Expression of fibrinogen receptors during activation and subsequent desensitization of human platelets by epinephrine

Epinephrine causes platelet aggregation and secretion by interacting with alpha 2-adrenergic receptors on the platelet surface. Platelet aggregation requires the binding of fibrinogen to a specific receptor on the membrane glycoprotein IIb-IIIa complex. Although the IIb-IIIa complex is identifiable on the surface of resting platelets, the fibrinogen receptor is expressed only after platelet activation. The current studies were designed to examine the effect of occupancy of platelet alpha 2-adrenergic receptors by epinephrine on the expression of fibrinogen receptors and on the aggregation of platelets. The ability of epinephrine to induce the expression of fibrinogen receptors was studied under two different conditions: acute stimulation (less than 1 min) and prolonged stimulation (50 to 90 min), the latter of which is associated with a reduction or "desensitization" of the platelet aggregation response. Expression of the fibrinogen receptor was monitored with 125I-fibrinogen as well as with 125I-PAC-1 (PAC-1), a monoclonal antibody that binds to the glycoprotein IIb-IIIa complex only after platelets are activated. Epinephrine caused an immediate increase in PAC-1 and fibrinogen binding that was dependent on occupancy of the alpha 2-receptor by epinephrine and on the presence of extracellular free Ca (KCa = 30 mumol/L). By itself, 1 mmol/L Mg was unable to support induction of the fibrinogen receptor by epinephrine. However, it did decrease the Ca requirement by about two orders of magnitude. Prolonged stimulation of unstirred platelets by epinephrine led to a 70% decrease in the aggregation response when the platelets were subsequently stirred. Despite their decreased aggregation response, desensitized platelets bound PAC-1 and fibrinogen normally, indicating that the loss of aggregation was not due simply to a decrease in fibrinogen receptor expression. Although desensitization was not affected by pretreatment of the platelets with aspirin, it was partially prevented when extracellular Ca was chelated by EDTA during the long incubation with epinephrine. These studies demonstrate that once platelet alpha 2-adrenergic receptors are occupied by epinephrine, extracellular Ca is involved in initiating the aggregation response by supporting the induction of the fibrinogen receptor and the binding of fibrinogen. Furthermore. Ca-dependent reactions subsequent to fibrinogen binding may be necessary for maximal platelet aggregation and are impaired when platelets become desensitized to epinephrine.     

Recombinant human interleukin-11 stimulates multilineage hematopoietic recovery in mice after a myelosuppressive regimen of sublethal irradiation and carboplatin

Interleukin-11 (IL-11) is a novel multifunctional hematopoietic cytokine capable of stimulating cells of the myeloid, lymphoid, erythroid, and megakaryocytic lineages in vitro. We have tested the pleiotropic properties of this cytokine on the hematopoietic recovery of mice after a combined regimen of sublethal irradiation and carboplatin administration. This regimen results in severe myelosuppression, characterized by a prolonged period of thrombocytopenia and severe anemia. Administration of recombinant human IL-11 (rhIL-11; 250 micrograms/kg/d) had multilineage effects on bone marrow and spleen hematopoietic activity, increasing the number of megakaryocyte, erythroid, granulocyte, and macrophage progenitors compared with the vehicle-treated controls. This was reflected in the peripheral circulation by a reduction of both the platelet and hematocrit nadirs and a significantly reduced period of thrombocytopenia and anemia in the rhIL-11-treated mice. The results from this study support the broad spectrum of biologic activities that have been attributed to rhIL-11 in vitro and suggest that this cytokine may be an effective agent in the treatment of myelosuppression associated with cancer chemotherapy and bone marrow transplantation.     

Distinct Neuropsychological Mechanisms May Explain Delayed- Versus Rapid-Onset Antidepressant Efficacy

The biochemical targets for antidepressants are relatively well established, but we lack a clear understanding of how actions at these proteins translate to clinical benefits. This study used a novel rodent assay to investigate how different antidepressant drugs act to modify affective biases that have been implicated in depression. In this bowl-digging task, rats encounter two equal value learning experiences on separate days (one during an affective manipulation and the other during control conditions). This induces an affective bias that is quantified using a preference test in which both digging substrates are presented together and the individual rats’ choices recorded. The assay can be used to measure affective biases associated with learning (when the treatment is given at the time of the experience) or examine the modification of previously acquired biases (when the treatment is administered before the preference test). The rapid-onset antidepressant ketamine, but not the delayed-onset antidepressant, venlafaxine, attenuated the previously acquired FG7142-induced negative bias following systemic administration. Venlafaxine but not ketamine induced a positive bias when administered before learning. We then used local drug infusions and excitotoxic lesions to localize the effects of ketamine to the medial prefrontal cortex and venlafaxine to the amygdala. Using a modified protocol we also showed that positive and negative biases amplified further when the numbers of substrate–reinforcer associations are increased. We propose that this pattern of results could explain the delayed onset of action of venlafaxine and the rapid onset of action but lack of long-term efficacy seen with ketamine.     

