Quantitative radionuclide assessment of total pulmonary vascular volume changes

Current techniques do not permit continuous and noninvasive assessments of changes in total pulmonary intravascular volume. Hence, the present study was undertaken to determine whether quantitative radionuclide imaging can be used to determine the direction and estimate the magnitude of total pulmonary vascular volume changes. The pulmonary circulation was separately perfused at a constant rate via the pulmonary artery and drained at a constant pressure via the left atrium in nine dogs. Changes in pulmonary intravascular volume were recorded as reciprocal changes in extracorporeal reservoir volume during phenylephrine or isoproterenol administration, a 20% increase in pulmonary artery flow or a 5 mmHg (1 mmHg = 133.32 Pa) decrease in left atrial pressure. Erythrocytes were labeled with technetium-99m and pulmonary volume changes were determined from tissue attenuation, blood radioactivity, and changes in total pulmonary radioactivity obtained with a gamma-camera. During each of the interventions, count changes correlated with volume changes (r greater than or equal to 0.75). The technique reliably detected volume changes as small as 10 mL. For all 531 individual pairs of radionuclide- and reservoir-determined volume changes, the correlation between reservoir-determined and radionuclide-estimated pulmonary intravascular volume changes was 0.87. The standard error of the radionuclide estimate was 21 mL. Hence, the present study demonstrates that quantitative radionuclide imaging can be used to continuously and noninvasively determine total pulmonary vascular volume changes.

Alpha-adrenergic regulation of splanchnic volume and cardiac output in the dog

The present study examined whether alpha-adrenergic stimulation causes a change in splanchnic intravascular volume in the anaesthetized animal with an intact circulation, which region(s) mediate the volume change, and whether the splanchnic volume change influences cardiac output. In order to ascertain that a radionuclide imaging technique could be used to assess total splanchnic volume changes, drugs known to increase or decrease splanchnic volume were infused on 21 occasions in eight dogs studied under conditions of selective perfusion and drainage of the splanchnic vasculature with erythrocytes labelled with 99Tcm and a gamma camera placed over the abdomen. For these 21 infusions, volume and radionuclide count changes were related: r greater than or equal to 0.90 (n = 20), r = 0.76 (n = 1). After ascertaining tissue attenuation and blood radioactivity in four of the animals, the standard error for a single estimate of the absolute volume change using the radionuclide technique was determined to be 75 ml. In six animals with intact circulations, phenylephrine (40-80 micrograms min-1) for 20 min was associated with an increase in cardiac output of 12 +/- 2% (P less than 0.001) and a decrease in total splanchnic volume estimated to be 431 +/- 95 ml (P less than 0.001). The splanchnic volume decrease was due entirely to decreases in splenic and intestinal volume. In eight eviscerated animals, cardiac output decreased by 30 +/- 2% (P less than 0.001) during phenylephrine.(ABSTRACT TRUNCATED AT 250 WORDS)

Spatiotemporal segregation of endothelial cell integrin and nonintegrin extracellular matrix-binding proteins during adhesion events

Bovine aortic endothelial cell (BAEC) attachments to laminin, fibronectin, and fibrinogen are inhibited by soluble arginine-glycine-aspartate (RGD)-containing peptides, and YGRGDSP activity is responsive to titration of either soluble peptide or matrix protein. To assess the presence of RGD-dependent receptors, immunoprecipitation and immunoblotting studies were conducted and demonstrated integrin beta 1, beta 3, and associated alpha subunits as well as a beta 1 precursor. Immunofluorescence of BAECs plated on laminin, fibronectin, and fibrinogen reveals different matrix-binding specificities of each of these integrin subclasses. By 1 h after plating, organization of beta 1 integrin into fibrillar streaks is influenced by laminin and fibronectin, whereas beta 3 integrin punctate organization is influenced by fibrinogen and the integrin spatial distribution changes with time in culture. In contrast, the nonintegrin laminin-binding protein LB69 only organizes after cell-substrate contact is well established several hours after plating. Migration of BAECs is also mediated by both integrin and nonintegrin matrix-binding proteins. Specifically, BAEC migration on laminin is remarkably sensitive to RGD peptide inhibition, and, in its presence, beta 1 integrin organization dissipates and reorganizes into perinuclear vesicles. However, RGD peptides do not alter LB69 linear organization during migration. Similarly, agents that block LB69--e.g., antibodies to LB69 as well as YIGSR-NH2 peptide--do not inhibit attachment of nonmotile BAECs to laminin. However, both anti-LB69 and YIGSR-NH2 inhibit late adhesive events such as spreading. Accordingly, we propose that integrin and nonintegrin extracellular matrix-binding protein organizations in BAECs are both temporally and spatially segregated during attachment processes. High affinity nonintegrin interaction with matrix may create necessary stable contacts for longterm attachment, while lower affinity integrins may be important for initial cell adhesion as well as for transient contacts of motile BAECs.

