Incidence and follow-up of persistent lung perfusion abnormalities as a result of suspected air trapping or microthrombosis in non-hospitalised COVID-19 patients during the early half of the pandemic - experience in a tertiary institution in South Afr.

BACKGROUND: Available clinical data have revealed that COVID-19 is associated with a risk of pulmonary microthrombosis and small airway disease, especially in patients with severe disease. These patients present with persistent pulmonary symptoms after recovery, with ventilation and perfusion abnormalities present on several imaging modalities. Few data are available on the occurrence of this complication in patients who earlier presented with a milder form of COVID-19, and their long-term follow-up. OBJECTIVE: To assess the incidence of persistent lung perfusion abnormalities as a result of suspected air trapping or microthrombosis in non-hospitalised patients diagnosed with COVID-19. The long-term follow-up of these patients will also be investigated. METHODS: This was a retrospective study conducted at the nuclear medicine department of Universitas Academic Hospital, Bloemfontein. We reviewed the studies of 78 non-hospitalised patients with SARS-CoV-2 infection referred to our department from July 2020 to June 2021 for a perfusion-only single-photon emission computed tomography/computed tomography (SPECT/CT) study or a ventilation perfusion (VQ) SPECT/CT study. All 78 patients were suspected of having pulmonary embolism, and had raised D-dimer levels, with persistent, worsening or new onset of cardiopulmonary symptoms after the diagnosis of COVID-19. RESULTS: Seventy-eight patients were studied. The median (interquartile range) age was 45 (41 - 58) years and the majority (88.5%) were females. Twenty-two (28.2%) of these patients had matching VQ defects with mosaic attenuation on CT. All 9 of the patients who had follow-up studies had abnormalities that persisted, even after 1 year. CONCLUSION: We confirm that persistent ventilation and perfusion abnormalities suspicious of small airway disease and pulmonary microthrombosis can occur in non-hospitalised patients diagnosed with a milder form of COVID-19. Our study also shows that these complications remain present even 1 year after the initial diagnosis of COVID-19.

Incidence and follow-up of persistent lung perfusion abnormalities as a result of suspected air trapping or microthrombosis in non-hospitalised COVID-19 patients during the early half of the pandemic ­ experience in a tertiary institution in South Africa

Available clinical data have revealed that COVID-19 is associated with a risk of pulmonary microthrombosis and small airway disease, especially in patients with severe disease. These patients present with persistent pulmonary symptoms after recovery, with ventilation and perfusion abnormalities present on several imaging modalities. Few data are available on the occurrence of this complication in patients who earlier presented with a milder form of COVID-19, and their long-term follow-up. Objective. To assess the incidence of persistent lung perfusion abnormalities as a result of suspected air trapping or microthrombosis in non-hospitalised patients diagnosed with COVID-19. The long-term follow-up of these patients will also be investigated. Methods. This was a retrospective study conducted at the nuclear medicine department of Universitas Academic Hospital, Bloemfontein. We reviewed the studies of 78 non-hospitalised patients with SARS-CoV-2 infection referred to our department from July 2020 to June 2021 for a perfusion-only single-photon emission computed tomography/computed tomography (SPECT/CT) study or a ventilation perfusion (VQ) SPECT/CT study. All 78 patients were suspected of having pulmonary embolism, and had raised D-dimer levels, with persistent, worsening or new onset of cardiopulmonary symptoms after the diagnosis of COVID-19. Results. Seventy-eight patients were studied. The median (interquartile range) age was 45 (41 - 58) years and the majority (88.5%) were females. Twenty-two (28.2%) of these patients had matching VQ defects with mosaic attenuation on CT. All 9 of the patients who had follow-up studies had abnormalities that persisted, even after 1 year. Conclusion. We confirm that persistent ventilation and perfusion abnormalities suspicious of small airway disease and pulmonary microthrombosis can occur in non-hospitalised patients diagnosed with a milder form of COVID-19. Our study also shows that these complications remain present even 1 year after the initial diagnosis of COVID-19.

The Association between Tumour Markers and Meta-iodobenzylguanidine Scans in South African Children with High-risk Neuroblastoma.

