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Biomedical subjects

H Moore

Publications and source records attributed to H Moore.

At least 55 records · Page 3Linked to original sources
PubMed1994

Monoamine activity in anterior hypothalamus of guinea pig pups separated from their mothers.

Brief isolation in a novel environment increased the ratios of 3-methoxy-4-hydroxyphenylethylene glycol to norepinephrine (MHPG:NE) and dihydroxyphenylacetic acid to dopamine (DOPAC:DA) in the anterior hypothalamus of guinea pig pups. Ratios were significantly elevated after 90 min of isolation and for MHPG:NE, after 30 min of isolation; changes were due to increases in MHPG and DOPAC. Home cage isolation produced no change in any measure of catecholamine activity. No changes in levels of serotonin or its metabolite were observed. In 1 experiment, resting levels of NE and DOPAC:DA were predictive of the rate of separation-induced vocalization. Maternal separation in the context of novelty increases hypothalamic NE and DA activity; however, both isolation and novelty are required because neither maternal separation in the home cage nor exposure to a novel cage together with the mother had any discernible effect.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1993

Bidirectional modulation of stimulated cortical acetylcholine release by benzodiazepine receptor ligands.

In vivo microdialysis was used to determine the ability of benzodiazepine receptor (BZR) ligands to modulate stimulated cortical acetylcholine (ACh) efflux in awake, freely-moving Fischer-344/BNNia rats. Cortical ACh efflux was reliably enhanced during presentation of a complex stimulus (exposure to darkness coupled with presentation of a small amount of palatable food) in animals entrained with that stimulus. Administration of the BZR selective inverse agonist ZK 93,426 (5.0 mg/kg, i.p.) potentiated the ability of the darkness/food stimulus to enhance efflux, whereas administration of the BZR full agonist, chlordiazepoxide (5.0 mg/kg, i.p.) blocked the enhancement. The interaction of the BZR ligands with the entrained stimulus in affecting cortical ACh efflux was not secondary to effects on motor activity. These results, combined with results from a previous study, suggest that modulation of cortical ACh efflux by BZR ligands is bidirectional and dependent on the level of activity within cortical cholinergic neurons. This relationship enables the trans-synaptic stimulation of cortical ACh transmission by BZR inverse agonists to be most effective during behavioral activities which recruit the basal forebrain cholinergic system.

Acetylcholine↗
PubMed1992

Age-dependent modulation of in vivo cortical acetylcholine release by benzodiazepine receptor ligands.

In vivo microdialysis was utilized to determine the effects of benzodiazepine receptor (BZR) ligands on cortical acetylcholine (ACh) release in awake young and aged rats. There were no significant differences in baseline cortical ACh release as a function of age. While administration of the BZR selective inverse agonist ZK 93 426 increased ACh release in both groups of animals, the aged rats exhibited a greater stimulation. Unexpectedly, under the present testing conditions, the BZR agonist chlordiazepoxide (CDP) had no systematic effect on ACh release in either group. The presence or absence of these drug effects or drug-age interactions was not secondary to the impact of these compounds on behavioral activity. Cortical ACh release could also be stimulated by turning off the lights in the observation room or by the systemic administration of scopolamine. Aged rats were at least as able as their younger counterparts to respond to these manipulations with increased release. These results suggest that basal and stimulated release of cortical ACh is not impaired at the ages studied. Moreover, selective inverse BZR agonists may be a potent way of trans-synaptically stimulating cortical cholinergic transmission.

Acetylcholine↗
PubMed1991

Sieving and reflection coefficients for sodium salts and glucose during peritoneal dialysis in rats.

The two-part studies reported herein address peritoneal membrane ultrafiltrate (UF) characteristics during peritoneal dialysis exchanges in rats. In the studies of part 1, the sieving coefficients for sodium, chloride, and total solutes during hydrostatic UF after instillation of rat serum into the peritoneal cavity of rats were calculated. Thirty-six rats were divided into six groups (N = 6) according to the following peritoneal dialysis exchange cycle times: 60, 120, 180, 240, 480, and 960 min. Thirty milliliters of pooled rat serum were infused i.p. with the animal being conscious except during infusion and drainage. The study showed in the early phase of exchanges, when oncotic and osmotic pressure gradients were absent, net UF presumably due to capillary hydrostatic pressure and sodium sieving during such UF. Sieving coefficients for sodium (0.72), chloride (0.77) and total solutes (0.73) were determined by using standard formulae. In the second part of these studies, the kinetics of fluid movement after the instillation of 5% dextrose solution into the peritoneal cavity of rats were analyzed. A very low UF rate was observed early in the exchange when the glucose gradient between the dialysis solution and blood was at its peak. The UF rate gradually increased as the sodium entered the dialysis solution from the blood. At the time of low UF rate with high glucose gradient, presumably the osmotic pressure generated by the glucose in the dialysis solution was countered by the osmotic pressure of solutes in plasma, i.e., sodium and its anions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Effect of peritonitis on insulin and glucose absorption during peritoneal dialysis in diabetic rats.

