Resectability of bilobar liver tumours after simultaneous portal and hepatic vein embolization versus portal vein embolization alone: meta-analysis

BACKGROUND

Many patients with bi-lobar liver tumours are not eligible for liver resection due to an insufficient future liver remnant (FLR). To reduce the risk of posthepatectomy liver failure and the primary cause of death, regenerative procedures intent to increase the FLR before surgery. The aim of this systematic review is to provide an overview of the available literature and outcomes on the effectiveness of simultaneous portal and hepatic vein embolization (PVE/HVE) versus portal vein embolization (PVE) alone.

METHODS

A systematic literature search was conducted in PubMed, Web of Science, and Embase up to September 2022. The primary outcome was resectability and the secondary outcome was the FLR volume increase.

RESULTS

Eight studies comparing PVE/HVE with PVE and six retrospective PVE/HVE case series were included. Pooled resectability within the comparative studies was 75 per cent in the PVE group (n = 252) versus 87 per cent in the PVE/HVE group (n = 166, OR 1.92 (95% c.i., 1.13-3.25)) favouring PVE/HVE (P = 0.015). After PVE, FLR hypertrophy between 12 per cent and 48 per cent (after a median of 21-30 days) was observed, whereas growth between 36 per cent and 67 per cent was reported after PVE/HVE (after a median of 17-31 days). In the comparative studies, 90-day primary cause of death was similar between groups (2.5 per cent after PVE versus 2.2 per cent after PVE/HVE), but a higher 90-day primary cause of death was reported in single-arm PVE/HVE cohort studies (6.9 per cent, 12 of 175 patients).

CONCLUSION

Based on moderate/weak evidence, PVE/HVE seems to increase resectability of bi-lobar liver tumours with a comparable safety profile. Additionally, PVE/HVE resulted in faster and more pronounced hypertrophy compared with PVE alone.

Dragon 1 Protocol Manuscript: Training, Accreditation, Implementation and Safety Evaluation of Portal and Hepatic Vein Embolization (PVE/HVE) to Accelerate Future Liver Remnant (FLR) Hypertrophy

STUDY PURPOSE

The DRAGON 1 trial aims to assess training, implementation, safety and feasibility of combined portal- and hepatic-vein embolization (PVE/HVE) to accelerate future liver remnant (FLR) hypertrophy in patients with borderline resectable colorectal cancer liver metastases.

METHODS

The DRAGON 1 trial is a worldwide multicenter prospective single arm trial. The primary endpoint is a composite of the safety of PVE/HVE, 90-day mortality, and one year accrual monitoring of each participating center. Secondary endpoints include: feasibility of resection, the used PVE and HVE techniques, FLR-hypertrophy, liver function (subset of centers), overall survival, and disease-free survival. All complications after the PVE/HVE procedure are documented. Liver volumes will be measured at week 1 and if applicable at week 3 and 6 after PVE/HVE and follow-up visits will be held at 1, 3, 6, and 12 months after the resection.

RESULTS

Not applicable.

CONCLUSION

DRAGON 1 is a prospective trial to assess the safety and feasibility of PVE/HVE. Participating study centers will be trained, and procedures standardized using Work Instructions (WI) to prepare for the DRAGON 2 randomized controlled trial. Outcomes should reveal the accrual potential of centers, safety profile of combined PVE/HVE and the effect of FLR-hypertrophy induction by PVE/HVE in patients with CRLM and a small FLR.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT04272931 (February 17, 2020). Toestingonline.nl: NL71535.068.19 (September 20, 2019).

Reinforced versus standard stapler transection on postoperative pancreatic fistula in distal pancreatectomy: multicentre randomized clinical trial

BACKGROUND

Postoperative pancreatic fistula is the leading cause of morbidity after distal pancreatectomy. Strategies investigated to reduce the incidence have been disappointing. Recent data showed a reduction in postoperative pancreatic fistula with the use of synthetic mesh reinforcement of the staple line.

