pyramidal neurons showed depolarizations and conductance increases resembling evoked excitatory postsynaptic potential in 15 of 20 cells exposed to NAAG, and 14 of 14 exposed to AG. Many GLUT-responsive sites did not respond to AG, and most did not respond to NAAG. Responses to NAAG were usually too small to induce cell firing; they were best detected, therefore, by intracellular recording. With extracellular unit recordings, GLUT was equally excitatory in stratum radiatum and pyramidale of CA1 (N = 19; p greater than 0.10, one-way analysis of variance). In contrast, AG was considerably more potent (N = 21; p less than 0.01) in stratum radiatum. NAAG was not noted to excite cells when applied to stratum pyramidale. The region of maximal responsiveness to AG in CA1 coincided with the area of the dendritic tree receiving Schaffer collateral-commissural afferents. This spatial profile, together with other neuropharmacological evidence, support the candidacy of glutamate-containing peptides as endogenous excitatory compounds in certain pathways of hippocampus.

Animals↗
PubMed1984

DNA polymerase alpha inhibition by aphidicolin induces gaps and breaks at common fragile sites in human chromosomes.

Aphidicolin, a specific inhibitor of DNA polymerase alpha, is known to induce chromosomal aberrations. At concentrations that did not greatly affect mitotic index, aphidicolin induced a striking number of chromosome gaps and breaks distributed in a highly nonrandom manner in cultured human lymphocytes. Specific chromosome bands, especially 2q31, 3p14, 6q26, 7q32, 16q23, and Xp22 were preferentially damaged in lymphocytes from each of 12 subjects studied. Total and site-specific damage was dose dependent and greatly increased when folic acid was removed from the medium. The sites most sensitive to aphidicolin damage include the "hot spots" seen under conditions of thymidylate stress and in studies of spontaneous chromosomal damage. The fragile X site, which can also be induced by thymidylate stress, was not induced by aphidicolin in lymphocytes, suggesting a separate mechanism for its induction. Aphidicolin represents a novel tool for detection of hot spots on human chromosomes through the mechanism of DNA polymerase alpha inhibition. The hot spots induced by aphidicolin represent a new class of fragile sites which we term common fragile sites.

Aphidicolin↗
PubMed1984

Serum neuroleptic concentrations and clinical response: a radioreceptor assay investigation of acutely psychotic patients.

Twenty-two acutely psychotic patients were rigorously assessed for psychopathology at baseline and after 14 days of neuroleptic treatment. The neuroleptic radioreceptor assay (NRRA) was used to determine serum neuroleptic concentrations. Serum neuroleptic concentration was significantly, nonlinearly related to changes in BPRS Total Score, and BPRS Factor Scores for Thought Disturbance and Anxiety-Depression. Clinical improvement was associated with intermediate (11-50, 51-126 ng/ml haloperidol equivalents) while poor clinical outcome was related to both low (less than or equal to 10 ng/ml) or high (greater than 125 ng/ml) serum levels. The results are discussed in terms of a possible "therapeutic window" for the neuroleptics and the implications this might have for clinical practice.

Adolescent↗
PubMed1983

Neuroleptic malignant syndrome: successful treatment with dantrolene and bromocriptine.

A patient with chronic schizophrenia treated with fluphenazine developed neuroleptic malignant syndrome, characterized by fever, obtundation, rigidity, and tremulousness. Hyperthermia and elevated serum creatine kinase were successfully corrected by parenteral treatment with dantrolene. Obtundation, rigidity, and tremulousness responded to high doses of bromocriptine.

Adult↗
PubMed1983

Fenfluramine lowers plasma norepinephrine in overweight subjects.

The effect of fenfluramine on sympathetic nervous system activity was determined in 12 normotensive, obese men. Supine plasma norepinephrine (NE) concentrations decreased (p less than 0.001) from pretherapy levels (298 +/- 39 pg/ml) after one (166 +/- 30 pg/ml) and four weeks (171 +/- 28 pg/ml) of fenfluramine (60 mg daily). Fenfluramine did not alter the sympathetic nervous system responses to orthostasis or exercise. Fenfluramine-induced decreases in heart rate (72 +/- 3 to 67 +/- 4 beats/min, p less than 0.01) and mean arterial blood pressure (90 +/- 2 to 81 +/- 2 mmHg; p less than 0.005) were observed after only one week of therapy despite no significant change in body weight. We conclude that fenfluramine may be a useful agent in the treatment of patients with sympathetic hyperactivity. The effects of fenfluramine on given subsets of patients and control subjects are also defined.

Adult↗
PubMed1982

Effects of premature depolarization on refractoriness of ischemic canine myocardium.

In 25 pentobarbital anesthetized dogs we measured refractory periods (RPs) of regularly driven complexes and premature ventricular depolarizations (PVDs) with a range of coupling intervals or of regularly driven complexes and the complex following the PVD, i.e. the postextrasystolic depolarization (PED). Measurements were made during control periods and during occlusion of a branch of the left anterior descending coronary artery. The difference in control and occlusion RPs was less following some PVDs with short coupling intervals than following other PVDs with longer coupling intervals. Variations in the coupling interval of PVDs had less effect on RPs of the PVDs in ischemic than in nonischemic tissue. RPs of PEDs were prolonged with respect to RPs of regularly driven complexes in both ischemic and nonischemic tissue, but the prolongation in ischemic tissue was significantly greater than that in nonischemic tissue, 8 +/- 4 msec and 2 +/- 2 msec respectively, p less than .001. The difference in effect of PVDs on RPs of ischemic and nonischemic tissue results in greater disparity of refractoriness between ischemic and nonischemic tissue following some long coupling interval PVDs than following some PVDs with shorter coupling intervals. In addition the greater prolongation of RPs of PEDs in ischemic than in nonischemic tissue can result in increased disparity in RPs than the disparity between ischemic and nonischemic tissue present during regular drive.

Animals↗
PubMed1982

Plasma, urine, and CSF catecholamine concentrations during and after ketamine anesthesia.

Ketamine has been reported to increase plasma catecholamine concentrations. Prior investigations have only studied plasma catecholamine levels for short periods after iv ketamine. Because ketamine is one of the most frequently used anesthetic agents in critical care research, we evaluated ketamine's effect on catecholamines over a longer period of time. Plasma, urine, and CSF epinephrine (E) and norepinephrine (NE) concentrations were serially measured during a 2-h ketamine infusion and a subsequent 2-h "wake-up" period. No changes in heart rate, mean arterial blood pressure or urine, plasma, and CSF NE concentrations were noted during the 4-h study period, whereas there were significant (p less than 0.005) increases in urine, plasma, and CSF E levels during ketamine infusion but not during the wake-up period. An unexpected finding was that the baboons have very high basal plasma E levels versus those in humans. It is concluded that ketamine is a useful anesthetic agent for critical care research involving measurements of sympathetic nervous system activity. The interesting observation of high plasma levels in the baboon warrants further investigation.

Anesthesia↗