A systematic literature review to evaluate extended dosing intervals in the pharmacological management of acromegaly

PURPOSE

This systematic literature review investigated whether extended dosing intervals (EDIs) of pharmacological acromegaly treatments reduce patient burden and costs compared with standard dosing, while maintaining effectiveness.

METHODS

MEDLINE/Embase/the Cochrane Library (2001-June 2021) and key congresses (2018-2021) were searched and identified systematic literature review bibliographies reviewed. Included publications reported on efficacy/effectiveness, safety and tolerability, health-related quality of life (HRQoL), and patient-reported and economic outcomes in longitudinal/cross-sectional studies in adults with acromegaly. Interventions included EDIs of pegvisomant, cabergoline, and somatostatin receptor ligands (SRLs): lanreotide autogel/depot (LAN), octreotide long-acting release (OCT), pasireotide long-acting release (PAS), and oral octreotide; no comparator was required.

RESULTS

In total, 35 publications reported on 27 studies: 3 pegvisomant monotherapy, 11 pegvisomant combination therapy with SRLs, 9 LAN, and 4 OCT; no studies reported on cabergoline, PAS, or oral octreotide at EDIs. Maintenance of normal insulin-like growth factor I (IGF-I) was observed in ≥ 70% of patients with LAN (1 study), OCT (1 study), and pegvisomant monotherapy (1 study). Achievement of normal IGF-I was observed in ≥ 70% of patients with LAN (3 studies) and pegvisomant in combination with SRLs (4 studies). Safety profiles were similar across EDI and standard regimens. Patients preferred and were satisfied with EDIs. HRQoL was maintained and cost savings were provided with EDIs versus standard regimens.

CONCLUSIONS

Clinical efficacy/effectiveness, safety, and HRQoL outcomes in adults with acromegaly were similar and costs lower with EDIs versus standard regimens. Physicians may consider acromegaly treatment at EDIs, especially for patients with good disease control.

Evaluation of economic loss caused by Indian crested porcupine (Hystrix indica) in agricultural land of district Muzaffarabad, Azad Jammu and Kashmir, Pakistan

The Indian crested porcupine (Hystrix indica) is a vertebrate pest of agricultural lands and forest. The study was aimed to report the damage to local crops by the Indian crested porcupine (Hystrix indica) in the Muzaffarabad District. A survey was conducted to identify the porcupine-affected areas and assess the crop damage to the local farmers in district Muzaffarabad Azad Jammu and Kashmir (AJK) from May 2017 to October 2017. Around 19 villages were surveyed, and a sum of 191 semi-structured questionnaires was distributed among farmers. Crop damage was found highest in village Dhanni where a porcupine destroyed 175 Kg/Kanal of the crops. Regarding the total magnitude of crop loss, village Danna and Koomi kot were the most affected areas. More than half (51.8%) of the respondents in the study area suffered the economic loss within the range of 101-200$, and (29.8%) of the people suffered losses in the range of 201-300$ annually. Among all crops, maize (Zea mays) was found to be the most damaged crop ranging between 1-300 Kg annually. In the study area, porcupine also inflicted a lot of damages to some important vegetables, including spinach (Spinacia oleracea), potato (Solanum tuberosum) and onion (Allium cepa). It was estimated that, on average, 511Kg of vegetables are destroyed by porcupine every year in the agricultural land of Muzaffarabad. It was concluded that the Indian crested porcupine has a devastating effect on agriculture which is an important source of income and food for the local community. Developing an effective pest control strategy with the help of the local government and the Wildlife department could help the farmers to overcome this problem.

Thalassemia, a human blood disorder

A group of inherited blood defects is known as Thalassemia is among the world's most prevalent hemoglobinopathies. Thalassemias are of two types such as Alpha and Beta Thalassemia. The cause of these defects is gene mutations leading to low levels and/or malfunctioning α and β globin proteins, respectively. In some cases, one of these proteins may be completely absent. α and β globin chains form a globin fold or pocket for heme (Fe++) attachment to carry oxygen. Genes for alpha and beta-globin proteins are present in the form of a cluster on chromosome 16 and 11, respectively. Different globin genes are used at different stages in the life course. During embryonic and fetal developmental stages, γ globin proteins partner with α globin and are later replaced by β globin protein. Globin chain imbalances result in hemolysis and impede erythropoiesis. Individuals showing mild symptoms include carriers of alpha thalassemia or the people bearing alpha or beta-thalassemia trait. Alpha thalassemia causes conditions like hemolytic anemia or fatal hydrops fetalis depending upon the severity of the disease. Beta thalassemia major results in hemolytic anemia, growth retardation, and skeletal aberrations in early childhood. Children affected by this disorder need regular blood transfusions throughout their lives. Patients that depend on blood transfusion usually develop iron overload that causes other complications in the body systems like renal or hepatic impairment therefore, thalassemias are now categorized as a syndrome. The only cure for Thalassemias would be a bone marrow transplant, or gene therapy with currently no significant success rate. A thorough understanding of the molecular basis of this syndrome may provide novel insights and ideas for its treatment, as scientists have still been unable to find a permanent cure for this deadly disease after more than 87 years since it is first described in 1925.

