Development of a Radioimmunoassay for Plasma C-Peptide in Sheep: Kinetics of C-Peptide and Effects of Exogenous Growth Hormone and Glucose on Insulin and C-Peptide

Leenanuruksa, D; McDowell, GH

doi:10.1071/bi9880517

Cited by 3 publications

(4 citation statements)

References 22 publications

(30 reference statements)

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“…Measurement of plasma C-peptide, the moiety joining the A and B chains of the pro-insulin molecule, allows assessment of insulin secretion rate (see Polonsky and Rubenstein 1984;Radziuk and Morishima 1985;Leenanuruksa and McDowell 1988). The sharp decrease in plasma C-peptide shortly after infusion of the 'priming' dose of somatostatin indicates a rapid and marked effect of somatostatin on insulin secretion.…”

Section: Discussionmentioning

confidence: 99%

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Insulin Affects Glucose Uptake by Muscle and Mammary Tissues of Lactating Ewes

Leenanuruksa¹,

Niumsup²,

McDowell³

1988

Aust. Jnl. Of Bio. Sci.

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Effects of insulin on exchanges of glucose across skeletal muscle and mammary tissue were measured in short-term studies in lactating ewes. Insulin secretion was suppressed by a primed/continuous infusion of somatostatin, then insulin was administered by continuous intravenous infusion of doses that were increased, in a step-wise manner, from 0 to 2 U h -I. Plasma glucose was maintained essentially constant by frequent monitoring and intravenous administration of exogenous glucose.Somatostatin suppressed but did not completely inhibit insulin secretion as shown by maintenance of plasma concentration of C-peptide. As plasma insulin was increased, while arterial glucose was maintained stable, uptake of glucose by skeletal muscle increased and glucose uptake by the mammary gland decreased. These observations confirm the role of insulin in regulating glucose uptake by skeletal muscle and raise the possibility that insulin also regulates glucose uptake by the mammary gland.

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Section: Discussionmentioning

confidence: 99%

“…Both assays measure bovine and ovine hormones with similar avidity (Leenanuruksa and McDowell, unpublished observations). Plasma concentrations of C-peptide were measured, within a week of collection of samples, by the method described by Leenanuruksa and McDowell (1988).…”

Section: Analysesmentioning

confidence: 99%

Insulin Affects Glucose Uptake by Muscle and Mammary Tissues of Lactating Ewes

Leenanuruksa¹,

Niumsup²,

McDowell³

1988

Aust. Jnl. Of Bio. Sci.

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“…Similar results were obtained by Ward et al (873). Growth hormone treatment for 1 day increased the plasma insulin concentration 7-fold and the proinsulin concentration 18-fold (656) in normal fasting dogs, while chronic treatment of sheep with GH increased the ratio of total immunoreactive insulin to C peptide (483). Such changes in insulin processing are also seen in other cases of insulin resistance (for review, see 424).…”

Section: Pancreatic Beta Ce/hmentioning

confidence: 53%

The Metabolic Actions of Growth Hormone

Goodman

2001

Comprehensive Physiology

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“…The highest serum level of human C-peptide was 4.49 ng/mL (1.5 nM) and the average was 1.51 ng/mL (0.5 nM) (Table 3). In lactating ewes, the basal concentration of C-peptide is 1.5–2.0 nM [26]. …”

Section: Resultsmentioning

confidence: 99%

In vivo generation of β-cell–like cells from CD34+ cells differentiated from human embryonic stem cells

Goodrich

Ersek

Varain

et al. 2010

Experimental Hematology

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Objective-CD34 + cells, present within the bone marrow, have previously been shown to possess pancreatic endocrine potential. Based on this observation, we explored the capacity of CD34 + cells derived in culture from the differentiation of human embryonic stem cells (hESC), for their in-vivo pancreatic endocrine capacity.Methods-Sheep were transplanted with hESC-derived CD34 + cells, as well as non-sorted differentiated cultures. Transplantations were carried out with in-utero intraperitoneal injections prior to the development of the immune system in the fetus so that tolerance towards foreign antigens was acquired during gestation and persisted in the adult.Results-All cell populations that were tested demonstrated human cellular activity and long-term presence up to 5 years. However, the in-vivo beta-cell-like activity achieved from the transplantation of the sorted CD34 + cell population was not augmented by transplanting the entire cell population from which the CD34 + cells were isolated. Human DNA and insulin mRNA were detected in sheep pancreases. An average of 1.51 ng/mL human C-peptide was detected in serum from 8 animals transplanted with differentiated cell populations and assayed up to 55 months post-transplantation. Transplantation of as few as 23,500 cells resulted in long-term sustainable beta-cell like activity. Teratomas were absent in the transplanted animals.Conclusion-Our data suggest that hESC-derived CD34 + cells have a potential for long term invivo endocrine cellular activity which could prove useful in regenerative medicine. Since the same cell population has previously been shown to contain hematopoietic potential, it could be used for the induction of immunological tolerance and bone marrow chimerism prior to cellular therapy for diabetes. KeywordsHuman embryonic stem cells; Pancreas; Transplantation; Beta-cells; C-peptide Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. One potential therapy for diabetics is the restoration of beta-cell mass for the endogenous control of glycemia [1,2]. To this end, human embryonic stem cells (hESC) which have the capacity to form tissues of all three germ layers cells [3], are being evaluated for cellular transplantation therapy. hESC differentiation cultures have been developed for the derivation of progenitor cells that engraft and differentiate in-vivo into beta-cell-like cells [4,5]. Such research has had to occur in the absence of knowledge of a single or a group of cell-surface markers that may be used to unequivocally identify and isolate pancreatic stem cells [6]. Hence, focus has been placed ...

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Development of a Radioimmunoassay for Plasma C-Peptide in Sheep: Kinetics of C-Peptide and Effects of Exogenous Growth Hormone and Glucose on Insulin and C-Peptide

Cited by 3 publications

References 22 publications

Insulin Affects Glucose Uptake by Muscle and Mammary Tissues of Lactating Ewes

Insulin Affects Glucose Uptake by Muscle and Mammary Tissues of Lactating Ewes

The Metabolic Actions of Growth Hormone

In vivo generation of β-cell–like cells from CD34+ cells differentiated from human embryonic stem cells

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