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Biomedical subjects

B G Carter

Publications and source records attributed to B G Carter.

At least 19 recordsLinked to original sources
PubMed1998

Accuracy of two pulse oximeters at low arterial hemoglobin-oxygen saturation.

OBJECTIVE: To evaluate the performance of two pulse oximeters in the measurement of arterial hemoglobin saturation in hypoxemic children. DESIGN: Prospective, repeated-measures observational study. SETTING: A 16-bed pediatric intensive care unit in a children's tertiary hospital. PATIENTS: Sixty-six patients with arterial saturation of <90%. INTERVENTIONS: Three arterial blood samples were taken from each subject during a 48-hr period. Pulse oximeter measurements of arterial saturation were compared with arterial saturation determined by cooximetry. MEASUREMENTS AND MAIN RESULTS: Arterial saturation was measured using one or both pulse oximeters (SpO2) and compared with the arterial hemoglobin saturation determined by cooximetry (SaO2). Sixty-two subjects were studied, using the Ohmeda pulse oximeter giving 185 data points (78 with saturations <75% [defined by the average of pulse oximeter and cooximeter]); 53 subjects were studied, using the Hewlett-Packard pulse oximeter yielding 155 data points (60 with saturations <75%). SpO2 ranged from 24% to 94%. Bias and precision of the Ohmeda pulse oximeter were -2.8% and 4.8% >75% and -0.8% and 8.0% <75%. Bias and precision of the Hewlett-Packard pulse oximeter were -0.5% and 5.1% >75% and 0.4% and 4.6% <75%. Intrapatient regression coefficient (r) for the differences between pulse oximeter and cooximeter was 0.58 for the Ohmeda and 0.59 for the Hewlett-Packard. Regression coefficients for predicting change in cooximeter value given a change in the Ohmeda pulse oximeter were 0.59 and 0.71 <75% and >75%, respectively. Similar coefficients for the Hewlett-Packard pulse oximeter were 0.50 and 0.70, respectively. CONCLUSION: The performance of the Ohmeda pulse oximeter deteriorated below an SpO2 of 75%. The Hewlett-Packard pulse oximeter performed consistently above and below an SpO2 of 75%. The ability of both pulse oximeters to reliably predict change in SaO2 based on change in pulse oximetry was limited. We recommend measurement of PaO2 or SaO2 for important clinical decisions.

Child↗
PubMed1996

Influence of methylprednisolone acetate on osteochondral healing in exercised tarsocrural joints of horses.

OBJECTIVE: To evaluate joint function and healing of surgically created full-thickness articular cartilage defects in exercised horses after intra-articular administration of methylprednisolone acetate (MPA; 120 mg) and sterile saline solution in the contralateral limb. DESIGN: Experimental investigation. SAMPLE POPULATION: 12 healthy, sound, radiographically normal horses with induced full-thickness osteochondral lesions on the medial and lateral trochlear ridges of the tali. PROCEDURE: Two 8.4-mm-diameter full-thickness articular cartilage lesions were created in each tarsocrural joint (12 horses [24 tarsocrural joints]); 1 was in a weight-bearing (WB) position and the other in a less weight-bearing (LWB) position. Each horse was maintained on a standardized exercise protocol (stall rest, days 0-6; walking, days 7-12; and treadmill, days 13-42) and evaluated throughout the study for changes in joint circumferences, synovial fluid, radiographs, lameness, and scintigraphy. 6 horses were euthanatized on day 42, and 6 on day 180. Gross morphometric assessment was performed, using an image analysis system on a projected color slide of the defect. The type of repair tissue, based on gross appearance, was expressed as a percentage of the total defect for each osteochondral defect. Histochemical assessment was performed, using safranin-O staining for proteoglycans and an image analysis system to express the area of stain uptake. Histomorphometric assessment was performed on H&E-stained sections, using an image analysis system. The repair tissue filling the defect was categorized as to tissue type and expressed as a percentage of the total defect area. Synovial membrane specimens were assessed semiquantitatively on H&E-stained sections for changes in character. Significance was established at P < 0.05. RESULTS: Joint circumference was significantly increased in the saline, compared with the MPA-treated, limbs on days 7, 12, and 42. Synovial fluid WBC counts were significantly increased in the MPA-treated limbs on day 42. Gross osteochondral defects had a greater percentage of mature repair tissue in saline-treated joints (30.8% LWB, 23% WB), compared with MPA-treated joints (0% LWB, 0% WB) at 42 days Histomorphometric assessment of the repair tissue indicated significant differences with regard to the quality of repair in the saline-treated (34% fibrous tissue LWB, 19.4% fibrous tissue WB) versus MPA-treated (2.5% fibrous tissue in LWB and WB) joints at 42 days. Microscopically, the percentage of fibrocartilage in the LWB (MPA, 23.7%; saline, 24.8%) was significantly greater than that in the WB (MPA, 14.6%; saline, 15.4%) site at day 180. The MPA-treated limbs had greater villous hyperplasia, edema, and extent of inflammation within the synovial membrane than did saline-treated limbs (days 42 and 180). CONCLUSION: MPA inhibits the development and maturation of repair tissue at 42 days and incites potential long-term (180 days) detrimental synovial membrane inflammation. Furthermore, a single dose of MPA does not cause long-term detrimental effects (180 days) in quality of repair-tissue.

