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PubMed1994

Ventricular beats induce variations in cycle length of rapid (type II) atrial flutter in humans. Evidence of leading circle reentry.

BACKGROUND: Slight variation in cycle lengths of common and rapid atrial flutter in humans is an established phenomenon, but its mechanisms have not been completely clarified. In a previous study, we demonstrated that in common atrial flutter the variations in atrial cycle length were due to atrial stretch affecting the revolution time of a reentrant circuit. In the present study, we investigate the nature of atrial cycle length variations in the rapid type of human atrial flutter. METHODS AND RESULTS: Atrial interval variations of 17 episodes of rapid atrial flutter in 14 patients were investigated by measuring the sequence of atrial intervals from intraesophageal or intra-atrial leads and the onset of QRS complexes from a surface lead (V1). To study whether interval variation in flutter cycle was related to ventricular activity, a phase plot was constructed in which the flutter cycle length was plotted against the time after the previous QRS complex. This showed that the interval fluctuations were strictly coupled to the moment of ventricular activation. After the onset of the QRS complex, the rapid atrial flutter interval gradually decreased by an average of 4.1% (P < .001) and reached a minimum value after 300 to 600 milliseconds. Thereafter, the intervals increased again until the next ventricular beat occurred. In 10 patients developing both common and rapid atrial flutter, two different phase relations were found. Whereas during common atrial flutter the atrial interval increased after the QRS complex, it decreased during rapid atrial flutter. In three patients, intra-atrial pressure was recorded together with the electrical activity during both common and rapid atrial flutter episodes. This showed that variations in atrial flutter cycle length were associated with the rise of atrial pressure during ventricular contraction. CONCLUSIONS: These findings indicate a role of contraction-excitation feedback caused by atrial stretch after a ventricular activation. The shortening of the atrial interval after the onset of the QRS complex as found in patients during rapid atrial flutter can be explained by stretch-induced shortening of atrial refractoriness and consequent shortening of the revolution time of a functionally determined intra-atrial circuit.

Aged↗
PubMed2006

Ca2+-dependent rapid Ca2+ sensitization of contraction in arterial smooth muscle.

Ca(2+) ion is a universal intracellular messenger that regulates numerous biological functions. In smooth muscle, Ca(2+) with calmodulin activates myosin light chain (MLC) kinase to initiate a rapid MLC phosphorylation and contraction. To test the hypothesis that regulation of MLC phosphatase is involved in the rapid development of MLC phosphorylation and contraction during Ca(2+) transient, we compared Ca(2+) signal, MLC phosphorylation, and 2 modes of inhibition of MLC phosphatase, phosphorylation of CPI-17 Thr38 and MYPT1 Thr853, during alpha(1) agonist-induced contraction with/without various inhibitors in intact rabbit femoral artery. Phenylephrine rapidly induced CPI-17 phosphorylation from a negligible amount to a peak value of 0.38+/-0.04 mol of Pi/mol within 7 seconds following stimulation, similar to the rapid time course of Ca(2+) rise and MLC phosphorylation. This rapid CPI-17 phosphorylation was dramatically inhibited by either blocking Ca(2+) release from the sarcoplasmic reticulum or by pretreatment with protein kinase C inhibitors, suggesting an involvement of Ca(2+)-dependent protein kinase C. This was followed by a slow Ca(2+)-independent and Rho-kinase/protein kinase C-dependent phosphorylation of CPI-17. In contrast, MYPT1 phosphorylation had only a slow component that increased from 0.29+/-0.09 at rest to the peak of 0.68+/-0.14 mol of Pi/mol at 1 minute, similar to the time course of contraction. Thus, there are 2 components of the Ca(2+) sensitization through inhibition of MLC phosphatase. Our results support the hypothesis that the initial rapid Ca(2+) rise induces a rapid inhibition of MLC phosphatase coincident with the Ca(2+)-induced MLC kinase activation to synergistically initiate a rapid MLC phosphorylation and contraction in arteries with abundant CPI-17 content.

Adrenergic alpha-Agonists↗
PubMed1994

Validity of rapid cycling as a course specifier for bipolar disorder.

