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Biomedical subjects

C Chambers

Publications and source records attributed to C Chambers.

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

A comparison of antioxidant enzyme activities in organ-cultured rhesus monkey lenses following peroxide challenge.

PURPOSE: To analyze the activities of catalase, glutathione peroxidase and superoxide dismutase, three enzymes involved in the detoxification of reactive oxygen species in organ-cultured Rhesus monkey lenses. METHODS: Lenses freshly obtained from Rhesus monkeys were incubated at 37 degrees C for 2 h and assessed for lens integrity. Lenses were then oxidatively stressed by exposure to a bolus of hydrogen peroxide. The three enzyme activities were assayed 2, 4 and 24 h after exposure to the peroxide challenge. RESULTS: Freshly dissected lenses placed in organ culture exhibited a 20% decrease in catalase activity within 2 h. During the course of a 24 h incubation, catalase activity continued to decrease to a level 58% below that of freshly dissected monkey lenses. In contrast, the activity levels of both glutathione peroxidase and superoxide dismutase increased dramatically within the first 2 h of organ culture, with superoxide dismutase being most affected. Although glutathione peroxidase activity declined with incubation time, its level at the end of 24 h was still 36% greater than that of the fresh lenses. Superoxide dismutase activity remained elevated throughout the 24 h incubation period. The addition of a bolus of 0.25mM H2O2 to monkey lenses in culture had no effect on catalase activity. Two h after the peroxide insult, glutathione peroxidase activity decreased in comparison to control levels while the activity of superoxide dismutase increased by 43%. After 24 h, superoxide dismutase activity returned to values equivalent to the controls. In lenses challenged with 0.50mM H2O2, catalase and glutathione peroxidase activities decreased at 2 h, while superoxide dismutase activity increased 67% above control levels. At subsequent timepoints, catalase activity increased and reached control levels. In contrast, glutathione peroxidase activity continued to decrease with time eventually reaching fresh lens levels. Superoxide dismutase activity levels remained elevated and were equivalent to control values at 24 h. CONCLUSIONS: The data indicate that placement of monkey lenses into an organ culture system represents an environmental change sufficient to cause a response in antioxidant enzyme levels. The addition of H2O2 to this environment caused only superoxide dismutase to be stimulated above control lens levels.

Animals↗
PubMed1996

Community-oriented primary care in a family practice residency program.

BACKGROUND: The practice of medicine needs to include disease prevention, health promotion, community health, and clinical epidemiology. Community-oriented primary care (COPC) can be used as an educational strategy to develop competencies in these areas. METHODOLOGY: An interdisciplinary team that included public health representatives was created to teach COPC principles to family practice residents and supervise their community projects. Allied health and nursing graduate students were also involved in the process. Projects were implemented in collaboration with community representatives. RESULTS: Family practice residents and community representatives were positive about working together. The family practice residents appreciated the interdisciplinary experience and reported that the COPC model will be useful to them in the future. However, the program's didactic phase was insufficient to provide adequate skills for use of the COPC process. The program could benefit from more involvement of medical students and students in other health professions. CONCLUSIONS: The program encountered several significant obstacles such as competing clinical priorities, limited health education skills, and inadequate project evaluations. Despite the challenges, the family practice residents, as well as the interdisciplinary faculty, health science graduate students, and community representatives, reported a positive experience.

Clinical Competence↗
PubMed1995

Sequence, initial functional analysis and protein-DNA binding sites of the mouse beta B2-crystallin-encoding gene.

An 800-bp fragment of genomic DNA upstream from the origin of transcription of the mouse beta B2-crystallin-encoding gene (beta B2-Cry) has been isolated and its nucleotide sequence determined. Promoter fragments 275 to +30 or -110 to +30, fused to cat reporter gene, activated transcription in transiently transfected rabbit lens epithelial cells, but not in various non-lens cells. The beta B2-Cry mouse promoter contains a typical TATA-box located approx. 25 bp upstream from the transcription start point. Binding sites (upstream from the TATA-box) for transcription factors possibly involved in the regulation of gene expression have been identified by DNaseI footprinting analysis and lens cell nuclear extracts. Most notably is the binding of the Pax-6 paired domain (PrD) which correlates with the binding of lens cell nuclear proteins at the -80 to -40 region.