Animals↗
PubMed1995

Biomechanical properties of third carpal articular cartilage in exercised and nonexercised horses.

The relevance of site and exercise on the biomechanical properties of the articular cartilage from the equine third carpal bone were assessed by creep indentation testing. Six horses were exercised for 30 minutes three times weekly. Another six horses were housed in box stalls and were not exercised. At the conclusion of the study, one third carpal bone from each horse was harvested and the KLM biphasic material properties of cartilage were determined at 12 sites. There was a significant (p < 0.01) effect of site but not exercise on the cartilage aggregate modulus, which was significantly lower for sites on the dorsal aspect of the radial facet and for all sites on the intermediate facet as compared with sites on the palmar aspect of the radial facet of the third carpal bone. Exercise significantly increased the permeability constant at all sites when compared with the nonexercised group, but there was no difference between sites within groups. Exercise also significantly increased Poisson's ratio, but only at sites located on the palmar aspect of the radial facet. In general, both site and exercise influence the biomechanical behavior of third carpal articular cartilage. Inherent differences in cartilage biomechanical properties within a joint correlate with the location specificity of cartilaginous lesions in the equine midcarpal joint.

Analysis of Variance↗
PubMed1995

Measurement of respiratory rate and timing using a nasal thermocouple.

OBJECTIVE: The aims of this study were to assess aspects of the response of a small thermocouple to temperature change, and to evaluate whether such a thermocouple could be used intermittently to measure respiratory rate and timing by detecting the changes in nasal temperature occurring with breathing. METHODS: The study had three parts. First, three similar, fast-responding thermocouples were immersed repeatedly in warm water. Second, the influence of atmospheric temperature on the signal of a thermocouple placed at different sites within the nasal orifice was studied. The signals produced were continuously displayed and analyzed using a laptop computer to allow evaluation of the thermocouples' response characteristics. Third, simultaneous respiratory recordings were acquired using a nasal thermocouple and a nasal pneumotachograph in 12 teenaged subjects. The respiratory rate and the periods of time taken for inspiration (Ti) and expiration (Te) were calculated and compared. RESULTS: The thermocouples' responses to the temperature changes associated with breathing and immersion into water were rapid and consistent. The rate of the signals' decay, following the peak signal marking expiration, was influenced by the atmospheric temperature. The time constants of the thermocouples were similar (mean time constant = 0.41 sec, standard deviation (SD) = 0.07). Optimal respiratory recordings were obtained, with least discomfort, when the thermocouple was positioned at 0 to 4 mm within the nasal orifice. In comparing the respiratory recordings acquired simultaneously with a thermocouple and pneumotachograph, the respiratory rates were identical, and the Ti and Te values were similar (mean difference 0.04 sec (95% CI: -0.11 to 0.21 sec) and -0.04 sec (95% CI: -0.20 to 0.12 sec), respectively). CONCLUSIONS: Intermittent measurements of respiratory rate and timing using a nasal thermocouple accurately reflected measurements obtained from nasal airflow using a pneumotachograph.

