Effect of online diabetes training for hospitalists on inpatient glycaemia.

AIM: An online diabetes course for medical residents led to lower patient blood glucose, but also increased hypoglycaemia despite improved trainee confidence and knowledge. Based on these findings, we determined whether an optimized educational intervention delivered to hospitalists (corresponding to an Acute Physician or Specialist in Acute Hospital Medicine in the UK) improved inpatient glycaemia without concomitant hypoglycaemia. METHODS: All 22 hospitalists at an academic medical centre were asked to participate in an online curriculum on the management of inpatient dysglycaemia in autumn 2009 and a refresher course in spring 2010. RESULTS: All hospitalists completed the initial intervention. Median event blood glucose decreased from 9.3 mmol/l (168 mg/dl) pre-intervention to 7.8 mmol/l (141 mg/dl) post-intervention and 8.5 mmol/l (153 mg/dl) post-refresher (P < 0.001 for both). Hospitalizations categorized as hyperglycaemia decreased from 83.3 to 55.6% (P = 0.014), with a trend towards euglycaemia (10-28.9%, P = 0.08) and no change in hypoglycaemia. Hyperglycaemic patient-days decreased from 72.0 to 57.3% (P = 0.004), with greater target glycaemia (27.3-39.4%, P = 0.016) and no change in hypoglycaemia. CONCLUSIONS: An optimized online educational intervention delivered to hospitalists yielded significant improvements in inpatient glycaemia without increased hypoglycaemia.

The effect of leptin administration on mammary tumor growth in diabetic mice.

Obesity is associated with hyperleptinemia and this has led to the suggestion that leptin maybe a factor in cancer progression. To study the effect of leptin on cancer progression we used a mouse model of diabetes that was shown to enhance tumor progression and thereby determine if leptin affects cancer progression despite improvements in metabolic status. Mammary tumors were allowed to develop in male and female mice following orthotopic injection of cells expressing oncogenes. After 2 weeks leptin was administered to the mice using Alzet pumps. In these mice leptin failed to stimulate tumor progression; indeed, in those studies where glucose tolerance improved tumor growth was actually inhibited. Thus, the possibility exists that the effect of leptin on tumor progression maybe opposed by improvements in metabolism.

Growth hormone treatment induces mammary gland hyperplasia in aging primates.

The decline of growth hormone (GH) and insulin-like growth factor I (IGF-I) production during aging has been likened to the decrease in gonadal steroids in menopause. The repletion of GH/IGF-I levels in aging individuals is suggested to restore the lean tissue anabolism characteristic of youth. In addition to anabolic effects on musculo-skeletal tissues, GH also stimulates mammary glandular growth in some species, although its effects on primate mammary growth remain unclear. Some clinical observations implicate GH in human mammary growth, for example, gynecomastia occurs in some children treated with GH (ref. 6), and tall stature and acromegaly are associated with an increased incidence of breast cancer. To investigate the effects of GH/IGF-I augmentation on mammary tissue in a model relevant to aging humans, we treated aged female rhesus monkeys with GH, IGF-I, GH + IGF-I or saline diluent for 7 weeks. IGF-I treatment was associated with a twofold increase, GH with a three- to fourfold increase, and GH + IGF-I with a four'-to fivefold increase in mammary glandular size and epithelial proliferation index. These mitogenic effects were directly correlated with circulating GH and IGF-I levels, suggesting that either GH or its downstream effector IGF-I stimulates primate mammary epithelial proliferation.

Serum insulin-like growth factor I regulates brain amyloid-beta levels.

Levels of insulin-like growth factor I (IGF-I), a neuroprotective hormone, decrease in serum during aging, whereas amyloid-beta (Abeta), which is involved in the pathogenesis of Alzheimer disease, accumulates in the brain. High brain Abeta levels are found at an early age in mutant mice with low circulating IGF-I, and Abeta burden can be reduced in aging rats by increasing serum IGF-I. This opposing relationship between serum IGF-I and brain Abeta levels reflects the ability of IGF-I to induce clearance of brain Abeta, probably by enhancing transport of Abeta carrier proteins such as albumin and transthyretin into the brain. This effect is antagonized by tumor necrosis factor-alpha, a pro-inflammatory cytokine putatively involved in dementia and aging. Because IGF-I treatment of mice overexpressing mutant amyloid markedly reduces their brain Abeta burden, we consider that circulating IGF-I is a physiological regulator of brain amyloid levels with therapeutic potential.

