Circadian and ultradian rhythm and leptin pulsatility in adult GH deficiency: effects of GH replacement

Leptin contributes to the regulation of body weight in healthy individuals and is secreted by adipocytes in a diurnal pattern, with superimposed pulsatility. The circulating leptin concentration is increased in both normally obese and untreated adult GH deficiency, a syndrome characterized by increased adiposity. Leptin circadian rhythm is preserved in adult GH deficiency patients; however, an ultradian rhythm and pulsatility has previously not been reported. Alterations in plasma leptin concentration in obese individuals and adult GH deficiency patients after GH replacement have been attributed to changes in body fat mass. In our present study leptin circadian and ultradian rhythm, leptin pulsatility and its relationship with body fat mass were examined in 12 adult GH deficiency patients (6 men) before and 1 month after GH replacement. All subjects with adult GH deficiency had hypopituitarism subsequent to pituitary surgery and were stabilized on conventional pituitary hormone replacement. Plasma leptin was measured over 24 h at 30-min intervals, and changes in body composition were recorded using bioelectrical impedance. The 24-h mean leptin concentration decreased from 2.04 +/- 0.04 nmol/liter in untreated adult GH deficiency patients to 1.64 +/- 0.03 nmol/liter after 1 month of GH replacement (P < 0.0001). Before GH replacement, patients demonstrated a significant mean leptin circadian rhythm (P < 0.001), with a mesor of 2.05 +/- 0.03 nmol/liter and a superimposed ultradian frequency of 2.0 +/- 0.1 cycles/d. After GH replacement, the circadian rhythm was preserved (P < 0.001), but mesor decreased to 1.65 +/- 0.01 nmol/liter (P < 0.0001), and leptin ultradian frequency increased to 16.0 +/-0.2 cycles/d (P < 0.0001). Pulse analysis (ULTRA) revealed 3.1 +/- 0.9 pulses/24 h in untreated adult GH deficiency patients, which significantly increased to 9.9 +/- 2.2 pulses/24 h after 1 month of GH replacement (P < 0.001). There was no significant change in body mass index or body fat mass after 1 month of GH replacement. The body fat percentage significantly reduced from 36.5 +/- 2.8% to 35.5 +/- 2.7% after 1 month of GH replacement (P < 0.05). This change in body fat percentage was explained by a significant increase in lean body mass, from 56.2 +/- 2.8 kg at baseline to 57.4 +/- 2.7 kg after 1 month (P < 0.05). A significant correlation was observed between plasma leptin and body fat percentage at baseline and 1 month after GH replacement (both, r = 0.7; P < 0.01) in the absence of a significant correlation between leptin and body fat mass before and after GH replacement (P = 0.13 and P = 0.11, respectively). Thus, untreated adult GH deficiency is associated with elevated 24-h leptin concentration, preserved circadian rhythm, and decreased pulsatility. The secretory pattern is restored after GH replacement, with a significant reduction in the 24-h mean leptin concentration, maintenance of circadian rhythm, and increased pulsatility. This GH-induced change in the leptin secretory pattern precedes significant changes in body fat mass and may therefore be independent of changes in adipose tissue. Restoration of leptin pulsatility may be of clinical benefit, and our data could lead to novel approaches for leptin manipulation in the future.

[(99m)Tc]MAG(3)-mannosyl-dextran: a receptor-binding radiopharmaceutical for sentinel node detection

Technetium-99m-labeled benzoyl-mercaptoacetylglycylglycyl-glycine-mannosyl-dextran ([(99m)Tc]MAG(3)-mannosyl-dextran) is a receptor-binding radiotracer that binds to mannose-binding protein, a receptor expressed by recticuloendothelial tissue. This agent is composed of a 10.5-kilodalton molecule of dextran and multiple units of mannose, and benzoyl-mercaptoacetylglycylglycyl-glycine (BzMAG(3)). The tetraflorophenol-activated ester of BzMAG(3) and the imidate of thiomannose were used to covalently attach BzMAG(3) and mannose to an amino-terminated conjugate of dextran. This yielded a 19-kilodalton macromolecule consisting of 3 BzMAG(3) and 21 mannose units per dextran. Dynamic light scattering was used to measure a mean diameter of 5.5 nanometers for BzMAG(3)-mannosyl-dextran and 0.28 microns for filtered Tc-99m sulfur colloid. A preliminary sentinel node detection study employing right fore and hind footpad injections of [(99m)Tc]MAG(3)-mannosyl-dextran and left fore and hind footpad injections of filtered Tc-99m sulfur colloid demonstrated greater sentinel lymph node uptake by the receptor-binding agent.

