Alpha activity and cardiac correlates: three types of relationships during nocturnal sleep

OBJECTIVE

We examined simultaneously alpha activity and cardiac changes during nocturnal sleep, in order to differentiate non-rapid eye movement (NREM) sleep, REM sleep, and intra-sleep awakening.

METHODS

Ten male subjects displaying occasionally spontaneous intra-sleep awakenings underwent EEG and cardiac recordings during one experimental night. The heart rate and heart rate variability were calculated over 5 min periods. Heart rate variability was estimated: (1) by the ratio of low frequency (LF) to high frequency (HF) power calculated from spectral analysis of R-R intervals; and (2) by the interbeat autocorrelation coefficient of R-R intervals (rRR). EEG spectral analysis was performed using a fast Fourier transform algorithm.

RESULTS

Three types of relationships between alpha waves (8-13 Hz) and cardiac correlates could be distinguished. During NREM sleep, alpha activity and cardiac correlates showed opposite variations, with high levels of alpha power associated with decreased heart rate, rRR and LF/HF ratio, indicating low sympathetic activity. Conversely, during REM sleep, alpha activity was low whereas heart rate, rRR, and the LF/HF ratio peaked, indicating high sympathetic activity. During intra-sleep awakenings, alpha activity and cardiac correlates both increased. No difference in time-course between alpha 1 (8-10 Hz) and alpha 2 (10-13 Hz) activity could be shown. Alpha waves occurred in fronto-central areas during slow wave sleep (SWS), migrated to posterior areas during REM sleep, and were localized in occipital areas during intra-sleep awakenings.

CONCLUSIONS

These results suggest that alpha waves are not simply a sign of arousal, as is commonly thought. Fronto-central alpha waves, associated with decreased heart rate, possibly reflect sleep-maintaining processes.

The performance of several multiple-sequence alignment programs in relation to secondary-structure features for an rRNA sequence

The performances of five global multiple-sequence alignment programs (CLUSTAL W, Divide and Conquer, Malign, PileUp, and TreeAlign) were evaluated using part of the animal mitochondrial small subunit (12S) rRNA molecule. Conserved sequence motifs derived from an alignment based on secondary structural information were used to score how well each program aligned a data set of five vertebrate and five invertebrate taxa over a range of parameter values. All of the programs could align the motifs with reasonable accuracy for at least one set of parameter conditions, although if the whole sequence was considered, similarity to the structural alignment was only 25%-34%. Use of small gap costs generally gave more accurate results, although Malign and TreeAlign generated longer alignments when gap costs were low. The programs differed in the consistency of the alignments when gap cost was varied; CLUSTAL W, Divide and Conquer, and TreeAlign were the most accurate and robust, while PileUp performed poorly as gap cost values increased, and the accuracy of Malign fluctuated. Default settings for the programs did not give the best results, and attempting to select similar parameter values in different programs did not always result in more similar alignments. Poor alignment of even well-conserved motifs can occur if these are near sites with insertions or deletions. Since there is no a priori way to determine gap costs and because such costs can vary over the gene, alignment of rRNA sequences, particularly the less well conserved regions, should be treated carefully and aided by secondary structure and conserved motifs. Some motifs are single bases and so are often invisible to alignment programs. Our tests involved the most conserved regions of the 12S rRNA gene, and alignment of less well conserved regions will be more problematical. None of the alignments we examined produced a fully resolved phylogeny for the data set, indicating that this portion of 12S rRNA is insufficient for resolution of distant evolutionary relationships.

