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Biomedical subjects

B R Collins

Publications and source records attributed to B R Collins.

18 recordsLinked to original sources
PubMed2000

Bile acids in xenogeneic ex-vivo liver perfusion: function of xenoperfused livers and compatibility with human bile salts and porcine livers.

BACKGROUND: In recent years, hepatic support systems using xenogeneic cells have been developed to support patients in fulminant hepatic failure. The extent to which xenogeneic hepatocytes metabolize and excrete human organic anions is unclear. In these studies we examined the ability of the ex vivo porcine liver to clear human bile acids during extracorporeal liver perfusion (ELP). METHODS: Four patients with fulminant hepatic failure underwent extracorporeal liver perfusion with 9 porcine livers. The venovenous circuit was designed as previously described (NEJM,1994,331:234) as were the immunologic features (Transplantation 1994,58:1162). Bile from the porcine liver and serum samples were collected hourly during perfusion. Three bile acids (glycocholic, glycodeoxycholic, taurodeoxycholic acid) were selected as markers for human bile and three (glycohyocholic, glycohyodeoxycholic, and glyco-3alpha-hydroxy-6-oxo-5beta-cholanoic acid) for markers of pig bile. Bile acids from both serum and bile were processed and analyzed through high performance liquid chromatography. The Students' t test was used for statistical analysis. RESULTS: The mean duration of perfusions was 4.1+/-1.5 hr. The mean total bile acid clearance from serum (243+/-44 micromol/h) was similar to the total bile acid biliary excretion (286+/-84 micromol/hr, P = 0.06). After 1 hr of perfusion, bile samples demonstrated a predominance of pig bile salts (65%). After 3 hr of perfusion, human bile acids made up 85% of total biliary bile acids. Pig bile acids appeared in patients' sera after 1 hr of perfusion, and after 3 hr, 35% of serum bile salts were pig-specific. CONCLUSIONS: Porcine livers perfused with human blood can clear the serum of potentially toxic human bile acids and excrete them into bile. Simultaneously, the percentage of pig-specific bile acids in patient serum increases during xenogeneic perfusion for unknown reasons. The relative hepatic uptake of bile acid from serum is similar to bile acid excretion in bile. Further development of systems using porcine livers or hepatocytes is warranted.

Animals↗
PubMed1998

Diurnal intraocular pressure curves in healthy rhesus macaques (Macaca mulatta) and rhesus macaques with normotensive and hypertensive primary open-angle glaucoma.

PURPOSE: The authors identify any diurnal intraocular pressure (IOP) variation in healthy Cayo Santiago macaques, as well as Cayo Santiago macaques with normotensive and hypertensive primary open-angle glaucoma (POAG), to further evaluate their potential value as a model for human POAG. METHODS: Twenty-four monkeys (eight animals each of the healthy control, normotensive glaucoma, and hypertensive glaucoma groups) were sedated with ketamine hydrochloride and the IOP measured hourly from 8:00 AM until 3:00 PM with a Tonopen XL applanation tonometer (Mentor, Norwell, MA, U.S.A.). Mean IOP time profiles, mean IOPs at each observation time, and linear trends in mean IOP over time were compared among groups. Intraocular pressure rate-of-change over time and residual variation about the regression line for each individual eye were analyzed. Cup/disc ratio (C/D) was compared with baseline IOP, IOP profile mean and slope, and IOP residual variation. RESULTS: A significant group and time effect on mean IOP (p = 0.0001 and 0.011, respectively), with highest values at 2:00 PM or 3:00 PM, and a significant increasing linear trend in mean IOP over time in the hypertensive group were observed (p = 0.012). Intermediate readings between control and hypertensive mean IOPs were identified for the normotensive glaucoma group. The biggest range of IOP variation was found in the hypertensive glaucoma monkeys. Higher variations in IOP did not lead to an increase in C/D. CONCLUSIONS: This study provides evidence that the Cayo Santiago macaques are a valuable model for human normotensive and hypertensive POAG.

Animals↗
PubMed1993

Detection of antibodies to a pathogenic mycoplasma in desert tortoises (Gopherus agassizii) with upper respiratory tract disease.

Mycoplasma agassizii (proposed species novum) is the etiologic agent of an upper respiratory tract disease in the desert tortoise (Gopherus agassizii), which is threatened in most of its range. An enzyme-linked immunosorbent assay (ELISA) for the detection of M. agassizii-specific antibodies in desert tortoises was developed with a monoclonal antibody with specificity for desert tortoise immunoglobulin light chain. Plasma samples from one group of tortoises were tested immediately before and 1 month after challenge either with nasal exudate containing M. agassizii or with a purified preparation of M. agassizii. Plasma samples from a second group of known healthy and sick tortoises were also tested. In the first group, the ELISA detected seroconversion in individual tortoises following challenge with M. agassizii. In the second group, ELISA results were positively correlated with the health status of the tortoises, as determined by clinical and pathologic findings. In addition, the ELISA revealed that tortoise antimycoplasma antibodies were specific for M. agassizii when samples were assayed against M. agassizii, M. pulmonis, M. testudinis, and M. gallisepticum antigens. The observed direct correlation between the presence of nasal mucosal lesions and M. agassizii-specific antibodies proved that the ELISA reliably diagnosed M. agassizii infection in desert tortoises and advocates its use for monitoring M. agassizii-induced upper respiratory tract disease in free-ranging desert tortoises.

