Weak reproductive isolation and extensive gene flow between Mimulus glaucescens and M. guttatus in northern California

Barriers to reproduction are often how progress in speciation is measured. Nonetheless, an unresolved question concerns the extent to which reproductive barriers diminish gene flow between incipient species. The Sierra Nevada foothill endemic Mimulus glaucescens and the widespread M. guttatus are considered distinct species based on striking differences in vegetative morphology, but barriers to reproduction have not been previously identified, nor has gene flow between species been characterized. Here, we examined 15 potential reproductive barriers within a Northern California area of broad sympatry. Most barriers, with the exception of ecogeographic isolation, were weak or absent, and total isolation for each species was incomplete. Population genomic analyses of range-wide and broadly sympatric accessions revealed extensive gene flow between these taxa, particularly in sympatry. Despite widespread introgression, Mimulus glaucescens, emerged as monophyletic and largely comprised a single ancestry that was found at intermediate frequency within M. guttatus. This result, along with observed ecological and phenotypic differentiation, suggests that natural selection may contribute to the maintenance of distinct phenotypic forms in the earliest stages of speciation. Integrating estimates of barrier strength with direct estimates of gene flow can strengthen a more nuanced interpretation of the process of speciation in natural communities.

Has the non-resection rate decreased during the last two decades among patients undergoing surgical exploration for pancreatic adenocarcinoma?

Purpose

To determine if improvement in imaging reduces the non-resection rate (NRR) among patients with pancreatic ductal adenocarcinoma (PDAC).

Methods

From 2000 to 2019, 751 consecutive patients with PDAC were considered eligible for a intention-to-treat pancreatectomy and entered the operating room. In April 2011, our institution acquired a dual energy spectral computed tomography (CT) scanner and liver diffusion weighted magnetic resonance imaging (DW-MRI) was included in the imaging workup. We consequently considered 2 periods of inclusion: period #1 (February 2000–March 2011) and period #2 (April 2011–August 2019).

Results

All patients underwent a preoperative CT scan with a median delay to surgery of 18 days. Liver DW-MRI was performed among 407 patients (54%). Median delay between CT and surgery decreased (21 days to 16 days, P < .01), and liver DW-MRI was significantly most prescribed during period #2 (14% vs 75%, P < .01). According to the intraoperative findings, the overall NRR was 24.5%, and remained stable over the two periods (25% vs 24%, respectively). While vascular invasion, liver metastasis, and carcinomatosis rates remained stable, para-aortic lymph nodes invasion rate (0.4% vs 4.6%; P < 0.001) significantly increased over the 2 periods. The mean size of the bigger extra pancreatic tumor significantly decrease (7.9 mm vs 6.4 mm (P < .01), respectively) when the resection was not done. In multivariate analysis, CA 19–9 < 500 U/mL (P < .01), and liver DW-MRI prescription (P < .01) favoured the resection.

Conclusions

Due to changes in our therapeutic strategies, the NRR did not decrease during two decades despite imaging improvement.

Patient outcome according to the 2017 international consensus on the definition of borderline resectable pancreatic ductal adenocarcinoma

BACKGROUND/OBJECTIVE

We evaluated the usefulness of the 2017 definition of borderline pancreatic ductal adenocarcinoma (BR-PDAC) in fit patients (performance status 0-1) based on anatomical (A) and biological dimensions (B).

METHODS

From 2011 to 2018, 139 resected patients with BR-PDAC according to the 2017 definition were included: 18 patients underwent upfront pancreatectomy (CA 19-9 > 500 U/mL and/or regional lymph node metastasis; BR-B group), and 121 received FOLFIRINOX (FX) induction chemotherapy and were divided into BR-A (CA 19-9 < 500 U/mL, no regional lymph node metastasis; n = 68) and BR-AB (CA 19-9 > 500 U/mL and/or regional lymph node metastasis; n = 53) groups.

RESULTS

The 3 groups were comparable according to patient characteristics (except for back pain (P < .01) and CA 19-9 (P < .01)), intraoperative data, and postoperative courses. BR-AB patients required more venous resections (P < .01). The 3 groups were comparable on pathologic findings, except that BR-B patients had more lymph node invasions (P = .02). Median overall survival (OS) of the 121 patients was 45 months. In multivariate analysis, venous resection (P = .039) and R1 resection (P = .012) were poorly linked with OS, whereas BR-A classification (P < .01) independently favored OS. Median survival times of BR-A, BR-AB, and BR-B groups were undetermined, 27 months, and 20 months (P < .001), respectively.