The intraperitoneal route is frequently used for the administration of insulin in diabetic continuous ambulatory peritoneal dialysis patients. However, there is conflicting evidence as to whether the dosage of intraperitoneal insulin should be increased or decreased during peritonitis in these patients. Glucose and insulin absorption and glycaemic control were evaluated in 2-hour exchanges using 15 ml of 2.5% dextrose dialysis solution in diabetic rats with (group 1) and without (group 2) peritonitis. Fasting blood glucose values at the beginning of the study exchanges were mean +/- SD 17.9 +/- 3.3 mmol/l in group 1 and 18.2 +/- 3.5 mmol/l in group 2. Even though group 1 had a higher percentage absorption of dialysate glucose (65 +/- 19 vs. 47 +/- 7%; p less than 0.05) and higher percentage absorption of dialysate insulin (49 +/- 12 vs. 44 +/- 14%; p less than 0.1), the hypoglycaemic response to the standard intraperitoneal dose of insulin was similar in each group. Plasma C peptide levels remained very low in both groups, thus excluding significant endogenous release of insulin. These data indicate that peritonitis per se does not change intraperitoneal insulin requirements during standardized peritoneal dialysis exchanges in diabetic rats. Insulin requirements may also be unaltered during peritonitis in diabetic continuous ambulatory peritoneal dialysis patients, provided that dialysate glucose load and oral carbohydrate intake are kept constant.

Absorption↗
PubMed1990

Defining adequacy of CAPD with urea kinetics.

The purpose of this paper is to explore the validity of applying urea kinetic indices to CAPD. According to the peak concentration hypothesis, the values of Kt/V required for adequate dialysis are lower for CAPD than for hemodialysis because of the continuous steady state nature of CAPD. Pilot clinical studies were undertaken in 19 patients to correlate the (Kt/V)urea index with clinical assessment of adequacy based on a 12 parameter score. The data shows that the correlation between serum urea nitrogen (Kt/V)urea and protein catabolic rate (PCR) are in keeping with the theoretical predictions of the urea kinetic model. PCR and dietary protein are well correlated. Also, PCR and Kt/V had a high degree of positive correlation. Serum creatinine was inversely correlated with (Kt/V)creatinine. In 74% of the patients, the clinical assessment of adequacy was in agreement with the (Kt/V)urea domains of adequacy established from the peak concentration hypothesis and the urea kinetic model. The lack of correlation in the remaining 26% is being investigated.

Blood Urea Nitrogen↗
PubMed1989

Treatment of recurrent spontaneous abortion by immunization with paternal lymphocytes: correlates with outcome.

Previous observations have suggested that defective recognition of fetal alloantigens by the maternal immune system is associated with recurrent pregnancy failure and that this may be prevented by boosting the maternal immune system with paternal or pooled third-party leukocytes. The mechanism whereby this process achieves success is not clear, and accordingly to explore this we immunized 28 couples with recurrent fetal loss with 80 x 10(6) paternal peripheral blood mononuclear leukocytes (PBML) and followed various immunological parameters. The couples studied, in whom 55% achieved a successful pregnancy, showed no increase in sharing of human lymphocyte antigen (HLA)-A, -B, or -DR antigens and no consistent evidence of a decreased mixed leukocyte reaction (MLR) or MLR plasma-blocking factors compared with control couples. Immunization did not alter these parameters but did induce antipaternal lymphocytotoxins, although the presence of the latter did not correlate with pregnancy outcome. There was a correlation between rapid conception after immunization and a subsequent successful pregnancy. A successful pregnancy also correlated with sustained postimmunization, postconception maternal antipaternal allospecific CD-8+ suppressor T cells. Although these findings provide overall evidence that immunization produces changes in the way in which the maternal immune system interacts with the fetus, larger numbers of couples and a higher dose of paternal lymphocytes will be needed to establish clearly whether this therapy works and its mechanism of action.