A synthetic macromolecule for sentinel node detection: (99m)Tc-DTPA-mannosyl-dextran

We report the synthesis and preliminary biologic testing of a synthetic macromolecule, (99m)Tc-diethylenetriaminepentaacetic acid (DTPA)--mannosyl-dextran, for sentinel node detection.

METHODS

Synthesis started with a 2-step process that attaches a high density of amino-terminated leashes to a dextran backbone. Allyl-bromide was reacted with pharmaceutical-grade dextran to yield allyl-dextran. After diafiltration with water, filtration, and lyophilization, the product was reacted with aminoethanethiol and ammonium persulfate. The resulting amino-conjugated dextran was dialyzed, filtered, and lyophilized. The mixed anhydride method was used to attach DTPA; after dialysis, filtration, and lyophilization, 2-imino-2-methoxyethyl-1-D-mannose was used to attach the receptor substrate. The molecular diameter was measured by dynamic light scattering. Amino, mannose, and DTPA densities were measured by trinitrobenzene sulfonate assay, sulfuric acid/phenol assay, and inductively coupled plasma spectroscopy of gadolinium-DTPA-mannosyl-dextran, respectively. Receptor affinity was measured by Scatchard assay of rabbit liver. Axillary, popliteal, and iliac lymph nodes and each injection site were assayed for radioactivity at 1 and 3 h after injection of approximately 3.7 MBq (0.050 mL) (99m)Tc-DTPA-mannosyl-dextran (0.22 nmol) or filtered (99m)Tc-sulfur colloid into the foot pads. Four animals were studied at each time point.

RESULTS

DTPA-mannosyl-dextran had a molecular weight of 35,800 g/mol and a molecular diameter of 7.1 nm. The final amine, mannose, and DTPA densities were 23, 55, and 8 mol per dextran. Labeling yields were in excess of 98% and stable for 6 h. Specific activities of 74 x 10(6) GBq/mol were achieved. The equilibrium dissociation constant for binding to the mannose-terminated glycoprotein receptor was 0.12 +/- 0.07 nmol/L. The popliteal extraction at both 1 h and 3 h was significantly (P < 0.05) higher for (99m)Tc-DTPA-mannosyl-dextran (90.1% +/- 10.7% and 97.7% +/- 2.0%, respectively) than for filtered (99m)Tc-sulfur colloid (78.8 +/- 6.5 and 67.4% +/- 26.8%, respectively). (99m)Tc-DTPA-mannosyl-dextran exhibited significantly faster injection site clearance than did filtered (99m)Tc-sulfur colloid. The (99m)Tc-DTPA-mannosyl-dextran percentage injected dose (%ID) for the front and rear paws was 52.6 +/- 10.5 and 52.3 +/- 8.0 at 1 h and 45.7 +/- 8.5 and 43.6 +/- 8.2 at 3 h after administration. The filtered (99m)Tc-sulfur colloid %ID for the front and rear paws was 70.4 +/- 11.0 and 66.3 +/- 15.1 at 1 h and 55.5 +/- 7.8 and 66.9 +/- 8.5 at 3 h. Lymph node accumulation of each agent at either 1 or 3 h was not significantly different.

CONCLUSION

(99m)Tc-DTPA-mannosyl-dextran is a receptor-based sentinel node radiotracer that exhibits the desired properties of rapid injection site clearance and low distal node accumulation. This molecule is the first member of a new class of diagnostic agents based on a macromolecular backbone with a high density of sites for the attachment of substrates and imaging reporters.

