Identification of long-preserved specimens reveals the historical geographic range of the Patagonian lamprey Geotria macrostoma (Burmeister, 1868) in southern South America.

The lamprey genus Geotria Gray, 1851 currently includes only two species: G. australis and G. macrostoma. However, taxonomic relationships within the genus have traditionally been ambiguous and difficult to establish due to the extreme changes in morphology, dentition, and coloration that lampreys undergo during their life cycles, particularly during upstream migration and sexual maturation. Consequently, several lamprey specimens held in museum collections have remained unidentified, especially those from Argentina. In this study, a series of morphometric characters were subjected to discriminant function analysis (DFA) to identify the lamprey species collected during 1867-2004 from the de la Plata River and Patagonia. These specimens are housed at the Museo Argentino de Ciencias Naturales "Bernardino Rivadavia" in Buenos Aires, the Museo de Historia Natural de Montevideo, and the Naturhistoriska riksmuseet in Stockholm. Based on the proportions of the length of the oral disc, prebranchial, and pre-caudal body regions, and the depth of the trunk, DFA provided conclusive evidence that the specimens corresponded to the recently revalidated G. macrostoma (Burmeister, 1868), which was originally incorrectly named as Petromyzon macrostomus Burmeister, 1868, Exomegas macrostomus (Berg, 1899), Geotria chilensis (Berg, 1895), and Geotria macrostoma f. gallegensis Smitt, 1901, as well as other nontype museum individuals of uncertain taxonomic status. The identifications of these long-preserved museum specimens provided key information on the historical geographic range of Argentinian lampreys and suggest that the disappearance of the species reported from northern localities (the Pampean Region) can be attributed to the degradation of their critical habitats, primarily caused by anthropogenic impact and climate change.

Clinical experience with intraperitoneal sodium thiosulphate for calciphylaxis in peritoneal dialysis: A case series.

Calciphylaxis is an uncommon but life-threatening syndrome in end-stage kidney disease, characterised by painful medial and intimal calcification of the arterioles in the deep dermis and subcutaneous tissues. Intravenous sodium thiosulfate serves as an off-label but effective treatment in haemodialysis patients. However, this approach confers considerable logistical challenges for affected peritoneal dialysis patients. In this case series, we demonstrate that intraperitoneal administration can be a safe, convenient and long-term alternative.

A real-world study on SGLT2 inhibitors and diabetic kidney disease progression.

Background: Randomized controlled trials have demonstrated the benefits of sodium-glucose cotransporter 2 inhibitors (SGLT2is) in people with type 2 diabetes mellitus (T2DM) and chronic kidney disease (CKD). However, real-world data on CKD progression and the development of end-stage kidney disease (ESKD) remains scarce. Our aim was to study renal outcomes of people with diabetic kidney disease (DKD) using SGLT2is in a highly prevalent DKD population. Methods: Between 2016 and 2019 we recruited T2DM patients in the renal and diabetic clinics in a regional hospital in Singapore. Patients prescribed SGLT2is were compared with those on standard anti-diabetic and renoprotective treatment. The outcome measures were CKD progression [a ≥25% decrease from baseline and worsening of estimated glomerular filtration rate (eGFR) categories according to the Kidney Disease: Improving Global Outcomes guidelines] and ESKD (eGFR <15 mL/min/1.73 m2). Results: We analysed a total of 4446 subjects; 1598 were on SGLT2is. There was a significant reduction in CKD progression {hazard ratio [HR] 0.60 [95% confidence interval (CI) 0.49-0.74]} with SGLT2is. The HR for eGFR ≥45 mL/min/1.73 m2 and 15-44 mL/min/1.73 m2 was 0.60 (95% CI 0.47-0.76) and 0.43 (95% CI 0.23-0.66), respectively. There was also a reduction in risk for developing ESKD for the entire cohort [HR 0.33 (95% CI 0.17-0.65)] and eGFR 15-44 mL/min/1.73 m2 [HR 0.24 (95% CI 0.09-0.66)]. Compared with canagliflozin and dapagliflozin, empagliflozin showed a sustained risk reduction of renal outcomes across CKD stages 1-4. Conclusions: This real-world study demonstrates the benefits of SGLT2is on CKD progression and ESKD. The effect is more pronounced in moderate to advanced CKD patients.

