Carcinoma in situ testis displays permissive chromatin modifications similar to immature foetal germ cells.

BACKGROUND: The majority of testicular germ cell cancers develop through a pre-invasive carcinoma in situ (CIS) stage. The CIS cell is a neoplastic counterpart of foetal germ cells. During their development, foetal germ cells undergo extensive and essential epigenetic modifications, but little is known about epigenetic patterns in CIS cells. METHODS: Immunohistochemistry was used to investigate epigenetic patterns in CIS, germ cell tumours, normal adult and foetal testicular tissue. RESULTS: CIS cells show low levels of DNA methylation and repressive histone modifications H3K9me2 and H3K27me3, but high levels of H3K9 acetylation, H3K4 methylation and H2A.Z, which all are associated with an activated and accessible chromatin structure. Collectively this renders a permissive chromatin structure and in accordance high levels of RNA polymerase II activity and proliferation (Ki-67 and mitotic index) is observed in CIS cells. Epigenetic patterns similar to that of CIS cells were observed in human gonocytes present within sex cords in foetal testes but correspond to migrating primordial germ cell in mice. Development of overt tumours involves epigenetic repression of the chromatin. CONCLUSION: CIS cells have a permissive and foetal-like chromatin structure, which is associated with a high transcriptional and proliferative activity, likely empowering neoplastic transformation. Developmental epigenetic cues in foetal germ cells are substantially different between humans and mice.

Obstacles to discharge of ventilator-assisted children from the hospital to home.

Home care for ventilatory-assisted children improves psychosocial development and reduces medical costs compared with hospital care; yet, many ventilator-assisted children remain hospitalized for lengthy periods of time after they have achieved medical stability. To identify factors that contributed to a delay in hospital discharge from the time medical stability was achieved, we reviewed the records of 54 ventilator-assisted children (age 4.6 +/- 5.9 [SD] years at discharge) who were discharged from the hospital on a regimen of home mechanical ventilation. The length of the hospitalization from which the ventilator-assisted children were initially discharged on the ventilator was 172 +/- 161 days (range, 2 to 756). The time from medical stability to discharge was 118 +/- 144 days (range, 2 to 724), or 73 percent +/- 29 percent of the total hospitalization. Fifty-one ventilator-assisted children were discharged to their natural parents' homes, and three were discharged to foster care. Once ventilator-assisted children were medically stable, it took 99 +/- 141 days for third-party payers to approve home care funding, and only 48 +/- 87 days to be discharged once funding was approved. For the 27 ventilator-assisted children with public funding, it took 184 +/- 177 days for home care funding approval, compared with 52 +/- 43 days for the 27 ventilator-assisted children with private funding (p < 0.001). Parent training took only 52 +/- 65 days. It took 369 +/- 334 days (range, 44 to 711 days) to find placement for the three ventilator-assisted children who were placed in medical foster care. In summary, ventilator-assisted children often remained hospitalized for prolonged periods of time, after they were medically stable, for nonmedical reasons. The greatest obstacle to hospital discharge was seeking approval for home care funding and for arranging out-of-home placement. Public funding agencies took significantly longer to approve home care funding than private insurance agencies.

Frequency, causes, and outcome of home ventilator failure.

STUDY OBJECTIVES: The safety of home ventilators has been questioned. We collected data to study the following: frequency of home ventilator failure, apparent causes for the failure or malfunction, and adverse consequences following the failure. STUDY DESIGN: Information on all requests to correct home ventilator failures reported to a home respiratory equipment vendor was collected prospectively between November 1991, and November 1992. PATIENTS: There were 150 ventilator-assisted patients aged 2 to 77 years; 44 were < or = 18 years. They received 841,234 h of home mechanical ventilation (average, 15.4 h/d per ventilator-assisted patient). RESULTS: There were 189 reports of home ventilator failure. Defective equipment or mechanical failure was found in only 39% (73 reports), equivalent to one home ventilator failure for every 1.25 years of continuous use. Other causes of ventilator failure included the following: improper care, damage, or tampering with the ventilator by caregivers (13%), functional equipment improperly used by caregivers (30%), and equipment functional but the patient's condition changed, mimicking ventilator failure (3%). No problem could be identified in 16%. The following actions were required: ventilator replacement (44%), repair of a defective part (6%), replacement of a functioning ventilator for psychological comfort (14%), ventilator adjustments made (21%), caregiver reeducation (7%), caregiver anxiety or distress reduced (3%), and no action required (4%). Hospitalization was required only in two cases (1%). No adverse outcomes, deaths, or serious injuries were associated with home ventilator failure. CONCLUSIONS: We conclude that in 150 patients requiring home mechanical ventilation, ventilator failure occurred relatively infrequently, and there were no adverse outcomes as a result of equipment failure at home. We speculate that equipment failure is not a frequent or serious problem for ventilator-assisted patients treated at home.

