Participant-collected household dust for assessing microorganisms and semi-volatile organic compounds in urban homes

Dust samples collected by researchers and study participants from 43 U.S. urban homes were analyzed and compared to evaluate the feasibility of using participant-collected samples to assess indoor environmental exposures. The microbial and chemical composition of participant-collected (and shipped) samples were compared to researcher-collected samples from the same household, using dust recovered from each home's heating, ventilation, and air conditioning (HVAC) filter. The bacterial and fungal communities present in all dust samples were determined via MiSeq 16S and ITS sequencing, and the concentrations of 27 semi-volatile organic compounds (7 orthophosphates, 6 phthalates, and 14 brominated flame retardants) were determined via GC-MS. Self-report data on the home environment was collected via an online survey of study participants. While the researcher-collected samples (RCS) yielded greater mass than the participant-collected samples (PCS), the alpha and beta diversities of the bacterial and fungal communities recovered in the RCS and PCS were not significantly different, indicating that PCS is a viable option for indoor microbiome studies of residential homes. The microbial communities recovered in both cases reflected the dominance of human-associated bacterial taxa and outdoor-associated fungal taxa with similar pathogen-associated taxa present in each sample type. In both PCS and RCS, the amount of carpet in the home and the frequency of bleach use had a significant effect on the composition of fungal communities. Semi-volatile organic compounds (SVOCs) of potential human health concern, were commonly detected in the homes. Organophosphates and phthalates were recovered at a similar frequency in both PCS and RCS. Measured SVOC concentration levels were consistent with previous indoor studies although differences were observed between PCS and RCS for several SVOCs. This study demonstrates the potential and challenges associated with participant-collected dust samples for indoor environment studies.

Acarbose treatment of postprandial hypoglycemia in children after Nissen fundoplication

Dumping syndrome and postprandial hypoglycemia have been reported after Nissen fundoplication. The physiopathologic mechanisms are poorly understood and a variety of therapies have failed to control the hypoglycemia in these patients. We report a series of 6 infants with postprandial hypoglycemia after Nissen fundoplication who were treated successfully with acarbose.

Determination of hexazinone in groundwater by direct-injection high-performance liquid chromatography

Hexazinone has been detected at levels ranging from 0.2 to 50 micrograms/L in many groundwater samples from eastern Maine over the past decade. A rapid and inexpensive direct-injection high-performance liquid chromatographic (HPLC) method has been developed to monitor contamination levels of the herbicide. The method is sensitive (limit of quantitation = 0.33 microgram/L) and is linear to 33.0 micrograms/L (R2 = 0.9995). Direct injection results from 50 field samples compared well (R2 = 0.98) with an HPLC method using solid-phase extraction for concentration and cleanup. The technique is very reproducible (coefficients of variation of 0-8.4% within day and 3.0-13.2% between day) and eliminates loss of analyte because of fewer steps in the procedure.

Suppression of insulin oversecretion by subcutaneous recombinant human insulin-like growth factor I in children with congenital hyperinsulinism due to defective beta-cell sulfonylurea receptor

Congenital hyperinsulinism (HI) is the most common cause of persistent hypoglycemia in infants under 1 yr of age. HI is most often due to defective glucose-insulin coupling by the beta-cell sulfonylurea receptor (SUR1) or glutamate dehydrogenase. HI-induced hypoglycemia carries significant morbidity, and current therapies are suboptimal. Insulin-like growth factor I (IGF-I) decreases insulin secretion in vitro and in healthy adults in vivo. We postulated that recombinant human IGF-I (rhIGF-I) could benefit children with HI and hypoglycemia by decreasing insulin levels and improving fasting tolerance. We enrolled nine subjects in an open label trial of rhIGF-I: eight children, ages 1 month to 11 yr, with HI due to identified mutations of SUR1 (n = 5) or clinically unresponsive to diazoxide, which acts via the SUR (n = 3), and one adult, age 32 yr, with HI due to defective glutamate dehydrogenase-1. All had suboptimal glycemic control and served as their own controls. Subjects underwent 24-h glucose monitoring under their home regimens, followed by a supervised fasting study. The controlled fast was terminated when the subject became hypoglycemic (blood glucose, <50 mg/dL) or developed symptoms consistent with hypoglycemia. The fast was repeated 2 days later with administration of rhIGF-I at 40 microg/kg, s.c., every 12 h. At the start of fasting rhIGF-I lowered the mean serum insulin level by 70% (21.0 +/- 11.1 vs. 6.3 +/- 2.2 microIU/mL; P < 0.04) and lowered the mean serum C peptide level by 43% (2.1 +/- 0.7 vs. 1.2 +/- 0.6 ng/mL; P < 0.04). rhIGF-I suppression of insulin and C peptide persisted throughout the fast. The duration of fasting did not change significantly with rhIGF-I treatment. We have directly demonstrated that rhIGF-I inhibits insulin oversecretion in children with HI due to defective SUR1. Our data suggest that IGF inhibition of insulin secretion does not require an intact SUR. rhIGF-I is unlikely to be effective monotherapy for HI, but may provide synergy to inhibit insulin secretion when combined with agents acting via IGF-independent mechanisms.