On the invalid resurrection of the lamprey genus Exomegas Gill, 1883.

The lamprey genus Exomegas Gill, 1883, was erected on the assumption that it was distinguishable from Geotria Gray, 1851, by possessing three rather than two cusps on the transverse lingual lamina (TLL). Based on literature review and examination of holotypes and new data, the authors reaffirm that the TLL of Geotria possesses two or three cusps in the adult stage. The reduction or disappearance of the middle cusp at the beginning or during the spawning run constitutes a key feature of Geotria. The resurrection of Exomegas by Firpo Lacoste, Fernández and Scioscia, Journal of Fish Biology, 2021, 1-6, 1507-1512, is therefore unjustified and not supported.

Morphometric and physical characteristics distinguishing adult Patagonian lamprey, Geotria macrostoma from the pouched lamprey, Geotria australis.

The pouched lamprey, Geotria australis Gray, 1851, has long been considered monotypic in the Geotriidae family with a wide southern temperate distribution across Australasia and South America. Recent studies have provided molecular and morphological evidence for a second Geotria species in South America; Geotria macrostoma (Burmeister, 1868). The aim of this study was to determine morphometric and physical characteristics of adult G. macrostoma that further differentiate this re-instated species of Geotriidae from G. australis. The diagnostic features discriminating immature adult G. macrostoma from G. australis when entering fresh water, are distinct differences in dentition, oral papillae and fimbriae counts and differences in coloration. In addition, G. macrostoma display greater growth of the prebranchial region and oral disc and has a deeper body depth and higher condition factor. All current ecological knowledge of the genus Geotria is based on Australasian populations, which may not be applicable to G. macrostoma. To ensure the conservation and protection of the Patagonian lamprey as a re-identified species, further investigations are needed to understand its life history, biology and ecology throughout its range.

Morphology-based taxonomic re-assessment of the Arctic lamprey, Lethenteron camtschaticum (Tilesius, 1811) and taxonomic position of other members of the genus.

The lamprey genus Lethenteron Creaser & Hubbs, 1922 is widespread across Eurasia and North America, but the number and distribution of its constituent species is not firmly established. After a morphological examination of extant type material of the currently recognized species and their synonyms, Lethenteron mitsukurii (Hatta, 1901) is resurrected with Le. matsubarai Vladykov & Kott, 1978 as its junior synonym. Amongst nonparasitic species Le. reissneri (Dybowski, 1869) and Le. mitsukurii are confirmed as present in Japan and the former is also present on Sakhalin. An in-depth study of large samples of nonparasitic lamprey adults from Japan and Sakhalin Island is needed to determine whether the lower trunk myomere (< 66) individuals from these areas represent one or more undescribed species, or Le. mitsukurii, or Le. reissneri, or a mixture of these three alternatives. The material from the Anadyr Estuary identified by Berg (1931, 1948) as Lampetra japonica kessleri has been re-identified as Le. camtschaticum and there is no evidence that Le. kessleri occurs there. Lethenteron reissneri is reported from the Angara River system, Yenisei River drainage, Russia. Lethenteron alaskense Vladykov & Kott, 1978 is provisionally considered to be a junior synonym of Le. kessleri (Anikin, 1905). Petromyzon ernstii Dybowski, 1872, Ammocoetes aureus Bean, 1881, Petromyzon dentex Anikin, 1905, Lampetra mitsukurii major Hatta, 1911, and Lampetra japonica septentrionalis Berg, 1931 are junior synonyms of Petromyzon marinus camtschaticus Tilesius, 1811. A key is provided to adults of the six species recognized as belonging in the genus Lethenteron.

Faculty Use of Active Learning in Postgraduate Nephrology Education: A Mixed-Methods Study.