Influence of splanchnic intravascular volume changes on cardiac output during muscarinic receptor stimulation in the anaesthetized dog

The direct influence of systemic muscarinic receptor stimulation on total splanchnic intravascular volume and the splanchnic organs responsible for the total splanchnic volume change associated with muscarinic receptor stimulation in the animal with an intact circulation are unknown. Furthermore, the subsequent effect of these volume changes on cardiac output is not known. Thus, acetylcholine was infused at 5 micrograms kg-1 min-1 in 25 anaesthetized dogs in which nicotinic blockade of the ganglia was achieved with mecamylamine, while total and regional splanchnic intravascular volume changes were determined with a radionuclide imaging technique. Total splanchnic volume decreased by 4.9 +/- 1.0% (P less than 0.0001), splenic volume decreased by 10.3 +/- 2.0% (P less than 0.0001), hepatic volume increased by 5.8 +/- 1.4% (P less than 0.01), extrahepatosplenic volume increased by 6.6 +/- 1.6% (P less than 0.01) and cardiac output increased from 1960 +/- 190 to 2290 +/- 230 ml min-1 (P less than 0.001). After splenectomy (n = 13), the hepatic and extrahepatosplenic volume increments were abolished, and the increase in cardiac output was not attenuated (1600 +/- 260 to 2040 +/- 370 ml min-1). After subsequent evisceration (n = 5), the cardiac output increment associated with acetylcholine was still not attenuated. Acetylcholine-associated splanchnic volume changes were abolished after muscarinic receptor blockade with atropine. Thus, muscarinic receptor stimulation causes a decrease in total splanchnic volume due entirely to a decrease in splenic volume. The splanchnic volume changes do not influence cardiac output.

Effect of platelet factors on migration of cultured bovine aortic endothelial and smooth muscle cells

Endothelial cell (EC) injury and the response of EC and smooth muscle cells (SMCs) to injury contribute to the pathophysiology in patients with vascular disease and atherosclerosis. Since platelets have been suggested to play an important role in modulating vascular injury, the present study was undertaken to examine the influence and mechanism of action of individual platelet factors on bovine aortic EC and SMC migration using an in vitro wound assay system. Serotonin decreased EC proliferation and reduced EC migration 21 +/- 1% (p less than 0.005), which was attenuated by imipramine. Transforming growth factor-beta reduced EC proliferation and decreased EC migration 52 +/- 3% (p less than 0.005). Norepinephrine increased EC proliferation but decreased EC migration 26 +/- 2% (p less than 0.005), which was abolished by phenoxybenzamine. Histamine increased EC proliferation but reduced EC migration 29 +/- 2% (p less than 0.005), which was attenuated by diphenhydramine. Platelet-derived growth factor decreased EC proliferation and decreased EC migration 40 +/- 2% (p less than 0.005). In contrast, serotonin increased SMC proliferation and increased SMC migration 31 +/- 2% (p less than 0.005), which was abolished by ketanserin. Transforming growth factor-beta increased SMC migration 35 +/- 5% (p less than 0.005). Norepinephrine increased SMC proliferation and increased SMC migration 43 +/- 4% (p less than 0.005), which was abolished by propranolol. Histamine increased SMC proliferation and increased SMC migration 38 +/- 3% (p less than 0.005), which was abolished by cimetidine. Platelet-derived growth factor increased SMC proliferation and increased SMC migration 40 +/- 3% (p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of verapamil on total and regional intravascular volume in dogs

Verapamil's influence on intravascular volume (IV) in the total capacitance circulation was examined in anesthetized dogs after mecamylamine or baroreceptor denervation. Blood was drained from the venae cavae to an extracorporeal reservoir and returned to the right atrium at a constant rate so that IV changes could be measured as reciprocal changes in reservoir volume. In 10 dogs, verapamil (50 micrograms/min) caused a decrease in total IV of 74 +/- 12 ml (P less than 0.0005) at 20 min and a decrease in arterial pressure from 79 +/- 5 to 66 +/- 3 mmHg (P less than 0.0005). After evisceration in nine animals, verapamil caused an extrasplanchnic (XSPL) IV decrease of 97 +/- 19 ml (P = 0.08). In 11 animals with separate perfusion and drainage of the splanchnic and XSPL circulations, verapamil caused an XSPL IV decrease of 74 +/- 20 ml (P less than 0.002) and a splanchnic IV increase of 19 +/- 9 ml (P = 0.06). In four animals on cardiopulmonary bypass, IV decreased 154 +/- 66 ml (P less than 0.002) during verapamil administration. Thus total IV decreases due to a decrease in systemic extrasplanchnic volume. Because pressure decreased while arterial flow and venous outflow pressure were constant, a decrease in the resistance to blood return to the central circulation mediates the XSPL volume decrement.

