The effect of short stature, portal hypertension, and cholestasis on growth hormone resistance in children with liver disease

Chronic liver disease is associated with GH resistance, which is characterized by high circulating GH and low insulin-like growth factor I (IGF-I) concentrations. Standard GH replacement has no effect on serum IGF-I in pediatric liver disease. The aims were to examine whether GH resistance can be overcome by supraphysiological GH and to determine whether GH resistance worsens with the progression of liver disease. Thirty children, divided into five groups whose liver disease was at clinically different stages, were studied. They were given 0.2 IU/kg x day GH for 4 days and then 0.4 IU/kg x day for the next 4 days. Serum IGF-I and binding proteins (IGFBPs) were measured by immunoassay. IGF-I was lower in all study groups than in normal controls. IGF-I, IGFBP-3, and acid-labile subunit rose in response to GH. The magnitude of the response reflected nutritional status and liver dysfunction; in particular, portal hypertension was associated with a poor IGF-I response. There was no change in IGFBP-2. GH resistance begins early in the natural history of childhood liver disease and develops with the progression of liver disease, particularly with portal hypertension. It may be partially overcome by supraphysiological GH administration, but the effect becomes smaller with worsening liver disease.

Gene expression and serum levels of insulin-like growth factors (IGFs) and IGF-binding proteins in a case of non-islet cell tumour hypoglycaemia

We describe a case of non-islet cell tumour hypoglycaemia (NICTH) associated with a renal cell carcinoma. Serum insulin-like growth factors (IGFs) (including IGF-II E peptide), IGF-binding proteins (IGFBPs), insulin and C-peptide were measured before and after surgical removal of the tumour. IGFBPs were visualized by Western ligand blotting. Preoperatively 'big' IGF-II and IGFBP-2 levels were raised. IGF-I, IGFBP-1 and IGFBP-3 were low, while insulin, C-peptide and GH were undetectable. These changes were reversed by 2 days postoperatively. Protease assays showed little IGFBP-3 protease activity preoperatively. Preoperatively, neutral chromatography demonstrated most of the immunoassayable IGFBP-3 in a high molecular weight form with a small amount of IGF-II. Most of the IGF-II and big IGF-II eluted in lower molecular weight forms. Postoperative samples showed a shift in IGF-II which became increasingly associated with IGFBP-3 in both low and high molecular weight complexes. By Northern blotting, expression of all species of IGF-II mRNA in the tumour was 10-fold greater than in normal human liver. The tumour did not express IGFBP-1 or IGFBP-2. IGFBP-3 was expressed in small amounts, while the expression of IGFBP-4 was two-fold higher than in liver. In conclusion, we have confirmed high levels of big IGF-II and IGFBP-2 in NICTH, changes which are reversed postoperatively. The IGF-II is derived from the tumour which overexpresses these genes but IGFBP-2 probably arises from extratumour upregulation.

Clinical issues surrounding the use of terbutaline sulfate for preterm labor

beta-mimetics have been prescribed by physicians to arrest or prevent premature labor for more than 20 years. Although not approved by the Food and Drug Administration (FDA) for tocolytic use, terbutaline sulfate has been the most widely prescribed beta-mimetic in the United States. Recently, the role of terbutaline in the treatment and prevention of preterm labor has been questioned by the FDA. Because the off-label use of drugs is a formally accepted practice in medicine when scientific studies support such use, we reviewed the currently available clinical literature on terbutaline use in various routes of delivery: intravenous, oral, and subcutaneous via infusion pump. This review describes the clinical evidence that supports the safe and effective use of terbutaline as a tocolytic agent in certain patient populations. Practicing physicians should continue to have unrestricted use of terbutaline for tocolysis as one of the few remaining therapeutic options remaining in the fight against preterm birth.

Continuous core temperature monitoring of search and rescue divers during extreme conditions

OBJECTIVES

To study the feasibility of continuously monitoring core temperatures of search and rescue divers, to compare core temperature gradients occurring during warm and cold diving events, and to identify conditions under which divers are subjected to extreme temperatures.

METHODS

Between June 1994 and March 1995, emergency medical technicians (EMTs) from two midwestern dive teams volunteered to ingest an encapsulated temperature sensor developed for the National Aeronautics and Space Administration. The capsule monitored continuous core temperatures and transmitted the data to a recorder worn under the divers' dry suits.

RESULTS

Twenty male EMTs, mean age 34 years and mean body weight 184 pounds, were monitored during training. Nine dives were ice dives, with ice thickness averaging 9 inches, and mean ambient temperatures of 33 degrees F. Eleven dives were warm-water dives; average water temperature was 70 degrees F and mean ambient temperature was 74 degrees F. The average time spent in the dry suit was 95 minutes, and the mean total bottom time was 15 minutes. The ice divers showed a mean increase in core temperature of 1.0 degrees C, while the warm-water divers showed a mean increase of 1.2 degrees C. Divers experiencing the most extreme fluctuations were those in the role of safety diver, regardless of the season. Divers reported more subjective discomfort during ice dives than during warm-water dives.

CONCLUSIONS

Continuous monitoring of body temperature during the duration of dive operations is possible, but labor-intensive. Safety measures to protect divers from extreme core temperature fluctuations should focus on the safety diver as well as the active diver.

Can melatonin improve adaptation to night shift?

