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Biomedical subjects

C Sullivan

Publications and source records attributed to C Sullivan.

At least 37 records · Page 2Linked to original sources
PubMed1998

Higher SaO2 in chronic neonatal lung disease: does it improve sleep?

Sleep fragmentation, decreased rapid eye movement (REM) sleep time, and REM sleep hypoxemia have been reported in infants with chronic neonatal lung disease (CNLD) in early infancy despite an awake hemoglobin oxygen saturation (SaO2) >93%. Interestingly, higher inspired O2 concentrations have been demonstrated to reduce REM sleep fragmentation in CNLD patients in middle infancy. However, the effect of increased SaO2 on sleep architecture in infants with CNLD near the time of discharge from neonatal intensive care has not been reported. We performed paired overnight polysomnography in a sleep laboratory on 16 infants with CNLD (4 weeks median corrected age) in air or their usual inspired oxygen (SaO2 >93%) and again when receiving 0.25 L/min higher than baseline inspired oxygen via nasal catheters (SaO2 >97%). A control group of seven healthy preterm infants was similarly studied. For CNLD infants on supplemented O2, sleep duration decreased by 15% (422+/-66 min vs. 359+/-89 min; P< 0.005), and sleep efficiency decreased by 7% (73.2+/-10.6% vs. 66.4+/-14.0%; P < 0.005) but percentage of time in REM sleep (REM%) (31.5+/-8.9% vs. 29.8+/-8.6%; P=0.560), REM epoch duration (12.4+/-2.8 min vs. 13.4+/-4.3 min; P=0.420), and REM arousal index (18.6+/-6.5 vs. 18.8+/-7.2; P=0.990) were not significantly affected. Conversely, higher O2 did not alter sleep architecture in the control group. The mean non-REM (NREM) respiratory rate decreased (CNLD: P=0.003; controls: P=0.02), NREM SaO2 increased (P < 0.05), although the mean transcutaneous CO2 was unaltered in both CNLD and control groups. This study confirmed low REM% in CNLD infants in early infancy and demonstrated that a higher SaO2 adversely affected sleep time but did not influence REM sleep duration or arousal frequency. A target SaO2 >93% is, therefore, as efficacious as an SaO2 >97% in optimizing sleep architecture in CNLD infants.

Bronchopulmonary Dysplasia↗
PubMed1998

Sleep, respiratory rate, and growth hormone in chronic neonatal lung disease.

This study assessed whether respiratory rates (RRs) correlate with urinary growth hormone (U-GH) excretion and sleep architecture in infants with chronic neonatal lung disease (CNLD) in early (1 month), middle (6 months), and late (10 months) infancy. Twenty-three preterm infants (CNLD=16, controls=7) were studied on 51 occasions. CNLD infants were stratified according to mean non-REM sleep respiratory rate (NREM RR) in early infancy into "High RR CNLD" infants (mean NREM RR >2 SD higher than controls) and "Normal RR CNLD" infants (mean NREM RR within 2 SD of controls' mean). "High RR CNLD" infants (RR >45) had a lower mean birthweight (P=0.015), current weight (P=0.042), current length (P=0.02), and growth velocity in early infancy (grams/week gained: P=0.042) than "Normal RR CNLD" and control infants. Mean (95% CI) U-GH excretion (ng U-GH/g urinary creatinine) was higher in "High RR CNLD" infants in air or their usual O2 (1,932 [459, 3,406]) than "Normal RR CNLD" (394 [147, 642]) and controls (320 [147, 492]) (P=0.024). With resolution of tachypnea by mid-infancy, hemoglobin oxygen saturation (SaO2) >93%, mean growth parameters and U-GH excretion for the "High RR CNLD" group were not significantly different from "Normal RR CNLD" and control groups. CNLD infants demonstrated increased sleep efficiency (P=0.016), whereas controls had similar sleep efficiency between early and middle infancy (P=0.452). Mean percent time in REM sleep (REM%) and slow wave sleep (SWS%) were not significantly different between early and middle infancy and did not vary in relation to respiratory rate. We conclude that tachypneic infants with CNLD have slower growth and elevated U-GH excretion in early infancy. With resolution of tachypnea, growth improved, U-GH excretion decreased, and sleep consolidation occurred. An elevated U-GH in tachypneic CNLD infants may reflect stress, compromised nutrition (GH resistance), or a feedback loop involving a direct effect of GH on lung growth and repair.

Bronchopulmonary Dysplasia↗
PubMed1998

Nongenetic mouse models of non-insulin-dependent diabetes mellitus.