Endothelial cell behavior after denudation injury is modulated by transforming growth factor-beta1 and fibronectin

Endothelial denudation injury after endarterectomy, autologous and synthetic grafting and balloon angioplasty leads to exposure of thrombogenic vessel wall material and may elicit an atherogenic response in the media of the affected vessels in which complete reendothelialization may not occur. While the role(s) of extracellular matrix composition and organization in this process are only incompletely understood, it is widely accepted that endothelial cells respond to matrix components in specific, complex fashions. In this report we demonstrate that large vessel endothelial cell migration is affected by the surrounding matrix and the soluble factor, transforming growth factor-beta1, which may mediate its effects, in part, by modulating endothelial cell matrix synthesis. Specifically, large vessel endothelial cell migration is decreased on a fibronectin substratum and in the presence of transforming growth factor-beta1, which increases fibronectin mRNA and protein accumulation in culture. Inhibition of sheet migration is also elicited by the addition of soluble fibronectin to the cultures. These in vitro findings are consistent with our in vivo findings of increased staining of fibronectin luminally and in the intima in the chronically deendothelialized region of a balloon catheter denuded carotid artery. Thus, reendothelialization after iatrogenic and natural injury appears to be a complex process which can be modulated by the underlying matrix and soluble factors, which may themselves modulate the matrix synthesis of local vascular cells.

The STE4 and STE18 genes of yeast encode potential beta and gamma subunits of the mating factor receptor-coupled G protein

The STE4 and STE18 genes are required for haploid yeast cell mating. Sequencing of the cloned genes revealed that the STE4 polypeptide shows extensive homology to the beta subunits of mammalian G proteins, while the STE18 polypeptide shows weak similarity to the gamma subunit of transducin. Null mutations in either gene can suppress the haploid-specific cell-cycle arrest caused by mutations in the SCG1 gene (previously shown to encode a protein with similarity to the alpha subunit of G proteins). We propose that the products of the STE4 and STE18 genes comprise the beta and gamma subunits of a G protein complex coupled to the mating pheromone receptors. The genetic data suggest pheromone-receptor binding leads to the dissociation of the alpha subunit from beta gamma (as shown for mammalian G proteins), and the free beta gamma element initiates the pheromone response.

Syphilis detection in cerebrovascular disease

To determine the importance of syphilis testing in cerebrovascular disease, we prospectively assessed 218 consecutive patients with either transient ischemic attack or completed stroke. The results from this study group were compared with those from a control group of 150 neurological patients without cerebrovascular disease. Of 275 patients from both groups specifically tested by the fluorescent treponemal antibody-absorption test, 34% of the study group were seropositive compared with 18% of the controls (chi 2 = 7.7, p less than 0.01). Fifty-four percent of the patients with a positive fluorescent treponemal antibody-absorption test underwent a cerebrospinal fluid examination; meningovascular syphilis was detected in one (0.4%) of these. This patient was a homosexual male with antibodies to the human immunodeficiency virus; a second patient, with possible meningovascular syphilis, also had antibodies to this virus. Despite the relatively high rate of syphilis seropositivity noted in our study group, syphilis was not found to be a common cause of cerebrovascular disease; therefore, routine screening is seen to be of low diagnostic yield. Attention to patients who are at higher risk for syphilitic infection, patients with clinical features suggestive of meningovascular syphilis, and the proper choice of serologic studies can help make the assessment of syphilis seropositivity more clinically appropriate and cost effective.

Timing of ovulation for artificial insemination

Two studies involving eighty women having treatment with artificial insemination by donor (AID) have demonstrated that the use of a urinary semi-quantitative assay for luteinising hormone (LH) gives pregnancy rates comparable to those obtained using plasma LH for the timing of insemination. The advantage of self test assay is evident in a scattered region such as Grampian.

