Pathophysiological analysis of serum troponin T release kinetics in evolving ischemic myocardial injury

The present study measured cardiac troponin T(TnT) for the pathophysiological analysis of evolving ischemic myocardial injury in 35 patients with unstable angina (3: Class IB, 32: Class IIIB) and in 40 patients undergoing coronary reperfusion therapy for acute myocardial infarction. Serum TnT, creatine kinase (CK), CKMB, myoglobin (Mb), and myosin light chain 1 (MLC1) were measured every 2-24 h for 10 days after admission to the CCU. In patients with unstable angina, positive test results were detected in 65.7% for TnT, 20% for CK, 37.1% for CKMB, 60.9% for Mb, and 26% for MLC1. Of the 23 patients with positive TnT, 12 (52.2%) had cardiac events. Of the 12 patients with negative TnT, 11 (91.6%) were event-free. All of the patients who developed cardiac events showed a persistent (n = 10) or delayed elevation (n = 2) pattern 28-120 h beforehand. The sensitivity for predicting cardiac events was 92.3% for TnT, 80% for Mb, 53.8% for CKMB, and 50% for MLC1. In patients with acute myocardial infarction, TnT release kinetics showed 2 peaks after coronary reperfusion therapy. TnT values at the 1st peak significantly correlated with maximum CKMB (r = 0.70, p < 0.05) and early-stage left ventricular wall motion score (r = 0.60, p < 0.05), while 2nd-peak TnT values significantly correlated with maximum MLC1 (r = 0.59, p < 0.05), the T1-SPECT score (r = 0.78, p < 0.05) and left ventricular ejection fraction (r = -0.74, p < 0.05) in the convalescent stage. The 2nd/1st-peak TnT ratio significantly correlated with the nQ/nST elevation index (ratio of the number of leads developing abnormal Q-wave 1 week after the onset to the number of leads showing ST elevation of more than 1 mm at admission) (r = 0.63, p < 0.05) in patients with anterior myocardial infarction. These data indicate that persistent release of TnT reflects progressive irreversible myocardial damage in unstable angina and indicates a risk of future cardiac events. In acute myocardial infarction, the 2nd/1st-peak TnT ratio in patients undergoing coronary reperfusion therapy may be useful for the quantitative evaluation of myocardial salvage.

Partial purification and characterization of a novel soybean protease which is inhibited by Kunitz and Bowman-Birk trypsin inhibitors

A novel serine protease has been partially purified from dry seeds of the soybean (Glycine max) cultivar Keburi by cryoprecipitation at pH 6.4, fractional precipitation with ammonium sulfate, and a series of column chromatographic procedures on DEAE-Sepharose, SP-Sepharose, and Arginine-Sepharose 4B. Some properties of the purified enzyme were studied. The protease hydrolyzed the native storage globulins of soybean seeds, such as the alpha subunit of beta-conglycinin, at a pair of arginine residues, Arg126-Arg127. The proteolysis of the alpha subunit in the purified alpha 2 beta molecule of beta-conglycinin apparently followed first order kinetics. The enzyme was inhibited by both soybean Kunitz trypsin inhibitor and Bowman-Birk proteinase inhibitor in a competitive manner. Moreover, the enzyme could catalyze the specific proteolysis of the A3 polypeptide of the purified G5 glycinin at the Arg99-Gly100 linkage, or the carboxyl side of the Arg98-Arg99 paired basic residues.

