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Biomedical subjects

R L Jones

Publications and source records attributed to R L Jones.

At least 271 records · Page 15Linked to original sources
PubMed1985

Ventilation by external high-frequency oscillation in cats.

Eight anesthetized tracheostomized cats were placed in an 8.2-liter airtight chamber with the trachea connected to the exterior. Thirty-two combinations of high-frequency oscillations (HFO) (0.5-30 Hz; 25-100 ml) were delivered for 10 min each in random order into the chamber. Arterial blood gas tensions during oscillation were compared with control measurements made after 10 min of spontaneous breathing without oscillation when the mean arterial PCO2 (PaCO2) was 30.1 Torr. Ventilation due to spontaneous breathing (Vs) and oscillation (Vo) were derived from the chamber pressure trace and a pneumotachograph, respectively. As the oscillation frequency increased, oscillated tidal volume (Vo) decreased from a mean of 39 (0.5 Hz) to 3.3 ml (30 Hz) when 100 ml was delivered to the chamber. From 6-25 Hz, apnea occurred with Vo less than estimated respiratory dead space (VD); the minimum effective Vo/VD ratio was 0.37 +/- 0.05. Although Vo was maximal at 10 Hz at each oscillation volume, the lowest PaCO2 occurred at 2-6 Hz, and arterial PO2 rose as expected during hypocapnia. Above 10 Hz, PaCO2 was determined by Vo and was independent of frequency, whereas at lower frequencies, PaCO2 was related to Vo; below 6 Hz, PaCO2 varied inversely with the calculated alveolar ventilation. As oscillations became more effective, both PaCO2 and Vs fell progressively and were highly correlated; apnea occurred when PaCO2 was reduced by a mean of 4.5 Torr. Mean chamber pressure remained near zero up to 15 Hz, indicating functional residual capacity did not change. We conclude that externally applied HFO can readily maintain gas exchange in vivo, with Vo less than VD at frequencies over 2 Hz.

Animals↗
PubMed1985

Comparison of plethysmographic methods for obtaining thoracic gas volume in anesthetized dogs.

Thoracic gas volume (TGV) cannot be measured in the body plethysmograph by the standard spontaneous breathing technique (SB) when there is a significant respiratory center depression. In this case, either external compression of the chest wall (EC) or phrenic nerve stimulation (PhN) can be used to induce the pressure-volume changes necessary to calculate TGV. In the present study we compared TGV measured in eight pentobarbital-anesthetized dogs by SB, EC, PhN, and the standard He-dilution method. EC and simulated PhN were also used to measure the volume of a lung model, and EC was used to measure the volume of isolated lung lobes. A method for fast and accurate plethysmographic calibration is also described. In the intact dogs, SB, PhN, and He-dilution techniques gave similar results, but EC overestimated TGV. In the isolated lobes and lung model EC accurately measured volume. We speculate that EC induces substantial intersegmental and/or interlobal gas movement in intact lungs and that the pressure drop due to airway resistance causes proximal airway pressure to underestimate alveolar pressure changes, which induces overestimation in calculated TGV. We conclude that PhN is the method of choice to measure plethysmographic TGV when the respiratory center is depressed and that EC overestimates TGV in intact dogs.

Animals↗
PubMed1985

The effect of methacholine inhalation challenge on regional residual volume in patients with subclinical asthma.

Regional residual volume to total lung capacity (RVr/TLCr) was measured with xenon 133 before and after methacholine challenge in 26 nonsmoking subjects (mean age 34 years). Eleven were normal control subjects and 15 were patients referred for methacholine challenge because of previous asthma-like symptoms. All had normal pulmonary function and normal RVr/TLCr distribution. Following methacholine challenge, RVr/TLCr increased in two control subjects and ten patients who also had decreases in FEV1 of greater than 20 percent. The RVr/TLCr changes were patchy, suggesting that the degree of bronchospasm varied between individual lung regions. The other 14 subjects did not have a 20 percent decrease in FEV1, but two controls and four patients had generalized increases in RVr/TLCr, while seven controls and one patient had no significant changes in RVr/TLCr. In all subjects, FEV1 and RVr/TLCr returned to the baseline level after salbutamol administration. The results indicate that methacholine can cause localized or diffuse effects on lung emptying and that bronchodilator completely reverses the bronchoconstriction induced by methacholine.

Adult↗
PubMed1985

Fibrinopeptide-A in diabetes mellitus. Relation to levels of blood glucose, fibrinogen disappearance, and hemodynamic changes.

