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Biomedical subjects

M Silink

Publications and source records attributed to M Silink.

At least 73 records · Page 4Linked to original sources
PubMed1987

Determination of 17-oxosteroid glucuronides and sulphates in urine by liquid chromatography using 2,4-dinitrophenylhydrazine as a prelabelling reagent for spectrophotometric detection.

A direct, convenient method using high-performance liquid chromatography with spectrophotometric detection has been developed for the determination of conjugated 17-oxosteroids in urine without hydrolysis. Conjugated 17-oxosteroids are extracted with a Sep-Pak C18 cartridge, prelabelled with 2,4-dinitrophenylhydrazine in trichloroacetic acid-benzene solution and then separated by high-performance liquid chromatography on a reversed-phase C18 column using a mobile phase of 70% methanol in a buffer consisting of 50 mM sodium acetate in 2% (v/v) acetic acid. The eluate is monitored by a spectrophotometer at 380 nm and a linear response was found for absorbance readings (peak heights) from amounts of various conjugated oxosteroids between 25 and 250 ng. The method provides a sensitive, reliable technique for the analysis of urinary 17-oxosteroid conjugates.

17-Ketosteroids↗
PubMed1987

Growth failure and growth-hormone deficiency after treatment for acute lymphoblastic leukaemia.

In a study of 77 children who had been treated for acute lymphoblastic leukaemia (ALL) with an LSA2L2 (Memorial Sloan-Kettering) chemotherapy protocol plus radiotherapy (24 Gy) as cranial prophylaxis, growth was examined 3.0-9.5 years after diagnosis. The children's growth slowed and they crossed height percentiles towards the end of or after treatment. The Z-score, which reflects the deviation of height measurements from the population mean, was used to assess height change. The mean Z-score was 0.16 at diagnosis, -0.30 2 years later, -0.71 4 years later, and -1.37 6 years later. Height for age had fallen by more than 1 standard deviation of the population mean in 32% of survivors 4 years after diagnosis and in 71% 6 years after diagnosis. Younger children and those tall for age at diagnosis were more severely affected. Growth-hormone (GH) response to standard provocation tests was measured in 46 patients; 30 had partial or complete GH deficiency. Mean pulsatile GH secretion was low in the 34 patients tested. Cranial irradiation is probably the most important causative factor in the development of GH deficiency in survivors of ALL.

Adolescent↗
PubMed1987

Adrenocortical responsiveness in neonates weaned from the ventilator with dexamethasone.

Adrenocortical responsiveness was assessed in eight very low birthweight neonates who had bronchopulmonary dysplasia and had been weaned from mechanical ventilation using dexamethasone. Three of the eight infants did not respond to ACTH stimulation during the first week after cessation of dexamethasone, but all three responded normally when retested at least 1 month later. The present authors have thus demonstrated that some infants have at least temporary adrenocortical unresponsiveness after prolonged courses of glucocorticoid therapy, and suggest that adrenocortical function should be assessed in all infants who are weaned from mechanical ventilation using dexamethasone.

Adrenal Cortex↗
PubMed1986

First morning urinary albumin concentration is a good predictor of 24-hour urinary albumin excretion in children with type 1 (insulin-dependent) diabetes.

Twenty-four hour urinary albumin excretion was measured in 97 children with Type 1 (insulin-dependent) diabetes and found to have a geometric mean of 6 mg/day (range 1-38 mg/d). The same geometric mean of 6 mg/day (range 1-45 mg/d) was found in 120 normal children. The relationship of 24-h urinary albumin excretion to the albumin concentration (mg/l) and to the ratio of albumin: creatinine (mg:mmol) on first morning urine samples in 64 patients was highly significant (r = 0.93 and r = 0.62 respectively, p less than 0.001). In 41 patients, the relationship between 24-h urinary albumin excretion and albumin concentration upon urine samples at various times was assessed. The correlation was highest on the first morning sample (r = 0.86); 09.00 h to 13.00 h, 0.51; 13.00 h to 18.00 h, 0.68; 18.00 h to 23.00 h, 0.32. High sensitivity and moderate specificity was obtained using a first morning albumin concentration of greater than 20 mg/l to detect increased albumin excretion. These results show that the measurement of albumin concentration on the first morning urine sample can be used for a screening test for microalbuminuria in children.

Adolescent↗
PubMed1985

Coxsackie B, mumps, rubella, and cytomegalovirus specific IgM responses in patients with juvenile-onset insulin-dependent diabetes mellitus in Britain, Austria, and Australia.

Patients from England, Austria, and Australia with recently diagnosed juvenile-onset insulin-dependent diabetes (type 1) mellitus (IDDM) and matched controls were tested for specific IgM responses to Coxsackie B1-5 viruses. 37 of 122 (30%) patients aged less than 15, but only 15 of 204 (6%) controls, were positive (p less than 0.005). Differences in Coxsackie B virus specific IgM responses between patients and controls were statistically significant for patients in England and Austria (p less than 0.005). Coxsackie B virus specific IgM responses were detected in only 3 of 31 patients aged greater than 16. Virus-specific IgM responses were directed against a single serotype, usually Coxsackie B4 or 5, in 23 of 37 (62.5%) children aged less than 15; 10 of 13 (77%) of children aged less than 7 had monotypic responses. Among families of Austrian patients with IDDM, 8 of 79 (10%) siblings had Coxsackie B virus specific IgM responses, 1 of whom subsequently had IDDM, but none of the 80 parents was positive. In contrast, there was no evidence of recent infection by mumps, rubella, or cytomegalovirus (CMV), since mumps-virus specific IgM was present in only 2 of 100 children with IDDM and 5 of 139 controls; no rubella or CMV specific IgM responses were detected in 60 sera from patients with IDDM.

