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Biomedical subjects

D Lawrence

Publications and source records attributed to D Lawrence.

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

Cloning and sequence of a cDNA coding for the human beta-migrating endothelial-cell-type plasminogen activator inhibitor.

A lambda gt11 expression library containing cDNA inserts prepared from human placental mRNA was screened immunologically using an antibody probe developed against the beta-migrating plasminogen activator inhibitor (beta-PAI) purified from cultured bovine aortic endothelial cells. Thirty-four positive clones were isolated after screening 7 X 10(5) phages. Three clones (lambda 1.2, lambda 3, and lambda 9.2) were randomly picked and further characterized. These contained inserts 1.9, 3.0, and 1.9 kilobases (kb) long, respectively. Escherichia coli lysogenic for lambda 9.2, but not for lambda gt11, produced a fusion protein of 180 kDa that was recognized by affinity-purified antibodies against the bovine aortic endothelial cell beta-PAI and had beta-PAI activity when analyzed by reverse fibrin autography. The largest cDNA insert was sequenced and shown to be 2944 base pairs (bp) long. It has a large 3' untranslated region [1788 bp, excluding the poly(A) tail] and contains the entire coding region of the mature protein but lacks the initiation codon and part of the signal peptide coding region at the 5' terminus. The two clones carrying the 1.9-kb cDNA inserts were partially sequenced and shown to be identical to the 3.0-kb cDNA except that they were truncated, lacking much of the 3' untranslated region. Blot hybridization analysis of electrophoretically fractionated RNA from the human fibrosarcoma cell line HT-1080 was performed using the 3.0-kb cDNA as hybridization probe. Two distinct transcripts, 2.2 and 3.0 kb, were detected, suggesting that the 1.9-kb cDNA may have been copied from the shorter RNA transcript. The amino acid sequence deduced from the cDNA was aligned with the NH2-terminal sequence of the human beta-PAI. Based on this alignment, the mature human beta-PAI is 379 amino acids long and contains an NH2-terminal valine. The deduced amino acid sequence has extensive (30%) homology with alpha 1-antitrypsin and antithrombin III, indicating that the beta-PAI is a member of the serine proteinase inhibitor (serpin) superfamily.

Amino Acid Sequence↗
PubMed1986

Two-dimensional gel electrophoresis of endometrial protein in human uterine fluids: qualitative and quantitative analysis.

By combining two-dimensional gel electrophoresis, protein staining and a sensitive computer-assisted gel scanning system, it was possible to examine human uterine fluid (n = 56) qualitatively and quantitatively for the presence of endometrial proteins. The protein concentration of uterine fluids ranged from 0.1 to 12.0 mg/ml with early secretory phase samples (n = 15) having significantly less protein (0.72 +/- 0.2 SEM mg/ml p less than or equal to 0.05) than the proliferative phase (n = 57) samples (1.58 +/- .29 SEM mg/ml). Whole blood contamination of uterine fluid, as measured by hemoglobin content, averaged 6.2 +/- 0.88% throughout the menstrual cycle. Human uterine fluids collected throughout the menstrual cycle were found to contain serum and up to 24 other proteins in addition to those previously described (MacLaughlin and Richardson, 1983). These proteins represent approximately 1% of the total protein in the gels and exhibit isoelectric points from 4.5 to 7.0 and molecular weights in the 26,000 to 60,000 range. These proteins are absent from human serum, which exhibits an identical pattern whether obtained in the proliferative or secretory phase of the menstrual cycle. These secreted endometrial proteins now become the standard against which to compare proteins identified in vitro using organ, gland and cell culture techniques and to characterize proteins that are regulated by steroid hormones in vivo.

Body Fluids↗
PubMed1985

Hemodynamic and clinical assessment after therapy for acute deep vein thrombosis. A prospective study.

This prospective study was undertaken in 153 patients who had sustained DVT of various extents and had been treated with streptokinase or heparin. Its aim was (1) to assess hemodynamic changes occurring in the deep venous system over a 2 year period, and (2) to correlate these hemodynamic changes with the clinical features that subsequently developed. Foot volumetry, a noninvasive, objective, and accurate technique, was used to measure hemodynamic changes. Within 2 years of DVT, there was severe hemodynamic impairment (equivalent to that seen in established postphlebitic limbs) in a fifth of the limbs with calf vein DVT, and in half of the limbs with more extensive proximal DVT. Symptoms were worse after major DVT. Even when successful, thrombolytic therapy does not prevent hemodynamic deterioration. The results appear to be no better than for a group of patients who, with the same degree of thrombosis, received heparin therapy.