AIMS: Diagnostic and post-induction 123I-meta-iodobenzylguanidine (123I-mIBG) scans have prognostic significance in the treatment of neuroblastoma, but data from low- and middle-income countries are limited due to resource constraints. The aim of this study was to determine the association between neuroblastoma-associated tumour markers (lactate dehydrogenase [LDH], ferritin and MYCN amplification) and 123I-mIBG scans (modified Curie scores and metastatic disease patterns) in predicting complete metastatic response rates (mCR) and overall survival. MATERIALS AND METHODS: Two hundred and ninety patients diagnosed with high-risk neuroblastoma in South Africa between January 2000 and May 2018 and a subanalysis of 78 patients with diagnostic 123I-mIBG scans were included. Data collection included LDH, ferritin and MYCN amplification at diagnosis. Two nuclear physicians independently determined the modified Curie scores and pattern of distribution for each diagnostic and post-induction 123I-mIBG scans with high inter-rater agreement (r = 0.952) and reliability (K = 0.805). The cut-off values for the diagnostic and post-induction modified Curie scores of ≥7.0 (P = 0.026) and 3 (P = 0.009), respectively, were generated. The association between the tumour markers and the modified Curie score of the 123I-mIBG scans was determined using post-induction mCR and 2-year overall survival. RESULTS: Diagnostic LDH (P < 0.001), ferritin (P < 0.001) and the diagnostic modified Curie scores (P = 0.019) significantly predicted mCR. Only ferritin correlated with diagnostic modified Curie scores (P = 0.003) but had a low correlation coefficient of 0.353. On multivariable analysis, the only significant covariate for 2-year overall survival at diagnosis was LDH <750 U/l (P = 0.024). A post-induction chemotherapy modified Curie score ≤3.0 had a 2-year overall survival of 46.2% compared with 30.8% for a score >3.0 (P = 0.484). CONCLUSION: LDH, ferritin and the diagnostic 123I-mIBG scans significantly predicted mCR, but only LDH predicted 2-year overall survival. Ferritin and the modified Curie scores correlated with each other. MYCN amplification neither correlated with any aspect of the 123I-mIBG scans nor significantly predicted mCR or 2-year overall survival. LDH and ferritin are therefore appropriate neuroblastoma tumour markers to be used in low- and middle-income countries with limited or no access to mIBG scans and/or MYCN amplification studies.

The prevalence of pulmonary embolism in non-hospitalised de-isolated patients diagnosed with mild COVID-19 disease.

BACKGROUND: Pulmonary embolism (PE) is a known complication of COVID-19 disease. The mechanism of thromboembolic events appears to be stimulated by excessive thrombin production, inhibition of fibrinolysis and deposition of antiphospholipids and thrombi, as well as microvascular dysfunction in multiple vascular beds. The occurrence of PE has been well demonstrated in hospitalised patients with severe disease. Very few data are available on its incidence or prevalence in non-hospitalised patients diagnosed with a milder form of the disease. OBJECTIVES: To assess the prevalence of PE in non-hospitalised patients diagnosed with mild COVID-19 who presented with raised D-dimer levels and persistent or new-onset cardiopulmonary symptoms. METHODS: This was a retrospective study conducted in the Department of Nuclear Medicine at Universitas Academic Hospital, Bloemfontein, South Africa. We reviewed the studies of 65 non-hospitalised patients with COVID-19 referred to the department from July 2020 to January 2021 for a perfusion-only single-photon emission computed tomography/computed tomography (SPECT/CT) study or a ventilation/perfusion (VQ) SPECT/CT study. All 65 patients had raised D-dimer levels with persistent, worsening or new-onset cardiopulmonary symptoms after the diagnosis of COVID-19. RESULTS: Sixty-five patients were studied. The median (interquartile range) age was 46 (41 - 54) years and the majority (88.2%) were female. There were 22 patients (33.8%) with lung perfusion defects in keeping with PE. Two of these patients had a false-negative computed tomography pulmonary angiography (CTPA) study for PE performed the same day as their VQ SPECT/CT study. CONCLUSIONS: We confirm a high prevalence of PE in non-hospitalised patients diagnosed with mild COVID-19 who presented with raised D-dimer levels and persistent or new-onset cardiopulmonary symptoms. We recommend that irrespective of disease severity, hospitalised and non-hospitalised patients with COVID-19 presenting with persistent or new-onset cardiopulmonary symptoms and raised D-dimer levels should be investigated further for PE.

