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Biomedical subjects

R B Allan

Publications and source records attributed to R B Allan.

14 recordsLinked to original sources
PubMed2000

Gallstone prevalence in Christchurch: risk factors and clinical significance.

AIMS: To determine the frequency, risk factors and clinical significance of gallstones in a New Zealand population. METHODS: One thousand names were randomly selected from the Christchurch electoral rolls to recruit controls for a study on the prevalence of gallstones in diabetics. Three hundred and eighteen subjects (169 females, 149 males) were recruited and in this study we analyse this control group for gallstone disease. All subjects completed a questionnaire, provided a fasting blood sample and underwent an ultrasound examination of their gallbladder unless they had previously undergone a cholecystectomy. RESULTS: Overall gallstone disease, defined as previous cholecystectomy or a positive scan for gallstones was seen in 20.75% of the 318 subjects recruited. Gallstone disease was more frequent in females (23.1%) compared to males (18.1%) but this difference was not statistically significant. For both genders there was a significant increase in gallstones with age. On univariate analysis, risk factors for gallstone disease included age, increased body mass index, family history of gallstones and decreased alcohol intake in females. However, only age and family history were significant on multiple logistic regression. There was no difference in the frequency of dyspeptic symptoms or abdominal pain between those with or without gallstones confirmed on scanning. The ratio of cholecystectomy to silent gallstones was higher in females (46.2%) than in males (22.2%). CONCLUSION: Gallstones are prevalent in the New Zealand Community (20.8% overall). Risk factors are increasing age and family history. Gallstones detected on scanning were not associated with an increased incidence of dyspeptic symptoms or abdominal pain.

Age Distribution↗
PubMed1998

Gallbladder volume: comparison of diabetics and controls.

Diabetics are known to have an increased prevalence of gallstones. The aim of this study was to investigate whether diabetics have increased gallbladder volumes that would predispose to stasis, nucleation of cholesterol crystals, and gallstone formation. The gallbladder volume of 271 diabetic subjects and 277 controls was determined by ultrasound using the ellipse formula. Gallbladder volume was also determined by the sum of the cylinders method in 143 cases with a strong correlation (r = 0.89) between the two methods. Using analysis of variance, gallbladder volume was influenced by both diabetic type (NIDDM = 33.68 cm3, IDDM = 26.84 cm3, controls = 29.05 cm3; P = 0.018) and the presence of gallstones (gallstones = 32.04 cm3, no gallstones = 27.58 cm3; P = 0.018). The variation in gallbladder volume between NIDDM, IDDM, and control subjects was influenced by the presence of gallstones (P = 0.024, interaction term from ANOVA). Significant differences (P < 0.001) were only found between NIDDM vs IDDM and NIDDM vs control in the nongallstone group (NIDDM = 34.33 cm3, IDDM = 25.08 cm3, control = 25.17 cm3). Males had significantly larger gallbladder volumes than females: 31.98 cm3 vs 27.74 cm3 (P = 0.023). After the inclusion of BMI, HDL cholesterol, triglyceride, and age in a statistical model with gender and diabetic type in those without gallstones, significant differences were still found between NIDDM and IDDM (P = 0.013) and NIDDM and controls (P = 0.005), demonstrating that NIDDM is an independent predictor for increased gallbladder volume.

Adult↗
PubMed1998

Dissolution of gallstones with simvastatin, an HMG CoA reductase inhibitor.

