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S Knowles

Publications and source records attributed to S Knowles.

At least 37 records · Page 2Linked to original sources
PubMed1997

An explanation and the clinical significance of the failure of microcolumn tests to detect weak ABO and other antibodies.

Shear forces are proposed to explain the failure of antiglobulin and 'neutral' (no antiglobulin) microcolumn tests at 37 degrees C to detect weak ABO incompatibilities and other weak antibodies, clearly detectable by spin-tube methods. These shear forces can be minimized in a microcolumn test using a biphasic centrifugation phase. Although this biphasic test is not suitable for routine use, it may be of use as an investigational method for reference laboratories. This failure of microcolumn test to detect weak ABO incompatibilities is of little clinical significance as the antibodies are dubiously active at 37 degrees C.

ABO Blood-Group System↗
PubMed1997

Serious dermatologic reactions in children.

Although serious reactions comprise only a small percentage of total adverse drug reactions, they are important in terms of morbidity and potential mortality. An update on serious dermatologic reactions in children is presented including serum sickness-like reactions due to cefaclor, hypersensitivity syndrome reactions (HSRs), and drug-induced pseudoporphyria. More detailed information on minocycline-induced reactions including drug-induced lupus and HSRs and lamotrigine-induced toxic epidermal necrolysis and Stevens-Johnson syndrome will be discussed.

Adverse Drug Reaction Reporting Systems↗
PubMed1997

Changes in folate supplementation, and in serum and red cell folate levels in antenatal patients over the course of a health promotion project for the prevention of neural tube defects.

We assessed the use of folic acid supplements and changes in serum and red cell folate levels in pregnancy over the course of a health promotion project in Western Australia by 4 cross-sectional studies of women attending a public antenatal outpatient clinic in 1992 (before the launch of the health promotion project), 1993, 1994, and 1995. A short questionnaire was completed and blood taken for estimation of serum and red cell folate. There was an increase in the proportion of women taking folic acid supplements in the first trimester (51.9% in the final phase) and before pregnancy (15% in the final phase of the study), and no change in the proportion taking other vitamin supplements. Serum and red cell folate levels increased significantly over the study period in both women taking and not taking folic acid supplements. The proportion of women who had seen the pamphlet used in the health promotion project rose to 35.4% in the third phase, and fell to 27.8% in the final phase. Coincident with the health promotion project, there was an increase in folate status in early pregnancy. However, most women were not taking folic acid supplements before they became pregnant and, hence may not have had sufficient folate at the time of normal neural tube closure.

Erythrocytes↗
PubMed1996

Concordance between p53 protein overexpression and gene mutation in a large series of common human carcinomas.

Immunohistochemical (IHC) detection of p53 protein was compared with the presence of p53 gene mutation in many colorectal (n = 100), breast (n = 92), endometrial (n = 122), and gastric (n = 116) carcinomas. Two commercially available antibodies, DO7 and CM1, were used for IHC analysis of paraffin-embedded tissue sections. Screening for gene mutations in frozen and paraffin-embedded tumor samples was carried out using polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP). The frequency of nuclear staining with DO7 or CM1 for each tumor type, respectively, was colorectal (36%, 23%); breast (15%, 19%); endometrial (21%, 33%); and gastric (23%,-). Overall correlation between the two antibodies for nuclear staining was 90% for the 314 tumors analyzed. Cytoplasmic staining was observed with DO7 in 7% of breast and 5% of gastric carcinomas and with CM1 in 17% of breast and 54% of endometrial carcinomas. p53 gene mutation was found in 39% of colorectal, 28% of breast, 13% of endometrial, and 25% of gastric cancers. The concordance between p53 nuclear overexpression and gene mutation (both positive or both negative) was 68% for colorectal, 79% for breast, 76% for endometrial, and 73% for gastric carcinomas. This study provides further evidence that IHC detection of p53 protein accumulation does not always indicate the presence of a gene mutation and vice versa. Discordant results were observed in approximately 20% to 30% of the tumors studied, highlighting the need for careful characterization of both p53 gene and protein alterations when assessing the relationship between p53 status and tumor behavior.

Breast Neoplasms↗
PubMed1996

Overexpression of p53 protein is an independent prognostic indicator in human endometrial carcinoma.