Oxygen consumption rate of Caenorhabditis elegans as a high-throughput endpoint of toxicity testing using the Seahorse XFe96 Extracellular Flux Analyzer.

Caenorhabditis elegans presents functioning, biologically relevant phenotypes and is frequently used as a bioindicator of toxicity. However, most C. elegans in vivo effect-assessment methods are laborious and time consuming. Therefore, we developed a novel method to measure the oxygen consumption rate of C. elegans as a sublethal endpoint of toxicity. This protocol was tested by exposing 50 larval stage one C. elegans individuals for 48 h (at 20 °C) to different concentrations of two toxicants i.e. benzylcetyldimethylammonium chloride (BAC-C16) and cadmium (Cd). Following exposures, the oxygen consumption rate of the C. elegans individuals were measured using the high-throughput functionality of the Seahorse XFe96 Extracellular Flux Analyzer. Dose-response curves for BAC-C16 (R2 = 0.93; P = 0.001) and Cd (R2 = 0.98; P = 0.001) were created. Furthermore, a strong, positive correlation was evidenced between C. elegans oxygen consumption rate and a commonly used, ecologically relevant endpoint of toxicity (growth inhibition) for BAC-C16 (R2 = 0.93; P = 0.0001) and Cd (R2 = 0.91; P = 0.0001). The data presented in this study show that C. elegans oxygen consumption rate can be used as a promising functional measurement of toxicity.

Microbial metabolomics: essential definitions and the importance of cultivation conditions for utilizing Bacillus species as bionematicides.

Root-knot nematodes are destructive phytopathogens that damage agricultural crops globally, and there is growing interest in the use of biocontrol based on rhizobacteria such as Bacillus to combat Meloidogyne species. It is hypothesized that nematicidal activity of Bacillus can be attributed to the production of secondary metabolites and hydrolytic enzymes. Yet, few studies have characterized these metabolites and their identities remain unknown. Others are speculative or fail to elaborate on how secondary metabolites were detected or distinguished from primary metabolites. Metabolites can be classified based on their origin as either intracellular or extracellular and based on their function, as either primary or secondary. Although this classification is in general use, the boundaries are not always well defined. An understanding of the secondary metabolite and hydrolytic enzyme classification of Bacillus species will facilitate investigations aimed at bionematicide development. This review summarizes the significance of Bacillus hydrolytic enzymes and secondary metabolites in bionematicide research and provides an overview of known classifications. The importance of appropriate cultivation conditions for optimum metabolite and enzyme production is also discussed. Finally, the use of metabolomics for the detection and identification of nematicidal compounds is considered.

Experimental investigation of two techniques of arterial microanastomosis used to manage a small-to-large diameter discrepancy.

INTRODUCTION: A limiting factor in the use of perforators as recipient vessels is the small-to-large diameter mismatch often encountered. Mismatches less than 1:1.5 may be managed by dilatation of the smaller vessel and by differentially-spaced suture bites. Beyond this ratio, little evidence exists to direct the choice of end-to-end anastomotic technique. Following in silico work and the characterisation of a rodent superficial caudal epigastric/femoral artery model, we conducted an experimental series examining two techniques - an oblique section of the smaller vessel and invaginating the smaller vessel inside the larger. MATERIALS AND METHODS: A paired design was used. To test for a difference in patency of >5% required a total of 156 animals (312 anastomoses). Side and technique were randomised. Two investigators performed the anastomoses. A single revision was permitted. Anastomoses were timed and patency was tested at one hour, one week and at six weeks. RESULTS: There was no significant difference in patency at each of the three time points (p = 0.8026, 0.2963 and 0.8137). The invagination technique was significantly faster to perform (p < 0.0001). There was a significant association between the investigator and both patency and the time taken to complete an anastomosis. Independent of the investigator, a revision was more likely to be necessary with the oblique end-to-end technique, and a revision having been performed showed a highly significant association with an anastomosis having failed at 1 h (p < 0.0001, OR 33.333). CONCLUSIONS: In the management of microarterial size discrepancy between 1:1.5 and 1:2.5, an invaginating anastomosis is faster to perform and produces comparable patency in a rat model.

