Adapting Health Technology Assessment agency standards for surrogate outcomes in early stage cancer trials: what needs to happen?

INTRODUCTION

An avalanche of early stage cancer clinical trials is coming. The majority of these solely use surrogate outcomes that have not been validated against a target outcome of interest (e.g. overall survival). Current HTA guidance on surrogate outcome validation are not methodologically or practically conducive to this scenario.

AREAS COVERED

We provide a high-level overview of methods, approaches, and conceptual thinking for making better use of limited evidence within early stage cancer HTA submissions. We outline regulatory and HTA issues and emphasize how evidence transitions from one to another, what major gaps currently exist, and how these may be bridged. We summarize current methodologies and practices, their pros and cons. We outline how complementary measurements strengthen evaluations and address fallacies and biases of conventional statistical methods for surrogate outcomes validation. The value of real-world data to support some of the necessary validity components is discussed. Lastly, we address the importance of the patient voice for better understanding which surrogate outcomes may appropriately inform HTA.

EXPERT OPINION

Conventional surrogate outcome validation represents a fraught and sub-optimal framework for HTA purposes, particularly for early stage cancer. Tools for optimizing use of limited evidence exist. Education of stakeholders is highly needed.

2022 Global patient survey: Reported experience of diagnosis, management, and burden of renal cell carcinomas

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Background: Kidney cancer (renal cell carcinoma, RCC) has shown a sustained increase in its global prevalence thereby presenting increasing burden to health systems, and most of all, to individual patients and their families. Little is known about the variations in the patient experience and best practices among countries. Although individual national surveys have been held, no conclusions could be drawn about country-level variation in patient experience or best practice. Here, we report on the 3rd biennial Global Patient Survey on the diagnosis, management, and burden of Renal Cell Carcinomas conducted by the International Kidney Coalition (IKCC) and involving its Affiliate Organisations worldwide in 15 languages. The aim of the survey was to improve collective understanding and to contribute toward the reduction of the burden of kidney cancer around the world. Methods: A 35-question survey on the diagnosis, management, and burden of RCC was designed by a multi-country steering committee of patient leaders to identify geographic variations in 6 key dimensions: patient education, experience and awareness, access to care and clinical trials, best practices, quality of life, and unmet psychosocial needs. EAU, ESMO, ASCO and NCCN Guidelines committees provided topics of interest to support evidence-based medicine (eg patient perspective on active surveillance, biopsies, etc) . The survey was distributed to patients with kidney cancer and their caregivers in 15 languages, through social media and IKCC’s 49 Affiliate Organizations and/or allied organizations who are not formal affiliates. It was completed online or in paper form between 26 September 2022 and 31 October 2022. At the time of this abstract submission, the survey was still open for completion. Results: We will present the top-line results of the 2022 survey for the very first time. Survey results will be analyzed using cross-tabulations by an independent third-party organization, and multi-variate analysis of predetermined variable will be performed. The full global report will be presented, as well as individual country reports where at least 100 responses were received. Conclusions: The IKCC and its global affiliates will be using the results to ensure that patients’ voices are heard. Actionable points will suggest future projects. Furthermore, individual countries can use their reports to advance their understanding of patient experiences and to drive improvements in care provision locally.

Patient-reported experience of diagnosis, management, and burden of renal cell carcinomas: Results >2,000 patients in 41 countries, with focus on older patients

