Voyager 2 radio science observations of the uranian system: atmosphere, rings, and satellites

Voyager 2 radio occultation measurements of the Uranian atmosphere were obtained between 2 and 7 degrees south latitude. Initial atmospheric temperature profiles extend from pressures of 10 to 900 millibars over a height range of about 100 kilometers. Comparison of radio and infrared results yields mole fractions near the tropopause of 0.85 and 0.15 +/- 0.05 for molecular hydrogen and helium, respectively, if no other components are present; for this composition the tropopause is at about 52 kelvins and 110 millibars. Distinctive features in the signal intensity measurements for pressures above 900 millibars strongly favor model atmospheres that include a cloud deck of methane ice. Modeling of the intensity measurements for the cloud region and below indicates that the cloud base is near 1,300 millibars and 81 kelvins and yields an initial methane mole fraction of about 0.02 for the deep atmosphere. Scintillations in signal intensity indicate small-scale stucture throughout the stratosphere and upper troposphere. As judged from data obtained during occultation ingress, the ionosphere consists of a multilayer structure that includes two distinct layers at 2,000 and 3,500 kilometers above the 100-millibar level and an extended topside that may reach altitudes of 10,000 kilometers or more. Occultation measurements of the nine previously known rings at wavelengths of 3.6 and 13 centimeters show characteristic values of optical depth between about 0.8 and 8; the maxim value occurs in the outer region of the in ring, near its periapsis. Forward-scattered signals from this ring have properties that differ from those of any of Saturn's rings, and they are inconsistent with a discrete scattering object or local (three-dimensional) assemblies of orbiting objects. These signals suggest a new kdnd of planetary ring feature characterized by highly ordered cylindrical substructures of radial scale on the order of meters and azimuthal scale of kilometers or more. From radio data alone the mass of the Uranian system is GM(sys) = 5,794,547- 60 cubic kilometers per square second; from a combination of radio and optical navigation data the mass of Uranus alone is GM(u) = 5,793,939+/- 60 cubic kilometers per square second. From all available Voyager data, induding imaging radii, the mean uncompressed density of the five major satellites is 1.40+/- 0.07 grams per cubic centimeter; this value is consistent with a solar mix of material and apparently rules out a cometary origin of the satellites.

A cellular lineage analysis of the chick limb bud

The chick limb bud has been used as a model system for studying pattern formation and tissue development for more than 50 years. However, the lineal relationships among the different cell types and the migrational boundaries of individual cells within the limb mesenchyme have not been explored. We have used a retroviral lineage analysis system to track the fate of single limb bud mesenchymal cells at different times in early limb development. We find that progenitor cells labeled at stage 19-22 can give rise to multiple cell types including clones containing cells of all five of the major lateral plate mesoderm-derived tissues (cartilage, perichondrium, tendon, muscle connective tissue, and dermis). There is a bias, however, such that clones are more likely to contain the cell types of spatially adjacent tissues such as cartilage/perichondrium and tendon/muscle connective tissue. It has been recently proposed that distinct proximodistal segments are established early in limb development; however our analysis suggests that there is not a strict barrier to cellular migration along the proximodistal axis in the early stage 19-22 limb buds. Finally, our data indicate the presence of a dorsal/ventral boundary established by stage 16 that is inhibitory to cellular mixing. This boundary is demarcated by the expression of the LIM-homeodomain factor lmx1b.

Genetic mapping of a 17q chromosomal region linked to obesity phenotypes in the IRAS family study

OBJECTIVE

Obesity is widely accepted to be influenced by both environmental and genetic factors. Several recent studies have used the positional cloning approach in an attempt to discover genes contributing to obesity. In the IRAS Family Study a genomewide scan was performed on 1425 individuals of Hispanic descent (90 extended pedigree families) to identify regions of the genome linked to obesity phenotypes.

METHODS

Nonparametric QTL linkage analysis was performed using a variance components approach. The genome scan was performed in two phases: an initial genome scan in 45 families and a replication scan in 45 families. Fine mapping and candidate gene analyses were also performed. General estimating equations (GEE1) and quantitative pedigree disequilibrium tests (QPDT) were used for association analysis of single SNP and haplotype data.

RESULTS

Evidence for linkage to obesity traits was observed in each scan on the long arm of chromosome 17. When data from both scans was combined, a region on chromosome 17q was identified with evidence of linkage to visceral adipose tissue (VAT; LOD 3.11), waist circumference (WAIST) (LOD 2.5) and body mass index (BMI) (LOD 2.81). Nine additional microsatellite markers were identified and genotyped on all Hispanic individuals, with a mean marker density of approximately 1 marker/3 cM. Evidence of linkage remained significant with LOD 3.05 for VAT, LOD 2.44 for BMI and LOD 1.92 for WAIST. Fine mapping analyses suggest the possibility of two different obesity loci. In addition, the LOD - 1 interval of the major VAT peak decreased from 83-108 to 95-111 cM. Three positional candidate genes under the peak: somatostatin receptor 2 (SSTR2), galanin receptor 2 (GALR2), and growth hormone bound protein receptor 2 (GRB2) were chosen for detailed evaluation. Multiple polymorphisms within each candidate were genotyped and tested for association with the obesity phenotypes. Little evidence of association was detected between polymorphisms and obesity traits.

CONCLUSION

In conclusion, replication of linkage and fine mapping suggest that a region on chromosome 17q contains a gene (or genes) that contributes to the genetic etiology of obesity with the strongest evidence for linkage to VAT. Candidate genes in the region do not appear to account for the evidence of linkage. Additional studies are necessary to identify the obesity-related polymorphisms.