The aim of this study was to determine whether 12 months of therapy with Simvastatin, an HMG CoA reductase inhibitor, would dissolve gallstones. Twenty-seven subjects entered the study, all had a fasting oral cholecystogram, ultrasound examination, and fasting serum lipids prior to therapy. In addition, 22 subjects had their gallbladder ejection fraction, after CCK, determined by radionucleotide scanning. Eleven subjects had the cholesterol saturation index (CSI) of bile calculated before and at the end of 12 months of therapy. Of the 27 subjects, 26 completed 12 months of treatment with Simvastatin 20 mg daily. There was a significant fall in the total serum cholesterol (27%, P < 0.0001), LDL cholesterol (31%, P < 0.0001), triglyceride (34%, P < 0.0001) but no change in HDL after 12 months of therapy. Simvastatin treatment resulted in a 28% fall in the CSI of bile at the end of therapy (P < 0.01). The concentrations of individual bile acids did not change with therapy, and apart from a slight but significant increase in arachidonate, there were no other significant changes in the fatty acid composition of the biliary phospholipids. After 12 months of Simvastatin therapy there was a small decrease in the gallstone diameter but complete dissolution of gallstones was not achieved in any subjects. In conclusion 12 months of therapy with Simvastatin was effective in lowering the serum lipids and the CSI of bile but was not effective in dissolving gallstones.

Adult↗
PubMed1998

Gallbladder polyps: prospective study.

The aim of this study was to describe the natural history of gallbladder polyps. Thirty-eight subjects who had been previously identified as having gallbladder polyps in an epidemiologic study of gallstone prevalence in 627 diabetic subjects and matched controls were followed longitudinally. Follow-up sonograms were obtained on 33 and 22 of the 38 subjects at 2 and 5 years, respectively. Prevalence for gallbladder polyps in this population was 6.7%, with a marked male predominance (odds ratio 2.3). No statistical difference in prevalence was found between diabetic subjects and nondiabetic controls. Ninety percent of the polyps were less than 10 mm in diameter, with no polyp being larger than 12 mm. During the follow-up period no changes suggestive of malignant transformation were observed. In conclusion, we found that gallbladder polyps were relatively common and that few significant changes occurred over a 5 year period. In asymptomatic subjects in whom gallbladder polyps less than 10 mm in diameter are found incidentally, the likelihood of malignant transformation is low.

Adult↗
PubMed1997

Vesicoureteric reflux in the newborn: relationship to fetal renal pelvic diameter.

There has been a low yield of primary vesicoureteric reflux (VUR) from screening the fetal urinary tract during obstetric sonography. We sought to determine whether changing the cut-off level of fetal renal pelvic diameter from 10 mm to 4 mm would improve the yield of VUR. In a prospective community-based study, a fetal renal pelvic diameter of 4 mm or more on a transverse view of the fetal renal hilum at obstetric sonography after 16 weeks' gestation was found in 426 fetuses from 9,800 consecutive pregnancies. After birth, renal sonography was performed on 386 of the 426 babies. Of the 386 babies, 264 (187 boys) had a voiding cystourethrogram (VCUG) at a mean age of 9 weeks. Primary VUR was detected in 33 (16 boys) of the 264 infants (13%), and secondary VUR in another 5 (2%). Only 5 of the 33 (15%) babies with primary VUR would have been detected if a cut-off point of 10 mm for fetal renal pelvic diameter had been used. The prevalence of reflux was similar at each cut-off level of antenatal renal pelvic diameter from 4 to 10 mm. Neither calyceal nor ureteric dilatation was helpful in differentiating those with from those without VUR. The postnatal renal sonogram did not distinguish whether reflux was present or not. More infants with primary VUR, particularly girls, were found by changing the cut-off point for fetal renal pelvic diameter from 10 mm to 4 mm, and performing a VCUG on all such infants even if the postnatal renal sonogram was normal. Of the 33 infants with primary VUR, 9 (27%, 5 boys) had an abnormal dimercaptosuccinic acid scan. Our findings support the screening of the obstetric population for a fetal renal pelvic diameter of 4 mm or more, and then investigating the infants for VUR after birth.

Female↗
PubMed1996

Prevalence of gallbladder disease in diabetes mellitus.

