Inflammation mediates the association between visceral adiposity and obstructive sleep apnea in adolescents

Only a handful of studies, primarily in clinical samples, have reported an association between obesity, inflammation, and obstructive sleep apnea (OSA) in children and adolescents. No studies, however, have examined the pathogenetic link between visceral adiposity, systemic inflammation, and incident OSA in a large general population sample using objective measures of sleep and body fat. Adolescents (n = 392; mean age 17.0 ± 2.2 yr, 54.0% male) from the Penn State Child Cohort (PSCC) underwent 9-h overnight polysomnography; a DXA scan to assess body fat distribution; and a single fasting blood draw for the assessment of plasma interleukin-6 (IL-6), IL-6 soluble receptor (IL-6 sR), tumor necrosis factor alpha (TNFα), tumor necrosis factor receptor 1A (TNFR1), C-reactive protein (CRP), leptin, and adiponectin levels via ELISA. Visceral fat area was significantly elevated in moderate OSA (AHI ≥ 5), especially in boys. IL-6, CRP, and leptin were highest in adolescents with moderate OSA, even after adjusting for BMI percentile. Mediation analysis revealed that 42% of the association between visceral fat and OSA in adolescents was mediated by IL-6 (p = 0.03), while 82% of the association was mediated by CRP (p = 0.01). These data are consistent with the model of a feed-forward, vicious cycle, in which the release of proinflammatory cytokines by visceral adipocytes largely explains the association between central obesity and OSA; in turn, inflammation is also elevated in OSA independent of BMI. These findings, in a large, representative, non-clinical sample of young people, add to our understanding of the developmental pathogenesis of sleep apnea.

Abdominal obesity and metabolic syndrome burden in adolescents--Penn State Children Cohort study

To investigate the association between abdominal obesity and metabolic syndrome (MetS) burden in a population-based sample of adolescents, we used data from 421 adolescents who completed the follow-up examination in the Penn State Children Cohort study. Dual-energy x-ray absorptiometry (DXA) was used to assess abdominal obesity, as measured by android/gynoid fat ratio (A/G ratio), android/whole body fat proportion (A/W proportion), visceral (VAT) and subcutaneous fat (SAT) areas. Continuous metabolic syndrome score (cMetS), calculated as the sum of the age and sex-adjusted standardized residual (Z-score) of five established MetS components, was used to assess the MetS burden. Linear regression models were used to analyze the impact of DXA measures on cMetS components. All models were adjusted for age, race, sex, and general obesity. We found abdominal obesity is significantly associated with increased cMetS. With 1 standard deviation (SD) increase in A/G ratio, A/W proportion, VAT area, and SAT area, cMetS increased by 1.34 (SE=0.17), 1.25 (SE=0.19), 1.67 (SE=0.17), and 1.84 (SE=0.20) units, respectively. At individual component level, strongest association was observed between abdominal obesity and insulin resistance (IR) than lipid-based or blood pressure-based components. VAT and SAT had a stronger impact on IR than android ratio-based DXA measurements. In conclusion, abdominal obesity is associated with higher MetS burden in adolescent population. The association between abdominal obesity and IR measure is the strongest, suggesting the key impact of abdominal obesity on IR in adolescents MetS burden.

Ischemic colitis in young adults: a single-institution experience

Ischemic colitis is not well characterized in the young adult population, despite its commonness in older patients. The aim of this study was to investigate the demographics, etiology, clinical features, and prognosis of ischemic colitis in young adults. We conducted a retrospective study of 39 young adults (<50 years of age) diagnosed with ischemic colitis over a period of 9 years (1990 to 1998). The mean age at diagnosis was 38 +/- 2 years (range 18 to 49 years); the female:male ratio was 1.8. Fifty-two percent (13 of 25) of women were using oral contraceptives at the time of diagnosis. Other potential associations identified were vascular thromboembolism (4 of 39), vasoactive drugs (4 of 39), hypovolemia (4 of 39), and vasculitis (2 of 39); 19 patients (49%) had no identifiable predisposing factors. Dominant presenting symptoms were abdominal pain (77%), bloody diarrhea (54%), and hematochezia (51%). Most patients were diagnosed at colonoscopy, and most disease was left sided. Twenty-nine patients were successfully managed with intravenous fluids, broad-spectrum antibiotics, and bowel rest; 10 patients required surgery. There was one disease-related death in the operative group. We found a strong female predominance and an association with oral contraceptive use, but almost half of the patients did not have an identifiable etiology. Mortality from ischemic colitis in this patient population is low.

Novel potentiation of interleukin 1alpha production in endotoxin-stimulated IC-21 cells by ambient pressure augmentation

BACKGROUND

We hypothesized that increased ambient pressure would increase the production of interleukin 1alpha by endotoxin-stimulated macrophages, based on the clinical observation that patients with "pus under pressure" demonstrate systemic toxic effects (a priori hypothesis).

DESIGN AND SETTING

In vitro experiment in the laboratory.