A thorn in the side

This case demonstrates the importance of a thorough secondary survey in the management of ballistic injury. It also illustrates the need for systematic use of radiology, and the early management of life threatening conditions--regardless of whether their cause is known.

Optimum trephine length in the assessment of bone marrow involvement in patients with diffuse large cell lymphoma

BACKGROUND

The National Cancer Institute has recommended a bone marrow biopsy length of >/=20 mm for the staging and surveillance of patients with non-Hodgkin's lymphoma. However, there are few published data to support this recommendation, particularly the role of examining multiple levels.

PATIENTS AND METHODS

Bone marrow biopsies from 172 patients with newly diagnosed diffuse large cell lymphoma (DLCL) entered in two consecutive trials of the Australasian Leukaemia and Lymphoma Group were analysed. The original haematoxylin and eosin-stained trephine biopsy and two or more deeper sections cut at 0.1-0.2 mm intervals were assessed with respect to the morphology, extent and pattern of lymphomatous involvement. The rate of positive diagnosis was correlated with the length of the biopsy specimen and the number of sections examined.

RESULTS

Forty-seven biopsies (27%) demonstrated marrow involvement on examination of a mean of four trephine biopsy sections. The rate of positivity increased with the examination of multiple levels and correlated with increasing trephine length but was not dependent on the number of sites sampled. Twenty per cent of biopsies <20 mm in length were positive for lymphoma; this increased to 35% for biopsies >/=20 mm (P = 0.023).

CONCLUSIONS

Morphological bone marrow involvement in DLCL is optimally demonstrated by a 20-mm long trephine biopsy from a single site which is examined at multiple levels (four or more). This obviates the need for bilateral sampling, thereby reducing patient morbidity from the procedure. This study provides evidence to support the National Cancer Institute recommendations regarding trephine biopsy in the staging of DLCL, providing multiple levels are examined.

Diffuse large cell lymphoma and t(8;22) (q24;q11) in a patient with idiopathic CD4+ T-lymphopenia

We describe a unique case of a patient with a three-year history of idiopathic CD4(+) T cell lymphopenia (HIV negative) who presented with stage IV diffuse large cell non Hodgkin's lymphoma with t(8;22). Despite the severe lymphopenia, the patient tolerated intensive chemotherapy well and at 18 months, remains in complete remission.

Correlation between psychometric test scores and learning tying of surgical reef knots

We have investigated the correlation between the scores attained on a computerised psychometric test, measuring psychomotor aptitude and learning tying of a surgical reef knot. Fifteen surgical trainees performed a test of psychomotor aptitude (ADTRACK 2) from the MICROPAT testing system. They then performed a simple test of their ability to tie a surgical reef knot and were assessed by a panel of experts prior to embarking on a standardised course of instruction and practice session. The knot-tying test was repeated at the end of the day and the differences in average scores recorded. There was a significant correlation between the means of the differences in knot tying scores and ADTRACK 2 scores (r = -0.533, P < 0.05). Psychomotor abilities appear to be determinants of trainees' initial proficiency in learning to tie a surgical reef knot.

Developmental toxicity of lead-contaminated sediment to mallard ducklings

Sediment ingestion has been identified as an important exposure route for toxicants in waterfowl. The toxicity of lead-contaminated sediment from the Coeur d'Alene River Basin (CDARB) in Idaho was examined on posthatching development of mallard (Anas platyrhynchos) ducklings for 6 weeks. Day-old ducklings received either untreated control diet, clean sediment (24%) supplemented control diet, CDARB sediment (3,449 microg/g lead) supplemented diets at 12% or 24%, or a positive control diet containing lead acetate equivalent to that found in 24% CDARB. The 12% CDARB diet resulted in a geometric mean blood lead concentration of 1.41 ppm (WW) with over 90% depression of red blood cell ALAD activity and over threefold elevation of free erythrocyte protoporphyrin concentration. The 24% CDARB diet resulted in blood lead of 2.56 ppm with over sixfold elevation of protoporphyrin and lower brain weight. In this group the liver lead concentration was 7.92 ppm (WW), and there was a 40% increase in hepatic reduced glutathione concentration. The kidney lead concentration in this group was 7.97 ppm, and acid-fast inclusion bodies were present in the kidneys of four of nine ducklings. The lead acetate positive control group was more adversely affected in most respects than the 24% CDARB group. With a less optimal diet (mixture of two thirds corn and one third standard diet), CDARB sediment was more toxic; blood lead levels were higher, body growth and liver biochemistry (TBARS) were more affected, and prevalence of acid-fast inclusion bodies increased. Lead from CDARB sediment accumulated more readily in duckling blood and liver than reported in goslings, but at given concentrations was generally less toxic to ducklings. Many of these effects are similar to ones reported in wild mallards and geese within the CDARB.