Pharmacologic characteristics of indinavir, didanosine, and stavudine in human immunodeficiency virus-infected children receiving combination therapy

The use of human immunodeficiency virus (HIV) protease inhibitors in children has lagged behind that in adults because of the lack of suitable pediatric formulations and information on safe and effective dosing regimens. This study was designed to obtain pharmacokinetic information on indinavir, administered to HIV-infected children also receiving therapy with two nucleoside agents, and to explore relationships between pharmacokinetic parameters and anti-HIV effect. Indinavir was initiated at a dose of 500 mg/m(2) every 8 h. Plasma indinavir concentrations were measured every 4 weeks; the dose or dosing interval was adjusted to maintain trough concentrations of > or =0.1 mg/liter. All children were evaluated clinically at baseline and every 4 weeks. Plasma HIV RNA was quantitated at baseline and at weeks 4, 12, and 24. Eighteen children participated in this study. The average daily dose of indinavir was 2,043 mg/m(2); nine children received indinavir at 6-h intervals. Pharmacokinetic characteristics of indinavir (mean +/- standard deviation) were the following: oral clearance, 1.4 +/- 0.5 liters/h/kg; half-life, 1.1 +/- 0.43 h; and trough concentration, 0. 29 +/- 0.32 mg/liter. In nine children that completed 24 weeks of therapy, the baseline-to-week-24 change in HIV RNA level was related to indinavir trough concentration and didanosine area under the curve. This study illustrates the ability to obtain pharmacokinetic information from children during routine clinic visits and to use this information to provide a safeguard against underdosing. The incorporation of pharmacologic knowledge with virologic, immunologic, and behavioral considerations should result in improved clinical outcomes for children infected with HIV.

Optimal quantum cloning via stimulated emission

We show that optimal universal quantum cloning can be realized via stimulated emission. Universality of the cloning procedure is achieved by choosing systems that have appropriate symmetries. We first discuss a scheme based on stimulated emission in certain three-level systems, e.g., atoms in a cavity. Then we present a way of realizing optimal universal cloning based on stimulated parametric down-conversion. This scheme also implements the optimal universal NOT operation.

Twenty-four-hour rhythms of plasma glucose and insulin secretion rate in regular night workers

To determine whether the ultradian and circadian rhythms of glucose and insulin secretion rate (ISR) are adapted to their permanent nocturnal schedule, eight night workers were studied during their usual 24-h cycle with continuous enteral nutrition and a 10-min blood sampling procedure and were compared with 8 day-active subjects studied once with nocturnal sleep and once with an acute 8-h-shifted sleep. The mean 24-h glucose and ISR levels were similar in the three experiments. The duration and the number of the ultradian oscillations were influenced neither by the time of day nor by the sleep condition or its shift, but their mean amplitude increased during sleep whenever it occurred. In day-active subjects, glucose and ISR levels were high during nighttime sleep and then decreased to a minimum in the afternoon. After the acute sleep shift, the glucose and ISR rhythms were split in a biphasic pattern with a slight increase during the night of deprivation and another during daytime sleep. In night workers, the glucose and ISR peak levels exhibited an 8-h shift in accordance with the sleep shift, but the onset of the glucose rise underwent a shift of only 6 h and the sleep-related amplification of the glucose and ISR oscillations did not occur simultaneously. These results demonstrate that despite a predominant influence of sleep, the 24-h glucose and ISR rhythms are only partially adapted in permanent night workers.

Oral manifestations of pediatric vertical HIV infection

To assess the prevalence and prognostic significance of the history of oral manifestations in children with human immunodeficiency virus infection (HIV), a cohort study of 73 children with vertical HIV infection was conducted. The study subjects were examined every 6 months for oral manifestations. The period prevalence of oral manifestations ranged from a low of 1% for submandibular enlargement and 3% for hairy leukoplakia to a high of 36% for xerostomia and 51% for cervical lymphadenopathy. The occurrence of oral manifestations did not change significantly over time from 1995 to 1998. Finally, the odds of occurrence of cervical lymphadenopathy, xerostomia, and oral candidiasis were greater among children in whom these manifestations had been diagnosed in the preceding 6-18 months than in children without prior diagnosis. Oral manifestations are significant clinical outcomes in pediatric vertical HIV infection, particularly for children diagnosed previously with an oral manifestation.

