Experimental study of electrolysis-induced hepatic necrosis

BACKGROUND

One of the most promising but unexplored methods for treating patients with irresectable liver tumours is electrolysis. This study examined the effect of increasing 'current dose' on the volume of the lesion induced in normal rat liver.

METHODS

A direct current generator, connected to platinum electrodes implanted in the rat liver, was used to examine the effect of (1) varying current doses from 1 to 5 coulombs and (2) electrode separation (2 or 20 mm), on the volume of liver necrosis.

RESULTS

There was a significant correlation (P < 0.001) between the current dose and the volume of necrosis produced for each electrode separation. Placing the electrodes 2 mm apart resulted in smaller total volumes of necrosis than placing them 20 mm apart when anode lesions were significantly larger than cathode lesions (P< 0.05). Liver enzymes (aspartate aminotransferase, alanine aminotransferase) were significantly raised 1 day after treatment (P < 0.001) and predicted the total volume of hepatic necrosis (P < 0.001).

CONCLUSION

Predictable and reproducible areas of liver necrosis are produced with electrolysis. If these results extrapolate to larger animal models, this technique has potential for patients with irresectable primary and secondary liver tumours.

Increased Mdm2 expression in rat brain after transient middle cerebral artery occlusion

The negative regulator of p53 transactivation, Mdm2, increased in the ischemic territory after 90 minutes of transient middle cerebral artery occlusion in spontaneously hypertensive rats compared to sham controls. Increased mdm2 mRNA was detected by semiquantitative reverse transcriptase polymerase chain reaction by 6 hours of reperfusion in the ipsilateral hemisphere. In situ hybridization histochemistry was used to localize increases in mdm2 mRNA which occurred in neurons of ischemic cortex and dorsolateral striatum. The number of labeled neurons increased by approximately 20-fold and the cells displayed five-fold increases of mdm2 mRNA in the cortex. Immunohistochemical staining for Mdm2 revealed that its mRNA was efficiently translated in the ischemic cortex, but not striatum, by 8 to 24 hours of reperfusion. Western blotting confirmed 30- to 40-fold increases in the full-length protein of 90 kd at these time points without evidence of alternative splicing. Because Mdm2 is a negative regulator of the apoptosis promoting activity of p53, increased expression of Mdm2 may be a component of a repair response in injured neurons, and supports Mdm2 being an indicator of DNA damage in the brain early after an ischemic insult in a similar way to Gadd45.

Hippocampal Myc and p53 expression following transient global ischemia

The proto-oncogene c-myc, and the tumor suppressor gene p53, encode proteins which function as transcriptional regulating factors governing cell proliferation, differentiation, and apoptosis. Recent evidence suggests that the delayed neuronal death which follows an episode of transient forebrain ischemia may involve apoptotic processes. We have therefore utilized immunohistochemistry to investigate the effects of transient global ischemia on neuronal expression of p53- and Myc-like immunoreactivities in the rodent forebrain 2, 12, 24, 48, and 72 h following reperfusion. Transient global ischemia (20 min), produced by four vessel occlusion (4-VO), initially elevated p53-like immunoreactivity in both CA1 and CA3 hippocampal subfields at 24 h of recirculation. However, distinct patterns of gene expression became evident in these regions at later time points. A pivotal difference was the persistence of ischemia-induced increases of p53- and Myc-like immunoreactivity in the CA1 region of the hippocampus. Unlike CA3 neurons where p53-like immunoreactivity subsided to basal levels by 48 h of survival, CA1 neurons continued to display increased p53-immunoreactivity 48 h post-ischemia, while Myc-like immunoreactivity was selectively elevated in CA1 neurons at this time point. Ischemia-induced increases in p53-like immunoreactivity were also detected in vulnerable regions of the amygdala, thalamus, and cortex 12 to 48 h after recirculation. Given that both p53 and Myc have been implicated in gene signalling pathways which mediate programmed cell death, our findings which demonstrate that 4-VO produces persistent elevations of p53- and Myc-like immunoreactivities in vulnerable neurons suggest that these proteins may also contribute to delayed neuronal death following an episode of transient forebrain ischemia.

Ischemia-induced CA1 neuronal death is preceded by elevated FosB and Jun expression and reduced NGFI-A and JunB levels

Alterations in levels of the immediate-early gene (IEG) proteins Fos, FosB, DeltaFosB, Jun, JunB, JunD, and NGFI-A were investigated in rat hippocampus by immunohistochemistry 2, 12, 24, and 48 h after forebrain ischemia. Transient global ischemia of 20 min, produced by four vessel occlusion (4-VO), elicited different patterns of IEG expression in vulnerable CA1 and more resilient CA3 neurons. Cell counts revealed that except for JunD and NGFI-A, immunoreactivity for all examined IEGs was initially elevated by forebrain ischemia in both CA1 and CA3 hippocampal subfields. However, distinct patterns of IEG expression became evident in these regions at later time points. The pivotal difference was the persistence of ischemia-induced elevations of FosB and Jun expression in the CA1 region of the hippocampus. Unlike CA3 neurons, where IEG immunoreactivity had subsided to basal levels by 24-48 h, CA1 neurons continued to display increased FosB- and Jun-like immunoreactivity 48 h post-ischemia. Western blot analysis revealed that elevated expression of both FosB and DeltaFosB-like proteins were responsible for the immunohistochemical detection of enhanced FosB-like immunoreactivity in CA1 neurons at 48 h. These findings are consistent with recent in vitro studies that implicate FosB and Jun in gene signalling pathways responsible for programmed cell death. In contrast to FosB and Jun, JunB expression declined significantly below basal levels in CA1 neurons at 48 h, yet remained unaltered in CA3 neurons. Given that JunB can inhibit the transactivating properties of Jun, decreased JunB levels may contribute to the apoptotic death of CA1 neurons by enhancing the transcriptional regulating activity of Jun. Also notable at 48 h was the complete loss of constitutive NGFI-A expression from CA1 neurons of ischemic animals. These findings suggest that persistent elevations in FosB and Jun expression, concurrent with reductions in JunB and NGFI-A levels, contribute to the apoptotic death of CA1 neurons after forebrain ischemia.

Immediate-early gene expression in the brain of the thiamine-deficient rat

Pyrithiamine-induced thiamine deficiency (PTD) in the rat is associated with neuronal loss in the thalamus and inferior colliculus. Recently, we were able to demonstrate the occurrence of apoptosis in the thalamus of these animals. Given that immediate-early genes (IEGs) participate in signal transduction pathways that mediate programmed cell death, the present study utilized in situ hybridization and immunohistochemistry to examine the expression of four IEGs (c-fos, c-jun, fos-B, and NGFI-A) during the progression of PTD. Elevated c-fos mRNA levels were initially observed in the posterior medial thalamus on d 12 of the deficiency. At the acute symptomatic stage (characterized by a loss of righting reflex on d 16-17), the posterior-medial thalamus exhibited increased mRNA for all genes examined, whereas the inferior colliculus demonstrated mRNA induction for c-fos, c-jun, and NGFI-A. Immunohistochemical analysis revealed that elevations of IEG mRNA associated with the acute symptomatic stage were consistently translated into protein in the thalamus. In contrast, whereas elevated Fos- and Jun-like immunoreactivity were detected in the inferior colliculus at this stage, NGFI-A-like immunoreactivity declined significantly below basal levels, suggesting a translational block. These results are consistent with our recent findings of apoptotic cell death, and indicate that differential patterns of IEG expression occur in the thalamus and inferior colliculus during PTD, which may contribute to the pathogenesis of this disorder.