Comparison of two concentrations of amphotericin B bladder irrigation in the treatment of funguria in patients with indwelling urinary catheters

The efficacy of amphotericin B bladder irrigation at two concentrations was studied. Patients with funguria (> or =15,000 colony-forming units of yeast per milliliter of urine), an indwelling urinary catheter, and a physician order for amphotericin B continuous bladder irrigation were randomly assigned to receive 10 or 50 mg of amphotericin B per liter of sterile water as a continuous irrigation for 72 hours at the rate of 42 mL/hr. Before the bladder irrigation began, the indwelling catheter was changed to a three-way catheter. Repeat urine cultures were performed 24 hours after the irrigation was discontinued. A total of 28 patients were enrolled from November 1993 to May 1995. The rate of eradication of the infection was 100% in the 50-mg/L group and 67% in the 10-mg/ L group. Subject enrollment was stopped prematurely because all the treatment failures occurred in the 10-mg/L group. Dose was the only variable significantly associated with outcome. Bladder irrigation with amphotericin B was more effective when the drug concentration was 50 mg/L rather than 10 mg/L.

Cellular actions of insulin-like growth factor binding proteins

The insulin-like growth factors (IGFs), insulin-like growth factor binding proteins (IGFBPs), and the IGFBP proteases are involved in the regulation of somatic growth and cellular proliferation both in vivo and in vitro. IGFs are potent mitogenic agents whose actions are determined by the availability of free IGFs to interact with the IGF receptors. IGFBPs comprise a family of proteins that bind IGFs with high affinity and specificity and thereby regulate IGF-dependent actions. IGFBPs have recently emerged as IGF-independent regulators of cell growth. Various IGFBP association proteins as well as cleavage of IGFBPs by specific proteases modulate levels of free IGFs and IGFBPs. The ubiquity and complexity of the IGF axis promise exciting discoveries and applications for the future.

Dual regulation of insulin-like growth factor binding protein-1 levels by insulin and cortisol during fasting

Insulin-like growth factor (IGF) binding protein-1 (IGFBP-1) gene transcription is known to be inhibited by insulin in vivo and in vitro. Levels of IGFBP-1 typically rise during fasting but also rise after acute hypoglycemia, including that induced by insulin, through an unknown mechanism that may involve counterregulatory hormones such as cortisol. To study the regulation of IGFBP-1 secretion during fasting, we measured IGFBP-1, insulin, cortisol, GH, and glucose during the course of standardized fasting studies in a total of 21 children. The fasting studies lasted 13-32 h and were terminated for a whole-blood glucose concentration of less than 50 mg/dL (2.8 mmol). Of the children studied, 9 children had no disorder, 8 had ketotic hypoglycemia, 2 had isolated GH deficiency, and 2 had fatty acid oxidation disorders. During fasting, IGFBP-1 rose above the mean baseline levels of 28+/-5 ng/mL to a mean level+/-SEM of 336+/-59 ng/mL at the time of hypoglycemia (P=0.001). IGFBP-1 was strongly associated with serum insulin and cortisol levels over the entire course of fasting (P < 0.0001)). The interaction of the 2 hormones across time was also strongly significant (P < 0.0001). There was no statistically significant association between IGFBP-1 and GH or glucose. At the time of hypoglycemia, insulin levels were suppressed to 1.7 microU/mL or less, and there was no correlation between IGFBP-1 levels at the end of fasting and final insulin level. In contrast, cortisol levels correlated with IGFBP-1 in the final hypoglycemic sample (r=0.56, P < 0.01). Partial correlation analysis revealed that the relationship between IGFBP-1 and cortisol was unchanged when the data was controlled for insulin levels. These data show that insulin and cortisol both regulate IGFBP-1 secretion during fasting; the effects of insulin and cortisol are strong during the course of fasting. Significant hypoglycemia stimulates a further rise in IGFBP-1, which seems to be regulated, in part, by cortisol. The cortisol-induced rise in IGFBP-1 during fasting and during hypoglycemia potentially serves to prevent the hypoglycemic effects of free IGFs.