OBJECTIVE: This study's aim was to test the validity of rapid cycling, defined by criteria consistent with those proposed in the DSM-IV draft, as a course specifier for bipolar disorder. METHOD: The study was conducted at a university center for affective disorders on patients fulfilling Research Diagnostic Criteria for bipolar disorder. Thirty-seven rapid-cycling patients, i.e., patients with at least four affective episodes during the previous year, were compared with 74 nonrapid-cycling patients on several demographic and clinical variables. All patients were then followed up prospectively for 2-5 years by monthly personal interviews. RESULTS: The rapid-cycling group was significantly older and had a significantly longer illness duration than the nonrapid-cycling group but did not have a significantly higher percentage of women or frequency of current hypothyroidism. During each year of follow-up, the mean number of affective episodes and the percentage of patients with at least four affective episodes were significantly higher among rapid-cycling patients. Rapid-cycling patients with a pole-switching pattern during the year preceding intake were significantly more likely than other rapid-cycling patients to have at least four affective episodes during each of the first 4 years of follow-up. CONCLUSIONS: These findings support the practical usefulness of rapid cycling as a course modifier for bipolar disorder, since it identifies a patient subgroup with a high recurrence rate. The predictive value of the modifier may be enhanced by the requirement of a pole-switching pattern. Since no external (i.e., unrelated to course) validator was found, the idea that rapid cycling represents one extreme of a continuum of episode frequency in bipolar disorder remains viable.

Adult↗
PubMed1989

Rapid as well as delayed inhibitory effects of glucocorticoid hormones on pituitary adrenocorticotropic hormone release are mediated by type II glucocorticoid receptors and require newly synthesized messenger ribonucleic acid as well as protein.

Glucocorticoid hormones suppress the release of ACTH by the anterior pituitary gland: rapid feedback inhibits hormone secretion within 30 min of steroid application, delayed feedback is most effective at 1-2 h, and slow feedback becomes manifest in several hours. The aim of the present study was to determine the type of glucocorticoid receptor that mediates the rapid and delayed feedback actions of glucocorticoids and whether genomic activation occurs during the rapid and delayed time domains. Rat anterior pituitary cell columns were perfused with Dulbecco's minimum essential medium, 41-residue CRF (10(-9) M) was used as the secretagogue, which stimulated ACTH secretion to a peak of about 8- to 10-fold of basal release. The amount of ACTH released upon repeated 5 or 10 min stimulation with CRF was constant. Treatment with 10(-7) M corticosterone for 20 min immediately before and for 10 min during stimulation with CRF reduced ACTH release by about 50% (rapid feedback), while at 1 h and 2 h after the initial exposure to corticosterone the secretory response was 33% and 15% of control, respectively. The effect of corticosterone was prevented by the type II glucocorticoid/progesterone antagonist RU 38486 (10(-6) M). The selective type II receptor agonist RU 28362 (10(-7) M) was even more potent than corticosterone in inhibiting ACTH release; the time course of action was similar. When actinomycin D (10(-4) M) was applied in conjunction with RU28362 or corticosterone, no inhibitory effects appeared up to 2 h after the exposure to steroid. Puromycin (10(-4) M), given during and for 1 h after the administration of the steroid prevented the rapid as well as the delayed (1 h) inhibitory action of RU28362. When puromycin was removed from the system, a 75% inhibition of stimulated ACTH release developed at 2 h after the application of the steroid, indicating that translatable messenger RNA (mRNA) was still present in the cells. Cycloheximide (10(-4) M) was only partially effective at inhibiting rapid or delayed feedback, and increasing its concentration impaired the ACTH response to CRF-41. In summary, at the pituitary level the rapid as well as the delayed feedback inhibition of ACTH secretion by adrenal corticoids is exerted via type II glucocorticoid receptors. Furthermore, both rapid and delayed feedback require the synthesis of new mRNA and protein.

Adrenocorticotropic Hormone↗
PubMed1993

Differential effects of glucose stimulation upon rapid pulses and ultradian oscillations of insulin secretion.