BACKGROUND: Active learning is an effective instructional tool in medical education. However, its integration by nephrology faculty remains limited despite residents' declining interest in nephrology. STUDY DESIGN: A sequential explanatory mixed-methods study design was used to explore nephrology faculty understanding of difficult teaching topics and active learning integration using the theory of planned behavior as theoretical framework. SETTING & PARTICIPANTS: Nephrology faculty at 6 residency sites in Singapore were recruited. METHODOLOGY: A 28-item questionnaire was administered to conveniently sampled faculty followed by 1-to-1 semi-structured interviews of a purposively sampled subset. ANALYTICAL APPROACH: Quantitative data were analyzed using descriptive and regression statistics. Qualitative data were analyzed using thematic analysis in line with the theory of planned behavior constructs (attitude, subjective norm, perceived behavioral control, intention, and behavior). RESULTS: 49 of 82 invited faculty responded, with 49% and 42% perceiving self-directed learning and interactive lectures, respectively, as active learning formats. Fluid, electrolyte, and acid-base disturbances; transplantation immunology; glomerulonephritis; and hemodialysis adequacy were cited as difficult topics by 75%, 63%, 45%, and 31% of responders, respectively. Only 55% reported integrating active learning formats when teaching difficult topics. Faculty in leadership roles and teaching difficult topics more regularly were more likely to adopt active learning formats. Multivariable logistic regression analysis showed that faculty attitude strongly and significantly predicted active learning intention. Thematic analysis identified 4 themes: active learning competence, barriers and challenges, environmental influence, and self-identity. Self-identity, defined as values developed from past behavior and experience, emerged as an important contributor to active learning adoption outside the theory of planned behavior framework. LIMITATIONS: Sampling, context, and measurement biases may affect study reliability and generalizability. CONCLUSIONS: Nephrology faculty lack active learning competence and face cognitive challenges when teaching difficult topics. Faculty teaching experience significantly influenced active learning adoption. Our findings build on the theoretical understanding of faculty instructional innovation adoption and can inform nephrology faculty development initiatives.

Outcomes of a nephrologist-driven tunnelled dialysis catheter insertion service in South East Asia.

INTRODUCTION: Tunnelled dialysis catheters (TDCs) are being increasingly inserted by nephrologists globally but there is limited experience and paucity of published outcomes data from South-East Asia (SEA). This study was conducted to analyse the outcomes of TDC insertion by nephrologists from a single centre in SEA. METHODS: All patients who underwent TDC insertion by nephrologists from October 2013 to June 2016 were included. TDC survival was calculated using Kaplan-Meier survival method. Impact of variables was assessed using Cox proportional hazards model. RESULTS: A total of 344 TDCs were inserted in 274 patients. The most common indication was haemodialysis initiation (60.2%) followed by existing catheter dysfunction (CD) (12.2%), failed vascular access (10.2%) and catheter-related bacteraemia (CRB) (9.9%). Insertion was successful in 97% patients. The most common location was the right internal jugular vein (87%). The cumulative survival for all TDCs inserted, as defined by the time to non-elective removal of a TDC, at 3, 6 and 9 months was 83%, 61%, and 44%, respectively. Median catheter survival was 231 days. Common indications for removal were CD (13.4%) and CRB or suspected infection (12.5%). Common complications were bleeding (8.72%), infection (13.7%) and CD (16.5%). Median time to infection was 103 days. In multivariate analysis, male gender was associated with poor catheter survival, for primary insertions (p = 0.015, HR 0.62) and diabetes was associated with TDC infection (p = 0.024, OR 1.1). CONCLUSIONS: This is one of the first reports of TDC insertion by nephrologists from SEA. Our outcomes compare favourably with those reported in the literature.

Post-hemodialysis dosing of 1 vs. 2 g of ceftazidime in anuric end-stage renal disease patients on low-flux dialysis and its pharmacodynamic implications on clinical use.