Animals↗
PubMed1991

Sterilization and its behavioral effects on free-ranging female rhesus monkeys (Macaca mulatta).

In order to control population growth rates, a decision was made to sterilize most of the free-ranging, wild rhesus macaque females of Silver Springs, Florida. Between October 1987 and March 1988, the five females who had been sterilized and released in the fall of 1986 were matched with five intact females in a behavioral study. While there were differences between the behaviors of the sterilized and intact females, the differences can be attributed more to differences in age, rank, and other factors than to the sterilization. Clinical data collected and reported on the monkeys is unremarkable.

Agonistic Behavior↗
PubMed1991

Currency of full-text medical journals: CCML and MEDIS vs. MEDLINE.

The authors ask whether full-text versions of medical journals are available for searching sooner than their biblographic counterparts. The journals in question are those found in the Comprehensive Core Medical Library (CCML) from BRS Information Technologies and in Mead Data Central's MEDIS Current Journal Files. All journals in these two files are full-text, and neither file contains any indexing features. Update schedules for the full-text version of the MEDLINE journals in each of these files were compared with the most recent issue available in the National Library of Medicine's (NLM) MEDLINE on five different dates. The data revealed substantial fluctuation in comparative currency for MEDIS/MEDLINE over the period of the test. On the date of the last snapshot, June 8, 1990, MEDLINE and MEDIS were offering the same currency for 43% of the journals, and MEDIS was providing first access to 29% of the titles. The CCML/MEDLINE comparison showed less variation. In the last snapshot MEDLINE and CCML were providing access to the same issue for 36% of the journals, and CCML was offering first access to 14%. Prior to publication, this paper was submitted to all three vendors for comment. Significant portions of their responses are quoted.

MEDLINE↗
PubMed1989

Medical and surgical management of esophageal foreign body in a ferret.

A ferret was examined because of anorexia, repeated episodes of regurgitation, and subsequent dehydration. Radiography had revealed a radiodense midesophageal foreign body. Results of endoscopy of the esophagus, however, could not confirm the diagnosis. Contrast radiography revealed esophageal perforation, with subsequent penetration of the foreign body into the right pleural space, causing pleural effusion. Surgical repair of the esophagus was performed, and a gastrostomy feeding tube was inserted to provide adequate nutrition during esophageal healing. Nine days after surgery, radiography revealed a severe stricture at the esophageal surgical site. Surgery was repeated; the esophagus was transected, the stricture was removed, and esophageal tissues were closed in 2 layers. Systemically administered antibiotics and gastrostomy tube feedings were continued throughout the post-operative healing period. The esophagus healed with a mild stricture that diminished over time in response to corticosteroid administration.

Animals↗
PubMed1988

New attachment formation following controlled tissue regeneration using biodegradable membranes.

The present study evaluated the potential for reestablishment of connective tissue attachment after exclusion of the gingival connective tissue and epithelium during healing after periodontal surgery in a dog model. Buccal mucoperiosteal flaps were elevated in all four premolar regions in two dogs. The buccal bone was reduced to approximately 25% of its original level on 24 roots. Before the elevated flaps were replaced and sutured, membranes were adjusted to cover the exposed root surfaces. On eight surfaces Millipore filters were used and on eight surfaces biodegradable polylactic acid membranes were used. No membranes were placed over the remaining eight root surfaces which served as controls. After two months of healing, the animals were sacrificed and all the roots were subjected to histological analysis. In all of the roots covered with the polylactic acid membrane, newly formed cementum with inserting collagen fibers was observed and covered on the average 46% of the initial defect. Newly formed bone covered 39% of the initial defect. The roots covered by Millipore filters were characterized by significantly less new attachment and bone. In the control roots only minor new attachment was found in the bottom of the defect in some roots. The results suggest that the establishment of a connective tissue attachment is clearly favored by the placement of a polylactic acid membrane to exclude the epithelium and gingival connective tissue during healing.

Alveolectomy↗
PubMed1986

Surgical correction of eyelid disfigurement in a stumptailed monkey (Macaca arctoides).

Self-aggression in an adult male stumptailed monkey (Macaca arctoides) resulted in severe lower eyelid distortion, conjunctivitis and epiphora. The behavior ceased with a change in environment, but the eyelid defect, conjunctivitis and epiphora persisted, requiring corrective surgery. Surgical correction was partially successful, although the animal died due to unrelated medical problems before final correction could be accomplished.

Animals↗