Ecological impacts of climate change on the snow leopard (Panthera unica) in South Asia

Snow leopard (Panthera unica) is a felid which lives in the highly rugged areas of alpine regions in different mountain ranges of South and Central Asia. This solitary animal needs large spaces for its ranges but due to climate change and relatively faster rate of global warming in South Asian mountain ranges, its habitat is going to shrink and fragment by tree-line shifts and change in hydrology of the area. Vegetative modification of montane flora and competition with domestic goats will create its prey's population to decline along with a chance of a direct conflict and competition with the common leopard. Common leopard being more adaptable, grouped, and larger in size can be a significant stressor for a smaller and solitary snow leopard. Habitat would shrink, and snow leopard can possibly move upslope or northward to central Asian ranges and their predicted migratory patterns are unknown.

Abstract P5-16-17: Titanium-coated polypropylene mesh for immediate implant-based breast reconstruction – Our initial experience

Background: The use of titanium-coated polypropylene mesh (TCPM) is an alternative to a-cellular dermal matrix for the implant based breast reconstruction by providing extra implant coverage especially in the lower half. The aim of our study was to analyze short-term outcomes of TCPM based implant breast reconstruction and compare the patient- and procedure-related factors to implant loss and surgical complications.

Methods: Between 2013and 2016, implant breast reconstructions after conservative mastectomies using TCMP was performed in 50 patients (with 58 reconstructions). Complications were divided into major (need for additional surgery), minor (conservative treatment), and implant loss. Univariate analyses were performed to determine the influence of the patient- and procedure-related factors on postoperative complications and implant loss.

Results: Fifty patients had therapeutic mastectomies with 8 of them also had contra lateral risk reducing mastectomies. With median follow-up of 17.5 months, four of 50 patients had implant loss. Reasons for implant loss were skin necrosis in 2 cases, infection in 1 case and necrosis with infection in another case. One of these patients had a revised reconstruction one year later. One additional patient required implant replacement because of capsule contracture. No risk factors were observed for patient-associated complications. Univariate analysis revealed an increased risk for implant loss in patients with skin necrosis (p < 0.01).

Conclusions: This titanium-coated polypropylene mesh shows acceptable complication rates and its use in immediate implant breast reconstruction is safe and effective.

Citation Format: Munir A, Holt S, Huws A, Khan S, Shariaha Y, Khawaja S. Titanium-coated polypropylene mesh for immediate implant-based breast reconstruction – Our initial experience [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-16-17.

Abstract P2-01-22: The long term outcomes of Metasin RTqPCR intra-operative sentinel node analysis in early breast cancer

Background:

Axillary lymph node involvement is a prognostic factor in breast cancer and it is used to guide adjuvant therapy. Axillary clearance remains the standard of care in lymph node positive disease in most parts of the world. Usually this is performed as second procedure but immediate intra-operative node analysis allows clearance to be performed as part of the initial procedure where necessary.

The Metasin assay targets the breast epithelial cell markers CK19 and mammaglobin mRNA and detects the presence of breast tissue (metastatic disease) in the sentinel nodes. Evidence shows the Metasin assay to be fast (average assay time 41.2min) and accurate with a discordance rate below 4% compared with histology. The cost effectiveness of the assay has been reported in our previous studies.

Aim:

The aim of this study is to assess the risk of axillary recurrence following the use of the Metasin assay to guide axillary management.

Method:

This is a single centre retrospective study which included all patients presenting to a district general hospital with early clinically node negative breast cancer undergoing sentinel node biopsy between Oct 2011 and Dec 2014.

Alternate 2 mm slices of the node were examined intraoperatively using the Metasin assay and the remainder sent for histological examination. The results of the Metasin assay and histology were compared. The risk of axillary recurrence using the Metasin test to select patients for immediate axillary clearance was assessed.

Results:

1073 sentinel nodes from 545 patients were analysed during this three-year period. 2 patients were lost to follow up. 94 patients were node positive and underwent axillary clearance as part of their primary surgery. 449 patients had sentinel node biopsy with no further axillary procedure. There were 36 nodes (3.34%) with discordant results. Median follow up was 32 months (range 18 to 55 months).

Fourteen patients presented with recurrences (2.56%). The mean event free interval was 15 months. Of the 14 patients, 5 patients tested with Metasin had macrometastases and underwent immediate axillary clearance during the primary surgery. 7 patients were node negative and 2 patients were shown to have micrometastases. 11 patients recurred with distant metastases, 3 patients with local recurrence and 2 patients (0.36%) with axillary recurrences.

The two axillary recurrences occurred at 3 and 5 months after primary surgery. Both patients underwent Metasin intraoperative analyses of sentinel nodes which were negative. Subsequent histological examination confirmed no metastatic node involvement in one patient but micro-metastases in the other. Both of these patients had aggressive disease with local, axillary and distant metastasis and subsequently died of their disease.

Conclusions:

The Metasin assay is a reliable intraoperative test for sentinel node involvement and when used to guide surgical axillary management is associated with very low axillary recurrences (0.36% with a median follow up of 32 months).

