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Biomedical subjects

J C Chisholm

Publications and source records attributed to J C Chisholm.

At least 19 recordsLinked to original sources
PubMed2025

Relapsed rhabdomyosarcoma: treatment recommendations from the European pediatric soft tissue sarcoma study group (EpSSG).

At least one-third of patients with localized rhabdomyosarcoma (RMS) and 60-70% of patients with metastatic RMS experience progressive disease or relapse. Following relapse, outcomes generally remain poor with limited treatment options and a high risk of subsequent recurrence. Optimal treatment requires a multidisciplinary approach incorporating chemotherapy with local control. Given the complexity of managing relapsed RMS and the challenges in developing effective treatment strategies, we aim to present clear and practical recommendations on the management of these patients across Europe. These recommendations were developed collaboratively by a group of pediatric and adolescent sarcoma experts from the European paediatric Soft Tissue Sarcoma Study Group. A careful review of the literature was performed to ensure that wherever possible recommendations are supported by the results of clinical trials or substantive retrospective reports. Such recommendations provide a standardized approach to managing relapsed cases, improving patient outcomes and offering a framework for clinicians to make informed decisions.

Humans↗
PubMed1995

Signaling by N- and C-terminal sequences of parathyroid hormone-related protein in hippocampal neurons.

Parathyroid hormone-related protein (PTHrP) is synthesized in the brain, and a single type of cloned receptor for the N-terminal portion of PTHrP and PTH is present in the central nervous system. Nothing is known about the physiological actions or signaling pathways used by PTHrP in the brain. Using cultured rat hippocampal neurons, we demonstrate that N-terminal PTHrP[1-34] and PTH[1-34] signal via cAMP and cytosolic calcium transients. The cAMP response showed strong acute (< or = 6 h) homologous and heterologous desensitization after preincubation with PTHrP or PTH. In contrast, the acute calcium response did not desensitize after preincubation with PTHrP; in fact, preincubation dramatically recruited additional responsive neurons. Unexpectedly, C-terminal PTHrP[107-139], which does not bind or activate the cloned PTH/PTHrP receptor, signaled in neurons via cytosolic calcium but not cAMP. Although some neurons responded to both PTHrP[1-34] and PTHrP[107-139], others responded only to PTHrP[1-34]. We conclude that certain hippocampal neurons exhibit dual signaling in response to PTHrP[1-34] and that some neurons have a receptor for C-terminal PTHrP that signals only via cytosolic calcium.

Animals↗
PubMed1988

Modulation by 1,25-dihydroxycholecalciferol of the acute change in cytosolic free calcium induced by thyrotropin-releasing hormone in GH4C1 pituitary cells.

Receptor-mediated regulation of prolactin synthesis by 1,25-dihydroxycholecalciferol (1,25(OH)2D3) in the pituitary cell strain GH4C1 is dependent on the concentration of extracellular calcium. We have now investigated the actions of 1,25(OH)2D3 on cytosolic free calcium concentrations [( Ca2+]i) in these cells using the fluorescent indicator quin2. Basal resting [Ca2+]i was unchanged in cells treated with 1 nM 1,25(OH)2D3 either acutely (from 0 to 15 min) or for periods of up to 48 h. However, the initial peak of the biphasic change in [Ca2+]i induced by thyrotropin-releasing hormone (TRH) was enhanced more than twofold in cells pretreated for 24 or 48 h with 1,25(OH)2D3. This 1,25(OH)2D3-enhanced calcium response was restricted to the initial phase of TRH action; the secondary plateau phase was unaffected. Neither the affinity nor number of TRH receptors nor the early time course of [3H]MeTRH binding to GH4C1 cells were affected by pretreatment with 1,25(OH)2D3. Because TRH binding was not altered, four sites along the intracellular signal transduction pathway of TRH action were examined. Neither protein kinase C activation nor inositol polyphosphate accumulation were enhanced in response to TRH, in 1,25(OH)2D3 pretreated cells, indicating that phosphatidylinositol hydrolysis was unchanged by pretreatment. A low concentration of ionomycin was used to probe the size of the nonmitochondrial intracellular calcium pool that is sensitive to TRH. Ionomycin was not able to mobilize more calcium from 1,25(OH)2D3 pretreated cells, indicating that TRH-responsive intracellular calcium stores were probably not enhanced by pretreatment. Chelation of extracellular calcium, however, did eliminate enhancement of the TRH response in 1,25(OH)2D3-pretreated cells. We conclude that 1,25(OH)2D3 modulates acute dynamic changes in [Ca2+]i induced by TRH without affecting basal [Ca2+]i. The mechanism of the enhanced response of 1,25(OH)2D3-pretreated cells to TRH appears to depend upon a postreceptor event independent of phosphatidylinositol hydrolysis that involves increased calcium conductance at the level of the plasma membrane. A less likely explanation involves enhancement of intracellular calcium stores in an ionomycin-resistant, EGTA-sensitive, TRH-mobilizable reservoir.