Adolescent↗
PubMed1995

Median nerve somatosensory evoked potentials in children receiving ECMO.

Somatosensory evoked potentials (SEPs) were recorded from 11 patients receiving venoarterial extracorporeal membrane oxygenation (ECMO). Cortical responses recorded from the right and left hemispheres were compared to those from 2 other groups of children who were not receiving ECMO. One group consisted of 99 brain-injured patients, while the other consisted of a group of 17 neurologically normal controls. SEP responses from each hemisphere were categorized into 3 grades based on the N20 component--normal latency, abnormal (latency increased > 3 S.D.), or absent. For ECMO patients, 15% of tests disclosed a disagreement between the right and left hemispheres, while 27% of tests from the control group revealed a disagreement between the right and left hemispheres. SEPs were normal over the right hemisphere in 9 patients. Central conduction times obtained from the right and left hemispheres were similar in ECMO patients and were not different from those recorded from a group of patients suffering hypoxic-ischemic injuries and a group of normal controls who did not receive ECMO. The results of this pilot study suggest that SEPs may be employed to evaluate ECMO patients as they are in other brain-injured patients.

Adolescent↗
PubMed1995

Site-specific proteoglycan characteristics of third carpal articular cartilage in exercised and nonexercised horses.

The relevance of site and the influence of exercise on third carpal articular cartilage proteoglycan (PG) were assessed in 16 horses. Six horses were exercised (exercised group) for 30 minutes, 3 times/wk, for 6 weeks. The other 10 horses (nonexercised group) were housed in box stalls for the same 6-week period. At week 6, articular cartilage from the proximal surface of the right third carpal bone was harvested and cultured with radioactive sulfate to label newly synthesized PG. Endogenous PG was measured by use of a uronic acid assay. Newly synthesized and endogenous PG were characterized by use of Sepharose CL-2B chromatography, composite gel electrophoresis, and/or immunoblot analysis with monoclonal antibody 1C6 directed against the hyaluronic acid-binding region on PG. There was a significant (P = 0.0002) effect of exercise, but not site, on newly synthesized PG, which was increased in the exercised horses, compared with the nonexercised horses at the end of the 6-week study period. The increase in newly synthesized PG was not reflected in the existing cartilage matrix as there was no significant difference between groups in endogenous PG. However, there was a significant (P = 0.01) effect of site on endogenous PG, with the nest of sites located in the palmar aspect of the radial facet containing a greater concentration of endogenous PG than the nests of sites located on the dorsal aspect of the radial facet or all sites on the intermediate facet. Most newly synthesized PG in both groups consisted of hydrodynamically small PG monomers. However, there was a change in the profile of newly synthesized PG at some sites in the exercised horses to include an early elution peak on Sepharose CL-2B, which may contain aggregating PG. All sites in both groups contained a diverse population of endogenous large and small PG on toluidine blue-stained composite gels that reacted with monoclonal antibody 1C6, indicating the potential to bind to hyaluronic acid.

Animals↗
PubMed1994

Arthroscopic removal of osteochondral fragments from the proximal interphalangeal joint of the pelvic limbs in three horses.

Osteochondral fragments detected in the proximal interphalangeal joint in the pelvic limbs of 3 horses (2 Standardbreds and 1 Thoroughbred) caused joint enlargement and lameness. Fragments were removed by use of arthroscopy. Accurate placement of the arthroscope into the dorsal joint space was necessary to obtain an adequate view of the fragments. After surgery, 2 of the horses resumed racing without joint problems, and the third was in training to race. High-detail radiographs are necessary to detect osteochondral fragments in horses with joint enlargement or lameness localized to the proximal interphalangeal joint.

Animals↗
PubMed1994

A comparison of syringes to collect blood for analysis of gases, electrolytes and glucose.