A mRNA for membrane form of guanylyl cyclase is expressed exclusively in the testis of the sea urchin Hemicentrotus pulcherrimus

A cDNA clone encoding the membrane form of guanylyl cyclase was isolated from a Hemicentrotus pulcherrimus testis cDNA library and its nucleotide sequence was determined. The cDNA was 4123 bp long and an open reading frame predicted a protein of 1125 amino acids including an apparent signal peptide of 21 residues; a single transmembrane domain of 25 amino acids which divides the mature protein into an amino-terminal, extracellular domain of 485 amino acids and a carboxyl-terminal, intracellular domain of 594 amino acids. Three potential N-linked glycosylation sites were present in the extracellular domain. Northern blot analysis of poly(A)+RNA from testes, ovaries, eggs and embryos at various developmental stages showed that the cDNA encoding guanylyl cyclase hybridized to a mRNA of 4.4 kb from the testes. We developed a large scale purification method of the phosphorylated (131 kDa) and dephosphorylated (128 kDa) forms of the membrane-bound guanylyl cyclase from H. pulcherrimus spermatozoa. The purified 131 kDa and 128 kDa forms of the guanylyl cyclase contained 26.0 +/- 1.3 and 4.3 +/- 0.7 moles of phosphate per mol protein (mean +/- S.D.; n = 6), respectively. The amino-terminal amino acids of both the 131 kDa and 128 kDa forms of the guanylyl cyclase could not be detected, suggesting that they were blocked.

Quinolone-resistant mutants of escherichia coli DNA topoisomerase IV parC gene

Escherichia coli quinolone-resistant strains with mutations of the parC gene, which codes for a subunit of topoisomerase IV, were isolated from a quinolone-resistant gyrA mutant of DNA gyrase. Quinolone-resistant parC mutants were also identified among the quinolone-resistant clinical strains. The parC mutants became susceptible to quinolones by introduction of a parC+ plasmid. Introduction of the multicopy plasmids carrying the quinolone-resistant parC mutant gene resulted in an increase in MICs of quinolones for the parC+ and quinolone-resistant gyrA strain. Nucleotide sequences of the quinolone-resistant parC mutant genes were determined, and missense mutations at position Gly-78, Ser-80, or Glu-84, corresponding to those in the quinolone-resistance-determining region of DNA gyrase, were identified. These results indicate that topoisomerase IV is a target of quinolones in E. coli and suggest that the susceptibility of E. coli cells to quinolones is determined by sensitivity of the targets, DNA gyrase and topoisomerase IV.

Food deprivation and hypothermia in desynchronized sleep-deprived rats

Reports of the effect of desynchronized sleep (DS) deprivation on body temperature (Tb) of rats in the literature are contradictory. Since conspicuous body weight loss is common in such deprivation, the effect of food plus DS deprivation on Tb of adult male Wistar rats was studied. DS deprivation carried out by the small platform method with food ad libitum (N = 8) induced hyperthermia (Tb above 38.5 degrees C) in 1 to 3 rats daily until the 8th day, when a case of discrete hypothermia (Tb below 36.9 degrees C) appeared. Food deprivation alone started to induce hypothermia on the third day in one (20%) out of five rats. Fasting imposed from the 5th to the 8th day of DS deprivation (N = 12) caused hypothermia in 33% and 67% of the animals on the second and third day of starvation, respectively. DS compensatory manifestations in 6 starved rats intensified (N = 2) or precipitated (N = 2) hypothermia after the end of sleep deprivation. It is concluded that the hypothermia is not a primary effect of DS deprivation, and this state of sleep seems to have its particular functional role which is independent of thermoregulation.

Extrinsic and intrinsic connections of the cat's lateral suprasylvian visual area

