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Biomedical subjects

A D Steele

Publications and source records attributed to A D Steele.

At least 91 records · Page 5Linked to original sources
PubMed1993

A comparison of low dose methotrexate bioavailability: oral solution, oral tablet, subcutaneous and intramuscular dosing.

OBJECTIVE: To compare the relative bioavailability of low dose methotrexate (MTX) administered as tablet, oral solution, and subcutaneous (sc) injection to that of intramuscular (im) injection in patients with rheumatoid arthritis (RA). METHODS: Twelve patients meeting the American College of Rheumatology criteria for RA had serial blood MTX concentration samples drawn over a 24-h period after receiving their normal weekly MTX dose. Relative bioavailability (F) of the tablet and oral solution formulations was determined by comparison of the area under the time-versus-serum-concentration curves (AUC) for the 2 different oral formulations as a percentage of the AUC for im injection. Also, relative bioavailability of the sc formulation was compared to im in 6 of the patients. RESULTS: Mean F for the oral tablet was 0.85, while that for the oral solution was 0.87. Both oral formulations showed a statistically significant difference in mean F when compared to im (tablet vs im, p = 0.002, oral solution vs im, p = 0.009). No statistically significant difference, however, was found in mean relative bioavailability between tablet and solution (p = 0.744). The mean F for sc was 0.97; no statistically significant difference existed between the mean F values for the sc and im routes of administration (p = 0.657). CONCLUSIONS: Our data suggest the oral solution may be substituted for tablet dosing and sc injection substituted for im. Thus, a variety of different dosing methodologies may be considered providing the most appropriate route in each patient, given issues of compliance, medication cost, and preference.

Administration, Oral↗
PubMed1993

The microbial aetiology of summer paediatric gastroenteritis at Ga-Rankuwa Hospital in South Africa.

Stool material from seventy-eight children below the age of three years was examined for the presence of various enteropathogens. The patients had been admitted to the Ga-Rankuwa hospital for rehydration therapy. A causative agent was identified in 76.9% of the cases studied. The most prevalent organisms identified were 38.5% entero-toxigenic Escherichia coli (ETEC), 25.6% Cryptosporidium parvum, 15.4% Campylobacter sp., 14.1% enteric adenoviruses and 12.8% rotavirus. In 38.5% of cases, a mixed infection was observed with up to four different organisms being identified from a single patient. ETEC elaborating heat-labile toxin (LT) found together with C. parvum was the most common combination seen in mixed infections.

Child, Preschool↗
PubMed1992

Further characterisation of human rotaviruses isolated from asymptomatically infected neonates in South Africa.

Stool specimens were collected from healthy neonates at Ga-Rankuwa Hospital in the winters of 1984 and 1986 and tested for the presence of rotavirus infection. Asymptomatic excretion was found to occur in 25% of the newborn babies analysed. Gel electrophoresis of the rotavirus RNA genome revealed that a genomically stable strain of rotavirus was endemic in the ward at the time intervals examined. Hybridisation analysis of the VP4 and VP7 rotavirus genes, which encode the outer capsid neutralization proteins of the virus, was conducted. These results showed the presence of a serotype 4 rotavirus strain with an M37-like VP4 gene allele, which remained conserved in the nursery over the time period examined. Partial nucleotide sequences were obtained for a variable region of the VP7 gene and for the hyperdivergent region of the VP4 gene from 8 of these viruses and showed that remarkable conservation of these regions in the genes of the viruses occurred over time.

Base Sequence↗
PubMed1992

The molecular epidemiology of rotavirus-associated gastro-enteritis in the Transkei, southern Africa.

Rotaviruses were detected in 32.8% (71/216) of stool specimens collected from young children with gastro-enteritis attending the Rehydration Unit at Umtata General Hospital between April 1988 and March 1989. A seasonal distribution was observed with an increase in numbers shedding the virus during the colder months of the year. Based on variations in the migration pattern of the RNA genome segments when passed through polyacrylamide gels, 14 different electrophoretypes were identified: 69% were long patterns and 27% were short patterns. A single dominant long electrophoretype persisted throughout the 12-month study period, whereas 13 other minor types co-circulated at varying intervals. Mixed infections were observed in three cases, including one infant who was infected with both a long (Wa-like) virus and a short (DS-1-like) virus.

Child, Preschool↗
PubMed1992

Radial keratotomy: a review of 300 cases.

Three hundred consecutive cases of radial keratotomy performed between 1985 and 1990 were reviewed. There were no sight threatening complications of surgery and no patient lost one or more lines of corrected Snellen acuity. Overall 78.7% saw 6/12 or better unaided postoperatively and 51.7% saw 6/6 or better. Refraction showed 61.3% to be within 1 dioptre of emmetropia and 86.7% were within 2 dioptres. Further analysis demonstrated that results of unaided acuity and proximity to emmetropia were much better for low (< -2.87 D) and moderate (-3.0 to -5.87 D) than for high (> -6.0 D) myopes.

Adult↗
PubMed1992

Coexistent corneal disease and glaucoma managed by either drainage surgery and subsequent keratoplasty or combined drainage surgery and penetrating keratoplasty.