To determine the effect of glucose stimulation on the rapid 8- to 15-min pulses and the ultradian 80- to 170-min oscillations of insulin secretion, peripheral concentrations of glucose, insulin, and C-peptide were measured at 2-min intervals over 2 h (i.e. rapid experiments), at 15-min intervals over 8-20 h (i.e. ultradian experiments) in 17 normal subjects during saline infusion, or during constant glucose infusion at a rate of 3 mg/(kg.min) (i.e. low dose) or 6 mg/(kg.min) (i.e. high dose). In the ultradian experiments, insulin secretory rates (ISR) were calculated by deconvolution of the plasma C-peptide concentrations. Significant oscillations with 125- to 166-min periods were detected in all glucose and ISR profiles. The numbers of ISR oscillations per 24 h were similar during saline infusion and low and high dose glucose infusion. In contrast, the amplitude of the ISR peaks increased progressively from 14 +/- 1 pmol/min during saline infusion to 50 +/- 7 pmol/min and further to 97 +/- 9 pmol/min during low and high dose glucose infusions, respectively. When expressed as percent increment, the amplitude of the ISR oscillations increased significantly from 31 +/- 5% during saline infusion to 41 +/- 4% during low dose glucose infusion and 44 +/- 3% during high dose glucose infusion (P < 0.05). In all profiles obtained from the 2-min sampling experiments, rapid pulses of glucose, insulin, and C-peptide were apparent. The number of insulin pulses during saline and glucose infusions corresponded to a mean periodicity of 10 min. The amplitude of these rapid insulin pulses increased from 17.3 +/- 2.9 to 39.8 +/- 11.8 pmol/L (P < 0.01) in response to glucose. In contrast to the ultradian oscillations, the relative amplitude of the rapid insulin pulses decreased significantly from 28.8 +/- 3.4% during saline infusion to 13.6 +/- 1.6% during high dose glucose infusion (P < 0.01). Our findings demonstrate that the pancreatic response to glucose stimulation is different for the rapid pulses and the ultradian oscillations. When the rate of glucose stimulation is increased, the absolute amplitude of both the rapid pulses and the ultradian oscillations increases. However, when expressed as percent increment, the amplitude of the rapid pulses decreases during glucose stimulation, whereas the amplitude of the ultradian oscillations increases. These findings suggest that the two oscillatory modes have a different origin and physiological significance.

Activity Cycles↗
PubMed2005

Rapid tests for detection of viral markers in blood transfusion.

Since the early 1990s, rapid tests have been available for detection of HIV infection. They were intended for field diagnosis, emergency and home testing. In addition, rapid tests for anti-HIV, hepatitis B surface antigen and antihepatitis C virus have been used for blood screening in many resource-poor areas to save resources and overcome lack of funding, equipment and electrical supply. The performance of rapid tests varies widely but some have sensitivity and specificity levels that meet standards established by enzyme immunoassays for anti-HIV. Compared with genomic detection of hepatitis B virus, hepatitis B surface antigen rapid tests and enzyme immunoassays have insufficient sensitivity. The clinical consequences of this performance deficit remain to be clarified. Anti-hepatitis C virus rapid tests detect chronically infected individuals who are viremic, however, further studies are required to fully assess their performance. In settings where few blood donations are collected and equipment is unavailable, rapid tests provide a flexible, technically undemanding and relatively inexpensive approach to ensuring a safer blood supply. When utilized for predonation screening in areas of high endemicity of viral markers, rapid tests provide the means to limit blood bag wasting, store only clinically usable blood and inform and counsel deferred donors. As with any laboratory assay, adequate training and sustained quality assurance programs are critical to maintain a safe supply of blood. As a means of achieving a safe blood supply, rapid tests for viral markers and nucleic acid testing have a place next to classic enzyme immunoassays in the definition of strategies that are adapted to a setting's epidemiology, the size and type of donor base, equipment, staff training and resources.

Blood↗
PubMed2006

Rapid antigen detection testing in diagnosing group A beta-hemolytic streptococcal pharyngitis.