Animals↗
PubMed1988

Analysis of the fifth cell cycle of mouse development.

The 5th cell cycle of mouse development was analyzed to determine the lengths of each cell cycle phase. The DNA content of Feulgen-stained blastomere nuclei was measured at various times throughout the cell cycle by microdensitometry. To achieve precise timing of the start of the 5th cell cycle, experiments utilized isolated 16-cell blastomeres and cell pairs obtained by in-vitro division of isolated 8-cell blastomeres. The following estimates were made for a mixed population of polar and apolar 16-cell blastomeres: G1, less than or equal to 2 h; S, 8-9 h; G2 + M, 2 h. No significant difference was found in the timing of DNA synthesis between polar and apolar cells or between cell pairs and whole embryos.

Animals↗
PubMed1987

The establishment of the embryonic-abembryonic axis in the mouse embryo.

The influence of cell division order on the establishment of the embryonic-abembryonic axis (EA axis) of the mouse embryo was investigated. Aggregate embryos were constructed in which a labelled cell (or pair of cells) was combined with a group of unlabelled cells all of which were up to one cell cycle earlier or later in their progress through development to the blastocyst stage. The aggregates were cultured first to the nascent blastocyst stage and then to the expanded blastocyst stage. The positions of the progeny of the labelled cells in relation to the nascent blastocoel and to the orientation of the embryonic-abembryonic axis were recorded. It was concluded that cell division order does influence the establishment of the EA axis, early dividing cells tending to be associated with the nascent blastocoel and the site of the nascent blastocoel tending to mark the site of the abembryonic pole. However, the influence of division order was diminished by a requirement for intercellular cooperation during blastocoel formation and by a counteracting influence of division order arising from its effects on the allocation of cells to the inner cell mass.

Animals↗
PubMed1987

Cytokeratin filament assembly in the preimplantation mouse embryo.

The timing, spatial distribution and control of cytokeratin assembly during mouse early development has been studied using a monoclonal antibody, TROMA-1, which recognizes a 55,000 Mr trophectodermal cytokeratin (ENDO A). This protein was first detected in immunoblots at the 4-cell stage, and became more abundant at the 16-cell stage and later. Immunofluorescence analysis revealed assembled cytokeratin filaments in some 8-cell blastomeres, but not at earlier stages. At the 16-cell stage, filaments were found in both polarized (presumptive trophectoderm; TE) and apolar (presumptive inner cell mass; ICM) cells in similar proportions, although polarized cells possessed more filaments than apolar cells. By the late 32-cell, early blastocyst, stage, all polarized (TE) cells contained extensive filament networks whereas cells positioned inside the embryo tended to have lost their filaments. The presence of filaments in inside cells at the 16-cell stage and in ICM cells was confirmed by immunoelectron microscopy. Lineage tracing techniques demonstrated that those cells in the ICM of early blastocysts which did possess filaments were almost exclusively the progeny of polar 16-cell blastomeres, suggesting that these filaments were directly inherited from outside cells at the 16- to 32-cell transition. Inhibitor studies revealed that proximate protein synthesis but not mRNA synthesis is required for filament assembly at the 8-cell stage. These results demonstrate that there are quantitative rather than qualitative differences in the expression of cytokeratin filaments in the inner cell mass and trophectoderm cells of the mouse embryo.

Amanitins↗
PubMed1986

Transient, benign, serum alkaline hyperphosphatasemia in an adult.

A rare occurrence of transient, benign, serum alkaline hyperphosphatasemia (TBSAH) in an adult is described. This patient's serum alkaline phosphatase rose transiently and asymptomatically to 29 times the upper limit of normal. Although TBSAH has been described in the pediatric literature, no cases of this entity have been reported in adults. Awareness of TBSAH occurring in adults is equally important to physicians who care for adult patients.

Alkaline Phosphatase↗
PubMed1985

Ranitidine hydrochloride-induced hypergastrinemia.

Ranitidine hydrochloride (Zantac) is a recently released H(2)-receptor antagonist that is stated not to cause significant increases in serum gastrin. The case described herein demonstrates that this is not always true. Zantac produced significant acute hypergastrinemia, which was sustained for several days after the discontinuation of the drug.

Female↗
PubMed1985

Developmental variability within and between mouse expanding blastocysts and their ICMs.

