132 GERIATRIC REHABILITATION IN THE COVID-19 ERA: SERVICE INNOVATION AND PATIENT OUTCOMES

Background

Methods

Results

Conclusion

The impact of exogenous nitric oxide during cardiopulmonary bypass for cardiac surgery

OBJECTIVES

Cardiac surgery using cardiopulmonary bypass frequently provokes a systemic inflammatory response syndrome. This can lead to the development of low cardiac output syndrome (LCOS). Both of these can affect morbidity and mortality. This study is a systematic review of the impact of gaseous nitric oxide (gNO), delivered via the cardiopulmonary bypass (CPB) circuit during cardiac surgery, on post-operative outcomes. It aims to summarise the evidence available, to assess the effectiveness of gNO via the CPB circuit on outcomes, and highlight areas of further research needed to develop this hypothesis.

METHODS

A comprehensive search of Pubmed, Embase, Web of Science and the Cochrane Library was performed in May 2020. Only randomised control trials (RCTs) were considered.

RESULTS

Three studies were identified with a total of 274 patients. There was variation in the outcomes measures used across the studies. These studies demonstrate there is evidence that this intervention may contribute towards cardioprotection. Significant reductions in cardiac troponin I (cTnI) levels and lower vasoactive inotrope scores were seen in intervention groups. A high degree of heterogeneity between the studies exists. Meta-analysis of the duration of mechanical ventilation, length of ICU stay and length of hospital stay showed no significant differences.

CONCLUSION

This systematic review explored the findings of three pilot RCTs. Overall the hypothesis that NO delivered via the CPB circuit can provide cardioprotection has been supported by this study. There remains a significant gap in the evidence, further high-quality research is required in both the adult and paediatric populations.

Mid-Upper Arm Circumference (MUAC) shows strong geographical variations in children with edema: results from 2277 surveys in 55 countries

BACKGROUND

Severe acute malnutrition (SAM) is defined by a mid-upper arm circumference (MUAC) less than 115 mm or a weight-for-height z-score (WHZ) less than - 3 but also by the presence of bilateral pitting edema, also known as kwashiorkor or edematous malnutrition. Although edematous malnutrition is a life threatening condition, it has not been prioritized in recent research and has been neglected in global health initiatives.

METHODS

Two thousand two hundred and seventy-seven survey datasets were collected, and the age, sex, weight, height, MUAC and the presence or absence of edema were analyzed for more than 1.7 million children of 6-59 months from 55 countries, covering the period of 1992 to 2015.

RESULTS

During the last 10 years, the prevalence of nutritional edema was estimated at less than 1% in most of the countries where data were available. Some countries in Central and South Africa, as well as Haiti in the Caribbean, reported higher prevalence, and Yemen, Zimbabwe and the Democratic Republic of Congo reported prevalence between 1 and 2%. Surveys from a significant number of countries in Africa indicated that more than a third of SAM cases defined by MUAC < 115 mm had edema, including Malawi, Rwanda, Zambia, Togo and Cameroon. Children with edema were consistently shown across various analyses to have a significantly lower median MUAC than children without edema. However, the MUAC distribution had a large spread, with many children with edema having a MUAC > 115 mm, and this varied widely between countries, with median MUAC in edematous children ranging from 102 mm (Mali) to 162 mm (Sri Lanka). The proportion of SAM children with edema was found to be higher for older children.

CONCLUSIONS

This study provides the most recent geographical distribution of nutritional edema and demonstrates that edema is a common manifestation of SAM, mainly occurring in Central Africa. The associated nutritional status, as assessed by MUAC, shows strong variation among children with edema. A more systematic and standardized system is required to collect data on edema in order to facilitate prevention, screening, referral and treatment of edematous malnutrition.

Abstract P1-16-03: Quantitative versus semi-quantitative assessments of radiation-induced pulmonary fibrosis post adjuvant breast radiotherapy

Objective

To evaluate the quantitative versus semi-quantitative assessments of radiation induced pulmonary fibrosis (RIPF) post adjuvant breast radiotherapy (RT).