Animals↗
PubMed1995

A national survey of admissions criteria and processes in selected allied health professions.

A national survey of admissions criteria and procedures was conducted for allied health programs in diagnostic medical imaging, health information management, nurse-midwifery, occupational therapy, physical therapy, and physician assistant education. From a sample of 462, 63.2% responded. The survey canvassed general program information, prerequisites, admissions procedures, and demographic trends. Respondents were primarily from public institutions with faculty actively involved in admissions. The most common prerequisites were anatomy/physiology, physics, biology, chemistry, and psychology; and the most frequently required admissions criteria were GPA, references, interviews, science GPA, and writing sample. Standardized tests were rarely utilized. The following were the major prerequisite characteristics and skills considered: academic skills, communication skills, problem-solving abilities, maturity/confidence, motivation, and work/study habits. Changing demographics were reported, including an increase in second-career, older, and ethnically diverse applicants. Also discussed were nontraditional and minority applicant admissions issues. Future research suggestions include use of noncognitive variables, and academic and clinical outcome studies. The utility of this information for validation/revision of admissions criteria are presented.

Allied Health Personnel↗
PubMed1994

Gas exchange of captive freely diving grey seals (Halichoerus grypus).

When at sea, phocids dive for long periods and spend a high percentage of their time submerged. This behaviour requires some combination of an increased oxygen storage capacity, rapid oxygen loading at the surface and reduced oxygen utilisation when submerged. To assess these adaptations, breath-by-breath ventilation was studied in four adult grey seals (two male, two female, 160-250 kg), freely diving in a large outdoor tank where surface access was restricted to one breathing hole. The dive patterns obtained were similar to those recorded from freely diving wild grey seals. Respiratory frequency during the surface periods was 40% higher than that estimated from allometric relationships (19.4 +/- 0.7 breaths min-1), and tidal volume (6.3 +/- 1.21) was approximately five times higher than that estimated from allometric relationships. These adaptations produce a high minute volume and enable gas exchange to occur at the surface. Mean oxygen consumption rate (VO2, measured for a dive+surface cycle) decreased with increasing dive duration. The aerobic dive limit was estimated as 9.6 min for a 150 kg grey seal (using the overall average VO2 of 5.2 ml O2 min-1 kg-1), which is consistent with results from freely diving wild grey seals (only 6% of dives exceeded 10 min). End-tidal oxygen values varied during a surface period, following a U-shaped curve, which suggests that there is limited oxygen uptake from the lung and/or blood oxygen stores during dives. This result was unexpected and indicates that these seals are utilising substantial physiological responses to conserve oxygen, even during shallow voluntary diving.

Animals↗
PubMed1993

Sequence of the human lens beta B2-crystallin-encoding cDNA.

This study reports the nucleotide (nt) sequence of the human beta B2-crystallin (h beta B2-Cry)-encoding cDNA (h beta B2-cry). The h beta B2-cry gene encodes a major structural protein in the lens of the vertebrate eye. Sequence information obtained from mouse genomic clones and the mouse beta B2-cry cDNA (m beta B2-cry) sequence was used to design oligodeoxyribonucleotide primers, corresponding to exon 1, transcription start points, and termination and polyadenylation sites, that were used in the polymerase chain reaction (PCR) to generate full-length cDNA clones from total human lens RNA. In addition, cDNA libraries were made with lambda gt11 from both human fetal and adult lens tissue RNAs, and screened with a m beta B2-cry cDNA clone. The full-length h beta B2-cry cDNA is 721 bp and contains an open reading frame of 612 nt. It codes for a 23-kDa protein of 205 amino acid residues. Comparison of the overall nt and deduced aa sequences shows a greater similarity of h beta B2-cry to bovine beta B2-cry than to m beta B2-cry or rat beta B2-cry.