Muscarinic regulation of pulmonary intravascular volume in isolated canine lungs

The influence of acetylcholine on pulmonary intravascular volume has not been clearly identified. In 14 anesthetized dogs, the pulmonary circulation was separately perfused in situ at a constant rate and drained to an extracorporeal reservoir, so that changes in total pulmonary intravascular volume could be recorded as reciprocal changes in reservoir volume. In eight animals, acetylcholine at 100 micrograms/min for 20 min was associated with increases in pulmonary intravascular volume (PIV) and pulmonary arterial pressure of 41 +/- 5 (SE) ml (P less than 0.001) and 2.0 +/- 0.0 mmHg (P less than 0.001; 11 infusions), respectively. These responses were abolished after atropine (6 infusions). In six animals, pulmonary venous pressure was also measured, so that total pulmonary (TPR), pulmonary arterial (PAR), and pulmonary venous (PVR) resistances could be calculated. TPR and PVR increased from 21 +/- 2 to 24 +/- 3 (P less than 0.001) and from 7 +/- 1 to 11 +/- 1 mmHg.min.l-1 (P less than 0.001), respectively, while PAR did not change significantly (6 infusions). In three of the six animals, these changes were abolished by atropine (6 infusions). In the other three animals, PIV increased 56 +/- 11 ml (P less than 0.001) before and 47 +/- 6 ml (P less than 0.001) after indomethacin. The acetylcholine-associated increases in TPR and PVR were also not significantly attenuated after indomethacin. Hence, muscarinic receptor stimulation with acetylcholine is associated with an increase in pulmonary intravascular volume, which is mediated by an increase in resistance to pulmonary venous outflow. These changes are not due to release of prostanoids.(ABSTRACT TRUNCATED AT 250 WORDS)

The dissatisfied medical patient: predictors of intent to change doctors

A favorable patient-doctor relationship is critical for the maintenance of a stable and productive practice. Most adults are likely to have had experiences in physician's offices that have caused upset or dissatisfaction. Many of these experiences will have resulted in changing doctors. The likelihood of changing doctors is more often related to the physician's behavior than to his or her actual competence or efficacy.

Fetal growth and fetal lung phospholipid content in rats fed safflower oil, menhaden oil, or hydrogenated coconut oil

The objective was to determine if dietary fish oil decreased the degree of fatty acid saturation in rat lung phosphatidylcholine (PC). A diet containing 12% of its energy as fat was fed for 3 wk to growing male Sprague-Dawley rats (trial I) or to pregnant rats for days 8-21 of gestation (trial II). The dietary fat treatments in trial I were safflower oil (SO), menhaden oil (MO), or hydrogenated coconut oil (HCO) and in trial II were SO, MO, HCO, or SO-MO (75%:25%). Polyunsaturated fatty acids reduced (p less than 0.05) hepatic fatty acid synthetase (MO greater than SO) in growing rats but the dietary lipids had no effect on lung palmitate content. Maternal consumption of MO vs SO reduced (p less than 0.05) fetal body weight and lung weight but not lung:body wt ratio. Dietary MO and SO-MO increased (p less than 0.05) disaturated PC content of fetal lungs. The fetal lung data indicate that maternal ingestion of fish oil improve fetal lung maturation.

The presence and significance of intraepithelial mesenchymal cells in human foetal colon

During an investigation of the morphogenesis of the human foetal colon, breaks in the basal lamina underlying the surface epithelium were frequently observed at 10 1/2-11 weeks. These occurred at those sites where the mesenchyme was sweeping up into the epithelium prior to the transformation of the epithelium from stratified to a single layer. At the same time numbers of mesenchymal cells appeared among the epithelial cells and some were observed actually in the process of passing through the gaps in the basal lamina. Close contact was apparent between some mesenchymal cells and basal epithelial cells through extended breaks in the basal lamina. Many of the mesenchymal cells within the epithelium contained numbers of apoptotic bodies. This suggests that one of the functions of the intra-epithelial mesenchymal cells is to remove the debris resulting from cell death which occurs in association with the re-arrangement of cells during development of the colon.

Evaluation of kinetic therapy in the prevention of complications of prolonged bed rest secondary to stroke

We performed a prospective, controlled study of kinetic therapy in acute, severe stroke. This therapy involved continuous mobilization of a bedridden patient by means of a specially designed rotating bed. All patients with acute stroke presenting to the Neurology Service over an 18-month period were screened, and those that qualified were assigned to confinement in either a routine hospital bed or a rotating bed. We found that the most common complication of stroke with bed confinement of 4 days or longer was bacterial infection consisting of either pneumonia, sepsis, or urinary tract infection. The two variables found to be of greatest significance in affecting the rate of infection were length of bed confinement, especially for greater than 13 days (2.3-fold increased risk, p less than 0.04), and placement in a routine hospital bed (2.9-fold increased risk, p = 0.023).