Interferon gamma release assay in the diagnosis of tuberculous mastitis

Tuberculous mastitis is rare, especially in Western countries. We describe a case where the interferon gamma release assay blood test led to diagnosis and successful treatment of the disease.     

Development of large numbers of mast cells at sites of idiopathic chronic dermatitis in genetically mast cell-deficient WBB6F1-W/Wv mice

The normal skin and other tissues of adult mast cell-deficient WBB6F1- W/Wv or WCB6F1-Sl/Sld mice contain less than 1.0% the number of mast cells present in the corresponding tissues of the congenic normal (+/+) mice. As a result, genetically mast cell-deficient WBB6F1-W/Wv or WCB6F1-Sl/Sld mice are widely used for studies of mast cell differentiation and function. We found that mast cells developed at sites of idiopathic chronic dermatitis in WBB6F1-W/Wv mice and that the number of mast cells present in the skin of WBB6F1-W/Wv mice was proportional to the severity of the dermatitis (in ear skin, there were 33 +/- 4 mast cells/mm2 of dermis at sites of severe dermatitis v 9 +/- 3 at sites of mild dermatitis, 0.8 +/- 0.3 in skin without dermatitis, and 100 +/- 7 in the normal skin of congenic WBB6F1-+/+ mice; in back skin, the corresponding values were 2.0 +/- 0.6, 1.1 +/- 0.9, 0.025 +/- 0.025, and 26.2 +/- 3.2). The development of mast cells was a local, not systemic, consequence of the dermatitis. Thus, WBB6F1-W/Wv mice with severe dermatitis lacked mast cells in skin not showing signs of dermatitis and also in the peritoneal cavity, stomach, cecum, and tongue. Idiopathic chronic dermatitis was not associated with the local development of mast cells in WCB6F1-Sl/Sld mice, a mutant whose mast cell deficiency is due to a mechanism distinct from that of WBB6F1-W/Wv mice. These findings may have implications for understanding the nature of the mast cell deficiency in WBB6F1-W/Wv and WCB6F1-Sl/Sld mice and for the use of these mutants to analyze mast cell differentiation and function.     

