Rectal suction biopsies to diagnose Hirschsprung's disease in a low-resource environment - optimising cost-effectiveness.

BACKGROUND: The diagnosis of Hirschsprung's disease (HD) by rectal suction biopsy (RSB) has cost implications that could be reduced by ascertaining the optimal number of specimens required. The aim was to audit our experience to optimise cost-effectiveness. METHODS: Medical records of all patients who underwent an RSB between January 2018 and December 2021 were reviewed. In 2020, we transitioned from using the Solo-RBT to the rbi2 system (requiring single-use cartridges). Descriptive statistics were reported and a comparative analysis of the diagnostic efficacy of the Solo-RBT versus the rbi2 system was performed. The cost of consumables was calculated according to the number of specimens submitted. RESULTS: Of 218 RSBs, 181 were first and 37 were repeat. The mean age at biopsy was 62 days (IQR 22-65). An average of two tissue specimens were obtained per biopsy. Of the 181 first biopsies, 151 were optimal and 30 suboptimal. HD was confirmed in 19 (10.5%) of the patients. Amongst biopsies where a single specimen was obtained, 16% were inconclusive, compared to 14% with two specimens and 5% with three specimens. The cartridges for the rbi2 system cost R530. If two cartridges are used at initial biopsy the total cost is double of a single tissue specimen sent for initial biopsy, and two specimens sent for repeat biopsies. CONCLUSION: In a low-resource setting, selecting the appropriate RSB system and obtaining a single specimen is sufficient to diagnose HD. Patients with inconclusive results should undergo a repeat biopsy where two specimens are obtained.

Outcomes of Kasai hepatoportoenterostomy in children with biliary atresia in Johannesburg, South Africa.

BACKGROUND: Without timely surgical intervention, most children with biliary atresia (BA) are not expected to live beyond 2 years of age. The initial intervention, the Kasai hepatoportoenterostomy (KPE), aims to achieve biliary drainage. Liver transplantation (LT) is performed if jaundice fails to clear or when biliary cirrhosis occurs. In under-resourced South African (SA) academic state hospitals, KPE procedures are the standard of care for the majority of children with BA, but LT is becoming more routinely available. OBJECTIVES: To describe the outcomes of children with BA undergoing KPE, and to identify presenting clinical, laboratory and histological features that were associated with a more favourable outcome. METHODS: All children with BA who underwent KPE between January 2009 and June 2012 at the Johannesburg academic-hospital complex were included. Clinical and laboratory parameters, including paediatric end-stage liver disease (PELD) score at the time of KPE, liver histology fibrosis score, clearance of jaundice at 6 months and 24-month survival were determined. RESULTS: Of 70 children with BA diagnosed during the study period, 43 (61.4%) underwent KPE, but only 12 (27.9%) achieved early resolution of jaundice. By 24 months, 14 (32.6%) of 43 children undergoing KPE were alive with their native liver, and 2 (4.7%) other children underwent LT. PELD score <15 and early resolution of jaundice, but not age at surgery or histological fibrosis score, predicted a favourable outcome. CONCLUSION: Children with BA undergoing KPE in SA state hospitals have a poor prognosis. The PELD score at the time of KPE best predicts 24-month survival.

Gadolinium-DTPA-enhanced magnetic resonance imaging of the isolated rat heart after ischemia and reperfusion.

The objective of this study was to assess the potential of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) to identify myocardial ischemia and reperfusion in the isolated rat heart model. Ischemia was induced by reducing the perfusion pressure from 80 to 30 mm Hg for 2 hours. Hearts were not reperfused, or were reperfused for 20 minutes or for 2 hours. Perfusion was performed with Evans blue dye and/or Gd-DTPA for 3 minutes. Twenty isolated rat hearts were perfused according to the Langendorff method, and divided into five groups according to the perfusion status and the use of Gd-DTPA and/or Evans blue as perfusion markers. The Evans blue distribution in the hearts was assessed by point-counting volumetry. The Gd-DTPA distribution was assessed by magnetic resonance microimaging at 6.3 T field strength. Evans blue staining clearly identified areas with "no flow" or "no reflow." Perfusion with Gd-DTPA enhanced signal intensity significantly, both in ischemic and reperfused myocardium. Signal intensity in hearts reperfused for 2 hours was increased significantly compared to nonreperfused ischemic hearts, but not to ischemic hearts reperfused for 20 minutes. Magnetic resonance imaging with the aid of Gd-DTPA can identify ischemia and reperfusion in the isolated rat heart, dependent on residual perfusion.

Extrinsic activation of human coagulation factors IX and X on the endothelial surface.

In previous kinetic studies, the catalytic efficiency of the activation of human coagulation factors IX and X by factor VIIa in the presence of purified tissue factor apoprotein was found to be essentially equal. These activation reactions were now studied on the surface of human umbilical vein endothelial cells. The cells were stimulated with endotoxin to express tissue factor. This tissue factor activity was saturable with factor VIIa and could be inhibited by rabbit antibodies against human tissue factor apoprotein. Only stimulated cells supported factor VIIa activity. No difference in the reactivity of factor VII and VIIa was observed in the presence of factor X, due to rapid feedback activation of factor VII by factor Xa. However, the activation of factor IX by factor VII shows a 10 min lag-phase, which reflects that the activation of factor VII by factor IXa is a less efficient process. The kinetic parameters for the factor VIIa dependent activation of factor IX and factor X on the endothelial surface were: Km 0.09 microM, Vmax 0.13 pmol/min, and Km 0.071 microM, Vmax 0.41 pmol/min, respectively. The same ratio between the Vmax for factor X and factor IX activation was observed as in a cell free system. However, the Km of factor IX was 4-fold higher on the endothelial surface than in the cell free system. Together, these kinetic parameters will favour factor X activation 5-fold over factor IX activation at physiological concentrations of these proteins. The activation of factor X by factor VIIa on the endothelial surface was characterized by a short lag-phase, which was absent in factor IX activation.(ABSTRACT TRUNCATED AT 250 WORDS)

Delayed recovery of homogeneous perfusion distribution in isolated rat heart after vasodilatation induced by alpha 1 adrenoceptor blockade during postischaemic reperfusion.