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Background: Renal cell carcinoma (RCC) is increasing in global prevalence, thereby increasing burden to health systems, and most of all, to individual patients and their families. Little is known about the variations in patient experience and best practices among countries. Here, we report on the second biennial Global Patient Survey on the diagnosis, management, and burden of Renal Cell Carcinomas conducted by the International Kidney Coalition (IKCC) worldwide in 13 languages. The aim of the survey was to improve collective understanding and to contribute toward the reduction of the burden of kidney cancer around the world. Methods: A 35-question survey on the diagnosis, management, and burden of RCC was designed by a multi-country steering committee to identify geographic variations in 6 topics: patient education, experience and awareness, access to care and clinical trials, best practices, quality of life, and unmet psychosocial needs. The survey was distributed to patients with kidney cancer and their caregivers in 13 languages, through IKCC’s 46 Affiliate Organisations and social media from 29 Oct 2020 to 5 Jan 2021. Results: 2,012 responses came from 41 countries. Survey results were analysed using cross-tabulations by an independent third-party organisation. The full global report is publicly available, as well as 7 individual country reports where at least 100 responses were received. 42% reported that the likelihood of surviving their cancer beyond 5 years was not explained Just over half (51%) reported that they were involved as much as they wanted to be in developing their treatment plan. 56% experienced barriers to their treatment 41% indicated that “No one” discussed cancer clinical trials with them 31% were invited to take part in a clinical trial 45% self-reported that they were insufficiently active 50% indicated that they ‘very often’ or ‘always’ experienced disease-related anxiety. 26% ‘very often’ or ‘always’ experienced stress related to financial issues 55% indicated that they ‘very often’ or ‘always’ experienced a fear of recurrence 52% reported having talked to their doctor/healthcare professional about their concerns 48% had been offered a biopsy in the past with only 3% refusing; 47% would be willing to undergo biopsy in the future Patients aged ≤65 experienced more barriers to quality care, understood their disease less well, and experienced a longer time to diagnosis. Conclusions: The IKCC and its global affiliates will be using the results to ensure that patients’ voices are heard. Actionable points will suggest future projects. Individual countries can use their reports to advance their understanding of patient experiences and to improve local care.

Patient-reported experience of diagnosis, management, and burden of renal cell carcinomas: Results from the 2020 Global Patient Survey from 41 countries

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Background: The sustained increased global prevalence of kidney cancer (renal cell carcinoma, RCC) has increased the burden to health systems, and most of all, to individual patients and their families. Although individual national surveys have been held, no conclusions could be drawn about country-level variation in patient experience or best practice. Here, we report on the second biennial Global Patient Survey on the diagnosis, management, and burden of RCC. Conducted by the International Kidney Cancer Coalition (IKCC) and involving its Affiliate Organizations worldwide, the survey aims to improve collective understanding and to contribute toward the reduction of the burden of kidney cancer around the world. Methods: A 35-question survey on the diagnosis, management, and burden of RCC was designed by a multi-country steering committee of patient leaders to identify geographic variations in 6 key dimensions: patient education, experience and awareness, access to care and clinical trials, best practices, quality of life, and unmet psychosocial needs. The survey was distributed in 13 languages to patients with kidney cancer and their caregivers, through IKCC’s 46 Affiliate Organisations and social media. It was completed online or in paper form between 29 Oct 2020 and 5 Jan 2021. Results: 2,012 (1,586 patients, 417 carers, 9 undisclosed) responses were recorded from 41 countries in 13 languages. Survey results were analyzed using cross-tabulations by an independent third-party organization. The full global report will be publicly available, as well as 7 individual country reports where at least 100 responses were received. 52% lacked understanding of subtype at diagnosis. 42% reported that the likelihood of surviving their cancer beyond 5 years was not explained. 51% reported that they were involved as much as they wanted to be in developing their treatment plan. 41% indicated that “No one” discussed cancer clinical trials with them. 31% were invited to take part in a clinical trial. 56% experienced barriers to their treatment. 45% self-reported that they were insufficiently physically active; 15% were completely sedentary. 50% indicated that they ‘very often’ or ‘always’ experienced disease-related anxiety. 55% indicated that they ‘very often’ or ‘always’ experienced a fear of recurrence. 52% reported having talked to their doctor/healthcare professional about their concerns. Conclusions: The IKCC and its global affiliates will use these results to ensure that patient and caregiver voices are heard and acted upon, with ultimate incorporation of these findings by much broader communities into care pathways, clinical practice, or health technology assessments. Furthermore, individual countries can use their reports to advance understanding of patient experiences and to drive improvements in providing care locally.

Patient-reported experience of diagnosis, management, and burden of renal cell carcinomas: Results from a global patient survey in forty-three countries