Group A beta-hemolytic streptococcus (GABHS) is the most common bacterial cause of acute pharyngitis. Clinical criteria alone are not reliable enough to diagnose GABHS pharyngitis. Microbiological-testing is required for correct diagnosis. Although a throat swab culture remains the gold standard for documenting the presence of GABHS, a significant disadvantage of the culture is the delayed time of 1-2 days to obtain results. Most rapid antigen detection tests can provide results in less than 15 min. Rapid identification and treatment of patients with GABHS pharyngitis can reduce the risk of the spread of disease, may shorten the duration of symptoms, decrease the incidence of suppurative complications, decrease the amount of time lost from school/work, decrease the inappropriate use of antibiotics, reduce patient/parent dissatisfaction and alleviate the need for costly follow-up visits. All rapid antigen detection tests involve extraction of the group-specific carbohydrate antigen from the GABHS cell wall and identification of the antigen by an immunological reaction. There are numerous rapid antigen detection testing methods, namely latex agglutination, enzyme immunoassay, optical immunoassay, chemiluminescent DNA probes and PCR methods. Most of the rapid antigen detection tests that are currently in use have an excellent specificity of greater than 95% and a sensitivity of greater than or equal to 90%. Owing to the high specificity of the rapid antigen detection tests, a positive rapid antigen detection test is accepted as adequate for the diagnosis of GABHS pharyngitis. Conversely, confirmation of a negative antigen detection test with a throat culture result is necessary, unless the physician has ascertained in his/her practice that the sensitivity of the rapid antigen test used is comparable with that of a throat culture.

Antigens, Bacterial↗
PubMed2001

Exacerbation of traumatically induced axonal injury by rapid posthypothermic rewarming and attenuation of axonal change by cyclosporin A.

OBJECT: Although considerable attention has been focused on the use of posttraumatic hypothermia, little consideration has been given to the issue of posthypothermic rewarming and its potentially damaging consequences. In this communication, the authors examine the issue of rapid posthypothermic rewarming compared with gradual rewarming while exploring the potential utility of cyclosporin A (CsA) administration for attenuating any rapid rewarming-induced axonal change. METHODS: Male Sprague-Dawley rats were subjected to impact-acceleration injury and then their body temperature was lowered to 32 degrees C for 1 hour postinjury. After hypothermia, rewarming to normothermic levels was accomplished either within a 20-minute period (rapid rewarming) or over a 90-minute period (slow rewarming). Some animals in the rapid rewarming group received intrathecal infusion of either CsA or its vehicle, whereas the rats in the slow rewarming group received vehicle alone. Both the CsA and its vehicle were administered immediately before initiation of rewarming. Twenty-four hours postinjury the animals' brains were processed for visualization of amyloid precursor protein (APP), a marker of traumatic axonal injury. The APP-positive axonal density in the gradually rewarmed group receiving vehicle was statistically significantly reduced in comparison with the rapidly rewarmed, vehicle-treated group. For the group undergoing rapid rewarming and treatment with CsA, a statistically significant reduction was also found in the density of the APP profiles compared with the rapidly rewarmed, vehicle-treated group. CONCLUSIONS: The results of this study show that rapid rewarming exacerbates traumatically induced axonal injury, which can be significantly attenuated by administering CsA.

Amyloid beta-Protein Precursor↗
PubMed2000

["Rapid" serology for the diagnosis of Helicobacter pylori infection. Evaluation of its accuracy compared with a gold-standard and its concordance with "classic" serology].