Developmental toxicity of lead-contaminated sediment in Canada geese (Branta canadensis)

Sediment ingestion has recently been identified as an important exposure route for toxicants in waterfowl. The effects of lead-contaminated sediment from the Coeur d'Alene River Basin (CDARB) in Idaho on posthatching development of Canada geese (Branta canadensis) were examined for 6 wk. Day-old goslings received either untreated control diet, clean sediment (48%) supplemented control diet, or CDARB sediment (3449 microg/g lead) supplemented diets at 12%, 24%, or 48%. The 12% CDARB diet resulted in a geometric mean blood lead concentration of 0.68 ppm (ww), with over 90% depression of red blood cell ALAD activity and over fourfold elevation of free erythrocyte protoporphyrin concentration. The 24% CDARB diet resulted in blood lead of 1.61 ppm with decreased hematocrit, hemoglobin, and plasma protein in addition to the effects just described. The 48% CDARB diet resulted in blood lead of 2.52 ppm with 22% mortality, decreased growth, and elevated plasma lactate dehydrogenase-L (LDH-L) activity. In this group the liver lead concentration was 6.57 ppm (ww), with twofold increases in hepatic lipid peroxidation (thiobarbituric acid-reactive substances, TBARS) and in reduced glutathione concentration; associated effects included elevated glutathione reductase activity but lower protein-bound thiols concentration and glucose-6-phosphate dehydrogenase (G-6-PDH) activity. The kidney lead concentration in this group was 14.93 ppm with subacute renal tubular nephrosis in one of the surviving goslings. Three other geese in this treatment group exhibited calcified areas of marrow, and one of these displayed severe chronic fibrosing pancreatitis. Lead from CDARB sediment accumulated less readily in gosling blood and tissues than reported in ducklings but at given concentrations was generally more toxic to goslings. Many of these effects were similar to those reported in wild geese and mallards within the Coeur d'Alene River Basin.

Teleteaching--a practical and economical method of delivering surgical education

The Plymouth Regional MRCS Course was initiated in 1997 to support the College STEP learning course and supplement the BST clinical training programmes. The course is a comprehensive fortnightly day-release scheme, covering, over one year in 21 full days of teaching, the entire MRCS syllabus in a structured programme of learning.

Propofol anesthesia for invasive procedures in ambulatory and hospitalized children: experience in the pediatric intensive care unit

OBJECTIVES

To describe our experience with propofol anesthesia to facilitate invasive procedures for ambulatory and hospitalized children in the pediatric intensive care unit (PICU) setting.

METHODS

We retrospectively reviewed the hospital records of 115 children who underwent 251 invasive procedures with propofol anesthesia in our multidisciplinary, university-affiliated PICU during a 20-month period. All patients underwent a medical evaluation and were required to fast before anesthesia. Continuous monitoring of the patient's cardiorespiratory and neurologic status was performed by a pediatric intensivist, who also administered propofol in intermittent boluses to obtain the desired level of anesthesia, and by a PICU nurse, who provided written documentation. Data on patient demographics, procedures performed, doses of propofol used, the occurrence of side effects, induction time, recovery time, and length of stay in the PICU were obtained.

RESULTS

Propofol anesthesia was performed successfully in all children (mean age, 6.4 years; range, 10 days to 20.8 years) who had a variety of underlying medical conditions, including oncologic, infectious, neurologic, cardiac, and gastrointestinal disorders. Procedures performed included lumbar puncture with intrathecal chemotherapy administration, bone marrow aspiration and biopsy, central venous catheter placement, endoscopy, and transesophageal echocardiogram. The mean dose of propofol used for induction of anesthesia was 1.8 mg/kg, and the total mean dose of propofol used was 8.8 mg/kg. In 13% of cases, midazolam also was administered but did not affect the doses of propofol used. The mean anesthesia induction time was 3.9 minutes, and the mean recovery time from anesthesia was 28.8 minutes for all patients. The mean PICU stay for ambulatory and ward patients was 140 minutes. Hypotension occurred in 50% of cases, with a mean decrease in systolic blood pressure of 25%. The development of hypotension was not associated with propofol doses, the concomitant use of midazolam, or the duration of anesthesia, but was associated with older patient age. Hypotension was transient and not associated with altered perfusion. Intravenous fluid was administered in 61% of the cases in which hypotension was present. Respiratory depression requiring transient bag-valve-mask ventilation occurred in 6% of cases and was not associated with patient age, propofol doses, concomitant use of midazolam, or the duration of anesthesia. Transient myoclonus was observed in 3.6% of cases. Ninety-eight percent of procedures were completed successfully, and no procedure failures were considered secondary to the anesthesia. Patients, parents, and health care providers were satisfied with the results of propofol anesthesia.

CONCLUSIONS

Propofol anesthesia can safely facilitate a variety of invasive procedures in ambulatory and hospitalized children when performed in the PICU and is associated with short induction and recovery times and PICU length of stay. Hypotension, although usually transient, is common, and respiratory depression necessitating assisted ventilation may occur. Therefore, appropriate monitoring and cardiorespiratory support capabilities are essential. Propofol anesthesia in the PICU setting is a reasonable therapeutic option available to pediatric intensivists to help facilitate invasive procedures in ambulatory and hospitalized children.

The hypnic ("alarm clock") headache syndrome

Hypnic headache syndrome is a rare, sleep-related, benign headache disorder. We report 19 new cases (84% females) with follow-up data. The mean age at headache onset was 60.5 +/- 9 years (range 40-73 years). Headache awakened the patients from the night's sleep at a consistent time, usually between 1.00 and 3.00 a.m. (63%); three patients (16%) reported that identical headaches could occur also during daytime naps. Headache frequency was high, occurring more than 4 nights/week in 68% of the patients. Headache resolution occurred within 2 h in 68% of patients. Neurologic examination, laboratory studies, and brain imaging were unrevealing at the time of diagnosis. Headache severity largely remains unchanged or attenuates over time, but frequency may vary in either direction. Only one patient had spontaneous relief from headache. Four patients (24%) achieved permanent suppression of headache with medication, and two were able to abort individual headache attacks. Caffeine in a tablet or beverage was helpful in four patients. Lithium carbonate therapy caused side effects requiring cessation of treatment in four patients.

