Biomedical subjects

R du Toit

Publications and source records attributed to R du Toit.

At least 19 recordsLinked to original sources

PubMed2006

A needs analysis for a non-abusive intervention programme in the School of Health Care Sciences at the University of Pretoria.

Due to feedback from students, student abuse during fieldwork, was brought to the attention of the researchers. The study aimed to determine whether a need for a non-abusive intervention programme (NIP) existed amongst the School of Health Care Science students at the University of Pretoria. All students enrolled at the School of Health Care Sciences completed a questionnaire. An overwhelming response indicated that the majority of students (95.85%) have a need for a non-abusive intervention programme (NIP). A significant need was identified especially among Nursing-, Physiotherapy- and Radiography students, 2nd and 4th year students, and within a psychiatric fieldwork setting. Two surprise findings were firstly, that students who have no history of abuse have a greater need for an intervention programme than students with a history of abuse. Secondly superiors in the field are responsible for the majority of abusive incidences reported by students. The implementation of a non-abusive intervention programme (NIP) to help students handle abusive incidences effectively and humanely is strongly recommended.

Allied Health Personnel↗

PubMed2001

Comparison of the antioxidant content of fruits, vegetables and teas measured as vitamin C equivalents.

Most of the health benefits of black, green and oolong teas made from Camellia sinensis are attributed to their antioxidant content. Many plants and spices have been used to make infusions that are erroneously referred to as 'teas'. The term 'rich in antioxidants' is often used to describe such infusions, often without scientific support. We have used the DPPH method to quantify the total radical scavenging capacity (RSC) of a wide range of 'teas', fruits and vegetables. The results are presented as vitamin C equivalents. These results are compared to the RSC of the recommended portions of fruits and vegetables in the food guide pyramid for a healthy and balanced diet. The EC(50) results show that there are no statistically significant differences in the RSC of black, green and oolong teas. However, the RSC of 'teas' made from other species of plants are significantly lower. Our results show that one or two cups of tea would provide a similar amount of RSC as five potions of fruits and vegetables or 400 mg vitamin C equivalents. This would be comparable to two capsules (200 mg) of vitamin C. Caution is advised in extrapolating these in vitro results to humans due to bioavailability.

Antioxidants↗

PubMed2001

Recovery from hyperemia after overnight wear of low and high transmissibility hydrogel lenses.

PURPOSE: To measure the limbal vascular response after 8 hours of eye closure while wearing high and low permeability lenses compared to control eyes without lenses. METHOD: Twenty neophyte participants wore lotrafilcon A silicone hydrogel lenses (HDk; Dk = 140) or etafilcon A hydrogel lenses (LDk; Dk = 18). On two different nights the lenses were randomly worn for 8 hours during sleep in the right eyes only. Left eyes were non-lens wearing controls. Biomicroscopic images of the temporal limbal area were videotaped at baseline, on eye opening and every 20 minutes for 3 hours. A masked observer graded digitized images of the limbal area. RESULTS: On waking and after lens removal there were no differences in hyperemia between the HDk and LDk lens wearing eyes. There were also no differences at any time between the HDk lens wearing eyes and their control eyes (p > 0.05). On waking the eyes wearing the LDk lens were more hyperemic compared to baseline (p < 0.001) and compared to their control eyes at 20 (p < 0.001) and 180 minutes (p = 0.01), indicating slower recovery from hyperemia. The HDk lens wearing eyes recovered to their baseline levels by 180 minutes (p = 0.99), compared to the LDk lens wearing eyes, which had not recovered to baseline levels by 180 minutes (p = 0.04). CONCLUSION: The reduction in hyperemia over time of the HDk lens wearing eyes was the same as the controls. The LDk lens wearing eyes were more hyperemic than the controls on waking and the reduction in hyperemia over time was slower. This suggests that the slower recovery from hyperemia may be affected by the lower oxygen transmissibility of the LDk lens.

Adult↗

PubMed2001

The effects of six months of contact lens wear on the tear film, ocular surfaces, and symptoms of presbyopes.