The lateral suprasylvian visual area (LS) is known to have numerous interconnections with visual cortical areas as well as with subcortical structures implicated in visually-guided behaviors. In contrast, little data is available regarding connections within the LS itself. In order to obtain information about intra-areal connections and to re-investigate LS connectivity with various cortical and subcortical areas, the traces (biocytin or WGA-HRP) was injected into various loci along the medial and lateral banks of the LS. The anterograde tracer, biocytin injections into both medial and lateral bank produced label contained within the respective bank that extended rostrally and caudally from the infection site. In addition, following medical bank injections, considerable label was distributed throughout the fundus and, to a lesser extent, in the lateral bank. In contrast, no label could be detected in the medial bank after lateral bank injections, and, although label was observed in the fundus, it was restricted to the most lateral aspects. Moderate labeling could be observed in the medial bank following the tracer injection into the most rostral aspect of the lateral bank. It is likely that input derived from various visual cortical areas which project to the medial bank of the LS has access to this intra-areal circuitry. This may provide a route by which visual cortical information can be relayed to other cortical and subcortical structures involved in visually-guided behaviors such as the anterior ectosylvian visual cortex, striatum, and the deep layers of the superior colliculus, despite the fact that these structures themselves do not receive substantial direct projections from the visual cortical areas that are associated with the medial bank. Examination of the laminar location of the cells-of-origin of striate and extrastriate projections to LS using retrograde trace, WGA-HRP, revealed that the supragranular laminae of areas 17, 18 and 19 were the source of LS afferents whereas afferents from the other cortical areas (e.g., 20a, 20b, 21a, 21b, 7 and anterior ectosylvian visual area) were from both supra- and infragranular laminae. In addition, all LS subregions received intra-areal afferent projections from all LS cortical laminae. Thus, although rather clear hierarchical relationship between LS and visual cortical areas appears to exist, the interconnections among LS subregions provide no clear evidence of simple hierarchical relationships between regions LS or may have feed-forward and feed-back pathways.

Four newly established legal requisites for active euthanasia in Japan

On March 28, 1995 at the Yokohama District Court in Japan, four legal requisites for active euthanasia were newly established by the chief judge, when he rendered the judgment on the murder case of a physician, Tokunaga. The case has been reported by the news media as a so-called euthanasia. In order to make the legal distinction between murder and euthanasia for this case, the 1962 six legal requisites for euthanasia established 33 years ago at the Nagoya High Court in Japan were revised into the four new legal requisites. The judgment was influenced by the current international situation and Japanese sentiment concerning euthanasia.

Chronic rejection in lung allografts: immunohistological analysis of fibrogenesis

In ongoing chronic rejection after lung transplantation, alveolar interstitial fibrosis develops. However, little is known about the mechanisms involved. In order to investigate these mechanisms, expression of extracellular matrix molecules (ECM) (undulin, decorin, tenascin, laminin, and fibronectin) and cytokines [transforming growth factor (TGF)-beta 1, TGF-beta 3, platelet-derived growth factor (PDGF), and PDGF receptor] were semiquantitatively evaluated in chronically rejected lung allografts, using standard immunohistochemical techniques. Additionally, the presence of macrophages was analysed. The present study demonstrates an increased infiltration of macrophages with a concomitant upregulation of cytokines (TGF-beta 1, TGF-beta 3, and PDGF) and an increased deposition of ECM in chronic lung rejection. These cytokines have an important role in the stimulation of fibroblasts which are a major source of ECM. Upregulated expression of ECM in the alveolar interstitial space leads to alveolar malfunction by thickening of the wall and, thus, is one of the causative factors of respiratory dysfunction in chronic lung graft rejection.

Changes in the gonadotropin-releasing hormone pulse generator activity during the estrous cycle in the goat

The hypothalamic GnRH pulse generator activity, which was assessed by the characteristic increases in the multiple unit activity (MUA) specifically associated with the pulsatile LH secretion (MUA volleys), was monitored throughout the estrous cycle of the female goat. Blood samples were collected daily for analysis of progesterone, estradiol and LH levels to monitor ovarian cyclicity. The frequency of the MUA volleys showed a reciprocal relationship with the plasma progesterone profile; being low during the luteal phase, whereas increased during the follicular phase until the onset of the subsequent luteal phase. On the other hand, the duration of the MUA volleys changed in parallel with plasma progesterone levels showing considerable prolongation in the luteal phase. More frequent blood sampling was carried out at 2-hour intervals for timing the LH surge during the follicular phase induced by prostaglandin F2alpha (PGF2alpha) administration. During the PGF2alpha-induced follicular phase, the MUA volley frequency was abruptly increased from 4 h after PGF2alpha injection, and this high frequency was maintained throughout the follicular phase except for the period around the preovulatory LH surge when the MUA volley frequency was lowered temporarily. These results were in accordance with our previous observation that the recurrence of MUA volleys continued with decreased frequency during the estradiol-induced LH surge in ovariectomized goats. The present study revealed that GnRH pulse generator activity changes dramatically during the estrous cycle in the goat, and it is suggested that GnRH pulse generator activity becomes fully potentiated following luteolysis to induce the final follicular development and to stimulate estradiol secretion, which eventually provokes another neural mechanism responsible for the induction of the LH surge.