Citation Format: Udayasankar S, Ashley E, Jenkins KS, Huws A, Sharaiha Y, Sai-Giridhar P, Thomas D, Munir A, Holt S, Khawaja S. The long term outcomes of Metasin RTqPCR intra-operative sentinel node analysis in early breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-01-22.

Abstract P1-05-21: A comparison of oncotype DX recurrence scores in a screen detected vs a symptomatic cohort of patients with breast cancer: A UK experience

Background:

In the Western World, it has been stated that breast cancers detected on a screening program are indolent. There have been many recent publications stating that breast screening is overdiagnosing and therefore overtreating patients with breast cancer. With the advent of genomic testing, it can now be determined which patients have an aggressive tumor requiring systemic chemotherapy. We therefore conducted a retrospective study in the UK on patients having oncotype DX testing in both screen detected and symptomatic cancers.

Materials and Methods:

Patients in our institution undergoing oncotype DX testing for invasive breast cancer which was ER positive and node negative were part of this study. The detection of the breast cancer was documented as either a screening case or a symptomatic one. The recurrence scores of the oncotype DX testing was then compared in the screening versus the symptomatic cohort.

Results:

155 patients were included in this study. They underwent Oncotype DX testing between 2008 to 2016. The age of the patients ranged from between 31 years to 78 years. Eighty-nine patients were reported to have a low recurrence score; 45 had an intermediate score; and 21 had a high result. Fifty eight patients were screen detected, while 97 patients were symptomatic presentations. In the screening population, 32 patients had a low recurrence score; 22 had an intermediate result and 4 had a high recurrence score resulting in the latter groups being considered for chemotherapy. In the symptomatic cohort, 57 had a low recurrence score; 23 had an intermediate result; and 17 had a high score.

Conclusion:

The results of our study depict that even patients in a screeining cohort will have a high number of intermediate recurrence scores and some with a high recurrence score. This shows that the hypothesis that screening detects a majority of breast cancers which are indolent not requiring further systemic treatment should be looked at again in light of our results with genomic testing.

Citation Format: Khawaja S, Parab A, Thomas D, Huws A, Munir A, Udayasankar S, Sharaiha Y, Holt S. A comparison of oncotype DX recurrence scores in a screen detected vs a symptomatic cohort of patients with breast cancer: A UK experience [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-05-21.

Abstract P1-03-12: A simulation study depicting the inconsistency of adjuvant online compared to genomic testing when determining the benefit of chemotherapy

Background: Prognostic factors have been used for years to determine the benefit of adjuvant chemotherapy in breast cancer. However, reporting of the size and grade of the tumor are affected by interobserver variability in reporting. This can result in a change in the results of adjuvant online and an impact on decision making of chemotherapy. On the contrary, genomic testing such as oncotype Dx is reproducible. The purpose of our study was to assess the effect of pathological discordance on the adjuvant online results on a cohort of patients who also underwent oncotype Dx testing.

Materials and Methods: A total of 143 patients' histologies were included in this study. The results of the Phase III WSG-Plan B trial concerning central vs. local grade discrepancy rates were utilized to randomly change the grade of the tumors. 61 percent of grade 1 cancers were upgraded to grade 2 and 2% upgraded to grade 3. 4 percent of grade 2 cancers were downgraded to grade 1 and 26% were upgraded to grade 3. 1 percent of grade 3 cancers were downgraded to grade 1 and 25% were downgraded to grade 2. Likewise, change was made in the size of the tumor in 20 percent of patients. 8 to 10mm, 18-20, 28-30, and 48-50mm changed to 11, 21, 31 and 51mm respectively. 11-13mm, 21-23, 31-33, and 51-53mm was changed to 10, 20, 30, and 50mm. Ten percent of patients had the ER and Her 2 status changed.

Results: The simulation results showed that when the grade was only altered, the spearman correlation of the predicted 10 year mortality on adjuvant online with the original data was significantly changed from 1 to a result of 0.788. When the changed size was additionally added, the coefficient was 0.836. With the altered ER status, the result was 0.749 and with the Her 2 change, the spearman correlation was minimally changed to 0.742. The scattergrams showed a large number of outliers when the alteration in size was added to the altered grade.

Conclusion: Our simulation study confirms that with minimal changes in the clinical parameters because of the lack of perfect correlation between pathologist's results, there is a significant difference in the 10 year predicted mortality on adjuvant online. This is one step further in understanding the lack of correlation between adjuvant online and oncotype Dx, and the inconsistency of chemotherapy decision making with the sole use of adjuvant online.

Citation Format: Khawaja S, Thomas D, Udayasankar S, Munir A, Huws A, Sharaiha Y, Holt S. A simulation study depicting the inconsistency of adjuvant online compared to genomic testing when determining the benefit of chemotherapy [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-03-12.

Reliability of different body temperature measurement sites during aortic surgery

OBJECTIVE

We retrospectively performed a comparative analysis of temperature measurement sites during surgical repair of the thoracic aorta.