Preliminary results of a pilot study investigating the potential of salivary cortisol measurements to detect occult adrenal suppression secondary to steroid nose drops

Adrenocortical suppression is a well-known risk of systemic steroids, but is thought less likely to occur with topical intranasal corticosteroids. However, the UK Committee on the Safety of Medicines (UKCSM) has expressed concern about the possibility of this complication. We assessed the prevalence of adrenal suppression in patients with rhinitis using intranasal beclomethasone and betamethasone; and the potential value of salivary cortisol as a tool for detecting this complication. Sixty-six patients (38 men: 28 women; mean age 49.6[SD 16.0] years) were prospectively screened for adrenal insufficiency using clinical assessment and salivary cortisol measurements. Abnormalities at this initial screening were confirmed with a Short Synacthen Test (SST). No patient was clinically Cushingoid. All 22 beclomethasone users had normal salivary cortisols. Eleven (25%) of 44 patients using betamethasone had subnormal salivary cortisol levels (mean morning cortisol 2.8[SD 0.9]nmol/l) suggesting adrenal suppression, which was confirmed by an impaired SST in each case. The positive predictive value of salivary cortisol measurements was 100%. Only patients with abnormal salivary cortisols had a SST, so no comment can be made about sensitivity/specificity. Topical betamethasone may produce occult adrenal insufficiency and assessment of adrenal function is recommended in these patients. Measurement of salivary cortisol is a useful, non-invasive and economical test for monitoring patients using intranasal corticosteroids.

Differences in circulating concentrations of total, free and bound leptin relate to gender and body composition in adult humans

We describe a radioimmunoassay (RIA) for total leptin and a gel filtration procedure for the separation of free and bound leptin in human serum. The RIA, based on a locally prepared antibody, has a minimum detection limit of 0.9 ng/mL, a working range (CV < 10%) of 2.5-50 ng/mL, inter-assay precision of 10.2, 7.2 and 8.9%CV at 7.9, 15.4 and 30.0 ng/mL, respectively, 94% recovery of exogenous leptin (range 81.1-120.6%), exhibited parallelism and demonstrated no significant cross-reactivity or interferences. A difference plot of results from this method and those from a commercially available kit (Linco Research) demonstrated satisfactory agreement up to concentrations of 50 ng/mL total leptin, with no significant bias. A gender-dependent correlation was obtained between body mass index (BMI) and total leptin (r = 0.91, P<0.001, n = 75 for men; r = 0.79, P<0.001, n = 72 for women), with women having higher leptin concentrations than men for any given BMI. Gel filtration studies (inter-assay precision: 4.7%CV, n = 18) demonstrated that a variable fraction (between 10% and 40%) of total leptin in serum was bound with high affinity (Keq = 1.0-1.45 x 10(9) L/mol) to a non-albumin, non-lipid macromolecule. Binding affinities were found to be similar irrespective of gender or fat mass. A significant positive correlation between free or bound leptin concentrations and BMI was obtained for both men and women (r = 0.87-0.94); free and bound leptin concentrations were also significantly higher in women (P<0.01) than in men for any given BMI, and higher in obese (P<0.01) than in lean individuals. We conclude that leptin 'resistance' associated with obesity cannot be accounted for by reduced free leptin concentrations in serum and that the methods described are suitable for the investigation of total, free and bound leptin for both clinical and research purposes.

The co-ordinated cytokine/hormone response to acute injury incorporates leptin

Recent studies have implicated leptin as a "stress" hormone and highlighted its association with increases in inflammatory cytokines, C-reactive protein and cortisol. In order to investigate the exact temporal leptin response to stress we undertook a detailed longitudinal study of circulating leptin concentrations during the well defined surgical injury of cholecystectomy. Circulating concentrations of cortisol, free fatty acids, leptin and C-reactive protein were measured at 3, 6, 9, 12, 18, 24, 48 and 72 h from the start of surgery in nine patients. There was a significant correlation between baseline concentrations of leptin and BMI (r=0. 893, P<0.001). Over the 72 h from the start of surgery there were significant (P<0.05) increases in the concentrations of all analytes (peak median concentrations); cortisol (6 h), free fatty acids (9 h), leptin (18 h) and C-reactive protein (48 h). Interestingly the timing of the leptin peak at approximately 18 h after an acute inflammatory stimulus is exactly the same as previously reported for interleukin 6. These data support the suggestion that the relationship between cortisol and leptin mirrors that of cortisol and another cytokine, interleukin 6, i.e. stimulatory in acute and suppressive in chronic situations. They also imply a physiological role for leptin in acute injury.