MKR mice have increased dynamic glucose disposal despite metabolic inflexibility, and hepatic and peripheral insulin insensitivity.

AIMS/HYPOTHESIS: Recent work has shown that there can be significant differences when glucose disposal is assessed for high-fat induced insulin resistance by static clamp methods vs dynamic assessment during a stable isotope i.p. glucose tolerance test. MKR mice, though lean, have severe insulin resistance and decreased muscle fatty acid oxidation. Our goal was to assess dynamic vs static glucose disposal in MKR mice, and to correlate glucose disposal and muscle-adipose-liver flux interactions with metabolic flexibility (indirect calorimetry) and muscle characteristics. METHODS: Stable isotope flux phenotyping was performed using [6,6-(2)H(2)]glucose, [U-(13)C(6)]glucose and [2-(13)C]glycerol. Muscle triacylglycerol (TAG) and diacylglycerol (DAG) content was assessed by thin layer chromatography, and histological determination of fibre type and cytochrome c activity performed. Metabolic flexibility was assessed by indirect calorimetry. RESULTS: Indirect calorimetry showed that MKR mice used more glucose than FVB/N mice during fasting (respiratory exchange ratio [RER] 0.88 vs 0.77, respectively). Compared with FVB/N mice, MKR mice had faster dynamic glucose disposal, despite increased whole-muscle DAG and TAG, and similar hepatic glucose production with higher fasting insulin and unchanged basal glucose. Fed MKR muscle had more glycogen, and increased levels of GLUT1 and GLUT4 than FVB/N muscle. Histology indicated that MKR soleus had mildly decreased cytochrome c activity overall and more type II (glycolytic) fibres compared with that in FVB/N mice. CONCLUSIONS/INTERPRETATION: MKR muscle adapts to using glucose, with more type II fibres present in red muscle. Fasting RER is elevated and glucose disposal during an i.p. glucose tolerance test is accelerated despite increased muscle DAG and TAG. Metabolic inflexibility may result from the compensatory use of fuel that can be best utilised for energy requirements; static vs dynamic glucose disposal assessments may measure complementary aspects of metabolic flexibility and insulin sensitivity.

Apolipoprotein E deficiency abrogates insulin resistance in a mouse model of type 2 diabetes mellitus.

AIMS/HYPOTHESIS: Although it is known that lipid metabolism plays a role in insulin resistance in type 2 diabetes and in obesity, the mechanism is still largely unknown. Apolipoprotein E (ApoE) regulates plasma lipid levels and also plays a role in the uptake of lipids into various tissues. To investigate whether the suppression of whole-particle lipoprotein uptake into tissues affects insulin responsiveness and the diabetic condition, we examined the effect of an ApoE (also known as Apoe) gene deletion in MKR mice, a mouse model of type 2 diabetes. METHODS: ApoE ( -/- ), MKR, ApoE ( -/- )/MKR and control mice were placed on a high-fat, high-cholesterol diet for 16 weeks. Glucose tolerance, serum insulin, blood glucose, insulin tolerance, tissue triacylglycerol content and atherosclerotic lesions were assessed. RESULTS: ApoE ( -/- )/MKR and ApoE ( -/- ) mice showed significantly improved blood glucose, glucose tolerance and insulin sensitivity. Reduced triacylglycerol content in liver and reduced fat accumulation in liver and adipose tissue were found in ApoE ( -/- )/MKR and ApoE ( -/- ) mice compared with control and MKR mice. ApoE ( -/- ) and ApoE ( -/- )/MKR mice demonstrated similarly large atherosclerotic lesions, whereas MKR and control mice had small atherosclerotic lesions. CONCLUSIONS/INTERPRETATION: We demonstrated that ApoE deficiency abrogates insulin resistance in a mouse model of type 2 diabetes, suggesting that lipid accumulation in tissue is a major cause of insulin resistance in this mouse model.

Insulin-like growth factor-I protects cells from ER stress-induced apoptosis via enhancement of the adaptive capacity of endoplasmic reticulum.