Methods

High resolution computed tomography (HRCT) assessed lung physical density changes (CTD) and physician identified HRCT visual grading scores (CTS) were analysed at the minimum of 12 months post RT at one institution. The treated side in-portal lung regions for CTD and CTS assessments were: central-axis (CA) + regions 5cm superior & inferior to CA and the corresponding mid anterolateral region respectively. Respiratory motion was accounted for by subtracting the untreated side lung density from the treated side. Mean lung densities correspond to each voxels were automatically calculated by Pinnacle software (Phillips, Eindhoven, The-Netherlands). Grading of CTS was according to the RTOG/EORTC (grade 0, 1, 2, and 3 defined as none, slight, patchy, and dense HRCT appearance respectively) and analysed by a radiologist (JL) and re-checked a radiation oncologist (PG).

Results

Total numbers of 403 patients were analysed. A substantial association was verified between CTD and CTS assessment. An increase of ∼0.01 g/ml (95% CI 0.003-0.02) in CTD with each CTS score increase of 1 was observed (Table-1a). The RIPF can be categorised quantitatively into three groups of CTS 0 vs. 1-2 vs. 3 based on the mean CTD (Table-1b).

Table-1a. Correlation between CTD and CTS method. Table-1b. Grouping of CTS based on CTD methodTable-1a. Correlation between CTD and CTS methodCTSTreated side mean CTD - LeftTreated side mean CTD - RightMean Total00.055 (119)-0.011 (136)0.020 (255)10.065 (60)0.005 (56)0.036 (116)20.083 (15)0.012 (13)0.050 (28)30.108 (4)00.108 (4)Total0.061 (198)-0.005 (205)0.028 (403)Table-1b. Grouping of CTS based on CTD methodCTSTreated side mean CTD - LeftTreated side mean CTD - RightMean Total95% Confidence interval00.055 (119)-0.011 (136)0.020 (255)0.012-0.0271-20.069 (75)0.006 (69)0.039 (144)0.029-0.04830.108 (4)00.108 (4)0.079-0.137

A cut off CTD of 0.089 g/ml exemplified the best compromise between sensitivity (100%) and specificity (88.2%) for dense HRCT appearance. However, there was no good compromise of CTD cut off for slight and patchy HRCT score possibly due to intra observer variation and the scale of the CTD measure (small increase in CTD may not be detected visually by the observer). Multivariable analysis revealed increasing age, current smoker, V20 ≥ 10% (the volume of lung that was covered by the 20Gy isodose line), central lung distance ≥ 2cm (the distance between posterior RT tangents and the chest wall), combined endocrine & chemotherapy, and treated side mean CTD to be significantly associated with development of grade ≥1 RIPF.

Conclusions

There was a good correlation between quantitative (CTD) and semi-quantitative (CTS) assessment of RIPF post adjuvant breast RT. The CTD method could be advantageous for both routine clinical practice and future clinical trials that require more detailed quantification of dense RIPF.

Citation Format: Pramana A, Browne L, Cox H, Saba A, Pham K, Trakis S, Crawford K, Hall M, Batchelor N, Lim J, Graham P. Quantitative versus semi-quantitative assessments of radiation-induced pulmonary fibrosis post adjuvant breast radiotherapy. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-16-03.

Prediction of outcome of early ER+ breast cancer is improved using a biomarker panel, which includes Ki-67 and p53

Background:

The aim of this study is to determine whether immunohistochemical (IHC) assessment of Ki67 and p53 improves prognostication of oestrogen receptor-positive (ER+) breast cancer after breast-conserving therapy (BCT). In all, 498 patients with invasive breast cancer from a randomised trial of BCT with or without tumour bed radiation boost were assessed using IHC.

