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Biomedical subjects

C Moon

Publications and source records attributed to C Moon.

At least 37 records · Page 2Linked to original sources
PubMed1996

Combined liver and kidney transplantation.

Patients with end-stage renal and hepatic failure may be treated with combined liver and kidney transplantation (CLKTx). We reviewed the indications and outcomes of 16 CLKTx performed at the University of Minnesota between 1980 and 1994. The majority of the recipients (87.5%) were young patients affected by congenital hepatic anomalies and concomitant end-stage renal failure. Fourteen were treated with cyclosporin-based immunosuppression and had an excellent outcome: with an average of 6 years of follow-up, patient survival was 85.7%, liver graft survival 85.7%, and kidney graft survival 72%. The incidence of rejection episodes was similar to the rate of rejection in our solitary kidney and liver transplants. In conclusion, our experience supports the value of CLKTx in treating patients with simultaneous failure of both organs or with congenital enzymatic hepatic deficits leading to renal failure.

Adolescent↗
PubMed1995

The mouse aquaporin-1 gene.

Members of the aquaporin family of molecular water transporters are expressed in diverse epithelia and in complex developmental patterns. Using a cDNA for mouse Aqp1, the structural gene was isolated and a restriction map was constructed. The 13-kb Aqp1 gene contains four exons with intronic boundaries corresponding to other known aquaporin genes. Transcription begins 67 bp 5' to the translation initiation site and 20 bp 3' from a TATAA consensus sequence. Aqp1 was localized by interspecific mouse backcross mapping to the central region of mouse chromosome 6 syntenic with human chromosome 7p14, where AQP1 had previously been localized. These studies have revealed marked structural similarities between the mouse Aqp1 and the human AQP1 genes, suggesting that further comparative studies may provide molecular insight into genetic regulatory features shared by both species.

Animals↗
PubMed1994

Functional expression of 2-amino-4-phosphonobutyrate (APB) receptors in Xenopus laevis oocytes by injection of poly(A)+ RNA from quail brain.

The glutamate analogue 2-amino-4-phosphonobutyrate (APB) is known to activate a subtype of metabotropic glutamate receptor in the central nervous system, including the retina. In the present study, APB receptors were studied using the Xenopus oocyte expression system. No endogenous APB sensitivity was detected in control oocytes. In contrast, microinjection of mRNA, extracted from quail brain, into Xenopus oocytes resulted in the functional expression of APB receptors after 3-5 days incubation. Application of 50 microM-1 mM APB to injected oocytes voltage clamped at a holding potential of -60 mV produced a sustained outward current which was associated with a significant decrease in membrane conductance; the reversal potential was around -11 mV. The response to APB was dose-dependent and non-desensitizing. This is the first demonstration of the expression of a conductance-decreasing receptor mechanism in Xenopus oocytes.

Animals↗
PubMed1993

The human aquaporin-CHIP gene. Structure, organization, and chromosomal localization.

Aquaporin-CHIP is the first known molecular water channel. Originally identified in red cells and renal tubules, transcripts and proteins related to AQP-CHIP are also expressed in diverse epithelia with distinct developmental patterns. Northern analyses of RNA from several tissues revealed transcripts of 3.1 kilobases and other sizes. The nucleotide sequences of human kidney AQP-CHIP cDNAs are identical to the human bone marrow AQP-CHIP cDNA. The 17-kilobase human AQP-CHIP structural gene was isolated, and restriction maps were constructed and partially sequenced. The TATA consensus sequence is located 87 bp 5' to the translation initiation site, and sequences surrounding the polyadenylation consensus were determined. Four exons were identified corresponding to amino acids 1-128, 129-183, 184-210, and 211-269, separated by introns of 9.6, 0.43, and 0.80 kilobases. Genomic Southern analyses indicated the existence of a single AQP-CHIP gene which was located at human chromosome 7p14 by in situ hybridization. Sequence comparisons of AQP-CHIP and cDNAs of similar proteins from diverse species suggested a common evolutionary origin. At least three of these proteins are now known to function as membrane water pores and are referred to as the "Aquaporins." These genomic AQP-CHIP DNA sequences should permit molecular characterization of the complex patterns of AQP-CHIP expression.