Ebola Policies That Hinder Epidemic Response by Limiting Scientific Discourse

There is an unprecedented epidemic of Ebola virus disease (EVD) in west Africa. There has been a strong response from dedicated health professionals. However, there have also been irrational and fear-based responses that have contributed to misallocation of resources, stigma, and deincentivizing volunteers to combat Ebola at its source. Recently, the State of Louisiana Department of Health and Hospitals issued a ban on those coming from affected countries wishing to attend the annual meetings of American Society of Tropical Medicine and Hygiene and the American Public Health Association, both of which were held in New Orleans. We argue against such policies, question evidence and motivations, and discuss their practical and ethical implications in hampering effective responses to EVD by the scientific community. We aim to shed light on this issue and its implications for the future of public health interventions, reflect on the responsibility of health providers and professional societies as advocates for patients and the public health, and call for health professionals and societies to work to challenge inappropriate political responses to public health crises.On October 28, 2014, 5 days before the annual meeting of the American Society of Tropical Medicine and Hygiene (ASTMH) in New Orleans, the Louisiana Department of Health and Hospitals (DOHH) in conjunction with the Governor''s Office for Homeland Security and Emergency Preparedness announced to all ASTMH attendees that “individuals who traveled to and returned from the countries of Sierra Leone, Liberia or Guinea in the past 21 days, or have had contact with a known EVD [Ebola virus disease] patient in that time period, should NOT travel to New Orleans to attend the conference. Given that conference participants with a travel and exposure history for EVD are recommended not to participate in large group settings (such as this conference) or to utilize public transport, we see no utility in you traveling to New Orleans to simply be confined to your room.” Furthermore, the letter stated that “from a medical perspective, asymptomatic individuals are not at risk of exposing others; however, the State is committed to preventing any unnecessary exposure of Ebola to the general public. In Louisiana, we love to welcome visitors, but we must balance that hospitality with the protection of Louisiana residents and other visitors.”¹While acknowledging recommendations of the Centers for Disease Control and Prevention (CDC) that asymptomatic individuals are not a risk to others, the statement went beyond the CDC guidelines and implied a potential threat from conference attendees, even those without exposure to EVD, based solely on travel history to countries affected by the epidemic. We believe the DOHH should appreciate the negative ramifications of unscientifically based travel bans and quarantine policies and rather, follow evidence-based guidelines to protect the public and avoid legitimizing irrational responses caused by fear.Ironically, the ASTMH is the pre-eminent professional society in tropical medicine, and the annual meeting of the society is an ideal place to share scientific advances in response to EVD, an interchange that benefits both the United States and all countries facing the current epidemic. Prospective conference attendees who are actively engaged in the EVD response were prepared to share their experiences in scientific sessions, but some could not attend. Numerous attendees from west Africa, including countries not directly affected by EVD, may have been afraid to attend because of not knowing whether they would be turned away on arrival. Moreover, the DOHH reiterated their travel ban for attendees of the annual conference of the American Public Health Association held November 15–19 in New Orleans.Ebola virus causes a deadly disease, and it typically occurs in places that have underresourced and overwhelmed health systems; whereas prior outbreaks have been small and contained, the current outbreak in west Africa is of unprecedented scale.² In September of 2014, the World Health Organization declared the current Ebola virus disease (EVD) outbreak a major threat to global health and security and requested that all global health organizations and supporting countries maximize their efforts to combat the disease at its source.³ Sporadic cases in high-income countries have occurred connected to this outbreak. Because the virus is known to be transmitted by physical contact, the risk of an EVD epidemic in countries with well-equipped public health and medical systems is small. In the past, limited quarantine procedures and travel bans have been enacted for highly contagious diseases, such as Severe Acute Respiratory Syndrome (SARS). However, considering limited transmission of Ebola virus to casual contacts, there is no evidence to suggest that these strategies are needed to control EVD. On the contrary, there are detrimental consequences of inappropriately combating the outbreak in this manner. For one, health professionals who are desperately needed to combat the disease at its source are disincentivized to risk their own health.⁴ Current fear-fueled policies issued by several states in the United States are causing significant stigma toward health workers, their families, and the organizations that respond to EVD epidemics; they also marginalize people of west African descent who live in the United States and have not had any exposure to EVD.⁵ This would not be the first time that irrational reactions hampered scientific advancement and harmed patients—during the early Acquired Immune Deficiency Syndrome (AIDS) epidemic, at-risk populations were similarly marginalized.Unfounded policies, such as the Louisiana DOHH response, also have the potential to encourage potentially exposed individuals to travel outside of monitored routes, deny their exposure, and avoid diagnosis and isolation when symptomatic. Instead, the DOHH should adopt policies based on evidence, such as the established protocols of Médecins Sans Frontières and the CDC,⁶ which advise monitoring returned asymptomatic health workers. These are effective and should continue to be the basis for a response to EVD in the United States.In the case of the current EVD epidemic and other public health crises, there is a need for greater advocacy on the part of health professionals and academic and professional institutions. Beyond the responsibility of providers to care for individual patients, health professionals should raise awareness about the public health implications of inappropriate responses and policies to public health crises. The medical community should unite and attack inappropriate policies to better protect our patients and their communities. Broader advocacy at the national level and within professional societies is needed to eschew fear-induced and political decisions and maintain evidence-based, neutral, and destigmatizing responses. Such actions would serve to refocus discussion on the evidence and show solidarity on the part of health professionals with the affected population as well as the heroic providers who have chosen to combat Ebola at its source.     

A novel approach to improve undergraduate surgical teaching

Background:

Undergraduate surgery is at an important crossroads. Many departments report significant difficulties delivering effective teaching. Our student feedback indicated a dated surgical curriculum lacking structure, quality and uniformity. We report on a new ”blended” approach employing a combination of professional DVDs, case based discussions, online material and traditional bedside teaching designed to provide structure, standardization, and equality of learning .

Methods:

Year 4 students who had undertaken the new course and year 5 students who had participated in the traditional teaching programme were compared. Students completed a 20 item questionnaire about their experiences of the surgical teaching programme.

Results:

One hundred and seventy-one year 4 (70%) and148 year 5 students (66%) responded. Domains relating to “Overall Satisfaction with the course”, “Approval of innovative teaching methods and interactivity” and “Satisfaction with the clarity of course information” showed improvements when comparing the new and old programmes. However bedside teaching was not rated as highly in the new programme (p<0.05).

Conclusion:

This blended approach has resulted in improved student understanding and engagement. The apparent compromise of bedside teaching may be a reflection of higher expectations. We believe that a similar blended approach has the potential to re-invigorate surgical teaching elsewhere.     

Expression of phosphatase of regenerating liver-3 (PRL-3) in endometrioid cancer and lymph nodes metastases

PurposeWe identify the expression of PRL-3 in primary endometrioid endometrial cancer and metastases in relation to the clinicopathological characteristics.Material/MethodsThe study involved 30 patients with type I endometrial cancer. Twelve of them were diagnosed with metastases in various localization of abdomen. The PRL-3 expression was evaluated on the basis of immunohistochemistry results by the use of monoclonal antibody anti-PRL3 clone 3B6.ResultsThe intensity of PRL-3 expression in correlation with tumor stage was statistically significant (p = 0.024). The strongest reaction was noted in cases classified as a 1a and 1b stage defined by FIGO. The strength of PRL-3 expression is significantly associated with the degree of histological tumor grade (p = 0.035).ConclusionsThe strong expression of PRL-3 in the primary tumor that was significantly correlated with the grade and clinical stage suggest that PTP4A3 participates in the process of endometrial carcinogenesis.