We studied the interchangeability of two blood gas syringes (Johns, Hardie Health Care Products Pty Ltd and Marksman, Martell Medical Products Inc) for the collection of blood for the analysis of PCO2, PO2, pH, sodium, potassium and glucose in 71 intensive care unit patients. The interchangeability of these two syringes with a specially designed syringe (Radiometer, Radiometer A/S) for the collection of blood for the analysis of ionized calcium was also studied. Analysis of pH, sodium, potassium and glucose showed no clinically significant differences between samples collected with Johns and Marksman syringes. However, differences in PCO2 and PO2 in samples collected with these syringes may be clinically significant if the PO2 is less than 100 mmHg. There were no clinically significant differences in ionized calcium levels in blood samples collected with Johns, Marksman and Radiometer syringes. We conclude that Johns and Marksman syringes are interchangeable for the collection of blood for the analysis of PCO2, PO2, pH, sodium, potassium and glucose and they are also interchangeable with Radiometer syringes for the collection of blood for ionized calcium analysis.

Adolescent↗
PubMed1993

Assessment and treatment of equine humeral fractures: retrospective study of 54 cases (1972-1990).

Fractures of the humerus were diagnosed in horses at The Ohio State University Veterinary Teaching Hospital. Twenty-four horses (44.4%) were destroyed after radiographic assessment (mean age of 5.0 years). Surgical treatment was elected in 13 horses (24.1%, mean age of 0.42 years). Conservative management, consisting of prolonged stall rest, was chosen for 17 horses (31.5%, mean age of 2.2 years). In the surgically treated group, 3 foals (23.1%) all less than 2 months of age at the time of fracture and treated with intramedullary stack pinning, survived and became athletically sound. After conservative treatment, 9 (52.9%) horses were considered successful, 4 becoming athletically sound and 5 becoming pasture sound. The mean age at the time of presentation in the 9 horses considered successful was 1.81 years. With current fixation techniques, conservative management of equine humeral fractures appears to be as good an option as surgical treatment.

Age Factors↗
PubMed1992

The solution structure of echistatin: evidence for disulphide bond rearrangement in homologous snake toxins.

The solution structure of the fibrinogen antagonist, echistatin, has been determined by a combination of NMR and simulated annealing methods. While the structure of the disulphide-linked core is well-defined by the NMR data, the N- and C-termini and the loop bearing the RGD sequence (which is responsible for the fibrinogen antagonist properties) are poorly defined. The pattern of disulphide bridges, which could not be determined by classical methods, was predicted by a statistical analysis of the simulated annealing structures. This pattern is distinct from that for the homologous protein kistrin, leading to the novel suggestion that homologous proteins possess non-conserved patterns of disulphide bridges.

Amino Acid Sequence↗
PubMed1991

Nuclear magnetic resonance studies of the snake toxin echistatin. 1H resonance assignments and secondary structure.

The 1H-NMR spectrum of the snake toxin echistatin has been assigned using homonuclear two-dimensional methods. Consideration of the NOE patterns, coupling constants and putative hydrogen bonds enabled two regular features of secondary structure to be deduced: a beta-sheet/turn between residues 8 and 13 and a small anti-parallel beta-sheet and bulge linking residues 16-20 with residues 30-33. The recognition region of the protein containing the residues RGD lies in a loop joining the two strands of the beta-sheet. The beta-bulge and the loop containing the RGD sequence undergo pH-dependent conformational interconversion, modulated by the side chain of Asp29.

Amino Acid Sequence↗
PubMed1987

Induction of in vivo helper activity for murine antibody responses by macrophages pulsed with ovalbumin-monomethoxypolyethylene glycol (OA-mPEG) conjugates.

Conjugates of protein antigens with an optimal number of monomethoxypolyethylene glycol (mPEG) chains of an appropriate molecular weight had been shown to suppress murine IgE responses to the unmodified antigen. To investigate the possibility that the tolerogenic capacity of these mPEG conjugates is attributable to a defect in macrophage (M phi) presentation of their antigenic determinants, the activity of ovalbumin (OA)-mPEG conjugates when pulsed onto mouse peritoneal adherent cells (M phi) was compared in this study with their activity in solution. Surprisingly, in contrast to the suppressogenic capacity of mPEG conjugates in solution, the OA-mPEG pulsed M phi appeared to exert a helper effect when injected intraperitoneally (ip), i.e., after subsequent immunization with dinitrophenylated OA (DNP3-OA) in Al(OH)3, the mice showed accelerated IgE and IgG1 antibody responses to OA and DNP. However, when M phi were exposed to limiting concentrations of OA or OA-mPEG, markedly higher concentrations of OA-mPEG were required to yield pulsed M phi, exerting a significant helper effect. It was concluded that although M phi were capable of presenting the OA determinants of OA-mPEG conjugates to helper T (Th) cells, the preparations of modified antigen were presented less effectively than native OA.