AIM: To prospectively evaluate the validity of a rapid office-based diagnostic serological test (using capillary blood) in our population, taking as reference a combination of standard diagnostic methods, as well as to compare the results of this technique with those of "classic" serological tests (using venous blood). PATIENTS AND METHODS: We prospectively studied 39 consecutive patients with symptoms of the upper digestive tract who had undergone oral gastroscopy. Gastric biopsies were taken for histology and rapid urease testing, and a 13C-urea breath test was performed. An enzyme-linked immunoassay that detects IgG antibodies against Helicobacter pylori was used as a "classic" serological test and the commercial kit FlexPack HP was used as a "rapid" serological test. The endoscopist, the pathologist and those responsible for reading the rapid urease test, the 13C-urea breath test and both serological tests did not know the results of the other diagnostic methods. Patients were considered H. pylori positive when at least two of the three validated tests (rapid urease test, histology, and 13C-urea breath test) revealed infection and were considered free of infection when all tests were negative. RESULTS: Thirty-nine patients were studied. Thirty-eight per cent were male (mean age 48 +/- 15 years). The prevalence of H. pylori infection detected by the gold standard was 69.2%. The sensitivity and specificity of the "classic" serological test was 96% 95% (CI: 79-99) and 91% (59-100). "Rapid" serological testing was positive in nine patients, negative in 28 and indeterminate in two. A single digital puncture was sufficient in 80% of the patients, 15% needed two and 5% needed three. Most patients (77%) had no preference for either type of serological test while 20.5% preferred digital puncture and 2.5% venous puncture. The sensitivity, specificity, positive predictive value and negative predictive value were 31% (16-50), 91% (59-100), 89% (52-100) and 36% (19-56) respectively. Sensitivity was unaffected by age but specificity was lower in patients older than 40 years (89% vs. 100%; McNemar's test: 8; p < 0.01). Kappa's coefficient between the "classic" and the "rapid" serological tests was 0.16 (SE 0.1) and McNemar's test was 12.2 (p < 0.001), which indicates that the prevalence of infection diagnosed by both methods was not homogeneous. CONCLUSION: The "rapid" office-based serological test used in our study is of insufficient diagnostic accuracy to be used in clinical practice to identify H. pylori infection.

Enzyme-Linked Immunosorbent Assay↗
PubMed2003

A study of the myocardial protective effect of rapid cooling based on intracellular Ca, intracellular pH, and HSP70.

OBJECTIVE: It has been reported that rapid cooling of the heart during normothermic coronary circulation at reperfusion after ischemia promotes early recovery of cardiac function due to the positive inotropic effects on the myocardium produced by cooling. The aim of the present study was to investigate the myocardial protective effect of rapid cooling by measuring heat shock protein (HSP) levels and examining the relationship between cardiac function, intracellular Ca concentration, and intracellular pH after rapid cooling. METHODS: Isolated perfused rat hearts were subjected to ischemia for 60 minutes at a myocardial temperature of 37 degrees C. One group of hearts (group R) was subjected to 3 minutes of rapid cooling (</=4 degrees C) 3 minutes after reperfusion was started. The other hearts (group C) were not cooled. Myocardial protection was then compared in the two groups by measuring heart rate, coronary flow, left ventricular contraction, intracellular Ca concentration (fura-2 fluorescence), and intracellular pH (BCECF-AM fluorescence) and examining HSP70 by western blot. RESULTS: (1) Left ventricular contraction was 105+/-0.05% of the pre-ischemia value in group R after rapid cooling, whereas recovery was poor in group C (63+/-2%). (2) The intracellular Ca concentration in group R rose to 141+/-8% of the pre-ischemia value during ischemia, but decreased to 101+/-3% at reperfusion after rapid cooling. In group C, the Ca concentration was 144+/-4% of the pre-ischemia value during ischemia and rose further to 156+/-6% at reperfusion. (3) In group R, the intracellular pH was 6.85+/-0.05 during ischemia and rose after reperfusion was started, but after rapid cooling, decreased again to 7.43+/-0.02 after 60 minutes reperfusion. In group C, the pH was 6.88+/-0.06 during ischemia and rose to 7.90+/-0.09 60 minutes after reperfusion was started. (4) HSP70 was detected in both groups, but the concentration (luminescence) was lower in group R than in group C. CONCLUSION: Rapid cooling reduces myocardial injury by preventing intracellular Ca overload at reperfusion via inhibition of the Na(+)/Ca(2+) exchanger and also decreases the appearance of HSPs, the so-called homeostasis proteins. (Ann Thorac Cardiovasc Surg 2003; 9: 301-6)

Analysis of Variance↗
PubMed2006

Redirecting the growth pattern with rapid maxillary expander and chin cup treatment: changing breathing pattern from oral to nasal.

