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A D Steele

Publications and source records attributed to A D Steele.

At least 55 records · Page 3Linked to original sources
PubMed1997

Comparison of electron microscopy, enzyme-linked immunosorbent assay and latex agglutination for the detection of bovine rotavirus in faeces.

The performance characteristics of 2 enzyme immunoassays (ELISAs) and 4 latex agglutination assays (LXs) were evaluated for the detection of bovine rotavirus in faecal specimens of young calves with diarrhoea. A total of 26 specimens from calves less than 5 months of age were examined with different commercial assays and compared with electron microscopy (EM) as the gold standard and with polyacrylamide gel electrophoresis (PAGE) for the detection of atypical, non-group A rotaviruses. In the 2nd study, EIA (Dako) and LX (Murex), the assays of choice, were used to analyse 97 further faecal specimens from calves with diarrhoea. The ELISAs proved to be the most sensitive compared with the other tests used. The EM and PAGE are 100% specific although slightly less sensitive than the commercial assays. The results show that all the commercial assays can accurately detect rotavirus in the stools of calves with gastroenteritis, although the suitability and choice of assay will depend upon the requirements of individual laboratories.

Animals↗
PubMed1997

Snow mountain-like virus identified in young children with winter vomiting disease in South Africa.

Human caliciviruses have been reported to be associated with both epidemics of acute diarrhoeal illness and with sporadic cases of gastroenteritis in children. In this study, we report the identification of genogroup II small round-structured viruses or human caliciviruses associated with an outbreak of winter vomiting disease in South Africa. The virus was initially identified by electron microscopic examination of the stools and then further characterised by recombinant immunoassay with expressed capsid proteins to human caliciviruses from genogroups I and II. Both antigenically by the EIA and by sequence analysis of a region of the RNA-dependent RNA polymerase gene, the virus was shown to belong to genogroup II of the human Caliciviridae.

Amino Acid Sequence↗
PubMed1996

Characterisation of rotaviruses recovered from neonates with symptomatic infection.

An unusually high number of diarrhoeal stools were obtained from neonates at different maternity units in Pretoria during late 1986 and the winter of 1987 and tested for the presence of rotavirus infection. Latex agglutination assay revealed rotavirus in 67% (93/139) of the stools from newborn babies. Gel electrophoresis of the rotavirus genome showed that a genomically stable strain of rotavirus was associated with the diarrhoeal illness in all maternity units investigated. Determination of the VP6 subgroup specificity using monoclonal antibodies demonstrated that all strains were of subgroup II. Examination of the VP4 and VP7 rotavirus genes, which encode for the outer capsid neutralisation proteins of the virus, was conducted by hybridisation analysis using probes directed at the divergent regions of the two genes. These results showed the presence of a VP7 serotype G4 rotavirus strain with a P6 VP4 genotype-the putative 'attenuated' VP4 gene allele-circulating in all maternity units studied.

Diarrhea, Infantile↗
PubMed1996

Group B and C porcine rotaviruses identified for the first time in South Africa.

The incidence of rotavirus at a pig farm in Gauteng was determined by polyacrylamide gel electrophoresis (PAGE). Faecal specimens were collected from 172 litters over a 6-month period. Rotavirus was detected in 37.8% of piglets exhibiting signs of scouring. When these PAGE patterns were examined, 84.6% group A, 4.6% group B and 10.8% group C rotaviruses were observed. A few specimens subsequently collected from other farms in the Gauteng. North-West and Northern Provinces also contained group B and C electropherotypes. This is the first report of group B and group C rotaviruses in the South African pig population.

Animals↗
PubMed1995

Relative frequency of human rotavirus VP4 (P) genotypes recovered over a ten-year period from South African children with diarrhea.