@neurIST - chronic disease management through integration of heterogeneous data and computer-interpretable guideline services.

This paper presents an overview of computerised decision support for clinical practice. The concept of computer-interpretable guidelines is introduced in the context of the @neurIST project, which aims at supporting the research and treatment of asymptomatic unruptured cerebral aneurysms by bringing together heterogeneous data, computing and complex processing services. The architecture is generic enough to adapt it to the treatment of other diseases beyond cerebral aneurysms. The paper reviews the generic requirements of the @neurIST system and presents the innovative work in distributing executable clinical guidelines.

GEMSS: grid-infrastructure for medical service provision.

OBJECTIVES: The European GEMSS Project is concerned with the creation of medical Grid service prototypes and their evaluation in a secure service-oriented infrastructure for distributed on demand/supercomputing. Key aspects of the GEMSS Grid middleware include negotiable QoS support for time-critical service provision, flexible support for business models, and security at all levels in order to ensure privacy of patient data as well as compliance to EU law. METHODS: The GEMSS Grid infrastructure is based on a service-oriented architecture and is being built on top of existing standard Grid and Web technologies. The GEMSS infrastructure offers a generic Grid service provision framework that hides the complexity of transforming existing applications into Grid services. For the development of client-side applications or portals, a pluggable component framework has been developed, providing developers with full control over business processes, service discovery, QoS negotiation, and workflow, while keeping their underlying implementation hidden from view. RESULTS: A first version of the GEMSS Grid infrastructure is operational and has been used for the set-up of a Grid test-bed deploying six medical Grid service prototypes including maxillo-facial surgery simulation, neuro-surgery support, radio-surgery planning, inhaled drug-delivery simulation, cardiovascular simulation and advanced image reconstruction. CONCLUSIONS: The GEMSS Grid infrastructure is based on standard Web Services technology with an anticipated future transition path towards the OGSA standard proposed by the Global Grid Forum. GEMSS demonstrates that the Grid can be used to provide medical practitioners and researchers with access to advanced simulation and image processing services for improved preoperative planning and near real-time surgical support.

The effect of rapamycin on the healing of the ureteric anastomosis and wound healing.

Rapamycin is a potent immunosuppressive agent that also inhibits fibroblastic activity and therefore may affect the healing of various tissues. The aim of this study was to investigate the effect of rapamycin on wound healing and the healing of the ureteric anastomosis. Large White/Landrace pigs were subjected to a laparotomy and division and immediate anastomosis of the ureter. The animals were randomly allocated to receive either rapamycin or placebo. The animals were sacrificed on postoperative day 5, and strips of the skin and fascia closure and the ureteric anastomosis excised and used to determine the tensile strength, hydroxyproline levels, and histological changes. The tensile strength and the hydroxyproline levels in the ureter and fascia were lower in the rapamycin-treated animals. There was no difference in the tensile strength in the skin, although the hydroxyproline levels were lower. This study shows that healing of the ureteric anastomosis and fascia and skin closure may be impaired by rapamycin.

Effect of rapamycin on the healing of the bile duct.

Besides its potent immunosuppressive properties, rapamycin also has antitumor and antifungal effects. Rapamycin also inhibits the proliferation of fibroblasts and therefore may impair the healing of various tissues. We investigated the effect of rapamycin on the healing of the bile duct anastomosis. The study was undertaken in pigs that were subjected to a laparotomy under general anesthesia. The bile duct was mobilized and divided and immediately reanastomosed. The animals were randomly allocated to receive either rapamycin or placebo. The animals were sacrificed on the postoperative day 5, then the biliary anastomosis was excised and used to determine the tensile strength, hydroxyproline levels, and the histological changes. The tensile strength and the hydroxyproline levels in the biliary anastomosis were lower in the animals treated with rapamycin. The liver function tests were normal. These studies show that rapamycin may impair the healing of the biliary anastomosis.

Hepatic osteodystrophy in rats results mainly from portasystemic shunting.

