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Biomedical subjects

I S Ross

Publications and source records attributed to I S Ross.

At least 37 records · Page 2Linked to original sources
PubMed1988

The influence of maternal glucose metabolism on fetal growth, development and morbidity in 917 singleton pregnancies in nondiabetic women.

To study the effects on the fetus of variations in maternal glucose tolerance, a 25 g rapid intravenous glucose tolerance test was performed at or about 32 weeks gestation in 917 randomly selected nondiabetic women with singleton pregnancies. The results were withheld from the patients and their obstetricians and paediatricians, and no treatment or advice was offered. Fasting plasma glucose and indices of glucose disposal (including a new index which we have termed "summed glucose") were distributed unimodally, with no evidence of a separate pathological group towards the diabetic end of the distributions. Significant associations were found between maternal glucose metabolism and various measures of neonatal nutrition and morbidity, including the incidence of congenital malformations and morbidity related to asphyxia, suggesting that variations within the normal range in maternal glucose metabolism can influence growth and development in the fetus. These relationships were continuous throughout the range of maternal glucose tolerance and were not of predictive value in individual cases.

Birth Weight↗
PubMed1988

Increased nerve polyol levels in experimental diabetes and their reversal by Sorbinil.

Sciatic nerve glucose, sorbitol, fructose and myo-inositol levels were measured over a 24-week period in rats made diabetic using a single intraperitoneal injection of streptozotocin at 45 mg kg-1 body weight. In addition, the effect of the aldose reductase inhibitor Sorbinil (Pfizer Ltd) at 25 mg kg-1 day-1 in reversing the accumulation of nerve polyols following 8 weeks of diabetes was investigated. Following induction of diabetes 47, 471 and 456% increases and a 43% decrease in sciatic nerve glucose, sorbitol, fructose and myo-inositol concentrations (mumol g-1 wet weight) respectively, were observed by day 14. Over the remainder of the experimental course untreated diabetic control animals demonstrated relatively consistent elevations in sciatic nerve glucose, sorbitol and fructose. Although a significant, progressive reduction in sciatic nerve myo-inositol to 30% of onset values was observed over the first 84 days of the study, this was followed by a spontaneous partial recovery (31%) over the remainder of the experimental course. However, sciatic nerve myo-inositol levels at the end of the study were still significantly lower than onset values (P less than 0.01). Sorbinil treatment, initiated after 8 weeks of diabetes, and without effect on sciatic nerve glucose levels, normalized sorbitol concentrations following 4, 8, or 12 weeks of treatment but only partially reversed the accumulation of fructose by 368, 161 and 199%, compared to age-matched non-diabetic control values, at the above times, respectively. Mean myo-inositol levels were progressively increased following Sorbinil treatment over the experimental period, although the increase was only significant, compared to results from untreated diabetic animals, at weeks 4 and 16.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldehyde Reductase↗
PubMed1986

Glycated haemoglobin and glycated plasma protein, a comparative study.

Three different analytes reflecting the degree of glycation of different proteins have been used in order to determine which showed best correlation with the glycaemic control of different groups of diabetic patients. 1, Glycated haemoglobin by a semi-automatic colorimetric technique was able to discriminate between the best and worst controlled of the selected diabetic groups; 2, a semi-automated colorimetric glycated plasma protein assay was unable to distinguish between any of the diabetic groups in the study; 3, a dye reducing estimation of glycated plasma protein (Fructosamine) was best able to distinguish between the groups in the study.

Adolescent↗
PubMed1986

The effects of sorbinil on peripheral nerve conduction velocity, polyol concentrations and morphology in the streptozotocin-diabetic rat.

This study examined the effects of an aldose reductase inhibitor, Sorbinil, on neuropathy over a 6-month period in streptozotocin-diabetic rats. Sorbinil treatment prevented the 10-fold increase in nerve sorbitol found with diabetes. It produced a 60% improvement in tibial nerve motor conduction velocity after 6 months. Morphometric profiles of nerves were also normalized. Axon area was reduced by 14% in untreated diabetic rats compared to age-matched controls, whereas Sorbinil-treated animals showed normal age-related axon growth. Myelin area was increased by 28% in untreated diabetic animals, but was the same as age-matched controls with Sorbinil treatment. Nerve myo-inositol levels were reduced by 45% after three months of untreated diabetes, but were normal after six months. Sorbinil treatment tended to restore myo-inositol levels toward normal over the shorter time period. It was concluded that axon growth retardation is the most likely cause of the conduction deficit seen in long-term experimental diabetes.