Plasma and urine fibrinopeptide-A (FPA) levels were investigated in type I and II diabetic patients. Plasma FPA and 24-h urinary excretion of FPA were significantly elevated in diabetic patients compared with normal volunteers, indicating augmented thrombin activity in diabetes. Plasma and urine FPA did not differ between type I and type II diabetic subjects. Comparison of plasma FPA with blood glucose and hemoglobin A1 (HbA1) indicated that elevation of FPA is rapidly reversible and intermittent during hypo- and hyperglycemia. Although elevated plasma FPA was seen in patients of short as well as long duration of diabetes, plasma and urine FPA correlated with duration of diabetes in type I patients. In type I diabetic patients with vascular complications, hyperglycemia induced by an oral glucose challenge was accompanied by elevation of plasma FPA and acceleration of fibrinogen disappearance. These responses were not seen when the patients were treated with intravenous (i.v.) heparin before the glucose challenge. In patients without vascular complications, there was also an acceleration of fibrinogen disappearance and a marginal (not statistically significant) elevation of plasma FPA seen after the FPA response observed in vascular disease patients. In all patients, induced hyperglycemia resulted in a decrease in hematocrit and hemoglobin (blood volume expansion) and an increase in pulse pressure indicating hemodynamic changes. The association of hyperglycemia and hemodynamic changes with augmented thrombin activity is consistent with a mechanism for fibrin formation and deposition based on endothelial injury and/or increased vascular permeability. Fibrin deposition due to such a mechanism may participate in the development of the vascular complications of diabetes.

Adolescent↗
PubMed1985

Thermoregulation during aerobic exercise in pregnancy.

To characterize maternal thermal balance during pregnancy, the authors recorded the thermal response to moderate weight bearing exercise stress in four aerobically conditioned pregnant women. Studies were performed in a climate-controlled environment in each trimester of pregnancy and postpartum after modifying the exercise protocol for changes in maternal exercise condition. Core, vaginal, and mean skin temperatures were recorded at rest and during maximum exercise. Mean resting skin temperature increased during pregnancy; mean resting core and vaginal temperatures did not change. Core temperatures did not exceed 39C during exercise. Heat storage (heat content/kg) was not increased as a result of exercise with advancing pregnancy. According to these findings, thermal balance can be maintained with advancing gestation when exercise prescriptions are appropriately modified for conditioned women.

Body Temperature Regulation↗
PubMed1985

Attentional influences on noxious and innocuous cutaneous heat detection in humans and monkeys.

This study examines whether selective attention can influence sensory-discriminative aspects of nociception in humans and monkeys trained to detect innocuous and noxious thermal stimuli. Human subjects had two contact thermodes positioned bilaterally above the upper lip. Upon trial initiation both thermodes heated to either 39 degrees C, an innocuous warm temperature, or 45 degrees C, a slightly noxious temperature. After 4 to 9 sec, the temperature of one thermode increased an additional step of less than 1 degree C. Subjects released a button when they detected this second temperature increase (T2). Three types of trials were presented in order to assess the effects of spatially selective attention on thermal detection. On 40% of the trials a light correctly signaled the location of the thermode on which T2 would occur. On 10% of trials a light incorrectly signaled the location of T2. No signal was presented on the remaining trials. From the 45 degrees C base line, detection latencies were shortest in the correct signal condition, longest in the incorrect signal condition, and intermediate in the unsignaled condition. The percent of undetected T2s was greatest in the incorrect signal condition and least in the correct signal condition. From the 39 degree C base line, the detection latency in the incorrect signal condition was greater than in the unsignaled condition, but the latter latency was not different from the correct signal latency. In addition, the percent of undetected T2s was the same on all three types of trials.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

High-performance liquid chromatography of microbial acid metabolites.

The use of high-performance liquid chromatography with a cation-exchange column and effluent monitoring at 210 nm has been evaluated for the profiling of selected microbial metabolites including aliphatic, dicarboxylic, and phenolic acids, as an adjunct to the identification of selected bacteria, detection of bacterial metabolites in foods, and the monitoring of industrial microbial fermentations. Advantages of the technique include the simultaneous profiling of different classes of organic acids without derivatization. Most applications require only qualitative or semi-quantitative data. For others, data are given on the day-to-day reproducibility for several acids.

Bacteria↗
PubMed1984

Stopped-flow kinetic, 1H, and 31P NMR analysis of the intercalation of ethidium with poly d(G-C) X d(G-C).