Abortion, Spontaneous↗
PubMed1988

Kinetics of peritoneal dialysis in children: role of lymphatics.

Intraperitoneal fluid is absorbed continuously by convective flow into the peritoneal cavity lymphatics. We evaluated the role of lymphatic absorption in the kinetics of peritoneal dialysis during standardized four hour exchanges in six children using 40 ml/kg of 2.5% dextrose dialysis solution. Cumulative lymphatic absorption averaged 10.4 +/- 1.6 ml/kg and reduced the total net transcapillary ultrafiltration during the dwell time by 73 +/- 10%. Due to the considerable lymphatic absorption rate, maximum intraperitoneal volume was observed before osmolar equilibrium. Extrapolated to four study exchanges per day, lymphatic absorption decreased the potential daily drain volumes in the children by 27 +/- 5% and daily peritoneal urea and creatinine clearances by 24 +/- 4% and 22 +/- 5%, respectively. Compared with four hour exchanges using two liters of 2.5% dextrose dialysis solution in 10 adult CAPD patients with average peritoneal transport, the children had more rapid equilibration of urea, greater absorption of dialysate glucose, higher lymphatic absorption and lower net ultrafiltration (P less than 0.01 to P less than 0.05). Lymphatic absorption therefore causes a relatively greater reduction in net ultrafiltration and solute clearances in children than in adults.

Adolescent↗
PubMed1988

Long-term outcome following programmed electrical stimulation in patients with high-grade ventricular ectopy.

To determine if programmed electrical stimulation (PES) could be utilized to identify patients with high-grade ventricular ectopy at low- or high-risk for sudden cardiac death, we performed PES in 40 patients with high-grade ventricular ectopy refractory to conventional antiarrhythmic agents. Twenty-one patients had a previous myocardial infarction, five had cardiomyopathy, six had hypertension, three had valvular heart disease and five had no known structural heart disease. The mean age was 50 years (range, 18 to 76). During programmed ventricular stimulation, eight patients had inducible sustained (more than 30 seconds) monomorphic ventricular tachycardia (Group I) but in 32 patients sustained ventricular tachycardia was not inducible (Group II). None of the five patients without structural heart disease were inducible while seven out of 21 (33%) patients with previous myocardial infarction had inducible ventricular tachycardia (VT). Antiarrhythmic therapy was instituted in patients with inducible VT; patients without inducible VT did not receive antiarrhythmic agents. In Group I, seven of the eight patients are alive (mean follow-up, 16 months) and in Group II, 28 of the 32 patients are alive (mean follow-up, 17 months). None of the five deaths were sudden. We conclude that in the absence of antiarrhythmic therapy, the incidence of sudden cardiac death is very low in patients with high-grade ventricular ectopy who do not have inducible monomorphic ventricular tachycardia during programmed ventricular stimulation.

Death, Sudden↗
PubMed1988

Pharmacological reduction of lymphatic absorption from the peritoneal cavity increases net ultrafiltration and solute clearances in peritoneal dialysis.

Lymphatic drainage from the peritoneal cavity occurs mainly via the subdiaphragmatic stomata and significantly reduces net ultrafiltration and solute clearances during long-dwell peritoneal dialysis. Intraperitoneal cholinergic drugs constrict these stomata and may reduce peritoneal cavity lymphatic absorption. We evaluated ultrafiltration kinetics, solute transport, and lymphatic drainage during single hypertonic exchanges in rats using 2.5% dextrose dialysis solution with and without added neostigmine. Net ultrafiltration was enhanced in the neostigmine group (p less than 0.01) by a reduction in cumulative lymphatic absorption (p less than 0.01) and without an increase in total transcapillary ultrafiltration during the dwell time. Likewise solute clearances were significantly augmented with neostigmine primarily due to the increase in dialysate drain volume (p less than 0.01) since dialysate/serum solute ratios were unchanged. Pharmacological manipulation of peritoneal lymphatic absorption provides an alternative means of increasing the efficiency of long-dwell peritoneal dialysis without altering peritoneal transport of solutes and water.