This study was undertaken to determine whether melatonin (N-acetyl-5 methoxytryptamine) is effective in helping emergency medical services (EMS) personnel who work rotating night shifts reset their biological clocks and minimize circadian rhythm disruption. A double-blinded, randomized, crossover study was performed using 22 volunteers. Participants were working a span of consecutive night (2300 to 0700 hours) shifts and received either a melatonin capsule (6 mg) or placebo to be taken before each of the consecutive day sleeps. Each participant completed a total of 4 spans of consecutive night shifts (2 melatonin, 2 placebo). Collected data included daily sleep diaries, quantification of alcohol/caffeine consumed, and drug side effects. Assessment of sleep quality, posttreatment mood, and workload ratings were measured daily by 10-cm visual analog scale (VAS). Analysis of sleep diaries found no significant difference (P > .05) between the two treatments with respect to mean sleep latency, duration, and efficiency, and subjectively rated sleep quality. Similarly, no significant benefits were noted between the median VAS scores for daily posttreatment mood or workload ratings. Adverse effects were rare; one patient taking melatonin reported a prolonged sedative effect. Despite recent interest in melatonin for treatment of circadian-based sleep disorders, no clinical benefits were noted in EMS personnel working rotating night shifts.

Use of the alveolar-arterial oxygen gradient in the assessment of acute pulmonary embolism

To evaluate the utility of the alveolar-arterial (A-a) oxygen gradient in the diagnosis of acute pulmonary embolism (PE), a retrospective analysis was done of consecutive emergency department patients who underwent pulmonary angiography for the presumed diagnosis of acute PE. Patients were categorized into two groups depending on the presence or absence of prior cardiopulmonary disease. Arterial blood gas samples were chosen for analysis only if obtained when the PE first was suspected clinically (before lung scans or angiograms) and the patient was breathing room air. A total of 152 patients met all study criteria; 59 patients (39%) had angiographically documented emboli. In comparison with the study patients in whom PE was excluded, there was no significant difference in mean PaO2 (64 v 67 mm Hg) or A-a gradient (39 v 36 mm Hg). Various combinations of the A-a gradient and blood gas levels failed to exclude PE in more than 35% of patients with no prior cardiovascular disease and in 25% of patients with prior cardiovascular disease. The A-a gradient did show a linear correlation with the severity of the PE, as assessed by the PaO2 (r = -0.87) and pulmonary artery mean pressure (r = 0.63). These results indicate that the A-a oxygen gradient, in combination with blood gas levels, may contribute to the formulation of a clinical assessment. However, these laboratory parameters are of insufficient discriminant value to permit exclusion of the diagnosis of PE.

Pubertal growth in IDDM is determined by HbA1c levels, sex, and bone age

OBJECTIVE

In cross-sectional studies of subjects with IDDM, the relationship between suboptimal pubertal growth, glycemic control, and abnormal insulin-like growth factor I (IGF-I) levels has proved difficult to define. The objective of this study was to examine these relationships in a longitudinal prospective study.

RESEARCH DESIGN AND METHODS

A total of 46 children (23 boys) were measured every 3 months, and their bone age was assessed annually. Blood samples were obtained for HbA1c, IGF-I, and C-peptide. Growth data were compared with national standards, and IGF-I data were compared with a parallel longitudinal study of normal schoolchildren. Data were analyzed as SD scores (mean +/- SD).

RESULTS

The onset of puberty was not delayed, although in the girls, bone age was advanced (bone age, 11.48 +/- 1.01 years vs. chronological age, 10.93 +/- 0.86 years [mean +/- SD]; P = 0.04). The timing of peak height velocity (PHV) was normal in both sexes, but the magnitude was reduced in girls (PHV SDS = -0.56 +/- 0.90, P < 0.02), and reductions in height SDS between diagnosis and final height were observed (P = 0.014). At PHV, IGF-I levels were reduced in both sexes, and there were no sex differences in HbA1c levels and insulin doses. IGF-I SDS correlated with insulin dose (r = 0.47, P = 0.004) but not with PHV SDS, whereas HbA1c correlated negatively with PHV SDS in both sexes (r = -0.35, P = 0.03). In a stepwise multiple regression analysis, the major determinants of PHV SDS were HbA1c (P = 0.04), sex (P = 0.0007), and bone age (P = 0.01).

CONCLUSIONS

We conclude that the magnitude of the pubertal growth spurt is related to HbA1c levels in both sexes, but it is reduced only in girls. This sexual dimorphism cannot be explained by differences in IGF-I levels and may relate to the bone age advance at the onset of puberty in the girls.

A double-blind comparison between oral pseudoephedrine and topical oxymetazoline in the prevention of barotrauma during air travel

To determine the efficacy of two decongestants (oral pseudoephedrine versus topical oxymetazoline) in the prevention of middle ear barotrauma during air travel, 150 adult volunteers with a history of ear pain during air travel were entered into a randomized, double-blind study conducted at two commercial airports. Each subject received 120 mg pseudoephedrine, oxymetazoline hydrochloride (0.05%), or a double placebo (capsule and nasal spray) administered 30 minutes before flight departure. After arrival at their final destinations, volunteers were asked to complete a questionnaire and return it by mail to investigators. Questions included the intensity and duration of otologic symptoms experienced while flying and possible drug side effects. A total of 124 subjects completed the study; 41 received 120 mg of pseudoephedrine, 42 received oxymetazoline nasal spray, and 41 received a double placebo (capsule and nasal spray). The three treatment groups were similar with regard to age, sex, medical history, and flight profile. Symptoms of barotrauma were reported by 34% of those receiving pseudoephedrine versus 71% of the control group, for a relative risk reduction of 52% (95% confidence interval [CI] 33% to 71%). In contrast, 64% of the oxymetazoline group reported symptoms of barotrauma, for a relative risk reduction of 10% (95% CI, 3% to 17%). These results suggest that treatment with 120 mg pseudoephedrine at least 30 minutes before flying appears to decrease the incidence of barotrauma. Oxymetazoline nasal spray is little more effective than placebo in reducing ear pain and discomfort associated with changing ambient pressures.