Adolescent↗
PubMed1993

Dosing efficiency and particle-size characteristics of pressurized metered-dose inhaler aerosols in narrow catheters.

An experimental in vitro model was used to determine the effects of intraluminal catheter diameter and length on the delivered dose and particle-size characteristics of salbutamol (albuterol) aerosol delivered by metered dose inhaler (MDI) (Ventolin, 100 micrograms per puff). The dose of aerosolized drug that exited a 16-cm-long tracheal tube with an inner diameter (ID) of 6 mm was compared with that from 4 catheters of differing diameters and lengths that were inserted individually into the tracheal tube. The salbutamol MDI canister was actuated ten times into each delivery system, and the effluent aerosol was trapped onto a filter. The filtrate was dissolved in methanol, and the salbutamol concentration was determined using high-performance liquid chromatography. For the 3 22-cm-long catheters, the delivered dose (mean +/- SD) of salbutamol per actuation for the 22-standard wire gauge (SWG) catheter was 97.5 +/- 3.9 micrograms, which was similar to that for the 19-SWG catheter (102.3 +/- 2.5 micrograms) but was significantly less than that for the 14-SWG catheter (108.2 +/- 4.2 micrograms) (p < 0.05). These delivered doses exceeded those of the 6.0-mm-ID tracheal tube alone (2.33 +/- 0.76 micrograms) and the 13-cm-long 19-SWG catheter (2.17 +/- 0.29 micrograms) (p < 0.001). In a second experiment using a cascade impactor, the distribution of aerosol particle diameters that exited the 6-mm-ID tracheal tube was compared with that exiting a 13-cm-long 19-SWG catheter that extended halfway down the tracheal tube and with that exiting a 22-cm-long 19-SWG catheter inserted into the distal end of the 6-mm-ID tracheal tube. The mass median aerodynamic diameter (mean +/- SD) of the salbutamol aerosols delivered through both the 6.0-mm-ID tracheal tube (1.1 +/- 0.1 microns) and that of the 13-cm-long 19-SWG catheter (1.2 +/- 0.2 microns) were significantly less than that delivered through the 22-cm-long 19-SWG catheter (2.0 +/- 0.1 microns) (p < 0.05). The authors conclude that delivery of respirable aerosol can occur through narrow catheters that function as extended nozzles for MDIs. Optimal dosing will be obtained when the catheter extends the full length of the tracheal tube.

Aerosols↗
PubMed1992

The effect of fetal sepsis on umbilical cord blood gases.

The relationship between fetal sepsis and acid-base status is unknown. We hypothesized that in utero sepsis would result in fetal metabolic acidemia. In a retrospective study during a 38-month period, the acid-base status at birth of neonates with in utero sepsis, documented by positive blood cultures, was reviewed. Compared with term neonates, preterm neonates had a 22-fold increase in the risk of bacteremia at birth. In spite of this increased risk of sepsis, there was no significant alteration in arterial pH in preterm septic neonates when compared with preterm controls. Fetal sepsis at term was accompanied by a statistically significant reduction in arterial pH (7.21 +/- 0.07) compared with controls (7.26 +/- 0.06, p less than 0.05). When controlled for other variables, the decrease in arterial pH at term was correlated with an increased duration of labor (7.3 +/- 0.7 in controls vs 10.8 +/- 0.9 hours in neonates with sepsis, p less than 0.05). The classic predictors of chorioamnionitis were found to be poor prognostic indicators of fetal bacteremia. Fetal sepsis at term is associated with a deterioration in the fetal acid-base status and a prolongation of labor.

Acid-Base Equilibrium↗
PubMed1992

Ciliary function, cell viability, and in vitro effect of ribavirin on nasal epithelial cells in acute rhinorrhea.