The relative frequency and distribution of the VP4 (P) genotypes of 227 human rotavirus field strains were investigated in South Africa. The stool samples were collected between 1984-1993 from infants and young children with diarrhea at Ga-Rankuwa Hospital, Pretoria, South Africa. The RNA was extracted from stools, heat denatured, and dot blotted onto nylon membranes. The blots were hybridized to PCR-generated, 32P radio-labelled VP4-specific probes (corresponding to the hyperdivergent region of the VP4 gene) of the following human rotavirus VP4 genotypes: P4, P6, P8, P9, P10, and P12. Of the 157 rotavirus strains typed by the probes, the P8 genotype was identified most frequently in 63.7% (n = 100) of the samples. The P4 and P6 genotypes were detected less frequently in 22.3% (n = 35) and 8.3% (n = 13) of the samples, respectively. Five cases of dual infection between P8 and P4 genotypes occurred, indicating the potential for reassortment between members of different rotavirus genogroups. The P9 genotype could not be confirmed in 3 cases (1.9%), while the P10 genotype was not observed at all, indicating the scarcity or absence of these VP4 genotypes in this region. Interestingly, we identified the newly-described P12 VP4 genotype in 6 cases (3.8%), suggesting a wide geographical distribution. Furthermore, several samples with sufficient RNA by gel electrophoresis remained untyped by the probes used in this study, and may represent putative "new" human VP4 genotype(s).

Base Sequence↗
PubMed1995

Repair of Descemet's membrane detachment after intraocular surgery.

We repaired three unselected cases of Descemet's membrane detachment. A visually successful outcome was achieved in one case, an anatomically successful outcome in another, and no improvement in the last. We believe that large detachments should be repaired early rather than waiting for possible spontaneous reattachment, and we advocate sulfur hexafluoride fluid-gas exchange as the procedure of choice.

Aged↗
PubMed1995

Topical anaesthesia for phacoemulsification surgery.

Although phacoemulsification with only topical anaesthesia is possible, the level of any discomfort perceived by the patient is unknown. Topical anaesthesia eliminates any risk of inadvertent ocular or orbital injury. Twenty-four patients undergoing phacoemulsification under only topical anaesthesia (g. amethocaine 1%) were compared with 23 patients undergoing the same procedure with peribulbar anaesthesia (5 ml lignocaine 2%, 5 ml bupivacaine 0.5% and 75 units hyaluronidase). Perceived pain on administration of the anaesthesia, per-operatively and post-operatively was assessed by a nursing officer using a visual analogue scale (0-10). It was found that there was no difference in pain score between the two groups on induction of anaesthesia. Per-operatively and post-operatively scores were higher in the topical group than in the peribulbar group (p < 0.05, Mann-Whitney U-test), though most of these were within the range 0-3, ('no pain' to 'slight pain'). There was no difference in the amount of analgesia dispensed to the two groups on the ward post-operatively. In conclusion, topical anaesthesia provides adequate anaesthesia for phacoemulsification. Although a small increase in the level of discomfort was observed, the pain levels reported were small and may not be clinically significant when set against the reduced incidence of anaesthetic-related complications.

Adult↗
PubMed1995

Detection and quantitation of hepatitis B virus DNA: comparison of two commercial hybridization assays with polymerase chain reaction.

Serum hepatitis B virus (HBV) DNA is now the most important and reliable marker for monitoring hepatitis B viral replication. Quantitative detection of HBV DNA in serum is based on commercial standardized molecular hybridization test systems. We compared two hybridization assays, the Digene Hybrid Capture assay (Digene Diagnostics, Beltsville, MD) and the Abbott HBV DNA assay (Abbott Laboratories, North Chicago, IL, USA) with the polymerase chain reaction (PCR) technique, for detection and quantitative measurement of serum HBV DNA. Forty-two patients with various HBV serological marker profiles were included in this study. The patients were divided into four groups according to their HBV DNA values after HBV DNA determination in the serum by the Abbott assay. For each patient HBV DNA was then determined by the Digene assay and by PCR. In the case of Digene and PCR there was a 97.6% correspondence in the outcome of the two methods, whereas in the Abbott assay and PCR there was only 69% correspondence. The McNemar test of symmetry showed no statistically significant difference between the Digene assay and PCR, whereas there was a significant difference (P < 0.01) in the Abbott assay and PCR. For low positive HBV DNA values between 1.5 and 20 pg ml-1 the Abbott assay yields inconclusive results. Differences observed between the two hybridization assays underline the need for standardization of HBV DNA quantitation.