Animals↗
PubMed1993

Aquaporin CHIP: the archetypal molecular water channel.

Despite longstanding interest by nephrologists and physiologists, the molecular identities of membrane water channels remained elusive until recognition of CHIP, a 28-kDa channel-forming integral membrane protein from human red blood cells originally referred to as "CHIP28." CHIP functions as an osmotically driven, water-selective pore; 1) expression of CHIP conferred Xenopus oocytes with markedly increased osmotic water permeability but did not allow transmembrane passage of ions or other small molecules; 2) reconstitution of highly purified CHIP into proteoliposomes permitted determination of the unit water permeability, i.e., 3.9 x 10(9) water molecules.channel subunit-1 x s-1. Although CHIP exists as a homotetramer in the native red blood cell membrane, site-directed mutagenesis studies suggested that each subunit contains an individually functional pore that may be reversibly occluded by mercurial inhibitors reacting with cysteine-189. CHIP is a major component of both apical and basolateral membranes of water-permeable segments of the nephron, where it facilitates transcellular water flow during reabsorption of glomerular filtrate. CHIP is also abundant in certain other absorptive or secretory epithelia, including choroid plexus, ciliary body of the eye, hepatobiliary ductules, gall bladder, and capillary endothelia. Distinct patterns of CHIP expression occur at these sites during fetal development and maturity. Similar proteins from other mammalian tissues and plants were later shown to transport water, and the group is now referred to as the "aquaporins." Recognition of CHIP has provided molecular insight into the biological phenomenon of osmotic water movement, and it is hoped that pharmacological modulation of CHIP function may provide novel treatments of renal failure and other clinical problems.

Amino Acid Sequence↗
PubMed1992

Canonical and non-canonical syllable discrimination by two-day-old infants.

Canonical syllables may be important units in early speech perception as well as production. Twenty infants (mean age 51 hours) (and twenty controls) were tested for their ability to discriminate between members of syllable pairs which were either canonical (paet and taep) or non-canonical (pst and tsp). A discrimination learning method was used in which syllables signalled the availability of either a recording of the mother's voice or silence--one of which was presented if the infant began a sucking burst. Infants in the canonical condition changed sucking patterns during signals over an 18-minute experimental session and activated their mother's voice more than silence, consistent with previous experiments using mother's voice as a reinforcer. In the non-canonical condition, infants also changed sucking patterns but sucked more during the signal for quiet than mother's voice, contrary to previous findings. Differential sucking during the syllables indicated discrimination in both conditions, but infants responded differently depending upon whether the syllables were canonical or non-canonical. The activation of silence in the non-canonical condition may be the result of a preference for quiet, but it is better explained as a failure to progress to a level of differential responding that was reached by the canonical group.

Age Factors↗
PubMed1992

Subcutaneously implanted catheters reduce the incidence of peritonitis during CAPD by eliminating infection by periluminal route.

UNLABELLED: Recent experiences with Y-connectors suggest that the flush-before-fill effectively reduces intraluminal infection. Periluminal infection, however, remains an important route of peritonitis (P). We have recently reported reduced P incidence with the introduction of a new access technique as described by Moncrief in which the external segment of peritoneal catheter is left implanted subcutaneously for 6 weeks before exteriorization and bag exchanges. P developed once every 14.0 patient-mos with the new access while the incidence was one episode per 10.7 mos with conventional access. Significantly fewer patients with the new access compared to those with conventional access experienced P during the observation period (p < 0.01). Although the overall incidence of exit-site infection (ESI) was not different, there were significantly fewer episodes of simultaneous P and ESI with the new access (2P in 47 episodes of ESI) than with conventional access (36P in 126 ESI). While 10 of the 36 episodes of simultaneous infection in the conventional technique were caused by same organisms, none of the 2 episodes with the new access technique was caused by same organisms. CONCLUSION: The results of this study suggest that the new access technique reduces P incidence by virtually eliminating infection by the periluminal route.