Activation of the 43 kDa inositol polyphosphate 5-phosphatase by 14-3-3zeta

The 43 kDa inositol polyphosphate 5-phosphatase (5-phosphatase) hydrolyzes and thereby inactivates the second messenger molecules inositol 1,4,5-trisphosphate -Ins(1,4,5)P3- and inositol 1,3,4,5-tetrakisphosphate in a signal terminating reaction. Recent studies have shown that the platelet protein pleckstrin forms a complex with the 43 kDa 5-phosphatase and activates Ins(1,4,5)P3 hydrolysis 2-fold [Auethavekiat, V., Abrams, C. S., & Majerus, P. W. (1997) J. Biol. Chem. 272, 1786-1790]. We now show that another platelet protein, 14-3-3zeta, forms a complex with the 43 kDa 5-phosphatase and thereby activates the hydrolysis of Ins(1,4,5)P3. Both pleckstrin and 14-3-3zeta contain one or more pleckstrin-homology domains, both are present in platelet cytosol, and both dimerize and form complexes with other signalling proteins. Purified platelet pleckstrin and 14-3-3zeta enhanced the rate of the hydrolysis of Ins(1,4,5)P3 by the 43 kDa 5-phosphatase 1.9- and 3.8-fold, respectively, but did not activate the 75 kDa 5-phosphatase. We have demonstrated that the mechanism of 5-phosphatase activation by 14-3-3zeta results from specific complex formation between the 43 kDa 5-phosphatase and 14-3-3zeta. Recombinant 43 kDa 5-phosphatase bound to recombinant glutathione S-transferase (GST)/14-3-3zeta fusion protein, but not GST alone, immobilized on glutathione-Sepharose. A potential 14-3-3 binding motif was located in the 43 kDa, but not the 75 kDa, 5-phosphatase. The motif "363RSESEE" is present in close proximity to the proposed catalytic domain of the 43 kDa 5-phosphatase. A synthetic peptide corresponding to the putative 14-3-3 binding motif demonstrated specific, saturable binding to purified 125I-14-3-3, with a Kd of 92 nM. In addition, platelet cytosolic 5-phosphatase bound to recombinant 14-3-3zeta immobilized on glutathione-Sepharose. Thus, 14-3-3zeta serves in human platelets to activate the 43 kDa 5-phosphatase and may thereby function to prevent generation of Ins(1,4,5)P3 -mediated calcium release in unstimulated platelets.

A family practice residency cervical screening project: perceived screening barriers

BACKGROUND AND OBJECTIVES

A community-based family practice residency program initiated a cervical screening project to provide free Pap smears to women who had not had one in 3 years. The research identified reasons why patients had not been screened within the past 3 years.

METHODS

A total of 214 consecutive participants in the free Pap smear clinic completed questionnaires. The questionnaire asked about reasons why screening had not occurred over the last 3 years.

RESULTS

Altogether, 65.4% of the study group reported cost-related factors as barriers to participation; 37.9% cited either scheduling concerns, fear, or embarrassment; and 36% cited misinformation issues about either screening recommendations, effectiveness of treatment, or disease presentation.

CONCLUSIONS

Strategies to increase participation in Pap smear screening clinics may include increasing availability of free or low-cost screening examinations, increasing time efficiency and scheduling flexibility of examinations, and making efforts to mitigate the fear and embarrassment associated with the exam.

An overview of the diagnosis and pharmacologic treatment of migraine

Migraine, an episodic headache disorder, is one of the most common complaints encountered by primary-care physicians and neurologists. Nevertheless, it remains underdiagnosed and undertreated. Rational migraine treatment necessitates an accurate diagnosis, identification and removal of potential triggering factors, and, frequently, pharmacologic intervention. Effective management also includes establishing realistic expectations, patient reassurance, and education. The choice of medication (abortive, symptomatic) for an acute attack depends on such factors as the severity of the attack, presence or absence of vomiting, time of onset to peak pain, rate of bioavailability of the drug, comorbid medical conditions, and side-effect profile. Effective agents for acute attacks include simple or combination analgesics, nonsteroidal anti-inflammatory drugs, ergot derivatives, selective serotonin agonists, and antiemetics. Opioid analgesics are unnecessary for most patients. The choice of preventive (prophylactic, interval) medication depends primarily on comorbid medical conditions and side-effect profile. Useful preventive agents include beta-adrenergic blockers, calcium channel blockers, tricyclic antidepressants, anticonvulsant medications, and serotonin antagonists.

Regulation of second messengers by the inositol polyphosphate 5-phosphatases

The inositol polyphosphate 5-phosphatases are an enlarging family of enzymes that terminate the signals generated by the phosphoinositide kinases and phospholipase C. Given the diverse signalling functions of both the polyphosphoinositides and Ins(1,4,5)P3, it is predicted that the 5-phosphatases will play a critical role in regulating many cellular events, in particular membrane trafficking and cell growth.

Antiarrhythmic and electrophysiological effects in-vivo of the major metabolite of Org 7797 found in canine and rodent liver homogenate preparations

Org 20781, the major metabolite of Org 7797 found in in-vitro experiments was examined for antiarrhythmic and electrophysiological effects in-vivo. Org 20781 (0.5-2.0mg kg-1, i.v.) inhibited the development of early ischaemia-induced arrhythmias in rats, suppressed spontaneous ventricular tachycardia (VT) in conscious dogs with 24-h old infarcts, and prevented electrical induction of VT in dogs with 5-6 day old infarcts, actions associated with slowing of conduction at all levels of the myocardium. Cardiac refractory periods were only modestly prolonged whilst repolarization was unchanged. Peak plasma levels of the parent compound (infused to total doses of 2-4 mg kg-1) associated with suppression of late arrhythmias were 6-18 microM, whilst the mean plasma elimination half-life (in normal dogs) was 107 min. It was concluded that the major metabolite has a similar antiarrhythmic and electrophysiological profile to the parent compound, is at least half as potent and may contribute to the therapeutic effects of Org 7797 administration.