METHODS

An RCT was conducted between May 2014 and February 2016 at four tertiary referral centres in Sweden. Patients scheduled for distal pancreatectomy were eligible. Enrolled patients were randomized during surgery to stapler transection with biological reinforcement or standard stapler transection. Patients were blinded to the allocation. The primary endpoint was the development of any postoperative pancreatic fistula. Secondary endpoints included morbidity, mortality, and duration of hospital stay.

RESULTS

Some 107 patients were randomized and 106 included in an intention-to-treat analysis (56 in reinforced stapling group, 50 in standard stapling group). No difference was demonstrated in terms of clinically relevant fistulas (grade B and C): 6 of 56 (11 per cent) with reinforced stapling versus 8 of 50 (16 per cent) with standard stapling (P = 0.332). There was no difference between groups in overall postoperative complications: 45 (80 per cent) and 39 (78 per cent) in reinforced and standard stapling groups respectively (P = 0.765). Duration of hospital stay was comparable: median 8 (range 2-35) and 9 (2-114) days respectively (P = 0.541).

CONCLUSION

Biodegradable stapler reinforcement at the transection line of the pancreas did not reduce postoperative pancreatic fistula compared with regular stapler transection in distal pancreatectomy. Registration number: NCT02149446 (http://www.clinicaltrials.gov).

Liver resection and ablation for squamous cell carcinoma liver metastases

Background

Limited evidence exists to guide the management of patients with liver metastases from squamous cell carcinoma (SCC). The aim of this retrospective multicentre cohort study was to describe patterns of disease recurrence after liver resection/ablation for SCC liver metastases and factors associated with recurrence-free survival (RFS) and overall survival (OS).

Method

Members of the European–African Hepato-Pancreato-Biliary Association were invited to include all consecutive patients undergoing liver resection/ablation for SCC liver metastases between 2002 and 2019. Patient, tumour and perioperative characteristics were analysed with regard to RFS and OS.

Results

Among the 102 patients included from 24 European centres, 56 patients had anal cancer, and 46 patients had SCC from other origin. RFS in patients with anal cancer and non-anal cancer was 16 and 9 months, respectively (P = 0.134). A positive resection margin significantly influenced RFS for both anal cancer and non-anal cancer liver metastases (hazard ratio 6.82, 95 per cent c.i. 2.40 to 19.35, for the entire cohort). Median survival duration and 5-year OS rate among patients with anal cancer and non-anal cancer were 50 months and 45 per cent and 21 months and 25 per cent, respectively. For the entire cohort, only non-radical resection was associated with worse overall survival (hazard ratio 3.21, 95 per cent c.i. 1.24 to 8.30).

Conclusion

Liver resection/ablation of liver metastases from SCC can result in long-term survival. Survival was superior in treated patients with liver metastases from anal versus non-anal cancer. A negative resection margin is paramount for acceptable outcome.

Preoperative portal vein or portal and hepatic vein embolization: DRAGON collaborative group analysis

BACKGROUND

The extent of liver resection for tumours is limited by the expected functional reserve of the future liver remnant (FRL), so hypertrophy may be induced by portal vein embolization (PVE), taking 6 weeks or longer for growth. This study assessed the hypothesis that simultaneous embolization of portal and hepatic veins (PVE/HVE) accelerates hypertrophy and improves resectability.

METHODS

All centres of the international DRAGON trials study collaborative were asked to provide data on patients who had PVE/HVE or PVE on 2016-2019 (more than 5 PVE/HVE procedures was a requirement). Liver volumetry was performed using OsiriX MD software. Multivariable analysis was performed for the endpoints of resectability rate, FLR hypertrophy and major complications using receiver operating characteristic (ROC) statistics, regression, and Kaplan-Meier analysis.

RESULTS

In total, 39 patients had undergone PVE/HVE and 160 had PVE alone. The PVE/HVE group had better hypertrophy than the PVE group (59 versus 48 per cent respectively; P = 0.020) and resectability (90 versus 68 per cent; P = 0.007). Major complications (26 versus 34 per cent; P = 0.550) and 90-day mortality (3 versus 16 per cent respectively, P = 0.065) were comparable. Multivariable analysis confirmed that these effects were independent of confounders.