D1-Receptor-related priming is attenuated by antisense-meditated 'knockdown' of fosB expression

Administration of dopamine receptor agonists to rats with unilateral 6-hydroxydopamine lesions of the nigrostriatal pathway produce changes in the denervated striatum that enable a subsequent injection to elicit more vigorous circling. The molecular basis for this behavioural phenomenon, termed priming, is unknown. D1-receptor-related priming has been associated with a profound elevation of immediate-early gene (IEG) expression in the denervated striatum. Since immediate-early genes encode known transcriptional regulating factors, this observation has led to the suggestion that IEG induction may play a role in the gene signaling pathways which mediate priming. In the present study, we addressed the role of induction of the IEG fosB in dopamine agonist-induced priming by examining whether inhibition of the synthesis of FosB proteins (FosB and DeltaFosB) by intrastriatal delivery of an antisense oligonucleotide to fosB reduced apomorphine-induced priming. Intrastriatal delivery of an antisense, but not a random, oligonucleotide to fosB 18 and 6 h before apomorphine reduced the ability of this mixed D1¿D2-like receptor agonist to prime circling induced by the specific D1-like receptor agonist SKF 38393. Immunohistochemical analysis revealed that only the antisense oligonucleotide blocked apomorphine-induced increases in FosB-like immunoreactivity in the denervated striatum. In contrast, apomorphine-induced increases in JunB-, NGFI-A- and Fos2-16-like immunoreactivities were unaffected by either the antisense or random oligonucleotides, indicating that the antisense oligonucleotide attenuated apomorphine-induced priming by selectively blocking the synthesis of FosB proteins. Taken together, these findings suggest that fosB induction in the denervated striatum plays a role in mediating D1-receptor-related priming. Dopamine replacement therapy for Parkinson's disease is often complicated by the development of dyskinetic side effects. Results from the present study suggest that D1-receptor-mediated increases in fosB expression may be involved in those intracellular events responsible for the generation of these debilitating side effects.

A review of pancreatic islet autotransplantation

The current literature suggests that following either total or subtotal pancreatectomy for chronic pancreatitis, the intraportal infusion of the purified or unpurified pancreatic digest will render approximately 50% of patients insulin independent. Early reports suggested that such a procedure might result in hepatic infarction and coagulopathies, but there have been no such complications in the last decade, suggesting that autotransplantation is now associated with low morbidity and mortality. There is an acknowledged subsequent rate of graft failure, but successful long-term insulin independence has now been documented for more than 10 years (Table 1). All centers undertaking total pancreatectomy for benign conditions should examine the possibility of islet autotransplantation, since even a background level of glucose responsiveness is likely to facilitate postoperative management considerably in this difficult group of patients. The process of pancreas dispersion and islet purification should probably be performed in specialist centers with a good understanding of the problems outlined above. While the transport of the pancreas and islets to and from such centers is possible in theory, we suggest that referral of the patient to a specialist center experienced in the surgical technique, transplantation and postoperative management of these patients might be more appropriate.

Patterns of neuronal activation during development of sodium sensitive hypertension in SHR

The effects of regular (RNa) or high (HNa) sodium diet for 3, 7, and 14 days on Fra-like immunoreactivity (Fra-LI) in the brains of Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were examined using an antibody that recognizes all known members of the Fos family (Fos, Fos-B, Fra-1, and Fra-2). Two weeks of HNa significantly exacerbated hypertension in SHR but had no effects in WKY. On RNa, compared with WKY, SHR showed higher Fra-LI in the median preoptic nucleus, supraoptic nucleus, both parts of the paraventricular nucleus, nucleus of the solitary tract, and central gray. Fra-LI in the subfornical organ did not differ between the two strains. On RNa, Fra-LI in the anterior hypothalamic area could be detected only in WKY. In osmoregulatory areas, HNa diet increased Fra-LI in both SHR and WKY to comparable extents, but in the median preoptic nucleus, Fra-LI was increased to a greater extent in SHR. HNa produced smaller increases in the subfornical organ of SHR compared with WKY. In both the parvocellular and magnocellular paraventricular nuclei, increases in Fra-LI by HNa were more pronounced in SHR than in WKY. In the anterior hypothalamic area, Fra-LI could no longer be detected in WKY on HNa, whereas it appeared in SHR. HNa increased Fra-LI in the NTS and central gray to similar levels in WKY and SHR. These results indicate that WKY and SHR differ in the pattern of neuronal activation accompanying maturation on RNa. HNa activates neurons in a number of brain areas, and the pattern of these changes also differs between WKY and SHR.

Shortness of breath and jaundice

Images

Elevation of neuronal expression of NAIP reduces ischemic damage in the rat hippocampus

We show here that transient forebrain ischemia selectively elevates levels of neuronal apoptosis inhibitory protein (NAIP) in rat neurons that are resistant to the injurious effects of this treatment. This observation suggests that increasing NAIP levels may confer protection against ischemic cell death. Consistent with this proposal, we demonstrate that two other treatments that increase neuronal NAIP levels, systemic administration of the bacterial alkaloid K252a and intracerebral injection of an adenovirus vector capable of overexpressing NAIP in vivo, reduce ischemic damage in the rat hippocampus. Taken together, these findings suggest that NAIP may play a key role in conferring resistance to ischemic damage and that treatments that elevate neuronal levels of this antiapoptotic protein may have utility in the treatment of stroke.

Distribution of neuronal apoptosis inhibitory protein-like immunoreactivity in the rat central nervous system

We have recently shown that spinal muscular atrophy (SMA), an autosomal recessive disorder characterized by motor neuron loss, is associated with deletion of a gene that encodes the neuronal apoptosis inhibitory protein (NAIP). In the present study, we have examined the distribution of NAIP-like immunoreactivity (NAIP-LI) in the rat central nervous system (CNS) by using an affinity-purified polyclonal antibody against NAIP. In the forebrain, immunoreactive neurons were detected in the cortex, the hippocampus (pyramidal cells, dentate granule cells, and interneurons), the striatum (cholinergic interneurons), the basal forebrain (ventral pallidum, medial septal nucleus, and diagonal band), the thalamus (lateral and ventral nuclei), the habenula, the globus pallidus, and the entopenduncular nucleus. In the midbrain, NAIP-LI was located primarily within neurons of the red nucleus, the substantia nigra pars compacta, the oculomotor nucleus, and the trochlear nucleus. In the brainstem, neurons containing NAIP-LI were observed in cranial nerve nuclei (trigeminal, facial, vestibular, cochlear, vagus, and hypoglossal nerves) and in relay nuclei (pontine, olivary, lateral reticular, cuneate, gracile nucleus, and locus coeruleus). In the cerebellum, NAIP-LI was found within both Purkinje and nuclear cells (interposed and lateral nuclei). Finally, within the spinal cord, NAIP-LI was detected in Clarke's column and in motor neurons. Taken together, these results indicate that NAIP-LI is distributed broadly in the CNS. However, high levels of NAIP-LI were restricted to those neuronal populations that have been reported to degenerate in SMA. This anatomical correspondence provides additional evidence for NAIP involvement in the neurodegeneration observed in acute SMA.