Methods:

The ER+ tumours were classified as ‘luminal A’ (LA): ER+ and/or PR+, Ki-67 low, p53−, HER2− or ‘luminal B’ (LB): ER+ and/or PR+and/or Ki-67 high and/or p53+ and/or HER2+. Kaplan–Meier and Cox proportional hazards methodology were used to ascertain relationships to ispilateral breast tumour recurrence (IBTR), locoregional recurrence (LRR), distant metastasis-free survival (DMFS) and breast cancer-specific survival (BCSS).

Results:

In all, 73 patients previously LA were re-classified as LB: a greater than four-fold increase (4.6–19.3%) compared with ER, PR, HER2 alone. In multivariate analysis, the LB signature independently predicted LRR (hazard ratio (HR) 3.612, 95% CI 1.555–8.340, P=0.003), DMFS (HR 3.023, 95% CI 1.501–6.087, P=0.002) and BCSS (HR 3.617, 95% CI 1.629–8.031, P=0.002) but not IBTR.

Conclusion:

The prognostic evaluation of ER+ breast cancer is improved using a marker panel, which includes Ki-67 and p53. This may help better define a group of poor prognosis ER+ patients with a greater probability of failure with endocrine therapy.

Impacts of unregulated harvesting on a recovering stock of native oysters (Ostrea edulis)

In Strangford Lough, Northern Ireland stocks of Ostrea edulis collapsed in the 1890s and the species was rarely recorded again until 1998 when the wild stock was estimated to be 100,000. The stock increased to 1.2 million in 2003 but declined to 650,000 by 2005. In 2007 the stock exceeded 1 million. The initial recovery of wild stocks is attributed to the combined effects of spawning commercial O. edulis stocks of and larval retention due to local hydrography. The stock decline between 2003 and 2005 is attributed to unregulated harvesting. Significant differences in abundances between sites over this period may be explained by the exploitation of more-readily accessible sites initially and of less accessible sites later. Oysters at sites where there was minimal exploitation probably contributed to widespread recruitment in 2007. Sustainable management of recovering native oyster stocks in Strangford Lough and elsewhere and will be impossible without appropriate legislation and enforcement.

Women from non-English speaking backgrounds living in Australia present with later stage breast cancer: A population study

17043

Background: Ethnicity may influence both the incidence and prognosis of breast cancer. We have conducted an analysis to determine if women from non-English speaking backgrounds (NESB) living in New South Wales (NSW), Australia, present with later stage breast cancer compared to women from English speaking backgrounds (ESB); and to determine whether there is an impact on their survival. Methods: Data from the NSW Cancer Registry (1980 to 2004) was used to identify women with their first presentation of breast cancer. Stage of breast cancer was classified as early (insitu or localized) versus late (regional nodal or distant metastatic spread) according to registry definitions. Country of birth was used as a surrogate for language status. Stage at diagnosis was compared between ESB versus NESB women. Logistic regression was used to determine the odds of late stage disease and Cox regression to determine survival outcomes Results: 60,676 of 75,583 cases were considered suitable for analysis. Of these 16.64% were NESB. Accounting for potential confounding variables, NESB women were more likely to have late stage disease than ESB women (OR= 1.12; 95% CI, 1.07 to 1.17). Analysis by geographical region of birth revealed women born in Middle Eastern region were most likely to have late stage disease at presentation (OR 1.41; 95% CI, 1.25 to 1.60). In multivariable analysis of all-cause mortality NESB women had a superior overall survival (HR 0.90; 95% CI 0.87 to 0.94) compared to ESB women, however, there was no difference in breast cancer specific survival between these groups by univariate analysis (logrank p=0.46). Conclusions: In New South Wales, Australia, NESB women have a delayed presentation with breast cancer as indicted by more advanced stage. However, stage-adjusted, breast cancer specific survival in NESB women is similar to the ESB women. Further studies are required to determine the reasons for delayed detection for NESB women.

No significant financial relationships to disclose.