CONCLUSION

PVE/HVE achieved better FLR hypertrophy and resectability than PVE in this collaborative experience.

Laparoscopic versus open extended radical left pancreatectomy for pancreatic ductal adenocarcinoma: an international propensity-score matched study

BACKGROUND

A radical left pancreatectomy in patients with pancreatic ductal adenocarcinoma (PDAC) may require extended, multivisceral resections. The role of a laparoscopic approach in extended radical left pancreatectomy (ERLP) is unclear since comparative studies are lacking. The aim of this study was to compare outcomes after laparoscopic vs open ERLP in patients with PDAC.

METHODS

An international multicenter propensity-score matched study including patients who underwent either laparoscopic or open ERLP (L-ERLP; O-ERLP) for PDAC was performed (2007-2015). The ISGPS definition for extended resection was used. Primary outcomes were overall survival, margin negative rate (R0), and lymph node retrieval.

RESULTS

Between 2007 and 2015, 320 patients underwent ERLP in 34 centers from 12 countries (65 L-ERLP vs. 255 O-ERLP). After propensity-score matching, 44 L-ERLP could be matched to 44 O-ERLP. In the matched cohort, the conversion rate in L-ERLP group was 35%. The L-ERLP R0 resection rate (matched cohort) was comparable to O-ERLP (67% vs 48%; P = 0.063) but the lymph node yield was lower for L-ERLP than O-ERLP (median 11 vs 19, P = 0.023). L-ERLP was associated with less delayed gastric emptying (0% vs 16%, P = 0.006) and shorter hospital stay (median 9 vs 13 days, P = 0.005), as compared to O-ERLP. Outcomes were comparable for additional organ resections, vascular resections (besides splenic vessels), Clavien-Dindo grade ≥ III complications, or 90-day mortality (2% vs 2%, P = 0.973). The median overall survival was comparable between both groups (19 vs 20 months, P = 0.571). Conversion did not worsen outcomes in L-ERLP.

CONCLUSION

The laparoscopic approach may be used safely in selected patients requiring ERLP for PDAC, since morbidity, mortality, and overall survival seem comparable, as compared to O-ERLP. L-ERLP is associated with a high conversion rate and reduced lymph node yield but also with less delayed gastric emptying and a shorter hospital stay, as compared to O-ERLP.

Comparison of the duration of hospital stay after laparoscopic or open distal pancreatectomy: randomized controlled trial

Background

Studies have suggested that laparoscopic distal pancreatectomy (LDP) is advantageous compared with open distal pancreatectomy (ODP) regarding hospital stay, blood loss and recovery. Only one randomized study is available, which showed enhanced functional recovery after LDP compared with ODP.

Methods

Consecutive patients evaluated at a multidisciplinary tumour board and planned for standard distal pancreatectomy were randomized prospectively to LDP or ODP in an unblinded, parallel-group, single-centre superiority trial. The primary outcome was postoperative hospital stay.

Results

Of 105 screened patients, 60 were randomized and 58 (24 women, 41 per cent) were included in the intention-to-treat analysis; there were 29 patients of mean age 68 years in the LDP group and 29 of mean age 63 years in the ODP group. The main indication was cystic pancreatic lesions, followed by neuroendocrine tumours. The median postoperative hospital stay was 5 (i.q.r. 4–5) days in the laparoscopic group versus 6 (5–7) days in the open group (P = 0·002). Functional recovery was attained after a median of 4 (i.q.r. 2–6) versus 6 (4–7) days respectively (P = 0·007), and duration of surgery was 120 min in both groups (P = 0·482). Blood loss was less with laparoscopic surgery: median 50 (i.q.r. 25–150) ml versus 100 (100–300) ml in the open group (P = 0·018). No difference was found in the complication rates (Clavien–Dindo grade III or above: 4 versus 8 patients respectively). The rate of delayed gastric emptying and clinically relevant postoperative pancreatic fistula did not differ between the groups.