Natural antibodies against the immunoglobulin F(ab')2 fragment cause elimination of antigens recognized by the F(ab')2 from the circulation

A humanized monoclonal IgG1 antibody, designated hC4G1, recognizes the fibrinogen receptor glycoprotein (GP)IIb/IIIa on platelets and inhibits platelet aggregation. When the F(ab')2 fragment of hC4G1 (F(ab')2 hC4G1) was administered to cynomolgus monkeys, all the monkeys showed inhibition of platelet aggregation ex vivo. Unexpectedly, a significant decrease in platelet count was observed in 5 of 18 monkeys. Antibodies against F(ab')2 hC4G1 were detected in the plasma of these monkeys by ELISA. Antibody activity in the plasma of these monkeys was significantly correlated with the intensity of platelet decrease (r = 0.84). The natural monkey antibodies to F(ab')2 hC4G1 were directed against the C-terminal region of F(ab')2 fragment common to all human and humanized IgG antibodies. Natural homo-reactive antibodies were also detected in human plasma from 15 of 40 healthy volunteers. Specificity was closely similar to that of the monkey antibodies. Affinity-purified human homoreactive antibodies enhanced phagocytosis of platelets treated with the F(ab')2 hC4G1. Monkey plasma with high homo-reactive antibody activity was confirmed to decrease platelet count when administered together with F(ab')2 hC4G1 to a monkey with low antibody activity. These results suggest that F(ab')2 of humanized and human antibodies causes elimination of the corresponding antigens from the circulation by homo-reactive antibodies.

Frequency of a 22q11 deletion in patients with conotruncal cardiac malformations: a prospective study

Recent molecular studies have revealed that a 22q11 deletion is frequently detected in DiGeorge syndrome (DGS), velo-cardio-facial syndrome (VCFS), and conotruncal anomaly face syndrome (CTAFS). As one of the major clinical manifestations in these three syndrome is conotruncal cardiac malformation, we prospectively studied the frequency of a 22q11 deletion in a group of patients with conotruncal cardiac malformation. Fluorescence in situ hybridization (FISH) analyses using N25 (D22S75) DiGeorge Chromosome Region probe were performed on 64 patients with conotruncal cardiac malformation, who visited our clinic from October 1993 to January 1994. Of the 64 patients studied, a 22q11 deletion was detected in 5 patients (7.8%): 3 out of 30 patients with tetralogy of Fallot, one of three with interruption of the aortic arch, and one hemitruncus patient. No deletion was found in 16 patients with complete transposition of the great arteries, 8 with double outlet right ventricle and 2 with aortopulmonary window. In these five patients with 22q11 deletion, patient 1 was clinically diagnosed as having DGS, patients 2 and 3 had CTAFS, and patient 4 had VCFS. Patient 5 could not be dysmorphologically evaluated. It was noteworthy that all patients with a 22q11 deletion, except a non-evaluated patient, had some symptoms DGS, CTAFS or VCFS, and that we failed to identify a non-syndromic 22q11 deletion positive patients in the present series' of 64 patients. Conclusion. This study suggests that it is advisable to bear 22q11 deletion in mind when a patient with conotruncal cardiac anomalies has some other features of DGS, VCFS or CTAFS.