Upregulation of hepatic glucose 6-phosphatase gene expression in rats treated with an inhibitor of glucose-6-phosphate translocase

The multicomponent hepatic glucose 6-phosphatase (Glc-6-Pase) system catalyzes the terminal step of hepatic glucose production and plays a key role in the regulation of blood glucose. We used the chlorogenic acid derivative S 3483, a reversible inhibitor of the glucose-6-phosphate (Glc-6-P) translocase component, to demonstrate for the first time upregulation of Glc-6-Pase expression in rat liver in vivo after inhibition of Glc-6-P translocase. In accordance with its mode of action, S 3483-treatment of overnight-fasted rats induced hypoglycemia and increased blood lactate, hepatic Glc-6-P, and glycogen. The metabolic changes were accompanied by rapid and marked increases in Glc-6-Pase mRNA (above 35-fold), protein (about 2-fold), and enzymatic activity (about 2-fold). Maximal mRNA levels were reached after 4 h of treatment. Glycemia, blood lactate, and Glc-6-Pase mRNA levels returned to control values, whereas Glc-6-P and glycogen levels decreased but were still elevated 2 h after S 3483 withdrawal. The capacity for Glc-6-P influx was only marginally increased after 8.5 h of treatment. Prevention of hypoglycemia by euglycemic clamp did not abolish the increase in Glc-6-Pase mRNA induced by S 3483 treatment. A similar pattern of hypoglycemia and possibly of associated counterregulatory responses elicited by treatment with the phosphoenolpyruvate carboxykinase inhibitor 3-mercaptopicolinic acid could account for only a 2-fold induction of Glc-6-Pase mRNA. These findings suggest that the significant upregulation of Glc-6-Pase gene expression observed after treatment of rats in vivo with an inhibitor of Glc-6-P translocase is caused predominantly either by S 3483 per se or by the compound-induced changes of intracellular carbohydrate metabolism.

May-Thurner syndrome in an adolescent: persistence despite operative management

We describe a patient with May-Thurner syndrome who underwent operative transection and transposition of the right common iliac artery without direct venous repair, because preoperative and intraoperative intravascular ultrasound scans were negative for "spurs" in the left common iliac vein. When symptoms and signs persisted, a postoperative magnetic resonance venogram (MRV) showed severe stenosis in the left common iliac vein. Progressive, but incomplete, clinical improvement occurred with conservative management.

[Minor functional disorders after surgery of acoustic nerve neuroma]

Acoustic neuromas must be removed surgically, otherwise serious complications may occur. Removal of an acoustic neuroma most often leads to disorders of balance, hearing, and sometimes facial motor function. Many earlier studies have approached the hearing and facial motor function. However, the facial nerve also comprises sensory and secretory fibers which, when injured, may produce minor disorders affecting patient's quality of life. The purpose of this work was to evaluate the quality of life, secretory and taste disorders after acoustic neuroma surgery.

PATIENTS AND METHOD

Among patients operated on between May 1985 and May 1996, we selected only those who presented a normal facial function 3 months after surgery. We thus selected 93 patients and sent them a questionnaire in December 1997. We received 74 answers.

RESULTS

The period between the operation and the dispatch of the questionnaire was on an average 5.5 years (range 19 months-12 years 9 months). Impairment of quality of life was frequent (59% of cases), and changing way of life less so (30%). 74% of the patients described balance disorders. One-quarter of the patients indicated they experienced disorders of facial mobility. Only 3 patients had no disorder.

CONCLUSION

Secretory and taste disorders are frequent after neuroma surgery. Despite their mildness, patients should be advised accordingly because of possible impact on quality of life. This study also points out the lack of precision in the estimation of facial mobility. A better evaluation of patient complaints would be useful.

Does parental breastfeeding knowledge increase breastfeeding rates?

OBJECTIVE

Although improving mothers' knowledge about breastfeeding can increase rates and duration of breastfeeding, little is known about the influence of fathers' knowledge. The purpose of this study was to assess the knowledge of mothers and fathers about breastfeeding before and after receiving postpartum advice and its relationship to the frequency of breastfeeding.

