Cardiac changes during sleep in sleep-deprived infants

OBJECTIVE: To evaluate the influence of a brief period of sleep deprivation on cardiac autonomic controls during sleep in healthy infants. DESIGN: Twelve healthy infants with a median age of 8 weeks (range, 7 to 18 weeks) were recorded polygraphically during a morning and an afternoon nap in a sleep laboratory. They were sleep deprived for approximately 2 hours, either in the morning or in the afternoon, before being allowed to fall asleep. Six infants were sleep deprived before the morning nap, and 6 before the afternoon nap. During both naps, their sleep, breathing, and heart-rate characteristics were continuously recorded. Spectral analysis of heart rate was evaluated as a function of sleep stages. Two major peaks were recognizable: a low-frequency component related to sympathetic and parasympathetic activities and a high-frequency component reflecting parasympathetic tonus. The ratio of low-frequency to high-frequency powers was calculated as an index of sympathovagal interaction. RESULTS: When sleep deprived, the infants had an increase in basal heart rate during non-rapid eye movement sleep (P=.021). With sleep deprivation, the ratio of low-frequency to high-frequency powers increased in non-rapid eye movement sleep (P=.005). These findings were consistent with an increase in sympathetic tone. CONCLUSION: Infants exposed to short-term sleep deprivation manifest changes in cardiac autonomic controls during sleep. These findings could be relevant to mechanisms associated with the sudden infant death syndrome.     

Reproductive genetic counselling in non-mosaic 47,XXY patients: implications for preimplantation or prenatal diagnosis: Case report and review

With an incidence of approximately 1 in 500 male newborns, the 47,XXY genotype is one the most common sex chromosome anomalies. It is also the most frequent genetic cause of human infertility. Some non-mosaic 47,XXY patients have sperm production which allows infertility treatment to be offered by ICSI. Therefore, the risk of transmitting a chromosome anomaly to the next generation is an important problem in reproductive genetic counselling of these patients. Here, we report on a twin pregnancy where two karyotypically normal neonates 46,XX and 46,XY were born after the use of ICSI in assisted reproduction of a patient with a non-mosaic 47,XXY syndrome. To date, only 38 evolving pregnancies including the present cases, have been reported after ICSI using sperm from non-mosaic 47,XXY patients. Although these data are scarce, they suggest that the risk of chromosome anomaly in the offspring of these patients is low; hence, their reproductive genetic counselling can be reassuring, and management of the pregnancy can proceed with caution.     

Lymphatic endothelial cell identity is reversible and its maintenance requires Prox1 activity

The activity of the homeobox gene Prox1 is necessary and sufficient for venous blood endothelial cells (BECs) to acquire a lymphatic endothelial cell (LEC) fate. We determined that the differentiated LEC phenotype is a plastic, reprogrammable condition that depends on constant Prox1 activity for its maintenance. We show that conditional down-regulation of Prox1 during embryonic, postnatal, or adult stages is sufficient to reprogram LECs into BECs. Consequently, the identity of the mutant lymphatic vessels is also partially reprogrammed as they acquire some features typical of the blood vasculature. siRNA-mediated down-regulation of Prox1 in LECs in culture demonstrates that reprogramming of LECs into BECs is a Prox1-dependent, cell-autonomous process. We propose that Prox1 acts as a binary switch that suppresses BEC identity and promotes and maintains LEC identity; switching off Prox1 activity is sufficient to initiate a reprogramming cascade leading to the dedifferentiation of LECs into BECs. Therefore, LECs are one of the few differentiated cell types that require constant expression of a certain gene to maintain their phenotypic identity.     