Absorption↗
PubMed1987

The kinetics of ultrafiltration during peritoneal dialysis: the role of lymphatics.

Net ultrafiltration was measured directly during hypertonic peritoneal dialysis exchanges in rats. Simultaneously, lymphatic absorption was measured by monitoring the disappearance of albumin in the instilled dialysis solution from the peritoneal cavity. The albumin method for measuring lymphatic absorption was also tested in rats absorbing Lactated Ringer's solution from the peritoneal cavity where absorption rate could also be measured directly. The findings suggest the following: 1.) lymphatic absorption rate is similar with both hypertonic dialysis solutions and Lactated Ringer's solution; 2.) lymphatic absorption is substantial and net ultrafiltration is well below true transcapillary ultrafiltration; and 3.) in our model, lymphatic absorption occurs at a relatively constant rate over six hours of dwell time.

Absorption↗
PubMed1987

Contribution of lymphatic absorption to loss of ultrafiltration and solute clearances in continuous ambulatory peritoneal dialysis.

The contribution of peritoneal cavity lymphatic absorption to ultrafiltration kinetics and solute clearances in continuous ambulatory peritoneal dialysis was evaluated in patients with normal (group 1) and high (group 2) peritoneal permeability X area during 4-h exchanges using 2 liters 2.5% dextrose dialysis solution with 30 g added albumin. Cumulative lymphatic drainage in all continuous ambulatory peritoneal dialysis (CAPD) patients averaged 358 +/- 47 ml per 4-h exchange and reduced cumulative net transcapillary ultrafiltration at the end of the exchange by 58 +/- 7.2%. The peak ultrafiltration volume was observed before osmotic equilibrium between serum and dialysate was reached and occurred when the net transcapillary ultrafiltration rate had decreased to equal the lymphatic absorption rate. Thereafter the lymphatic absorption rate exceeded the net transcapillary ultrafiltration rate, and intraperitoneal volume decreased. Extrapolated to 4 X 2 liters, 2.5% dextrose, 6-h exchanges per d, lymphatic drainage reduced potential daily net ultrafiltration by 83.2 +/- 10.2%, daily urea clearance by 16.9 +/- 1.9%, and daily creatinine clearance by 16.5 +/- 1.9%. Although lymphatic absorption did not differ between the two groups, lymphatic drainage caused a proportionately greater reduction in net ultrafiltration in group 2 (P less than 0.025), because these patients had more rapid dialysate glucose absorption (P less than 0.05) and less cumulative transcapillary ultrafiltration (P less than 0.01). These findings indicate that cumulative lymphatic drainage significantly reduces net ultrafiltration and solute clearances in CAPD and that ultrafiltration failure in CAPD occurs when daily lymphatic absorption equals or exceeds daily transcapillary ultrafiltration. Reduction of lymphatic absorption may provide a means for future improvement in the efficiency of CAPD.

Absorption↗
PubMed1987

Determination of bromide ion concentration in greyhound urine by ion chromatography.

An ion chromatographic method was used to determine Br ion in the urine of Greyhounds. Phenol was added to the urine, before filtration through a 30,000-molecular weight cutoff filter and to the eluant (pH 11, NaOH-Na2CO3), as a preservative. Urine from 103 racing Greyhounds resulted in a mean +/- SD of 3.60 +/- 2.72 mg of Br/L of urine. Urine samples obtained from a Greyhound, to which 2 g of KBr was administered, yielded a diurnal elimination pattern with a half-life of 7.6 days.

Animals↗
PubMed1985

The clinical value of free phenytoin levels.

The relationship between total and free phenytoin levels and drug toxicity was studied in 80 patients. Twenty-four were taking phenytoin alone. Drug toxicity was assessed by a "blind" rater using an eight-point standardized scoring system. The mean free phenytoin fraction was 0.076 in patients taking phenytoin alone or phenytoin and carbamazepine and 0.11 in patients taking valproic acid (p less than 0.001). The free fraction did not change with the total level over the range tested (6.7 to 39.9 micrograms/ml total phenytoin). There was a strong correlation between free and total levels (r = 0.84). Both free (r = 0.59) and total (r = 0.49) phenytoin levels were positively correlated with the toxicity score. Only total phenytoin levels showed a weak positive correlation with decreasing seizure frequency. Our results suggest that routine free phenytoin level monitoring is not necessary in most clinical situations.

Adolescent↗