Ras activation in human breast cancer

Genetic ras mutations are infrequent in breast cancer but Ras may be pathologically activated in breast cancer by overexpression of growth factor receptors which signal through Ras. Using a highly sensitive, coupled enzymatic assay, we measured Ras activation in 20 breast cancers, two fibroadenomas, and seven normal breast samples. Ras was highly activated compared to benign tissue in 11 of the 20 cancers; 7 of these 11 cancers expressed both the epidermal growth factor (EGF) and ErbB-2/neu/HER-2 receptors with the remaining four cancers with high Ras activation expressing one of these two receptors. In the other nine cancers, Ras activation was similar to that observed in benign breast tissue with none of these cancers expressing the EGF receptor while one expressed the ErbB-2 receptor. None of the cancers tested had an activating K-ras mutation nor did any of the cancers express a truncated EGF receptor or the c-FMS receptor. The activity of mitogen-activated protein (MAP) kinase was high in the cancers, and reflected the degree of Ras activation. In cultured mammary tumor cell lines, we showed that Ras activation was ligand dependent in cells overexpressing the ErbB-2 receptor. Thus, Ras was abnormally activated in breast cancers overexpressing the EGF and/or ErbB-2 receptors indicating there are sufficient ligands in vivo to activate these receptors, and this work provides a basis for new target-based treatments of this disease.

Isolation and characterization of polyadenylation complexes assembled in vitro

We developed a two-step purification of mammalian polyadenylation complexes assembled in vitro. Biotinylated pre-mRNAs containing viral or immunoglobulin poly(A) sites were incubated with nuclear extracts prepared from mouse myeloma cells under conditions permissive for in vitro cleavage and polyadenylation and the mixture was fractionated by gel filtration; complexes containing biotinylated pre-mRNA and bound proteins were affinity purified on avidin-agarose resin. Western analysis of known components of the polyadenylation complex demonstrated copurification of polyadenylation factors with poly(A) site-containing RNA but not with control RNA substrates containing either no polyadenylation signals or a point mutation of the AAUAAA polyadenylation signal. Polyadenylation complexes that were assembled on exogenous RNA eluted from the Sephacryl column in fractions consistent with their size range extending from 2 to 4 x 10(6) Mr. Complexes endogenous to the extract were of approximately the same apparent size, but more heterogeneous in distribution. This method can be used to study polyadenylation/cleavage complexes that may form upon a number of different RNA sequences, an important step towards defining which factors might differentially associate with specific RNAs.

Phenotypic variability and origins of mutations in the gene encoding 3beta-hydroxysteroid dehydrogenase type II

Mutations in HSD3B2, the gene for 3beta-hydroxysteroid dehydrogenase type II (3beta-HSD II) have been detected and activities analysed through the in vitro expression of mutant cDNAs. Two full sibs with male pseudohermaphroditism were found to be double heterozygotes: N100S/266DeltaA. This genotype leads to the most profound loss of 3beta-HSD II enzyme activity (1.3% of normal) described to date in cases without severe salt-loss. One sib (N100S/266DeltaA) is the first reported male case of type II deficiency affected with premature adrenarche. Three apparently independent kindreds had propositi affected with the HSD3B2 mutation A82T/A82T, which is associated with a non salt-losing phenotype with variable expressivity in females. These three families had the same extended HSD3B haplotype and are likely to have inherited the same ancestral mutation. The significance of this finding is discussed in the light of the presence of A82T mutation at a homologous position in pseudogene varphi5 that is present in the HSD3B cluster.