Disruption of endoplasmic reticulum (ER) homeostasis causes accumulation of unfolded and misfolded proteins in the ER, triggering the ER stress response, which can eventually lead to apoptosis when ER dysfunction is severe or prolonged. Here we demonstrate that human MCF-7 breast cancer cells, as well as murine NIH/3T3 fibroblasts, are rescued from ER stress-initiated apoptosis by insulin-like growth factor-I (IGF-I). IGF-I significantly augments the adaptive capacity of the ER by enhancing compensatory mechanisms such as the IRE1 alpha-, PERK- and ATF6-mediated arms of ER stress signalling. During ER stress, IGF-I stimulates translational recovery and induces expression of the key molecular chaperone protein Grp78/BiP, thereby enhancing the folding capacity of the ER and promoting recovery from ER stress. We also demonstrate that the antiapoptotic activity of IGF-I during ER stress may be mediated by a novel, as yet unidentified, signalling pathway(s). Application of signal transduction inhibitors of MEK (U1026), PI3K (LY294002 and wortmannin), JNK (SP600125), p38 (SB203580), protein kinases A and C (H-89 and staurosporine) and STAT3 (Stattic) does not prevent IGF-I-mediated protection from ER stress-induced apoptosis. Taken together, these data demonstrate that IGF-I protects against ER stress-induced apoptosis by increasing adaptive mechanisms through enhancement of ER stress-signalling pathways, thereby restoring ER homeostasis and preventing apoptosis.

Obesity and type 2 diabetes are associated with an increased risk of developing cancer and a worse prognosis; epidemiological and mechanistic evidence.

Both obesity and Type 2 diabetes are independently associated with an increased risk of developing cancer and an increased mortality. The etiology is yet to be determined but insulin resistance and hyperinsulinemia maybe important factors. Hyperglycemia, hyperlipidemia and inflammatory cytokines in addition to the insulin-like growth factors are also possible factors involved in the process.

Insulin resistance and the metabolic syndrome.

The metabolic syndrome is a constellation of risk factors including glucose dysregulation, central obesity, dyslipidemia, and hypertension. There are multiple definitions that have been described by various health organizations. However, we do know that insulin resistance plays a major role as the underlying cause for the development and potentiation of the metabolic syndrome. At present, it is unclear if the diagnosis of metabolic syndrome is greater than the sum of its parts. However, the presence of more than one of the associated risk factors should indicate that a patient is at increased risk for developing diabetes, cardiovascular disease and death. Thus, the primary care physician should aggressively treat the metabolic risk factors in their patients to prevent the onset and progression to more severe disease.

Regulation by fasting of rat insulin-like growth factor I and its receptor. Effects on gene expression and binding.

We have examined, in liver and extrahepatic tissues, the effects of fasting on total insulin-like growth factor I (IGF-I) mRNA levels, on levels of different IGF-I mRNAs generated by alternative splicing of the primary IGF-I transcript, and on IGF-I receptor binding and mRNA levels. A 48-h fast decreased total IGF-I mRNA levels by approximately 80% in lung and liver, approximately 60% in kidney and muscle, and only approximately 30-40% in stomach, brain, and testes. In heart, IGF-I mRNA levels did not change. The levels of the different splicing variants, however, were essentially coordinately regulated within a given tissue. Specific 125I-IGF-I binding in lung, testes, stomach, kidney, and heart was increased by fasting by approximately 30-100%, whereas in brain 125I-IGF-I binding did not change in response to fasting. In tissues in which fasting increased IGF-I receptor number, receptor mRNA levels increased approximately 1.6- to 2.5-fold, whereas when IGF-I receptor number was unchanged in response to fasting, receptor mRNA levels did not change. These data demonstrate that the change in IGF-I and IGF-I receptor mRNA levels during fasting is quantitatively different in different tissues and suggest that regulation of IGF-I and IGF-I receptor gene expression by fasting is discoordinate.

Targeted overexpression of IGF-I evokes distinct patterns of organ remodeling in smooth muscle cell tissue beds of transgenic mice.

Smooth muscle cells (SMC) of the vascular wall, bladder, myometrium, and gastrointestinal and respiratory tracts retain the ability to proliferate postnatally, which enables adaptive responses to injury, hormonal, or mechanical stimulation. SMC growth is regulated by a number of mesenchymal growth factors, including insulin-like growth factor I (IGF-I). To explore the function of IGF-I on SMC in vivo, the mouse SMC alpha-actin promoter fragment SMP8 (-1074 bp, 63 bp of 5'UT and 2.5 kb of intron 1) was cloned upstream of rat IGF-I cDNA, and the fusion gene microinjected to fertilized eggs of the FVB-N mouse strain. Mating of hemizygous mice with controls produced about 50% transgenic offspring, with equal sex distribution. Transgenic IGF-I mRNA expression was confined to SMC-containing tissues, with the following hierarchy: bladder > stomach > aorta = uterus > intestine. There was no transgene expression in skeletal muscle, heart, or liver. Radioimmunoassayable IGF-I content was increased by 3.5- to 4-fold in aorta, and by almost 10-fold in bladder of transgenic mice at 5 and 10 wk, with no change in plasma IGF-I levels. Wet weight of bladder, stomach, intestine, uterus, and aorta was selectively increased, with no change in total body or carcass weight of transgenic animals. In situ hybridization showed that transgene expression was exquisitely targeted to the smooth muscle layers of the arteries, veins, bladder, ureter, stomach, intestine, and uterus. Paracrine overproduction of IGF-I resulted in hyperplasia of the muscular layers of these tissues, manifesting in remarkably different phenotypes in the various SMC beds. Whereas the muscular layer of the bladder and stomach exhibited a concentric thickening, the SMC of the intestine and uterus grew in a longitudinal fashion, resulting in a marked lengthening of the small bowel and of the uterine horns. This report describes the first successful targeting of expression of any functional protein capable of modifying the phenotype of SMC in transgenic mice. IGF-I stimulates SMC hyperplasia, leading to distinct patterns of organ remodeling in the different tissue environments.