Automobile air bag eye injuries

Until improvements in the design of air bags have minimized the risk of serious ocular trauma, practitioners must be alert to the possibility of severe eye damage any time the device is activated. Prompt ophthalmological referral and prompt treatment of any ocular injury can result in a lower incidence of permanent visual loss.

Diagnosis and treatment of cluster headache

Cluster headache (CH) is a rare form of headache occurring in both episodic and chronic forms. The painful attacks are short-lived, occur unilaterally, and are associated with signs and symptoms of autonomic involvement. Attacks frequently occur at night and can be precipitated by ingestion of alcohol. In the episodic form, attacks occur daily for some weeks followed by a period of remission. In the chronic form, attacks can continue for years. Inheritance is not a factor in CH. Treatment can be symptomatic or prophylactic. Agents used to treat individual attacks include inhalation of oxygen, rapidly acting forms of ergotamine and dihydroergotamine, and sumatriptan. Prophylactic treatment employs calcium-channel-blocking agents, methysergide, lithium, and corticosteroids. Surgical modalities, notably thermocoagulation of the gasserian ganglion, can provide relief in those who are resistant to medical management.

Comparative frequency-dependent effects of three class Ic agents, Org 7797, flecainide, and propafenone, on ventricular action potential duration

The frequency-dependent electrophysiological effects of three class Ic agents, Org 7797 (0.5-5 microM), flecainide (1-20 microM), and propafenone (1-10 microM), were investigated using isolated guinea pig papillary muscle. Transmembrane cellular action potentials were recorded using conventional microelectrode techniques at driving frequencies of 0.3, 1.0, and 2.0 Hz. In concentrations inducing similar frequency-dependent decreases in Vmax, both flecainide and propafenone shortened action potential duration (APD) at the two lower stimulation frequencies, whereas increasing the driving frequency to 2 Hz attenuated drug-induced APD shortening. In contrast, Org 7797 did not shorten APD at any stimulation frequency, and indeed APD lengthening was observed at 2.0 Hz. Increases in the effective refractory period (ERP) were seen at 1.0 and 2.0 Hz in the presence of Org 7797 and at 2.0 Hz in the presence of flecainide, but ERP was either unchanged (2.0 Hz) or shortened by propafenone. The rate of onset of sodium channel block was faster in response to propafenone compared to Org 7797 and flecainide. It was concluded that all three drugs may inhibit outward repolarising potassium currents, especially at higher stimulation frequencies. However, the concentrations of Org 7797 necessary to influence repolarisation may be closer to those required to induce sodium channel block compared to flecainide and especially propafenone. These differences may influence drug-induced effects on wavelength resulting in differences in antifibrillatory efficacy.

Comparison of two instructional methods on the levels of physiologic and psychologic stress as measured by blood cortisol and the State-Trait Anxiety Inventory

This study was designed to determine whether a systematic or nonsystematic instructional strategy affected the levels of physiologic and psychologic stress as measured by blood cortisol levels and the State-Trait Anxiety Inventory (STAI) in students in the postsecondary educational setting. A convenience sample consisting of 43 subjects was randomly assigned to either a systematic or nonsystematic teaching group. The blood cortisol and STAI were measured 1 and 2 weeks before the treatment and following the treatment on the day of the study. Results of the study demonstrated that there were differential posttreatment increases in the amount of physiologic stress, as measured by blood cortisol levels produced by either instructional method. However, between the control measurement 1 week before the treatment and the posttreatment measurement, there were no effects observed for the psychologic STAI measures for either group. Accounting for the circadian rhythm effect of cortisol, there was a significant "buffering effect" in stress experienced by the subjects in the systematic teaching group. More specifically, the nonsystematic teaching group experienced a 55.42% rate increase in cortisol compared to a 10.74% rate increase for the systematic teaching group which was statistically significant. The systematic teaching method may be more effective in preventing physiologic stress in the educational setting and possibly in the clinical practice of anesthesia nursing. Additionally, the results suggested that the STAI may be inappropriate when used as an index of stress in certain educational settings.

Effects of Org 7797 on early, late and inducible arrhythmias following coronary artery occlusion in rats and dogs

1. The class Ic steroidal antiarrhythmic agent, Org 7797, was compared with two other Ic agents, flecainide and propafenone for intravenous activity against ischaemia-related cardiac arrhythmias and for electrophysiological actions in vivo. In addition the haemodynamic effects of Org 7797 were assessed in greyhounds. 2. Org 7797 (0.5 mg kg-1) significantly reduced the expected incidence of early ischaemia-induced ventricular fibrillation (VF) in rats and greyhound dogs and at doses of 0.5-1.0 mg kg-1 antagonized reperfusion-induced arrhythmias. Comparative studies in rats showed Org 7797 to be 2-4 times more potent than flecainide or propafenone. 3. Org 7797 (0.5 mg kg-1) slowed intracardiac conduction in anaesthetized beagles and again was at least 2-4 times more potent than flecainide or propafenone. 4. Org 7797 (0.5 and 2.0 mg kg-1), flecainide (1.0 and 2.0 mg kg-1) or propafenone (0.5 and 2.0 mg kg-1), did not significantly prevent induction of tachyarrhythmias (VT) in dogs with 5-6 day old myocardial infarcts although all 3 drugs appeared to prevent induced VF. All 3 drugs (notably flecainide) did however reduce the VT rate. 5. All 3 drugs (1-2 mg kg-1) suppressed spontaneous tachyarrhythmias in conscious beagle dogs with 1-2 day old infarcts. Propafenone was the least effective. 6. In an antifibrillatory dose (0.5 mg kg-1), the major haemodynamic effect of Org 7797 was a 10% increase in peripheral vascular resistance. Stroke volume, cardiac output and coronary blood flow were unchanged. In therapeutic doses, Org 7797 was also less negatively chronotropic than flecainide.7. It was concluded that Org 7797 is a potent antifibrillatory agent which is haemodynamically well tolerated. Higher doses are required to suppress late ischaemia-induced tachyarrhythmias which suggest that its antifibrillatory effects are the consequence of an action other than, or in addition to, sodium channel block.