METHODS

A clinical trial was performed with mothers and fathers of normal children born at the Hospital de Clínicas de Porto Alegre, Brazil, between July 1994 and March 1995. The study intervention consisted of postpartum advice supplied by means of a video film discussing basic topics of breastfeeding, an explanatory leaflet, and open discussion after viewing the video. The first 208 couples comprised the control group, the next 197 comprised experimental group 1, and the remaining 196 comprised experimental group 2. Immediately after delivery, mothers and fathers in the three groups answered a test on breastfeeding knowledge; they completed the same test at the end of the first month. All families received home visits at the end of the first, second, fourth, and sixth months, or until breastfeeding ceased. Logistic regression was used to evaluate the association between the mothers' and fathers' knowledge and frequency of breastfeeding.

RESULTS

Postpartum advice increased the breastfeeding knowledge of mothers and fathers. The mothers with the highest level of knowledge had a 6.5 times higher chance of exclusively breastfeeding at the end of the third month, and 1.97 times higher chance of continuing breastfeeding to the end of the sixth month compared with other mothers. The fathers' knowledge also significantly influenced breastfeeding rates. The children whose fathers knew more had a 1.76 higher chance of being exclusively breastfed at the end of the first month, and 1.91 higher chance of receiving maternal milk at the end of the third month.

CONCLUSION

A simple, inexpensive strategy can increase the level of breastfeeding knowledge of mothers and fathers and, consequently, have a positive impact on the frequency of breastfeeding.

Neuroendocrine processes underlying ultradian sleep regulation in man

Sleep is not a uniform state but is characterized by the cyclic alternation between rapid eye movement (REM) and non-REM sleep with a periodicity of 90-110 min. This cycle length corresponds to one of the oscillations in electroencephalographic (EEG) activity in the delta frequency band (0.5-3.5 Hz), which reflect the depth of sleep. To demonstrate the intimate link between EEG and neuroendocrine rhythmic activities in man, we adopted a procedure permitting simultaneous analysis of sleep EEG activity in the delta band and of two activating systems: the adrenocorticotropic system and the autonomic nervous system. Adrenocorticotropic activity was evaluated by calculating the cortisol secretory rate in blood samples taken at 10-min intervals. Autonomic activity was estimated by two measures of heart rate variability: 1) by the ratio of low-frequency (LF) to high-frequency (HF) power from spectral analysis of R-R intervals; and 2) by the interbeat autocorrelation coefficient of R-R intervals (rRR intervals between two successive cardiac beats). The results revealed that oscillations in delta wave activity, adrenocorticotropic activity, and autonomic activity are linked in a well-defined manner. Delta wave activity developed when cortisol secretory rates had returned to low levels and sympathetic tone was low or decreasing, as reflected by a low LF/HF ratio and by low levels in rRR. Conversely, the decrease in delta wave activity occurred together with an increase in the LF/HF ratio and in rRR. REM sleep was associated with a decrease in cortisol secretory rates preceding REM sleep onset, whereas the LF/HF ratio and rRR remained high. These results demonstrate a close coupling of adrenocorticotropic, autonomic, and EEG ultradian rhythms during sleep in man. They suggest that low neuroendocrine activity is a prerequisite for the increase in slow wave activity.

PD 098059, an inhibitor of ERK1 activation, attenuates the in vivo invasiveness of head and neck squamous cell carcinoma