Age Factors↗
PubMed1985

Functional characteristics of the glomerular filter in the IgA-nephropathy.

The purpose of the present study was to compare the functional characteristics of the glomerular filter in patients having a well defined glomerulonephritis, the IgA nephropathy, with those of normal age-matched controls. A bolus intravenous injection of inulin (60 mg/kg), para-amino hippuric acid (36 mg/kg) and Rheomacrodex (130 mg/kg) was administered to each subject and followed by the timed collection of venous blood and urine samples. Compared to the controls, the nine patients with IgA nephropathy had no significant differences in renal plasma flow or glomerular filtration rate. The control group showed filtration of the neutral graded dextrans which diminished in a linear fashion with increasing molecular size. In contrast, the IgA patients showed two-phased glomerular sieving with a reduction in the filtration of dextrans sized 40 A or less and an increased filtration of those larger than 50 A. These changes in dextran filtration indicate the appearance of a population of larger than normal pores in the glomerular filter in the IgA nephropathy, although concomitant alterations in the electrostatic properties of the filter mechanism cannot be excluded.

Adolescent↗
PubMed1983

A collaborative study of the measurement of glycosylated haemoglobin by several methods in seven laboratories in the United Kingdom.

A collaborative study compared methods for measuring glycosylated haemoglobin in seven laboratories in the United Kingdom. No satisfactory standard for general use was found. Satisfactory internal quality control systems were in use for each assay which allowed the maintenance of a normal range in each participating laboratory. No satisfactory quality control system suitable for general use could be identified. Costs and convenience of the assays are reported. The technical problems with each type of assay and precautions for their use were identified, such as the need for standardization in incubation times, the practicability of automation of colorimetric assays, and the precision of pH needed for buffers in column separation methods. The relevance of the technical problems to interpretation of measurements is also considered. It is concluded that laboratories measuring glycosylated haemoglobin should maintain a normal range, use 'in-house' quality controls to monitor assay performance and keep clinical colleagues informed of the findings and of any changes in methodology that might affect the interpretation of results.

Autoanalysis↗
PubMed1983

Thyroid hormones in the sudden infant death syndrome (SIDS).

Results are presented of serum total T4, T3, and TSH measurements on 92 patients. There are 34 infants exhibiting the sudden infant death syndrome, 36 in control group 1, who are matched both for age of infant and for duration of storage of specimen, and 22 post-mortem sera from non-SIDS deaths. There is no significant difference between the groups for total T4 measurements, but there is a highly significant elevation of both total serum T3 and TSH in the SIDS group compared with control group 1. It is suggested that the TSH elevation may be due to a post-mortem effect, but the T3 results appear to confirm and extend the recent publication of Chacon et al [1]. Evidence of one case of a near-SID that subsequently died is presented, demonstrating that disturbances of thyroid function tests occurred in this patient before death.

Humans↗
PubMed1983

N-Acetyl-beta-D-glucosaminidase levels and the onset of diabetic microangiopathy.

N-Acetyl-beta-D-glucosaminidase (NAG) levels in serum and urine from diabetics have been measured over a three-year period to assess their potential as indicators of the onset of retinopathy and nephropathy. The presence of retinopathy and nephropathy was confirmed by fluorescein angiography performed at the end of the study and by proteinuria, respectively. Three groups of diabetics were investigated, those on insulin, on oral hypoglycaemics, or on diet only. There was no apparent correlation between total NAG activity in serum with the development of retinopathy, nor were serum isoenzyme variations useful in this context. However, urine total NAG activity demonstrated a striking difference between diabetics of all groups and normals. In particular the B isoenzyme doubled in diabetics. The potential use of this finding in relation to prediction of the onset of microangiopathy is discussed.

Acetylglucosaminidase↗
PubMed1982

Diabetes produced in mice by smoked/cured mutton.

There is circumstantial evidence of a causal connection between type 1 diabetes in young Icelandic males and consumption of smoked cured mutton, containing N-nitroso compounds, by their parents at about the time of conception. This hypothesis has been examined in CD1 mice, and such processed mutton, consumed by the parents before mating and during pregnancy and by the offspring from day 19 until study 1-5 weeks later, produced diabetes in just over 16% of male progeny and 4.2% of female progeny. Light and electron-microscopic changes in the beta-cells were those of stages of cell death. The parent mice showed no features of diabetes. When both parents were fed the Icelandic cured mutton only up to the time of fertilisation, there was first a fall and then a significant rise in the plasma glucose of the male progeny after the 3rd week of age. The female progeny showed a significant fall in plasma glucose at 5-6 weeks of age. These findings suggest that an environmental factor in the aetiology of human diabetes mellitus had been identified. The mechanism seems to involve parental as well as maternal influences of germ cells.