[A case report: complete remission of stage IV uterine cervix carcinoma by immuno-chemotherapy with intraarterial infusion using implantable reservoir system]

A patient with neck lymph node metastasis from squamous carcinoma of the uterine cervix was treated by immunotherapy and neo-adjuvant intraarterial infusion chemotherapy (OK-432 ic, etoposide 25 mg/body x 7 days po, CDDP 100 mg/m2/5 hr iA, CPM 200 mg/body iv, THP 50 mg/m2/2 hr iA). Three courses of the neo-adjuvant chemotherapy were given. After the first course, the neck metastatic tumor appeared remarkably small. After the second, the neck tumor disappeared and the uterine tumor appeared small and to have good movement. Hysterectomy was performed one month after. Each tissue platina concentration (microgram/cm3) is 9.12 uterus cervix, 10.9 uterus corporis, 8.17 fallopian tube, 14.0 ovarium, 1.47-0.88 pelvic lymph node. This patient was treated with irradiation after operation, and is presently in a state of cytological complete remission. Now she continues maintenance immunochemotherapy with UFT and OK-432 with a home doctor.

[Reproducibility of MTD system for detection of Mycobacterium tuberculosis: a cooperative study among six laboratories]

The Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test (MTD) is a rapid test for the detection of Mycobacterium tuberculosis, utilizing the rRNA amplification method. For assessing the reliability and reproducibility of the method, a co-operative blind study was conducted among 6 laboratories. Materials for test were sputum and water samples containing known numbers of Mycobacterium bovis BCG or Mycobacterium avium, and samples without bacteria. From three of 6 laboratories, false-positive results were reported for bacteria negative samples, however, the ratio was below 10%; 8.3% (3/36 samples), 5.6% (2/36), and 2.8% (1/36), respectively. It indicates the indispensability of negative controls for sample pretreatment and RNA extraction stages in the routine MTD test. In every laboratory, all the samples with 10(2) BCG in water and 10(4) BCG in sputum were found to be MTD positive. For the sputum samples with 10(2) BCG, positive results with the ratio above 80% were reported from 4 laboratories. These results indicate that the MTD test based on rRNA amplification method is quite useful for the rapid diagnosis of M. tuberculosis infection.

[Neurological involvements with transient gait disturbance in subacute phase of Kawasaki disease; a case report]

A 1-year-and-9-months old boy with gait disturbance during the 3rd week of Kawasaki disease (KD) was described. He had been previously healthy, and developed high fever and rash. The diagnosis of KD was based on 5 of 6 major criteria on the 3rd clinical day. He was initially treated with intravenous gamma-globulin 400 mg/kg/day for five days. On the 17th clinical day, the patient developed gait disturbance after most clinical signs disappeared. His gait was wide- based and unstable. Generalized hypotonia with poor traction response was also seen. Pyramidal tract signs including exaggerated patellar and Achilles tendon reflexes and positive bilateral Mendel-Bechterew reflex were presented. Cerebrospinal fluid was normal. Brain CT, MRI, and 123I-IMP SPECT images were normal without broad hemorrhage or infarction of the cerebral parenchyma. Gait disturbance recovered spontaneously within one month without any sequelae.

Contribution of the C-8 substituent of DU-6859a, a new potent fluoroquinolone, to its activity against DNA gyrase mutants of Pseudomonas aeruginosa

