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Dive into the research topics where James K. Rothrock is active.

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Featured researches published by James K. Rothrock.


Endocrine | 2000

Effects of growth hormone-releasing hormone-related peptide on stem cell factor expression in cultured rat Sertoli cells.

Rosemary Steinmetz; Nicholas Lazzaro; James K. Rothrock; Ora Hirsch Pescovitz

The growth hormone-releasing hormone (GHRH) gene produces a precursor molecule that contains GHRH and a carboxyl-terminal peptide that we have named GHRH-related peptide (GHRH-RP). This peptide, like GHRH, stimulates the expression of stem cell factor (SCF), an important reproductive and hematopoietic cytokine, in vitro and in vivo. In the present study, using primary cultures of rat Sertoli cells, we compared the time course of action and the level of SCF stimulation seen following treatment with GHRH-RP and GHRH. Additionally, we investigated the activity of a truncated peptide, p75-92NH2, whose sequence is contained within GHRH-RP. All three of these peptides were shown to stimulate the steady-state levels of SCF mRNA to a comparable degree. However, the time course of action for GHRH-RP differed markedly from that of GHRH. GHRH-RP and p75-92NH2, similar to GHRH, induce SCF expression, at least in part, via the activation of the protein kinase A/cyclic adenosine monophosphate intracellular signaling pathway.


Endocrine | 1996

Peptides of the growth hormone-releasing hormone family : Differential expression in rat testis.

Beverly S. Monts; Paul R. Breyer; James K. Rothrock; Ora Hirsch Pescovitz

Growth hormone-releasing hormone (GHRH) belongs to a family of peptides expressed at high levels in the brain and digestive system of mammals. We have identified GHRH mRNA and peptide in rat and human germ cells, and detected a GHRH receptor mRNA in Sertoli cells. GHRH treatment of cultured Sertoli cells results in accumulation of cAMP and increased expression ofc-fos and stem cell factor (SCF), two factors critical for normal germ cell development. The current study was designed to localize within testis the transcription of other members of the GHRH family, and their receptors, and to determine if they also stimulate SCF. RNAs from separated testicular cells were amplified by comparative reverse transcription-polymerase chain reaction (RT-PCR). Southern blot analysis of the PCR products verified the presence of five GHRH family peptide and receptor transcripts in distinct testicular cell types. Transcripts encoding VIP and glucagon, and the receptors for pituitary adenylate cyclase activating peptide (PACAP) and glucagon, were detected predominantly in Leydig cells. In contrast, expression of GHRH, PACAP, secretin, and secretin receptor predominated in germ cells. Receptors for GHRH and VIP were expressed equally in all testicular cell types. To determine if, like GHRH, any of these other peptides activate Sertoli cell expression of SCF, primary Sertoli cell cultures were treated for 4–6 h with 10 or 100 nM of each individual factor. There was no consistent stimulation of SCF mRNA by VIP, PACAP, glucagon, or secretin. Differential expression of these peptides and their receptors suggests that they may each have unique paracrine functions within the testis.


Pediatric Research | 1998

Localization of a Novel Growth Hormone Releasing Hormone (GHRH) Precursor C-Terminal Peptide Product, GHRH-Related Peptide, in the Rat Ovary. |[dagger]| 414

Linda A. DiMeglio; Diana L Carlone; James K. Rothrock; Ora Hirsch Pescovitz

The gene which encodes growth hormone releasing hormone (GHRH) arose from an ancestral gene that also gave rise to the genes for vasoactive intestinal peptide (VIP), pituitary adenylyl-cyclase activating polypeptide (PACAP), glucagon, and secretin. Review of the GHRH gene sequence predicts a second 30 amino acid carboxyl terminal peptide product that has a high degree of homology with VIP and PACAP. This novel peptide, which we have called GHRH-related peptide (GHRH-RP), has been previously localized to rat testicular germ cells. GHRH-RP activates Sertoli cell expression of stem cell factor. Although GHRH is produced by a variety of rat tissues, including the hypothalamus, placenta, testis, and ovary, GHRH-RP has only been described in the testis. We sought to determine if this novel peptide is present in the cycling rat ovary.


Pediatric Research | 1993

GERM CELL LOCALIZATION OF TESTICULAR GROWTH HORMONE RELEASING HORMONE (GHRH)

P Breyer; C Srivastava; M Percdo; James K. Rothrock; M Collard; Ora Hirsch Pescovitz

Hypothalamic releasing hormones have been found outside of the CNS, however, their extrahypothalamic function remains largely unknown. We have identified a testicular GHRH-like peptide and mRNA in human and rat testis. Human testis, like hypothalamus and placenta, contains an abundant 750bp GHRH mRNA. Rat testis has been shown to produce a larger mRNA of 1750bp. This study was designed to localize GHRH production in testis. Rat testes were fractionated following collagenase and trypsin digestion. Germ cells were further separated by sedimentation, using a staput device. Total RNA was extracted from each cell population by the guanidinium thiocyanate method. Northern analysis, using a 32P-labeled riboprobe complementary to a GHRH cDNA (gift of R. Evans), revealed an abundant 1750bp transcript in spermatocytes, round spermatids and, to a lesser extent, in Sertoli cells. No transcript was detected in RNA from elongating spermatids, Leydig cells, or epididymis. Further localization by in sint hybridization using this probe, revealed prominent labeling of early spermatogenic cells. Because human germ cell cancers are the result of dysregulated growth of undifferentiated spermatogenic cells, we probed the Tera-2 and NT2D1 human germ cell cancer lines with the GHRH riboprobe. Like hypothalamus and human testis, a 750bp transcript was clearly delectable in both cell lines. To determine if GHRH might play a role as an autocrine mitogenic factor in these cancers, we evaluated thymidine incorporation into Tera-2 celis following treatment with GHRH (100nM). There was a 52% increase in thymidine incorporation suggesting that GHRH can induce DNA synthesis in these cells. We conclude that GHRH is produced in normal and cancerous germ cells and speculate that it may function as a local testicular growth factor.


Endocrinology | 1989

Evidence that Angiotensin-II and Potassium Collaborate to Increase Cytosolic Calcium and Stimulate the Secretion of Aldosterone*

Pratt Jh; James K. Rothrock; Dominguez Jh


Endocrinology | 1995

Presence of a spermatogenic-specific promoter in the rat growth hormone-releasing hormone gene.

Carolyn H. Srivastava; B. S. Monts; James K. Rothrock; Malusa J. Peredo; Ora Hirsch Pescovitz


Endocrinology | 1993

A new target for growth hormone releasing-hormone action in rat: the Sertoli cell.

Carolyn H. Srivastava; Paul R. Breyer; James K. Rothrock; Malusa J. Peredo; Ora Hirsch Pescovitz


Endocrinology | 1996

A novel peptide from the growth hormone releasing hormone gene stimulates Sertoli cell activity.

Paul R. Breyer; James K. Rothrock; N Beaudry; Ora Hirsch Pescovitz


Endocrinology | 1993

Germ cell localization of a testicular growth hormone-releasing hormone-like factor

Carolyn H. Srivastava; Michael W. Collard; James K. Rothrock; Malusa J. Peredo; Susan A. Berry; Ora Hirsch Pescovitz


American Journal of Physiology-renal Physiology | 1991

Na(+)-Ca2+ exchange and Ca2+ depletion in rat proximal tubules.

Jesus H. Dominguez; Carol Mann; James K. Rothrock; Veena Bhati

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