Involution of the lactating mammary gland is inhibited by the IGF system in a transgenic mouse model.

Development of the mammary gland during puberty, pregnancy, and lactation is controlled by steroid and peptide hormones and growth factors. To determine the role of the insulin-like growth factors (IGFs) in this process we developed a transgenic model using the whey acidic protein (WAP) gene to direct expression of rat IGF-I and human IGF binding protein-3 (IGFBP-3) to mammary tissue during late pregnancy and throughout lactation. High levels of expression of transgenic IGF-I and IGFBP-3 were seen in lobular-alveolar cells by in situ hybridization. There was no obvious effect on mammary development during pregnancy and lactation; indeed, mothers were capable of nursing their pups normally and the only structural difference seen in the mammary glands at peak lactation was an overall smaller size of the alveoli. We also evaluated the role of IGF-I and IGFBP-3 in the remodeling of mammary tissue during involution. Compared with control animals, the process of involution was modified in both transgenic lines. The degree of apoptotic cells was lower in the WAP-IGF-I and WAP-BP-3 expressing mice. In addition, there was a more quiescent pattern of involution with residual lobular secretary ability and a muted host inflammatory reaction with fewer lumenal microcalcifications. These results demonstrate that IGF-I and IGFBP-3 may modulate the involutionary process of the lactating mammary gland.

The growth-stimulatory effect of simian virus 40 T antigen requires the interaction of insulinlike growth factor 1 with its receptor.

We have used a plasmid expressing a temperature-sensitive (ts) mutant of simian virus 40 (SV40) T antigen, stably transfected into 3T3 cells, to study the role of insulinlike growth factor 1 (IGF-1) and its receptor in T-antigen-mediated growth. While 3T3 cells do not grow in serum-free medium, in 1% serum, or with the sole addition of either platelet-derived growth factor (PDGF) or IGF-1, cells expressing the tsA T antigen (BALB 58 cells) grow at 34 degrees C in either PDGF or 1% serum but not in IGF-1. At the restrictive temperature (39.6 degrees C), these cells can only grow in 10% serum. We show that BALB 58 cells, at 34 degrees C, have a markedly increased expression of IGF-1 and IGF-1 mRNA and that their growth in 1% serum (at 34 degrees C) is inhibited by an antisense oligodeoxynucleotide to the IGF-1 receptor RNA. When this tsA plasmid is stably transfected into cells constitutively overexpressing the human IGF-1 receptor cDNA, the resulting cell lines show a constitutively phosphorylated IGF-1 receptor and grow in serum-free medium at 34 degrees C (but not at 39.6 degrees C). A functional SV40 T antigen also increases the expression of a plasmid in which the reporter luciferase gene is under the control of a rat IGF-1 promoter. We conclude (i) that the SV40 T antigen induces the expression of IGF-1 and IGF-1 mRNA, at least in part by a transcriptional mechanism, thus altering the growth factors requirements, and (ii) that, in BALB/c3t3 cells, the SV40 T antigen necessitates a functional IGF-1 receptor for its growth-stimulating effect in low serum (or PDGF).

Inhibition of cellular proliferation by the Wilms' tumor suppressor WT1 is associated with suppression of insulin-like growth factor I receptor gene expression.