Local transcriptional control of utrophin expression at the neuromuscular synapse

Recently, the use of a transgenic mouse model system for Duchenne muscular dystrophy has demonstrated the ability of utrophin to functionally replace dystrophin and alleviate the muscle pathology (see Tinsley, J. M., Potter, A. C., Phelps, S. R., Fisher, R., Trickett, J. I., and Davies, K. E. (1996) Nature 384, 349-353). However, there is currently a clear lack of information concerning the regulatory mechanisms presiding over utrophin expression during normal myogenesis and synaptogenesis. Using in situ hybridization, we show that utrophin mRNAs selectively accumulate within the postsynaptic sarcoplasm of adult muscle fibers. In addition, we demonstrate that a 1.3-kilobase fragment of the human utrophin promoter is sufficient to confer synapse-specific expression to a reporter gene. Deletion of 800 base pairs from this promoter fragment reduces the overall expression of the reporter gene and abolishes its synapse-specific expression. Finally, we also show that utrophin is present at the postsynaptic membrane of ectopic synapses induced to form at sites distant from the original neuromuscular junctions. Taken together, these results indicate that nerve-derived factors regulate locally the transcriptional activation of the utrophin gene in skeletal muscle fibers and that myonuclei located in extrasynaptic regions are capable of expressing utrophin upon receiving appropriate neuronal cues.

Increases in DNA lesions and the DNA damage indicator Gadd45 following transient cerebral ischemia

Transient global or focal ischemia leads to the production of several types of lesions in the DNA backbone including alkali-labile sites, and both single-stranded (ss) and double-stranded (ds) breaks. The ds breaks result in high molecular weight fragments of 10-50 kbp that contain both 3'- and 5'-OH end-groups, suggesting that more than one endonuclease is involved. This lesioning of DNA is followed by the appearance of the damage-response indicator Gadd45 in the ischemic hemisphere following middle cerebral artery occlusion. By 6 h, gadd45 mRNA was shown to increase by semi-quantitative reverse transcriptase - polymerase chain reaction. In situ hybridization histochemistry indicated that these increases in gadd45 mRNA occurred in pyramidal neurons located on the edge of the infarcted cortex. Gadd45 immunostaining yielded similar findings with maximal protein staining detected at 18 h after occlusion. In neurons, in the infarct core with frank DNA fragmentation shown by in situ TdT-mediated dUTP-biotin nick end labeling (TUNEL) at 24 h, the Gadd45 immunostaining was not visible. Taken together, these findings suggest that Gadd45 responds to DNA damage following ischemia as part of a repair response mounted by brain cells attempting to survive the insult.

Palliation of oesophageal carcinoma using the argon beam coagulator

Oesophageal intubation occasionally fails to palliate inoperable carcinoma: some tumours are unsuitable for this procedure and others overgrow the tube. This study reports a series of nine patients (median age 79 (range 55-87) years) in whom the argon beam monopolar coagulator via a flexible endoscopic probe was used to ablate such tumours. Fourteen ablation procedures were performed. The endoscope was passed to the stomach at the end of each procedure. There were no complications; the median hospital stay was 2 (range 1-13) days. Thirteen procedures rendered the patients completely asymptomatic for a median of 6 (range 4-12) weeks. Six patients died a median of 14 (range 4-38) weeks after the first ablation, reflecting their limited life expectancy. The argon beam coagulator provides an effective alternative to laser ablation, being considerably cheaper and safer, while maintaining the minimally invasive nature of the palliation.

7-OH-DPAT differentially reverses clozapine- and haloperidol-induced increases in Fos-like immunoreactivity in the rodent forebrain

The pattern of neurons which display haloperidol-induced Fos-like immunoreactivity closely matches the distribution of striatal D2 dopamine receptors, whereas clozapine-induced Fos-like immunoreactivity occurs primarily in regions that contain high levels of the D3 dopamine receptor. These neuroanatomical correlations suggest that haloperidol and clozapine may elevate Fos-like immunoreactivity by blocking D2 and D3 receptors respectively. In order to test this hypothesis, the abilities of prior administration of the D3 receptor-preferring agonist 7-hydroxy-N,N'-di-n-propyl-2-aminotetraline (7-OH-DPAT) to competitively reverse haloperidol- and clozapine-induced increases in Fos-like immunoreactivity were compared. Administration of 7-OH-DPAT (0.05 mg/kg, s.c.) 30 min before clozapine (20 mg/kg, s.c.) produced a 60% reduction in the number of neurons that displayed clozapine-induced Fos-like immunoreactivity in the major island of Calleja, nucleus accumbens and medial aspect of the striatum, while prior administration of 0.5 mg/kg (s.c.) of 7-OH-DPAT completely reversed these increases in Fos-like immunoreactivity. In contrast, the increases in Fos-like immunoreactivity in the major island of Calleja, nucleus accumbens and striatum (medial and dorsal aspects) induced by haloperidol (0.1 mg/kg, s.c.) were only reduced by the high dose of 7-OH-DPAT (0.5 mg/kg, s.c.). Hence, clozapine-induced increases in Fos-like immunoreactivity were more readily reversed by 7-OH-DPAT than elevations in Fos-like immunoreactivity produced by haloperidol. These results suggest that D3 receptor blockade plays a larger role in mediating clozapine- than haloperidol-induced increases in Fos-like immunoreactivity.

A comparison of the use of two immunomagnetic microspheres for secondary purification of pancreatic islets

Immunomagnetic cell separation has been shown to be a highly attractive alternative to density-dependent methods for islet purification. There are two types of beads, magnetic inducible microspheres (MIMS) and Dynabeads, in this context. The aim of this study was to compare the two beads and ligands using the same method of purification. Two batches of collagenase were used. Using either monoclonal antibodies or lectins with a specificity for rat acinar tissue, the beads were used to immunomagnetically label pancreatic digest before magnetic separation. The results showed that both MIMS coated with a lectin and Dynabeads coated with an antibody removed 80% of the acinar contamination with a 70% islet yield. However, the MIMS were significantly less effective with the second enzyme, which produced larger acinar particles. In this study, although the MIMS produced the least nonspecific islet trapping, the Dynabeads coated with Leicester Department of Surgery no. 10 antibody were found to be the most efficient particle for immunomagnetic islet purification.