Cloning, expression, and physical mapping of the 3beta-hydroxysteroid dehydrogenase gene cluster (HSD3BP1-HSD3BP5) in human

Seven members of the human 3beta-hydroxysteroid dehydrogenase (3beta-HSD) gene family (HGMW-approved symbols HSD3BP1-HSD3BP5) have been cloned and physically mapped. HSD3B1 and 2 express 3beta-HSD enzymes; HSD3Bpsi1-5 are unprocessed pseudogenes that are closely related to HSD3B1 and 2 but contain no corresponding open reading frames. mRNA is expressed from psi4 and psi5 in several tissues, but with altered splice sites that disrupt reading frames. A 0.5-Mb contig of 3 yeast artificial chromosome and 32 bacterial artificial chromosome genomic clones contained no additional members of the gene family. The seven genes and pseudogenes mapped within 230 kb in the order HSD3Bpsi5-psi4-psi3-HSD3B1-psi1-psi2 -HSD3B2. HSD3B1 and 2 are in direct repeat, 100 kb apart. Six HSD3B2 mutations involve substitutions that are present in several of the pseudogenes. In four cases, mutations arose in CpG sites that are conserved within the gene cluster. The tendency for CpG sites to mutate by transition provides an adequate explanation for these HSD3B2 mutations, which are unlikely to be due to recombination or conversion within the gene family.

Apparent cortisone reductase deficiency: a functional defect in 11beta-hydroxysteroid dehydrogenase type 1

A 36-yr-old woman was referred to the endocrine clinic for investigation of oligomenorrhea, hirsutism, and acne. She was plethoric and overweight with central fat distribution. Plasma cortisol was normal, but her adrenal glands were enlarged (CT scan). Urinary tetrahydrocortisone excretion rate was consistently high, raising the possibility of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) deficiency. In addition, 5beta- reduction of cortisol and cortisone was markedly enhanced. The levels of all cortisol metabolites were suppressed normally with dexamethasone, but conversion of oral cortisone acetate to plasma cortisol was delayed and subnormal compared with that of healthy volunteers. This was accompanied by a larger than normal increase in plasma cortisone concentration. Thus, the defect appears to be in 11beta-HSD1 activity and not in 5beta-reductase activity. Three close relatives of the subject showed no comparable abnormalities, and analysis of the coding region and exon/intron boundaries of the 11beta-HSD1 gene of the case revealed no differences from the consensus sequence. The defect may lie outside the coding region. Alternatively, some other inherited or acquired defect may lead to inhibition of this enzyme system.

Two distinct forms of the 64,000 Mr protein of the cleavage stimulation factor are expressed in mouse male germ cells

Polyadenylation in male germ cells differs from that in somatic cells. Many germ cell mRNAs do not contain the canonical AAUAAA in their 3' ends but are efficiently polyadenylated. To determine whether the 64,000 Mr protein of the cleavage stimulation factor (CstF-64) is altered in male germ cells, we examined its expression in mouse testis. In addition to the 64,000 Mr form, we found a related approximately 70,000 Mr protein that is abundant in testis, at low levels in brain, and undetectable in all other tissues examined. Expression of the approximately 70,000 Mr CstF-64 was limited to meiotic spermatocytes and postmeiotic spermatids in testis. In contrast, the 64,000 Mr form was absent from spermatocytes, suggesting that the testis-specific CstF-64 might control expression of meiosis-specific genes. To determine why the 64,000 Mr CstF-64 is not expressed in spermatocytes, we mapped its chromosomal location to the X chromosome in both mouse and human. CstF-64 may, therefore, be absent in spermatocytes because the X chromosome is inactivated during male meiosis. By extension, the testis-specific CstF-64 may be expressed from an autosomal homolog of the X chromosomal gene.