METHODS

Between January 2004 and May 2006, 22 patients (mean age: 63 ± 12 years) underwent operations on the thoracic aorta with arterial cannulation of the aortic arch concavity and selective antegrade cerebral perfusion (ACP) during deep hypothermic circulatory arrest (HCA). Indications for surgical intervention were acute type A dissection in 14 (64%) patients, degenerative aneurysm in 6 (27%), aortic infiltration of thymic carcinoma in 1 (4.5%) and intra-aortic stent refixation in 1 (4.5%). Rectal, tympanic and bladder temperatures were evaluated to identify the best reference to arterial blood temperature during HCA and ACP.

RESULTS

There were no operative deaths and the 30-day mortality rate was 13% (three patients). Permanent neurological deficits were not observed and transient changes occurred in two patients (9%). During re-warming, there was strong correlation between tympanic and arterial blood temperatures (r = 0.9541, p<0.001), in contrast to the rectal and bladder temperature (r = 0.7654, p = n.s; r = 0.7939, p = n.s., respectively).

CONCLUSION

We conclude that tympanic temperature measurements correlate with arterial blood temperature monitoring during aortic surgery with HCA and ACP and, therefore, should replace bladder and rectal measurements.

A decision impact, decision conflict and economic assessment of routine Oncotype DX testing of 146 women with node-negative or pNImi, ER-positive breast cancer in the U.K

Background:

Tumour gene expression analysis is useful in predicting adjuvant chemotherapy benefit in early breast cancer patients. This study aims to examine the implications of routine Oncotype DX testing in the UK.

Methods:

Women with oestrogen receptor positive (ER+), pNO or pN1mi breast cancer were assessed for adjuvant chemotherapy and subsequently offered Oncotype DX testing, with changes in chemotherapy decisions recorded. A subset of patients completed questionnaires about their uncertainties regarding chemotherapy decisions pre- and post-testing. All patients were asked to complete a diary of medical interactions over the next 6 months, from which economic data were extracted to model the cost-effectiveness of testing.

Results:

Oncotype DX testing resulted in changes in chemotherapy decisions in 38 of 142 (26.8%) women, with 26 of 57 (45.6%) spared chemotherapy and 12 of 85 (14.1%) requiring chemotherapy when not initially recommended (9.9% reduction overall). Decision conflict analysis showed that Oncotype DX testing increased patients' confidence in treatment decision making. Economic analysis showed that routine Oncotype DX testing costs £6232 per quality-adjusted life year gained.

Conclusion:

Oncotype DX decreased chemotherapy use and increased confidence in treatment decision making in patients with ER+ early-stage breast cancer. Based on these findings, Oncotype DX is cost-effective in the UK setting.

Abstract P1-01-18: The results of 55 consecutive cases of intra-operative sentinel node analysis using real time polymerase chain reaction detection of cytokeratin 19 and mammoglobin expression (Metasin) to direct immediate axillary clearance

The standard management of early beast cancer is complete excision of the primary from the breast by either wide local excision or mastectomy and sentinel node biopsy to stage the axilla. The standard of care in the UK remains clearance of the axilla in node positive patients. Unless immediate multiple frozen section histology is available, positive patients require a second operation between 3 and 6 weeks later, with the associated increased cost, inconvenience and risk.

By using the real time polymerase chain reaction (PCR) to detect mammary derived cells in the sentinel lymph nodes (SLN), we aim to provide the surgeon with a reliable indicator of the presence or absence of nodal macro-metastases within a timeframe that will allow axillary clearance to be performed under the same anaesthetic as the initial surgery. We detect cytokeratin 19 (CK19) or mammoglobin within the lymph node using reagents developed by the UK National Health Service under the name Metasin.

Method: 55 consecutive patients undergoing SLN biopsy as part of their initial treatment for early breast cancer were tested using the Metasin. The nodes were divided into 2mm slices and alternate sections submitted to PCR and the remainder to conventional histology. The results were compared and an assessment of the costs made. The time taken report the Metasin result to the surgeon was recorded.

Results: Five patients had positive results by Metasin and proceeded to immediate axillary clearance. When compared to histology there were no false positive results (0%). Two patients were negative on Metasin testing with the threshold set at 2 mm but positive on histology (3.6%). The average time for the test was 43.2 minutes and the mean number of lymph nodes was 2.3. The average cost is £40 to test 2 nodes.

Discussion: The test is accurate. The two false negative cases were found to be due to the sampling, the metastases being only present by chance in the histologically examined specimens and not due to assay failure. The total cost to run the test for 55 patients was £2,520. The cost for completion axillary clearance as a separate procedure is estimated at £2,227. The total saving for 5 cases is about £11,000, making the test cost saving as well as safer, more acceptable to the patients and limiting delay in starting adjuvant therapies. The additional time of surgery caused by using Metasin was minimal.

Conclusion: Metasin has become our standard of care in patients requiring SLN biopsy and generally avoids second surgeries to clear the axilla in positive cases. We are considering analyzing the complete node using this technique and this would eliminate false negatives caused by sampling and offer further cost savings in the histology department.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-01-18.