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Background: The International Kidney Cancer Coalition (IKCC) is a federation of 38 affiliated patient organizations representing 1.2 million patients worldwide that is committed to reduce the global burden of kidney cancer. A large-scale global survey of RCC patients to capture real world experiences (RWE) has never been undertaken. Methods: The 35-question survey was designed to identify geographic variations in patient education, experience and awareness, access to care, best practices, quality of life, involvement in clinical trials and to highlight unmet needs. The survey was conducted online or in paper form in Sept-Oct 2018 by kidney cancer patients and /or their caregivers identified by IKCC’s Affiliate Organizations and through social media in 14 languages. Results: 1,983 responses were recorded from 43 countries. Analysis revealed that at diagnosis, 43% of all respondents had no understanding of their RCC sub-type; patients with clear cell carcinoma (64%) had a notably poorer understanding of their RCC subtype than did patients with rarer RCC subtypes. While 96% of respondents reported psychosocial impacts, surprisingly, only 50% disclosed them to their healthcare team. Of the 70% of patients who were never asked to participate in a clinical trial, 89% responded they would have “fairly likely” done so if asked. RCC patients < 45 years old reported nearly twice as many barriers to treatment as patients > 45 at diagnosis. Females reported longer delays to diagnosis than males. Shared decision making remains aspirational across major cancer centers and community hospitals: globally 29% of all patients reported no involvement in their treatment decision, responding ‘my doctor decided for me’. Conclusions: This exploratory research sheds light on the unmet needs in the RCC patient experience and warrants further analysis. This first-ever global survey serves as a benchmark for longitudinal data collection. RWE indicates opportunities to improve communication about diagnosis, psychosocial impacts, and clinical trials. [Table: see text]

Changing trends in anti-coagulant therapies. Are heparins and oral anti-coagulants challenged?

The conventional management of thrombotic and cardiovascular disorders is based on the use of heparin, oral anticoagulants and aspirin. Despite progress in the sciences, these drugs still remain a challenge and mystery. The development of low molecular weight heparins (LMWHS) and the synthesis of heparinomimetics represent a refined use of heparin. Additional drugs will continue to develop. However, none of these drugs will ever match the polypharmacology of heparin. Aspirin still remains the leading drug in the management of thrombotic and cardiovascular disorders. The newer antiplatelet drugs such as adenosine diphosphate receptor inhibitors, GPIIb/IIIa inhibitors and other specific inhibitors have limited effects and have been tested in patients who have already been treated with aspirin. Warfarin provides a convenient and affordable approach in the long-term outpatient management of thrombotic disorders. The optimized use of these drugs still remains the approach of choice to manage thrombotic disorders. The new anticoagulant targets, such as tissue factor, individual clotting factors, recombinant forms of serpins (antithrombin, heparin co-factor II and tissue factor pathway inhibitors), recombinant activated protein C, thrombomodulin and site specific serine proteases inhibitors complexes have also been developed. There is a major thrust on the development of orally bioavailable anti-Xa and IIa agents, which are slated to replace oral anticoagulants. Both the anti-factor Xa and anti-IIa agents have been developed for oral use and have provided impressive clinical results. However, safety concerns related to liver enzyme elevations and thrombosis rebound have been reported with their use. For these reasons, the US Food and Drug Administration did not approve the orally active antithrombin agent Ximelagatran for several indications. The synthetic pentasaccharide (Fondaparinux) has undergone clinical development. Unexpectedly, Fondaparinux also produced major bleeding problems at minimal dosages. Fondaparinux represents only one of the multiple pharmacologic effects of heparins. Thus, its therapeutic index will be proportionately narrower. The newer antiplatelet drugs have added a new dimension in the management of thrombotic disorders. The favorable clinical outcomes with aspirin and clopidogrel have validated COX-1 and P2Y12 receptors as targets for new drug development. Prasugrel, a novel thienopyridine, Cangrelor and AZD 6140 represent newer P2Y12 antagonists. Cangrelor and AZD 6140 are direct inhibitors, whereas Prasugrel requires metabolic activation. While clinically effective, recent results have prompted a closure of a clinical trial with Prasugrel due to bleeding. The newer anticoagulant and antiplatelet drugs are attractive, however, none of these are expected to replace the conventional drugs in polytherapeutic approaches. Heparins, warfarin and aspirin will continue to play a major role in the management of thrombotic and cardiovascular disorders for years to come.