Trisomy 1 in an eight cell human pre-embryo

The high incidence of chromosome abnormalities in clinically recognised pregnancies is well documented, but experience of these problems at the time of conception is extremely limited. Using donated oocytes from women seeking surgical sterilisation, we have established reliable cytogenetic techniques for chromosome analysis of human pre-embryos. These have resulted in the first report of trisomy 1. The pre-embryo showed no other obvious abnormality in relation to follicular characteristics, embryo morphology, and cleavage kinetics. The usefulness of such data in explaining the high incidence of occult human pregnancy loss and the current poor success following embryo replacement is emphasised.

A new mutation at the cmd locus in the mouse

A short limb dwarfing syndrome that arose in BALB/cGaBc inbred mice appeared to segregate as a Mendelian autosomal recessive lethal mutation. Anatomical and histological studies of newborns showed shortening and widening of most cartilaginous bones, shortening of the head, subcutaneous edema, and engorgement of liver with blood. Cartilage showed deficiency of acid mucopolysaccharide in the extracellular matrix and strain excessively for collagen. The primary cause of death at birth is probably the extremely compressed anterior thorax. The new mutation behaves as an allele of cartilage matrix deficiency (cmd) and is provisionally named cmdBc.

The role of the splanchnic circulation in the regulation of total intravascular volume during alpha adrenergic receptor stimulation

Previous studies have not defined the contribution of the splanchnic circulation to the total intravascular volume change associated with selective alpha adrenergic receptor stimulation. Since the splanchnic circulation is responsible for the total volume changes associated with other types of selective autonomic receptor stimulation, the present study was undertaken to examine the influence of alpha adrenergic receptor stimulation on splanchnic intravascular volume, the hemodynamic mechanism responsible for the splanchnic volume change, and the contribution of the splanchnic volume change to the change in total volume. In 35 anesthetized dogs, blood from the vena cavae was drained into an extracorporeal reservoir and returned to the right atrium at a constant rate so that changes in total intravascular volume could be measured as reciprocal changes in reservoir volume. Phenylephrine infusion (100 micrograms/min) for 20 min in 28 dogs was associated with a decrease in total volume of 64 +/- 17 (SEM) ml (P less than 0.0001). The response was abolished by either alpha adrenergic blockade or evisceration but was not attenuated by beta adrenergic blockade, sinoaortic baroreceptor denervation, ganglionic blockade, or splenectomy. In 5 animals with separate splanchnic perfusion and drainage, total and splanchnic volumes decreased 59 +/- 8 ml (P less than 0.0001) and 317 +/- 20 ml (P less than 0.0001), respectively, while transhepatic vascular resistance increased 17 +/- 4 cm H2O X min/l (P less than 0.0001). These responses were abolished after alpha adrenergic blockade. Thus, splanchnic volume decreases with alpha adrenergic receptor stimulation, despite an increase in hepatic resistance to splanchnic venous outflow. The splanchnic volume decrement is entirely responsible for the total volume decrement.

Model for determination of 13C substrate oxidation rates in humans in the fed state

The effect of a test diet of conventional North American foods on breath 13CO2 abundance was determined in 4 healthy males. Subjects consumed a diet containing 41.9% energy as fat and a polyunsaturated:saturated fatty acid ratio of 0.217 for 5 days at a level equal to estimated requirements for total energy. One subject underwent four 5-day feeding periods. Over the feeding period mean change in subjects' body weight was -0.165 +/- 0.64% (means +/- SEM) of initial body weight. On day 5 breath samples were collected hourly from 0745 to 1645 h and analyzed for 13CO2 enrichment relative to the pre-breakfast fasted state (level at 0745 h). Breakfast and lunch were consumed at 0820 and 1300 h respectively. Mean enrichment peaked at 1445 h at 0.00311 atom % excess above fasting level for all subjects and 0.00243 atom % excess for the four repeated trials on one subject. Between subject variation (SEM) in 13CO2 enrichment (0.000618 atom %) was significantly greater than within subject variation (0.000308 atom %). These results indicate that ingestion of normal meals during the breath test period increases breath 13CO2 abundance due to a shift in substrate oxidation. The small within subject variation in repeated 13CO2 enrichment profiles indicates the reliability of 13C breath tests using controlled diets. It is concluded that for tests conducted under identical conditions, an initial background 13CO2 abundance profile determined once for each subject, can be subtracted from the subsequent enrichment profile generated by a labeled test substrate.