Conclusion

LDP is associated with shorter hospital stay than ODP, with shorter time to functional recovery and less bleeding. Registration number: ISRCTN26912858 (www.isrctn.com).

Treatment patterns and survival in patients with hepatocellular carcinoma in the Swedish national registry SweLiv

BACKGROUND

Consistent data on clinical features, treatment modalities and long-term survival in patients with hepatocellular carcinoma (HCC) using nationwide quality registers are lacking. This study aimed to describe treatment patterns and survival outcomes in patients diagnosed with HCC using a national maintained database.

METHODS

Characteristics and treatment patterns in patients diagnosed with HCC and registered in the national register of liver and bile duct tumours (SweLiv) between 2009 and 2016 were reviewed. Overall survival (OS) was estimated using Kaplan-Meier analysis and the log rank test to compare subgroups for clinical features, treatment modalities and outcomes according to the year of treatment.

RESULTS

A total of 3376 patients with HCC were registered over 8 years, 246 (7·3 per cent) of whom underwent transplantation. Some 501 (14·8 per cent) and 390 patients (11·6 per cent) had resection and ablation as primary treatment. Transarterial chemoembolization and systemic sorafenib treatment were intended in 476 (14·1 per cent) and 426 patients (12·6 per cent) respectively; the remaining 1337 (39·6 per cent) were registered but referred for best supportive care (BSC). The 5-year survival rate was approximately 75 per cent in the transplantation group. Median OS was 4·6 (i.q.r. 2·0 to not reached) years after resection and 3·1 (2·3-6·7) years following ablation. In patients referred for palliative treatment, median survival was 1·4 (0·8-2·9), 0·5 (0·3-1·2) and 0·3 (0·1-1·0) years for the TACE, sorafenib and BSC groups respectively (P < 0·001). Median survival was 0·9 years for the total HCC cohort in 2009-2012, before publication of the Swedish national treatment programme, increasing to 1·4 years in 2013-2016 (P < 0·001).

CONCLUSION

The survival outcomes reported were in line with previous results from smaller cohorts. The introduction of national guidelines may have contributed to improved survival among patients with HCC in Sweden.

Characterization of early recurrences following liver resection by ALPPS and two stage hepatectomy in patients with colorectal liver-metastases and small future liver remnants; a translational substudy of the LIGRO-RCT

BACKGROUND

Associated liver partition and portal vein ligation in staged hepatectomy (ALPPS) is an alternative resection method to portal vein embolization (PVE) in patients with small future liver remnants (FLR) but has been associated with early tumor recurrences.

METHODS

Twenty-four patients with colorectal liver metastases (CRLM) patients from the randomized multicenter LIGRO trial comparing outcome of ALPPS (n = 13) vs PVE (n = 11) were included in the study. Mutational analyses of the KRAS, NRAS, BRAF, PIC3CA and TP53 genes of the metastases were performed in 21 patients and correlated to early tumor recurrence.

RESULTS

Within 12 months, 13 patients experienced recurrences (6 in TSH group and 7 in ALPPS group). Nine of 13 patients with recurrences had mutations in the TP53 gene, while 3 of 8 patients without recurrence carried the same mutation. Only sporadic cases of the other mutations studied were identified.

CONCLUSIONS

ALPPS did not appear to be associated with higher rate of rapid recurrences than PVE following radical resection of colorectal liver metastases. Mutations in genes associated with negative oncologic outcome after surgical resection most likely play a role for tumor recurrences in these patients.

Does the Introduction of Laparoscopic Distal Pancreatectomy Jeopardize Patient Safety and Well-Being?

Background/Purpose:

Despite retrospective data indicating short-term superiority for laparoscopic distal pancreatectomy compared to open distal pancreatectomy, the implementation of the procedure has been slow. The aim of this study was to investigate whether patients operated with laparoscopic distal pancreatectomy during the early phase of introduction are at higher risk for complications than patients operated with open distal pancreatectomy.