AIM: This study was undertaken to assess the possibility of redirecting the growth pattern by using rapid maxillary expansion and a light-force chin cup for a short period of time, with limited patient cooperation, during the pre-growth and growth-spurt stages. METHODS: The study included a series of 60 patients, 24 males and 36 females from 7 to 14 years of age, with crossbite or midfacial deficiencies. Treatment involved wearing a chin cup 24 hours a day to force mouth closure during rapid maxillary expansion activation, which was 2 turns per day to rapidly expand the midpalatal suture and enhance nasal breathing. Lateral cephalograms and intraoral and facial photographs were taken 2 years before treatment, at the time of rapid maxillary expansion, 3 weeks following rapid maxillary expansion activation, 3 months after the cessation of rapid maxillary expansion activation, and 1 to 3 years post-rapid maxillary expansion activation. RESULTS: Despite the severity, the crossbite would always improve within 21 days following rapid maxillary expansion activation. The cephalograms and photographs demonstrated forward movement of the nasal bridge and maxilla, with backward rotation of the mandible. The bite depth remained nearly the same as pretreatment. CONCLUSION: The results suggested that 24 hours of light-force chin cup wear, while expanding the midpalatal suture, is the major factor to force mouth closure and enhance nasal breathing. As a result, there is advancement of the maxilla, avoidance of tongue encroachment upon the mandible, and deceleration of horizontal mandibular growth.

Adolescent↗
PubMed2006

Absence of rapid eye movement sleep behavior disorder in 11 members of the pallidopontonigral degeneration kindred.

BACKGROUND: Rapid eye movement sleep behavior disorder (RBD) is a parasomnia that is manifested by dream enactment behavior. The electrophysiologic substrate for RBD on polysomnography is rapid eye movement sleep without atonia. Rapid eye movement sleep behavior disorder likely stems from neuronal network dysfunction in the brainstem, although it is not yet clear which specific networks are involved. Rapid eye movement sleep behavior disorder is often associated with the sporadic synucleinopathies but rarely associated with the sporadic tauopathies. There are no reports on the possible association of rapid eye movement sleep without atonia and RBD with any familial tauopathy. OBJECTIVE: To characterize the clinical sleep and polysomnography features in a kindred with a familial tauopathy. METHODS: We performed standard polysomnography in 11 members of the pallidopontonigral degeneration kindred irrespective of any sleep-related complaints. Neuropathologic findings were analyzed in those who subsequently underwent autopsy. RESULTS: Six affected and 5 genealogically at-risk family members were studied. None of the 11 had a history of dream enactment behavior. Nine of the 11 members attained sufficient rapid eye movement sleep on polysomnography, and the electrophysiologic features of rapid eye movement sleep without atonia and behavioral manifestations of RBD were absent in all subjects. Neuropathologic examination of 4 affected individuals revealed marked nigral degeneration in 3 along with mild degenerative changes in the locus coeruleus, pontine nuclei and tegmentum, and medullary tegmentum. CONCLUSIONS: These findings argue against nigral degeneration being the primary cause of RBD. The absence of the historical, electrophysiologic, and behavioral manifestations of RBD in this kindred provides further evidence that RBD is rare in the sporadic and familial tauopathies. The difference in frequencies of RBD associated with the synucleinopathies compared with the tauopathies suggests differences in the selective vulnerability of brainstem circuits between the synucleinopathies and tauopathies.

Adult↗
PubMed1998

Use of a rapid intraoperative parathyroid hormone assay in the surgical management of parathyroid disease.