Comparison of methods to detect recent HIV type 1 infection in cross-sectionally collected specimens from a cohort of female sex workers in the Dominican Republic

Interest in estimating HIV-1 incidence using specimens obtained as part of cross-sectional surveys has led to the development of new methods to detect recent HIV-1 infection through the testing of a single anti-HIV-positive specimen. These assays are based on quantitative and qualitative differences in anti-HIV-1 antibodies between recent and long-standing infections. An ongoing vaccine preparedness study enrolled female sex workers in the Dominican Republic. Specimens from women found to be HIV positive at baseline were tested for recent HIV-1 infection using the detuned assay, avidity index, and BED-CEIA assay. An unweighted kappa statistic in pairwise comparisons was used to estimate the correlation of recent HIV-1 infection detection by the three methods. Nineteen (3.9%) of 482 women were positive for HIV-1 infection. The incidence of HIV infection was 1.4% [95% confidence interval (CI): 0.2, 5.3], 0.9%(95% CI: 0.1, 4.4), and 1.0%(95% CI: 0.1, 4.4) using detuned assay, avidity index, and BED-CEIA techniques, respectively. The overall agreement between both detuned assay and avidity index and detuned assay and BED-CEIA was 94%(kappa = 0.8, 95% CI; 0.3, 1.0). The correlation was highest between BED-CEIA and avidity index methods (100%; kappa = 1.0). All three methods performed similarly in detecting recent HIV-1 infection in this region dominated by clade B HIV-1 infection. Although incidence estimates were slightly higher using the detuned assay method, they were not significantly different. These assays may be of value in both clinical research and practice. The utility of individual assays for recent infection detection will depend upon operating characteristics, HIV-1 subtype limitations, and selection of appropriate assay cutoff values.

Involvement of a heterotrimeric G protein alpha subunit in tight junction biogenesis

The tight junction (TJ) of polarized epithelial cells is critical for maintaining an impermeant barrier and epithelial cell polarity. The signaling events important for TJ assembly require regulated calcium stores and protein kinase C (PKC), but the earliest signaling events in the cascade have not been well defined. We now show that Galphai2 in Madin Darby canine kidney (MDCK) cells localizes to a region overlapping with the TJ. To further analyze the localization of Galpha subunits in epithelial cells, rat Galphao, Q205Lalphao (Galphao "activated" by point mutation) and plasmid without insert (PC) were transfected into MDCK cells and localized by immunofluorescence and confocal microscopy. Similar to endogenous Galphai2, Galphao-MDCK cells localize Galphao, (84% similar to Galphai2) in the subapical region overlapping with ZO-1 (zona occludens-I), a key component of the TJ. PC-MDCK cells have no detectable Galphao. In Galphao-MDCK cells, a physical association of Galphao with components of the TJ was detectable by immunoprecipitation of ZO-1. Immunoprecipitates of ZO-1 from Galphao-MDCK cells consistently coprecipitated Galphao. Constitutively active Q205LGalphao localized to the subapical lateral membrane similar to wild-type Galphao. To determine if constitutively activated Galpha subunits can affect TJ biogenesis, the formation of tight junctions in PC, Galphao, and Q205Lalphao-MDCK cells was followed by measurement of transepithelial resistance (TER) during the Ca2+ switch, a model widely used to study mechanisms of junctional assembly. Baseline and post Ca2+ switch TER values did not differ among the cell lines. However, constitutively activated Q205Lalphao-MDCK cells developed TER significantly faster than PC and Galphao cells in the early phase (0-4 h) (54 +/- 4 versus 23 +/- 3 (PC); 12 +/- 1 (Galphao) Omega.m2/h) and late phase (4-h peak) (117 +/- 10 versus 45 +/- 5 (PC); 66 +/- 7 (Galphao) Omega.m2/h) after Ca2+ switch. Peak TER values were significantly higher in Q205Lalphao-MDCK cells (1168 +/- 107 versus 437 +/- 37 (PC); 548 +/- 54 (Galphao) Omega.cm2). These results indicate that Galphao and Q205Lalphao expressed in MDCK cells are localized near the junctional complex, associate with at least one TJ protein, and that activated Galphao accelerates TJ biogenesis without significantly affecting the maintenance of the TJ. Together, these results suggest an important role for heterotrimeric G proteins in TJ assembly.

Molecular characteristics of Na(+)-coupled glucose transporters in adult and embryonic rat kidney