High genetic diversity of HIV-1 strains in Chad,West Central Africa

The genetic diversity of HIV-1 strains in Chad was documented with a total of 107 samples from patients attending the general hospital in N'Djamena, the capital city of Chad. The genetic subtypes were identified in the V3-V5 env and p24 gag regions by sequence and phylogenetic tree analyses. Of the 107 strains, 78 had the same subtype/CRF designation between env and gag. Four subtypes and three CRFs were found to cocirculate: subtype A, 20.5%; subtype D, 18.7%; CRF02_AG, 13.1%; CRF11_cpx, 13.1%; subtype G, 3.7%; CRF01_AE, 2.8%; and subtype F1, 0.9%. The remaining 29 strains (27%) had discordant subtypes or CRF designations between env and gag; in 15 of these 29 strains, a CRF was involved in the recombination event, and 10 were subtype G in gag and subtype A in env, forming a separate subcluster within subtypes G and A. Subtype D strains represent almost 20% of the HIV-1 strains circulating in Chad and form a separate subcluster in gag and env. Nearly full-length genome sequencing for two such strains (99TCD-MN011 and 99TCD-MN012) revealed that they represent nonrecombinant subtype D variants. Compared with neighboring countries, the genetic subtype distribution of HIV-1 strains in Chad is unique for several reasons: lower prevalence of CRF02, high prevalence of CRF11 and subtype D, and absence of CRF06. These data clearly show that subtype distribution is very heterogeneous in Africa, probably the result of different founder effects.     

Cortical auditory processing and communication in children with autism: electrophysiological/behavioral relations.

The purpose of the present study was to investigate the relations between late auditory evoked potentials (AEPs) recorded at temporal sites (the N1c wave or Tb) and verbal and non-verbal abilities in children with autism. The study was performed in 26 mentally retarded children with autism (AUT) aged 4-8 years (mean age +/- S.E.M. = 71 +/- 2 months; mean verbal and non-verbal developmental quotient +/- S.E.M. = 36 +/- 4 and 48 +/- 3). The stimuli used were 750 Hz tone bursts of 200 ms duration delivered binaurally at different intensity levels (50, 60, 70, 80 dB SPL) with 3-5 s interstimulus intervals. Temporal AEPs were first compared to those of a group of 16 normal children (NOR) in the same age range (mean age +/- S.E.M. = 69 +/- 3 months). We then focused on the AUT group and considered relations between temporal AEPs and the severity of disorders of verbal and non-verbal communication assessed using a behavior rating scale. AEPs recorded on left and right temporal sites were of smaller amplitude in the AUT group than in the NOR group. Increasing intensity-related amplitude was observed on both sides in NOR and only on the right side in AUT. The lack of intensity effect on the left side resulted in a particular pattern of asymmetry at the highest level of intensity (80 dB SPL) with greater N1c amplitude on the right than on the left side (the reverse was found in the NOR group). Electro-clinical correlations indicated that the greater the amplitude of the right temporal N1c responses, the higher the verbal and non-verbal communication abilities. This suggests a developmental reorganization of left-right hemisphere functions in autism, with preferential activation of the right hemisphere for functions usually allocated to the left hemisphere, particularly those involving the secondary auditory areas situated on the lateral surface of the superior temporal gyrus where the N1c/Tb wave is generated.     

MUC1 expression is correlated with nuclear grade and tumor progression in pT1 renal clear cell carcinoma

We studied, by immunohistochemical analysis, the expression of MUC1 and epithelial membrane antigen in 44 stage pT1 renal cell carcinomas (RCCs). Six patients had a metastatic evolution. The percentage of stained cells was determined for each tumor. All tumors and normal adjacent renal parenchyma were stained. In normal kidney, distal convoluted tubules and collecting ducts stained strongly with an apical distribution. In tumors, there was a significant statistical correlation of the MUC1 expression level with the nuclear grade and with tumor progression. High-grade tumors had more stained cells than did low-grade tumors. Metastatic tumors also were more stained than nonmetastatic lesions. By using the Kaplan-Meier method and the log-rank test, we observed that patients with fewer than 10% of stained cells had no metastatic evolution. In contrast, patients with 70% or more stained cells had significantly lower metastasis-free survival rates. We conclude that MUC1 is expressed in RCC and is associated with tumor progression in pT1 RCC.     