OBJECTIVE: To evaluate the utility of a rapid intraoperative parathyroid hormone (PTH) immunoradiometric assay in the surgical management of parathyroid disease, particularly with reference to limiting extent of cervical exploration. DESIGN: Nonrandomized prospective study. SETTING: Academic tertiary care center. PATIENTS: Forty-three consecutive patients undergoing parathyroid exploration for adenoma or hyperplasia had rapid PTH assays performed from blood drawn at induction and 7 minutes after resection of all hyperfunctioning parathyroid tissue. OUTCOME MEASURES: Excision of all hyperfunctioning parathyroid tissue as assessed by bilateral neck exploration, postoperative normalization of serum calcium and PTH levels, and resolution of clinical symptoms. RESULTS: The intraoperative rapid PTH assay accurately reflected whether all hyperfunctioning parathyroid tissue was excised in every patient. In 41 patients, all hyperfunctioning parathyroid tissue was resected at the time of surgery and confirmed by a corresponding decrease in the intraoperative postexcision rapid PTH determination as well as by subsequent normalization of postoperative serum calcium and PTH levels and resolution of clinical symptoms. In 2 patients, the postexcision rapid PTH assay determination was not consistent with removal of all hyperfunctioning parathyroid disease and both patients demonstrated persistent hyperparathyroidism postoperatively. CONCLUSIONS: The intraoperative rapid PTH assay may be of significant benefit in permitting directed unilateral parathyroid explorations for adenoma when combined with preoperative localization with a technetium-99m sestamibi scan. Additionally, the rapid PTH assay has proved to be of benefit in confirming excision of all hyperfunctioning parathyroid tissue in patients with multiple gland hyperplasia, particularly those who may harbor ectopic parathyroid tissue.

Adenoma↗
PubMed2003

The long-term course of rapid-cycling bipolar disorder.

BACKGROUND: Rapid cycling among patients with bipolar affective disorders is important because of its implications for long-term prognosis and for the use of antidepressants. To our knowledge, no prospective study has, as yet, described the course of this phenomenon beyond 5 years. METHODS: From 345 patients with bipolar I or bipolar II disorder followed up for a mean (SD) of 13.7 (6.1) years as part of the National Institute of Mental Health Collaborative Depression Study, 89 (25.8%) were identified who, during 1 or more years of follow-up, manifested a pattern that met DSM-IV criteria for rapid cycling. These patients were compared with the remaining bipolar patients by demographics, overall affective morbidity, morbidity during specific treatment conditions, and the likelihood of suicidal behavior. Analyses assessed whether the use of tricyclic antidepressants for depressive symptoms was associated with the persistence of rapid cycling or with tendencies to switch from depressive to manic or hypomanic phases. RESULTS: The 89 patients who showed a rapid cycling pattern were significantly more likely to have had an illness onset before 17 years of age and were more likely to make serious suicide attempts. In 4 of 5 cases, rapid cycling ended within 2 years of its onset. Resolutions were not associated with decreases in tricyclic antidepressant use. Throughout follow-up, patients prone to rapid cycling experienced more depressive morbidity than other bipolar patients, particularly when lithium carbonate was being used without tricyclic antidepressants. The use of these antidepressants was not more likely in the weeks preceding shifts from depression to mania or hypomania. CONCLUSIONS: These results indicate that bipolar patients who develop a rapid cycling pattern suffer substantial depressive morbidity and are at high risk for serious suicide attempts. These findings do not implicate tricyclic antidepressants or, by inference, serotonin reuptake inhibitors in the promotion of affective instability.

Adult↗
PubMed2001

Real-time identification of Pseudomonas aeruginosa direct from clinical samples using a rapid extraction method and polymerase chain reaction (PCR).

Pseudomonas aeruginosa has emerged as one of the most problematic Gram-negative nosocomial pathogens. Bacteremia caused by P. aeruginosa is clinically indistinguishable from other Gram-negative infections although the mortality rate is higher. This microorganism is also inherently resistant to common antibiotics. Standard bacterial identification and susceptibility testing is normally a 48-hour process and difficulty sometimes exists in rapidly and accurately identifying antimicrobial resistance. The Polymerase Chain Reaction (PCR) is a rapid and simple process for the amplification of target DNA sequences. However, many sample preparation methods are unsuitable for the clinical laboratory because they are not cost effective, take too long to perform, or do not provide a good template for PCR. Our goal was to provide same-day results to facilitate rapid diagnosis. In this report, we have utilized our rapid DNA extraction method to generate bacterial DNA direct from clinical samples for PCR. The lower detection level for P. aeruginosa was estimated to be 10 CFU/ml. In addition, we wanted to compare the results of a new rapid-cycle DNA thermocycler that uses continuous fluorescence monitoring with the results of standard thermocycling. We tested 40 clinical isolates of P. aeruginosa and 18 non-P. aeruginosa isolates received in a blinded fashion. Coded data revealed that there was 100% correlation in both the rapid-cycle DNA thermocycling and standard thermocycling when compared to standard clinical laboratory results. In addition, total results turn-around time was less than 1 hour. Specific identification of P. aeruginosa was determined using intragenic primer sets for bacterial 16S rRNA and Pseudomonas outer-membrane lipoprotein gene sequences. The total cost of our extraction method and PCR was $2.22 per sample. The accuracy and rapidness of this DNA-extraction method, with its PCR-based identification system, make it an ideal candidate for use in the clinical laboratory.

