Postgraduate training in environmental health.
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Education, Medical, Graduate↗
Biomedical subjects
A D Cameron
Publications and source records attributed to A D Cameron.
Portal hypertension and bleeding ileal varices after colectomy and ileostomy for chronic ulcerative colitis.
Two patients are described with chronic liver disease and portal hypertension in association with ulcerative colitis for which colectomy and ileostomy had been performed. Both patients developed bleeding from the varices situated around the ileostomy stoma and one also bled from the oesophageal varices. Each had a successful portacaval shunt performed because of this bleeding. The occurrence of such ileal varices is uncommon, but is important as a manifestation of portal hypertension. Although it can usually be easily controlled by local measures, portal-systemic shunt should always be considered, particularly as such patients are also very likely to bleed from oesophageal varices.
Adult↗
Influence of magnesium on the secretion and action of parathyroid hormone.
The interactions of serum levels of magnesium and parathyroid hormone (PTH) have been studied in a patient with hypomagnesemia and hypocalcemia following intestinal bypass surgery for obesity. When serum magnesium was low serum PTH was not stimulated by hypocalcemia. With correction of magnesium deficiency hypocalcemia was associated with elevation of serum PTH levels. Infusion of exogenous PTH induced a clearly detectable renal response in the presence of hypomagnesemia but the response was diminished when serum magnesium was elevated. In this patient it appears that hypomagnesemia suppressed parathyroid gland activity, leaving the renal action of PTH intact.
Calcium↗
Differential distribution of endothelin receptor subtypes in placentae from normal and growth-restricted pregnancies.
The endothelins (ETs) are potent vasoconstrictor peptides that bind to two distinct receptors, ETA and ETB. This study compares the localization of ETA and ETB receptors in placentae complicated by intrauterine growth retardation (IUGR) and abnormal umbilical Doppler waveform, gestationally matched controls, fetuses that were small for gestational age (SGA), and normal term placentae. Quantitative autoradiography was performed using ETA and ETB subtype-selective ligands. Both ETA and ETB receptors were expressed in the human placenta. Gestational and fetal size effects on the receptor density within stem villi were found, but no effect of abnormal placental blood flow could be demonstrated. A distinct spatial distribution of receptor subtypes within the placenta was observed. Smooth muscle cells expressed both receptors with ETA expression predominant in the proximal regions of the villous tree and ETB abundant in the periphery and decidua. Both receptors were also expressed at lower density on paravascular stromal cells in stem villi. Although these data do not demonstrate aberrant localization of ET receptors in IUGR and SGA placentae, the spatially distinct distribution of ET receptors in the human placenta suggests that ETs play a role in modulation of placental blood flow.
Adult↗
Congenital parvovirus B19 infection: experience of a recent epidemic.
OBJECTIVE: We report the management and outcome of 6 cases of non-immune fetal hydrops secondary to parvovirus B19 infection presenting over a 5-month period. METHODS: The Queen Mothers Hospital is a tertiary referral centre for fetal medicine. All cases were suspected on the basis of ultrasound evidence of hydrops. Two cases were managed conservatively owing to the presence of an active fetus with evidence of resolving hydrops. Fetal blood sampling intra-uterine transfusion and drainage of ascitic fluid were performed in 3 cases. The 6th case unfortunately resulted in an intra-uterine death prior to fetal blood sampling. RESULTS: Maternal parvovirus specific B19 was identified in all cases. Fetal parvovirus B19 IgM was identified in the 3 cases in whom fetal blood sampling was performed. A single intra-uterine transfusion was performed in these 3 cases; fetal hydrops resolved in 2 of these pregnancies progressing to the birth of a healthy baby at term, whereas 1 case was complicated by intra-uterine death. Fetal hydrops resolved in both cases managed conservatively, leading to the birth of a healthy baby at term. CONCLUSIONS: Parvovirus B19 infection should always be suspected in cases of non-immune hydrops. Conservative management will be appropriate in some cases and should involve weekly ultrasonography. The outlook for pregnancies presenting with gross hydrops remains guarded, even if intra-uterine transfusion is performed successfully.
Adult↗