Effect of weight loss and the inflammatory response on leptin concentrations in gastrointestinal cancer patients

Animal research suggests that leptin may have an important role in the regulation of energy balance. The role of leptin in the progressive involuntary weight loss associated with cancer in humans is of considerable interest. However, such studies are limited. In this study, we compared circulating leptin concentrations in gastrointestinal cancer patients and weight loss (n = 27) with those of healthy subjects (n = 27). The effect of the presence of an inflammatory response on leptin concentrations was also examined. There were significantly lower leptin concentrations in male (median, 2.4 microg/liter; range, <0.5-6.0 microg/liter) and female (median, 3.4 microg/liter; range, <0.5-9.8 microg/liter) cancer patients than there were in male (median, 6.5 microg/liter; range, 3.1-10.9 microg/liter) and female (median, 18.7 microg/liter; range, 8.0-31.5 mcirog/liter) healthy subjects (P < 0.001). However, the leptin concentrations in both patients and normal subjects were related to the predicted percentage of body fat (r = 0.731; P < 0.001). Circulating leptin concentrations in the cancer patients were not altered by the presence of an inflammatory response. These results suggest that cancer anorexia/cachexia is not due to a simple dysregulation of leptin production.

Time-of-Flight Optical Ranging System Based on Time-Correlated Single-Photon Counting

The design and implementation of a prototype time-of-flight optical ranging system based on the time-correlated single-photon-counting technique are described. The sensor is characterized in terms of its longitudinal and transverse spatial resolution, single-point measurement time, and long-term stability. The system has been operated at stand-off distances of 0.5-5 m, has a depth repeatability of <30 mum, and has a lateral spatial resolution of <500 mum.

Serum concentrations of laminin P1 and aminoterminal propeptide of type III procollagen in sickle cell disease

We determined serum levels of laminin and aminoterminal propeptide of type III procollagen (PIIINP) in 20 patients with sickle cell hemoglobinopathies. Elevated levels of soluble laminin and PIIINP were observed in the patients--1.5 +/- 0.3 U/ml (mean +/- SD) (range 1.1-1.9 U/ml) and 0.90 +/- 0.2 U/ml (range 0.6-1.4 U/ml), respectively, compared to normal controls, 1.3 +/- 0.1 U/ml (range 1.2-1.4 U/ml) for laminin and 0.7 +/- 0.1 U/ml (range 0.6-0.9 U/ml) for PIIINP. The serum laminin and PIIINP were significantly elevated (p < 0.02 and p < 0.001, respectively, in patients with sickle cell hemoglobinopathies). There was no correlation between serum laminin and PIIINP levels in the patient group. The study indicates that aminoterminal propeptide of type III procollagen and laminin can be utilized as valuable non-invasive markers of possible alterations in extracellular matrix in bone marrow, spleen, kidney or other tissues in sickle cell hemoglobinopathies.

Neutralase reverses the anti-coagulant but not the anti-thrombotic activity of heparin in a rabbit model of venous thrombosis

Neutralase (heparinase I; E.C. 4.2.2.7) is a heparin-degrading enzyme undergoing clinical evaluation as an alternative to protamine for reversing the anticoagulant effects of heparin in coronary bypass surgery. The objective of this study was to assess the relative effects of Neutralase and protamine on reversal of heparin-dependent elevations in coagulation parameters and inhibition of clot formation in a rabbit vena caval stasis model. Rabbits were treated with saline or heparin (300 U/kg) for 10 minutes, followed by saline, protamine (2.6 mg/kg), or Neutralase (10 or 30 microg/kg, representing 1.23 IU/kg and 3.69 IU/kg, respectively). Twenty minutes later, venous stasis was induced, and vena caval clots were excised, weighed, and characterized. Coagulation parameters [activated partial thromboplastin time (aPTT) and thrombin clotting time (TCT)] and antiFactor IIa and Xa levels were measured throughout the protocol. Both protamine and Neutralase reversed heparin-mediated increases in aPTT (>300 seconds to 26-35 seconds) and TCT (>300 seconds to 29-56 seconds) to values that were not different from saline-treated, nonheparinized animals. Thrombus weight in the nonheparinized saline group was 62+/-7 mg; heparin-treated animals had no detectable clots. Protamine reversal of heparin was associated with clot formation (89+/-20 mg) while Neutralase reversal was not (no clots). Heparin-induced increases in antiFactor IIa activity were reversed similarly by protamine and Neutralase (from 4.3-8.8 U/ml to 0.2-0.3 U/ml) while antiFactor Xa activity was differentially reversed (from 3.9-5.9 U/ml to 0.7-1.3 U/ml Neutralase; 5.5 U/ml to 0.02 U/ml protamine). These results are consistent with a hypothesis that Neutralase cleaves heparin into fragments, which are devoid of antiFactor IIa activity that retain modest antiFactor Xa activity, resulting in reversal of anticoagulant, but not antithrombotic, heparin activity. This property of Neutralase may be beneficial in reducing post-surgical thrombotic events after reversal of heparin.