Increased mortality of patients with oral cancer largely reflects the local and regional spread of the disease. The invasiveness of these tumours requires hydrolases which are regulated through AP-1-dependent transcriptional mechanisms. Since the amount/activity of transcription factors bound to the AP-1 motif are regulated partly through the extracellular signal-regulated kinases (ERK1/ERK2), we determined the effect of PD 098059, an inhibitor of ERK1/ERK2 activation, on the in vivo invasiveness of a human squamous cell carcinoma cell line (UM-SCC-1) derived from the oral cavity. We utilized the floor of mouth musculature consisting of the mylohyoid, geniohyoid and genioglossus muscle (which are sequentially arranged), as a natural barrier to assess tumour spread in vivo in the nude mouse. Mice were inoculated with tumour cells superficial to the mylohyoid muscle. After 18 days, tumours were injected with either empty liposomes (control) or liposomes containing 5 microM PD 098059 and, after an additional 22 days, the jaws of mice examined histologically. Highly infiltrative tumours, which had penetrated the genioglossus muscle, were evident in 10/12 control mice. In contrast, in 9/12 mice in which the tumours were injected with PD 098059, tumours did not extend beyond the mylohyoid or geniohyoid muscles. Tumours penetrated bone nutrient canals in 7/12 control mice but in only 3/12 PD 098059-treated mice. Neurotropism, characteristic of aggressive oral squamous cell carcinoma, was evident in 6/12 control mice but was completely abolished (0/12 mice) in the PD 098059-treated mice. Using a staging system based on the muscle layer involved, neurotropism, as well as bone involvement, we found the inhibition of invasion to be statistically significant (P < 0.01). The reduced invasiveness of the PD 098059-liposome-treated oral cancers was associated with diminished 92-kDa type IV collagenase and ERK1/ERK2 activities but was not a consequence of a slower tumour growth rate. This is the first study to demonstrate reduced in vivo invasiveness of a malignancy brought about by an inhibitor of ERK1/ERK2 activation. These results raise the exciting possibility that second generation PD 098059 congeners may reduce the spread of the disease in patients afflicted with oral cancers.

Adult pseudosarcoma of the bladder

Pseudosarcomatous tumor of the urinary bladder is an unusual benign proliferative lesion that poses a diagnostic dilemma for both the urologist and pathologist. Its clinical and histologic features mimic a malignant neoplasm, although simple excision is curative. Although similar lesions have been reported in multiple extravesicle locations, most commonly the lung, bladder lesions have only recently been reported. We describe 2 cases of pseudosarcomatous bladder tumors presenting in patients with no known risk factors. We review clinical, histologic, and management issues in these patients. By recognizing the existence of this lesion, possible extensive and inappropriate surgery may be avoided.

A program of acquired immune deficiency syndrome education for nurses in Romania

After the fall of the communist government in Romania, many children were found to be human immunodeficiency virus (HIV) infected. The majority of these children were abandoned and currently live in orphanages. The children have been cared for on a day-to-day basis by nurses with little general nursing education and even less HIV education. The Romanian-American Pediatric AIDS Education and Clinical Research Program was established at Texas Children's Hospital and Baylor College of Medicine in May, 1996 to aid in the education of Romanian nurses. Syllabi developed by the U.S. nursing team were initially piloted in three pediatric HIV centers in Romania in July, 1997. Since that time, two annual nursing symposia have been held offering topics on general pediatrics and HIV-related content. The purpose of this article is to describe a program of HIV education for nurses in Romania.

mtDNA analysis of Nile River Valley populations: A genetic corridor or a barrier to migration?

To assess the extent to which the Nile River Valley has been a corridor for human migrations between Egypt and sub-Saharan Africa, we analyzed mtDNA variation in 224 individuals from various locations along the river. Sequences of the first hypervariable segment (HV1) of the mtDNA control region and a polymorphic HpaI site at position 3592 allowed us to designate each mtDNA as being of "northern" or "southern" affiliation. Proportions of northern and southern mtDNA differed significantly between Egypt, Nubia, and the southern Sudan. At slowly evolving sites within HV1, northern-mtDNA diversity was highest in Egypt and lowest in the southern Sudan, and southern-mtDNA diversity was highest in the southern Sudan and lowest in Egypt, indicating that migrations had occurred bidirectionally along the Nile River Valley. Egypt and Nubia have low and similar amounts of divergence for both mtDNA types, which is consistent with historical evidence for long-term interactions between Egypt and Nubia. Spatial autocorrelation analysis demonstrates a smooth gradient of decreasing genetic similarity of mtDNA types as geographic distance between sampling localities increases, strongly suggesting gene flow along the Nile, with no evident barriers. We conclude that these migrations probably occurred within the past few hundred to few thousand years and that the migration from north to south was either earlier or lesser in the extent of gene flow than the migration from south to north.