Long-term results of unilateral neck exploration for preoperatively localized nonfamilial parathyroid adenomas

BACKGROUND

Unilateral neck exploration for sporadic parathyroid adenomas remains a contentious policy. The morbidity is lower than for bilateral surgery, but the long-term outcome may be inferior.

METHODS

The results of a policy of unilateral neck exploration for primary hyperparathyroidism based on preoperative localization are reviewed.

RESULTS

Over a 10-year period, 89 patients were operated on, 57 undergoing unilateral neck exploration. Unilateral neck exploration significantly reduced operative time (P < 0.0001) and postoperative hypocalcaemia (P = 0.021). Over a mean biochemical follow-up of 38 months, recurrent hypercalcaemia occurred in 6% of patients, including 3.5% of those undergoing unilateral neck exploration, an additional 10% of patients were normocalcaemic with an inappropriately elevated parathormone level.

CONCLUSIONS

A policy of unilateral neck exploration can achieve comparable long-term results to more extensive bilateral surgery.

Comparison of propofol and a propofol-methohexitone mixture for induction of day-case anaesthesia

We studied 99 patients undergoing day-case urological surgery, allocated randomly to receive a sleep dose of either 1% propofol or a mixture of equal volumes of 1% propofol and 0.5% methohexitone, and thereafter a standardized anaesthetic. With the exception of minor differences in intraoperative heart rate there were no significant differences between the two groups in induction properties and complications, intraoperative variables, rate of recovery or postoperative sequelae.

Contrasting effects of chronic clozapine, Seroquel(TM) (ICI 204,636) and haloperidol administration of deltaFosB-like immunoreactivity in the rodent forebrain

We have recently demonstrated that specific neuroanatomical patterns of Fos-like immunoreactivity are predictive of atypical antipsychotic activity. However, the fact that neuroleptics must be administered chronically in order to generate both extrapyramidal side effects and an optimal therapeutic response calls into question the relevance of acute changes in Fos-like immunoreactivity for these slowly developing events. Fos-like immunoreactivity cannot be used to identify neurons activated by chronic neuroleptic administration because the increase in Fos-like immunoreactivity produced by an acute antipsychotic injection is dramatically reduced following repeated neuroleptic administration. In contrast, expression of the immediate-early gene product deltaFosB is persistently elevated in the striatum by chronic haloperidol administration. This suggests that deltaFosB-like immunoreactivity may be used to identify neurons activated by chronic antipsychotic administration. Since typical and atypical neuroleptics elevate Fos-like immunoreactivity in different regions of the forebrain acutely, the purpose of the present study was to determine whether typical (haloperidol) and atypical (clozapine, ICI 204,636) antipsychotics produce distinct patterns of elevated deltaFosB-like immunoreactivity in the forebrain after chronic administration. Administration of haloperidol (2 mg/kg/day) to rats for 19 days induced a homogeneous elevation of neurons which displayed deltaFosB-like immunoreactivity in the ventral, medial and dorsolateral aspects of the striatum. Chronic haloperidol administration did not enhance the deltaFos-like immunoreactivity in the prefrontal cortex and lateral septal nucleus. Repeated administration of clozapine (20 mg/kg/day) and ICI 204,636 (20 mg/kg/day) for 19 days elevated deltaFosB-like immunoreactivity not only in the ventral striatum but also in the prefrontal cortex and lateral septal nucleus. However, these compounds had weak effects on deltaFosB-like immunoreactivity in the dorsolateral striatum. These results suggest that a preferential action on limbic structures such as the prefrontal cortex, ventral striatum and lateral septal nucleus may account for the ability of chronic clozapine and ICI 204, 636 administration to reduce the symptoms of schizophrenia without generating extrapyramidal side effects.

No obvious advantages for thoracoscopic two-stage oesophagectomy

Thoracoscopically assisted Ivor-Lewis oesophagectomy potentially combines the pulmonary advantages of transhiatal oesophageal dissection, with the visibility and control permitted by thoracotomy. This study reviewed 17 patients who underwent this procedure with an intrathoracic anastomosis. Five patients required conversion to thoracotomy, four because of technical difficulties with the anastomosis. After operation 13 patients had radiological evidence of atelectasis, six developed a left pleural effusion and five had clinically significant pneumonia. Three patients developed an anastomotic leak, two of whom died giving an in-hospital mortality rate of 12 per cent. Median postoperative hospital stay was 12 days. Four patients developed benign anastomotic strictures requiring dilatation. The 1- and 2-year survival rates were 73 per cent (11 of 15 patients) and 63 per cent (five of eight) respectively. The use of minimal access techniques in this context does not appear to reduce the postoperative incidence of either pulmonary or anastomotic complications.

Technique for full-thickness muscle closure of laparoscopic port sites

Since the introduction of laparoscopic surgery there have been several case reports of incisional hernia at sites where laparoscopic trocars have been inserted through the abdominal wall1–5. These occur predominantly through port sites with a diameter of 10 mm or more, either through the linea alba at the umbilicus, or through more lateral defects. Fascial closure reduces the incidence but does not eliminate hernias entirely as they can occur into the subfascial space1,2. As complex laparoscopic surgery involving the use of several large ports becomes increasingly common, the incidence of this complication is likely to increase. The authors believe it is important to perform a full-thickness closure of all muscle defects 10 mm or greater in diameter.

Effects of olanzapine on regional C-Fos expression in rat forebrain

Compared to typical antipsychotic drugs, clozapine produces a unique pattern of Fos-like immunoreactive neurons in the rat forebrain. It has been proposed, therefore, that this approach may be useful in identifying other agents with clozapine's therapeutic profile. In the present study, we examined the ability of olanzapine to increase the number of Fos-like immunoreactive neurons in the striatum, nucleus accumbens, lateral septal nucleus, and prefrontal cortex. Olanzapine (5, 10 mg/kg) produced dose-dependent increases in the number of Fos-positive neurons in the nucleus accumbens and lateral septal nucleus, important components of the limbic system that may mediate some of the therapeutic actions of neuroleptics. Olanzapine also produced dose-dependent increases in the number of Fos-positive neurons in the dorsolateral striatum, an effect that correlates with the ability of neuroleptics to produce extrapyramidal side-effects. The effects of olanzapine on regional c-fos expression are not therefore identical to clozapine, which is without effect in the dorsolateral striatum. However, olanzapine-induced increases in the dorsolateral striatum were considerably smaller than those generated in the nucleus accumbens suggesting that at low, potentially therapeutic doses olanzapine may not generate significant extrapyramidal side effects. Olanzapine also increased the number of Fos-positive neurons in medical prefrontal cortex, an action unique to clozapine and a few other atypical antipsychotics. These findings are consistent with the hypothesis that olanzapine is an atypical antipsychotic in the sense that it does not produce significant extrapyramidal side-effects at low therapeutic doses. However, extrapyramidal side-effects at higher doses can be predicted by these results. Finally, olanzapine's actions in the medial prefrontal cortex may be predictive of a clozapine-like profile with respect to actions on negative symptoms in schizophrenia. Additional clinical experience with olanzapine and other new antipsychotics is required to test the validity of these hypotheses.