Leptin levels in pregnancy: marker for fat accumulation and mobilization?

BACKGROUND

Leptin, an adipose tissue-derived signalling factor encoded by the obese gene has been shown to be present as a 16-kDa protein in the blood of mice and humans. Resistance to leptin occurs in human obesity. Leptin has also been shown to associate with plasma insulin concentrations and there is currently considerable debate about the potential link between insulin resistance and resistance to leptin. In non-pregnant individuals, circulating leptin concentrations associate strongly with both total body fat mass and body mass index (BMI). In normal human pregnancy, the maternal fat stores increase to a peak in the late second trimester, before declining towards term as fat stores are mobilized to support the rapidly growing fetus. Insulin resistance increases during late pregnancy and is believed to be further enhanced in pregnancies complicated by pre-eclampsia. The aim of this study was to examine if leptin levels were altered in pregnancy and, if so, whether the pattern of change in circulating leptin related to previously established changes in fasting insulin concentrations or fat mass.

METHODS

We measured third trimester plasma leptin concentrations in 12 uncomplicated pregnant women, nine women with pre-eclampsia matched for age and booking BMI, and 18 non-pregnant women similarly matched. We also examined the longitudinal course of leptin concentrations occurring throughout gestation (from 10 weeks gestation and at five week intervals thereafter), in five normal pregnancies and two women with gestational-onset diabetes.

RESULTS

Leptin concentrations were significantly higher in the normal pregnant women (37.1 microg/L, [15.4-117.0], geometric mean, [range]; p=0.049), and women with pre-eclampsia (45.3 microg/L, [21.3-98.4]; p=0.001), than in non-pregnant controls (17.85 microg/L, [1.3-36.5]), however, there was no significant difference between uncomplicated and pre-eclamptic pregnancies (p=0.22). On examination of the longitudinal course of leptin concentrations occurring throughout gestation, in all seven women plasma leptin concentrations initially increased relative to booking (10 weeks) concentrations, but did so by varying amounts (ranging between 30-233%). Significantly, however, in all seven women plasma leptin concentrations peaked at around 20-30 weeks of gestation before declining towards term.

CONCLUSION

On the basis of these observations, we postulate that plasma leptin levels increase significantly in human pregnancies and that the pattern of change in circulating leptin parallels the process of fat accumulation and mobilization.

Type I collagen as a marker of bone metabolism in sickle cell hemoglobinopathies

Avascular necrosis of the skeletal system is a complication of sickle cell hemoglobinopathies. Type I collagen, which is synthesized by osteoblasts, comprises about 90% of the total organic matrix of bone. This preliminary study of skeletal changes in sickle cell hemoglobinopathies measured type I collagen formation and degradation using specific radioimmunoassays to determine the plasma concentrations of carboxyterminal propeptide of type I procollagen (PICP) and carboxyterminal pyridinoline cross-linked telopeptide of type I collagen (ICTP), respectively. Plasma ICTP concentrations were increased significantly in sickle cell patients with no clinical or radiologic symptoms of bone complications than in controls. Mean plasma ICTP concentration was moderately high in all patients. Plasma PICP levels did not differ significantly between patients and controls. This preliminary results indicate that measurements of plasma ICTP might be helpful in predicting bone changes in sickle cell hemoglobinopathies and also useful in the early detection of skeletal complications of the disease.

A practical guide to preemption for self-insured plans

This article discusses the circumstances under which federal law preempts state law regulating self-insured plans. In particular, the author describes four recent cases in which ERISA preemption was challenged, including relevant issues of debate and conclusions. The article points out that the decisions that result from such cases are contributing to the guidelines that states are developing to regulate ERISA plans.