In a low salt buffer (0.011 M Na+) stopped-flow kinetic results for the SDS driven dissociation of an ethidium-Poly d(G-C) X d(G-C) complex are 8.7, 23, and 58.5 s-1 at 20, 30, and 40 degrees C, respectively. These results predict that in NMR experiments at high field strengths, ethidium should be in slow exchange among polymer binding sites. This has been found to be the case for both 31P (109 MHz) and 1H (imino proton spectra in H2O at 270 MHz) experiments. At higher salt, and/or higher temperature, and/or lower field, the bound and free peaks are no longer resolved in the NMR spectra. Good agreement is obtained between the stopped-flow kinetic results and the coalescence temperature observed in NMR experiments. Imino protons in base pairs on both sides of the intercalated ethidium are shifted approximately one ppm upfield while only the phosphate groups at the intercalation site experience large chemical shifts.

Chemical Phenomena↗
PubMed1984

Thromboxane-induced phosphatidate formation in human platelets. Relationship to receptor occupancy and to changes in cytosolic free calcium.

The inter-relationships between receptor occupancy, inositol phospholipid metabolism and elevation of cytosolic free Ca2+ in thromboxane A2-induced human platelet activation were investigated by using the stable thromboxane A2 mimetic, 9,11-epoxymethanoprostaglandin H2, and the thromboxane A2 receptor antagonist, EPO45. 9,11-Epoxymethanoprostaglandin H2 stimulated platelet phosphatidylinositol metabolism as indicated by the rapid accumulation of [32P]phosphatidate and later accumulation of [32P]phosphatidylinositol in platelets pre-labelled with [32P]Pi. These effects of 9,11-epoxymethanoprostaglandin H2 were concentration-dependent and half-maximal [32P]phosphatidate formation occurred at an agonist concentration of 54 +/- 8 nM. With platelets labelled with the fluorescent Ca2+ indicator quin 2, resting cytosolic free Ca2+ was 86 +/- 12 nM. 9,11-Epoxymethanoprostaglandin H2 induced a rapid, concentration-dependent elevation of cytosolic free Ca2+ to a maximum of 300-700 nM. Half-maximal stimulation was observed at an agonist concentration of 80 +/- 23 nM. The thromboxane A2 receptor antagonist EPO45 selectively inhibited 9,11-epoxymethanoprostaglandin H2-induced [32P]phosphatidate formation and elevation of cytosolic free Ca2+, indicating that both events are sequelae of receptor occupancy. Human platelets contain a single class of stereospecific, saturable, high affinity (KD = 70 +/- 13 nM) binding sites for 9,11-epoxymethano[3H]prostaglandin H2. The concentration-response curve for receptor occupancy (9,11-epoxymethano-[3H]prostaglandin H2 binding) is similar to that for 9,11-epoxymethanoprostaglandin H2-induced [32P]phosphatidate formation and for elevation of cytosolic free Ca2+. These observations indicate that human platelet thromboxane A2 receptor occupation is closely linked to inositol phospholipid metabolism and to elevation of cytosolic free Ca2+. Both such events may be necessary for thromboxane A2-induced human platelet activation.

Blood Platelets↗
PubMed1984

Georgetown Adolescent Psychosocial Rating Scale.

UNLABELLED: The Georgetown Adolescent Psychosocial Rating Scale (GAPRS) was developed as a clinical tool to be used in the evaluation of the psychosocial development of the adolescent. Preliminary findings have shown it to be useful in assessing normal psychosocial development and identifying deviant states. The GAPRS was developed in a clinical setting over a 5-year period as a questionnaire with the statistical ability to assess adolescent psychosocial development. The data from this study support the GAPRS as a promising new clinical tool to be used with the adolescent patient for assessing normal and deviant psychosocial maturation in an efficient and concise manner. SPECULATION: Adolescent psychosocial maturation can be measured using key questions to measure normal development and deviant states.

Adolescent↗
PubMed1984

Regulation of the synthesis of barley aleurone alpha-amylase by gibberellic Acid and calcium ions.