We have investigated the regulation of the insulin-like growth factor I receptor (IGF-I-R) gene promoter by the Wilms' tumor suppressor WT1 in intact cells. The levels of endogenous IGF-I-R mRNA and the activity of IGF-I-R gene promoter fragments in luciferase reporter constructs were found to be significantly higher in G401 cells (a Wilms' tumor-derived cell line lacking detectable WT1 mRNA) than in 293 cells (a human embryonic kidney cell line which expresses significant levels of WT1 mRNA). To study whether WT1 could suppress the expression of the endogenous IGF-I-R gene, WT1-negative G401 cells were stably transfected with a WT1 expression vector. Expression of WT1 mRNA in G401 cells resulted in a significant decrease in the rate of cellular proliferation, which was associated with a reduction in the levels of IGF-I-R mRNA, promoter activity, and ligand binding and with a reduction in IGF-I-stimulated cellular proliferation, thymidine incorporation, and anchorage-independent growth. These data suggest that a major aspect of the action of the WT1 tumor suppressor is the repression of IGF-I-R gene expression.

T cell receptor-induced activation and apoptosis in cycling human T cells occur throughout the cell cycle.

Previous studies have found conflicting associations between susceptibility to activation-induced cell death and the cell cycle in T cells. However, most of the studies used potentially toxic pharmacological agents for cell cycle synchronization. A panel of human melanoma tumor-reactive T cell lines, a CD8+ HER-2/neu-reactive T cell clone, and the leukemic T cell line Jurkat were separated by centrifugal elutriation. Fractions enriched for the G0-G1, S, and G2-M phases of the cell cycle were assayed for T cell receptor-mediated activation as measured by intracellular Ca(2+) flux, cytolytic recognition of tumor targets, and induction of Fas ligand mRNA. Susceptibility to apoptosis induced by recombinant Fas ligand and activation-induced cell death were also studied. None of the parameters studied was specific to a certain phase of the cell cycle, leading us to conclude that in nontransformed human T cells, both activation and apoptosis through T cell receptor activation can occur in all phases of the cell cycle.

Silencing vimentin expression decreases pulmonary metastases in a pre-diabetic mouse model of mammary tumor progression.

Increased breast cancer risk and mortality has been associated with obesity and type 2 diabetes (T2D). Hyperinsulinemia, a key factor in obesity, pre-diabetes and T2D, has been associated with decreased breast cancer survival. In this study, a mouse model of pre-diabetes (MKR mouse) was used to investigate the mechanisms through which endogenous hyperinsulinemia promotes mammary tumor metastases. The MKR mice developed larger primary tumors and greater number of pulmonary metastases compared with wild-type (WT) mice after injection with c-Myc/Vegf overexpressing MVT-1 cells. Analysis of the primary tumors showed significant increase in vimentin protein expression in the MKR mice compared with WT. We hypothesized that vimentin was an important mediator in the effect of hyperinsulinemia on breast cancer metastasis. Lentiviral short hairpin RNA knockdown of vimentin led to a significant decrease in invasion of the MVT-1 cells and abrogated the increase in cell invasion in response to insulin. In the pre-diabetic MKR mouse, vimentin knockdown led to a decrease in pulmonary metastases. In vitro, we found that insulin increased pAKT, prevented caspase 3 activation, and increased vimentin. Inhibiting the phosphatidylinositol 3 kinase/AKT pathway, using NVP-BKM120, increased active caspase 3 and decreased vimentin levels. This study is the first to show that vimentin has an important role in tumor metastasis in vivo in the setting of pre-diabetes and endogenous hyperinsulinemia. Vimentin targeting may be an important therapeutic strategy to reduce metastases in patients with obesity, pre-diabetes or T2D.

Elevated tumor LDLR expression accelerates LDL cholesterol-mediated breast cancer growth in mouse models of hyperlipidemia.

Obesity is associated with an increase in cancer-specific mortality in women with breast cancer. Elevated cholesterol, particularly low-density lipoprotein cholesterol (LDL-C), is frequently seen in obese women. Here, we aimed to determine the importance of elevated circulating LDL, and LDL receptor (LDLR) expression in tumor cells, on the growth of breast cancer using mouse models of hyperlipidemia. We describe two novel immunodeficient mouse models of hyperlipidemia (Rag1-/-/LDLR-/- and Rag1-/-/ApoE (apolipoprotein E)-/- mice) in addition to established immunocompetent LDLR-/- and ApoE-/- mice. The mice were used to study the effects of elevated LDL-C in human triple-negative (MDA-MB-231) and mouse Her2/Neu-overexpressing (MCNeuA) breast cancers. Tumors derived from MCNeuA and MDA-MB-231 cells had high LDLR expression and formed larger tumors in mice with high circulating LDL-C concentrations than in mice with lower LDL-C. Silencing the LDLR in the tumor cells led to decreased growth of Her2/Neu-overexpressing tumors in LDLR-/- and ApoE-/- mice, with increased Caspase 3 cleavage. Additionally, in vitro, silencing the LDLR led to decreased cell survival in serum-starved conditions, associated with Caspase 3 cleavage. Examining publically available human data sets, we found that high LDLR expression in human breast cancers was associated with decreased recurrence-free survival, particularly in patients treated with systemic therapies. Overall, our results highlight the importance of the LDLR in the growth of triple-negative and HER2-overexpressing breast cancers in the setting of elevated circulating LDL-C, which may be important contributing factors to the increased recurrence and mortality in obese women with breast cancer.