Comparison of the electrophysiological effects of Org 7797, disopyramide, mexiletine and propafenone in anaesthetized dogs with myocardial infarcts

1. The electrophysiological effects of intravenously administered Org 7797 were compared with those of disopyramide (class Ia), mexiletine (Ib) and propafenone (Ic) in anaesthetized dogs with 5-6 day-old left ventricular myocardial infarcts. 2. Org 7797 (0.5 mg kg-1) slowed conduction at all levels of the myocardium as shown by increases in St-A, AH, HV and QRS intervals, very modestly prolonged atrial and ventricular refractory periods and slightly shortened ventricular repolarization. Sinus node recovery time was increased whilst the RR interval was unchanged. A higher dose (2 mg kg-1) prolonged RR and rendered 5 out of 8 dogs unable to follow an atrial pacing stimulus of mean cycle length 322 ms. 3. Electrophysiological changes induced by propafenone (2 mg kg-1) were qualitatively similar to those of Org 7797 (0.5 mg kg-1). 4. Electrophysiological changes induced by mexiletine (2 mg kg-1) were small or insignificant. The most noticeable effect was a modest increase in the St-A interval and a slight shortening of ventricular repolarization. A higher dose (8 mg kg-1) additionally slowed conduction in the His-Purkinje system and in the ventricular myocardium. 5. Disopyramide (2 and 5 mg kg-1) prolonged all cardiac intervals including JTc, QTc and QT during pacing and prolonged cardiac refractory periods. 6. It was concluded that the electrophysiological profile of Org 7797 is more like that of the Ic agent propafenone than that of the class Ia and Ib drugs, disopyramide and mexiletine.

Effects of amiodarone on cardiac electrophysiology and inducibility of arrhythmias in chronically infarcted dogs: late arrhythmias, haemodynamics, and sympatholytic actions

The electrophysiological and antiarrhythmic effects of acute (2 and 10 mg/kg i.v.) and chronic (400 mg/day p.o. for 28 days) amiodarone (AM) treatment were compared in anaesthetised dogs with 5-6-day-old myocardial infarcts. Intravenous AM prolonged the RR interval, sinus node recovery time, the PR interval, and atrial to His conduction time by 36, 33, 25, and 36%, respectively. Corresponding increases after oral amiodarone were 50, 57, 12, and 26%. Atrial and His-Purkinje conduction times were unchanged. Atrial and ventricular refractory periods were increased especially after oral treatment. Oral AM additionally prolonged QRS, QT, and paced QT (by 4, 34, and 19%, respectively). Effects of oral AM on ventricular repolarisation and on the fast inward sodium current were confirmed in vitro. Both modes of AM administration protected against inducible arrhythmias, an effect that was more marked during normal sinus rhythm than during pacing in orally treated dogs. Oral amiodarone failed to protect against spontaneous late arrhythmias 24 h after infarction whilst both modes of administration noncompetitively inhibited isoprenaline-induced tachycardia. Oral AM reduced blood pressure (13%) and LV dP/dt/P (24%) whereas cardiac output was maintained by an increase in stroke volume. It was concluded that oral AM is haemodynamically well tolerated and that prolonged ventricular repolarisation enhanced by bradycardia together with sympatholytic actions may be important mechanisms for antiarrhythmic efficacy, whereas the mechanisms involved in i.v. efficacy are less clear but may depend, at least partly, on sympatholytic actions and perhaps (tentatively) on sodium channel block in Purkinje tissue.

Manifestations of migraine

Migraine is a disorder with multiple manifestations affecting the circulation, gastrointestinal tract, and the central nervous system. Involvement of the autonomic nervous system is responsible for many of the clinical features. An attack of migraine can vary from a fragment of the clinical spectrum to one with several phases and potentially permanent sequelae.