The effects of gibberellic acid (GA(3)) and calcium ions on the production of alpha-amylase and acid phosphatase by isolated aleurone layers of barley (Hordeum vulgare L. cv Himalaya) were studied. Aleurone layers not previously exposed to GA(3) or Ca(2+) show qualitative and quantitative changes in hydrolase production following incubation in either GA(3) or Ca(2+) or both. Incubation in H(2)O or Ca(2+) results in the production of low levels of alpha-amylase or acid phosphatase. The addition of GA(3) to the incubation medium causes a 10- to 20-fold increase in the amounts of these enzymes released from the tissue, and addition of Ca(2+) at 10 millimolar causes a further 8- to 9-fold increase in alpha-amylase release and a 75% increase in phosphatase release. Production of alpha-amylase isoenzymes is also modified by the levels of GA(3) and Ca(2+) in the incubation medium. alpha-Amylase 2 is produced under all conditions of incubation, while alpha-amylase 1 appears only when layers are incubated in GA(3) or GA(3) plus Ca(2+). The synthesis of alpha-amylases 3 and 4 requires the presence of both GA(3) and Ca(2+) in the incubation medium. Laurell rocket immuno-electrophoresis shows that two distinct groups of alpha-amylase antigens are present in incubation media of aleurone layers incubated with both GA(3) and Ca(2+), while only one group of antigens is found in media of layers incubated in GA(3) alone. Strontium ions can be substituted for Ca(2+) in increasing hydrolase production, although higher concentrations of Sr(2+) are required for maximal response. We conclude that GA(3) is required for the production of alpha-amylase 1 and that both GA(3) and either Ca(2+) or Sr(2+) are required for the production of isoenzymes 3 and 4 of barley aleurone alpha-amylase.

Journal Article↗
PubMed1984

Complications of intravenous DSA performed for carotid artery disease: a prospective study.

One hundred and two patients, who were being evaluated for carotid artery disease, were prospectively studied for complications occurring as a result of intravenous digital subtraction angiography (DSA). We recorded the type, number, and outcome of complications and reviewed the amount of contrast material used, along with the patient's age and medical history for possible correlation with increased complications. There were 55 total complications or side effects involving 37 patients. Central nervous system (CNS) complications included six major-transient and one major-permanent complication. Systemic complications included 20 major-transient and two major-permanent events. The patient's age and the amount of contrast material used did not appear to be significant risk factors. Complications in our series were significantly higher than previous DSA reports and published data on conventional angiography studies. Many of our patients were in a relatively high risk group, including 74 patients who had multisystem disease and 30 who had histories of angina.

Aged↗
PubMed1984

Alterations in pulmonary mechanics and gas exchange during routine fiberoptic bronchoscopy.

Pulmonary function and arterial blood gases were measured in 35 patients undergoing routine diagnostic flexible fiberoptic bronchoscopy (FFB) either through an 8-mm endotracheal tube (ETT) or transnasally in order to investigate whether FFB changes lung function in a way which may explain why hypoxemia commonly occurs during this procedure. In these patients with moderate airway obstruction, functional residual capacity (FRC) increased significantly after inserting the ETT, after placing the FFB in the airway through the ETT, and after inserting the flexible bronchoscope transnasally. The mean increase in FRC was 30 percent in the intubated group before FFB insertion and 17 percent in the transnasal group. Removal of the FFB and ETT caused FRC to return toward the control value. Insertion of the ETT-FFB combination or transnasal FFB did not change PaO2 substantially, although following the examination, PaO2 was decreased significantly in the transnasal group but not in the intubated group. The PaO2 decreased significantly in both groups following removal of the ETT and transnasal FFB. These results suggest that placement of an FFB or ETT-FFB combination in the airway in spontaneously breathing subjects elevates FRC.

Adult↗
PubMed1984

A randomized comparative crossover evaluation of glucose monitoring technologies.

Twenty-four diabetic patients receiving insulin were randomized to 3 groups. Group I began self blood glucose monitoring by meter and switched to visually read strips at 3 months. Group II began self blood glucose monitoring by visually read strips and switched to meter readings at 3 months. Group III monitored urine glucoses for the 6 months of the trial. Professional interaction time was the same for all patients and each patient was placed on the same insulin delivery scheme (3 shots NPH and/or regular). Mean C-peptide levels 6 min following intravenous glucagon was comparable in all 3 groups. Patients monitoring blood glucose showed a significant decrease in glycosylated hemoglobin values (p less than 0.01) from patients monitoring urine at 6 months of the trial. Patients subjectively felt meters were more accurate than visual strips but both groups I and II showed lower glycosylated hemoglobin levels (p less than 0.02 at 6 months) and sequence analysis revealed no sequence effect. The trial confirms that blood glucose monitoring technologies have advantages over urine monitoring in helping patients achieve improved glucose levels. Patients perform equally well in terms of blood glucose "control" whether visually read strips or meters are used for initial teaching or maintenance if patients are instructed appropriately in each methodology. These findings have economic implications for large scale treatment programs.

Adolescent↗