Up-regulation of inflammatory and thrombotic mediators in lung cancer and their modulation by oral anticoagulantion

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Background: Venous thromboembolic events (VTE) are associated with lung cancer and significantly contributes to the increased mortality in these patients. While the increased prevalence of VTE is fully recognized in lung cancer, its pathogenesis is not fully understood at this time. Even the patients undergoing therapeutic interventions are at high risk to develop VTE. Profiling of surrogate markers of thrombosis and inflammation provides an opportunity to understand the pathogenesis of thrombosis in these patients. Methods: In a prospective, randomized, controlled study patients with inoperable lung cancer (n=100) were randomized to receive chemotherapy, radiation and warfarin (INR 1.5–2.5) or chemotherapy, radiation without warfarin (n=50). Blood samples were drawn prior to and after the second treatment cycle with warfarin. All samples were analyzed for such inflammation markers as the tumor necrosis factor alpha (TNF a), CD 40 ligand (CD 40L), C-reactive protein (CRP), interleukin 1 beta (IL-1β), asymmetric dimethylarginine (ADMA) and nitric oxide (NO). In addition, prothrombin fragment F1.2 (F1.2) and thrombin antithrombin complex (TAT) were also measured. Results: The results are summarized in the following table . All of the surrogate markers of inflammation showed a decreased trend (13–50%) in the warfarin treated group, whereas the non-warfarin treated group exhibited an increase (18–46%) in all markers except CRP and ADMA. The markers of thrombin generation were down regulated in the warfarin treated group. Conclusions: The levels of various inflammatory markers are upregulated in lung cancer suggesting a pathogenic role of this process in lung cancer. Warfarin down regulated the inflammatory and thrombogenic processes in contrast to the non-warfarin treated group. The clinical relevance of these observations require additional analysis.

No significant financial relationships to disclose.

[Table: see text]

Increased levels of inflammatory mediators in lung cancer and their modulation by oral anticoagulant treatment

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Background: Venous thromboembolic events (VTE) are associated with lung cancer and significantly contributes to the increased mortality in these patients. While the increased prevalence of VTE is fully recognized in lung cancer, its pathogenesis is not fully understood. Even the patients undergoing therapeutic interventions are at high risk to develop VTE. These patients provide a unique clinical setting to investigate the pathogenesis of lung cancer associated thrombosis. Methods: In a prospective, randomized, controlled study patients with inoperable lung cancer (n = 100) were randomized to receive chemotherapy, radiation and warfarin (INR 1.5–2.5) or chemotherapy, radiation without warfarin (n = 50). Blood samples were drawn prior to and after the second treatment cycle with warfarin. All samples were analyzed for tumor necrosis factor alpha (TNF α), CD 40 ligand (CD 40L), C-reactive protein (CRP), interleukin 1 beta (IL-1β), asymmetric dimethylarginine (ADMA) and nitric oxide (NO). Results: Summarized in the table given below. All of the surrogate markers of inflammation showed a decreased trend (13–50%) in the warfarin treated group, whereas the non-warfarin treated group exhibited an increase (18–46%) in all markers except CRP and ADMA. Conclusions: The levels of various inflammatory markers are upregulated in lung cancer suggesting a pathogenic role of this process in lung cancer. Warfarin down regulated the inflammatory process in contrast to the non-warfarin treated group. The clinical relevance of these observations require additional analysis.

[Table: see text]

No significant financial relationships to disclose.

Nitric oxide and asymmetric dimethylarginine (ADMA) in malignancy associated thrombosis and their modulation by anticoagulants

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Background: Cancer associated thrombotic complications are primarily due to endothelial dysfunction and upregulation of inflammatory processes. Nitric oxide (NO) represents one of the major endothelial derived vasoactive mediators. Asymmetric dimethylarginine (ADMA) is an endogenous competitive inhibitor of NO synthase which inhibits NO production at pathophysiologic levels. Plasma ADMA levels are upregulated in atherosclerosis, hypertension, end stage renal disease, chronic heart failure and microangiopathy. Methods: To test the hypothesis that endothelial dysfunction in cancer patients may result in increased ADMA levels, plasma samples were retrospectively analyzed from an open label, multidose, active comparator designed study in which all patients (n = 110) were initially treated with low molecular weight heparin, enoxaparin (E) at 1–1.5 mg/kg sc for 5 days and further subdivided into group E which continued to receive E and warfarin (W) group which was given oral anticoagulants for a period of up to 12 weeks. Baseline blood samples (BL), 5 days post E (IPE) and 4–6 week samples from the E and W were analyzed for ADMA and NO levels by ELISA methods. Results: Both the ADMA and NO levels were markedly elevated in cancer patients. The E treated group showed a marked decrease in the ADMA levels which persisted throughout the treatment period. However, in the W converted group the ADMA levels rebounded to an increased level indicating that E differentially regulated ADMA in these patients. The down regulation pattern of NO was similar for both E and W. Conclusions: These results suggest that patients with cancer and thrombosis exhibit simultaneous upregulation of ADMA and NO. While E and W show a differential regulation of ADMA both result in downregulation of NO. The fact that E regulates ADMA is highly suggestive of its role in iNOS regulation which may be involved in the inflammatory response in cancer patients.