The important role of the p53 gene in tumour progression and cellular response to DNA damage has prompted investigation of the clinical significance of alterations to this gene. We examined both p53 overexpression and mutation of the gene in endometrial carcinoma in order to evaluate the prognostic significance of these changes. Of 122 endometrial carcinomas, 33 (27%) showed overexpression of p53 in the nucleus and 66 (54%) in the cytoplasm. Mutation in the p53 gene was found in 16 (13%) cases but showed no significant association with patient survival. Nuclear p53 overexpression was associated with poor survival (48% vs 80% alive in negative tumours 5 years post operatively, P < 0.001). In contrast, cytoplasmic p53 overexpression was associated with better survival (85% vs 55%, P < 0.001). When patients were separated into prognostic subgroups according to established clinical markers, these associations remained significant within most subgroups examined. In multivariate analysis adjusted for surgical stage, histological grade and type and vascular invasion, both nuclear p53 overexpression [hazard ratio 4.9 (95% CI 1.3-17.6). P = 0.016] and cytoplasmic overexpression [0.25 (0.06-0.98), P = 0.047] were independent prognostic factors. Immunohistochemical assessment of p53 overexpression in the nucleus and cytoplasm could provide useful prognostic information for the management of patients with endometrial cancer.

Biomarkers, Tumor↗
PubMed1995

Observer reliability in assessing placental maturity by histology.

AIMS: To evaluate the ability of five experienced perinatal pathologists to assess placental maturity reliably by histology. METHODS: Twenty four haematoxylin and eosin slides, six each from placentas of 27, 31, 35, and 39 weeks' gestation, were circulated to five pathologists on three separate occasions. The slides were labelled with the correct or incorrect gestational ages. RESULTS: The mean absolute error over all 360 readings was 2.72 weeks. Only 54% of the slides were assessed within two weeks of the correct gestation. Pathologist tended to overestimate younger gestations and underestimate older gestations. Two, and possibly three, pathologist were influenced by the gestational age state on the label. One pathologist, who did not appear to be influenced by the label, was more accurate in diagnosing gestation of the placentas than other colleagues. CONCLUSIONS: Experienced pathologists can have difficulty in assessing the villous maturity of placentas by histology. They can also be influenced by clinical information provided, such as gestational age. Other observer reliability studies must address the issue of the influence of labelled information on observer variation. A difference in maturation would have to be of a six week magnitude to have a chance of being detected by current methods. This may limit the value of the histological diagnosis of placental dysmaturity as a surrogate marker for uteroplacental ischaemia.

Analysis of Variance↗
PubMed1994

Multiple marker screen positivity in the presence of hydrops fetalis.

Three cases of hydrops fetalis presented in the second trimester as screen-positive for Down syndrome using multiple maternal serum markers. One case was a karyotypically normal female; one case was a monosomy X (Turner syndrome); and one case was a trisomy 21 (Down syndrome). In each case, the maternal serum human chorionic gonadotrophin (hCG) was disproportionately elevated. These cases support the contention that hydrops fetalis of any aetiology may present as screen-positive when using multiple maternal serum markers for Down syndrome. Further cases will be necessary before it can be determined whether a disproportionately elevated hCG is predictive of hydrops.

Adult↗
PubMed1994

Metronidazole hypersensitivity.

OBJECTIVE: To report a case of a possible hypersensitivity reaction induced by metronidazole. CASE SUMMARY: An Asian woman with a history of recurrent vaginitis had previously developed localized erythema while on intravaginal metronidazole and nystatin. While receiving oral metronidazole for treatment of a current bacterial vaginosis, she developed chills, fever, generalized erythema, and a rash within 60 minutes of the first dose. Treatment with diphenhydramine was instituted. The following day while in the hospital, the patient's condition worsened; she experienced shortness of breath and increased edema of the extremities. Methylprednisolone was administered with diphenhydramine and her condition improved over the next 5 days. The patient's vaginitis was treated with gentian violet and she was discharged on a tapering dosage of prednisone. DISCUSSION: Metronidazole-induced cutaneous reactions and systemic hypersensitivity reactions are reviewed. Alternatives to metronidazole and other potential cross-reactive drugs are suggested for the treatment of recurrent vaginitis. CONCLUSIONS: Although the patient's initial reaction to metronidazole represented a rare event, written documentation and communication in the patient's native language may have prevented the subsequent severe hypersensitivity reaction.

Adult↗
PubMed1993

Anthropometric measurements in the second trimester fetus.