The purpose of this study was to investigate whether vasodilatation induced by doxazosin, an alpha 1 adrenoceptor blocker, during postischaemic reperfusion was able to accelerate reflow in unperfused myocardium. Isolated isovolumetrically beating rat hearts were exposed to global ischaemia by perfusion at 15 mm Hg for 2 h, resulting in an end ischaemic coronary flow rate of 2.3 (SD 1.7)% of preischaemic value, and an unperfused myocardial volume of 71.8(4.3)% of total myocardial volume. Subsequent reperfusion at 80 mm Hg for 2 h produced a partial recovery of coronary flow rate of 41(6)% in the absence of doxazosin and a complete recovery [97(28)%] in the presence of doxazosin 2 mumol.litre-1. Surprisingly, doxazosin induced vasodilatation retarded the disappearance of "no reflow" during reperfusion: after 3 h of reperfusion the volume of unperfused myocardium was 14.3(5.5)% v 1.5(1.7)% in the control group (p less than 0.005). Assessed histologically the regions of "no-reflow" were localised predominantly in the subendocardium. In the presence of doxazosin, left ventricular end diastolic pressure during reperfusion was twice as high as in the control group, indicating pronounced subendocardial compression. The mechanism underlying prolonged subendocardial "no-reflow" in the presence of doxazosin during postischaemic reperfusion is a compressive action of dilated (sub)epicardial vessels on the vasculature in the unperfused subendocardial regions ("hydraulic" or "erectile" effect of increased vascular volume). Thus coronary vasodilatation induced by alpha 1 adrenergic receptor blockade during postischaemic reperfusion delays the recovery of homogeneous transmural perfusion distribution.

Diltiazem (0.5 mg/l) decreases coronary vascular resistance during reperfusion, but not during low flow ischemia, in the isolated perfused rat heart.

Isolated rat hearts underwent low flow perfusion with a perfusion pressure of 15 mmHg for two hours followed by reperfusion at a perfusion pressure of 80 mmHg for two hours. In these severely damaged hearts we tested whether diltiazem (0.5 mg/l) administered during ischemia or during reperfusion had vasodilatory effects. Ischemia-induced progressive vasoconstriction was not influenced by the presence of diltiazem: during ischemia coronary vascular resistance (CVR) rose from 3.3 +/- 0.1 to 46.4 +/- 17.6 mmHg.ml-1.min in the diltiazem group and from 3.5 +/- 0.1 to 42.4 +/- 5.3 mmHg.ml-1.min in the control group (n.s.). If diltiazem was administered during reperfusion only CVR dropped from 45.7 +/- 9.2 to 4.4 +/- 1.1 mmHg.ml-1.min in the presence of diltiazem, and from 47.1 +/- 11.6 to 9.3 +/- 1.5 mmHg.ml-1.min in the control group (P less than 0.025). The disparity between diltiazem's effects during ischemia and reperfusion suggests a different mechanism of Ca2+-influx in vascular smooth muscle cells in ischemic and reperfused hearts: in reperfusion through the Ca2+-channels which are sensitive to calcium antagonists, and in ischemia through other channels, like the Na+/Ca2+ exchanger, or from intracellular calcium stores.

Reperfusion induced enzyme release: washout effect or manifestation of reperfusion damage?

Isolated isovolumically contracting rat hearts were subjected to ischaemia and subsequent reperfusion to determine whether reperfusion induced release of lactate dehydrogenase from the heart was due to washout of previously unperfused areas by reflow or a manifestation of myocardial damage occurring during reperfusion. Hearts were exposed to 2 h of ischaemia alone or to 2 h of ischaemia followed by reperfusion for at least 2 h. Below an ischaemic coronary flow rate of 40% of the preischaemic value drainage of enzymes liberated from irreversibly damaged myocytes was impaired owing to the presence of unperfused myocardium. The lactate dehydrogenase activity released during 2 h of ischaemia was maximally 60 U per heart and during 2 h of reperfusion maximally 251 U per heart (comprising together 89% of cardiac lactate dehydrogenase content). Lactate dehydrogenase activity released during reperfusion correlated with ischaemic coronary flow rate (r = -0.93). Reperfusion induced reflow of previously unperfused regions resulted in washout of liberated but trapped lactate dehydrogenase, predominantly responsible for lactate dehydrogenase release if ischaemia was severe (ischaemic flow rate below 40%). After the onset of reperfusion there was partial initial recovery of left ventricular developed pressure, with a gradual decline thereafter. In experiments in which ischaemia induced unperfused areas could be excluded--that is, at ischaemic flow rates of 40% or higher--reperfusion gave rise to lactate dehydrogenase release closely associated in time with the decline of left ventricular developed pressure. It is concluded that in this rat heart preparation reperfusion --takes place in previously underperfused (low flow) myocardium.(ABSTRACT TRUNCATED AT 250 WORDS)