Methods:

A retrospective single-center analysis of patients operated with laparoscopic distal pancreatectomy (n = 37) from the introduction of the procedure and comparison regarding demographic data, preoperative data, operative factors, and postoperative outcomes to patients operated with open distal pancreatectomy was done.

Results:

Operation duration shortened (195 vs 143 min, p = 0.04) and severe complications reduced (37% vs 6%, p = 0.02) significantly in the laparoscopic distal pancreatectomy group between the first half of the study and the second half. Blood loss was significantly (p < 0.001) lower in the laparoscopic distal pancreatectomy group (75 mL) than in the open distal pancreatectomy group (550 mL), while complication rate and hospital stay as well as the percentage of radical resections were the same.

Conclusion:

Laparoscopic distal pancreatectomy can be introduced without jeopardizing patient safety and well-being during the early learning curve. The procedures should be compared in a prospective randomized manner.

Associating Liver Partition and Portal Vein Ligation for Primary Hepatobiliary Malignancies and Non-Colorectal Liver Metastases

Background and Aims:

Associating liver partition and portal vein ligation for staged hepatectomy may increase the possibility of radical resection in the case of liver malignancy. Concerns have been raised about the high morbidity and mortality associated with the procedure, particularly when applied for diagnoses other than colorectal liver metastases. The aim of this study was to analyze the initial experience with associating liver partition and portal vein ligation for staged hepatectomy in cases of non-colorectal liver metastases and primary hepatobiliary malignancies in Scandinavia.

Materials and Methods:

A retrospective analysis of all associating liver partition and portal vein ligation for staged hepatectomy procedures performed at two Swedish university hospitals for non-colorectal liver metastases and primary hepatobiliary malignancies was performed. The primary focus was on the safety of the procedure.

Results and Conclusion:

Ten patients were included: four had hepatocellular cancer, three had intrahepatic cholangiocarcinoma, one had a Klatskin tumor, one had ocular melanoma metastasis, and one had a metastasis from a Wilms’ tumor. All patients completed both operations, and the highest grade of complication (according to the Clavien-Dindo classification) was 3A, which was observed in one patient. No 90-day mortality was observed. Radical resection (R0) was achieved in nine patients, while the resection was R2 in one patient. The low morbidity and mortality observed in this cohort compared with those of earlier reports on associating liver partition and portal vein ligation for staged hepatectomy for diagnoses other than colorectal liver metastases may be related to the selection of patients with limited comorbidity. In addition, procedures other than associating liver partition and portal vein ligation for staged hepatectomy had been avoided in most of the patients. In conclusion, associating liver partition and portal vein ligation for staged hepatectomy can be applied to primary hepatobiliary malignancies and non-colorectal liver metastases with acceptable rates of morbidity and mortality.

Multivisceral Resection in Patients with Advanced Abdominal Tumors

BACKGROUND/AIM

Multivisceral resection for advanced tumors can result in prolonged survival but may also increase the risk of postoperative morbidity and mortality. The primary aim of this study was to investigate whether extensive resections increase the severity of postoperative complications.

MATERIALS AND METHODS

A retrospective study was conducted between 2009 and 2014 at the Linköping University Hospital surgical department. All patients with a confirmed or presumed malignant disease who underwent a non-standardized surgical procedure requiring a multivisceral resection were included. The primary endpoint was 90-day complications according to the Clavien-Dindo score.

RESULTS

Forty-eight patients were included, with an age range of 17-77 years. A median of three organs was resected. The most common diagnoses were neuroendocrine tumor (n = 8), gastric cancer (n = 7), and gastrointestinal stromal tumor (n = 6). One patient died during surgery. Complications ⩾ grade 3b according to Clavien-Dindo score occurred in 10 patients. R0 resection was achieved in 32 patients. No correlation was observed between the number of anastomoses, perioperative blood loss, operative time, and complications. Only postoperative blood transfusion was correlated with severe complications (p = 0.046); however, a tendency toward more complications with an increasing number of resected organs was observed (p = 0.06).