Effectiveness of standard UV depuration at inactivating Cryptosporidium parvum recovered from spiked Pacific oysters (Crassostrea gigas)

When filter-feeding shellfish are consumed raw, because of their ability to concentrate and store waterborne pathogens, they are being increasingly associated with human gastroenteritis and have become recognized as important pathogen vectors. In the shellfish industry, UV depuration procedures are mandatory to reduce pathogen levels prior to human consumption. However, these guidelines are based around more susceptible fecal coliforms and Salmonella spp. and do not consider Cryptosporidium spp., which have significant resistance to environmental stresses. Thus, there is an urgent need to evaluate the efficiency of standard UV depuration against the survival of Cryptosporidium recovered from shellfish. Our study found that in industrial-scale shellfish depuration treatment tanks, standard UV treatment resulted in a 13-fold inactivation of recovered, viable C. parvum oocysts from spiked (1 x 10(6) oocysts liter (-1)) Pacific oysters. Depuration at half power also significantly reduced (P < 0.05; ninefold) the number of viable oocysts recovered from oysters. While UV treatment resulted in significant reductions of recovered viable oocysts, low numbers of viable oocysts were still recovered from oysters after depuration, making their consumption when raw a public health risk. Our study highlights the need for increased periodic monitoring programs for shellfish harvesting sites, improved depuration procedures, and revised microbial quality control parameters, including Cryptosporidium assessment, to minimize the risk of cryptosporidiosis.

Supraclavicular radiotherapy must be limited laterally by the coracoid to avoid significant adjuvant breast nodal radiotherapy lymphoedema risk

This cross-sectional study aimed to investigate the effect of supraclavicular fossa (SCF) radiotherapy volumes as well as patient characteristics and nodal pathology on the development of lymphoedema. Ninety-one women who had received SCF nodal radiotherapy after axillary dissection were evaluated. Lymphoedema was defined by two measurements: limb volume difference 200 mL, or circumference difference 10 cm proximal or distal to the olecranon>2 cm. On univariate analysis, the addition of axillary to SCF radiotherapy, increasing width of the SCF field, increasing age, presence of extracapsular extension of nodal involvement and use of hormone treatment was associated with lymphoedema by either one or both definitions. For both definitions of lymphoedema, on multivariate analysis, increasing nodal radiotherapy volume remained significant (P=0.02 to 0.007), as did increased age (P=0.05 to 0.001). We conclude that conventionally fractionated SCF radiotherapy limited laterally by the coracoid process has a lymphoedema risk similar to that expected from axillary dissection alone and a lower risk than wider SCF fields with or without an axillary boost.

Concurrent end-phase boost high-dose radiation therapy for non-small-cell lung cancer with or without cisplatin chemotherapy

The aim of this study was to audit the results of a high-dose, combined-modality prospective protocol for non-small-cell lung cancer in terms of survival, disease-specific survival and toxicity. One hundred and twenty-one patients with non-small-cell lung cancer were treated with a concurrent, end-phase, boost, high-dose radiotherapy protocol with 65 Gy in 35 fractions for more than 5 weeks. Sixty-six patients received radiotherapy alone (group 1), 29 received concurrent chemoradiation (group 2) and 26 received neoadjuvant and concurrent chemotherapy (group 3). Thirty-four patients had stage I disease, six had stage II and 81 had stage III. Overall median survival was 23 months: 75% at 1 year and 23% at 5 years. Median survivals for patients with stage I and stages II and III disease were 43 and 19 months, respectively. For stages II and III patients by groups 1-3, median survivals were 18, 25 and 18 months, respectively, and 2-year survivals were 36, 52 and 38%, respectively. Toxicity was acceptable. Overall, 9% had symptomatic pneumonitis and 7% had grades 3 and 4 oesophagitis. For those who had the mediastinum included in the volume, grade > or = 3 oesophagitis occurred in 0, 11 and 22% (n = 110, P = 0.001), respectively, for treatment groups 1-3. Overall treatment-related mortality was 3%, consisting of two septic deaths, one pneumonitis and possibly one late cardiac event, all occurring in patients who had chemotherapy (7% of 55 patients). Treatment-related mortality declined over the study period. Accelerated radiotherapy was well tolerated, with only moderate increased acute toxicity when combined with concurrent platinum chemotherapy. Toxicity was enhanced by induction chemotherapy. Overall survival outcomes were excellent for this condition. Continued use of this radiotherapy schedule is recommended as the platform for assessment of other chemotherapy schedules.