BACKGROUND AND AIMS: In chronic liver disease, bone disease frequently develops. The contributions of the different features of liver disease such as parenchymal inflammation, portal hypertension, and portasystemic shunting on bone metabolism have not been systematically studied. The aim of this study was to identify the features of liver disease contributing to bone disease using rat models. METHODS: Parenchymal liver disease was induced by carbon tetrachloride administration, portal hypertension by partial portal vein ligation, and portasystemic shunting by end to side anastomosis of the portal vein to the inferior vena cava. Normal and sham operated surgical animals served as controls. Serum calcium, 25-hydroxy vitamin D (25-OH vit D), and osteocalcin levels, and urinary deoxypyridinoline excretion were analysed. Testosterone and oestradiol levels were determined in male and female rats, respectively. Interleukin 1, interleukin 6, and tumour necrosis factor alpha (TNF-alpha) were determined in serum. Bone density was measured in all groups and in addition, in the surgical groups, histomorphometry was performed on undecalcified specimens of the proximal tibia. The calcium content of the femurs, removed at termination and ashed, was determined. RESULTS: Early parenchymal disease and portal hypertension did not affect bone metabolism or body mass. Portasystemic shunting increased bone resorption, decreased bone formation, bone density, and trabecular bone volume which were commensurate with a reduction in body mass. TNF-alpha levels were elevated and testosterone levels were low in male portasystemic shunted rats. CONCLUSIONS: Portasystemic shunting in the rat adversely affects bone metabolism as part of a generalised catabolic state where high TNF-alpha and low testosterone and 25-OH vit D levels may play a role.

Significance of the portal vein helix.

BACKGROUND: The portal venous system plays a major role in a variety of disease processes. Although the anatomy, histology and physiology of the portal vein have been extensively studied over the last century, very little attention has been given to its unique helical structure. Previous documentation of the helical structure has been based on microscopic, macroscopic and radiological appearances. MATERIALS AND METHODS: A more refined method than the above was used to image the portal vein helix. Resin casts of the portal venous system were performed in 6 rats, 1 baboon and 1 human. RESULTS: All species had a clearly demonstrated helical structure of the portal vein situated above the splenic vein. CONCLUSION: The unique structure of the portal vein and its subsequent helical flow has been neglected in medical research. The significance of the activated portal helix and its effect on the blood flow into the liver needs further investigation.

Another method to prevent venous thrombosis in microsurgery: an in situ venous catheter.

Free-flap failure is in the order of 4 to 10 percent. Heparin is more effective at preventing venous thrombosis than arterial thrombosis. This study was undertaken to investigate the efficacy of delivering heparin at a high dose locally but low dose systemically (heparin infusion via a catheter placed proximal to the venous anastomosis) to prevent venous thrombosis in microsurgery. A model of venous thrombosis was first established by a venous inversion graft in the rat femoral vein (this was performed in seven animals and resulted in 100 percent thrombosis). Saline and heparin were delivered proximal to the inverted vein graft to assess the effect of each in preventing venous thrombosis. Flow/patency distal to the inverted vein graft was assessed by observation under the microscope, the milk test, and rate of flow (flowmeter). Saline infused via a catheter proximal to the venous inversion graft resulted in 100 percent thrombosis in 10 animals. Heparin (100 U/ml at 2 to 3 ml/hour) infused through a catheter for 2 hours proximal to the anastomosis resulted in flow in all 10 animals during the infusion. Blood was also taken before beginning the procedure (control) and after the heparin infusion distal to the anastomosis (local partial thromboplastin time) as well as in the contralateral femoral vein (systemic). The control for all animals that received heparin was <3 minutes. The systemic partial thromboplastin time after heparin infusion was <3 minutes in seven animals, 3.3 minutes in two animals, and >7 minutes in one animal. The local partial thromboplastin time distal to the inverted vein graft was >10 minutes in nine animals and 3.7 minutes in one animal. The study also had a clinical component, in which a catheter was placed in a vein of the free flap, and heparin was infused over 5 days. This technique has been used in 83 consecutive free flaps. In three recent free flaps performed on the limbs, the local partial thromboplastin time (close to the anastomosis) was raised but the systemic time was normal. This technique offers a method in preventing venous thrombosis in microsurgery. It is simple to implement and is not associated with the systemic complications of heparin.