Chronic alterations in dopaminergic neurotransmission produce a persistent elevation of deltaFosB-like protein(s) in both the rodent and primate striatum

Using an antibody that recognizes the products of all known members of the fos family of immediate early genes, it was demonstrated that destruction of the nigrostriatal pathway by 6-hydroxydopamine (6-OHDA) lesions of the medial forebrain bundle produces a prolonged (>3 months) elevation of Fos-like immunoreactivity in the striatum. Using retrograde tract tracing techniques, we have previously shown that this increase in Fos-like immunoreactivity is located predominantly in striatal neurons that project to the globus pallidus. In the present study, Western blots were performed on nuclear extracts from the intact and denervated striatum of 6-OHDA-lesioned rats to determine the nature of Fos-immunoreactive protein(s) responsible for this increase. Approximately 6 weeks after the 6-OHDA lesion, expression of two Fos-related antigens with apparent molecular masses of 43 and 45 kDa was enhanced in the denervated striatum. Chronic haloperidol administration also selectively elevated expression of these Fos-related antigens, suggesting that their induction after dopaminergic denervation is mediated by reduced activation of D2-like dopamine receptors. Western blot immunostaining using an antibody which recognizes the N-terminus of FosB indicated that the 43 and 45 kDa Fos-related antigens induced by dopaminergic denervation and chronic haloperidol administration may be related to a truncated form of FosB known as deltaFosB. Consistent with this proposal, retrograde tracing experiments confirmed that deltaFosB-like immunoreactivity in the deafferented striatum was located predominantly in striatopallidal neurons. Gel shift experiments demonstrated that elevated AP-1 binding activity in denervated striata contained FosB-like protein(s), suggesting that enhanced deltaFosB levels may mediate some of the effects of prolonged dopamine depletion on AP-1-regulated genes in striatopallidal neurons. In contrast, chronic administration of the D1-like receptor agonist CY 208243 to 6-OHDA-lesioned rats dramatically enhanced deltaFosB-like immunoreactivity in striatal neurons projecting to the substantia nigra. Western blot immunostaining revealed that deltaFosB and, to a lesser extent, FosB are elevated by chronic D1-like agonist administration. Both the quantitative reverse transcriptase-polymerase chain reaction and the ribonuclease protection assay demonstrated that deltafosB mRNA levels were substantially enhanced in the denervated striatum by chronic D1-like agonist administration. Lastly, we examined the effects of chronic administration ofD1-like and D2-like dopamine receptor agonists on striatal deltaFosB expression in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) primate model of Parkinson's disease. In monkeys rendered Parkinsonian by MPTP, there was a modest increase in deltaFosB-like protein(s), while the development of dyskinesia produced by chronic D1-like agonist administration was accompanied by large increases in DeltaFosB-like protein(s). In contrast, administration of the long-acting D2-like agonist cabergoline, which alleviated Parkinsonian symptoms without producing dyskinesia reduced deltaFosB levels to near normal. Taken together, these results demonstrate that chronic alterations in dopaminergic neurotransmission produce a persistent elevation of deltaFosB-like protein(s) in both the rodent and primate striatum.

Selection criteria for preoperative endoscopic retrograde cholangiopancreatography in the laparoscopic era

BACKGROUND

Indicators for cholangiography were originally designed to select patients at risk for common bile duct (CBD) stones for intraoperative cholangiography.

OBJECTIVE

To refine these criteria to apply to the much more invasive procedure of preoperative endoscopic retrograde cholangiopancreatography (ERCP).

DESIGN

Retrospective review of selection criteria for ERCP in consecutive patients referred over 18 months following the introduction of laparoscopic cholecystectomy.

SETTING

Two ERCP units in adjacent teaching hospitals.

PATIENTS

Three hundred seventeen patients with gallstones and in situ gallbladders.

INTERVENTION

Common bile duct imaging at ERCP.

MAIN OUTCOME MEASURES

Abnormalities justifying ERCP.

RESULTS

Abnormalities justifying ERCP were found in 66% of patients. This group differed significantly from those with normal ducts, with more being referred with abnormal results of all liver function tests (P < .001), jaundice (P < = .001), a dilated CBD on ultrasound (P < .001), or CBD stones on ultrasound (P < .001). On the other hand, patients with normal ducts were significantly more likely to have been referred with pancreatitis (P = .003) or elevated results of individual liver function tests (P < .001). A logistic regression model using age, presence of jaundice at ERCP, levels of alkaline phosphatase and albumin, and ultrasonography showing dilated ducts or visible CBD stones was found to have a specificity of 75% and a sensitivity of 89%. Past pancreatitis or elevated results of individual liver function tests were not predictive factors.

CONCLUSION

The use of such a model rather than individual criteria would improve the selection of patients for preoperative ERCP, optimizing its role in the laparoscopic era.

Factors predicting outcome after selective ERCP in the laparoscopic era

This study assessed the outcome of 342 patients with in situ gallbladders undergoing ERCP for suspected choledocholithiasis. The result of ERCP was found to play a significant role (P < 0.0001) in determining whether patients were subsequently managed conservatively (n = 152) or underwent either laparoscopic (n = 110) or open (n = 80) surgery. Those undergoing laparoscopic surgery were noted to be younger (P = 0.0001) and were less likely to be jaundiced (P = 0.0015) or have CBD stones at ERCP (P = 0.0295). In 28 patients with CBD stones remaining after ERCP, pre- rather than postoperative timing of ERCP prevented a potential second operation. The current success rate of 85% in clearing CBD stones at ERCP cannot support a routine policy of intraoperative cholangiography followed by postoperative ERCP.

Serum gastrin levels in the pre-operative localization and surgical treatment of gastrinomas

The introduction of sensitive radioimmunoassays for gastrin has led to the earlier and more accurate diagnosis of gastrinomas and, as methods for tumour localization both pre- and intraoperatively have improved, the emphasis of surgery has changed from control of gastric acid secretion to tumour removal. We present three cases of sporadic gastrinoma who underwent exploratory laparotomy. In two cases, gastrinomas were discovered and excised resulting in cure for one patient. The third case underwent a negative laparotomy. The changes in serum gastrin levels taken during and immediately after surgery were related to the success or otherwise of tumour removal in each of the three cases. As in parathyroid surgery, with the development of rapid radioimmunoassays, the intraoperative measurement of declining serum gastrin levels will help in the early definition of surgical success supplementing frozen section and clinical judgement and improving patient management.