DNA Probes↗
PubMed1995

Geographic distribution of human rotavirus VP4 genotypes and VP7 serotypes in five South African regions.

The rotavirus outer capsid proteins elicit the production of neutralizing antibodies and are known to play a role in inducing resistance to disease. In this study, cDNA probes directed at the six most common human rotavirus VP7 serotypes (G1 to G4, G8, and G9) and five human rotavirus VP4 genotypes (P4, P6, P8, P9, and P10) were utilized. Hybridization analysis of 572 human rotavirus strains collected from five regions in South Africa was performed to determine the distribution of the VP7 serotypes and VP4 genotypes in nature. VP7 serotype G1 was identified most frequently, occurring in 51% of the rotavirus strains tested. VP7 serotypes G2 and G4 occurred in similar numbers, although their distribution varied regionally. Few serotype G3 strains and no G8 or G9 strains were identified. The P8 VP4 genotype occurred most frequently overall (66%), and the P4 genotype was detected next most frequently. The P6 genotype was identified in 28 symptomatically infected neonates and in 8 symptomatic infants. Few P9 strains were identified. The potential for reassortment events was demonstrated by dual infections with different viruses.

Antigens, Viral↗
PubMed1995

Serologic markers for hepatitis B virus and hepatitis A virus in Bushmen in West Caprivi, Namibia.

A community based sero-epidemiological study was undertaken to determine the age specific prevalence rates of hepatitis A virus (HAV) and hepatitis B virus (HBV) infection in a band of Bushmen in the West Caprivi, Namibia. All children tested and all but two of the adults tested showed the presence of anti-HAV antibodies. Nineteen individuals (18%) were positive for HBsAg and 65 (61%) individuals had serologic evidence of past exposure to HBV infection.

Adult↗
PubMed1995

Sero-prevalence to hepatitis B and C virus infection in refugees from Mozambique in southern Africa.

Serological markers for evidence of past exposure to hepatitis B virus (HBV) and hepatitis C virus (HCV) were investigated in a cohort of refugees from Mozambique. Serological markers for past exposure to HBV were detected in 56% of the population and, in addition, 13.2% carried the HBV surface antigen. Anti-HCV antibodies could be confirmed in 3.2% of the population and occurred mostly in the older individuals. Only one anti-HCV antibody positive individual was positive for HBsAg. Immunity to rubellavirus had reached 85% by 11 years of age.

Adolescent↗
PubMed1995

Monitoring of rotavirus infection in a paediatric hospital by RNA electrophoresis.

During the spring of 1987 and the autumn of 1988, stool specimens were collected from infants and young children in the paediatric unit at H. F. Verwoerd Hospital, Pretoria, and examined for the presence of rotaviruses to assess the potential for hospital-acquired infection in the paediatric wards. Stool samples were also collected from children admitted to the hospital for causes unrelated to gastro-enteritis to investigate the possible asymptomatic carriage of rotavirus in this population. Hospital-acquired rotavirus infection was determined in only 9% of cases. Very little asymptomatic carriage of the virus was identified. Electrophoretic analysis of the rotavirus strains showed that the majority of the infections (20 of 42) were associated with a particular strain with a long RNA profile, while 7 minor strains co-circulated (5 with a long electrophoretype and 2 with a short one). An apparent small outbreak of nosocomial infection with a single strain was observed to occur in one of the paediatric wards during the spring and early summer.

Child, Preschool↗
PubMed1994

Identification of a new VP4 serotype of human rotaviruses.