Female↗
PubMed1985

Response of rat paraventricular neurones with central projections to suckling, haemorrhage or osmotic stimuli.

In lactating, urethane-anaesthetized female rats extracellular recordings were made from paraventricular nucleus (PVN) neurones that were antidromically activated following electrical stimulation of the neurohypophysis, amygdala or nucleus tractus solitarius/vagal complex (NTS/VC). Of the PVN units, 98 projected to the neurohypophysis but none of these neurosecretory neurones were found to simultaneously project to extrahypothalamic areas. From the firing patterns and the response of these neurons to suckling, haemorrhage or osmotic stimuli both 'vasopressinergic' and 'oxytocinergic' neurones were identified. We found 43 PVN units to project to the NTS/VC and 22% of tested neurones were activated by osmotic or haemorrhage stimuli; no phasic activity was associated with this activation. The suckling stimulus failed to elicit any response from these units. Upon testing the PVN units that projected to the amygdala (n = 35), it was found that haemorrhage and suckling stimuli were without effect, while the osmotic stimulus activated one of 6 units tested. Thus, the extrahypothalamic PVN projections examined in this study were not associated with the suckling reflex response, although there is evidence for their limited involvement in neural response to osmotic or haemorrhage stimuli.

Amygdala↗
PubMed1985

The lack of 'sensitization' to the pressor effects of centrally injected vasopressin in rats.

Vasopressin causes motor disturbances following intracerebroventricular injections and a second central injection results in an apparent sensitization of the animal to the convulsant effect of vasopressin. In this study, the effect of vasopressin pretreatment on the central and peripheral pressor effects of vasopressin was examined in Sprague-Dawley rats. There was no increase in the responsiveness to the pressor effects of vasopressin, either central or peripheral, in animals that had previously received central vasopressin. This evidence suggests that the phenomenon of increased sensitivity to vasopressin is not displayed by all vasopressin's actions.

Animals↗
PubMed1985

Interaction between descending paraventricular neurons and vagal motor neurons.

The hypothalamic paraventricular nucleus is known to send projections to the dorsal medullary area where it appears to innervate the nucleus tractus solitarius and the dorsal motor nucleus of the vagus. Experiments were carried out in urethane anesthetized rats to identify single vagal motor neurons identified by antidromic invasion and to determine their response to stimulation of the paraventricular nucleus (PVN) of the hypothalamus. From the ipsilateral vagus, 26 single units were antidromically activated. Of these, the majority were unresponsive to PVN stimulation; however, 3 of these neurons demonstrated orthodromic excitation following paraventricular stimulation. These studies provide electrophysiological evidence in support of an interaction between descending paraventricular neurons and vagal motor neurons, but indicate that the majority of such vagal neurons are not influenced directly by the PVN.

Animals↗
PubMed1985

Activated protein C stimulates the fibrinolytic activity of cultured endothelial cells and decreases antiactivator activity.

The effects of bovine activated protein C (APC) on the fibrinolytic activity of cultured bovine aortic endothelial cells were investigated. Confluent monolayers were incubated with purified APC under various conditions and changes in total fibrinolytic activity and in the level of plasminogen activator and plasminogen activator inhibitor (antiactivator) were monitored. The addition of APC to the cells in the absence of other blood or plasma components led to a rapid, dose-dependent increase of fibrinolytic activity both in the media and in cellular extracts. For example, 3.4 micrograms of APC per ml resulted in a 15-fold increase of fibrinolytic activity in the medium within 1 hour. The enhanced fibrinolytic activity reflected increases in both the urokinase-related and tissue-type plasminogen activators produced by these cells. Interestingly, treatment of cells with APC also caused a rapid, dose-dependent decrease in antiactivator activity. Diisopropyl fluorophosphate-inactivated APC did not decrease antiactivator or increase plasminogen activator. Although a small but significant direct (i.e., cell-independent) effect of APC on both fibrinolytic activity and antiactivator activity could be demonstrated, the major portion of these changes appeared to be cell-mediated. These observations indicate that the fibrinolytic potential of cultured endothelial cells is increased by APC and that the enzyme active site is essential for this change. Moreover, the results suggest that one of the primary mechanisms for this stimulation of endothelial cell fibrinolytic activity involves an APC-mediated decrease in antiactivator.

Animals↗
PubMed1984

Electrophysiological identification of neurons in the parabrachial nucleus projecting directly to the hypothalamus in the rat.