INTERVENTIONS

A murine macrophage line, IC-21 cells, was seeded into 6-well plates, 25 x 10(4) cells per well. Cells were incubated under atmospheric (ATM) or increased (ATM+60 mm Hg) ambient pressure (AP) in the presence or absence of endotoxin (lipopolysaccharide [LPS]). The IC-21 production of interleukin 1alpha was determined at 2, 4, 8, and 12 hours. Four groups were examined: group 1: AP ATM, no LPS; group 2: AP ATM+60 mm Hg, no LPS; group 3: AP ATM and LPS, 500 ng/mL; and group 4: AP ATM+60 mm Hg and LPS, 500 ng/mL.

MAIN OUTCOME MEASURES

The IC-21 production of interleukin 1alpha.

RESULTS

Interleukin 1alpha production at 2, 4, 8, and 12 hours (mean [+/-SD] picograms per 10(6) cells) was as follows: group 1: 3.0 (+/-5.9), 8.1 (+/-10.3), 50.5 (+/-51.1), and 6.1 (+/-4.1), respectively; group 2: 228.7 (+/-110.2), 141.0 (+/-141.8), 112.5 (+/-98.5), and 118.2 (+/-79.8), respectively; group 3: 37.2 (+/-13.3), 191.5 (+/-86.5), 627.3 (+/-184.3), and 600.7 (+/-67.1), respectively; and group 4: 601.2 (+/-49.9), 1050.9 (+/-190.6), 2684.2 (+/-562.2), and 3144.7 (+/-388.4), respectively. The production of IL-1alpha by group 3 was significantly greater (P<.04, unpaired Student t test) at 4, 8, and 12 hours than that by groups 1 or 2. Likewise, the production of IL-1alpha by group 4 was significantly greater (P<.001, unpaired Student t test) at all time points than that by groups 1, 2, or 3.

CONCLUSIONS

Our data support the hypothesis that pressure may be a novel potentiator of the macrophage proinflammatory cytokine response to endotoxin. This provides a possible explanation for the phenomenon of systemic illness seen with "pus under pressure."

Enteric absorption of ciprofloxacin during tube feeding in the critically ill

To determine the pharmacokinetic properties of ciprofloxacin in the critically ill, we studied seven mechanically ventilated patients with pneumonia during enteral feedings. Subjects received ciprofloxacin 750 mg every 12 h via nasogastric tube and serial serum drug concentrations were measured after the first and fourth dose. After the initial dose, the maximum serum concentration ranged from 1.24-3.06 mg/L, and the area under the time curve from 0-12 h ranged from 3.2-19.65 mg.h/L. Similar levels were noted after dose four. Gastrointestinal absorption of ciprofloxacin in tube fed critically ill patients was decreased, but well above MIC values for many pathogenic bacteria.

Transcriptional regulation of endothelin

Three isoforms of endothelin (ET) exist, ET-l, ET-2,and ET-3.Nucleotide sequences for the three human ET genes are highly conserved. ET-l exactly matches the sequence ofET originally isolated from the condi- tioned medium of cultured bovine aortic endothelial cells (BAECs)."All three forms have been found in vascular, neural, adrenal, and kidney tissue, but are expressed in different proportions. Endothelial cells ex- clusively produce ETAll three isoforms have different vasoconstrictive potencies but are otherwise quali- tatively similar. ET-2 is the most potent vasoconstrictor, followed by ET-l and ET.

Esmarch closure of laparotomy incisions in unstable trauma patients

Fascial closure after laparotomy may be time-consuming and extremely difficult, especially in the setting of massive bowel edema. In the trauma patient with deteriorating hemodynamic status, hypothermia, or worsening hypoxia, expeditious abdominal wall closure is essential to facilitate rapid transport to the intensive care unit for further stabilization. With the increasing utilization of the abbreviated laparotomy in unstable trauma patients, innovative techniques for speedy fascial closure must be evaluated. We developed the Esmarch closure--a simple, rapid method for closing the abdominal wall at the end of abbreviated laparotomies.

Treatment of recurrent cytomegalovirus disease in patients receiving solid organ transplants

Tissue-invasive cytomegalovirus (TI-CMV) disease occurs commonly after solid organ transplantation and has been associated with increased allograft loss and patient mortality. Although ganciclovir has been demonstrated to be an effective form of treatment for TI-CMV disease, therapy may be followed by recurrence. The purpose of this study was to determine the impact of recurrent TI-CMV disease on patient and allograft survival. We studied 619 patients who underwent solid organ transplantation (535 kidney transplants [253 from living related donors and 282 from cadavers] and 84 combined cadaveric kidney-pancreas transplants) during a 3 1/2-year period. One hundred fourteen patients (18.4%) developed TI-CMV disease and were treated with a standardized regimen of intravenous ganciclovir for 14 to 21 days. Of the 114 patients in whom primary TI-CMV disease developed, 28 (24.6%) developed recurrent TI-CMV disease more than 30 days after the initial episode, and these patients were retreated with ganciclovir. Cure rates at 30 days were 98.9% in patients with primary TI-CMV disease and 100% in patients with recurrent TI-CMV disease. Patients who underwent cadaveric kidney or kidney-pancreas transplantation were more likely to develop recurrent TI-CMV disease than were recipients of kidney transplants from living related donors; antirejection therapy also was associated with a higher incidence of recurrent TI-CMV disease. Patients who developed TI-CMV disease exhibited lower rates of graft and patient survival at 3 years than patients without TI-CMV disease or with solely asymptomatic CMV infection, although recurrent TI-CMV disease did not appear to exacerbate morbidity or mortality. We conclude that recurrent episodes of TI-CMV disease do not appear to further adversely affect patient or graft survival in comparison with primary TI-CMV disease in ganciclovir-treated patients.