A new VP4 gene allele was identified by sequencing of two rotavirus recovered from infants with diarrhea. Strains HAL1166 (a VP7 serotype 8 human rotavirus from Finland) and PA169 (a VP7 serotype 6 human rotavirus from Italy) present 22-43% nucleotide sequence divergence and 14-45% amino acid divergence in the VP4 gene with rotaviruses belonging to various VP4 gene alleles previously reported. Cross-neutralization analysis between PA169 and rotaviruses belonging to the other recognized VP4 (P) serotypes had previously shown that none of them was similar to PA169. Hyperimmune serum prepared against a reassortant with the VP4 gene of strain PA169 and the VP7 gene of serotype 2 strain DS1 failed to neutralize previously recognized human rotavirus VP4 serotypes, indicating that PA169 represents a new VP4 serotype specificity. In addition, one of four neutralizing monoclonal antibodies directed to the VP4 of PA169 was specific for this virus, while three others had very limited cross-reactivity with rotaviruses possessing different VP4s.

Amino Acid Sequence↗
PubMed1994

Granular corneal dystrophy. Visual results and pattern of recurrence after lamellar or penetrating keratoplasty.

BACKGROUND: Granular corneal dystrophy is a rare indication for corneal transplantation. Both penetrating and lamellar keratoplasty have been recommended, but because granular corneal dystrophy is known to recur within the donor material and multiple grafts may be necessary, the best surgical option has not been clearly established. The cellular cause of the dystrophy is unknown and the authors hypothesized that the rate and pattern of recurrence within lamellar and penetrating grafts might give clues to its etiology. METHODS: The authors compared the visual outcome, rate, and pattern of recurrence after 20 penetrating keratoplasties and 11 lamellar keratoplasties for granular corneal dystrophy. RESULTS: Penetrating keratoplasty and lamellar keratoplasty have a good visual outcome in granular corneal dystrophy. Visual acuities after both procedures were not statistically different. Recurrence of the dystrophy within the graft material was almost universal within 4 years. It first appeared centrally and superficially, occasionally adopting a vortex pattern suggesting epithelial involvement. The recurrence-free interval was independent of size and type of graft performed. CONCLUSION: The authors recommend lamellar keratoplasty as a primary procedure in managing visually disabling granular corneal dystrophy if the deposits are limited to the superficial cornea. This is particularly applicable in younger patients in whom multiple procedures may be necessary over a lifetime due to recurrence of the dystrophy, and the lower morbidity rate associated with lamellar keratoplasty becomes appreciable. Although granular corneal dystrophy generally is classified as a stromal dystrophy, the pattern of recurrence is more consistent with an epithelial or tear-borne abnormality than a disease of the stromal keratocyte.

Adolescent↗
PubMed1994

Postoperative blunt trauma to 7.5 mm scleral pocket wounds.

Two patients received blunt trauma to the operated eye after phacoemulsification cataract surgery. Both patients had a three-step 7.5 mm chord width, 3.0 mm long, curving incision, extending from sclera into clear cornea. One patient had rupture of the scleral tunnel and horizontal suture 20 days after surgery. The intraocular lens was dislocated into and along the scleral tunnel. The second patient had direct trauma four days after surgery, resulting in cheese-wiring of the horizontal nylon 10-0 suture and wound leakage but no other sequelae. Blunt trauma after scleral pocket phacoemulsification cataract surgery may result in clinical wound dehiscence if sufficient force is sustained.

Cataract Extraction↗
PubMed1994

Prevalence of hepatitis B in !Kung (San) children from Bushmanland, Namibia.

Serum samples from 248 predominantly !Kung children (aged 5-19 years) attending various bush schools and a clinic in Bushmanland, northern Namibia were examined for the presence of hepatitis B virus (HBV) markers by radioimmunoassay. HBsAg was detected in 18 (7.3%) children while 117 (47.6%) showed one or more markers of HBV infection. These prevalence rates are lower than those of the closely situated territory of Kavango to the north and East Caprivi to the north-east. No significant difference in HBs antigenaemia between !Kung boys and girls was found (p > 0.05). However, HBs antigenaemia was found to vary between children in different bush schools. A significantly higher number of children attending the Omatako bush school were positive for HBsAg than the number attending the Luhebu bush school (p < 0.0167). These local variations could assist in the initial targeting of HBV vaccine to high-risk areas. In situ investigations of hyperendemic foci in Bushmanland, Namibia should help to elucidate the variation in HBs antigenaemia and the factors responsible for transmission of HBV.

Adolescent↗