Two distinct Na(+)-coupled glucose transporters (SGLTs) with either a high or a low affinity for glucose were shown to provide reabsorption of filtered glucose in the kidney. We have previously reported the characteristics of the high affinity Na+/glucose cotransporter SGLT1 from rabbit, rat, and human kidney and the low affinity Na+/glucose cotransporter SGLT2 from human kidney. Because the molecular identity of SGLT2 as the kidney cortical low affinity Na+/glucose cotransporter has been recently challenged based on studies of the porcine low affinity Na+/glucoe cotransporter SAAT-pSGLT2 (Mackenzie, B., Panayotova-Heiermann, M., Loo, D. D. F., Lever, J.E., and Wright, E. M. (1994) J. Biol. Chem. 269, 22488-22491), we have reevaluated the properties of SGLT2 in greater detail. We furthermore report new data on the regulation of SGLT1 and SGLT2 during kidney development. To analyze and compare SGLT1 and SGLT2 in adult and embryonic kidney, we have cloned and characterized SGLT2 from rat kidney and determined its tissue distribution based on Northern analysis and in situ hybridization. When expressed in Xenopus oocytes, rat SGLT2 stimulated transport of alpha-methyl-D-glucopyranoside (2 mM) in oocytes up to 4.5-fold over controls with an apparent Km of 3.0 mM. The transport properties (i.e. a Na+ to glucose coupling of 1:1 and lack of galactose transport) generally matched those of the kidney cortical low affinity system. We show that expression of rat SGLT2 mRNA is kidney specific and that it is strongly and exclusively expressed in proximal tubule S1 segments. Hybrid-depletion studies were performed to conclusively determine whether SGLT2 corresponds to the kidney cortical low affinity system. Injection of rat kidney superficial cortex mRNA into oocytes stimulated the uptake of alpha-methyl-D-glucopyranoside (2 mM) 2-3-fold. We show that hybrid depletion of this kidney RNA using an SGLT2 antisense oligonucleotide completely suppresses the uptake. These data strongly indicate that SGLT2 is the major kidney cortical low affinity glucose transporter. We therefore propose that SAAT-pSGLT2 be renamed SGLT3. Experiments addressing the expression of SGLT1 and SGLT2 mRNAs in embryonic rat kidneys reveal that the two Na+/glucose cotransporters are developmentally regulated and that there may be a different splice variant for SGLT2 in embryonic kidney compared to the adult.

The neuronal and epithelial human high affinity glutamate transporter. Insights into structure and mechanism of transport

High affinity transport of glutamate across plasma membranes of brain neurons and epithelial is mediated by a Na(+)- and K(+)-coupled electrogenic transporter. Here we report the primary structure and functional characterization of the human high affinity glutamate transporter (HEAAC1). A unique characteristic of HEAAC1-mediated transport is that the affinity for glutamate and the maximal transport rate are strongly dependent on membrane potential. Our data provide new insights into individual steps of high affinity glutamate transport and show that the transport mechanism is distinct from that of the gamma-aminobutyric acid transporter GAT-1 and the Na+/glucose transporter SGLT1. Under voltage clamp condition, HEAAC1 mediated large substrate-evoked inward currents (up to 1 microA). The substrate specificity, stereospecificity, the Km value (30 +/- 3 microM at -60 mV) of the L-glutamate-evoked current, and Northern analysis all agree with previously reported characteristics of high affinity glutamate transport in brain. In contrast to SGLT1 and GAT-1, voltage jump studies of HEAAC1 yielded only minor relaxation currents. Classic inhibitors of brain glutamate uptake such as DL-threo-beta-hydroxyaspartate, L-trans-pyrrolidine 2,4,-dicarboxylic acid (PDC), and dihydrokainate were found to be either transport substrates or to have no significant effect on glutamate transport. We also found that the maximal transport rate for PDC was markedly reduced compared to that for L-glutamate. We propose that PDC most likely reduces the turnover rate of the transporter. A search of the sequence data bases revealed weak homology of HEAAC1 to the H(+)-coupled vesicular monoamine transporter, suggesting an evolutionary link between plasma membrane and vesicular transporters.

Colostomy complications in infants and children

Seventy-seven colostomies were performed in 74 patients: 35 for high anorectal agenesis, 34 for Hirschsprung's disease, 2 for necrotizing enterocolitis, 2 for small left colon syndrome, and 1 for volvulus neonatorum with perforation. There were 55 boys and 19 girls with a mean age of 0.8 years. The different types of colostomies performed were: transverse loop in 48, sigmoid loop in 21, transverse end in 4, descending end in 2, sigmoid end in 1, and transverse double barrel in 1. Forty-seven patients developed stomal complications (74.6%). Eleven patients died, but only in 2 (2.7%) were the deaths directly related to colostomy formation. Five patients required stomal revision (6.8%). The incidence of complications was neither related to the age nor to the primary indication for the colostomy, but sigmoid colostomy was associated with a lower complication rate compared to transverse colostomy (52% versus 81% 0.02 greater than p greater than 0.01). A sigmoid loop colostomy should be used whenever possible.

Congenital diaphragmatic hernia: Update on regional experience

A consecutive series of 34 patients with congenital diaphragmatic hernia are reported from a tertiary neonatal care unit in the Eastern Province. All the patients presented within the first 24 hours of life with left-sided defect. The overall mortality (56%) and postoperatiVE mortality (44%) are comparable with reports from other centers. The outcome of treatment correlated well with the age on presentation, the size of the defect, and preoperative blood gas results. Our approach to management has been modified lately, in the light of recent experience from other centers. The surgery is delayed until the neonate is stabilized with biochemical values of PaCO2 = 45 torr or less; pH = 7.2 or higher; and PaO2 = 50 torr or more. This management policy did not adversely affect overall survival. The problem encountered with patient transfer and the need for continued improvement in the organization of regionalized care are highlighted.