One-stage total hepatectomy in the rat using microvascular anastomoses.

A method is described for one-stage total hepatectomy in the rat using microvascular techniques. The operation consists of creation of a side-to-side mesocaval shunt performed just distal to the renal veins, total removal of the liver with ligation of the portal vein, hepatic arteries, and the bile duct. The vena cava is reconstructed with a segment of vena cava taken from a donor animal. The procedure takes 32 +/- 5 min to complete. Blood glucose concentration was maintained by infusions of balanced salt solution containing from 0.625% to 2.5% dextrose. Mean survival time was 10.5 hr (range, 5.5 to 21.5 hr).

Allozyme and DNA sequence data support speciation of northern and southern populations of silver catfish, Schilbe intermedius (Rüppel, 1832).

Patterns of genetic variation in Schilbe intermedius were investigated due to morphological differences and taxonomic uncertainties regarding the Southern African schilbeids. A total of three populations, two Southern populations representing the former Eutropius depressirostris and a Northern population representing S. mystus, were electrophoretically analysed to determine the extent of genetic differentiation among these populations. The Northern and Southern populations were fixed for different alleles at the G3PDH-2 protein coding locus and allozyme differentiation between populations, using the 0.95 criterion, were also encountered at the PGDH-2 locus. Genetic distance values indicate greater genetic differentiation between the Northern and Southern populations compared to the two Southern populations. DNA sequence analysis of 900-1000 nucleotides of the cytochrome b gene revealed distances of 3.2-3.5% between the Schilbe/Eutropius complex. This finding, together with ingroup and outgroup analysis of evolutionary relationships, is congruent with the results from the electrophoretic analysis of the taxa. Sufficient differentiation exist between the Northern and Southern populations to regard them as distinct species.

A modified method of continuous venous anastomosis in microsurgery.

The continuous suture technique for end-to-end vascular anastomosis is cautioned against because of the risk of vessel constriction. A modified method of continuous suture for end-to-end venous microanastomosis is presented in which vessel constriction does not occur. This technique was compared with the conventional interrupted suture technique in the rat femoral vein, with each rat serving as its own control. Forty-eight Long-Evans rats were used. The mean time taken to complete the anastomosis was 9.8 minutes (range, 8-14 minutes) for the modified continuous technique and 17.7 minutes (range, 14-24 minutes) for the conventional interrupted technique (p < 0.05, independent t-test). In addition, the veins were examined under the microscope for patency and the milk test was performed on each anastomosis 30 minutes postanastomosis, and 1 week and 1 month postoperatively. Two groups of rats were sacrificed, one at 1 week and one at 1 month, and the two different anastomoses were compared using vessel morphometry in 40 rats and corrosion casts in 8 rats. All veins were patent postoperatively, as well as at 1 week and 1 month postoperatively. Vessel morphometry confirmed a similar luminal surface area in all veins examined at 1 week and 1 month. A two-way analysis of variance of vessel morphometry indicated no significant interaction between the methods used and the postoperative time (p = 0.60). The modified continuous technique is twice as quick as the conventional interrupted technique for end-to-end microvenous anastomosis and does not lead to vessel constriction.

Haemostatic and immunological sequelae of portacaval shunt in rats.