CONCLUSION

Multivisceral resection can result in R0, potentially curing patients with advanced tumors. Here, no correlation between extensive resections and complications was observed. Only postoperative blood transfusion was correlated with severe complications.

Associating liver partition and portal vein ligation for staged hepatectomy in patients with colorectal liver metastases--Intermediate oncological results

BACKGROUND

Colorectal liver metastases (CRLM) not amenable for resection have grave prognosis. One limiting factor for surgery is a small future liver remnant (FLR). Early data suggests that associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) effectively increases the volume of the FLR allowing for resection in a larger fraction of patients than conventional two-stage hepatectomy (TSH) with portal vein occlusion (PVO). Oncological results of the treatment are lacking. The aim of this study was to assess the intermediate oncological outcomes after ALPPS in patients with CRLM.

MATERIAL AND METHODS

Retrospective analysis of all patients with CRLM operated with ALPPS at the participating centres between December 2012 and May 2014.

RESULTS

Twenty-three patients (16 male, 7 female), age 67 years (28-80) were operated for 6.5 (1-38) metastases of which the largest was 40 mm (14-130). Six (27.3%) patients had extra-hepatic metastases, 16 (72.7%) synchronous presentation. All patients received chemotherapy, 6 cycles (3-25) preoperatively and 16 (70%) postoperatively. Ten patients (43%) were rescue ALPPS after failed PVO. Severe complications occurred in 13.6% and one (4.5%) patient died within 90 days of surgery. After a median follow-up of 22.5 months from surgery and 33.5 months from diagnosis of liver metastases estimated 2 year overall survival was 59% (from surgery) and 73% (from diagnosis). Liver only recurrences (n = 8), were treated with reresection/ablation (n = 7) while lung recurrences were treated with chemotherapy.

CONCLUSION

The overall survival, rate of severe complications and perioperative mortality associated with ALPPS for patients with CRLM is comparable to TSH.

Should ALPPS be Used for Liver Resection in Intermediate-Stage HCC?

BACKGROUND

Extended liver resections in patients with hepatocellular carcinoma (HCC) are problematic due to hepatitis, fibrosis, and cirrhosis. Associating liver partition with portal vein ligation for staged hepatectomy (ALPPS) has been promoted as a novel method to induce hypertrophy for patients with extensive colorectal liver metastases, but outcomes in HCC have not been well investigated.

METHODS

All patients registered in the international ALPPS Registry ( www.alpps.org ) from 2010 to 2015 were studied. Hypertrophy of the future liver remnant, perioperative morbidity and mortality, age, overall survival, and other parameters were compared between patients with HCC and patients with colorectal liver metastases (CRLM).

RESULTS

The study compared 35 patients with HCC and 225 patients with CRLM. The majority of patients undergoing ALPPS for HCC fall into the intermediate-stage category of the Barcelona clinic algorithm. In this study, hypertrophy was rapid and extensive for the HCC patients, albeit lower than for the CRLM patients (47 vs. 76 %; p < 0.002). Hypertrophy showed a linear negative correlation with the degrees of fibrosis. The 90-day mortality for ALPPS used to treat HCC was almost fivefold higher than for CRLM (31 vs. 7 %; p < 0.001). Multivariate analysis showed that patients older than 61 years had a significantly reduced overall survival (p < 0.004).

CONCLUSION

The ALPPS approach induces a considerable hypertrophic response in HCC patients and allows resection of intermediate-stage HCC, albeit at the cost of a 31 % perioperative mortality rate. The use of ALPPS for HCC remains prohibitive for most patients and should be performed only for a highly selected patient population younger than 60 years with low-grade fibrosis.

A Personal Computer Freeware as a Tool for Surgeons to Plan Liver Resections

BACKGROUND AND AIMS

The increase in liver surgery and the proportion of resections done on the margin to postoperative liver failure make preoperative calculations regarding liver volume important. Earlier studies have shown good correlation between calculations done with ImageJ and specimen weight as well as volume calculations done with more robust systems. The correlation to actual volumes of resected liver tissue has not been investigated, and this was the aim of this study.