CONCLUSIONS

The 2017 definition was relevant for sub-classifying patients with BR-PDAC. The anatomical dimension (BR-A) was a favorable prognostic factor, whereas the biological dimension (BR-AB and BR-B) poorly impacted survival.

Impact of cirrhosis in patients undergoing laparoscopic liver resection in a nationwide multicentre survey

BACKGROUND

The aim was to analyse the impact of cirrhosis on short-term outcomes after laparoscopic liver resection (LLR) in a multicentre national cohort study.

METHODS

This retrospective study included all patients undergoing LLR in 27 centres between 2000 and 2017. Cirrhosis was defined as F4 fibrosis on pathological examination. Short-term outcomes of patients with and without liver cirrhosis were compared after propensity score matching by centre volume, demographic and tumour characteristics, and extent of resection.

RESULTS

Among 3150 patients included, LLR was performed in 774 patients with (24·6 per cent) and 2376 (75·4 per cent) without cirrhosis. Severe complication and mortality rates in patients with cirrhosis were 10·6 and 2·6 per cent respectively. Posthepatectomy liver failure (PHLF) developed in 3·6 per cent of patients with cirrhosis and was the major cause of death (11 of 20 patients). After matching, patients with cirrhosis tended to have higher rates of severe complications (odds ratio (OR) 1·74, 95 per cent c.i. 0·92 to 3·41; P = 0·096) and PHLF (OR 7·13, 0·91 to 323·10; P = 0·068) than those without cirrhosis. They also had a higher risk of death (OR 5·13, 1·08 to 48·61; P = 0·039). Rates of cardiorespiratory complications (P = 0·338), bile leakage (P = 0·286) and reoperation (P = 0·352) were similar in the two groups. Patients with cirrhosis had a longer hospital stay than those without (11 versus 8 days; P = 0·018). Centre expertise was an independent protective factor against PHLF in patients with cirrhosis (OR 0·33, 0·14 to 0·76; P = 0·010).

CONCLUSION

Underlying cirrhosis remains an independent risk factor for impaired outcomes in patients undergoing LLR, even in expert centres.

'Peripheric' pancreatic cysts: performance of CT scan, MRI and endoscopy according to final pathological examination

OBJECTIVE

To assess the accuracy of pre-operative staging in patients with peripheral pancreatic cystic neoplasms (pPCNs).

METHODS

From 2005 to 2011, 148 patients underwent a pancreatectomy for pPCNs. The pre-operative examination methods of computed tomography (CT), magnetic resonance imaging (MRI), endoscopic ultrasonography (EUS) were compared for their ability to predict the suggested diagnosis accurately, and the definitive diagnosis was affirmed by pathological examination.

RESULTS

A mural nodule was detected in 34 patients (23%): only 1 patient (3%) had an invasive pPCN at the final histological examination. A biopsy was performed in 79 patients (53%) during EUS: in 55 patients (70%), the biopsy could not conclude a diagnosis; the biopsy provided the correct and wrong diagnosis in 19 patients (24%) and 5 patients (6%), respectively. A correct diagnosis was affirmed by CT, EUS and pancreatic MRI in 60 (41%), 103 (74%) and 80 (86%) patients (when comparing EUS and MRI; P = 0.03), respectively. The positive predictive values (PPVs) of CT, EUS and MRI were 70%, 75% and 87%, respectively.

CONCLUSIONS

Pancreatic MRI appears to be the most appropriate examination to diagnose pPCNs accurately. EUS alone had a poor PPV. Mural nodules in a PCN should not be considered an indisputable sign of pPCN invasiveness.

Two-stage hepatectomy: who will not jump over the second hurdle?

BACKGROUND

Two-stage hepatectomy uses compensatory liver regeneration after a first noncurative hepatectomy to enable a second curative resection in patients with bilobar colorectal liver metastasis (CLM).

OBJECTIVE

To determine the predictive factors of failure of two-stage hepatectomy.

METHOD

Between 2000 and 2010, 48 patients with irresectable CLM were eligible for two-stage hepatectomy. The planned strategy was a) cleaning of the left hepatic lobe (first hepatectomy), b) right portal vein embolisation and c) right hepatectomy (second hepatectomy). Six patients had occult CLM (n = 5) or extra-hepatic disease (n = 1), which was discovered during the first hepatectomy. Thus, 42 patients completed the first hepatectomy and underwent portal vein embolisation in order to receive the second hepatectomy. Eight patients did not undergo a second hepatectomy due to disease progression.