[Table: see text]

No significant financial relationships to disclose.

Vascular thrombohemorrhagic disorders: hereditary and acquired

This review has summarized the more important diseases that may be accompanied by or lead to a disorder of hemostasis or thrombosis via alterations of the vasculature. It is to be stressed that the vascular component of hemostasis is often overlooked by clinicians caring for patients with disorders of hemostasis and thrombosis. It should be appreciated that the vasculature is intricately related to the coagulation protein system and to platelets when involved in thrombohemorrhagic diatheses. Although many vascular disorders may lead to hemorrhage or thrombosis, it must be appreciated that often it is impossible to discern between a primary vascular defect/damage and a defect that has been induced by platelet activation/dysfunction or procoagulant abnormalities.

L-asparaginase-provoked seizures as singular expression of central nervous toxicity

Patients treated with L-asparaginase may present with hemorrhagic and thrombotic cerebrovascular events. This syndrome generally occurs after a few weeks of therapy and may occur after L-asparaginase therapy is completed. Complications appear to result from depletion of plasma proteins involved in coagulation and fibrinolysis. Seizures are uncommon symptoms, and are always caused by cerebrovascular events. We report a case of seizure associated with L-asparaginase therapy but no evidence of hemorrhagic or thrombotic cerebrovascular events.

Issues of thrombosis and hemorrhagic events in patients with cancer

It is clear that patients with malignancy, particularly adenocarcinomas, have an increased propensity to thrombosis. It also appears that patients with malignancy and thrombosis are relatively refractory to warfarin therapy and some may not respond ideally to heparin preparations. Occult malignancy in patients with unexplained thrombosis is of concern; however, the incidence varies with the age of the patient approaching 10% in those over 50 years of age. The extent of the evaluation for an underlying occult malignancy should be dictated by clinical judgment. Recurrent unexplained DVT, resistance to warfarin, and thrombosis of unusual sites are the major clues to significantly enhance the suspicion of an occult malignancy. In general, patients with thrombosis and malignancy need not be evaluated for hereditary or acquired hemostasis defects; finding one of these defects is both unlikely and will probably not alter antithrombotic therapy. Hemorrhage in cancer patients is usually due to thrombocytopenia related to chemotherapy (particularly solid tumors) or bone marrow failure (usually leukemias), or disseminated intravascular coagulation (DIC). DIC is usually seen in M-3 and M-4 leukemia or in septic patients with solid tumors. Finally, catheter thrombosis is a common problem in patients with cancer and can be significantly decreased with the routine use of low-dose warfarin therapy.

Useful laboratory tests for studying thrombogenesis in acute cardiac syndromes

We review laboratory tests that evaluate thrombogenesis during acute coronary syndromes. These tests have been found to be valuable research tools in more clearly understanding the pathophysiology of acute coronary syndromes. In particular, we describe tissue factor, tissue factor pathway inhibitor, prothrombin fragment 1.2, thrombin-antithrombin complex, fibrinopeptide A, tissue plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1), t-PA-PAI complex, Bbeta 15-42-related peptides, fibrinogen degradation products, fibrin degradation products, D-dimer, platelet factor 4, beta-thromboglobulin, 5-hydroxytryptamine, thromboxane B2, prostacyclin, endothelin, angiotensin-converting enzyme, soluble thrombomodulin, C1-esterase inhibitor, anaphylotoxins C3a, C4a, and C5a, bradykinin, tumor necrosis factor, leukotriene C4, platelet activating factor, anti-phospholipid antibody, and von Willebrand factor. Some of these tests may prove to be useful in clinical diagnosis and management of acute coronary syndromes. Clinical outcome studies are needed to determine which tests may be cost effective and medically useful.