Experiments were done in urethane anesthetized rats to identify single units in the region of the parabrachial nucleus (PBN) projecting directly to 'cardiovascular' responsive sites in either the paraventricular nucleus of the hypothalamus (PVH) or the supraoptic commissure and nucleus (SOC-SON) region. Fifty-five single units were antidromically activated in the ipsilateral PBN by electrical stimulation of either the PVH (n = 27) or SOC-SON region (n = 28) with latencies corresponding to conduction velocities of 0.3-5.1 m/s. The axons of PBN units projecting to the PVH conducted at significantly slower velocities (0.5 +/- 0.04 m/s) than those projecting to the SOC-SON region (1.6 +/- 0.25 m/s). These data suggest that ascending fibers from the PBN to the PVH are unmyelinated, whereas those to the SOC-SON region are primarily a little myelinated. In addition, since the PBN is known to receive cardiovascular and visceral afferent inputs, it is suggested that these neurons likely function in relaying this afferent information to hypothalamic areas involved in autonomic regulation.

Animals↗
PubMed1984

A direct, plasmin-independent assay for plasminogen activator.

A direct assay for plasminogen activator (PA) was developed. It employed polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and beta-mercaptoethanol to monitor PA-mediated conversion of single chain, 125I-plasminogen to two chain plasmin. By incorporating Triton X-100, albumin and trasylol in the reaction buffer, we were able to minimize the adsorptive and autolytic loss of reactants frequently associated with similar approaches. Under these conditions, plasmin formation was linear for at least 24 hours, dose-dependent over a 20-fold range of urokinase concentrations, and at least 100-fold more sensitive (0.05 units/ml) than previously reported direct assays for PA. The versatility of the assay was demonstrated by its ability to distinguish between urokinase-like and tissue-type PA, and to quantitate the effects of agents like fibrin and epsilon-amino caproic acid on their respective activities. The assay was readily adapted to detect inhibitors of PA in various samples, and was employed to demonstrate the presence of such inhibitors in both rabbit and bovine endothelial cells. Interestingly, the rabbit inhibitor was found to block the activity of urokinase but not that of tissue-type PA, while the bovine inhibitor neutralized the activities of both molecules. These results demonstrate that cleavage of 125I-plasminogen can be employed as a direct, sensitive and quantitative assay for various PAs, and thus offers a new approach for studying plasminogen activation and agents that stimulate or inhibit it.

Aminocaproic Acid↗
PubMed1984

Lateralization of weight in the presence of structural short leg: a preliminary report.

Previous research has reported upon the use of a radiographic method to determine the presence of structural short leg using full spine radiography. In the current study, ninety-two (92) freshman students at the National College of Chiropractic in Lombard, Illinois were first measured for the presence of structural short leg and then placed on a modified Janse-Illi four quadrant weight scale. Measurements of weight were taken at fifteen, thirty, forty-five and sixty seconds. Precise placement of the feet were used. The data collected in kilograms of weight was then converted to total force in Newtons, and the data was normalized as percentage of total body weight. This was then compared to the side of structural short leg. Certain trends have tended to appear. Those subjects with small leg length differential had a greater tendency to bear weight upon the homolateral side of short leg, while those with greater degree of short leg (six millimeters or more) tended to bear weight upon the contralateral leg. It is felt that this is so due to a compensatory mechanism involving the gluteus medius muscle in its use as a "tie-rod" for pelvic function. The greater the degree of short leg, the more the gluteus medius is needed to level the pelvis, and thus the greater shift of body weight to the contralateral side. With a small leg length differential the compensatory mechanism is believed not to be activated, and thus weight bearing will occur on the homolateral side.(ABSTRACT TRUNCATED AT 250 WORDS)

Body Weight↗
PubMed1983

Behavioral, physiological, and neuroendocrine responses to arecoline in normal twins and "well state" bipolar patients.

Cholinergic supersensitivity has been postulated to be an etiologic factor in affective disorder. After several pilot dose-response studies, we administered 8 mg of the cholinergic agonist arecoline subcutaneously to eight pairs of normal volunteer identical twins and eight bipolar patients currently euthymic and unmedicated. During the hour following arecoline administration, the Profile of Mood States (POMS) showed an increase in total mood disturbance in both patient and control groups. Mean systolic blood pressure, pulse, plasma cortisol, prolactin, and growth hormone also increased. Anger and elation scores on the POMS showed significant concordance in identical twins, as did change in prolactin, implying that these are the components of drug response possibly influenced by genetic factors. None of these responses differentiated well state patients from controls. Thus, mood, behavioral, and neurochemical responses to arecoline, which appears to have nonspecific neurochemical effects at the dose employed, are not markers of vulnerability to affective illness.

Arecoline↗