PURPOSE: To assess the tear film, ocular surfaces, and symptoms of ocular discomfort in a presbyopic population before and after contact lens wear. METHODS: A total of 150 presbyopes (49% were previous soft contact lens wearers) participated in a clinical trial in which they wore either monovision (single vision Acuvue lenses) or Acuvue Bifocal contact lenses. Clinical measurements of tear film, biomicroscopy, and corneal sensitivity as well as subjective ratings using the Dry Eye Questionnaire were collected at the initial visit and repeated after 6 months. Comparisons were made between age groups (40 to 51 years and 52 to 71 years) and genders before and after contact lens wear. Associations between objective and subjective tests were sought. RESULTS: After 6 months of contact lens wear, clinical signs had worsened by less than one-half of a grade, and tear break up time (TBUT) worsened by 3 s. Only TBUT was lower for the older age group. Females had less bulbar hyperemia, more sensitive eyes, more lissamine green staining, and lower TBUT and phenol red thread measurements (all p < 0.04). Twenty-eight percent experienced dryness before contact lens wear, but this figure increased to 68% when wearing contact lenses. There were no age differences, but almost twice as many females as males reported dryness. Reporting symptoms of dryness was associated with gender, corneal sensitivity, and type of corneal staining. CONCLUSIONS: These results provide a representation of the ocular surface condition and symptoms of ocular discomfort in the middle-aged population and seem similar to reports of younger populations. Wearing contact lenses seems to influence dry eye symptoms more than age or gender. Therefore, presbyopes should not be excluded from consideration for contact lens fitting.

Adult↗

PubMed1999

Sympathetic swelling response of the control eye to soft lenses in the other eye.

PURPOSE: To compare central corneal swelling and light scatter after 8 hours of sleep in eyes wearing high- and low-Dk hydrogel lenses and to the contralateral control eyes. METHODS: Twenty neophyte subjects wore a Lotrafilcon A (Dk, 140; Ciba Vision, Duluth GA) silicone hydrogel lens and an Etafilcon A (Dk, 18; Acuvue; Vistakon, Jacksonville, FL) 58% water content hydrogel lens of similar center thickness in random order in the right eye only, for overnight 8-hour periods. The contralateral nonwearing left eyes served as controls. Central corneal thickness was measured using an optical pachometer and light scatter using a Van den Berg stray-light meter before lens insertion, after lens removal on waking, and every 20 minutes for the next 3 hours. RESULTS: Central corneal swelling induced by the Etafilcon A lens on eye opening was significantly higher than with the Lotrafilcon A lens (8.66%+/-2.84% versus 2.71%+/-1.91%; P<0.00001). Light scatter induced by the Etafilcon A lens on eye opening was significantly higher than with the Lotrafilcon A lens (46.09+/-5.62 versus 42.78+/-6.07 Van den Berg units, P = 0.0078). The swelling of the control eyes paired with the Etafilcon A lens-wearing eyes was also slightly but significantly higher than that of the control eyes paired with the Lotrafilcon A lens-wearing eyes (2.34%+/-1.26% versus 1.44%+/-0.91%; P = 0.0002). Light-scatter measurements were not significantly different between control sets of eyes but showed the same trend. CONCLUSIONS: In neophyte subjects, corneal swelling of the contralateral control eyes appears to be influenced by the swelling of the fellow lens-wearing eyes-that is, the swelling of the contralateral control eye was significantly lower when there was less swelling of the fellow eye wearing the high-Dk lens. Although there was no statistically significant difference in light-scatter measurements between the control sets of eyes, a trend similar to the corneal swelling results was observed, which could be used to support the suggestion that this may be a sympathetic physiological response rather than an unusual sampling coincidence.

Adult↗

PubMed1998

Visual and nonvisual variables implicated in monovision wear.

BACKGROUND: Although both psychological and visual factors have been suggested to influence successful monovision contact lens wear, there has not been any documentation to support the relationship between psychological factors and the outcome of monovision wear. In our study, the relative importance of various visual and psychological factors were investigated in an attempt to provide a profile of a successful monovision wearer. METHODS: Participants, who had never worn monovision lenses were fitted with distance contact lenses for an adaptation period of 2 weeks; thereafter, 67 participants wore monovision lenses for 2 weeks. RESULTS: Of the participants, 67% stated that based on their visual experience they would continue monovision wear. Discriminant analysis indicated that one of the personality factors in Cattell's 16 Personality Factor (16 PF) test, "superego strength," could be used, in conjunction with the difference between binocular and monovision stereopsis scores, in predicting the success of monovision in 68% of the cases. The variables of age, gender, pupil size, immediate reaction to monovision, motivation, self-efficacy distance, and near refractive error could not be used to predict successful monovision wear. CONCLUSIONS: These result demonstrate that psychological factors are indeed important in monovision wear.