A Pilot Randomised Comparison of Dexamethasone 96mg vs 16mg per day for Malignant Spinal-cord Compression Treated by Radiotherapy: TROG 01.05 Superdex Study

AIM

To test the viability of a full-scale randomised comparison of two steroid doses given with radiotherapy for malignant spinal-cord compression (MSCC), to test Internet randomisation and to compare different functional outcome measures.

MATERIALS AND METHODS

A log of screened patients at eight recruiting centres was maintained. Patients were randomised via the Superdex website to either 96 mg or 16 mg daily of dexamethasone. Radiotherapy treatment was 30 Gy in 10 fractions. Outcomes assessed used ambulation, Barthel Index ambulation, Functional Independence Measure (FIM) ambulation and Functional Improvement Score (FIS) at 1 month.

RESULTS

One hundred and thirty-one patients were screened. Ninety-three (71%) were ineligible, 65% of these were because duration of prior steroid use was greater than 12 h, failure to meet strict definition of magnetic resonance imaging, defined MSCC, multi-level disease or previous spinal-cord compression treatment. Twenty of the 38 eligible patients were randomised, including seven outside standard office hours. There was a high rate of serious adverse events (n = 9), but only one was considered likely to be related to study medication. At baseline, 75% were ambulant, 70% had FIM ambulation scores greater than 5 and 50% had Barthel Index ambulation scores greater than 2. At day 28, including all randomised patients (by scoring four dead patients as non-ambulant), ambulation scores by the various definitions were 60%, 45% and 40%, respectively. For the 16 patients evaluable at day 28, the mean FIS was -1.4. Median survival was 69 days and 1-year survival 13%.

CONCLUSION

Web randomisation was successful; however, the high ineligibility rate precludes a full-scale dexamethasone dose trial in Australia. Choice of measure of ambulation has potentially significant effects on outcomes and implications for the design of any future MSCC trials. Referral delays are of concern.

July 2004: 40-year-old man with headaches and dyspnea

A 40-year-old man had a 6-week history of severe frontal headaches and dry cough. Chest x-ray showed hilar adenopathy with bilateral parenchymal infiltrates. A diagnosis of atypical pneumonia was made. Four weeks later he was admitted with persistent headache. Infectious screen was negative. Brain MR post contrast, revealed cerebellar enhancement and swelling with moderate tonsillar herniation; findings which precluded the performance of a lumbar puncture. High resolution CT thorax confirmed hilar abnormalities; shown by microscopy to represent non caseating granulomata. A presumptive diagnosis of sarcoidosis was reached. Despite an initial symptomatic improvement his headache persisted. Repeat MRI, eleven days after admission, showed reduced cerebellar enhancement and swelling with no change in the degree of tonsillar herniation. He deteriorated acutely and died two weeks after admission. Autopsy revealed cerebral oedema with tonsillar herniation secondary to cryptococcal meningitis variety neoformans. There was no evidence of neurosarcoid. Active and inactive sarcoid was identified in the lungs and hilar nodes with no evidence of systemic sarcoid. Focal evidence of cryptococcal pneumonitis was present in the lung as a necrotic focus. A strong index of clinical suspicion is necessary to diagnose the rare association of cryptococcus complicating sarcoidosis.

Comparing lecture and e-learning as pedagogies for new and experienced professionals in dentistry

OBJECTIVE

To evaluate the relative effectiveness of e-learning versus lecture learning in VDPs and trainers.

DESIGN

Experimental comparison of two groups' learning retention.

SETTING

VDPs and trainers from two regions were assessed by independent researchers.

METHOD

One region's VDPs and trainers received e-learning; another's received a traditional one hour lecture. Retention and understanding were tested and compared. Personal preference was assessed in group interviews.