Laparoscopic Heller's cardiomyotomy without an antireflux procedure

The treatment of achalasia by laparoscopic Heller's cardiomyotomy may combine the minimally invasive advantages of pneumatic dilatation with the success rate and low risk of perforation of conventional surgery. The requirement for an antireflux procedure remains a contentious issue, as in conventional surgery. Nine patients underwent laparoscopic cardiomyotomy; excellent symptomatic relief was obtained in eight at follow-up between 12 and 21 months after operation. Four of these patients agreed to 24-h pH monitoring and showed no evidence of acid reflux. One patient, however, developed recurrent symptoms associated with significant acidity on monitoring. Laparoscopic Heller's cardiomyotomy without an antireflux procedure produced effective symptomatic relief in this small group of patients.

Laparoscopic Nissen fundoplication in children

Laparoscopic surgery for the definitive treatment of gastroesophageal reflux (GOR) has become an accepted alternative to conventional techniques in adults. Although relatively rare, GOR in children represents an important clinical entity with symptoms including failure to thrive, nocturnal dyspnea, and vomiting. This paper details our experience in eight children who have undergone a laparoscopic Nissen fundoplication for failed medical treatment of severe GOR. Particular attention is paid to technical aspects of the procedure and the differences between adult and pediatric techniques are emphasized. The preliminary results suggest that a laparoscopic Nissen fundoplication is a safe procedure which significantly improves reflux symptoms in children and that these results are comparable to those obtained with conventional surgery.

C-fos mediates antipsychotic-induced neurotensin gene expression in the rodent striatum

The ubiquitous inducibility of the immediate-early gene c-fos in the central nervous system has led to the search for downstream genes which are regulated by its product, Fos. Recent evidence suggests that c-fos induction by a single injection of the classical antipsychotic haloperidol may contribute to the subsequent increase in neurotensin gene expression in the rodent striatum. Consistent with this proposal, in the present study haloperidol-induced Fos-like immunoreactivity and neurotensin/neuromedin N messenger RNA were found to be expressed by the same population of striatal neurons. Moreover, inhibition of haloperidol-induced c-fos expression by intrastriatal injection of antisense phosphorothioate oligodeoxynucleotides complimentary either to bases 109-126 or 127-144 of c-fos attenuated the subsequent increase in neurotensin/neuromedin N messenger RNA. However, injection of a sense phosphorothioate oligodeoxynucleotide corresponding to bases 127-144 of c-fos did not reduce haloperidol-induced c-fos or neurotensin/neuromedin N expression. Furthermore, constitutive expression of Jun-like immunoreactivity in the striatum was not reduced by either the sense or antisense phosphorothioate oligodeoxynucleotides. Similarly, the sense and antisense phosphorothioate oligodeoxynucleotide failed to reduce proenkephalin messenger RNA, which is located in the same striatal neurons that express haloperidol-induced neurotensin/neuromedin N messenger RNA, which is located in the same striatal neurons that express haloperidol-induced neurotensin/neuromedin N messenger RNA. Lastly, haloperidol-induced increases in nerve growth factor I-A-, JunB- and FosB-like immunoreactivity and fosB messenger RNA were not decreased by intrastriatal injection of either the sense or antisense phosphorothioate oligodeoxynucleotides. These results indicate that the antisense phosphorothioate oligodeoxynucleotides attenuated haloperidol-induced neurotensin/neuromedin N expression by selectively reducing c-fos expression and emphasize the potential importance of immediate-early gene induction in the mechanism of action of this antipsychotic drug.

Use of laparoscopic instruments in conventional mobilisation of the rectum

The use of conventional instruments for dissection within confined operating fields such as the pelvis may obscure the surgeon's view, and limit his reach. The long, narrow instruments used during laparoscopic surgery, particularly the diathermy scissors can facilitate bloodless dissection under direct vision during conventional surgery, improving the accuracy of procedures such as mobilisation of the rectum.

Optimization of the magnetic field used for immunomagnetic islet purification

Purification of islets based on the physical differences in density between exocrine and islet tissue reduces islet yields and remains one of the factors limiting islet transplantation. Immunomagnetic cell separation methods provide an attractive, highly specific alternative capable of rapid, gentle, high volume cell separation, but they require modification to be applied effectively to separation of the much larger tissue fragments involved in islet purification. In this study, mAb to rat exocrine tissue were coupled to 4.5-microns magnetic beads (M450 Dynabeads), before incubation with standard aliquots of rat pancreatic digest. The effect on immunomagnetic islet purification of modifications in the magnetic field and the method of digest release into the field were investigated. The results showed that using vibration to maintain the immunomagnetically labeled digest in suspension in tissue culture medium whose density had been increased by the addition of BSA, significantly improved the purification process. When the digest suspension was slowly released and allowed to drift under gravity through a magnetic field applied across a narrow tube, the use of a quadripole of permanent magnets improved results compared with bipolar or unipolar magnetic fields. By modifying immunomagnetic cell separation techniques in this way, a median islet yield of 77% could be reliably achieved while removing 88% of the contaminating exocrine tissue. The use of such methods in human islet purification would significantly increase the yield of islets from each donor pancreas and increase the success rate of transplantation from single donors.

Does subclinical pancreatic inflammation occur after parathyroidectomy?

Pancreatitis is accepted as an uncommon complication of parathyroid surgery, but it has been suggested that up to 35% of patients may experience hyperamylasaemia after parathyroidectomy indicating subclinical inflammation of the pancreas. A series of 26 patients undergoing parathyroidectomy were studied by preoperative biochemical analyses repeated 24 and 48 h postoperatively allowing changes in calcium metabolism and serum and urinary amylase levels to be documented. Of the patients, 21 also underwent a CT scan of the pancreas between 24 and 48 h after operation. Despite highly significant changes in serum parathormone, calcium and phosphate levels postoperatively, there was no evidence in any patient of acute pancreatic inflammation or hyperamylasaemia. Twenty-one patients underwent unilateral neck exploration, and we suggest that the absence of any detectable amylase elevation supports the suggestion that such elevation may reflect an increase in salivary isoamylase as a result of extensive neck dissection, rather than reflecting a subclinical pancreatitis. The development of postparathyroidectomy pancreatitis appears to be an all or nothing phenomenon of unknown aetiology.

Radical orchidectomy and benign testicular conditions

The records of 149 patients who underwent testicular exploration for suspected malignancy were reviewed retrospectively. Malignancy was confirmed in 102 patients but benign pathology was noted in 47. Patients with benign disease were older, more likely to be Asian, gave a longer history and on examination were less likely to have a testicular mass. Increased levels of tumour markers, and ultrasonographic and operative appearance of the testis were highly predictive; with ultrasonography having a sensitivity of 100 per cent but a specificity of only 36 per cent for malignancy. Preoperative ultrasonography and an awareness of the potentially benign nature of many lesions with the use of frozen-section biopsy, where appropriate, may allow a decrease in the currently high rate of unnecessary orchidectomy without missing testicular malignancy.