A study was undertaken to compare the prevalence of gallstone disease (gallstones observed on ultrasound or history of cholecystectomy) in 308 diabetics and 318 controls. There was a higher prevalence of gallstone disease (GSD) in diabetics (32.7%) compared to controls (20.8%; P < 0.001 chi-squared test). However, when gender was taken into account, the difference was only significant in females (diabetics 41.8% versus controls 23.1%; P < 0.001). Analysis by type of diabetes revealed that subjects with non-insulin-dependent diabetes mellitus (NIDDM) had a higher prevalence of GSD than controls for both genders: males-controls 18.1%, NIDDM 33.3% (P < 0.05), IDDM 15.6% ns; females-controls 23.1%, NIDDM 48.6% (P < 0.001), IDDM 36.3% (P < 0.05). On univariate analysis the following risk factors were associated with gallstones (P < 0.1): increased age, body mass index (BMI), triglycerides, LDL cholesterol, decreased HDL cholesterol, alcohol intake, family history of GSD, and female parity > 3. Using stepwise multiple, logistic regression, the following variables were identified as independently predictive of gallstones for each gender/diabetic combination: Males-NIDDM (N = 54), increased age, and decreased HDL; IDDM (N = 90), age and family history; Females-NIDDM (N = 74), increased age, diabetes, increased BMI, and decreased alcohol; IDDM (N = 91), increased BMI, age, decreased alcohol and family history. The proportion of subjects who underwent cholecystectomy was higher in females (46.7%) compared to males (21.7%; P < 0.01) but there were no differences between diabetics and controls in either sex. In conclusion, there was a higher prevalence of GSD in diabetics compared to controls. However, GSD is multifactorial and only in NIDDM females was diabetes an independent risk factor. The proportion of diabetics and controls with GSD who underwent cholecystectomy was equivalent.

Adolescent↗
PubMed1995

Diagnosis of obstructive hydronephrosis in infants: comparison sonograms performed 6 days and 6 weeks after birth.

OBJECTIVE: The purpose of this study was to compare the usefulness of renal sonograms obtained 6 days and 6 weeks after birth in differentiating obstruction from nonobstruction in patients with antenatal pyelocaliceal dilatation shown by sonography and to establish sonographic criteria to determine the degree of postnatal pyelocaliceal dilatation that warrants further investigation. MATERIALS AND METHODS: Criteria for an infant to enter the study were fetal pyelectasis of 4 mm or greater, two postnatal sonograms with the second showing persisting pyelectasis extending at least into the infundibula, and a voiding cystourethrogram showing normal findings. One hundred thirty kidneys in 100 infants met the study criteria. The first postnatal sonogram was obtained at a mean age of 6 days (range, 1-14 days) and the second at a mean age of 6.6 weeks (range, 3-16 weeks). The degree of pyelectasis was measured in the anteroposterior direction on the transverse postnatal sonograms. The diagnosis of obstruction was made by excretory urography in 99 infants and nephrostography in one infant. Kidneys were categorized as definitely obstructed, possibly obstructed (anatomic features of obstruction on excretory urogram but functionally not obstructed), or not obstructed. Receiver-operating-characteristic (ROC) curves based on renal pelvic diameters were plotted for both sonograms; the ability to detect definite obstruction or possible obstruction was compared for the two time periods; and optimal cutoff points were determined. RESULTS: The mean diameter of the renal pelvis was not significantly different between the sonogram obtained at 6 days and the sonogram obtained at 6 weeks for the 86 nonobstructed kidneys. For the 27 kidneys that were obstructed, the mean pelvic diameter increased from 18 mm (range, 5-54 mm) on the sonogram obtained at 6 days to 22 mm (range, 11-60 mm) on the sonogram obtained at 6 weeks. The mean pelvic diameter of 17 kidneys categorized as possibly obstructed increased from 6 mm (range, 0-11 mm) to 10 mm (range, 6-20 mm) between the first and second sonograms. The ROC curves for all sonograms obtained at 6 weeks provided cutoff points with greater sensitivity and specificity than did the curves for the sonograms obtained at 6 days. The optimal cutoff points were 6 mm for possible obstruction (sensitivity, 100%; specificity, 57%) and 11 mm for definite obstruction (sensitivity, 100%; specificity, 57%) and 11 mm for definite obstruction (sensitivity, 100%; specificity, 96%). CONCLUSION: Renal obstruction may be underestimated or missed on a renal sonogram obtained 6 days after birth. A sonogram obtained 6 weeks after birth is more specific for detecting obstruction.