RESULTS

Significantly greater retention for the trainees occurred from lecturing rather than e-learning, and for the trainers e-learning was significantly more successful than lecturing.

CONCLUSIONS

Small numbers in this study preclude wide generalisation. However, the results point to the benefits of face-to-face interaction for inexperienced staff, and the benefits of the speed and manageability of e-learning for busy, more experienced staff. The need for a discussion facility to be incorporated into ICT innovations to CPD (via, for example, online 'chatrooms') is also highlighted, with the potential of greatly enhancing e-learning efficacy.

Intracranial giant cell arteritis with fatal middle cerebral artery territory infarct

A 37 year-old man who developed a fatal middle cerebral territory infarct was found at autopsy, to have widespread granulomatous angiitis involving meningeal and intracranial--extracerebral vessels but not intracerebral vessels or other extra-cranial vessels. The findings are unique and overlap with those of granulomatous angiitis of the nervous system (GANS) and classic giant cell arteritis (GCA). A possible precipitant for this devastating illness was a recent Chlamydia infection. The salient clinical and pathologic differences between GANS and GCA of the nervous system are discussed.

Inhalation aromatherapy during radiotherapy: results of a placebo-controlled double-blind randomized trial

PURPOSE

To determine whether the inhalation of aromatherapy during radiotherapy reduces anxiety.

PATIENTS AND METHODS

Three hundred thirteen patients undergoing radiotherapy were randomly assigned to receive either carrier oil with fractionated oils, carrier oil only, or pure essential oils of lavender, bergamot, and cedarwood administered by inhalation concurrently with radiation treatment. Patients underwent assessment by the Hospital Anxiety and Depression Scale (HADS) and the Somatic and Psychological Health Report (SPHERE) at baseline and at treatment completion.

RESULTS

There were no significant differences in HADS depression or SPHERE scores between the randomly assigned groups. However, HADS anxiety scores were significantly lower at treatment completion in the carrier oil only group compared with either of the fragrant arms (P =.04).

CONCLUSION

Aromatherapy, as administered in this study, is not beneficial.

Functional properties of transfected human DMT1 iron transporter

Recently, mutation of the DMT1 gene has been discovered to cause ineffective intestinal iron uptake and abnormal body iron metabolism in the anemic Belgrade rat and mk mouse. DMT1 transports first-series transition metals, but only iron turns on an inward proton current. The process of iron transport was studied by transfection of human DMT1 into the COS-7 cell line. Native and epitope-tagged human DMT1 led to increased iron uptake. The human gene with the Belgrade rat mutation was found to have one-fifth of the activity of the wild-type protein. The pH optimum of human DMT1 iron uptake was 6.75, which is equivalent to the pH of the duodenal brush border. The transporter demonstrates uptake without saturation from 0 to 50 microM iron, recapitulating earlier studies of isolated intestinal enterocytes. Diethylpyrocarbonate inhibition of iron uptake in DMT1-transfected cells suggests a functional role for histidine residues. Finally, a model is presented that incorporates the selectivity of the DMT1 transporter for transition metals and a potential role for the inward proton current.

Armrest versus vacuum bag immobilization in the treatment of breast cancer by radiation therapy: a randomized comparison

Thirty patients in randomized sequence were simulated in both an arm-rest and a vacuum bag immobilization device and also randomized to treatment in one of the two devices. Overall patient comfort significantly favoured the use of the arm-rest, although both were acceptable. Lung exposed in the tangential beams was less in the vacuum bag device. Supraclavicular skin folding was greater in the vacuum bag, but this is probably related to the angle of arm abduction. Treatment times and stability of the setups were not significantly different. This is a small study piloting a technical comparison and the findings require confirmation in a larger sample.

Mental health home visits for the elderly

TOPIC

The nurse's role in providing mental health services to the elderly.

SOURCE

The Mental Health Interventions Program.

GOAL

To provide a viable model for providing these services.