Stimulation of tumor growth by recombinant human insulin-like growth factor-I (IGF-I) is dependent on the dose and the level of IGF-I receptor expression.

The insulin-like growth factors (IGF) I and II regulate metabolism, mitogenesis, differentiation, and apoptosis. The therapeutic uses of IGF-I have been discussed extensively; however, excessive activity of the IGF ligands and IGF-I receptor has been suggested as a factor in tumorigenesis. The inhibition of apoptosis by IGF-I is believed to be particularly important for the stimulation of tumor growth. This study examined whether systemic recombinant human IGF-I (rhIGF-I) therapy affects the growth of fibrosarcomas derived from fibroblasts expressing the IGF-I receptor at high or naturally occurring densities (1.9 x 10(5) compared with 1.6 x 10(4) IGF-I receptors/cell) in athymic nude mice. Treatment with 4 or 10 mg/kg rhIGF-I resulted in a marked reduction in the tumor latency and stimulated the growth of fibrosarcomas that overexpressed the IGF-I receptor. The latency and growth of fibrosarcomas expressing parental levels of the IGF-I receptor were not affected by rhIGF-I therapy. Analysis of mitosis by histone H3 mRNA in situ hybridization and of apoptosis by terminal deoxynucleotidyl transferase-mediated nick end labeling assay indicated that rhIGF-I-stimulated tumor growth was associated with a marked increase in mitogenesis; however, there was no evidence for any significant effect on apoptosis. These data imply that: (a) systemic rhIGF-I can stimulate the growth of tumors directly by stimulating mitosis; and (b) a reasonable level of IGF-I receptor expression is required for stimulation of tumor growth by systemic rhIGF-I.

IGFBP-3 gene expression and estrogen receptor status in human breast carcinoma.

Insulin-like growth factors (IGF) I and II are potent mitogens for breast carcinoma proliferation. IGF-mediated proliferative activity can be markedly enhanced by the presence of specific IGF-binding proteins (IGFBPs). IGFBP-3 has been shown to enhance IGF-mediated growth in a number of systems. Studies have demonstrated IGFBP-3 secretion only in estrogen receptor (ER)-negative breast carcinoma cell lines while IGFBP-3 could not be detected in media conditioned by ER-positive cell lines. We investigated whether a relationship exists between ER status and IGFBP-3 mRNA expression in human breast carcinoma biopsy specimens. We have detected IGFBP-3 mRNA in breast carcinoma tissue obtained from patients utilizing in situ hybridization. Quantitation of IGFBP-3 mRNA levels was performed utilizing image cytometry. There was a significantly higher expression of IGFBP-3 mRNA in ER-negative breast carcinoma specimens when compared to the ER-positive specimens. Whether this higher expression of IGFBP-3 mRNA and presumed secretion of IGFBP-3 by ER-negative tumors play a role in the rapid proliferation and poor prognosis of these tumors remains to be determined.

Evidence for multiple molecular weight forms of somatostatin-like material in Escherichia coli.

Extracts of Escherichia coli grown in defined medium contain somatostatin-related material (1-10 pg/g wet weight of cells). Preconditioned medium had no immunoactive somatostatin whereas, conditioned medium had 110-150 pg/l. Following purification of the extracted material on Sep-pak C18, Bio-Gel P-6 and HPLC, multiple molecular weight forms of somatostatin- (SRIF-) related material were identified. The material in one peak reacted in both the N-terminal and C-terminal SRIF immunoassay and coeluted on HPLC with SRIF-28, whereas that in a second peak eluted near SRIF-14 and was reactive only in the C-terminal SRIF assay. The two peaks are thus similar to SRIF-28 and SRIF-14 of vertebrates. These findings add support to the suggestion that vertebrate-type peptide hormones and neuropeptides have early evolutionary origins.