Adolescent↗
PubMed1985

Residual insulin secretion in insulin dependent diabetes mellitus.

The residual insulin secretory capacity of 244 children with insulin dependent diabetes mellitus was determined by measurement of their 24 hour urinary C peptide excretion. An inverse linear relation was found between the residual B cell secretion and the duration of diabetes. The age at onset of diabetes did not affect the residual B cell function significantly.

Adolescent↗
PubMed1984

Colorimetric measurement of glycosylated protein in whole blood, red blood cells, plasma and dried blood.

A colorimetric method for the measurement of whole-blood glycosylation (WBG), glycosylated haemoglobin in red blood cells (GHb), glycosylated plasma protein (GPP) and dried-blood glycosylation (DBG) is described which is rapid, inexpensive and precise. GHb correlated well with HbA1 measured by cation-exchange chromatography and was also correlated with WBG, DBG and GPP. DBG, which showed good correlation with GHb, could be measured on several drops of blood dried on filter paper treated with glucose oxidase. Filter papers are posted to the laboratory prior to clinic visits, and by having the DBG result available more rational diabetic management is possible. For DBG, the intra- and inter-assay coefficient of variation at three levels is less than 6%. Reference values in non-diabetic children have been calculated and are compared with values obtained in 'good' clinical diabetic control and in 'fair' control. The filter-paper assay DBG method has a high degree of patient acceptance.

Blood Glucose↗
PubMed1982

Celite multi-column chromatography for the simultaneous separation of progesterone, deoxycorticosterone and 17 alpha-hydroxyprogesterone from small plasma or tissue samples.

A rapid, inexpensive and reliable chromatographic method has been developed for the simultaneous separation of progesterone, deoxycorticosterone and 17 alpha-hydroxyprogesterone on 15-cm Celite columns using n-heptane-benzene-methanol-water (100:35:80:20) as mobile phase. Six columns can be run in parallel within an hour with the assistance of nitrogen pressure. There is negligible column-to-column or batch-to-batch variation with consistent high recoveries. Columns are easily and quickly prepared and being inexpensive are disposable which is important when working with radioactivity. Using this method three important corticosteroids can be rapidly and reliably isolated from 20-30 small plasma or tissue samples per day.

Adrenal Glands↗
PubMed1981

Cerebrospinal fluid lactic acidosis in bacterial meningitis.

A rapid, microenzymatic method was used to measure cerebrospinal fluid lactate levels in 205 children with suspected bacterial meningitis. Fifty children with normal CSF containing fewer than 0.005 X 10(9)/l WBC, no segmented neutrophils, glucose 3.4 +/- 0.8 mmol/l (61.2 +/- 14.4 mg/100 ml), and a protein of less than 0.30 g/l had CSF lactate levels below 2.0 mmol/l (18 mg/100 ml) (mean and standard deviation 1.3 +/- 0.3 mmol/l (11.8 +/- 2.7 mg/100 ml)). In 31 cases of proved viral meningitis as with 58 cases of clinically diagnosed viral meningitis, levels were below 3.8 mmol/l (34.5 mg/100 ml), being 2.3 +/- 0.6 mmol/l (20.9 +/- 5.4 mg/100 ml), and 2.1 +/- 0.7 mmol/l (19.1 +/- 6.4 mg/100 ml) respectively. Sixty-six cases of bacterial meningitis had CSF lactate levels ranging from 3.9 mmol/l (35.4 mg/100 ml) to greater than 10.0 mmol/l (90.0 mg/100 ml). Longitudinal studies in 7 children with bacterial meningitis showed that cerebrospinal fluid lactate levels differentiated bacterial from viral meningitis up to 4 days after starting treatment with antibiotics. Use of CSF lactate measurement for monitoring the efficacy of treatment is illustrated in a case of bacterial meningitis due to Pseudomonas aeruginosa. The origin of the cerebrospinal fluid lactate acidosis and the role of lactate in the pathophysiological cycle leading to intensification of brain tissue hypoxia and cellular damage is discussed with respect to the short-term prognosis and the long-term neurological sequelae.

Acidosis↗
PubMed1981

Bilateral optic nerve hypoplasia.

In the past 10 years, 15 children with bilateral optic nerve hypoplasia have been studied at the Royal Alexandra Hospital for Children. There were 5 boys and 10 girls. Nine were first-born and they presented at a mean age of 5 months (range: 4 days to 25 months). Five presented with suspected blindness and 7 with abnormal eye movements (nystagmus or less commonly squint). The other 3 presented because of fits or developmental delay. Eight showed evidence of neural damage--microcephaly, seizures and/or abnormalities of tone. Four appeared to be of normal or near normal intelligence, 6 were mildly retarded and 5 severely so. Two patients had already died, one suddenly. Six of the 7 cases investigated in detail had evidence of hypothalamic pituitary dysfunction. Another one had a minimal hypothalamic abnormality. Four were severely growth retarded and 2 were receiving growth hormone replacement. Two males had micropenis and a girl had precocious puberty with partial diabetes insipidus. Neuroradiological investigations showed an absent septum pellucidum in only 5 cases. Five patients had other major CNS malformations. Five patients had normal CT scans; 3 of these 5 appeared of normal intelligence and all 5 had normal neurological examinations. Bilateral optic nerve hypoplasia is frequently associated with serious brain and endocrine abnormalities.

Brain↗