Genetic determinants of sex in placental mammals developed by the evolution of primordial autosomes into the male and female sex chromosomes. The Y chromosome determines maleness by the action of the gene SRY, which encodes a protein that initiates a sequence of events prompting the embryonic gonads to develop into testes. The X chromosome in the absence of a Y chromosome results in a female by permitting the conversion of the embryonic gonads into ovaries. We trace the historical progress that resulted in the discovery that one X chromosome in the female is randomly inactivated in early embryogenesis, accomplishing approximate equivalency of X chromosome gene dosage in both sexes. This event results in half of the somatic cells in a tissue containing proteins encoded by the genes of the maternal X chromosome and half having proteins encoded by the genes of the paternal X chromosome, on average, accounting for the phenotype of a female heterozygote with an X chromosome mutation. The hypothesis of X chromosome inactivation as a random event early in embryogenesis was first described as a result of studies of variegated coat color in female mice. Similar results were found in women using the X chromosome-linked gene, glucose-6-phosphate dehydrogenase, studied in red cells. The random inactivation of the X chromosome-bearing genes for isoenzyme types A and B of glucose-6-phosphate dehydrogenase was used to establish the clonal origin of neoplasms in informative women with leiomyomas. Behind these discoveries are the stories of the men and women scientists whose research enlightened these aspects of X chromosome function and their implication for medicine.
Robotic cardiac operations evolved from minimally invasive operations and offer similar theoretical benefits, including less pain, shorter length of stay, improved cosmesis, and quicker return to preoperative level of functional activity. The additional benefits offered by robotic surgical systems include improved dexterity and degrees of freedom, tremor-free movements, ambidexterity, and the avoidance of the fulcrum effect that is intrinsic when using long-shaft endoscopic instruments. Also, optics and operative visualization are vastly improved compared with direct vision and traditional videoscopes. Robotic systems have been utilized successfully to perform complex mitral valve repairs, coronary revascularization, atrial fibrillation ablation, intracardiac tumor resections, atrial septal defect closures, and left ventricular lead implantation. The history and evolution of these procedures, as well as the present status and future directions of robotic cardiac surgery, are presented in this review.
Hematopoietic stem cell transplantation is a highly specialized and unique medical procedure. Autologous transplantation allows the administration of high-dose chemotherapy without prolonged bone marrow aplasia. In allogeneic transplantation, donor-derived stem cells provide alloimmunity that enables a graft-versus-tumor effect to eradicate residual disease and prevent relapse. The first allogeneic transplantation was performed by E. Donnall Thomas in 1957. Since then the field has evolved and expanded worldwide. New indications beside acute leukemia and aplastic anemia have been constantly explored and now include congenital disorders of the hematopoietic system, metabolic disorders, and autoimmune disease. The use of matched unrelated donors, umbilical cord blood units, and partially matched related donors has dramatically extended the availability of allogeneic transplantation. Transplant-related mortality has decreased due to improved supportive care, including better strategies to prevent severe infections and with the incorporation of reduced-intensity conditioning protocols that lowered the toxicity and allowed for transplantation in older patients. However, disease relapse and graft-versus-host disease remain the two major causes of mortality with unsatisfactory progress. Intense research aiming to improve adoptive immunotherapy and increase graft-versus-leukemia response while decreasing graft-versus-host response might bring the next breakthrough in allogeneic transplantation. Strategies of graft manipulation, tumor-associated antigen vaccinations, monoclonal antibodies, and adoptive cellular immunotherapy have already proved clinically efficient. In the following years, allogeneic transplantation is likely to become more complex, more individualized, and more efficient.
The “curative potential” in almost any clinical setting depends on a caregiver establishing and maintaining an empathic connection with patients so as to achieve “narrative competence” in discerning and acting in accord with their preferences and best interests. The “narrative medicine” model of shared “close reading of literature and reflective writing” among clinicians as a means of fostering a capacity for clinical empathy has gained validation with recent empirical studies demonstrating the enhancement of theory of mind (ToM), broadly conceived as empathy, in readers of literary fiction. Talmudic legends, like that of Rabbi Judah’s death, are under-appreciated, relevant sources of literary fiction for these efforts. The limitations of narrative medicine are readily counterbalanced by simultaneously practiced attention to traditional bioethical principles, including—especially—beneficence, non-maleficence, and autonomy.
Suicidal phenomena in the general hospital can take a variety of forms that can be parsed by taking into account whether or not the patient 1) intended to hasten death, and 2) included collaborators, including family and health care providers, in the decision to act. These two criteria can be used to distinguish entities as diverse as true suicide, non-compliance, euthanasia/physician-assisted suicide, and hospice/palliative care. Characterizing the nature of “suicide” events facilitates appropriate decision-making around management and disposition.