Female↗
PubMed1992

Placental compressibility: implications for indirect diagnosis of posterior placenta previa.

A number of problems beset the indirect diagnosis of posterior placenta previa using transabdominal ultrasound. We add a new potential complicating factor. In 128 pregnancies at or beyond 30 weeks' gestation, measurements were taken from the fetal skull to the maternal sacrum before and after compression. Up to 69% compressibility of the placenta was found in vivo and in vitro. Modified fetal skull to maternal sacrum measurement criteria were devised from the results. Placenta previa is highly unlikely if the measurement from the fetal skull to maternal sacrum is less than 10 mm before compression or less than 7 mm after compression. Placenta previa is probable if the measurement is greater than 20 mm before compression or greater than 15 mm after compression. In 40% of the cases, posterior placenta previa could not be excluded. We conclude that placental compressibility is an additional confounding problem for indirect ultrasound assessment of posterior placenta previa and that indirect assessment should be attempted only if maneuvers to image the lower uterine segment directly are unsuccessful.

Female↗
PubMed1992

Efficacy of fetal part elevation to visualise internal cervical os.

The diagnosis or exclusion of placenta previa is best achieved by direct visualisation of the relationship of the lower edge of the placenta to the internal cervical os. In later pregnancy, the presenting fetal part frequently obscures this area. Elevation of the presenting part was attempted in 56 consecutive pregnancies of greater than 30 weeks gestation, with a success rate of 71%. This confirms that in a minority of pregnancies, other manoeuvres or ultrasound techniques are necessary to visualise the lower placental margin directly.

Female↗
PubMed1978

Binding of protein chemotactic factors to the surfaces of neutrophil leukocytes and its modification with lipid-specific bacterial toxins.

The binding to neutrophil leukoyctes of human serum albumin (HSA), which is chemokinetic for leukocytes, i.e. influences their rate of locomotion, and of alkali-denatured HSA, which is chemotactic for leukocytes, i.e. influences their direction of locomotion, was studied. Native serum albumin showed low affinity binding to the neutrophil surface. Denatured serum albumin showed saturable binding with a Ka of approximately 1-(6) litres per mole to about 10(6) binding sites per cell. Another protein chemotactic factor, alpha5-casein, gave similar binding. These results exclude that chemotactic reactions to denatured proteins are mediated in a completely non-specific manner and suggest the presence on the cell of a restricted number of defined recognition sites. Binding was reduced following treatment of the cells with either of two lipid-specific bacterial toxins, perfringolysin, the theta-toxin of Clostridium perfringens, an oxygen-labile cholesterol-specific toxin, and Staphylococcus aureus Sphingomyelinase C. Both have previously been shown to reduce chemotactic reactions and both were used at doses which did not reduce cell viability. These results suggest an important, and possiblly direct, role for membrane lipid in the binding sites for chemotactic factors. Visual analysis of the behaviour of perfringolysin-treated neutrophils showed that these cells were still capable of chemotactic locomotion. The cells appeared to be less efficient than normal in detecting chemotactic gradients only when at a distance from the gradient source, a finding which is consistent with reduced binding of the chemotactic factor to the cell surface.

Bacterial Toxins↗
PubMed1977

Inhibition, by anaesthetic agents, of human leucocyte locomotion towards chemical attractants.

The effects of local, i.v. and volatile anaesthetic agents on locomotion of human blood leucocytes were studied in vitro. Blood neutrohpils and monocytes and PHA-activated lymphocytes were allowed to migrate in filters towards standard chemotactic agents and the effect of adding anaesthetic agents to the system was measured. The results showed that locomotion of all cell types was depressed reversibly by all classes of anaesthetics used at clinical concentrations. The pattern of depression varied according to the cell type under study and the class of anaesthetic used. The action of anaesthetics on chemically stimulated locomotion of leucocytes was analysed. It was concluded that the principal action of these drugs is primarily on the mechanism of locomotion itself, rather than on the capacity of the cells to detect and respond to concentration gradients of attractants. Serum albumin can protect against the inhibitory action of anaesthetics.

Anesthetics↗