We have evaluated the link between haemostatic abnormalities and immune dysfunction in liver disease by evaluating parameters of cellular and humoral immunity in conjunction with coagulation profiles in rats following portacaval anastomosis, induction of portal hypertension by portal vein stenosis or by sham surgical procedures. Twelve weeks following surgery, portacaval shunted rats were markedly anaemic (8.9 +/- 0.6 g/dl; controls 12.3 +/- 1.4 g/dl, p < 0.05), had low plasma fibrinogen levels (0.6 +/- 0.3 g/l, controls 2.5 +/- 0.2 g/l p < 0.05) and markedly elevated fibrin(ogen) degradation products (FDP) titres (1/40-1/80; controls < 1/10. p < 0.05). Portal vein stenosed rats were less anaemic (11.5 +/- 0.8 g/dl), had near normal fibrinogen levels (2.1 +/- 0.3 g/l) but elevated FDP levels (1/40-1/80). Both portacaval shunted and portal vein stenosed rats had elevated serum IgG levels (35.1 +/- 14.1 g/l; 29.2 +/- 13.9 g/l respectively; control values 20 +/- 5.9 g/l p < 0.05 for comparison with both experimental groups). Intrinsic lymphocyte proliferation to T and B cell mitogens was markedly depressed in the portacaval anastamosed rats when compared to controls. Serum factors inhibitory to control lymphocyte proliferation were noted in the shunted rats. Phagocytosis of complement and immunoglobulin sensitised sheep RBC by Kupffer cells purified from rats that had undergone portacaval shunting was markedly reduced (p < 0.05). The increased degree of phagocytosis following exposure to LPS-endotoxin (50 micrograms/ml) was proportionate in degree to the control group. Spontaneous release of bioactive lymphocyte activating factors (IL-1 and IL-6) by purified rat sinusoidal cell populations was decreased in the portacaval shunted group, and decreased still further following stimulation with LPS (50 micrograms/ml) in vitro. The observation that many of the haemostatic and immunological abnormalities associated with chronic liver disease are present in rats with surgically created portacaval shunts or with induced portal hypertension, lends credence to the hypothesis that shunting of portal blood is, at least in part, responsible for many of the systemic manifestations associated with chronic liver disease.

Regeneration after in situ flushing of partially hepatectomised rat livers.

The effect of various components of the transplant procedure upon the regenerative process in reduced liver grafts is not known. In this study, partially hepatectomised rat liver remnants were flushed with 5 ml of either Ringer's lactate, Euro Collins solution or University of Wisconsin solution at 4 degrees C and then 5 ml Ringer's lactate at 4 degrees C. After partial hepatectomy alone, the peak increase in thymidine kinase was measured at 24 hours (36,021 +/- 8,060 disintegrations per minute per milligram protein; the mitotic index was 25 +/- 7). In all the groups in which the remnant was flushed, peak thymidine kinase and mitotic index were measured at 48 hours. The pattern of ornithine decarboxylase activity was disorganised in all groups. Flushing of the liver remnant therefore delays the regenerative response by 24 hours. In large animals, including humans, regeneration appears to commence within the first 5 days after resection. A comparable delay doubling this time might coincide with the onset of rejection and further compromise liver function.

The effect of administration of FK506 on delayed regeneration in flushed partially hepatectomized livers.

It has been shown previously that liver regeneration after partial hepatectomy in rats is delayed if the liver is subjected to either concurrent ischaemia, flushing with cold solution, or grafting. We have shown recently that treatment with CsA preoperatively overcomes the suppressive effect of flushing and returns the regenerative response to a normal time scale. The present study was designed to investigate whether administration of FK506 would also return the observed delayed regenerative response to normal. Long-Evans rats weighing 250-350 g were subjected to standard 68% partial hepatectomy. Group 1 had no further treatment; in group 2, the liver remnant was flushed with 10 ml cold (4 degrees C) Ringers lactate solution, and in group 3, FK506 (1 mg/kg/day) was administered by intramuscular injection for 3 days before the partial hepatectomy and flushing as in group 2; a final dose was given after completion of the procedures. Animals were killed in sets of 6 per group at 4, 24, 48, 72, and 96 hr after surgery and blood samples were taken for measurement of plasma aspartate amino-transferase. Liver biopsies were analyzed for measurement of thymidine kinase and ornithine decarboxylase activity and for counting of mitotic figures. While the highest recorded thymidine kinase activity occurred in group 1 at 24 hr, this was delayed to 48 hr in both group 2 and 3 and counts remained high up to 96 hr in group 3. Mitotic indices were only significantly elevated (compared with group 1 at 96 hr), while ornithine decarboxylase activity did not correlate with these changes being significantly lower than in groups 2 and 3 at 4 hr and in group 3 also at 24 hr. Plasma aspartate aminotransferase was also significantly higher in group 3. It is concluded that the administration of FK506 preoperatively to rats subjected to partial hepatectomy and flushing did not restore the delayed regenerative response to normal but enhanced the response (as measured by thymidine kinase but not by mitotic indices) which commenced at 48 hr and was still present at 96 hr.