In rare cases, the monoclonal immunoglobulin that characterizes essential monoclonal gammopathy interacts with a self-antigen with functional consequences and a resulting clinical syndrome. This event is presumably random and results from the clone of B lymphocytes making a monoclonal immunoglobulin that simulates an autoimmune antibody. Thus, by chance, the monoclonal immunoglobulin has sufficient affinity for an epitope on a normal protein that functional consequences ensue. One such rare event is the synthesis and secretion of a monoclonal immunoglobulin that binds to human insulin. Inactivation of insulin by antibody results in (1) an early postprandial hyperglycemia, (2) followed by either or both (i) a reactive overshot in insulin secretion, as a result of hypertrophied or hyperplastic islet beta cells, later falling glucose levels, and (ii) an unpredictable dissociation of insulin from the complex, and, several hours later, (3) a resultant increase in free insulin levels and severe hypoglycemia with clinical consequences, ranging from sweating, dizziness, headache, and tremors to confusion, seizures, and unconsciousness. These attacks are invariably responsive to glucose administration. This very uncommon manifestation of a monoclonal gammopathy can occur in patients with essential monoclonal gammopathy or myeloma. The monoclonal anti-insulin immunoglobulin in monoclonal gammopathy has a low affinity for insulin, but has a high capacity for insulin-binding, resulting in the syndrome of episodic hypoglycemic attacks. This phenomenon of an insulin-binding monoclonal immunoglobulin simulates the acquired insulin autoimmune syndrome, although the latter is mediated by a polyclonal antibody response in the majority of cases studied, and has linkage to HLA class II alleles.
CD4+CD25+Foxp3+ regulatory T cells (Treg) are critical to the maintenance of immune tolerance. Treg are known to utilize a number of molecular pathways to control immune responses and maintain immune homeostasis. Fibrinogen-like protein 2 (FGL2) has been identified by a number of investigators as an important immunosuppressive effector of Treg, which exerts its immunoregulatory activity by binding to inhibitory FcγRIIB receptors expressed on antigen-presenting cells including dendritic cells, endothelial cells, and B cells. More recently, it has been suggested that FGL2 accounts for the immunosuppressive activity of a highly suppressive subset of Treg that express T cell immunoreceptor with Ig and ITIM domains (TIGIT). Here we discuss the important role of Treg and FGL2 in preventing alloimmune and autoimmune disease. The FGL2–FcγRIIB pathway is also known to be utilized by viruses and tumor cells to evade immune surveillance. Moving forward, therapies based on modulation of the FGL2–FcγRIIB pathway hold promise for the treatment of a wide variety of conditions ranging from autoimmunity to cancer.
The number needed to treat (NNT) is a simple measure of a treatment’s impact, increasingly reported in randomized trials and observational studies. It has been found to be incorrectly calculated in several studies involving varying follow-up times. We discuss the NNT in these contexts and illustrate the concept using several published studies. The computation of the NNT is founded on the cumulative incidence of the outcome. Instead, several published studies use simple proportions that do not account for varying follow-up times, or use incidence rates per person-time. We show how these approaches can lead to erroneous values of the NNT and misleading interpretations. For example, a trial of 3,845 very elderly hypertensives randomized to a diuretic or placebo reported a NNT of 94 treated for 2 years to prevent one stroke, though the correct approach results in a NNT of 63. We also note that meta-analyses involve trials of differing lengths, but often report a single NNT. For example a meta-analysis of 22 trials of the anticholinergic tiotropium in chronic obstructive pulmonary disease reported a NNT of 16 patients “over one year,” even if the trials varied in duration from 3 to 48 months, with the more specifically computed NNTs varying widely from 72, 15, and 250 for the 3-month, 12-month, and 48-month trials, respectively. Finally, we describe the value of the NNT in assessing benefit–risk, such as low-dose aspirin use in secondary prevention, where prevention of mortality was assessed against the risk of gastrointestinal bleeding. As the “number needed to treat” becomes increasingly used in the comparative effectiveness and safety of therapies, its accurate estimation and interpretation become crucial to avoid distorting clinical, economic, and public health decisions.
Feelings of guilt have tormented Holocaust survivors, ranging from immediately after the liberation to later in life, for shorter or longer periods, and persisting for some throughout their entire post-war lives. Descriptions of the guilt experienced by survivors of the Nazi camps occupy an impressive amount of literature: “Why me?” was the question, when a younger and more able family member perished; “Why me?” when more productive members of the community perished; “Why me?” when a million and a half children were deprived of their lives. Many found the answer by retelling their stories, witnesses of what happened. This type of guilt is much different from the recently described phenomenon of survivor syndrome, namely the secondary guilt felt by Nazi-persecuted Jewish writers. Despite successes in all aspects of their life, these writers developed a self-incriminating guilt due to their perceived inadequacy of communicating, particularly in light of the resurging anti-Semitism worldwide. This paper deals with the survival and suicides of Nazi-persecuted Jewish writers and offers a possible explanation for their late self-destructive acts.