Nasal epithelial (NE) cells were collected from the nasopharynx of 25 individuals with symptomatic colds and 27 healthy volunteers (controls), and ciliary beat frequency (CBF) was assessed by microscopy employing video motion analysis techniques. Baseline CBF was statistically significantly elevated in the group with colds compared to the control group (14.6 +/- 1.5 Hz [mean +/- SD] vs 13.8 +/- 0.9 Hz; p = 0.02). After four days of incubation in culture, there was a significant decrease in the CBF in both groups, with a change from baseline of 1.9 Hz for the cold group, compared to 1.0 Hz for the control group (p = 0.0001). The in vitro addition of ribavirin at 500 micrograms/ml to NE cells from individuals with colds preserved the viability of the cells and maintained the CBF at baseline values. Twenty-four (96 percent) of 25 ribavirin-treated specimens from the cold group survived for four days in culture, compared with 17 (68 percent) of 25 untreated cold specimens. In addition, the ribavirin-treated cells had a mean CBF of 14.2 +/- 1.3 Hz, compared with 12.7 +/- 1.9 Hz for the untreated cell samples (p = 0.0005). Ribavirin had no effect on NE cells from the control group. These results suggest that ribavirin in a concentration of 500 micrograms/ml may have some benefit in the treatment of acute rhinorrhea.

Acute Disease↗
PubMed1991

Deletion mutation in an eye lens beta-crystallin. An animal model for inherited cataracts.

The most prevalent proteins in the lens of the eye are called crystallins, and it is thought that aberrant crystallins may cause opacification of lens tissue. The Philly mouse, a strain with an inherited cataract, has an abnormal beta B2-crystallin, the principal beta-crystallin in the mouse. The cDNA that codes for the beta B2-crystallin protein has been cloned and sequenced from both the normal and the cataractous Philly mouse. The normal mouse beta B2 cDNA is 756 nucleotides in length with 618 nucleotides of open reading frame. An in-frame deletion of 12 nucleotides has occurred in the Philly mouse cDNA, which results in the loss of 4 amino acids. The sequence of the mutant beta B2 was analyzed against the reported structure of the normal bovine beta B2-crystallin determined by x-ray crystallography. The region, in which the deletion of the amino acids occurs near the COOH terminus, is essential for the formation of the tertiary structure of the beta B2-crystallin. The loss of these residues could explain the alterations that are seen with the Philly beta B2 protein and may account for the instability of the Philly beta B2 protein. This abnormal beta B2-crystallin may be the cause of the cataract in this animal.

Amino Acid Sequence↗
PubMed1990

Sequence and structure correlation of human ribosomal transcribed spacers.

We report the sequences of the transcribed spacers of human rRNA that now allow us to piece together the entire primary transcript sequence of approximately 13.3 x 10(3) base-pairs. Comparison of transcribed spacer sequences with those of variable regions of rRNA and with those of the non-transcribed spacers supports the hypothesis that the variable regions are descended from transcribed spacers. Nucleotide sequence-derived secondary structures for the 5' external transcribed spacer and for internal transcribed spacers 1 and 2 match both the sizes and shapes of the structures that were visualized 15 years ago on electron micrographs. Parts of these structures are conserved in mammals and may be related to transcript processing.

Animals↗
PubMed1990

Interaction of an altered beta-crystallin with other proteins in the Philly mouse lens.

An altered beta B2-crystallin is synthesized in the lens of the Philly mouse. This beta B2 has a more acidic isoelectric point than the beta B2 that is isolated from normal mouse lens. The altered beta B2 is immunologically reactive with antibody to the amino terminal of the beta B2-crystallin, but appears to be present in only very small quantities in the Philly lens. When the soluble proteins are isolated from the Philly lens and chromatographed by gel exclusion chromatography, the beta B2 can be found primarily in the heavy molecular weight fraction. Some immunoreactive material was also found throughout the higher molecular weight beta-crystallin region, beta H, and the lower molecular weight region, beta L. These results would indicate that the altered beta B2-crystallin in the Philly lens can interact with the other beta-crystallins in the lens; however, interactions of the beta B2-crystallin with the other proteins of the lens may cause rapid aggregation of the cellular proteins leading to the formation of the heavy molecular weight material. The increased number of these aggregates may eventually lead to the cataract formation in the Philly mouse.

Animals↗