D1 and D2 dopamine receptors differentially increase Fos-like immunoreactivity in accumbal projections to the ventral pallidum and midbrain

Alterations in dopaminergic neurotransmission have profound effects on neuronal expression of the putative activity marker, Fos, in both the dorsal and ventral striatum. Stimulants such as D-amphetamine and cocaine increase Fos-like immunoreactivity by enhancing the activation of D1 dopamine receptors. In contrast, neuroleptics such as haloperidol and raclopride increase Fos-like immunoreactivity by blocking striatal D2 dopamine receptors. In the dorsal striatum, D1 receptor stimulation elevates Fos-like immunoreactivity predominantly in neurons projecting to the midbrain (substantia nigra), whereas D2 receptor antagonism enhances Fos-like immunoreactivity principally in neurons projecting to the pallidum (globus pallidus). These findings are consistent with the proposal that D1 receptors are located chiefly on striatonigral neurons, whereas D2 receptors reside mainly on striatopallidal neurons. Since the nucleus accumbens (largest component of the ventral striatum) also sends projections to the midbrain (ventral tegmental area and substantia nigra) and pallidum (ventral pallidum), the present study utilized retrograde tract-tracing techniques to determine if there was a similar segregation of D1 agonist- and D2 antagonist-induced Fos-like immunoreactivity in these accumbal projections. In addition, we examined whether these relationships were the same in the core and shell regions of the nucleus accumbens. Like the dorsal striatum, D1 agonists (D-amphetamine and CY 208-243), but not D2 antagonists (haloperidol and clozapine), increased Fos-like immunoreactivity in accumbal neurons projecting to the midbrain (ventral tegmental area and substantia nigra). Also like the dorsal striatum, D2 antagonist-induced Fos-like immunoreactivity was located preferentially in accumbal neurons projecting to the pallidum (ventral pallidum). However, unlike the dorsal striatum, where the vast majority of neurons which display D1 agonist-induced Fos-like immunoreactivity project to the midbrain, nearly 50% of those neurons in the nucleus accumbens which were Fos-immunoreactive after D-amphetamine or CY 208-243 projected to the ventral pallidum. Thus, a similar number of accumbal neurons which expressed D1 agonist-induced Fos-like immunoreactivity were retrogradely labelled from the midbrain and ventral pallidum. Accumbal projections to the midbrain and ventral pallidum were retrogradely labelled with different retrograde tracers in order to determine the degree of collateralization between these pathways. Approximately 20% of retrogradely labelled neurons displayed both tracers, indicating that collateralization and damage to fibres of passage could not account for all of those cases in which D1 agonist-induced Fos-like immunoreactivity was detected in accumbal neurons projecting to the ventral pallidum.(ABSTRACT TRUNCATED AT 400 WORDS)

Making an advance directive

The introduction in Britain of advance directives--which allow a person to state in advance of becoming incompetent that they wish to take part in treatment decisions when no longer mentally competent--has now been advocated by the medical and legal establishments. The practical application of directives relating to health care would be simplified by the adoption of a standard model document together with guidelines summarising the background clinical conditions and any subsequent acute events that may make it appropriate to trigger the use of a directive. As no specific legislation exists, good communication is needed at the various stages between the drafting and implementation of directives if the system of directives is to be successful.

Induction patterns of Fos-like immunoreactivity in the forebrain as predictors of atypical antipsychotic activity

Clozapine and haloperidol produce different induction patterns of c-fos expression in the forebrain, with haloperidol increasing Fos-like immunoreactivity (FLI) in the striatum, nucleus accumbens, lateral septal nucleus and clozapine producing such effects in the nucleus accumbens, prefrontal cortex and lateral septal nucleus. Accordingly, it was deemed possible that this approach may be useful in characterizing compounds with known or suggested antipsychotic actions. We therefore examined the effects of 17 compounds considered to be either typical, or atypical, antipsychotics on FLI in the prefrontal cortex, medial and dorsolateral striatum, nucleus accumbens and the lateral septal nucleus. Consistent with the hypothesis that the prefrontal cortex may be a target for some antipsychotic actions, FLI was elevated in this structure by clozapine, ICI 204,636, fluperlapine, RMI-81,582, remoxipride, molindone, melperone and tiospirone. Likewise, the ability of all of the compounds, except for risperidone, to enhance FLI in the lateral septal nucleus suggests that this limbic region also may be an important locus of antipsychotic action. All of the compounds examined elevated FLI in the nucleus accumbens and medial striatum, indicating that potential antipsychotic activity is predicted most consistently on this basis. Neuroleptics with a clearly documented liability for producing extrapyramidal side effects (EPS) such as chlorpromazine, fluphenazine, haloperidol, loxapine, metoclopramide and molindone elevated FLI in the dorsolateral striatum. In contrast, compounds unlikely to produce EPS such as clozapine, thioridazine, risperidone, remoxipride, fluperlapine, sulpiride, melperone and RMI-81,582 either failed to increase or produced minor elevations in FLI in the dorsolateral striatum.(ABSTRACT TRUNCATED AT 250 WORDS)

Storage of pancreatic digest before islet purification. The influence of colloids and the sodium to potassium ratio in University of Wisconsin-based preservation solutions

The density-dependent purification of islets from several species of mammalian pancreata is improved by prior storage of the dispersed, collagenase-digested pancreas in suitable storage solutions, such as University of Wisconsin (UW) solution. The optimal composition of such solutions, however, is not fully established, although previous investigations have suggested separately that cellular impermeants and colloids are important components. To investigate this issue further, dispersed tissues from 7 porcine and 7 human pancreata were stored in UW or in solutions containing the impermeants lactobionate and raffinose, with either no added colloid or in the presence of the colloids hydroxyethyl starch, dextran 40, dextran 250, or Ficoll 400; hydroxyethyl starch-containing solutions in which the principal cation was sodium, rather than potassium, were also studied. Subsequent purification of islets on continuous linear density gradients of BSA was then assessed by insulin/amylase assay of gradient fractions. Islet purity was slightly reduced using solutions containing impermeants but lacking a colloid, compared with using UW. In the combined presence of impermeants and a colloid, however, islet purity was similar to that obtained with UW, and for porcine pancreata, solutions containing Ficoll 400 or dextran 40 were slightly superior to UW. Purity was not, however, influenced by the sodium to potassium ratio of storage media. In conclusion, impermeants and colloids are both essential components of solutions used to preserve pancreatic tissue before islet purification, findings which may be relevant when designing media for use during other phases of islet isolation, e.g., during collagenase digestion/density gradient purification.