Spermatogonial multiplication in the Chinese hamster. IV. Search for long cycling stem cells.

In the Chinese hamster, 17 days, i.e. one cycle of the seminiferous epithelium, after two injections of [3H]TdR given 24 hr apart, labelled cells were found among all types of spermatogonia, including stem cells (As). These labelled As spermatogonia derive from one or more self-renewing divisions of the stem cells that originally incorporated [3H]TdR. In the steady state, half of the divisions of the As will be self-renewing and the other half will give rise to Apr spermatogonia that will ultimately become spermatozoa. Theoretically, the labelling index (LI) after 17 days will be similar to that after 1 hr, and in this study twice as high as for the 1-hr interval since only one injection was given. However, experimental values only half that of the theoretical LI were found after 17 days. The following causes for the loss of labelled stem cells are discussed: (1) dilution of label because of division; (2) influx of unlabelled components of false pairs (i.e. newborn stem cells that still have to migrate away, mostly during G1, from their sister cells and are scored as Apr spermatogonia) between 1 hr and 17 days; (3) the existence of long- and short-cycling stem cells, probably combined with preferential differentiation of the short-cycling elements; (4) selective segregation of DNA at stem cell mitosis; and (5) irradiation death of radiosensitive labelled stem cells. As it is not impossible that factors 1, 2, 4 and 5 together account for the total loss of labelled stem cells, LI results do not provide evidence for the existence of separate classes of short- and long-cycling stem cells. The distributions of the LIs of the As, Apr and Aal spermatogonia over the stages of the epithelial cycle at 17 days are similar to those at 1 hr after injection. Hence the regulatory mechanisms that govern the stimulation and inhibition of proliferation of As that give rise to new As for the next epithelial cycle are similar to those of the As that will divide into Apr spermatogonia during the same epithelial cycle. Grain counts revealed that more [3H]TdR is incorporated into As, Apr and Aal spermatogonia that are in S phase during epithelial stages X-IV than in stages V-IX.

Spermatogonial multiplication in the Chinese hamster. II. Cell cycle properties of undifferentiated spermatogonia.

The cell cycle properties of undifferentiated spermatogonia in the Chinese hamster were analysed by the fraction of labelled mitoses technique (FLM) in whole mounted seminiferous tubules. The minimum cell cycle time (Tc) was found to be c. 90 hr for the As and 87 hr for the Apr and Aal spermatogonia, which is appreciably longer than for the differentiating types A2-B2 spermatogonia (60 hr). This is mainly accounted for by a longer tG1. In general the variability in the duration of the cell cycle phases is greater than for differentiating spermatogonia. From the shape and position of the second peak of the FLM curve it could be concluded that the undifferentiated spermatogonia either cycle with a Tc of c. 87-90 hr, or become arrested in G1. This implies that the decrease in proliferative activity of the undifferentiated spermatogonia after stage IV takes place by the arrest of progressively more cells, i.e. by a gradual decrease of the growth fraction, and not by a gradual lengthening of tG1. The arrested cells either differentiate into A1 spermatogonia and divide in stage IX, or remain undifferentiated and are stimulated to enter S again during the following epithelial cycle. It could be deduced from the heights of the second FLM peaks of As and Apr spermatogonia that once triggered into active cycle, the daughter cells of As spermatogonia that became Apr have a greater chance to continue cycling than those that became new As cells.

Safety of hospitalized ventilator-dependent children outside of the intensive care unit.