IGF-II, IGF-binding proteins and IGF receptors in pancreatic beta-cell lines

The IGFs are mitogenic agents which are closely linked to regulatory processes in carbohydrate metabolism. Because limited information is available on the occurrence of the IGF system in the pancreatic beta-cell milieu, we evaluated the presence of IGFs, IGF receptors, and IGF-binding proteins (IGFBPs) in the beta-cell lines beta TC3 and HIT T-15. Serum-free conditioned media (SFCM) from beta TC3 cells contained IGF-II at concentrations greater than 100 ng/ml. High (15 kDa) and low (7.5 kDa) molecular weight IGF-II were detected both by column chromatography followed by RIA and by immunoblotting. GH (10-1000 ng/ml) conditioning of beta TC3 cells stimulated IGF-II secretion in a dose-dependent manner. IGF-II mRNA was detected in beta TC3 cells using Northern blots, and also showed a GH-dependent relationship. IGF-II peptide was detected in SFCM from HIT cells, albeit at lower concentrations. To evaluate the presence of IGF receptors in beta-cell lines, affinity cross-linking studies were performed on beta TC3 cells, demonstrating type I IGF receptors which bound iodinated IGF-II with high affinity, iodinated IGF-I with lesser affinity, and had minimal appreciable binding to iodinated insulin. Type II IGF receptors were not detected. SFCM from beta TC3 and HIT cells was subjected to Western ligand blotting, which disclosed the presence of two major IGFBPs of 29 kDa and 24 kDa, characteristic of IGFBP-2 and IGFBP-4. The identity of the specific IGFBPs was confirmed by immunoprecipitation and Northern blotting. Varying the glucose concentration had no significant effect on the levels of IGFBPs, nor did preconditioning with GH, IGF-I, IGF-II, insulin, or glucagon. Levels of both IGFBPs in beta TC3 cell-conditioned media increased in the presence of dexamethasone at concentrations of 10(-6) M or greater. In summary, we present evidence that beta-cell lines comprise an environment for GH and IGF action. We speculate that IGFs, their receptors and binding proteins function as a complex interactive system which regulates beta-cell growth and function.

The effect of growth hormone treatment on the insulin-like growth factor axis in a child with nonislet cell tumor hypoglycemia

We have previously described a case of tumor-associated hypoglycemia secondary to the production of high molecular weight insulin-line growth factor (IGF)-II in a child with congenital neuroblastoma. The child's hypoglycemia resolved with GH therapy and has continued to be well controlled for 1 yr. This represents one of the first cases of nonislet cell tumor hypoglycemia (NICTH) treated successfully with long-term exogenous GH. We now present an in-depth analysis of the IGF axis in this patient, before and after GH treatment. Although IGF-II levels at presentation were in the normal range, they were inappropriate for the patient's low GH state. Furthermore, the percentage of "big" IGF-II was elevated, as was the level of the IGF-IIE peptide, which is normally cleaved in the processing of the mature peptide. On the initial evaluation, GH levels failed to rise in response to hypoglycemia, IGF-I levels were low, IGF binding protein-3 (IGFBP-3) levels were suppressed, and IGFBP-2 levels were elevated. We have shown that baseline IGFBP-3 levels were low by RIA and immunoblotting and have demonstrated that this decrease was not associated with IGFBP protease activity. We have also demonstrated the baseline suppression of the acid labile subunit (ALS) of the 150K ternary complex by a novel immunoblot assay. The ratio of IGFs to IGFBP-3 was dramatically elevated, presumably leading to hypoglycemia. Furthermore, the percentage of serum IGF-I and IGF-II present as part of a binary (50K) complex with IGFBPs was also increased. GH therapy resulted in a normalization of the levels of blood sugars, IGFBP-3, ALS, IGFBP-2, and IGF-I, as well as the IGF/IGFBP-3 ratio. In summary, we have presented evidence that the hypoglycemia in this patient resulted from tumor production of high molecular weight IGF-II, which suppressed GH secretion, leading to the described derangements in the IGF binding proteins. We speculate that as a result of the decreased IGFBP-3 and ALS levels, the IGF population was shifted from the stable 150K complex to lower molecular weight complexes with IGF binding proteins, increasing IGF availability to tissues due to rapid turnover of these low molecular weight complexes. We demonstrated the reversal of the abnormalities in the IGFBP levels with GH treatment, corresponding to the clinical response of euglycemia.