Response of the neonatal rat cardiomyocyte in culture to energy depletion: effects of cytokines, nitric oxide, and heat shock proteins

Cytokines exert autocrine and paracrine effects on the heart, some of which may be mediated by inducible nitric oxide synthase (i-NOS) expression. We studied the effects of cytokine-mediated NO synthesis on cell injury in the presence of deoxyglucose (DOG) and cyanide (CV)(20 mM DOG and 2 mM CN) for up to 3 hours and during recovery (18 hours). The influence of heat shock protein-70 on the extent of myocyte damage was also assessed. IL-1 beta and gamma-IFN act synergistically to enhance NO synthesis by cardiac myocytes. When these cytokines are present, the rate of ATP depletion after DOG and CN is significantly greater than in their absence. When IL-1 beta and gamma-IFN are added with the NOS inhibitor, L-monomethyl-L-arginine (L-NMMA), or when a cytokine that does not produce NO (TNF-alpha) is present, the rate of ATP depletion is no different from the rate seen with DOG and CN alone. After recovery for 18 hours, myocytes that were exposed to IL-1 beta and gamma-IFN release more lactic dehydrogenase and have significantly lower levels of ATP. L-NMMA decreases lactic dehydrogenase release and maintains ATP at levels similar to metabolically inhibited cells in the absence of these cytokines. Consistent with the decreased recovery in ATP with cells incubated with DOG and CN plus IL-1 beta and gamma-IFN is a decrease in cytochrome oxidase activity. Decreases in cellular ATP correspond to increased levels of heat shock protein-70 measured in myocytes after 18 hours of recovery after metabolic inhibition in the presence of IL-1 beta and gamma-IFN. In contrast, prior induction of heat shock protein-70 reduces the rate of ATP depletion in myocytes treated with DOG and CN and maintains ATP at levels that are significantly higher than those seen in non-heat-shocked cells. Recovery of cells exposed to heat shock is also greater, as seen by decreased lactic dehydrogenase and citrate synthase release. The heat-shocked myocytes contain significantly more glycogen than the cells that were not heat shocked. The increased cellular glycogen is likely responsible for the greater lactate production and slower rates of ATP depletion in the heat-shocked, metabolically inhibited cells. Cell survival under conditions of metabolic inhibition is closely related to cellular ATP preservation.

Free-standing cancer centers: rationale for improving cancer care delivery

Free-standing cancer centers (FSCC) represent a growing trend in cancer care delivery within community practice. The critical components to FSCC are multidisciplinary cancer care, a complete menu of direct care and support services, a commitment to clinical trials and clinical investigation, and a comprehensive program for quality assurance. The advantages of FSCC to the community, to hospital programs, to the practicing surgical, medical, and radiation oncologists, and to the third-party carriers, including health maintenance organizations, are detailed. The development of an FSCC depends on the resolution of issues of (a) competition (between hospitals, hospitals and physicians, therapeutic disciplines, regional comprehensive cancer centers and FSCCs) and (b) concerns about conflict of interest. The ideal model of FSCC may well be represented by the joint venture of community hospital(s) and the community oncologists.

Unsuspected adrenal masses in the neonate: adrenal cortical carcinoma and neuroblastoma. A report of two cases

Masses involving the adrenal in the neonate are most commonly due to hemorrhage. The literature involving the neonatal adrenal reflects this propensity. Although there have been reports of newborns with neuroblastoma [1, 2] and other tumors [3], which are more common in older children, ultrasonographic descriptions of masses involving the adrenal secondary to such tumors are rare [1]. Within a 6-month span we have discovered a clinically unsuspected adrenal carcinoma and adrenal neuroblastoma.

Roussel award for cardiology. The mechanism of nucleotide induced calcium translocation across sarcoplasmic reticulum membranes: evidence for a non-translocated intermediate pool of calcium

Our previous data suggested that, in cardiac muscle sarcoplasmic reticulum fragments, GTP hydrolysis occurs by an alternative enzyme cycle of the Ca2+ ATPase which is insensitive to (Ca2+) and does not involve an acyl phosphate intermediate. Despite this, GTP induces the incorporation of calcium into a membrane pool that is not translocated to the vesicular lumen. The present study suggests that this GTP-induced intermediate calcium pool is identical to a modulable component of the calcium translocation process in that: it has an identical pH sensitivity; the initial incorporation of calcium in response to GTP eliminates the initial rapid burst and lag component of the typical ATP-induced calcium uptake curve when ATP is added during GTP-induced calcium accumulation. Instead, the addition of ATP during GTP-induced calcium accumulation results in the prompt onset of the linear phase of calcium translocation; GTP-induced calcium accumulation directly affects the pH sensitivity of subsequent ATP-induced calcium accumulation. We suggest that the intermediate calcium pool is in series with calcium translocation and is the site of the pH sensitivity observed in calcium flux.