Inhibitory effects of five quinolones against DNA gyrases purified from four quinolone-resistant clinical isolates of Pseudomonas aeruginosa and the quinolone-susceptible strain PAO1 were examined. All of the quinolone-resistant strains tested were found to be DNA gyrase mutants. The 50% inhibitory concentrations (IC50s) of the quinolones for these DNA gyrases roughly correlated with their MICs. Interestingly, gyrase inhibition by DU-6859a was found to be significantly less affected by these mutations that inhibition by other currently available quinolones. To assess the enhanced activity shown by DU-6859a, the effects of quinolones with altered substituents at the N-1, C-7, and C-8 positions of the quinolone ring of DU-6859a were tested. Measurement of MICs for four DNA gyrase mutants and IC50s for their purified DNA gyrases showed that removal of the C-8 chlorine of DU-6859a significantly increased MICs and IC50s for DNA gyrase mutants. However, no deleterious effects were observed when either the fluorine on the cyclopropyl substituent at the N-1 position or the cyclopropyl ring at the C-7 substituent was removed. Moreover, removal of the C-8 chlorine also increased the MIC for 19 of 20 quinolone-resistant clinical isolates. Our results led to the conclusion that DU-6859a is much more active against quinolone-resistant clinical isolates of P. aeruginosa than other currently available quinolones, probably because of its strong inhibitory effects against mutant quinolone-resistant DNA gyrases, and that the C-8 chlorine is necessary for these potent effects.

[The validity and reliability of a Japanese version of Arthritis Impact Measurement Scales in patients with rheumatoid arthritis]

A Japanese version of Arthritis Impact Measurement Scales (Japanese-AIMS) was developed after the original AIMS Version 2 (AIMS 2). We then conducted a Quality of Life measurement of 691 patients with Rheumatoid Arthritis (RA) with this newly developed questionnaire. Based on the data collected, the validity and reliability of the Japanese-AIMS was examined. The validity of the Japanese-AIMS, which was assessed by the examination of internal consistency among items and through factor analysis, was almost comparable with that of the original AIMS 2. QOL scales were also validated using internal standards based on the subject's responses to other items in the questionnaire. The test-retest reliability, which was the correlation of scale scores between two tests administered 4-5 weeks apart, was slightly lower than the original one. We conclude that the validity and reliability of the Japanese AIMS were comparable with those of the original one, though there could be possibly improved by the minor revision of phrasing. The large scale QOL measurement study with RA patients is under way, using the Japanese-AIMS with minor revision.

[An outbreak of Pontiac fever due to Legionella pneumophila serogroup 7. I. Clinical aspects]

In August 1994, an epidemic of acute febrile illness occurred at the Education Center Building of a company in Shibuya-ku, Tokyo. All 43 trainees attended in two groups and 2 staff members of the Center fell ill. The 45 patients came to one of our hospitals in two groups, and 35 patients were treated. The patients were 4 males and 31 females, and the average age was 29.0 years. The duration until falling ill was 36 to 90 hours after entering the Center. Symptoms were fever, lumbago arthralgia, headache, dyspnea, general fatigue, etc. Physical examination revealed slightly injected mucosa of the pharynx in a patient who complained of a sore throat. On laboratory examination, leukocytosis with a left shift of the nucleus and elevation of serum CRP levels were found. Erythromycin (600 mg, daily) and nonsteroidal antiinflammatory drugs (NSAIDs) were given by mouth to almost every patient. Two patients were hospitalized. The illness was self-limited, generally lasting from two to five days. Strains of legionellae isolated from the water of the cooling tower located at the top of the Center, were identified as L. pneumophila serogroup 7. Since seroconversion in a patient against the cooling tower strain from 1:16 to 1:256 was determined and the clinical courses agreed with the definition of Pontiac fever by Glick et al, we concluded that the epidemic was an outbreak of Pontiac fever due to L. pneumophila serogroup 7. Pontiac fever is considered to be one of the community-acquired diseases. Thus, we have to note that Pontiac fever may be misdiagnosed as we examine patients who complain of the symptoms noted above.