Splenectomy in compound heterozygous hemoglobinopathies in Saudi Arabia

Hemoglobinopathies are a major public health problem in Saudi Arabia. We studied the effect of splenectomy in 16 Saudi Arabian children with compound hemoglobinopathies. Seven patients no longer require regular blood transfusions, and transfusion requirements were decreased by 30 to 60% in the other eight patients. Three patients whose heights and weights were below the 5th percentile before splenectomy reached the 25th percentile 1 year after the surgery. In spite of preoperative pneumococcal vaccination and the penicillin prophylaxis after the surgery, one patient died of Haemophilus influenzae Group B bacteremia, and three others had six episodes of pneumonia.

Generation of a stable, posttranslationally modified microtubule array is an early event in myogenic differentiation

Microtubules (MTs) have been implicated to function in the change of cell shape and intracellular organization that occurs during myogenesis. However, the mechanism by which MTs are involved in these morphogenetic events is unclear. As a first step in elucidating the role of MTs in myogenesis, we have examined the accumulation and subcellular distribution of posttranslationally modified forms of tubulin in differentiating rat L6 muscle cells, using antibodies specific for tyrosinated (Tyr), detyrosinated (Glu), and acetylated (Ac) tubulin. Both Glu and Ac tubulin are components of stable MTs, whereas Tyr tubulin is the predominant constituent of dynamic MTs. In proliferating L6 myoblasts, as in other types of proliferating cells, the level of Glu tubulin was very low when compared with the level of Tyr tubulin. However, when we shifted proliferating L6 cells to differentiation media, we observed a rapid accumulation of Glu tubulin in cellular MTs. By immunofluorescence, the increase in Glu tubulin was first detected in MTs of prefusion myoblasts and was specifically localized to MTs that were associated with elongating portions of the cell. MTs in the multinucleated myotubes observed at later stages of differentiation maintained the elevated level of Glu tubulin that was observed in the prefusion myoblasts. When cells at early stages of differentiation (less than 1 d after switching the culture medium) were immunostained for Glu tubulin and the muscle-specific marker, muscle myosin, we found that the increase in Glu tubulin preceded the accumulation of muscle myosin. Thus, the elaboration of Glu MTs is one of the very early events in myogenesis. Ac tubulin also increased during L6 myogenesis; however, the increase in acetylation occurred later in myogenesis, after fusion had already occurred. Because detyrosination was temporally correlated with early events of myogenesis, we examined the mechanism responsible for the accumulation of Glu tubulin in the MTs of prefusion myoblasts. We found that an increase in the stability of L6 cell MTs occurred at the onset of differentiation, suggesting that the early increase in detyrosination that we observed is a manifestation of a decrease in MT dynamics in elongating myoblasts. We conclude that the establishment of an oriented array of microtubules heightened in its stability and its level of posttranslationally modified subunits may be involved in the subcellular remodeling that occurs during myogenesis.

Percutaneous transtracheal high frequency jet ventilation as an aid to difficult intubation

A case is described where prophylactic high frequency jet ventilation through a percutaneous transtracheal cannula was performed. This guaranteed adequate ventilation of a patient who was known to be difficult to intubate, enabling a paralyzing dose of succinylcholine to be given and intubation to be performed safely in a well oxygenated patient scheduled for coronary artery bypass grafting.

Somatostatin modulates cholinergic neurotransmission in canine antral muscle

Somatostatin has been shown to inhibit antral motility in vivo. To examine the effect of somatostatin on cholinergic neurotransmission in the canine antrum, we studied the mechanical response of and the release of [3H]acetylcholine from canine longitudinal antral muscle in response to substance P, gastrin 17, and electrical stimulation. In unstimulated tissues, somatostatin had a positive inotropic effect on spontaneous phasic contractions. In tissues stimulated with substance P and gastrin 17, but not with electrical stimulation, somatostatin inhibited the phasic inotropic response dose dependently. This inhibitory effect was abolished by indomethacin. Somatostatin stimulated the release of prostaglandin E2 radioimmunoreactivity, and prostaglandin E2 inhibited the release of [3H]acetylcholine induced by substance P and electrical stimulation. Somatostatin increased the release of [3H]acetylcholine from unstimulated tissues by a tetrodotoxin-sensitive mechanism but inhibited the release induced by substance P and electrical stimulation. These results suggest that somatostatin has a dual modulatory effect on cholinergic neurotransmission in canine longitudinal antral muscle. This effect is excitatory in unstimulated tissues and inhibitory in stimulated tissues. The inhibitory effect is partially mediated by prostaglandins.