Adaptation, Ocular↗

PubMed1993

Empirical evaluation of conditions influencing the polymerase chain reaction: enterotoxigenic Escherichia coli as a test case.

False polymerase chain reaction (PCR) results may be obtained under unfavourable reaction conditions. Therefore optimal conditions for the different factors influencing a specific PCR method should be determined before introduction to a clinical diagnostic laboratory. This study has concentrated on the detection of heat-labile enterotoxin-producing E. coli by PCR, with empirical evaluation of various factors. Template was prepared by heat-lysis of E. coli, and this was shown to be adequate for PCR detection. The results showed that deviation from the optimal conditions of any of the following conditions may lead to false results: lysis of bacterial cells, denaturation temperature during cycling, annealing temperature, primer concentration, enzyme concentration, magnesium concentration and ion concentration. Three different detection methods for PCR product were also evaluated. As little as one bacterium can be detected after 35 cycles of PCR amplification with 32P-labelled oligonucleotide probe. An alkaline phosphatase-labelled probe was 10-fold less sensitive, whereas 100 bacteria in 10 microliters of the original sample suspension were necessary to give a positive signal after gel electrophoresis. The information in this study may be useful to those who wish to introduce PCR tests to diagnostic laboratories.

Bacterial Toxins↗

PubMed1993

Laboratory experience and guidelines for avoiding false positive polymerase chain reaction results.

Despite the widespread use of polymerase chain reaction (PCR) for diagnosis of infectious diseases, the technology has not been generally introduced into routine diagnostic laboratories. One of the most serious problems which has influenced the acceptance of this technology is the occurrence of false positive PCR results. This study describes the experience, in a hospital laboratory setting, of using PCR for the diagnosis of heat-labile enterotoxin-producing E. coli, M. tuberculosis, M. paratuberculosis and human papillomavirus. Results indicate that a build-up of amplicons, generated during the amplification process in the laboratory, is the main source of PCR-contamination. Protocols are described that include both physical and chemical procedures to prevent contamination. The use of photo-induced psoralen is recommended for those laboratories already involved in PCR work where amplicons are likely to be present. An enzymatic system (uracil-N-glycosylase) was evaluated and is recommended for workers intending to start diagnostic PCR. Attention was given to simple control measures which are easily implemented in a routine diagnostic laboratory. Protocols such as these are likely to have a major impact on the introduction of PCR-based methods into routine laboratories.

Bacteria↗

PubMed1992

Purification of sputum samples through sucrose improves detection of Mycobacterium tuberculosis by polymerase chain reaction.

A method is described for the routine preparation of sputum samples for detection of Mycobacterium tuberculosis by using polymerase chain reaction amplification. Liquefaction of sputum samples with NaOH and subsequent removal of inhibitors of the polymerase reaction with a 50% sucrose centrifugation step (5 min) in a desktop centrifuge allow direct amplification of a 123-bp repetitive region of the M. tuberculosis genome. We have evaluated the sensitivity and specificity of the sucrose method with 155 sputum specimens from patients suspected of having tuberculosis and from normal healthy volunteers. This method, in our opinion, is reproducible, sensitive, and reliable. Multiple samples can be handled simultaneously, and results can be obtained in one working day.

Centrifugation, Density Gradient↗

PubMed1991

Improved method for the routine identification of toxigenic Escherichia coli by DNA amplification of a conserved region of the heat-labile toxin A subunit.

This report describes a DNA amplification procedure for routine identification of heat-labile-toxin-producing Escherichia coli. Two oligonucleotide primers were used in a polymerase chain reaction procedure to amplify a highly conserved region of the A subunit of the heat-labile enterotoxin gene. Amplifications were done directly on E. coli colonies from plates when Salmonella, Shigella, or parasite infections were excluded as agents of the severe diarrhea in the patients. The conditions for the polymerase chain reaction method were empirically determined, and the procedure is inexpensive, sensitive, and specific. Positive results can be obtained over a wide variation in bacterial numbers, with no inhibition of Thermus aquaticus DNA polymerase. Detection of the amplified product can be done by agarose gel electrophoresis, which is specific and sensitive enough for routine diagnosis of this pathogen in clinical isolates. If greater sensitivity and specificity are required, hybridization with 32P- or alkaline phosphatase-labeled oligonucleotide probes can be used. Our results suggest that heat-labile-toxin-producing E. coli is responsible for about 9% of nondiagnosed diarrhea cases in Tygerberg Hospital, Tygerberg, Republic of South Africa.

Alkaline Phosphatase↗

PubMed1990