The results of penetrating keratoplasty following trabeculectomy in 26 eyes where there was coexistent corneal disease and glaucoma are presented. Patients were aged 16-80 years at the time of drainage surgery (mean = 51 years) and there was a mean of 33.5 months between trabeculectomy and keratoplasty. The mean pressure fell from 35.3 mm Hg prior to trabeculectomy to 14.9 mm Hg at the time of keratoplasty and 20 mm Hg 12 months after keratoplasty. There was a 0.45 probability of maintaining normal intraocular pressure with medication at 5 years after keratoplasty; and a similar graft survival probability. The probability of maintaining both a clear graft and a normal pressure was only 0.27 at 5 years. In another 22 eyes combined trabeculectomy and penetrating keratoplasty was performed. Patients' ages ranged from 21-82 years (mean 55) at surgery, and 73% were aphakic. The intraocular pressure dropped from a mean of 28.9 mm Hg preoperatively to 14 mm Hg at 12 months. There was a 5 year probability of 0.7 of maintaining a clear graft but if both a clear graft and normal intraocular pressure are considered then the probability falls to 0.5 at 5 years. The hazard ratio for intraocular pressure control and graft survival between the two groups suggests that combined surgery may offer a better prognosis.

Adolescent↗
PubMed1992

Subgroup and serotype epidemiology of human rotaviruses recovered at Ga-Rankuwa, southern Africa.

This study analysed human rotaviruses isolated in Ga-Rankuwa, South Africa, using monoclonal antibodies directed at the subgroup-specific and serotype-specific antigens of the virus. The subgroup could be determined for 73pc of the specimens. Subgroup II viruses occurred more commonly than subgroup I viruses (77pc vs 22pc). A serotype specificity could be assigned in 65pc of cases with three serotypes observed to be circulating in this population. Serotype one strains were identified most commonly (43pc) with serotype two (12pc) and serotype four (9pc) strains also present. No serotype three strains were detected. One strain was identified which reacted with both subgroup I and II monoclonal antibodies and with serotype one and two monoclonal antibodies. This study highlights the unpredictable nature of the emergence of new serotypes and importance of surveillance of human rotavirus infection in this sub-continental region.

Antibodies, Monoclonal↗
PubMed1992

The molecular epidemiology of rotavirus infection in Ga-Rankuwa, southern Africa.

Rotaviruses were detected in 32.8 pc (96/292) of stool specimens collected from infants and young children with gastroenteritis attending the rehydration unit at Ga-Rankuwa Hospital between January and December 1989. A seasonal distribution was observed with an increase in numbers shedding the virus during the colder months of the year. Based on variations in the migration pattern of the RNA genome segments when passed through polyacrylamide gels, seven different RNA electrophoretypes were identified; 82 pc of the patients had virus with long patterns and 17 pc with short patterns. A mixed infection was observed in one case with both a long and a short virus. A single dominant long electrophoretype persisted throughout the 12 month study period, whereas the other minor types co-circulated at varying intervals.

Child, Preschool↗
PubMed1991

Shift in genomic RNA patterns of human rotaviruses isolated from white children in South Africa.

The molecular epidemiology of rotavirus infection in white children in Pretoria was investigated over a 2-year period. Rotavirus-positive specimens from 322 infants and young children submitted to private pathology laboratories were analysed by polyacrylamide-gel electrophoresis of the viral RNA. A predominance of long RNA profiles occurred and a temporal shift in the genomic patterns was identified. An epidemic of the classic shorter RNA profiles (suggestive of sub-group I rotaviruses) was observed in the winter of 1987, although these viruses were found less frequently than the sub-group II isolates (with a long RNA profile). Most neonatal isolates of rotaviruses exhibited a similar RNA electrophoretype, indicating that this strain of rotavirus was nosocomially acquired in different maternity units in the city.

Child, Preschool↗
PubMed1991

Refractive surgery for graft-induced astigmatism after penetrating keratoplasty for keratoconus.

Of a series of 201 corneal transplants for keratoconus over a 20-year period, 42 grafts (39 eyes of 38 patients) required further surgery because of intolerable astigmatism (range, -3 diopters [D] to -18 D; mean, 8.9 D). Relaxing incisions, compressive resuturing, and augmented relaxing incisions were the techniques used. All procedures resulted in a similar mean reduction in cylinder -3.6 to 5 D, but the outcome with augmented relaxing incisions was less predictable. Six grafts required two or more procedures for a satisfactory outcome. All patients had corrected visual acuity of 20/30 or better after surgery, and 75% had visual acuity of 20/20 or better. The cumulative time until 90% of the grafts had useful vision was 32 months after refractive surgery. Relaxing incisions offer the prospect of more rapid visual rehabilitation than compressive resuturing.

Astigmatism↗
PubMed1991

Is raised intraocular pressure a bad prognostic sign in acute corneal graft rejection?

One hundred and forty acute corneal rejection episodes in 94 patients were studied retrospectively. Sixteen episodes in 15 eyes were associated with raised intraocular pressure (IOP) on admission, three of whom had had previously elevated IOP. At six weeks, six (37.5%) still required hypotensive therapy. Five eyes with raised IOP at rejection had lost vision at six weeks. Five of the six eyes with graft failure at review had raised IOP either pre-graft, at rejection or at follow-up. Eyes grafted for herpes simplex keratitis with hypertensive rejection episodes had a higher mean admission IOP, with a more short-lived rise than other eyes.

Adult↗
PubMed1991

The role of penetrating keratoplasty in the management of microbial keratitis.

Penetrating keratoplasty was performed as an emergency procedure in 52 eyes which had perforated from acute microbial keratitis and in a further 11 where perforation had not yet occurred. The results are compared with those of keratoplasty in 33 non-infected perforations and 20 eyes where there had been microbial keratitis which had responded to medical therapy leaving a scarred cornea. This latter group had both a better five year survival (90%) compared to all the others (51%), p less than 0.05, and achieved significantly better visual acuities, p less than 0.005.

Graft Survival↗