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Biomedical subjects

J Bower

Publications and source records attributed to J Bower.

53 records · Page 3Linked to original sources
PubMed1986

The importance of the abdominal viscera to peritoneal transport during peritoneal dialysis in the dog.

The authors sought to evaluate the dialyzing surfaces important for peritoneal dialysis. They reasoned that the most definitive way to evaluate whether any of the gut and associated membranes contributed to transport was to see if transport changed when they were removed. Paired studies measuring rates of peritoneal uptake of glucose, urea, and inulin were carried out in dogs. In the morning, the animals were tested with all peritoneal membranes intact. In the afternoon, the studies were repeated after evisceration. The mass transfer coefficients (MTC ml/min)--glucose (viscera 4.4 +/- 0.7, no viscera 4.9 +/- 0.3)--urea (viscera 16.8 +/- 2.4, no viscera 13.8 +/- 1.0);--inulin (viscera 1.6 +/- 0.6, no viscera 2.2 +/- 0.7) were not changed nor was the amount of mass absorbed significantly different. MTC and peritoneal absorption were unaffected by omentectomy, mesenterectomy, or evisceration. Whether these results were due to nonparticipation of these structures in peritoneal transport or other mechanisms await further studies.

Absorption↗
PubMed1985

A double blind trial of dipyridamole in CAPD.

Since we had previously shown that dipyridamole augmented inulin and glucose clearance during intermittent peritoneal dialysis we sought to extend our study to the patient undergoing continuous ambulatory peritoneal dialysis. We carried out a double blind study in which patients received either 75 mg of active drug or placebo for a 2-week period. At the end of this period the mass transfer coefficients, between plasma and dialysate, were measured for selected solutes. We did not find any drug effect. The results of our first study together with the results of this study suggest that dipyridamole has no place in the chronic management of patients undergoing peritoneal dialysis.

Administration, Oral↗
PubMed1985

Evaluation of a peritoneal dialysis solution containing polymer.

Glucose is used in peritoneal dialysate to produce the gradient for ultrafiltration. The peritoneal membrane's low reflection coefficient for glucose imposes a demand for high transmembrane concentrations, perhaps adding unwanted body burden of glucose. A polymer with a lower permeation rate used as an osmotic agent would circumvent this. We evaluated the mass transfer coefficient (mtc), T1/2 disappearance from the peritoneal cavity and ultrafiltration capabilities of a 900 dalton (Mn) starch derived polymer. We compared an 8% (455 mOsm/L) and a 10% (484 mOsm/L) polymer (Pol) solution to available dialysate solutions containing 2.5% (399 mOsm/L) and 4.25% (491 mOsm/L) X glucose (Glc). The dialysate compositions were otherwise similar. Using a randomized complete block design, 5 anephric dogs maintained on chronic peritoneal dialysis were studied. The mtc (ml/min) was greater for the glucose than the polymer solutions (p less than 0.05): 2.5%-13 and 4.25%-14 vs 8%-5 and 10%-6. The T1/2 disappearance (min) was also greater (p less than 0.05): 2.5% Glc-112 and 4.25% Glc-111 vs 8% Pol-281 and 10% Pol-252. Over a 180 min. period the 2.5% glucose solution generated the least volume of ultrafiltrate (ml, p less than 0.05): 2.5% Glc-113 and 4.25% Glc-589 vs 8% Pol-640; 10% Pol-912. We conclude that the lower permeation rate of the polymer yields ultrafiltration at a lower dialysate osmolality. A polymer solution may be a feasible alternative to glucose.

Animals↗
PubMed1985

The expression of chick alpha A2-crystallin RNA during lens development and transdifferentiation.

During development of the vertebrate lens, the lens epithelium undergoes a final stage of differentiation into lens fibre cells, during which the major lens proteins, the crystallins, are synthesised. Lentoids, comprising clusters of lens fibre cells can also be produced by transdifferentiation from certain non-lens tissues, including neural retina and pigmented retinal epithelium. We have isolated an alpha A2-crystallin genomic probe and used it to study the transcription and processing of alpha A2-crystallin mRNA both during lens development and transdifferentiation. We relate these results to earlier measurements in this laboratory of delta-crystallin transcription and alpha- and delta-crystallin protein synthesis, to compare the expression of these two sets of genes. Tissue specific differences in gene expression were found. delta-crystallin mRNA is transcribed before alpha A2-crystallin RNA in the lens, but after it in transdifferentiating neural retina and pigmented epithelia.

Animals↗
PubMed1985

Substitution of a starch polymer for glucose in peritoneal dialysis.

We compared a starch-derived polymer (molecular weight = 900) as the osmotically active agent in peritoneal dialysate (3 and 6% solutions) to results obtained with commercially available glucose dialysate (1.5 and 4.25%). 12 dogs were dialyzed with glucose for 7 days, and 9 received the polymer for 5 days. For dialysate exchanges with an intraperitoneal residence of 240 min the 1.5 and 3% solutions generated similar volumes of ultrafiltrate as did the 4.25 and 6% solutions. However, for exchanges of 960 min the 1.5% dialysate was significantly reabsorbed when compared to the other dialysate concentrations. The serum polymer concentration increased with continued dialysis. The rate of transfer from dialysate to serum in man must still be determined. The lower diffusivity of the polymer will certainly be evidenced. For certain clinical applications where diminished ultrafiltration occurs, the polymer may be of benefit to man.