Inter-relationships between pituitary-adrenal hormones and catecholamines during a 6-day Nordic ski race

Summary The aim of the study was to investigate the inter-relationships between pituitary-adrenal hormones and catecholamines during a prolonged competition over 6 days. Plasma adrenocorticotropic hormone (ACTH), cortisol (C), -endorphin (EP), free and sulphated adrenaline (A) and noradrenaline (NA) were measured in 11 volunteer male subjects during a national Nordic-ski race (323 km). Blood samples were obtained before the competition in the evening as control (D₀), and before and after each day's racing (D₁–D₆). The mean daily heart rate (f _c) was calculated fromf _c values recorded every minute during the race. The results showed the following: changes in meanf _c [from 147 (SEM 3) to 156 (SEM 3) beats · min^–1 according to the day] were not significant during the race. Diurnal variations in ACTH, EP and C were no longer apparent after the race: evening levels were higher than their respective D₀ values during the race, except on D₃ when there was a lack of response to exercise in the three hormones. Unlike ACTH and EP, pre- and postexercise C values on D₁ and D₂ were higher than those on the subsequent days (P<0.001). In contrast, there was a progressive accumulation of A and NA in pre-and postrace concentrations which reached a plateau in about 4 days. Positive correlations between exercise responses in ACTH, C and EP were found especially on D₃ and D₆ (P<0.001) but there were no significant correlations between catecholamines and the other three hormones. Thus, prolonged competition over 6 days evoked different control mechanisms for hormones of the pituitary-adrenal axis and catecholamines. A sustained catecholamine release and sympathetic activation induced a progressive NA and A accumulation during the race. In contrast, the lack of a response to exercise in ACTH, EP and C on D₃ suggested a dissociated central command for pituitary axis hormones and sympathetic adrenal activation. On the following days, the response to a lack of exercise, in spite of ACTH stimulation, may have reflected an adaptation of adrenal glands to prolonged stress.     

A locus for Bowen-Conradi syndrome maps to chromosome region 12p13.3

Bowen-Conradi syndrome (BCS) is a lethal autosomal recessive disorder with an estimated incidence of 1 in 355 live births in the Hutterite population. A few cases have been reported in other populations. Here, we report the results of a genome-wide scan and fine mapping of the BCS locus in Hutterite families. By linkage and haplotype analysis the BCS locus was mapped to a 3.5 cM segment (1.9 Mbp) in chromosome region 12p13.3 bounded by F8VWF and D12S397. When genealogical relationships among the families were taken into account in the linkage analysis, the evidence for linkage was stronger and the number of potentially linked regions was reduced to one. Under the assumption that all the Hutterite patients were identical by descent for a disease-causing mutation, haplotype analysis was used to infer likely historical recombinants and thereby narrow the candidate region to a chromosomal segment shared in common by all the affected children. This study also demonstrates that BCS and cerebro-oculo-facial-skeletal syndrome (COFS) are genetically distinct.     

Composite articular cartilage engineered on a chondrocyte-seeded aliphatic polyurethane sponge

To circumvent the reconstructive disadvantages inherent in resorbable polyglycolic acid (PGA)/polylactic acid (PLA) used in cartilage engineering, a nonresorbable, and nonreactive polyurethane sponge (Tecoflex sponge, TS) was studied as both a cell delivery device and as an internal support scaffolding. The in vitro viability and proliferation of porcine articular chondrocytes (PACs) in TS, and the in vivo generation of new articular cartilage and long-term resorption, were examined. The initial cell attachment rate was 40%, and cell density increased more than 5-fold after 12 days of culture in vitro. PAC-loaded TS blocks were implanted into nude mice, became opalescent, and resembled native cartilage at weeks 12 and 24 postimplantation. The mass and volume of newly formed cartilage were not significantly different at week 24 from samples harvested at week 6 or week 12. Safranin O-fast green staining revealed that the specimens from cell-loaded TS groups at week 12 and week 24 consisted of mature cartilage. Collagen typing revealed that type II collagen was present in all groups of tissue-engineered cartilage. In conclusion, the implantation of PAC-TS resulted in composite tissue-engineered articular cartilage with TS as an internal support. Long-term observation (24 weeks) of mass and volume showed no evidence of resorption.