Voyager Radio Science Observations of Neptune and Triton

The Voyager 2 encounter with the Neptune system included radio science investigations of the masses and densities of Neptune and Triton, the low-order gravitational harmonics of Neptune, the vertical structures of the atmospheres and ionospheres of Neptune and Triton, the composition of the atmosphere of Neptune, and characteristics of ring material. Demanding experimental requirements were met successfully, and study of the large store of collected data has begun. The initial search of the data revealed no detectable effects of ring material with optical depth tau [unknown] 0.01. Preliminary representative results include the following: 1.0243 x 10(26) and 2.141 x 10(22) kilograms for the masses of Neptune and Triton; 1640 and 2054 kilograms per cubic meter for their respective densities; 1355 +/- 7 kilometers, provisionally, for the radius of Triton; and J(2) = 3411 +/- 10(x 10(-6)) and J(4) = -26(+12)(-20)(x10(-6)) for Neptune's gravity field (J>(2) and J(4) are harmonic coefficients of the gravity field). The equatorial and polar radii of Neptune are 24,764 +/- 20 and 24,340 +/- 30 kllometers, respectively, at the 10(5)-pascal (1 bar) pressure level. Neptune's atmosphere was probed to a pressure level of about 5 x 10(5) pascals, and effects of a methane cloud region and probable ammonia absorption below the cloud are evident in the data. Results for the mixing ratios of helium and ammonia are still being investigated; the methane abundance below the clouds is at least 1 percent by volume. Derived temperature-pressure profiles to 1.2 x 10(5) pascals and 78 kelvins (K) show a lapse rate corresponding to "frozen" equilibrium of the para- and ortho-hydrogen states. Neptune's ionosphere exhibits an extended topside at a temperature of 950 +/- 160 K if H(+) is the dominant ion, and narrow ionization layers of the type previously seen at the other three giant planets. Triton has a dense ionosphere with a peak electron concentration of 46 x 10(9) per cubic meter at an altitude of 340 kilometers measured during occultation egress. Its topside plasma temperature is about 80 +/- 16 K if N(2)(+) is the principal ion. The tenuous neutral atmosphere of Triton produced distinct signatures in the occultation data; however, the accuracy of the measurements is limited by uncertainties in the frequency of the spacecraft reference oscillator. Preliminary values for the surface pressure of 1.6 +/- 0.3 pascals and an equivalent isothermal temperature of 48 +/- 5 K are suggested, on the assumption that molecular nitrogen dominates the atmosphere. The radio data may be showing the effects of a thermal inversion near the surface; this and other evidence imply that the Triton atmosphere is controlled by vapor-pressure equilibrium with surface ices, at a temperature of 38 K and a methane mixing ratio of about 10(-4).

Comparative effects of the isomers of bepridil on isolated coronary and aortic arteries

The vasodilator actions of racemic bepridil were compared with those of its laevo-(l) and dextro-(d) rotatory isomers in isolated rabbit aorta and pig coronary artery. The actions of bepridil (B), (l) B and (d) B were further compared with those of drugs known to act either by blockade of calcium entry or to inhibit calmodulin in pig coronary artery. (l) B and (d) B were equipotent in relaxing tonic contractions induced by phenylephrine in rabbit aorta but (d) B was approximately twice as potent as (l) B in relaxing tonic contractions induced by potassium (K+). Both (d) B and (l) B relaxed K+-induced contractions in coronary artery and, in higher concentrations, inhibited and N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide (W7) were equipotent against both types of contraction whilst nifedipine and verapamil failed to reduce histamine-induced contractions. Both isomers of bepridil (like W7) shifted concentration-response curves to histamine in non-depolarized coronary artery in a noncompetitive manner. No potency differences were found between (l) B and (d) B in this tissues. It is concluded that intracellular actions, possibly calmodulin inhibition, play a substantial role in the vasodilator action of bepridil, a conclusion supported by the relative lack of stereospecificity shown by the bepridil isomers.

Somatosensory evoked potentials: lack of value for diagnosis of thoracic outlet syndrome

Twenty patients with thoracic outlet syndrome (TOS) seen at the Mayo Clinic between October 1984 and November 1985 were studied prospectively with routine nerve conduction studies, concentric needle examination, and bilateral median and ulnar somatosensory evoked potentials (SEPs). Results of nerve conduction studies and needle examination were abnormal in 30% of the patients, one patient having a reduced ulnar sensory nerve action potential amplitude and five others having neurogenic motor unit potential changes in the hand muscles. Ulnar SEPs were abnormal in three patients (15%), and median SEPs were abnormal in one patient, who also had abnormalities in ulnar SEPs. In patients with TOS, routine nerve conduction studies and needle examination were the most helpful electrophysiologic studies in excluding more common conditions. The routine use of ulnar SEPs in the evaluation of patients with TOS is probably not worthwhile.

Effects of diet-induced hypokalaemia on the efficacy of antiarrhythmic drugs against ventricular arrhythmias evoked by coronary artery ligation in the anaesthetised rat

The antiarrhythmic efficacies of intravenous quinidine (Q), disopyramide (D), prenylamine (P), bepridil (B), and practolol were compared in normokalaemic and dietary-induced hypokalaemic anaesthetised rats. Hypokalaemia markedly increased the severity of arrhythmias induced by coronary artery ligation and reduced the antiarrhythmic efficacy of all five drugs tested. After anaesthesia, hypokalaemia was associated with hypotension and bradycardia but not QTc prolongation. However, bradycardia was not seen in conscious hypokalaemic animals. Papillary muscles taken from hypokalaemic rats displayed a longer action potential duration but no increase in Vmax compared with tissue taken from normokalaemic animals. It is concluded that hypokalaemia in the rat causes electrophysiological disturbances which may contribute both to the observed exacerbation of ischaemia-induced arrhythmias and to the reduced efficacy of Q, D, P, and B. The reduced efficacy of practolol might be explained by other consequences of hypokalaemia.