Enhanced stability of microtubules enriched in detyrosinated tubulin is not a direct function of detyrosination level

Interphase cultured monkey kidney (TC-7) cells contain distinct subsets of cellular microtubules (MTs) enriched in posttranslationally detyrosinated (Glu) or tyrosinated (Tyr) alpha tubulin (Gundersen, G. G., M. H. Kalnoski, and J. C. Bulinski. 1984. Cell. 38:779-789). To determine the relative stability of these subsets of MTs, we subjected TC-7 cells to treatments that slowly depolymerized MTs. We found Glu MTs to be more resistant than Tyr MTs to depolymerization by nocodazole in living cells, and to depolymerization by dilution in detergent-permeabilized cell models. However, in cold-treated cells, Glu and Tyr MTs did not differ significantly in their stability. Digestion of permeabilized cell models with pancreatic carboxypeptidase A, to generate Glu MTs from endogenous Tyr MTs, did not significantly alter the resistance of the endogenous Tyr MTs toward dilution-induced depolymerization. Furthermore, in human fibroblasts that contained no distinct Glu MTs, we observed a population of nocodazole-resistant MTs. These data suggest that Glu MTs possess enhanced stability against end-mediated depolymerization, yet detyrosination alone appears to be insufficient to confer this enhanced stability.

Postpolymerization detyrosination of alpha-tubulin: a mechanism for subcellular differentiation of microtubules

Tyrosinated (Tyr) and detyrosinated (Glu) alpha-tubulin, species interconverted by posttranslational modification, are largely segregated in separate populations of microtubules in interphase cultured cells. We sought to understand how distinct Tyr and Glu microtubules are generated in vivo, by examining time-dependent alterations in Tyr and Glu tubulin levels (by immunoblots probed with antibodies specific for each species) and distributions (by immunofluorescence) after microtubule regrowth and stabilization. When microtubules were allowed to regrow after complete depolymerization by microtubule antagonists, Glu microtubules reappeared with a delay of approximately 25 min after the complete array of Tyr microtubules had regrown. In these experiments, Tyr tubulin immunofluorescence first appeared as an aster of distinct microtubules, while Glu tubulin staining first appeared as a grainy pattern that was not altered by detergent extraction, suggesting that Glu microtubules were created by detyrosination of Tyr microtubules. Treatments with taxol, azide, or vinblastine, to stabilize polymeric tubulin, all resulted in time-dependent increases in polymeric Glu tubulin levels, further supporting the hypothesis of postpolymerization detyrosination. Analysis of monomer and polymer fractions during microtubule regrowth and in microtubule stabilization experiments were also consistent with postpolymerization detyrosination; in each case, Glu polymer levels increased in the absence of detectable Glu monomer. The low level of Glu monomer in untreated or nocodazole-treated cells (we estimate that Glu tubulin comprises less than 2% of the monomer pool) also suggested that Glu tubulin entering the monomer pool is efficiently retyrosinated. Taken together these results demonstrate that microtubules are polymerized from Tyr tubulin and are then rapidly converted to Glu microtubules. When Glu microtubules depolymerize, the resulting Glu monomer is retyrosinated. This cycle generates structurally, and perhaps functionally, distinct microtubules.

Anesthetic considerations in Beckwith-Wiedemann syndrome

The anesthetic management of a thirty-month-old male with Beckwith-Wiedemann Syndrome is described. The presentation and features of this syndrome are described and the problems of providing anesthesia in such patients are discussed.

Characterization of substance P effects on canine antral muscle

Synthetic substance P increased the frequency and amplitude of spontaneously occurring contractions of circular and longitudinal muscle strips from canine gastric antrum in vitro. In longitudinal muscle, ED50 values calculated for frequency and amplitude were 3.7 X 10(-9) M and 9.7 X 10(-7) M, respectively. The effect of substance P on frequency in both layers and on amplitude in the circular layer was myogenic and unrelated to receptors for acetylcholine, norepinephrine, serotonin, histamine, and enkephalins. In the longitudinal muscle the amplitude response was partially inhibited by tetrodotoxin, atropine, and hexamethonium. The effect on amplitude but not on frequency was dependent on extracellular calcium. When compared to other stimulants of antral muscle contraction, the biological potency of substance P was higher than that of acetylcholine but significantly lower than that of gastrin and bombesin. Two putative substance P antagonists ([D-Pro2,D-Phe7,D-Trp9]substance P and [D-Pro2, D-Trp7,9]substance P) did not block the response of longitudinal muscle to substance P. Only the chronotropic response to substance P showed consistent, prolonged desensitization. These findings suggest that the mechanisms mediating the response to substance P in the canine antrum are different from other reported tissues.

Potency of natural and synthetic canine gastrin-releasing decapeptide on canine antral muscle

The carboxyl terminal decapeptide of gastrin-releasing peptide (GRP-10), a small, naturally occurring bombesin-like peptide, has been isolated from canine antral muscle, synthesized, and its bioactivity compared with other synthetic and natural gastrin-releasing peptides on stimulation of spontaneously occurring contractions of canine circular antral muscle in vitro. Concentrations of peptides were verified by amino acid analysis and radioimmunoassay. In this system three forms of natural canine GRP, synthetic GRP-10, synthetic porcine gastrin-releasing heptacosapeptide (GRP-27), [Gln3]GRP-10, and [Arg3]GRP-10 all were similar in potency to synthetic amphibian bombesin. These results differ from the low activity of GRP-10 previously reported in rat brain. The full biological potency on canine antral motility and the presence of GRP-10 in nerve fibers in the gut and in the spinal cord suggest a possible role for this peptide as a neurotransmitter or neuromodulator in regulation of smooth muscle contraction.