D1 dopamine receptor agonist-induced Fos-like immunoreactivity occurs in basal forebrain and mesopontine tegmentum cholinergic neurons and striatal neurons immunoreactive for neuropeptide Y

The present study sought to determine whether the D1 dopamine receptor agonist CY 208-243 increases Fos-like immunoreactivity in neurochemically distinct populations of interneurons in the 6-hydroxydopamine-denervated striatum. In vivo microdialysis studies indicate that cholinergic interneurons in the striatum are excited by the administration of CY 208-243 and that this effect is potentiated by dopaminergic deafferentation. Since Fos is considered to be a marker of neuronal activity, we examined the overlap between CY-208-243-induced Fos-like immunoreactivity and striatal cholinergic interneurons labelled with the cholinergic marker enzyme choline acetyltransferase. Unexpectedly, cholinergic interneurons in the striatum were not found to express Fos-like immunoreactivity. However, D1 agonist-induced Fos-like immunoreactivity was found in neurons immunoreactive for neuropeptide Y. Consequently, the failure of cholinergic neurons in the striatum to express D1 agonist-induced Fos-like immunoreactivity does not appear to be a general property of striatal interneurons. Indeed, CY 208-243 increased Fos-like immunoreactivity in choline-acetyltransferase-positive neurons in the basal forebrain and lateral dorsal tegmental nucleus. In the case of cholinergic basal forebrain neurons, administration of CY 208-243 has been shown to enhance the release of acetylcholine from their terminals located in the frontal cortex. Thus, unlike cholinergic interneurons in the striatum, the expression of Fos-like immunoreactivity in cholinergic basal forebrain neurons is correlated with an increase in transmitter release. Choline acetyltransferase immunoreactivity was markedly reduced in cholinergic basal forebrain neurons ipsilateral to the 6-hydroxydopamine lesion. This decrease in choline acetyltransferase immunoreactivity was confined to a pocket of cortically projecting neurons located in the posterior part of the horizontal limb of the diagonal band which included the medial preoptic nucleus. Interestingly, D1 agonist-induced Fos-like immunoreactivity was located predominantly in those cholinergic neurons which displayed depressed choline acetyltransferase immunoreactivity. Since Fos is often induced as a consequence of increased activity, it is tempting to speculate that those neurons which stained weakly for choline acetyltransferase had been excited by the D1 agonist administration. Accordingly, the destruction of mesencephalic dopaminergic neurons with 6-hydroxydopamine may have deprived these cholinergic neurons of an excitatory D1 receptor-mediated drive, resulting in a reduction of choline acetyltransferase immunoreactivity. These results suggest that the degeneration of nigrostriatal dopamine neurons may contribute to the loss of cholinergic basal forebrain function in Parkinson's disease.

The effectiveness of components of University of Wisconsin solution in improving human pancreatic islet purification

The purification of human pancreatic islets before transplantation relies on the density-dependent separation of islets from exocrine fragments after collagenase digestion of the donor pancreas. The results vary among pancreases despite increasing automation of the digestion and purification processes, reflecting variations in the overlapping densities of islets and contaminating exocrine tissue. Hypothermic storage of both the pancreas and the pancreatic digest alters cell volumes and tissue densities, thereby affecting islet purification. By biochemical analysis of the isopycnic distribution of islets and exocrine tissue fragments from 23 human pancreases on linear continuous density gradients, the effect of various solutions for cold storage of pancreatic digest was studied. The use of the University of Wisconsin cold storage solution, which resulted in a significant decrease in digest volume (P = 0.006) and increase in the densities of both exocrine tissue (P = 0.001) and islets (P = 0.005), produced a significant improvement in islet purity compared with tissue culture medium (P = 0.035), predominantly due to the inclusion of a colloid, which increased the difference in density between exocrine tissue and islets. The addition of large molecular weight cellular impermeants without alteration in the concentration of permeable anions produced no effect. The results of this study support the concept that the use of solutions that minimize cell swelling throughout the process of islet purification would result in significant improvements in density-dependent islet separation, and that such solutions should contain a colloid.

Thoracoscopic oesophago-gastrectomy--a new technique for intra-thoracic stapling

A new technique for performing a standard Ivor Lewis oesophagectomy avoiding the need for a conventional right thoracotomy is described. The intrathoracic dissection and the intrathoracic anastomosis, using a conventional EEA circular staple-gun, is done thoracoscopically. Eight patients with carcinoma of the gastric cardia or distal oesophagus were prepared for a palliative Ivor Lewis two-stage oesophago-gastrectomy. The details of the technique for placing the anvil of a circular staple gun in the upper oesophagus and performing the intrathoracic stapled anastomosis are described. Intrathoracic stapling under thoracoscopic video control was successful in five of the eight patients. The three other patients received 10 cm mini-thoracotomies. All patients were transferred from the intensive care unit within 24 hours and were discharged from hospital within 14 days. There were no complications and no deaths. We believe that this procedure offers many patients better palliation with reduced morbidity because the standard right thoracotomy is avoided.

Human islet isolation--a prospective randomized comparison of pancreatic vascular perfusion with hyperosmolar citrate or University of Wisconsin solution

University of Wisconsin solution has become the most commonly used vascular perfusate during multiorgan donation world-wide. In the UK however, hyperosmolar citrate remains in common use. The purpose of this prospective randomized study was to compare the effect of systemic perfusion with UW or HOC on subsequent islet yield and purification for pancreata with short cold ischemic times. Seven pancreata were randomized to each group, with the donor age, pancreas weight, and period of cold ischemia being similar in both. Perfusion with UW was shown to inhibit collagenase digestion, and a higher concentration of this enzyme was needed to achieve comparable numbers of islets with good separation of exocrine and islet tissue after a similar period of digestion. There were no differences in the number, size, purity, or viability of islets between the two groups. In conclusion, UW solution offers no benefits over HOC for pancreata with short cold ischemic times, and because of its expense and need to use greater amounts of collagenase enzyme, we continue to use HOC.

Storage of porcine pancreatic digest prior to islet purification. The benefits of UW solution and the roles of its individual components

The aim of this study was to establish the beneficial effect of storage of pancreatic digest in University of Wisconsin solution on porcine islet purification, the mechanism of this effect, and the components of UW responsible. Ten porcine pancreata were collagenase-digested, and samples of digest were washed and stored for 1 hr in either UW or minimum essential medium at 4 degrees C, prior to separation on continuous linear density gradients of bovine serum albumin. Samples of digest from a further ten pancreata were similarly treated, comparing storage in MEM, UW, and five solutions varying in lactobionate:chloride ratio and raffinose content. The purity of the islet preparations and the densities of islets and exocrine tissue were determined from insulin and amylase assay of aliquots aspirated from these gradients. Washing and storage of digest in UW markedly improved islet purity, compared with MEM, due to an increase in the density of exocrine tissue. Exocrine tissue density following storage was dependent upon the control of acinar cell volume, rather than exocrine enzyme discharge, and was determined primarily by the chloride:lactobionate ratio of the storage solution. Raffinose was of little additional benefit, while the beneficial effect of UW was greater than that due to its lactobionate and raffinose content alone. In conclusion, inadequate purification of islets results from exocrine tissue swelling. This swelling is reduced by storage of the pancreatic digest in UW solution, due primarily to the replacement of chloride by lactobionate in UW.