Ceftazidime is a cost-effective antimicrobial against Gram-negative pathogens associated with sepsis in end-stage renal disease (ESRD) hemodialysis patients with potential for wider use with the advent of ceftazidime-avibactam. Dosing ceftazidime post-hemodialysis appears attractive and convenient, but limited in vivo data on pharmacodynamic efficacy (PE) attainment, defined as >70% of the interdialytic period drug concentrations exceed susceptible pathogens minimal inhibitory concentrations (MICs) (%TMIC), warrants further assessment. We therefore evaluated PE and tolerability of 1 against 2 g regime in anuric ESRD patients on low-flux hemodialysis. Two doses of 1 or 2 g ceftazidime were administered post-hemodialysis prior to 48- and 72-hour interdialytic intervals in ESRD inpatients without active infections. Peak and trough concentrations (mg/L) were assayed using a validated liquid chromatography-tandem mass spectrometry method. Proportion of patients achieving PE for known pathogens with MICs ≤ 8 mg/L and adverse effects were assessed. Six (43%) and eight (57%) adult patients received 1 and 2 g dose, respectively. Median (25th-75th percentile), peak, 48- and 72-hour trough ceftazidime concentrations were 78 (60-98) vs. 158 (128-196), 37 (23-37) vs. 49 (39-71), and 13 (12-20) vs. 26 (21-41) mg/L, respectively, resulting in 100% TMIC for both doses. One patient on the 1-g dose experienced mild pruritus. Reliable and safe PE attainment over both 48- and 72-hour interdialytic interval was achievable with 1 g of ceftazidime dosed post-hemodialysis. The 2 g dose was equally effective and well tolerated but may not be necessary. These findings need validation in non-anuric patients, high-flux hemodialysis, and during avibactam co-administration.

Effect of brachial plexus block-driven vascular access planning on primary distal arteriovenous fistula recruitment and outcomes.

OBJECTIVE: Hemodialysis vascular accesses (VAs) are traditionally planned based on the nondominant upper extremity preoperative physical and sonographic vascular findings. Clinical guidelines advocate the use of the most suitably distended vein in the most distal location. Brachial plexus block (BPB), through its sympathectomy-like effect, promotes vasodilation and can thus further optimize vein recruitment and operative strategy. However, studies on its role in driving primary distal autogenous arteriovenous fistula (AVF) placement are limited. We therefore evaluated a traditional approach of clinic-based VA planning against an on-table sonography-guided strategy under BPB. METHODS: This was a prospective observational study involving 110 consecutive end-stage renal disease multiethnic Asian patients referred for primary VA creation under BPB after preoperative venous mapping. Cases were grouped according to whether there was a preset operative plan for radial cephalic (RC) or brachial cephalic (BC) AVF creation based on artery and vein >2 mm and >2.5 mm size criteria respectively (group A) or vein size or length were suboptimal (2-2.5 mm and <5 cm respectively), thus precluding any operative plan till after BPB (group B). Group B also included cases with a preset VA plan but that subsequently underwent an on-table change in operative plan as a result of more favorable distal vein dilation post-BPB. RC AVF recruitment, maturation, and patency rates were compared in the two groups over a 1-year follow up. RESULTS: One hundred RC and BC AVF were available for analysis after excluding brachial AVFs and grafts: 41 in group A and 59 in group B. Twenty one (51%) primary RC AVFs were created according to a preset preoperative plan compared with 37 (63%) based upon on-table planning or plan modification (P > .05). Satisfactory post-BPB forearm vasodilation resulted in 44% of 36 plans for BC being changed to RC AVFs. RC AVF 6-week hemodynamic maturation and 3-month functional maturation in group A vs B were 48% vs 60% and 69% vs 57%, respectively (P > .05). One-year primary and secondary patency rates were 57% vs 50% and 73% vs 87%, respectively (log rank >.05). Outcomes of RC AVFs in group B were not inferior to those of BC AVFs. CONCLUSIONS: On-table BPB-driven VA planning and plan modification strategy contribute to considerable AVF recruitment but do not lead to significantly better distal AVF prevalence or outcomes over the traditional approach. An adequately powered randomized controlled study is, however, warranted to better assess the long-term clinical and cost benefits of such a strategy.

Redescription of the Far Eastern brook lamprey Lethenteronreissneri (Dybowski, 1869) (Petromyzontidae).