Animals↗
PubMed1984

Dialysate flow rate and peritoneal clearance.

We evaluated the influence of dialysate flow rates upon peritoneal clearance of urea, creatine, protein losses into dialysate, glucose disappearance from dialysate, sodium removal from the patient during dialysis, and ultrafiltration rate in 64 patients undergoing intermittent peritoneal dialysis. We evaluated three dialysate flow rates: 2 L/h, 3 L/h, and 4 L/h. All dialysate contained 1.5% glucose. The clearance of urea in milliliters per minute (2-L series 14.0, 3-L series 15.1, 4-L series 17.6) and creatinine in milliliters per minute (2-L series 9.3, 3-L series 10.6, 4-L series 11.6) determined at a dialysate flow rate of 4 L/h was significantly greater than the clearances determined at 3 and 2 L/h of dialysate flow (P less than 0.05). The clearance of glucose from the peritoneal cavity in milliliters per minute (2-L series 6.9, 3-L series 7.9, 4-L series 8.9) was significantly greater for the 4-L series as compared with the 2-L series (P less than 0.05). There were no other significant differences. Neither sex, race, previous episodes of peritonitis, nor etiology of renal failure influenced the results. Given the high cost of dialysate, we recommend dialysate flows of 2 L/h if a patient has a residual renal clearance of 2.5 mL/min. Although increasing dialysate flow rate may compensate for renal clearances significantly less than this, we believe the patient should be offered hemodialysis, continuous cyclic peritoneal dialysis (CCPD), or continuous ambulatory peritoneal dialysis (CAPD).

Creatinine↗
PubMed1983

Antibiotic activity in peritoneal dialysate.

There are few studies investigating whether antibiotics added to 30% glucose concentrate preserve their activity in the delivered dialysate. Using a Drake-Willock proportioning system, samples were obtained from the "to" patient path at ten minutes after starting and at four hours. Samples were tested for minimal inhibitory dilution (MID) against Escherichia coli and Staphylococcus aureus. Antibiotics evaluated included amikacin, tobramycin, gentamicin, cephalothin, cefamandole, moxalactam, ampicillin, penicillin, carbenicillin, and vancomycin. In all antibiotics studied, similar MIDs were obtained at the ten-minute and four-hour samples. Compared to saline, dialysate significantly impaired the antibiotic activity (a difference of two or more tube dilutions) of all antimicrobial agents except amikacin and vancomycin.

Anti-Bacterial Agents↗
PubMed1983

Comparison of home hemodialysis to continuous ambulatory peritoneal dialysis.

We evaluated prospectively various outcome measurements of patients assigned initially to continuous ambulatory peritoneal dialysis (CAPD) and home hemodialysis (HHD) from February 1979 to August 1981 and the causes for failures of the techniques. Morbidity was assessed by time in hospital/time on dialysis. Fifty-six patients were trained for CAPD and 37 for HHD. Those assigned to CAPD experienced an increased frequency of hospitalization (7.5% CAPD, 2.8% HHD, respectively) primarily due to episodes of peritonitis. There was also a higher modality failure rate (43% vs. 16%). However, the groups were not comparable in all respects. For example, the CAPD population included 21 patients with major cardiovascular diseases versus only three in the HHD group. The demographic characteristics of both populations including race, sex, age, income, place of residence, marital status, and education were similar. At the time of this study there is no direct evidence showing that healthy patients otherwise able to perform HHD may be maintained with less morbidity for a prolonged period utilizing CAPD. Therefore, we suggest that HHD is the home method of choice for patients able to proceed with this technique. CAPD may be indicated for patients in whom the period of home dialysis is expected to be relatively short and who would be otherwise unable to carry out home dialysis, for example, patients awaiting transplantation and those unable to be maintained on hemodialysis because of impaired cardiac function. To fully evaluate CAPD as a long-term maintenance therapy, a prospective trial must be performed.

Adult↗
PubMed1981

Peritoneal abnormalities during infectious episodes of continuous ambulatory peritoneal dialysis.

Exchanges were performed in 1-hour and 3- to 5-hour cycles when patients were noninfected and during episodes of peritonitis. The hourly exchange dialysate effluent volume decreased with the occurrence of peritonitis. These exchanges were associated with increased glucose absorption from dialysate, diminished sodium removal and augmented clearances of urea and creatinine. Protein losses were increased in the dialysate effluent of patients during an episode of peritonitis during the hourly exchanges. In the long-dwell exchanges obtained after clinical improvements of peritonitis, only protein losses were increased over control. Clearances, sodium loss in dialysate and glucose absorption were not altered from control.