Antimicrobial therapy of intra-abdominal sepsis

Intra-abdominal sepsis remains a highly morbid and lethal event despite the availability of potent antimicrobial agents and improvements in surgical management and intensive care. Appropriate management consists of source control, antimicrobial agents directed against both facultative gram-negative and anaerobic organisms, and physiologic and metabolic support. A variety of single and dual agent regimens are appropriate for initial therapy, as long as both aerobes and anaerobes are effectively targeted. Culture, Gram stain, and sensitivity testing may provide valuable information, especially when resistant organisms are encountered. Further studies to determine the relative efficacy of various agents need to be carefully designed both to avoid the pitfalls of previous studies and to provide useful and comparable data.

Appropriate use of antimicrobial agents. Nine principles

After determining that a patient with an infection would benefit from an antimicrobial agent, several factors must be weighed to arrive at an appropriate choice: seriousness of the infection, the patient's drug allergies, and drug efficacy, toxicity, and cost. Rapid stains, cultures, and sensitivity studies are often helpful in guiding therapy and are critical to appropriate treatment of serious infections. Consideration should also be given to other forms of management, such as control of the source of infection, prophylaxis, and physiologic management.

Antigenic alterations in autoimmune thyroid diseases. Observations and hypotheses

In order to further define the pathobiologic changes that occur in Hashimoto's thyroiditis (HT) and Graves' disease (GD), 47 cases of these conditions and six of nodular thyroid hyperplasia were studied. Antibodies to cytokeratin, vimentin, LN-2 (a B-lymphocyte marker), UCHL-1 (a T-lymphocyte marker), and HLA-DR, and biotinylated Helix pomatia (Roman snail) lectin, were applied to paraffin sections using the avidin-biotin-peroxidase complex method. Cytokeratin was not expressed in resting epithelium or nodular hyperplasia, but was strongly displayed by injured (HT) or diffusely hyperplastic (GD) glandular tissue. Vimentin was present throughout the cytoplasm of proliferating thyrocytes but was limited to basal portions of resting cells and those of nodular hyperplasia. HLA-DR was observed in injured and hyperplastic thyroid tissue, as was N-acetyl-alpha-D-galactosamine, the target of H pomatia lectin. UCHL-1-labeled infiltrating lymphocytes were observed in both HT and GD, in areas with minimal epithelial changes, while LN-2 was observed only in association with well-formed lymphoid follicles. These findings suggest that T cells are implicated in the mechanism of both conditions, but that inflammation is not the initiating event for HT and GD; and that a "switch" in intermediate filament synthesis accompanies HLA-DR and N-acetyl-alpha-D-galactosamine expression by thyroid epithelium. Since current theories implicate intermediate filaments as intracellular mediators, we hypothesize that certain cytokeratins may be associated with gene activity governing the expression of class II histocompatibility antigens and other membrane glycoproteins in HT and GD.

Lymphokine-activated killer (LAK) cells can be focused at sites of tumor growth by products of macrophage activation

Successful adoptive cancer immunotherapy presumably depends on the accumulation of tumoricidal leukocytes at the sites of tumor growth. Large numbers of lymphokine-activated killer (LAK) cells can be generated in vitro by growth in high concentrations of interleukin-2 (IL-2), but relatively few arrive at the tumor site after intravenous injection. We hypothesize that the delivery of LAK cells to tumor sites may be augmented by previously demonstrated lymphocyte-recruiting factors, including activated macrophage products such as interleukin-1 (IL-1) and tumor necrosis factor. 111Indium-labeled LAK cells were injected intravenously into syngeneic mice bearing the macrophage activator endotoxin (LPS) in one hind footpad, and saline solution was injected into the contralateral footpad. Significantly more activity was recovered from the LPS-bearing footpad at all times during a 96-hour period. Recombinant IL-1 also attracted more LAK cells after injection into tumor-free hind footpads. Furthermore, LAK cells preferentially homed to hind footpads that were bearing 3-day established sarcomas after intralesional injections of LPS, IL-1, or tumor necrosis factor when compared with contralateral tumor-bearing footpads injected with saline solution alone. In preliminary experiments, mice with hind-footpad tumors appeared to survive longer after combined systemic IL-2 and LAK therapy if intralesional LPS was administered. These studies demonstrate that macrophage activation factors that have been shown capable of attracting circulating normal lymphocytes can also effectively attract LAK cells from the circulation. By the stimulation of macrophages at the sites of tumor growth, more LAK cells can be attracted. It is hoped that by "focusing" the migration of LAK cells to tumors, LAK cells and IL-2 would effect tumor regression more efficiently and with less toxicity.