The effects of bepridil, compared with calcium-channel inhibitors and calmodulin antagonists on both spontaneous activity and contractions induced by potassium or phenylephrine in rat portal vein

Bepridil is known to block calcium channels in some vascular tissues. Recent work has shown that bepridil also antagonises calmodulin. The present study attempted to more fully characterize the vasodilator actions of bepridil by comparing it with the known calcium channel blocking drugs, nifedipine, diltiazem, verapamil and flunarizine, the calmodulin inhibitors, trifluoperazine and W7 and propylmethylenedioxyindene, which is thought to act intracellularly, on rat portal vein. The relative activities of the test drugs were compared on spontaneous activity and on all components of the contractile responses to potassium and phenylephrine. Bepridil inhibited all components of the potassium and phenylephrine responses equally, actions similar to those of the intracellular acting drugs. The exception to this was trifluoperazine which also exerted alpha-adrenoceptor blocking actions. In contrast the calcium channel blocking drugs, with the exception of verapamil, inhibited the tonic component of both spasmogen responses more than the phasic component. Bepridil like the intracellular acting drugs, but unlike the calcium channel blockers, markedly increased the frequency of spontaneous contractions whilst reducing amplitude. It is concluded that the profile of bepridil on rat portal vein more closely resembles that of intracellularly acting drugs than that of classical calcium channel inhibitors.

Comparative electrophysiological effects of disopyramide and bepridil on rabbit atrial, papillary, and Purkinje tissue: modification by reduced extracellular potassium

The electrophysiological actions of bepridil were compared with those of disopyramide in rabbit atrial, Purkinje, and papillary muscles in both normokalaemic (5.6 mM K+) and low K+ medium. In normokalaemic medium, the major electrophysiological effects of bepridil (10-40 microM) were a reduction in the maximum rate of rise of phase 0 of the action potential (MRD) of atrial and Purkinje fibres and prolongation of the atrial action potential duration (APD). Higher concentrations (40-100 microM) reduced MRD of papillary muscle without markedly affecting APD. Disopyramide (40-100 microM) reduced MRD and prolonged APD in similar concentrations in all three tissues. Reducing extracellular (EC) K+ to 2.8 mM decreased the effects of bepridil on MRD in all tissues but only significantly reduced the response to disopyramide in papillary muscle. Enhancement of APD prolongation by disopyramide in all tissues resulted when EC K+ was reduced, whereas only papillary muscle APD showed a marked prolongation in response to bepridil. These results demonstrate that the class I effect of bepridil is highly K+ dependent. It may be expected that QTc prolongation produced by both these drugs will be more marked in patients with low serum potassium levels.

Surgical treatment of chronic cluster headache

Chronic cluster headache, also known as chronic migrainous neuralgia, is frequently unresponsive to medical management. Although neuronal factors may be involved in the pathogenesis of this form of recurrent hemicranial pain, vasodilatation within the distribution of the trigeminal nerve is believed to be important. Attempts to provide relief by surgical means have primarily involved interruption of the vasodilator pathways of the greater superficial petrosal nerve and the sphenopalatine ganglion. A more direct approach of interrupting the pain pathways of the trigeminal nerve has been attempted sporadically for more than 50 years. Recent interest in the role of substance P in the production of pain in cluster headache suggests that trigeminal ablative procedures might have a dual role in the relief of medically intractable cases. Among 26 patients who underwent posterior fossa trigeminal sensory rhizotomy or percutaneous radio-frequency trigeminal gangliorhizolysis at our institution, relief of pain was excellent in 14 (54%), fair to good in 4 (15%), and poor in 8 (31%).

Antiarrhythmic activity of 17 beta-aminoestratrienes. Comparison of 3-ols and 3-acetates with the corresponding 3-(3-amino-2-hydroxypropyl) ethers

The antiarrhythmic efficacy of 17 beta-amino- and 17 beta-amino-16 alpha-hydroxyestratrien-3-ols and 3-acetates (group 1) was compared with the efficacy of corresponding 3-[2-hydroxy-3-(isopropylamino)propyl] and 3-[2-hydroxy-3-(tert-butylamino)propyl] ethers (group II), substituents which are usually associated with beta-adrenoceptor blocking activity. Group I compounds exerted potent antiarrhythmic activity against both aconitine-induced arrhythmias in mice and ischemia-induced arrhythmias in rats and reduced the maximum following frequency of isolated guinea pig atria. Electrophysiological studies indicated that their mechanism of action is due to an ability to reduce the fast inward sodium current in cardiac cells (class I antiarrhythmic action). Group II compounds were inactive in the aconitine and atrial tests and electrophysiological studies confirmed that they were devoid of class I activity. However, these compounds, like both class I antiarrhythmic and beta-adrenoceptor blocking drugs, were active against ischemia-induced arrhythmias. Group II compounds, unlike group I compounds, exerted nonspecific beta-adrenoceptor blocking actions, which may account for their activity in the rat test. It was concluded that introduction of the 3-substituted ether group did not confer any advantage over the parent 3-ol or 3-acetate compounds.

Comparative effects of bepridil and verapamil on isolated coronary and systemic vascular and cardiac muscle

The relaxant effects of the antianginal agent bepridil, a drug with calcium antagonistic actions, and verapamil on isolated pig coronary (C) and rabbit aortic (A) smooth muscle were compared. Both drugs competitively antagonised calcium in Tris buffered but not in bicarbonate buffered medium. Both agents relaxed K+-depolarised C and inhibited contractile responses to noradrenaline plus anoxia. Bepridil was approximately 10 fold less potent than verapamil. The two drugs exerted similar calcium antagonistic effects in guinea pig papillary muscle but showed dissimilar profiles in atrial muscle in that responses in the presence of bepridil appeared to be frequency dependent. It is concluded that bepridil inhibits responses to anoxia and competitively antagonises calcium in vascular smooth muscle. On atrial tissue, bepridil, unlike verapamil, appears to exert additional actions possibly involving other ion channels.