OBJECTIVE: Hospitalization of clinically stable ventilator-dependent children in an intensive care unit (ICU) remains the standard in most pediatric centers. The aim of this study was to determine whether chronically ventilator-dependent children could be hospitalized safely in a non-ICU setting. METHODS: All ventilator-dependent children who were hospitalized on the pediatric wards at Childrens Hospital Los Angeles from December 1992 through June 1996 were reviewed retrospectively (N = 63) and compared with the general pediatric ward population hospitalized during the same period. Data collected included the number of unexpected ICU transfers from the pediatric ward and the number of deaths that occurred on the ward. RESULTS: The ventilator-dependent children on the pediatric wards had 11 emergency readmissions to the ICU for unexpected deterioration. This represented an unexpected ICU transfer rate of 2.7 per 1000 patient-days on the wards. The general pediatric ward population had an unexpected ICU transfer rate of 3.3 per 1000 patient-days, which was not significantly different from that of ventilator-dependent children on the wards. There were three ward deaths among the ventilator-dependent children, but all of these patients had advance directive status (do not resuscitate). This represented a rate of seven deaths per 10,000 patient-days on the wards, which was not significantly different from those of nonventilator-dependent ward patients (eight deaths per 10,000 patient-days). CONCLUSIONS: We conclude that ventilator-dependent children hospitalized outside of the ICU do not have an increased incidence of deaths and unexpected ICU admissions compared with nonventilator-dependent inpatients. We speculate that hospital care of stable ventilator-dependent children can be provided safely outside of an ICU and at lower cost.

Heart rate variability in congenital central hypoventilation syndrome.

Heart rate variability was assessed in 12 patients with congenital central hypoventilation syndrome (CCHS) and in age- and sex-matched controls using SD of time intervals between R waves (R-R intervals), R-R interval histograms, spectral analysis, and Poincaré plots of sequential R-R intervals over a 24-h period using ambulatory monitoring. Mean heart rates in patients with CCHS were 103.3 +/- 17.7 SD and in controls were 98.8 +/- 21.6 SD (p greater than 0.5, NS). SD analysis of R-R intervals showed similar results in both groups (CCHS 102.2 +/- 36.0 ms versus controls 126.1 +/- 43.3 ms; p greater than 0.1, NS). Spectral analysis revealed that, for similar epochs sampled during quiet sleep and wakefulness, the ratios of low-frequency band to high-frequency band spectral power were increased for 11 of 12 patients with CCHS during sleep, whereas a decrease in these ratios was consistently observed in all controls during comparable sleep states (chi 2 = 20.31; p less than 0.000007). During wakefulness, the ratios of low-frequency band to high-frequency band spectral power were similar in both patients with CCHS and controls. Poincaré plots displayed significantly reduced beat-to-beat changes at slower heart rates in the CCHS patients (chi 2 = 24.0; p less than 0.000001). The scatter of points in CCHS Poincaré plots was easily distinguished from controls. All CCHS patients showed disturbed variability with one or more measures. The changes in moment-to-moment heart rate variability suggest that, in addition to a loss of ventilatory control, CCHS patients exhibit a dysfunction in autonomic nervous system control of the heart.

Meeting psychosocial and developmental needs of children during prolonged intensive care unit hospitalization.

In order to optimize psychosocial and cognitive development and family function of chronically ill patients who are acutely stable in a pediatric intensive care unit, the philosophy of care was changed. Psychosocial development was enhanced by practices that develop trust in caregivers, including change in visiting policies and consistency in caregivers. Cognitive development was enhanced by increasing interaction with the environment outside of the Pediatric Intensive Care Unit bed. Family function was maintained by communication and family participation.

Medical and psychosocial outcome of children with congenital central hypoventilation syndrome.

We report the long-term medical and psychosocial outcome of 13 children with congenital central hypoventilation syndrome. One child (8%) died before initial hospital discharge. Of the remaining 12 children, 11 (92%) have been successfully cared for in their natural or foster parents' homes. Home ventilatory support was provided with positive-pressure ventilation, negative-pressure ventilation, or diaphragm pacers. After an initial lengthy hospitalization, children spent little time in the hospital. Severe medical complications were uncommon but included cor pulmonale (one child), poor growth (two children), and seizure disorder (three children). Most children functioned in the slow-learner range of mental processing, with a composite score (Kaufman Assessment Battery for Children) of 78 +/- 20 (SD); two were mentally retarded, and one functioned above the normal range. The children's care givers were assessed as having low levels of psychologic distress (Symptom Checklist 90--Revised) and good coping resources (Coping Resources Inventory) but a high level of marital discord. The children were able to attend school and partake in normal childhood activities. We conclude that with modern techniques for home ventilation, children with CCHS can have a good long-term medical and psychosocial outcome. We speculate that early diagnosis and the prevention of intermittent hypoxia will improve their physical and mental outcome.