Normal anthropometric measurements, of accepted value for clinicians and pathologists in the assessment of the dysmorphic neonate, have not in the past been available for the second trimester fetus, in which dysmorphic features are often more subtle and objective measurements most needed. In order to establish these values 19 anthropometric measurements, comparable to those published for the larger fetus and neonate, were recorded at autopsy on each of 260 overtly normal non-macerate singleton fetuses between 13 and 26 weeks gestation. Regression lines for each parameter, and growth ratios of potential value for description and assessment of dysmorphic features, were derived. The sex ratio was 1.27 and as there was no statistically significant sex difference for any of the 19 measurements chosen, the data was subsequently pooled. There were linear correlations between gestational age and each growth parameter, all but three exceeding 0.90. The linear correlations between pairs of growth parameter were higher than the correlations between gestational age and individual growth parameters. This suggests that growth parameter pairs, expressed as a ratio, are less affected by errors in gestational age estimation. Ratios enabling the dysmorphologist to more objectively assess common observations such as abnormalities of head shape, relationship between limb and trunk length and gross proportional relationships between major body segments were derived. Collected measurements were compared with established ultrasound reference ranges. While reference ranges for biparietal diameter and head circumference showed close concordance with those derived from ultrasound measurements, the abdominal circumference was consistently lower than that measured by ultrasound possibly because of differing trunk positions in utero compared with after death. The graphs and ratios derived in this study can be rapidly applied to confirm visual impressions at clinical examination and at autopsy.

Anthropometry↗
PubMed1993

Amniotic band syndrome: a population-based study in two Australian states.

A search for cases of amniotic band syndrome was made in two population-based Australian birth defects registries, using defined selection criteria. Over a period of 4 years in Western Australia and 5 years in South Australia, 25 cases of amniotic band syndrome had been identified as such by the two registries, and an additional 15 new cases were identified by the study selection process, giving an annual prevalence of amniotic band syndrome over the study period of 2.03 per 10,000 births. Similar proportions of male and female infants were affected, although the syndrome was more common in mothers younger than 25 years of age, and in first births. Limb defects only (upper and/or lower) were found in 24 cases, limb-body-wall defects in four cases, and complex craniofacial and other malformations in 12 cases. A heightened awareness of the syndrome should enhance the identification of amniotic band syndrome, which has implications for genetic counselling, and our understanding of the aetiology and pathogenesis of this condition.

Amniotic Band Syndrome↗
PubMed1993

A fatal case of necrotizing enterocolitis in a neonate with polyagglutination of red blood cells.

An infant of 30 weeks gestation developed necrotizing enterocolitis (NEC) 8 days after birth and died 2 days later after a fulminating course. During her illness she received two blood transfusions, both of which produced sub-optimal rises in her haemoglobin and were associated with evidence of haemolysis. Retrospective analysis demonstrated T antigen (Tk) polyagglutination of the infant's red blood cells and donor plasma. Although bacterial cultures were negative throughout the course of the illness in this case, T antigen exposure is associated with certain anaerobic infections and with severity of NEC. Infants with NEC should be regularly screened for T antigen exposure and if this test is positive, plasma (immunoglobulin) containing infusions should be avoided.

Blood Component Transfusion↗
PubMed1993

Cryopreservation of red blood cells: effect of freezing on red cell quality and residual lymphocyte immunogenicity.

AIMS: To investigate treatment with glycerol/washing as a potential substitute for freeze-thawing in the production of leucocyte depleted red cell concentrates for patients with a history of non-haemolytic reactions following transfusion. METHODS: The standard procedure of treatment with glycerol/-80 degrees C freezing/thawing/washing was compared with a similar procedure in which freezing was omitted. The quality of the resulting red cell products was assessed in relation to: (1) standard red cell biochemical parameters; (2) leucocyte and lymphocyte subset composition using flow cytometry with fluorescent labelled monoclonal antibodies; and (3) immunogenicity of the residual lymphocytes in mixed lymphocyte culture. RESULTS: Compared with red cells subjected to the standard freeze-thaw technique, red cells undergoing the non-freezing procedure and suspended in additive solutions had significantly better biochemical preservation after 21 days of storage (p < 0.001). Both procedures removed an average 98% of the initial leucocytes at the expense of 18-20% of the red cells. The non-freezing procedure resulted in higher residual concentrations of HLA class II bearing lymphocytes (p < 0.01), but not higher numbers of dendritic cells. Both procedures were equally effective in annulling the residual lymphocytes' ability to act as stimulator cells in one-way mixed lymphocyte culture. CONCLUSIONS: The non-freezing procedure produces a superior product for the provision of red cells to patients with granulocyte antibodies. These products may also offer a lower risk of HLA alloimmunisation to previously unexposed patients.

Blood Preservation↗