Animals↗
PubMed1984

Studies on the mechanism of suppression of experimental allergic encephalomyelitis induced by myelin basic protein-cell conjugates.

The mechanism of suppression of experimental allergic encephalomyelitis (EAE) induced in Lewis rats by pretreatment with myelin basic protein (MBP) coupled to syngeneic spleen leukocytes (SL) was examined. Studies on the kinetics of the tolerance induction showed that pretreatment with MBP-SL suppressed EAE if given 7 but not 3 days before the disease-inducing injection of MBP in Freund's complete adjuvant. Treatment with cyclophosphamide 48 hr before administration of MBP-SL completely abolished the suppression of EAE. Transfer of lymph node and spleen cells from MBP-syngeneic erythrocyte conjugate (MBP-RBC) but not MBP-SL-pretreated rats resulted in suppression of disease in recipients subsequently given a disease-inducing injection of MBP. Administration of MBP coupled to SL from the histocompatible rat strain F344 resulted in suppression of the MBP-induced proliferative response of spleen cells from Lewis rats which had been given a disease-inducing injection of MBP. Taken together these results are consistent with the suppression of EAE induced by MBP-SL being mediated by suppressor T cells.

Animals↗
PubMed1984

Suppression of the anti-trimellityl (TM) IgE response in mice by conjugates of TM with polyvinyl alcohol.

The i.p. injection of 1 microgram of TM3-OA or TM9-OA with 1 mg of A1(OH)3 into B6D2F1 mice elicited the production of antibodies of the IgE and other classes to the trimellityl (TM) group and ovalbumin (OA). The induction of anti-TM antibodies belonging to the IgE and other immunoglobulin classes was specifically suppressed by the administration of tolerogenic conjugates prepared by coupling trimellitic anhydride (TMA) to the hydrophilic non-immunogenic polymer, polyvinyl alcohol (PVA), prior to immunization with TM-OA conjugates. More importantly, established anti-TM responses were also suppressed by these TM-PVA conjugates. By contrast, however, treatment with TM-PVA conjugates did not affect either the primary or the established anti-OA antibody response. The tolerogenic effects of the PVA conjugates were dose-dependent and appeared also to be dependent on the epitope density. Treatment with these conjugates also prevented immunized mice from showing any symptoms of systemic anaphylaxis on challenge with polyvalent TM-protein conjugates. These findings indicate that these conjugates may have the potential of useful therapeutic agents for the treatment of TMA-induced pulmonary hypersensitivity diseases.

Anaphylaxis↗
PubMed1983

The suppression of experimental allergic encephalomyelitis in Lewis rats by treatment with myelin basic protein-cell conjugates.

Pretreatment of Lewis rats with guinea pig (GP) myelin basic protein (MBP) coupled to syngeneic spleen leukocytes (SL) suppressed the subsequent induction of experimental allegic encephalomyelitis (EAE) with GP-MBP in Freund's complete adjuvant. The degree of suppression correlated positively with the amount of antigen coupled to the SL. GP-MBP coupled to syngeneic red blood cells (RBC) also resulted in suppression of EAE and the extent of the suppression was related to the dose of cells. These regimens of pretreatment also resulted in a decrease in the in vitro lymphocyte proliferative response to GP-MBP and in the extent of perivascular cuffing in the spinal cord. No decrease in the anti-MBP antibody response was detected in rats pretreated with either GP-MBP-SL or GP-MBP-RBC conjugates. Transfer of lymph node cells from rats pretreated with GP-MBP-RBC resulted in a decrease in disease severity in recipients. It is concluded that prior administration of MBP-cell conjugates is an effective way of suppressing the symptoms of EAE.

Animals↗