Adult↗
PubMed1981

Evaluation of stagnant fluid films during simulated peritoneal dialysis: in-vitro and in-vivo studies.

Peritoneal dialysis as conventionally performed is an intermittent low dialysate flow system. Few studies have explored the effects of the intermittent nature of dialysate flow. Using an in-vitro model, we demonstrated that conventional peritoneal dialysis permits the development of stagnant fluid films and that by disruption of these films, dialysance could be augmented. We tested and confirmed these observations by carrying out peritoneal dialysis in rats. Stagnant fluid films may be an important contributor to overall membrane resistance in the peritoneal dialysis system

Animals↗
PubMed1981

Continuous ambulatory peritoneal dialysis. Treatment of dialysis-related ascites.

Continuous ambulatory peritoneal dialysis is a new dialysis technique. It is unknown at this time which patient would be served best by this therapy. Two cases of dialysis-related ascites were successfully treated by this technique. We suggest that the continuous control of salt and water balance possible with this technique, as well as frequent drainage of the peritoneal cavity to prevent fluid reaccumulations, contributed to successful treatment. Continuous ambulatory peritoneal dialysis may be used to treat dialysis-related ascites.

Adult↗
PubMedDate not supplied

In vitro myoblast to myotube transformations in the presence of leukemia inhibitory factor.

Leukemia inhibitory factor (LIF) is a pleiotropic cytokine which exerts a variety of effects on many cell types including neuronal cells, and is a potent mitogen for myoblasts. At concentrations of 0.1-0.3 ng/ml, the peptide stimulates a maximal increase in cell number. LIF initiates a prolonged proliferative response lasting up to 13 days, when myoblasts are exposed to it in culture. LIF expression can be detected in vivo during development of limb muscle and in adult regenerating skeletal muscle tissue. Here, we studied the levels of expression of alpha-bungarotoxin-binding sites as a measure of acetylcholine receptors (AChRs), myosin light chain pattern and rate of myotube formation in fused, control and LIF-treated muscle cultures derived from mouse hind-limb muscles. We found that both the level of expression of AChRs and myosin light chain pattern, are normal, following exposure of the cells to LIF. There was no difference in the rate of myotube formation between LIF-stimulated and control myoblasts over a 10-fold concentration range (0.3-3.0 ng/ml) as determined by nuclei counts. Taken together, these results suggest that LIF, in combination with other cytokines, may act in vivo to stimulate rapid growth, without significant differentiation, during the early phases of myogenesis.

Animals↗
PubMedDate not supplied

Intraperitoneal feeding.

This study evaluated the peritoneal cavity as the sole route for alimentation in 300 g growing rats. Initial studies demonstrated that a solution of high osmolality was required to provide sufficient calories. A nutrient solution was formulated by mixing 20% glucose with electrolytes (10 ml) and 8.5% amino acids with electrolytes (20 ml). Instilling 30 ml of nutrient solution induced an IP volume of 60 ml, which was absorbed in 24 hours. Rats were studied in four groups for 7 days. One group received nutrient solution IP (n = 10); a second group received the same amount PO (n = 10); the third group received electrolytes IP (n = 10); and a fourth group was fed rat chow PO (n = 10). Rats fed this nutrient solution (IP and PO) were acclimatized by administering one third of their required nutrient the first 4 days. On the next 3 days they received two thirds of their required nutrient. Both groups fed nutrient solution (IP and PO) lost 23% body weight. Electrolyte and rat chow fed groups lost 26% and gained 8% of body weight, respectively. Due to the high osmolality (1200 mOsm/L) of this nutrient solution, sufficient food could not be delivered via the peritoneal cavity to adequately feed growing rats. Studies were then initiated to formulate another nutrient solution that contained lipids. This solution (678 mOms/L) contained 20% glucose with electrolytes (10 mls), 8.5% amino acids with electrolytes (20 ml), and 10% lipids without electrolytes (30 ml). Glucose and amino acids contained the same electrolyte concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMedDate not supplied

Non-invasive determination of recirculation in the patient on dialysis.

Recirculation of blood flow occurs when the fistula flow rate is inadequate to support the desired dialyzer blood flow. The percentage recirculation is normally calculated using the blood urea nitrogen of blood samples from the two dialyzer blood lines and a peripheral blood sample. However, this method is time consuming, costly, and may not always give accurate measurements. A technique was developed to measure recirculation using the injection of saline into the venous dialysis line. For this technique, an optical detector is placed across the arterial dialysis tubing, and the light intensity, which is proportional to the hematocrit, is continually measured using a computerized data collection system. After a baseline data collection period, 10 ml of saline is injected into the venous dialysis line using the sampling port. The saline that appears in the arterial dialysis line as a result of recirculation will cause a dilution of the blood and an increase in light intensity. In vitro testing showed an excellent correlation between the area under the dilution curve and percentage recirculation. This technique will provide a quick, inexpensive, and reliable measurement of recirculation.

Arteriovenous Shunt, Surgical↗