MATERIAL AND METHODS

A total of 30 patients undergoing well-defined liver resections were included in this study. Volumes calculated with ImageJ were compared to volume measurements done after the retrieval of resected liver tissue.

RESULTS AND CONCLUSIONS

A strong correlation between calculated and measured liver volume was found with sample concordance correlation coefficient (ρc) = 0.9950. The knowledge on the nature of liver resections sets liver surgeons in a unique position to be able to accurately predict the volumes to be resected and, therefore, also the volume that will remain after surgery. This becomes increasingly important with the evolvement of methods to extend the boundaries of liver surgery. ImageJ is a reliable tool to preoperatively assess liver volume.

Seasonal changes in migratory and predatory activity of two species of gadoid preying on inshore northern shrimp Pandalus borealis

The interaction between two species of gadoid and a shrimp stock was studied in a 40 km long two-armed fjord in north-west Iceland. On the basis of acoustic and trawl surveys in 2005 and 2006, immature cod Gadus morhua and haddock Melanogrammus aeglefinus were found to migrate to the inner part of the fjord in late summer, concurrent with rising temperatures. At the same time, the local northern shrimp Pandalus borealis stock retreated into the north-east arm of the fjord. Vertical distribution of acoustic targets indicated that a significant and temporally variable fraction of the gadoids was inaccessible to the trawl. Shrimp was a significant part of the diet of immature G. morhua, except in June 2006 when euphausiids comprised most of the diet of both G. morhua and M. aeglefinus. Shrimp was only a minor part of the diet of M. aeglefinus. An on-off relationship was observed in the catches of gadoids and shrimp. In hauls with large catches of gadoids, few shrimp were found and vice versa, indicating avoidance reaction at this spatial scale. The cooling in winter may have driven the gadoids to the outer parts of the fjord, which in turn may have aided in the dispersal of the shrimp stock in the following months.

Immune parameters of immunised cod (Gadus morhua L.)

The immune response of cod (Gadus morhua L.) is unusual in that specific antibody response is limited or absent. In the present study cod was immunised with haptenated and non-haptenated protein antigen at two different temperatures and the antibody response monitored over a period of 18 months. Other humoral parameters of immunological importance were also analysed, namely total immunoglobulin concentration, anti-protease and spontaneous haemolytic activity. No specific antibody response was detected but increased activity of non-specific anti-TNP antibodies was observed 10-12 weeks after immunisation, irrespective of the antigen used. This antibody activity was attributed to the adjuvant used (FCA) and did not cross react with other antigens tested. Other parameters were probably not influenced by the immunisation but seasonal fluctuations were indicated. The immunoglobulin level appeared to peak in August-September and the anti-protease activity and the haemolytic activity in October-January.

Humoral immune parameters in Atlantic cod (Gadus morhua L.) I. The effects of environmental temperature

The effects of environmental temperature on certain humoral immune parameters in Atlantic cod (Gadus morhua L.) were studied. Serum samples were collected from captive cod, of wild origin, kept at different temperatures for 12 months. It was found that immunoglobulin and natural antibody levels increased with increasing temperature whereas the total serum protein concentration, anti-protease activity, iron concentration, unsaturated and total iron binding capacity decreased with increasing temperature. Haemolytic activity and percentage iron saturation also tended to decrease with increasing temperature although this was not statistically significant.

Humoral immune parameters in Atlantic cod (Gadus morhua L.) II. The effects of size and gender under different environmental conditions

The effects of size and gender on several humoral immune parameters in cod were examined under different environmental conditions. Serum samples were collected from wild cod of different sizes. Two samplings were undertaken: In the spring in relatively cold waters off the north west coast of Iceland and in the fall in relatively warm waters off the west coast of Iceland. Most of the parameters increased with increasing cod size, except the haemolytic activity which decreased. Higher serum protein levels were seen in cod sampled in the fall than in the spring. In cod sampled in the spring there was an apparent difference between specimens < 75 cm in length and the larger specimens with respect to haemolytic activity and iron concentration. None of the parameters were influenced by the gender of the cod.