The purpose of the study was to develop a mouse model of non-insulin-dependent diabetes mellitus (NIDDM) that closely simulates the metabolic abnormalities of the human disease and is also cost-effective compared with the genetic models currently available. For this purpose, insulin resistance was induced in male C57BL/6J or Institute of Cancer Research (ICR) mice by feeding diets enriched in either fructose or fat, and hyperglycemia was induced by injecting these mice with a dose of streptozotocin (STZ) that does not cause diabetes in chow-fed mice. In the case of C57BL/6J mice, insulin levels initially increased in response to the fructose- and fat-enriched diets and then decreased to levels comparable to or still higher than those in chow-fed mice following STZ injection. Associated with the decrease in insulin levels following STZ, fat-fed and fructose-fed C57BL/6J mice became significantly hyperglycemic, reaching values of 388 +/- 38 and 366 +/- 58 mg/dL, respectively. In contrast, neither plasma glucose nor insulin concentrations changed in chow-fed mice injected with an identical amount of STZ. Essentially identical findings were seen before and after STZ injection in fat-fed compared with chow-fed ICR mice. Although a direct comparison was not made, sensitivity to the diabetogenic effects of STZ appeared to be greater in fat-fed ICR compared with fat-fed C57BL/6J mice. Finally, plasma glucose decreased when mice with these experimental models of NIDDM were treated with either metformin or tolbutamide. Given these results, it seems reasonable to suggest that the combination of dietary-induced insulin resistance and relatively low-dose STZ results in mouse models that should be of use in studying the pathophysiology of NIDDM or in evaluating therapeutic compounds for the treatment of NIDDM.

Animals↗
PubMed1998

C2/3 instability in a child with Down's syndrome . case report and discussion.

Down's syndrome patients are prone to cervical ligamentous laxity, the vast majority of which is at the C1/2 level. We describe the case of a 2-year-old girl with Down's syndrome who was found to have cervical instability at the C2/3 level on screening cervical spine radiographs with 9 mm of anterolisthesis of C2 on C3. She was without clinically evident neurological deficit from this condition; however, T2-weighted magnetic resonance imaging of her cervical spine revealed high intensity signal changes within the spinal cord at and above that level. She underwent posterior fusion that was complicated by poor tolerance of her Minerva-type cervical brace. She eventually developed a stable fusion with 5 mm of anterolisthesis at the C2/3 level. This is the only Down's syndrome patient with instability at the C2/3 level that we have found reported. Our experience suggests that Down's syndrome patients can have instability at C2/3 that can be successfully treated with posterior fusion.

Cervical Vertebrae↗
PubMed1998

Moderate exercise during growth in prepubertal boys: changes in bone mass, size, volumetric density, and bone strength: a controlled prospective study.

Cross-sectional studies of elite athletes suggest that growth is an opportune time for exercise to increase areal bone mineral density (BMD). However, as the exercise undertaken by athletes is beyond the reach of most individuals, these studies provide little basis for making recommendations regarding the role of exercise in musculoskeletal health in the community. To determine whether moderate exercise increases bone mass, size, areal, and volumetric BMD, two socioeconomically equivalent schools were randomly allocated to be the source of an exercise group or controls. Twenty boys (mean age 10.4 years, range 8.4-11.8) allocated to 8 months of 30-minute sessions of weight-bearing physical education lessons three times weekly were compared with 20 controls matched for age, standing and sitting height, weight, and baseline areal BMD. Areal BMD, measured using dual-energy X-ray absorptiometry, increased in both groups at all sites, except at the head and arms. The increase in areal BMD in the exercise group was twice that in controls; lumbar spine (0.61 +/- 0.11 vs. 0.26 +/- 0.09%/month), legs (0.76 +/- 0.07 vs. 0.34 +/- 0.08%/month), and total body (0.32 +/- 0.04 vs. 0.17 +/- 0.06%/month) (all p < 0.05). In the exercise group, femoral midshaft cortical thickness increased by 0.97 +/- 0. 32%/month due to a 0.93 +/- 0.33%/month decrease in endocortical (medullary) diameter (both p < 0.05). There was no periosteal expansion so that volumetric BMD increased by 1.14 +/- 0.33%/month, (p < 0.05). Cortical thickness and volumetric BMD did not change in controls. Femoral midshaft section modulus increased by 2.34 +/- 2. 35 cm3 in the exercise group, and 3.04 +/- 1.14 cm3 in controls (p < 0.05). The growing skeleton is sensitive to exercise. Moderate and readily accessible weight-bearing exercise undertaken before puberty may increase femoral volumetric BMD by increasing cortical thickness. Although endocortical apposition may be a less effective means of increasing bone strength than periosteal apposition, both mechanisms will result in higher cortical thickness that is likely to offset bone fragility conferred by menopause-related and age-related endocortical bone resorption.