Bacteremia↗
PubMed1993

Active removal of radioactivity in the blood circulation using biotin-bearing liposomes and avidin for rapid tumour imaging.

In order to shorten the delay between the administration of tumour-imaging agents and obtainment of scintigrams, rapid delivery of radionuclide to tumours followed by rapid clearance from the blood is required. We used liposomes with biotin bound on their surface (B-liposomes) as carriers for rapid delivery. For rapid blood clearance, we employed avidin in the expectation that the strong affinity between biotin and avidin would result in the aggregation of B-liposomes in the blood circulation, and that these aggregates would be taken up rapidly by the reticuloendothelial system, resulting in the rapid elimination of liposomes and the radionuclide encapsulated in them. When B-liposomes encapsulating gallium-67 deferoxamine were intravenously administered to mice bearing sarcoma 180, large amounts of 67Ga were delivered to tumours by 4 h after injection, though the 67Ga blood level remained high. On the other hand, administration of avidin 4 h after administration of the B-liposomes dramatically reduced the blood level so that it was only 5% of that in the non-treated group 1 h later. As a result, the tumour-to-blood ratio reached nearly 14 at 5 h after radionuclide administration, suggesting that rapid tumour-imaging will be feasible by means of this method.

Animals↗
PubMed1979

Longitudinal contraction of isolated guinea-pig ileum induced by rapid cooling.

1. Rapid change of bath temperature from 37 degrees C to 27 degrees C and vice versa caused longitudinal contraction of the isolated guinea-pig ileum. 2. Tetrodotoxin, tropicamide, noradrenaline, isoprenaline, morphine, and the met-enkephalin analogue FK 33-824 depressed the responses or accelerated the fade of the contraction induced by rapid cooling when added after the response had reached its maximum. 3. Hexamethonium had no influence on the responses. 4. Physostigmine potentiated all responses and reversed the fade of contraction induced by rapid cooling when added after this contraction had reached its maximum. 5. The effects of rapid cooling or warming were not altered in preparations made tachyphylactic to substance P; the response to rapid warming, but not cooling, was partially inhibited under tachyphylaxis to 5-hydroxytryptamine. 6. Antazoline, phentolamine, naloxone, and indomethacin did not block the responses. 7. Capsaicin firt potentiated and subsequently depressed the responses to both rapid cooling and warming. 8. The results indicate that rapid change of bath temperature induces longitudinal contraction by excitation of postganglionic cholinergic fibres.

Animals↗
PubMed2001

Diagnosis and treatment of rapidly cycling bipolar disorder.

The conceptualization of rapidly cycling bipolar disorder remains controversial. The DSM-IV definition of rapid cycling, although very reliable, may be not sufficiently inclusive (i.e., it may exclude patients with very short episodes of very high frequency, who are very typical in terms of external validators, and are currently regarded as rapid cyclers by many researchers and clinicians). Moreover, the addition of the requirement of pole switching (i.e., at least one direct transition from one polarity of mood to the other) during the previous year may increase the prognostic and treatment response implications of the diagnosis of rapid cycling. It is commonly held that rapid cyclers are refractory to lithium prophylaxis. However, currently available research evidence suggests that lithium prophylaxis does exert an impact on the course of rapidly cycling bipolar disorder. One double-blind crossover study supports the clinical impression that the combination of at least two mood stabilizers may be needed in most rapid cyclers.

Antimanic Agents↗