Animals↗
PubMed1982

Fat as an energy supplement for preterm infants.

The absorption and utilisation of dietary fat as an energy supplement was studied in 15 healthy preterm infants. They were given two formulae for periods of one week. The standard low solute feed supplied 6 g fat and 476 kJ (114 cal) per kg. The high energy feed supplied 10 g of the same fat and 623 kJ (149 cal) per kg. Fat supplementation resulted in increased absorption (significantly higher chylomicron levels) without steatorrhoea or metabolic disturbance, apparently unchanged differential absorption of fatty acids, and a significantly higher rate of weight gain (mean 25.9 +/- 4.6 compared with 20.3 +/- 4.4 g/24 h). A high energy formula prepared with supplements of complex dietary fat is therefore of potential value in ensuring the adequate nutrition and growth of preterm infants.

Animals↗
PubMed1979

A semi-automated method for the determination of glycosylated haemoglobin.

A new routine, automated method for the determination of glycosylated haemoglobin is presented. The method offers improvements in analytical capacity, and precision, together with reduced running costs over existing methods, which should assist in making the determination of glycosylated haemoglobin more readily available to the clinician treating diabetes.

Autoanalysis↗
PubMed1979

N-Acetyl-beta-D-glucosaminidase levels and diabetic microangiopathy.

N-Acetyl-beta-D-glucosaminidase (NAG) activity has been measured in the serum and urine of primary and secondary diabetics and in primary diabetics with microangiopathy. NAG activity has also been measured in the tears of diabetics with ocular complications and diabetics with no ocular changes. Results have shown significantly higher levels of urinary NAG in diabetics with proteinuria (p less than 0.001) and proteinuria and retinopathy (p less than 0.001). There was no correlation between urinary NAG activity and serum creatinine (r = 0.28) or urinary NAG and the degree of proteinuria (r = 0.24). Increased urinary NAG levels were also observed in secondary diabetes associated with haemochromatosis and acromegaly. Significantly higher serum NAG levels were found in newly diagnosed diabetics (p less than 0.01) and significantly lower levels in chemical diabetics (p less than 0.01). Compared to non-diabetic controls tear NAG levels were significantly higher in the diabetic controls (p less than 0.01), in diabetics with retinopathy (p less than 0.01), and in diabetics with cataract formation (p less than 0.05). An assessment of this enzyme is made in relation to the development of diabetic microangiopathy.

Acetylglucosaminidase↗
PubMed1979

Serum and urine N-acetyl-beta-D-glucosaminidase in diabetics on diagnosis and subsequent treatment, and stable insulin dependent diabetics.

N-Acetyl-beta-D-glucosaminidase (NAG) activity has been measured in the serum and urine of diabetics. Results have shown significantly higher levels of serum NAG in newly diagnosed diabetics (945 +/- 372 units/ml) compared to non-diabetic controll (668 +/- 225, p less than 0.005) and the levels were reduced by treatment (778 +/- 218, p less than 0.05). Changes occurred in the same direction when urinary NAG was measured falling from a mean of 572 +/- 298 units/mg urinary creatinine, on diagnosis to 291 +/- 176 after treatment (p less than 0.005), as compared with 177 +/- 86 in non-diabetic controls. Established insulin-treated diabetics had a urinary NAG activity of 461 +/- 440 and a serum NAG activity of 790 +/- 245. No correlation was found between urine NAG activity and urine glucose (r = 0.315), or serum NAG and serum glucose (r = 0.273). An assessment of this enzyme is made in relation to early microangiopathy.

Acetylglucosaminidase↗
PubMed1977

Maternal plasma glucose and free fatty acid concentrations related to infant birth weight.

A new and specific method is used for the measurement of plasma free fatty acids (FFA) in pregnancy. Fasting plasma FFA and glucose concentrations were measured serially in twenty normal and twelve overweight women in pregnancy and related to infant birth weight. Large variation between individuals was noted for FFA and no change was found with advancing gestation. Studies of the day-to-day variation in the same women at 20 and 36 weeks gestation showed wide variations in concentrations. No significant change in glucose concentration was noted with advancing gestation, but postnatal values were significantly higher. Small variability of glucose concentrations was noted in both the serial and day-to-day studies. In normal-weight women a positive correlation between the observed birth weight of their infants and the fasting plasma glucose levels was found at 20 and 40 weeks and also with the mean of 5 levels measured in pregnancy. No similar correlation was found for the group of overweight women.

Adolescent↗