RESULTS

Upon univariate analysis, two factors were identified that precluded patients from having the second hepatectomy: the combined resection of a primary tumour during the first hepatectomy (p = 0.01) and administration of chemotherapy between the two hepatectomies (p = 0.03). An independent association with impairment to perform the two-stage strategy was demonstrated by multivariate analysis for only the combined resection of the primary colorectal cancer during the first hepatectomy (p = 0.04).

CONCLUSION

Due to the small number of patients and the absence of equivalent conclusions in other studies, we cannot recommend performance of an isolated colorectal resection prior to chemotherapy. However, resection of an asymptomatic primary tumour before chemotherapy should not be considered as an outdated procedure.

Immunohistochemical staining for mismatch repair proteins, and its relevance in the diagnosis of hereditary non-polyposis colorectal cancer

BACKGROUND

Hereditary non-polyposis colorectal cancer (HNPCC) arises mostly from germline mutations of the mismatch repair genes MSH2 and MLH1. The diagnosis of HNPCC is based on a set of clinical criteria that may be too restrictive to identify all affected patients. Immunohistochemical staining (IHC) for the mismatch repair proteins, MutS homologue 2 (MSH2) and MutL homologue 1 (MLH1), reliably identifies the microsatellite instability phenotype. This study evaluated the ability of IHC to detect germline mutations in an unselected group of patients with colorectal cancer (CRC).

METHODS

All patients with CRC operated on between July 2000 and March 2003, and demonstrating a loss of protein, were contacted. Following informed consent, searchs for germline mutation and methylation of the promoter were performed on normal and tumoral DNA.

RESULTS

Thirty patients agreed to participate, four of whom fulfilled the Amsterdam II criteria. Loss of expression of MLH1 was found in 20 patients, and loss of expression of MSH2 in ten patients. Four of the MLH1-deficient patients had a germline MLH1 point mutation (positive predictive value (PPV) 20 (95 per cent confidence interval (c.i.) 2 to 38 per cent) and 11 had promoter methylation. Seven of the MSH2-deficient patients had a germline MSH2 point mutation (PPV 70 (95 per cent c.i. 54 to 96 per cent), and none showed promoter methylation.

CONCLUSION

MLH1-deficient patients who are young or have a positive family history of cancer should be referred for genetic testing and counselling, whereas MSH2-deficient patients should be counselled in the same way as patients with HNPCC.

Extracorporeal Circulation as an Additional Method for Cerebral Protection in Simultaneous Carotid Endarterectomy and Coronary Artery Surgical Revascularization

Surgical management of patients with concomitant carotid and coronary artery stenosis remains controversial. Our policy was always to perform at the same time carotid endarterectomy (CE) and coronary artery bypass grafting (CABG), but it was also considered that extracorporeal circulation (ECC), because of full heparinization, hemodilution, pulsatile flow, and hypothermia could provide better cerebral protection during CE. Retrospective data of 124 patients undergoing simultaneous CE and CABGs between January 1994 and December 2001 were reviewed. CE was performed prior to ECC in 65 patients (Group 1-mean age: 70.4 years; sex ratio: 49 male/16 female) and under ECC, prior to CABGs in 59 patients (Group 2-mean age: 69.9 years; sex ratio: 46 male/13 female). Overall hospital mortality was 7.3% (9/124): cardiac-related in 5 patients, or due to septicemia (1 patient), or ARD syndrome (1 patient), or stroke in two others. Univariate analysis demonstrated overweight, unstable angina, and emergency to be significant risk factors. Bilateral carotid stenosis was a significant risk factor of neurologic event when CE was performed prior to ECC (p < 0.05). In Group 1, mortality was 9.2% (6/65), and the incidence of neurologic events was 10.7% (7/65), and was responsible for two of the early deaths in patients with bilateral carotid stenosis. In Group 2, mortality was 5.1% (3/59) but never related to CE, while the neurologic morbidity was 1.7% (1 transient ischemic attack). It is concluded that (1) hospital mortality in patients undergoing simultaneous CE and CABGs was mainly cardiac-related. (2) The combined approach of both localizations appears to be mandatory, when carotid stenosis, even asymptomatic, was hemodynamically significant, or with ulcerative lesions likely to be responsible for embolism. (3) CE, first performed under ECC, appears to be a safe procedure, combining, in terms of cerebral protection, the benefits previously called up. This approach is all the more interesting when carotid stenosis is bilateral; hypothermia < or = 28 degrees C during the carotid clamping time is obviously the optimal method for cerebral protection when ipsilateral or contralateral supply is reduced, or even absent.