Human herpesvirus-6 infection in renal allografts: retrospective immunohistochemical study in Japanese recipients

This study was conducted to determine the incidence and clinical significance of human herpesvirus-6 (HHV-6) infection in renal allografts. A total of 105 biopsy specimens from 72 recipients were immunohistochemically examined for the presence of HHV-6 antigen, which localized in the distal tubular epithelial cells and in a few lymphocytes infiltrating into the interstitium. HHV-6 antigen in the tubular epithelia was detected in 63 (61.2%) specimens. Categorically, a higher incidence of the antigen was noted in specimens of accelerated rejection (3/4, 75.0%), acute rejection (28/3, 73.7%), and cyclosporin nephropathy (8/11, 72.7%). The antigen was present and absent an almost equal number of times in the categories of chronic rejection, intraoperative and routine protocol biopsies. Repeated biopsies were performed in six cases showing HHV-6 antigen, only one of which underwent transplant nephrectomy due to severe chronic rejection. Single or multinucleated giant cells in distal tubuli occurred in 10 (9.5%) specimens in a scattered manner. All of them were diagnosed as acute or chronic rejection. The giant cells showed no immunoreactivity for HHV-6, cytomegalovirus, or herpes simplex virus. These results indicate overall that HHV-6 infection is common in renal allografts and might be reactivated in acute rejection or cyclosporin nephropathy. The presence of HHV-6 antigen, however, does not necessarily correlate with a poor prognosis for the renal graft nor with the occurrence of giant cells in distal tubuli.

Prophylactic portal infusion chemotherapy as adjuvant therapy for the prevention of metachronous liver metastasis in colorectal cancer

The DNA ploidy and DNA indices (DI) of 414 patients with colorectal cancer were analyzed, and the incidence of patients with metachronous liver metastasis was found to be significantly higher in those with aneuploid tumors and a DI above 1.5 than in those with aneuploid tumors and a DI below 1.4, or in those with diploid tumors and a DI equal to 1.0. Next, to confirm the effectiveness of administering prophylactic portal infusion chemotherapy (PPIC) as adjuvant therapy for the prevention of metachronous liver metastasis in colorectal cancer, a randomized controlled trial of PPIC was performed on 110 consecutive patients with primary colorectal cancer who had undergone curative resection. Although the incidence of patients with metachronous liver metastasis in the two study groups was not significantly different at 3.3% in the PPIC group and 10.3% in the control group, the incidence in the patients with aneuploidy and a DI above 1.5 was significantly lower in the PPIC group than in the control group. These findings suggest that colorectal cancer with aneuploidy and a DI above 1.5 may have a strong tendency to metastasize to the liver, and that prophylactic portal infusion chemotherapy may be effective for preventing metachronous liver metastasis in such patients.

Neocortical spindling during wakefulness in the rat

Neocortical spindling that frequently occurs in rats during wakefulness was studied to evaluate the hypotheses that spindle bursts are either the electrophysiological manifestation of a short-lasting sleep episode that briefly interrupts wakefulness (due to an urge to sleep) or a short decrease of the vigilance level. In order to evaluate sleep need, the latency to the onset of natural sleep, the percentual composition of the sleep-wakefulness cycles, and the durations and intervals of desynchronized sleep episodes were determined in six male Wistar rats weighing 250-350 g and having chronically implanted electrodes for frontal electrocorticogram and cervical electromyogram. These animals were selected on the basis of spindling manifestation during wakefulness. The occurrence of spindling during a period of repeated painful tail-pinching was subsequently measured to determine the vigilance level in the same animals. Two rats were also studied during forced immobilization for the same purpose. Sleep parameters were found to be normal in all rats studied, thus excluding the hypothesis that spindling in wakefulness is a manifestation of a high sleep need. Spindling also occurred in both situations requiring a high level of vigilance (frequent tail-pinching and forced immobilization). Natural sleep cycles never started with this type of spindling, which is not related to the typical synchronization patterns of synchronized sleep. The frequency of the potentials that make up spindles in wakefulness were systematically 1 to 2 Hz lower than those of synchronized sleep in all animals studied. The possibility that spindling during wakefulness may be associated to brief episodes of distraction is discussed.