Adolescent↗
PubMed1992

Effects of erythropoietin-induced hemopoiesis on peritoneal transport and on in vitro T cell response in CAPD.

UNLABELLED: In order to investigate the therapeutic efficacy of subcutaneously administered erythropoietin (rHuEPO) and the effects of rHuEPO-induced hemopoiesis on peritoneal transport and on cellular immune responses, we performed standardized peritoneal equilibration tests and measured T cell subsets and phytohemagglutinin (PHA)-induced interleukin-2 receptor (IL-2R) expression of PBMC by flow cytometry before and after subcutaneous rHuEPO (Eprex-, Cilag), 4000 U twice weekly, in 13 stable CAPD patients. Hct increased from 21.3 +/- 3.4% to 30.0 +/- 4.8% after 1 mo and to 32.7 +/- 4.9% after 2 mon of rHuEPO. Drained volume after 4 hrs of dwell with 4.25% dialysate increased from 2,675 +/- 204 ml to 2,807 +/- 174 ml (P < 0.05). D4/P4 creatinine increased from 0.68 +/- 0.07 to 0.71 +/- 0.06 (P < 0.05) and creatinine clearance from 7.57 +/- 0.71 to 8.03 +/- 0.63 ml/min (P < 0.05). The number of total circulating lymphocytes, T4,T8, T4/T8 with or without PHA did not change after rHuEPO. PHA-induced IL-2R expression by PBMC as expressed by mean channel of fluorescence intensity increased from 149.8 +/- 6.7 to 156.8 +/- 6.1 (P < 0.05). CONCLUSION: Subcutaneous rHuEPO is effective in correcting anemia in CAPD patients. rHuEPO-induced hemopoiesis is associated with increase in peritoneal creatinine and water transport and also with PHA-induced IL-2R expression.

Adult↗
PubMed1990

Peritoneal solute clearances in diabetics.

In order to examine solute transport across the peritoneal membrane and responsiveness of the peritoneal microcirculation to a vasodilator in diabetics on continuous ambulatory peritoneal dialysis (CAPD), we obtained peritoneal clearances of urea (Curea) and creatinine (Ccr), protein concentrations in the drained dialysate (DPC), and percentage of peritoneal glucose absorption (% PGA) before and after nitroprusside (NP) addition to the dialysate in 13 diabetics (DM) and 13 nondiabetics (non-DM) matched for age, sex, body weight, and duration of CAPD. Control (before NP) Curea, Ccr, DPC, and %PGA were not different between DM and non-DM. NP significantly enhanced Curea, Ccr, and DPC in both DM and non-DM. Curea, Ccr, DPC, and %PGA after NP were again not different between DM and non-DM. The findings suggest that peritoneal solute clearances and responsiveness of the peritoneal microcirculation to NP in diabetics are not different from nondiabetics at the beginning of CAPD despite evidence for widespread vascular diseases in diabetic ESRD patients.

Biological Transport, Active↗
PubMed1985

Main and interaction effects of metallic toxins on classroom behavior.

This study investigated the relationships of metal levels and metal combinations to children's classroom behavior. Hair-metal concentrations of lead, arsenic, mercury, cadmium, and aluminum were determined in 80 randomly selected elementary-age children, who were also rated by their classroom teacher on the Walker Problem Behavior Identification Checklist (WPBIC). Parents were interviewed to control for confounding variables that may have affected behavioral development. Regression analysis indicated that the set of metals was significantly related to increased scores on four of the five WPBIC subscales and on the total scale, with lead being a major contributor to four of the six dependent measures. Metal combinations were significantly related to increased scores on the WPBIC subscales measuring acting-out, disturbed peer relations, and immaturity, and on the total scale. A continuing reexamination of metal poisoning concentrations is needed because metal levels and metal combinations previously thought harmless may be associated with nonadaptive classroom behavior.

Aluminum↗