Age Determination by Skeleton↗
PubMed1998

The impact of the Interim Payment System: agency expectations.

How agencies approach the IPS reductions will have a profound impact on the future of home health under Medicare. A recent survey provides some preliminary information about how home health agencies expect the reimbursement changes to affect them.

Attitude of Health Personnel↗
PubMed1998

The long-term effects of battering on women's health.

We examined the effects of intimate violence on the physical and psychological health of women over time. Changes in levels of physical and psychological abuse, injuries, physical health symptoms, anxiety, and depression were assessed three times: immediately after exit from a domestic violence program and at 81/2- and 141/2-month follow-ups. Analyses showed a significant decline in abuse, physical health symptoms, anxiety, and depression over time. Longitudinal structural equation modeling demonstrated that ongoing abuse was significantly related to increased physical and psychological health problems from one time period to the next, even when prior levels of physical and psychological health were controlled. Within each time interval, the effects of abuse on physical symptoms appeared to be mediated through anxiety and depression; although this relationship was replicated at several time points, the mediation was not verified across time, probably because measurement intervals were too long to reflect the underlying causal sequence. Although injuries were the direct result of abuse, injuries showed no significant effect on physical symptoms, anxiety, or depression. Implications for intervention and future research are discussed.

Adult↗
PubMed1997

Introducing the cranial approach in osteopathy and the treatment of infants and mothers.

Osteopathy is one of the most commonly known treatments for lower back pain. However, media coverage is increasingly recognizing the potential of osteopathic care for a wide range of conditions across all age groups. In this article the role of osteopathic care in the treatment of pregnant mothers, the newborn and infants is considered. The aim of this paper is to stimulate further investigation by health care professionals into the potential benefits of osteopathic care for a range of clients. I have avoided lengthy technical aspects, hoping rather to expand on the thinking behind the approach, and welcome correspondence on any aspect of this paper. Unfortunately, there is a lack of good research evidence to data to support many of the claims and assertions made by osteopathy. However, with recent accreditation of the first Osteopathic MSc, a significant accumulation of such data over the next decade is anticipated.

Female↗
PubMed1996

Local TH1 and TH2 responses to parasitic infection in the intestine: regulation by IFN-gamma and IL-4.

Control of parasitic infections is dependent on the production of cytokines that activate mechanisms which limit invasion, reproduction or survival of the parasite. In contrast, conditions that induce inappropriate cytokine responses facilitate the spread of infection and ultimately exacerbate the level of disease. Measurement of local cytokine responses to different gastrointestinal parasites, such as the intracellular protozoan, Cryptosporidium parvum, and luminal dwelling nematodes like Nippostrongylus brasiliensis and Heligmosomoides polygyrus, reveal stereotype response patterns. In general, intracellular parasites stimulate type 1 responses where IFN-gamma is the predominant immune activator, while extracellular parasites stimulate type 2 responses where IL-4 plays a prominent role in elevating humoral immune mechanisms. Cytokines alter cellular function and the milieu of the intestinal lumen to affect the outcome of an infection. The importance of a particular response during the course of an infection can be studied by selective enhancement with an excess of exogenous recombinant cytokine or cytokine antagonists. For example, exogenous IL-12 enhances resistance to C.parvum, but suppresses the normally rapid cure of an infection with N. brasiliensis. Both mechanisms are dependent on expression of IFN-gamma. At the molecular level, exogenous IL-12 stimulates IFN-gamma production which elevates a protective type 1 response to C. parvum but converts the normally anti-worm type 2 response to a type 1 response that inappropriately regulates the infection. Alternatively, excess IL-4 plays a prominent role in modulating effector elements that change intestinal physiology to create a hostile environment for worm parasites. Exogenous IL-4 can cure chronic worm infection, while IL-4 antagonists interfere with protective responses to infection. These observations provide a paradigm for analysis of stereotype responses to different gastrointestinal parasites, and demonstrate how cytokine-induced immune system-dependent and independent effector mechanisms can limit parasitic infection, while inappropriate cytokine responses can exacerbate the state of disease.

Animals↗
PubMed1996

Outpatient biopsies of the palatine tonsil: access to lymphoid tissue for assessment of human immunodeficiency virus RNA titers.