CONCLUSION

Nurses have the skills necessary to ensure that the elderly are recipients of quality mental health care.

The utility of latex agglutination assays in the diagnosis of pediatric viral gastroenteritis

To design a rapid and efficient protocol for processing pediatric stool specimens, the authors used 434 specimens to evaluate two commercial latex assays to detect rotavirus (Meritec-Rotavirus and Rotalex) and one to detect adenovirus (Adenolex). Rotavirus latex assay results were compared with electron microscopic examination and adenovirus latex assay results with virus culture. Ninety-two specimens (21%) were positive for rotavirus and 28 (6.5%) for adenovirus; 5 (1%) had both viruses. The sensitivity, specificity, positive predictive values, and negative predictive values for the three assays were, respectively, as follows: Meritec-Rotavirus (97%, 99%, 97%, 99%), Rotalex (91%, 99%, 94%, 98%), and Adenolex (46%, 99%, 77%, 97%). For primary rotavirus screening, the Meritec-Rotavirus and Rotalex latex assays offer a good alternative to electron microscopic examination. For primary adenovirus screening, the low sensitivity of the Adenolex latex assay precludes its use as a routine screen. Its excellent specificity, however, makes it a useful tool for culture confirmation.

Characterization of an antigenically related family of cell-type specific proteins implicated in slug migration in Dictyostelium discoideum

The monoclonal antibody MUD50 recognizes a group of developmentally regulated proteins, which are almost exclusively expressed by prespore cells in developing aggregates of Dictyostelium discoideum. Some of these antigens are integrally associated with the cell membrane, as assessed by physical and detergent-fractionation procedures. The MUD50-reactive proteins are glycosylated and some are phosphorylated. Post-translational modification is the common antigenic feature that is recognized by the MUD50 antibody in these cell-type-specific proteins. A glycosylation-defective mutant, DL118, (modB) does not express the MUD50 epitope, but does express the MUD52 epitope, which is found on a different group of glycoproteins. Therefore, we conclude that MUD50 recognizes a particular carbohydrate epitope on a restricted group of proteins. These proteins are structurally diverse, but are apparently involved in the maintenance of structure and movement of the multicellular D. discoideum slug.

Binding of [14,15-3H]14,15-dihydroforskolin to rat liver membranes: comparison with the stimulatory effect of forskolin on adenylate cyclase

The binding of [14,15-3H]14,15-dihydroforskolin ([3H]DHF) to rat liver membranes has been further characterized and was compared with the stimulatory effect of forskolin on adenylate cyclase. The binding equilibrium dissociation constant (KD) for 14,15-dihydroforskolin obtained in inhibition experiments was 0.6 microM, with a maximal binding capacity (Bmax) of 114 pmol/mg protein. A similar KD value (0.5 microM) was derived from kinetics studies that revealed very rapid association and dissociation reactions. For structure-activity relationship studies several forskolin derivatives were synthesized and tested for their ability to inhibit [3H]DHF binding and increase adenylate cyclase activity. Among the tested compounds, forskolin itself was the most potent agonist (K1 = 0.2 microM). Further modification of the molecule in position 7 and (or) 1 decreased or abolished its agonist properties in both adenylate cyclase and binding studies. [3H]DHF binding was not affected by several nucleotides, carbohydrates, lectins, and hormone receptor agonists including isoproterenol, glucagon, and adenosine, but the steroids 17-beta-estradiol, progesterone, and testosterone showed slight inhibitory effects at unphysiologically high concentrations. [3H]DHF binding and forskolin-stimulated adenylate cyclase were sensitive to heat and N-ethylmaleimide treatment. Forskolin protected adenylate cyclase against inactivation by heat but not by N-ethylmaleimide. Preincubation of the membrane with trypsin decreased [3H]DHF binding. The results presented in this study demonstrate that the binding sites identified with [3H]DHF have a high specificity for forskolin and provide evidence that these binding sites are involved in the stimulation of adenylate cyclase by forskolin.