Nonparasitic Lethenteronreissneri (Dybowski) is redescribed based on four syntypes (two adults and two ammocoetes) from the Onon and Ingoda rivers, Russia, and 15 topotypic specimens (seven metamorphosing ammocoetes and eight ammocoetes) from the Onon River system, Russia and Mongolia. Posterial teeth were not mentioned in the original description, but Berg (1931) stated that they were sometimes absent, which he later (Berg 1948) changed to usually absent, based on material (some of which we have re-identified as parasitic Lethenteroncamtschaticum) from far outside of the type locality. The latter view has been widely accepted by subsequent authors. Unfortunately, the poor condition of the two adult syntypes did not permit verification of this character. However, a row of posterials was clearly visible in six of the seven topotypic metamorphosing ammocoetes and indicates their usual presence in the species. The first full description of the ammocoetes, including pigmentation, is provided. The present study restricts the distribution of Lethenteronreissneri to the Shilka and Songhua river systems within the Amur River basin, until a more geographically comprehensive study is undertaken. Additionally, in this study, feeding versus non-feeding at the adult stage, are considered to be valid taxonomic characters at the species level.

Transjugular tunnelled dialysis catheter tip placement into the inferior vena cava upper segment after length overestimation.

PURPOSE: The right atrium is preferred over the superior vena cava (SVC) for tunnelled dialysis catheter (TDC) tip placement as it offers the best compromise between optimal catheter performance and complications. However, clinical practice guidelines are not all unanimous on this as a universal recommendation. Right atrial tip placement may also fail due to variations in body surface area, venous anatomy or TDC designs and lengths. Moreover, the presence of recurrent long intra-cardiac fibrin sheath or cardiac rhythm management device leads serves as contraindications. Extra-cardiac tip placement in the azygous, hepatic veins and lower segment of the inferior vena cava (IVC) is an alternative but is invariably associated with poor blood flow and shortened patency. METHODS: We report the concept of extra-cardiac tip placement into the larger calibre hepatic segment IVC via a transjugular approach in two diabetic haemodialysis patients with overestimated TDC length out of 380 insertions. RESULTS: Blood flow was maintained above 250 ml/min for 5-6 months and no tip migration ensued. CONCLUSIONS: The IVC upper segment is a reliable site for extra-cardiac tip placement in select cases but its safety and efficacy need to be further studied in larger clinical trials.

Effect of ultra-low dose and standard heparin locks on early tunnelled dialysis catheter outcomes in low-risk dialysis patients.

AIM: Initial heparin locks instilled after tunnelled dialysis catheter (TDC) insertion can leak causing systemic anticoagulation and also promote staphyloccocal biofilm formation, predisposing to catheter-related infection (CRI). The 1000 U/mL concentration is thus advocated as the optimal dose for preventing catheter bleeding and malfunction. The effect of lower heparin concentrations on further lowering these complications is not known. We compared early TDC outcomes between a non-standard ultra-low (500 U/mL) and standard initial heparin locks (1000 and 5000 U/mL). METHODS: This was a retrospective study on prospectively collected data on 238 de novo internal jugular TDCs placed by nephrologists. Cases were categorized into groups 1, 2 and 3, according to initial heparin lock: 500 [n = 30], 1000 [n = 180] and 5000 U/mL [n = 28] respectively. Bleeding and malfunction within 24 h of TDC insertion, 30 days CRI-free catheter survival and the effects of clinical and laboratory factors on bleeding were evaluated. RESULTS: Bleeding events were similar in groups 1, 2 and 3 (7 vs 14 vs 13%, respectively, P = 0.61). Malfunction was only seen in group 2 (3.3%). Thirty-day CRI-free catheter survival was comparable (96 vs 98 vs 97%, respectively, P = 0.22), giving a cumulative CRI rate of 0.76/1000 catheter days. All CRIs were staphylococcal. Univariate analysis did not reveal any significant predictors of catheter bleeding. CONCLUSION: Immediate TDC bleeding, malfunction and CRI rate are not influenced by heparin lock concentrations ≤5000 U/mL in this low-risk cohort. However this needs to be corroborated in higher risk patients.