[Bone anchored hearing aid (BAHA): clinical evaluation]

The bone-anchored hearing aid (BAHA) allows direct bone-conduction through a titanium implant. This avoids skin irritation and seems to improve the sound quality when compared with a conventional bone hearing aid. Aim of this work was to evaluate this new hearing-aid.

PATIENTS AND METHODS

9 patients have been operated on between May 1994 and April 1997. Two aural atresia and 7 radical mastoidectomy; 6 had prior conventional bone hearing aid and one a bilateral air-conduction hearing aid. Their mean bone conduction threshold was 28 dB (17-38 dB). Their maximum speech discrimination score was 100%. Audiological tests and questionnaires were used for the evaluation.

RESULTS

The mean follow-up was 9-months (3-35). Osseointegration succeeded in the 9 cases. Skin tolerance was excellent in 6 cases. 3 patients had transient adverse skin reactions, with one having needed a revision surgery under local anesthesia. All patients use their BAHA everyday. The mean prosthesis gain was 36 dB (20-50 dB). Eight patients completed the questionnaire. Patients reported an overall satisfaction score between 9 and 10 (range 6-10). BAHA advantageously replaced the prior hearing aid (mean satisfaction score: 9.1 for BAHA versus 5.9). The only complaints were sensitivity to wind noise and lack of a phone connexion.

Influence of alcohol consumption and various beverages on waist girth and waist-to-hip ratio in a sample of French men and women

OBJECTIVE

The goal of the present study was to assess the association between alcohol consumption and abdominal fat deposition in France, a country where wine is the most commonly consumed alcoholic beverage.

METHODS

We analyzed the association between alcohol consumption and various markers of body weight, in a population sample recruited in three distinct geographical areas of France (MONICA centers). This sample included men (n = 1778) and women (n = 1730) aged 35- 64 y, randomly selected from electoral rolls. Alcohol consumption was assessed with a quantitative frequency questionnaire.

RESULTS

Alcohol intake ranged from 0-1655 ml of alcohol per week. Wine was the main source of alcohol, representing 67% of total alcohol intake in both genders. In men, there was no association between alcohol intake and body mass index (BMI) or body weight, whereas in women, alcohol consumption was inversely correlated with BMI (P < 0.0001) and body weight (P < 0.0002). In men, total alcohol consumption was positively associated with waist-to-hip ratio (WHR, P < 0.0002) and waist girth (P < 0.004), independently of BMI. Similarly, in women, positive associations were found between alcohol intake and WHR (P < 0.0001) as well as waist girth (P < 0.0001), independently of BMI. In a linear regression model including types of beverages and usual confounders, reporting consumption of either wine, beer or spirit was poorly associated with WHR in men, whereas wine (P < 0.0008) and beer (P < 0.0001) consumptions were both positively associated with WHR in women. However, there was no evidence of a statistically significant heterogeneous effect of wine, beer and spirits on WHR in both genders.

CONCLUSION

In a sample of representative French people, in whom wine is the most common alcoholic beverage, alcohol consumption is associated with greater WHR independently of BMI in both men and women.

An orthotopic floor-of-mouth cancer model allows quantification of tumor invasion

OBJECTIVES

To establish an orthotopic murine floor-of-mouth cancer model for the analysis of the role of proteases such as urokinase-type plasminogen activator (u-PA) and the matrix metalloprotease MMP-9 (MMP-9) in in vivo invasion.

STUDY DESIGN

Randomized, prospective animal study.