We have attempted to reduce the developmental heterogeneity amongst populations of mouse blastocysts by synchronizing embryos to the first visible signs of blastocoel formation. Using embryos timed in this way, we have examined the extent of variation of inside and outside cell number and of inside cell size, nuclear DNA content and developmental potential, between and within embryos of a similar age postcavitation. The overall impression gained is one of wide heterogeneity in inside:outside cell number ratios and in cell cycling and its relation to cavitation among embryos of similar age postcavitation. However, the simplest explanation of our results suggests that cavitation generally begins at a time when most outside cells are in their sixth developmental cell cycle and that outside cells, as a population, are a little ahead of inside cells in their cell cycling. Additionally we present evidence that, within at least some individual inner cell masses (ICM), there is intraembryo variation in the time at which inside cell developmental potential becomes restricted.

Animals↗
PubMed1985

Quinidine-induced nephrotic syndrome.

A case of nephrotic syndrome occurring in an elderly woman who was being treated with quinidine is described. The nephrotic syndrome resolved completely after discontinuation of quinidine treatment. It is felt that the use of quinidine was causally related to the development of nephrotic syndrome in this patient. As far as could be determined, no such case has been described previously in the medical literature in English.

Female↗
PubMed1984

Trophectodermal processes regulate the expression of totipotency within the inner cell mass of the mouse expanding blastocyst.

Mouse blastocysts, aged 0, 2, 6 and 12 h from the onset of cavitation, were examined by transmission (TEM) and scanning (SEM) electron microscopy. In TEM sections, trophectoderm cells (TE) differed morphologically from those of the inner cell mass (ICM) by their flattened shape, paler cytosol staining and polarized disposition of both junctional complexes (apicolateral) and intracellular secondary lysosomes (SL; basal). Throughout this period of development, cytoplasmic processes, characterized by abundant SLs, cover approximately 80% of the juxtacoelic face of the ICM. These processes are shown to be derived from the basal surface of TE cells intermediately placed between polar and mural regions. In SEM preparations of the juxtacoelic ICM surface, revealed by 'cracking open' blastocysts, the processes appear as tongue-shaped, centripetally oriented structures which terminate collectively at a central area on the ICM surface. The potential of cultured ICMs to generate TE was demonstrated following their immunosurgical isolation from blastocysts aged up to 12 h post cavitation and by examining the sequence of ultrastructural changes associated with TE generation by ICMs from 2 h blastocysts. In contrast, the juxtacoelic cells of similarly aged ICMs observed in situ in ultrasections of intact embryos showed little or no evidence of totipotency expression as judged by the absence of TE characteristics. Since TE expression within presumptive ICM cells is thought to be generated by an asymmetry of cell contacts (Johnson & Ziomek, 1983), we propose that the juxtacoelic TE processes, by providing a cellular cover to the ICM, function in suppressing the expression in situ of ICM totipotency.

Animals↗
PubMed1983

Vestibular dysfunction presenting as syncope.

A case of chronic vestibulitis presented as episodes of recurrent drop attacks that had been interpreted as recurrent syncopal episodes. The importance of distinguishing between syncope and drop attacks-a difficult task-is emphasized. This case stresses the need to include benign vestibulitis in the differential diagnosis of syncope and drop attacks.

Diagnosis, Differential↗
PubMed1982

Bronchogenic carcinoma, leukemoid reaction, marantic endocarditis, and consumptive thrombocytopathy.

This paper details the simultaneous occurrence of a severe leukemoid reaction, non-bacterial thrombotic endocarditis (NBTE) (marantic endocarditis), and a consumptive thrombocytopathy without signs of micro-angiopathic hemolysis on peripheral blood smear in a patient with terminal metastatic, undifferentiated, large cell bronchogenic carcinoma. The case is presented and the condition is discussed in detail.

Blood Platelet Disorders↗
PubMed1981

Eosinophilic gastroenteritis with rectal involvement: case report and a review of literature.

An unusual case of eosinophilic gastroenteritis (EGE) is reported. Fewer than 150 cases of EGE have been reported in the world literature to date. This is the first case of this disease reported to have rectal involvement, and only the second case in which colonic involvement has been histologically documented. The addition of this case to those previously reported in the literature would suggest that EGE may involve any segment of the gastrointestinal tract.

Adult↗
PubMed1981

Hypozincemia, ageusia, dysosmia, and toilet tissue pica.

A 37-year-old female presented with complaints of ageusia, dysosmia, fatigue, and toilet tissue pica. She was found to have hypozincemia and iron deficiency anemia. Her complaints quickly abated when treated with oral zinc and iron.

Adult↗
PubMed1981

Acute low-dose hydralazine induced lupus syndrome (HILS).

A case of acute hydralazine induced lupus syndrome is described. No case has previously been described in which a small daily dose and a small accumulation dose have evoked this syndrome in such a short period of time. A pertinent and selective review of this syndrome is presented. The need for awareness of this syndrome manifesting in a patient exposed to small doses of hydralazine for short periods of time is emphasized.

Adult↗