The Effect Of Piracetam In Preventing Recurrent Deep Venous Thrombosis

Piracetam, 2-Oxy-1-pyrrolidine Acetamide is a cyclic derivative of gamma-aminobutyric acid. This agent has recently been shown to have activity in humans as a platelet suppressant. For the prophylaxis of recurrent deep venous thrombosis (RDVT), many clinicians are now resorting to antiplatelet agents, rather than vitamin K antagonist because of the questionable efficacy and severe bleeding associated with these latter agents. The most common antiplatelet agents used for prophylaxis of RDVT are ASA, dipyridamole, and sulfinpyrazone given alone or in various combinations. The purpose of this study was to assess the efficacy of Piracetam as an antiplatelet agent for the prophylaxis of RDVT. Twenty patients with a history of RDVT or with active DVT were entered into the trial; 10 of these were randomized to a combination of ASA (600 mg. BID) + Dipyridamole (50 mg QID) and 10 were randomized to Piracetam at 9.6 gm/day as 2.4 gm QID. Pre-ingestion evaluation included a complete history and physical and complete evaluation of hemostasis including PT, PTT, FDP, PSO4, AT- III, platelet adhesion, platelet aggregation, PF-4, and platelet survival by sizing. Follow-up evaluation was performed at 6 weeks, 3 mo., and 6 mo. All patients demonstrated a laboratory response to antiplatelet therapy as manifest by aggregation and PF-4 studies, all patients on Piracetam and most patients in the other group demonstrated improvement in platelet survival studies. During the six month observation, no patients ingesting Piracetam developed rethrombosis; however, two patients ingesting ASA/Dipyridamole relapsed. These results suggest Piracetam to be equal to and possibly superior to ASA/Dipyridamole in preventing RDVT. In view of this efficacy together with lack of toxicity Piracetam may prove highly useful as a clinically effective antiplatelet agent in the prophylaxis of RDVT.

Phosphorylation of a 100 000 dalton component and its relationship to calcium transport in sarcoplasmic reticulum from rabbit skeletal muscle

Sarcomplasmic reticulum from rabbit fast skeletal muscle contains intrinsic protein kinase activity (ATP:protein phosphotransferase, EC 2.7.1.37) and a substrate. The protein kinase activity was Mg2+ dependent and could also phosphorylate exogenous protein substrates. Autophosphorylation of sarcoplasmic reticulum vesicles was not stimulated by cyclic AMP, neither was it inhibited by the heat-stable protein kinase inhibitor protein. The phosphorylated membranes had the characteristics of a protein with a phosphoester bond. An average of 73 pmol Pi/mg protein were incorporated in 10 min at 30 degrees C. Addition of exogenous cyclic AMP-dependent protein kinase increased the endogenous level of phosphorylation by 25-100%. Sarcoplasmic reticulum membrane phosphorylation, mediated by either endogenous cyclic AMP-independent or exogenous cyclic AMP-dependent protein kinase, occurred on a 100 000 dalton protein and both enzyme activities resulted in enhanced calcium uptake and Ca2+-dependent ATPase (ATP phosphohydrolase, EC 3.6.1.3), in a manner similar to cardiac microsomal preparations. Regulation of Ca2+ transport in skeletal sarcoplasmic reticulum may be mediated by phosphorylation of a 100 000 dalton component of these membranes.

[Bending and torsion stability of healed metatarsus osteotomy after plate osteosynthesis]

72 transversal osteotomies on metatarsus of sheep were stabilized under contact or gap conditions with three different thicknesses of bone plates. After 16 weeks we measured bending or torsion break loading, moment of inertia of bone by transmission methode and calculated moments of bending and torsion strength.

RESULTS

ultimate bending strength on osteotomied bone 100.4 +/- 14.4 N/mm2 under contact, and 77.4 +/- 11.4 N/mm2 under gap condition, torsion bending strength 26.1 +/- 4.9 N/mm2 under contact, and under gap condition 21.5 +/- 4.3 N/mm2. The best results were given by the 2.8 mm plate with the same moment of inertia like the small ASIF plate.