OBJECTIVES: Our objective was to assess the feasibility of using tonsillar lymphoid biopsy specimens obtained on an outpatient basis to quantitate a patient's lymphoid human immunodeficiency virus (HIV) RNA titers. DESIGN: A pilot cohort study was performed. PATIENTS: We evaluated ten HIV-seropositive patients who ranged in age from 26 to 48 years and had CD4+ cell counts ranging from 110 to 833 at enrollment. MAIN OUTCOME MEASURES: The main outcome measures were tolerance and safety of outpatient tonsil biopsies and quantitation of HIV RNA titers in tonsillar lymphoid biopsy specimens, plasma, and peripheral blood mononuclear cells determined by a new method of HIV RNA signal amplification with branched DNA probes. RESULTS: Outpatient tonsil biopsies were well tolerated and were performed without complications. Nine of 10 tonsil biopsies from the HIV-seropositive patients examined were positive for significant concentrations of HIV RNA, ranging from 106 to 101 HIV RNA equivalents per gram of tissue. All of the HIV RNA-positive tonsillar lymphoid specimens had HIV RNA titers that were 101 to 104 times greater than those recovered from plasma (per milliliter) of the same patient obtained at the time of biopsy. CONCLUSIONS: Sufficient tonsillar tissue can be obtained in an outpatient clinic setting to quantitate lymphoid HIV titers by the new branched-DNA signal amplification method with relative ease and without complication. The biopsy method described here affords ready access to the lymphoreticular system, which may help to advance our understanding of the pathogenesis of myriad immune diseases without the need for excisional node biopsies.

Adult↗
PubMed1996

Separating the effects of alertness from the effects of encoding in a pitch-imagery task.

The facilitatory effects of auditory imagery have often been attributed to priming. However, the facilitatory effects of a prime on subsequent processing can be separated into effects related to specific perceptual processes, such as encoding, and effects related to more general processes, such as alertness. Whereas research on auditory imagery has focused on code-activated facilitation, the role of alertness in image-induced facilitation has been largely presumed rather than empirically investigated. Therefore, a study was designed to isolate the facilitatory effects of alertness from those of encoding. The results show that the nonspecific alerting effects of auditory imaging were quite extensive--a nearly 78-ms decrease in reaction time--compared with the effects of encoding.

Acoustic Stimulation↗
PubMed1996

Event-related brain potentials and attention during simultaneous performance of two tasks.

Subjects were required to perform simultaneously a compensatory manual tracking task and an auditory discrimination task. Four behavioral measures, root-mean-square-tracking error, reaction-time, Sensitivity and Response Bias, and two physiological measures, peak amplitudes and peak latencies of the "negative difference" even-related brain potential, were used to assess the distribution of attention during task performance. Approximately 200 msec. after stimulus onset (peak latency M = 206.6 msec.), the negative difference potential's peak amplitude was more positive for tones irrelevant to the discrimination task and less positive for tones relevant to the discrimination task. This pattern of change suggests that irrelevant tones receive less attention during simultaneous performance of the tasks than during performance of the discrimination task alone. Moreover, the data suggest that the redistribution of attention while simultaneously performing the tasks directly affects processing in the sensory areas of the auditory cortex.

Adolescent↗
PubMed1996

Distinct alterations in lineage committed progenitor cells exist in the peripheral blood of patients with rheumatoid arthritis and primary Sjogren's syndrome.

OBJECTIVE: Due to the elevated levels of hematopoietically active cytokines such as tumor necrosis factor (TNF) and granulocyte macrophage colony stimulating factor (GMCSF) in rheumatoid arthritis (RA) serum and synovium, the increased bone marrow activity in RA, and the effectiveness of GMCSF in mobilizing progenitor cell release from the bone marrow into the periphery, we hypothesized that hematopoietic progenitors are altered in the peripheral blood (PB) of patients with RA. METHODS: Flow cytometry assisted cell surface analysis was employed to compare the distribution of myeloid (CD34+CD33+), B lymphoid (CD34+CD10+), and erythroid (CD34+CD71+) committed progenitor cell subsets in the PB of healthy controls and patients with RA. Since RA and Sjogren's syndrome (SS) are related autoimmune disorders, primary SS PB was also investigated. RESULTS: Only those patients with RA exhibiting clinically active disease (RA-A) demonstrated increases in myeloid and B lymphoid progenitor cell subsets. Growth of RA-A progenitors in cytokines promoting myelopoiesis (GMCSF, TNF, stem cell factor) produced increased monocyte and dendritic cell progeny, in support of the flow cytometry data. Lineage committed (CD34+CD38+) progenitors were increased in SS PB (p <0.03). However, these did not correlate with either the myeloid, erythroid, or B lymphoid lineages. CONCLUSION: Distinct alterations in the distribution of PB progenitors are present in RA and primary SS. Since progenitor cells retain a proliferative capacity, their infiltration into the synovial/glandular environment may contribute to the accumulation of inflammatory cells within these sites. We propose that PB progenitors enter the diseased microenvironment through similar mechanisms as mature hematopoietic elements.

ADP-ribosyl Cyclase↗