METHODS

Two human squamous cell carcinoma cell lines, UM-SCC-1 and 022, were assayed via zymography for their in vitro secretion levels of u-PA and MMP-9. Both cell lines (5 x 10(6) cells) were injected into the cervical subcutaneous tissues of female athymic nude (nu/nu) mice superficial to the mylohyoid muscle. Mice were sacrificed after 30 days, and tumor invasion characteristics were histologically compared. Additional mice were then inoculated with invasive UM-SCC-1 cells and sacrificed 10, 30, and 40 days after inoculation to identify distinct stages of invasion.

RESULTS

In vitro secretion levels of MMP-9 and activity of u-PA were higher in UM-SCC-1 cells than in 022 cells. In the in vivo studies, tumors formed from 022 cells were found to be noninvasive, whereas tumors derived from UM-SCC-1 cells progressed through distinct and readily identifiable histologic stages of invasion. These stages included invasion of adjacent muscle layers (mylohyoid, geniohyoid, and genioglossus muscles) and of associated structures (blood vessels, bone, nerve, and regional lymph nodes). A staging system was devised accordingly.

CONCLUSION

We developed an in vivo quantitative cancer invasion model that allows determination of the effect of the expression and activity levels of the proteases MMP-9 and u-PA. Tumor invasion occurred in an orderly and stepwise fashion involving muscles and related vascular, nervous, and bony structures of the floor of the mouth and tongue. This orderly invasion allowed the development of a staging system. We anticipate that this model will have wide applicability in the study of in vivo tumor response to a variety of novel therapeutic approaches.

Dynamic heart rate variability: a tool for exploring sympathovagal balance continuously during sleep in men

We have recently demonstrated that the overnight profiles of cardiac interbeat autocorrelation coefficient of R-R intervals (rRR) calculated at 1-min intervals are related to the changes in sleep electroencephalographic (EEG) mean frequency, which reflect depth of sleep. Other quantitative measures of the Poincaré plots, i.e., the standard deviation of normal R-R intervals (SDNN) and the root mean square difference among successive R-R normal intervals (RMSSD), are commonly used to evaluate heart rate variability. The present study was designed to compare the nocturnal profiles of rRR, SDNN, and RMSSD with the R-R spectral power components: high-frequency (HF) power, reflecting parasympathetic activity; low-frequency (LF) power, reflecting a predominance of sympathetic activity with a parasympathetic component; and the LF-to-HF ratio (LF/HF), regarded as an index of sympathovagal balance. rRR, SDNN, RMSSD, and the spectral power components were calculated every 5 min during sleep in 15 healthy subjects. The overnight profiles of rRR and LF/HF showed coordinate variations with highly significant correlation coefficients (P < 0.001 in all subjects). SDNN correlated with LF power (P < 0.001), and RMSSD correlated with HF power (P < 0.001). The overnight profiles of rRR and EEG mean frequency were found to be closely related with highly cross-correlated coefficients (P < 0. 001). SDNN and EEG mean frequency were also highly cross correlated (P < 0.001 in all subjects but 1). No systematic relationship was found between RMSSD and EEG mean frequency. In conclusion, rRR appears to be a new tool for evaluating the dynamic beat-to-beat interval behavior and the sympathovagal balance continuously during sleep. This nonlinear method may provide new insight into autonomic disorders.

Isolation of Lautropia mirabilis from oral cavities of human immunodeficiency virus-infected children

Lautropia mirabilis, a pleomorphic, motile, gram-negative coccus, has been isolated from the oral cavities of 32 of 60 (53.3%) children infected with human immunodeficiency virus (HIV) and 3 of 25 (12.0%) HIV-uninfected controls; the association of L. mirabilis isolation with HIV infection is significant (P < 0.001). All children in the study, both HIV-infected children and controls, were born to HIV-infected mothers. The presence of this bacterium was not associated with clinical disease in these children. The HIV-infected children with L. mirabilis did not differ from the HIV-infected children without L. mirabilis in immunological status, clinical status, or systemic medications. The role of HIV infection itself or concomitant factors in the establishment of L. mirabilis in the oral cavity remains to be elucidated.