Trimethyloxonium modification of single batrachotoxin-activated sodium channels in planar bilayers. Changes in unit conductance and in block by saxitoxin and calcium

Single batrachotoxin-activated sodium channels from rat brain were modified by trimethyloxonium (TMO) after incorporation in planar lipid bilayers. TMO modification eliminated saxitoxin (STX) sensitivity, reduced the single channel conductance by 37%, and reduced calcium block of inward sodium currents. These effects always occurred concomitantly, in an all-or-none fashion. Calcium and STX protected sodium channels from TMO modification with potencies similar to their affinities for block. Calcium inhibited STX binding to rat brain membrane vesicles and relieved toxin block of channels in bilayers, apparently by competing with STX for the toxin binding site. These results suggest that toxins, permeant cations, and blocking cations can interact with a common site on the sodium channel near the extracellular surface. It is likely that permeant cations transiently bind to this superficial site, as the first of several steps in passing inward through the channel.     

In vitro histamine H2-antagonist activity of the novel compound HUK 978

Histamine stimulated adenylate cyclase from guinea-pig fundic mucosa and 3H-tiotidine binding in guinea-pig cerebral cortex were used to assess the in-vitro histamine H2-activity of the novel H2-antagonist HUK 978. The results showed that HUK 978 was a more potent H2-antagonist than either cimetidine or ranitidine. HUK 978 was also shown to be devoid of activity at the histamine H1-receptor, the muscarinic receptor and the alpha and beta-adrenergic receptors.     

Failure to detect intra-abdominal metastases from breast cancer: a case for staging laparotomy

Two studies were performed to assess the accuracy of non-invasive methods in detecting intra-abdominal metastases from breast cancer. Firstly, the sites of spread detected at the time of first presentation with metastases were compared with the sites of spread shown at necropsy in the same patients. Although about two-thirds of the patients with bone and lung metastases at necropsy had had metastases detected at these sites when they first presented with metastases, only a third of the patients with liver metastases and none of those with other intra-abdominal metastases had had evidence of disease at first presentation with metastases. The second study confirmed a poor detection rate of liver and other intra-abdominal metastases in patients with breast cancer undergoing laparotomy and oophorectomy who were staged immediately before operation.Pre-mastectomy staging laparotomy should be considered in those patients with primary breast cancer who are most likely to have disseminated disease beyond the regional nodes. In the presence of occult gross metastases detected by staging laparotomy, mastectomy will not provide additional protection against loca recurrence of disease. Patients with occult gross metastases should also be excluded from studies on adjuvant chemotherapy (designed to treat micrometastases). Aggressive methods of staging are justified to protect the patient as far as possible against unnecessary mastectomy and to identify those patients who should be treated by therapeutic chemotherapy rather than adjuvant chemotherapy.     

Survey of treatment of primary breast cancer in Great Britain.

A postal survey of current management of breast cancer among surgeons in Great Britain was carried out. The results showed that there is no consensus among surgeons about the treatment of primary breast cancer. Many different types of primary surgery are practised, and patterns of referral for postoperative radiotherapy vary widely. Adjuvant systemic treatment is given often by some surgeons and not at all by others. Few patients are entered into controlled randomised trials.     

Prenatal screening for trisomy 18 with free beta human chorionic gonadotrophin as a marker.

OBJECTIVE--To determine the relation between maternal serum alpha fetoprotein and free beta human chorionic gonadotrophin concentrations in pregnancies complicated by trisomy 18 and establish whether prenatal biochemical screening for this condition could be developed in a way similar to that proposed for trisomy 21. DESIGN--Serum alpha fetoprotein and free beta human chorionic gonadotrophin concentrations in women with singleton pregnancies affected by cytogenetically confirmed trisomy 18, uncomplicated by neural tube defect or ventral wall defect, were identified from prospective trisomy 21 screening programmes. Additionally, stored maternal serum from similar pregnancies was analysed retrospectively. Analyte concentrations from singleton unaffected pregnancies were identified from a prospective screening programme as controls. Statistical parameters of the affected and unaffected populations were compiled. SETTING--Biochemical screening laboratories in Britain and the United States. SUBJECTS--52 women with singleton pregnancies complicated by trisomy 18; control population of 6661 women with unaffected singleton pregnancies. MAIN OUTCOME MEASURES--Median values of each analyte and their distribution in the affected and unaffected populations; detection rate of trisomy 18 and the false positive rate. RESULTS--Maternal serum alpha fetoprotein and free beta human chorionic gonadotrophin concentrations were significantly lower in pregnancies complicated by trisomy 18 (median values 0.71 and 0.37 respectively). By using a multivariate risk algorithm incorporating maternal age risk of trisomy 18 and the concentration of the two biochemical markers it was predicted that 50% of trisomy 18 cases (unaffected by neural tube defect or ventral wall defect) could be detected with a 1% false positive rate. CONCLUSION--Second trimester biochemical screening for trisomy 18 could be a valuable addition to trisomy 21 screening programmes.     

Operation Crayweed: Ecological and sociocultural aspects of restoring Sydney’s underwater forests

Operation Crayweed focuses on the restoration of underwater forests that disappeared from the coastline of Sydney, Australia’s largest city, 40 years previously. We show how a combination of science, hands‐on restoration, community engagement and art has helped the project to reach its goals as well as raise awareness about the importance of underwater kelp forests that are experiencing global decline.     

Influence of Plasma Processing on Recovery and Analysis of Circulating Nucleic Acids

Circulating nucleic acids (CNAs) are under investigation as a liquid biopsy in cancer. However there is wide variation in blood processing and methods for isolation of circulating free DNA (cfDNA) and microRNAs (miRNAs). Here we compare the extraction efficiency and reproducibility of 4 commercially available kits for cfDNA and 3 for miRNA using spike-in of reference templates. We also compare the effects of increasing time between venepuncture and centrifugation and differential centrifugation force on recovery of CNAs. cfDNA was quantified by TaqMan qPCR and targeted deep sequencing. miRNA profiles were assessed with TaqMan low-density arrays and assays. The QIAamp^® DNA Blood Mini and Circulating nucleic acid kits gave the highest recovery of cfDNA and efficient recovery (>90%) of a 564bp spike-in. Moreover, targeted sequencing revealed overlapping cfDNA profiles and variant depth, including detection of HER2 gene amplification, using the Ion AmpliSeq™Cancer Hotspot Panel v2. Highest yields of miRNA and the synthetic Arabidopsis thaliana miR-159a spike-in were obtained using the miRNeasy Serum/Plasma kit, with saturation above 200 µl of plasma. miRNA profiles showed significant variation with increasing time before centrifugation (p<0.001) and increasing centrifugation force, with depletion of platelet associated miRNAs, whereas cfDNA was unaffected. However, sample replicates showed excellent reproducibility on TaqMan low density arrays (ρ = 0.96, p<0.0001). We also successfully generated miRNA profiles for plasma samples stored > 12 years, highlighting the potential for analysis of stored sample biobanks. In the era of the liquid biopsy, standardisation of methods is required to minimise variation, particularly for miRNA.