Comparative outcomes of primary autogenous fistulas in elderly, multiethnic Asian hemodialysis patients.

BACKGROUND: The number of elderly (≥65 years) end-stage renal disease (ESRD) patients on hemodialysis is rapidly increasing. Vascular access outcomes remain contradictory and understudied across different elderly populations. We hypothesized age might influence primary autogenous fistula use and outcomes in a predominantly diabetic multiethnic Asian ESRD population. METHODS: Demographic and clinical factors affecting fistula patency and maturation were retrospectively compared among patients with incident ESRD aged <65 and ≥65 years at a single center. Fistula patency was estimated by Kaplan-Meier curves with log-rank test comparison. RESULTS: We analyzed 280 primary fistulas (59% radiocephalic, 33% brachiocephalic, and 8% brachiobasilic) in this cohort consisting of 31.8% aged ≥65 years, 50% Chinese, 39% Malay, 42% women, and 70% diabetic. One- and 2-year primary and secondary patency in patients aged <65 vs ≥65 years were comparable: 41.3% vs 36.7% and 28.7% vs 24.4% (P = .547) and 57.7% vs 56.8% and 47.1% vs 47.2% (P = .990). On multivariate analysis, only non-Chinese, dialysis initiation with tunneled catheters, and surgical/endovascular interventions affected fistula survival hazard ratios (HR): 0.622 (95% confidence interval [CI], 0.43-1.00), 0.549 (95% CI, 0.297-0.841), and 2.503 (95% CI, 1.695-3.697), respectively. Nonmaturation and intervention rates were also similar at 56.7% vs 61.8% and 34% vs 32.2% at 3 and 6 months and 0.31 vs 0.36 per access year, respectively (P > .05). Females and tunneled catheters were the only risk factors for nonmaturation (HR, 1.568; 95% CI, 1.148-1.608, and HR, 1.623; 95% CI, 1.400-1.881, respectively). CONCLUSIONS: A primary fistula strategy in incident elderly ESRD is feasible and does not result in inferior outcomes. Age should therefore not be a determinant for primary fistula creation.

Comparative outcomes of treated symptomatic versus non-treated asymptomatic high-grade central vein stenoses in the outflow of predominantly dialysis fistulas.

BACKGROUND: Witholding treatment in asymptomatic/pauci-symptomatic high-grade central vein stenosis (CVS), i.e. those not causing debilitating painful extremity oedema, the benefits of which have been shown in only one study in grafts, is debatable. The aim of our study was to assess the short- and long-term benefits of such a strategy in mainly autogenous fistulas. METHODS: We retrospectively compared the outcomes of 53 untreated asymptomatic/pauci-symptomatic and 50 symptomatic high-grade CVS treated by dilation with or without stenting between January 1998 and August 2010 at a single center. Central vein and access patency was estimated by Kaplan-Meier analysis. RESULTS: Mean age, central catheter use and location of stenosis (brachiocephalic vein) in asymptomatic/pauci-symptomatic and symptomatic CVS were significantly different at 69 versus 75 years, 28 versus 48% and 74 versus 56%, respectively. Ninety percent of the cases had an autogenous fistula. The mean degree of stenosis was >80%. Fourty percent of asymptomatic/pauci-symptomatic CVS became severely symptomatic after 4 years. Primary central vein patency at 3, 12, 24 and 36 months in asymptomatic/pauci-symptomatic and symptomatic CVS were 87±5 versus 82±6, 77±6 versus 55±9, 71±7 versus 35±9 and 67±7 versus 18±9%, respectively (P=0.002). Primary access circuit patency rate was not significantly different between the two groups with 66±5 versus 50±4% at 1 year. Secondary central vein and access circuit patency rates at 1 and 3 years were 100 and 93±7 versus 89±5 and 84±7% (P=0.014). CONCLUSIONS: Withholding treatment in asymptomatic/pauci-symptomatic CVS in dialysis fistulas yielded significantly better short- and long-term central vein patency than treatment of symptomatic cases without detrimental effects on overall dialysis circuit.