Non-islet-cell tumor associated with hypoglycemia in a child: successful long-term therapy with growth hormone

Hypoglycemia occurred in a 2-year-old girl with neuroblastoma. Initially, growth hormone secretion was suppressed, and she had low levels of insulin-like growth factor (IGF)-I and IGF binding protein-3, but elevated levels of large molecular weight IGF-II. We postulated that the pathogenesis of her hypoglycemia involved production of IGF-II by her neuroblastoma, leading to GH suppression and an abnormally elevated ratio of IGF to IGF binding protein. She was successfully treated with growth hormone; treatment was associated with normalization of the growth hormone-dependent growth factor levels and with euglycemia.

The new highly sensitive adrenocorticotropin assay improves detection of patients with partial adrenocorticotropin deficiency in a short-term metyrapone test

This study was designed to evaluate a short term metyrapone test using a highly sensitive (HS) IRMA ACTH assay and to evaluate the usefulness of a morning ACTH level as a screening test for partial ACTH deficiency. ACTH, 11-deoxycortisol and cortisol levels were evaluated over four hours in the morning after a single 40 mg/kg oral dose of metyrapone was administered at 0800 hours. 26 control children and 32 possibly pituitary deficient patients were evaluated. Based on 11-deoxycortisol levels alone, 17 of the patients passed the test, 11 patients failed the test and the result was inconclusive in four patients (12.5%). Evaluation of the increase in ACTH levels (delta ACTH) following metyrapone identified three of the above four with partial ACTH deficiency. The delta ACTH was consistent with the 11-deoxycortisol results in the remainder of patients. There was no difference in morning ACTH levels between controls and patients with partial ACTH deficiency. The measurement of ACTH using the HS IRMA assay, increases the sensitivity of the metyrapone test in detecting patients with partial ACTH deficiency. This test may be used safely in pediatric patients on a repetitive basis, especially in those children who may have progressive ACTH failure following hypothalamic-pituitary irradiation.

Short- and long-term use of octreotide in the treatment of congenital hyperinsulinism

Octreotide, a long-acting analog of somatostatin that inhibits insulin release, has the potential to control hypoglycemia in infants with congenital hyperinsulinism. To examine the efficacy and side effects of octreotide, we evaluated therapy between 1988 and 1993 in 16 infants who did not respond to diazoxide. In nine patients with onset of severe hypoglycemia in the first days of life, octreotide was helpful in stabilizing plasma glucose levels and allowed reductions in the rates of glucose infusion; however, glucose control was inadequate to avoid subtotal pancreatectomy. In two of these nine patients postoperatively and in seven other infants, a trial of long-term treatment with octreotide was undertaken. Four were treated successfully for up to 4.3 years. Octreotide therapy was not associated with thyroid deficiency and caused only transient malabsorption. All patients receiving long-term therapy had some decrease in linear growth and two had subnormal plasma concentrations of insulin-like growth factor I and insulin-like growth factor binding protein 3 compatible with suppression of growth hormone by octreotide. Resistance to octreotide therapy, even with increasing doses, occurred in all patients. These results suggest that octreotide may aid in the acute or long-term treatment of congenital hyperinsulinism in a limited number of selected cases.

Low loss Si(3)N(4)-SiO(2) optical waveguides on Si

We have developed an optical integrated circuit waveguide technology based on conventional Si processing. We demonstrate waveguide losses of <0.3 dB/cm in the 1.3-1.6-microm wavelength range. We use a high refractive-index core of Si(3)N(4) surrounded by SiO(2) cladding layers, which provides a highly confined optical mode adequate for butt coupling to channel substrate buried heterostructure lasers. We report the first IR transmission experiments in these waveguides and find two absorption peaks associated with H in SiO(2) and Si(3)N(4) layers at 1.40 and 1.52 microm, respectively. The peak absorptions are 2.2 and 1.2 dB/cm, respectively, and these peaks can be largely removed by annealing at 1100-1200 degrees C.

AANA Journal Course. 2. Cardiovascular system. The anesthetic management of the patient: a focus on myocardial infarction

Although it is important to note the cardiovascular effects of the various anesthetic agents, the anesthetist should use the anesthetic agent with which he or she is most familiar and with which it is felt that the best control of cardiovascular parameters can be maintained. It should be remembered that the effects of all drugs are dependent upon the milieu into which the drug is given. Expected effects may be altered because of the patient's cardiac and/or related pathophysiology. It is important that the anesthetist give attention to all parameters so that oxygen supply is always equal to or greater than cardiac oxygen demand. In this manner, anesthesia may most safely be conducted for patients with compromised coronary circulation.