An unusual case of refractory Campylobacter jejuni infection in a patient with X-linked agammaglobulinemia: successful combined therapy with maternal plasma and ciprofloxacin

An unusual hippurate-negative strain of Campylobacter jejuni caused a chronic refractory infection in a patient with X-linked agammaglobulinemia; this infection persisted for > 2 years despite therapy with various antibiotics and immunoglobulins (Igs). To characterize the defense status of this patient, several in vitro studies, including those with T cells and polymorphonuclear leukocytes (PMNLs), were performed. T cell responses specific for C. jejuni were only weak in this patient. Chemiluminescence and bacterial killing studies with PMNLs revealed that the bactericidal activity of PMNLs against Campylobacter was enhanced more vigorously by maternal serum than by commercial Ig preparations. On the basis of these results, combined treatment with ciprofloxacin and maternal plasma was initiated, and the C. jejuni infection was rapidly cured. This case report shows that in vitro immunologic assays may be useful for characterizing immune functions of patients with chronic or refractory C. jejuni infections, thus leading to individual treatment strategies.

Body composition during long-term treatment of uremia with amino acid supplemented low-protein diet

The influence on body composition of prolonged treatment with low-protein diet (20 g/day) supplemented with the essential amino acids and histidine was studied in 49 patients with chronic renal failure and uremic symptoms. Total body potassium (TBK) was measured with 40K in a whole-body counter. Total body water was determined with dilution of tritiated water. Predicted values for TBK and total body water were obtained from a reference population of 476 healthy subjects. In 38 patients investigated before treatment body weight was normal while mean TBK was 91% of predicted in men and 100% in women. Mean total body water was 104% of predicted in both men and women. Thirty-one patients were investigated at 3-month intervals during treatment for up to 12 months. No significant changes in mean body weight, TBK, or total body water were found. However, in 10/13 patients TBK decreased significantly, presumably due to increased catabolism in connection with intercurrent disease or insufficient energy intake. In the absence of complications long-term treatment with a low-protein diet and essential amino acids in renal failure seems to maintain body cell mass reflected in unchanged TBK.

Plasma lipids and lipoproteins in young patients with brain infarction

Thirty-two patients aged 60 or less with brain infarction were examined with regard to possible changes in lipoprotein pattern as compared with a reference group. Except for a lower concentration of total lipids, cholesterol and high-density lipoproteins in the female patients, no difference was demonstrated in the two groups. In all patients a significant reduction in total lipids, cholesterol, triglyceride and all lipoproteins was demonstrated after the acute cerebrovascular accident presumedly due to the stress situation.

Renal function studies after donor nephrectomy

The remaining kidney undergoes compensatory hypertrophy after donor nephrectomy. Studies have shown that immediate increases of renal plasma flow (RPF) and glomerular filtration rate (GFR) take place. No studies of tubular functions in kidney donors have previously been published. Nine elderly kidney donors with a mean age of 55 years (range 48-71 years) underwent the following studies before and 6 and 12 months after nephrectomy: GFR, RPF, maximal tubular secretion of para-aminohippurate (TmPAH), net acid excretion after 3 days of ammonium chloride loading and test of the urinary concentration ability. RPFP and GFR decreased postoperatively to a mean of 61 and 63.5 per cent respectively, with a rise of the filtration fraction (FF). TmPAH decreased considerably less, to 76 per cent 6 months postoperatively and 86 per cent 12 months postoperatively. The TmPAH/GFR ratio changed from 0.77 to 0.95 and 0.99 postoperatively. The excretion of acid was slightly reduced concerning the NH4+-excretion but the values for H+-excretion and urinary pH were unchanged. The remaining kidney after donor nephrectomy shows the well-known increases in RPF and GFR. Energy-dependent proximal tubular functions such as TmPAH increase even more, indicating an altered glomerulotubular balance. Distal tubular function such as acidification and urinary concentration ability are essentially unchanged.