Early Alzheimer's disease pathology in human cortex involves transient cell states

Cellular perturbations underlying Alzheimer's disease (AD) are primarily studied in human postmortem samples and model organisms. Here, we generated a single-nucleus atlas from a rare cohort of cortical biopsies from living individuals with varying degrees of AD pathology. We next performed a systematic cross-disease and cross-species integrative analysis to identify a set of cell states that are specific to early AD pathology. These changes-which we refer to as the early cortical amyloid response-were prominent in neurons, wherein we identified a transitional hyperactive state preceding the loss of excitatory neurons, which we confirmed by acute slice physiology on independent biopsy specimens. Microglia overexpressing neuroinflammatory-related processes also expanded as AD pathology increased. Finally, both oligodendrocytes and pyramidal neurons upregulated genes associated with β-amyloid production and processing during this early hyperactive phase. Our integrative analysis provides an organizing framework for targeting circuit dysfunction, neuroinflammation, and amyloid production early in AD pathogenesis.

Early Alzheimer's disease pathology in human cortex is associated with a transient phase of distinct cell states

Cellular perturbations underlying Alzheimer's disease are primarily studied in human postmortem samples and model organisms. Here we generated a single-nucleus atlas from a rare cohort of cortical biopsies from living individuals with varying degrees of Alzheimer's disease pathology. We next performed a systematic cross-disease and cross-species integrative analysis to identify a set of cell states that are specific to early AD pathology. These changes-which we refer to as the Early Cortical Amyloid Response-were prominent in neurons, wherein we identified a transient state of hyperactivity preceding loss of excitatory neurons, which correlated with the selective loss of layer 1 inhibitory neurons. Microglia overexpressing neuroinflammatory-related processes also expanded as AD pathological burden increased. Lastly, both oligodendrocytes and pyramidal neurons upregulated genes associated with amyloid beta production and processing during this early hyperactive phase. Our integrative analysis provides an organizing framework for targeting circuit dysfunction, neuroinflammation, and amyloid production early in AD pathogenesis.

Single-cell genomic profiling of human dopamine neurons identifies a population that selectively degenerates in Parkinson's disease

The loss of dopamine (DA) neurons within the substantia nigra pars compacta (SNpc) is a defining pathological hallmark of Parkinson's disease (PD). Nevertheless, the molecular features associated with DA neuron vulnerability have not yet been fully identified. Here, we developed a protocol to enrich and transcriptionally profile DA neurons from patients with PD and matched controls, sampling a total of 387,483 nuclei, including 22,048 DA neuron profiles. We identified ten populations and spatially localized each within the SNpc using Slide-seq. A single subtype, marked by the expression of the gene AGTR1 and spatially confined to the ventral tier of SNpc, was highly susceptible to loss in PD and showed the strongest upregulation of targets of TP53 and NR2F2, nominating molecular processes associated with degeneration. This same vulnerable population was specifically enriched for the heritable risk associated with PD, highlighting the importance of cell-intrinsic processes in determining the differential vulnerability of DA neurons to PD-associated degeneration.

Early evidence of the impact of legal responses to COVID-19

This short presentation will consider how rights and equity challenges may be addressed in responding to epidemic diseases.

Syringe prescription to prevent HIV infection in Rhode Island: a case study

Injection drug users (IDUs) are a population at high risk for many diseases, including AIDS, and are clearly in need of medical and substance abuse treatment. Access to sterile syringes is critical for lowering the risk of transmission of HIV and other blood-borne pathogens among IDUs. Previously tried strategies include needle exchange programs and changing laws to allow the legal purchase and possession of syringes. An alternative strategy is to have physicians prescribe syringes to IDUs. To the best of our knowledge, this has previously been tried by only a few physicians in rare situations and never on a programmatic basis. This report describes the genesis of physician's syringe prescription in Rhode Island and some of the lessons learned to date. Because of the illicit nature of drug use, a tremendous amount of mistrust and fear on the part of IDUs often leads to poor interaction with the medical establishment. Prescription of syringes by a physician can serve as a tool for reaching out to a high-risk and often out-of-treatment population of drug users. It is a way for the health care community to tap into drug-using networks and bring those populations into a medical care system.

The EEOC charge priority policy and claimants with psychiatric disabilities

OBJECTIVE

In June 1995 the U.S. Equal Employment Opportunity Commission (EEOC) instituted a new charge priority policy. Under the new policy, charges are classified as one of three priority levels during or immediately after intake. Only charges assigned a high priority receive a full investigation. This paper examines the effect of the charge priority policy on individuals with psychiatric disabilities who filed Americans With Disabilities Act (ADA) charges with the EEOC.

METHODS

Using data extracted from the EEOC's charge data system, the authors analyzed all 66,298 ADA claims prioritized and closed between June 1995 and March 1998. The z test for difference in proportions and the generalized estimating equations procedure were used. The primary outcome measure was the priority assignment received by ADA claimants.

RESULTS

Charges that received a high priority assignment were more likely to result in benefits for claimants. Charges filed by claimants with psychiatric disabilities were significantly less likely to be assigned a high priority than charges filed by other claimants. Claimants with psychiatric disabilities were also significantly less likely to benefit from their claims.

CONCLUSIONS

The strong relationship between being assigned high priority and receiving benefits as a result of filing a charge demonstrates the importance of accurate priority categorization. The finding that people with psychiatric disabilities are less likely than others to benefit from their claims is cause for concern, particularly given the fact that the accuracy of the charge prioritization system has not been validated.

Differential response of human and bovine platelets to bovine von Willebrand factor and vascular subendothelium

Human platelets undergo agglutination when stirred with bovine plasma (BP), but bovine platelets do not. The present study has shown that exposure of washed bovine platelets to subthreshold concentrations of adenosine diphosphate or thrombin before stirring restores their sensitivity to BP, and the cells undergo rapid agglutination. This agglutination was prevented by a monoclonal antibody, to glycoprotein GPIb. Flow cytometry studies revealed that exposure of bovine platelets to thrombin caused an increase in their ability to bind antibodies known to react with human GPIb or GPIIb-IIIa receptors. Interaction of bovine and human platelets with vascular subendothelium revealed additional differences in reactivity. Bovine platelets in citrate anticoagulant reacted poorly with subendothelium under flow conditions compared with human platelets. In contrast, bovine platelets in blood with low molecular weight heparin as anticoagulant adhered more readily than human cells. These findings suggest that different mechanisms are involved in hemostasis in human and bovine species.

Prescribing syringes to prevent HIV: a survey of infectious disease and addiction medicine physicians in Rhode Island

This article describes the assessment of physicians' attitudes and practices regarding prescribing syringes to injection drug users (IDUs). A brief, anonymous, self-administered questionnaire was sent to all Infectious Disease and Addiction Medicine specialists in Rhode Island. Of 49 eligible physicians, 39 responded (response rate 80%). Most (95%) indicated that there is a legitimate medical reason for IDUs to obtain sterile syringes. Many (71%) agreed that they would prescribe syringes to prevent disease in IDUs if it were clearly legal to do so. We can conclude that physician syringe prescription to IDUs may be an acceptable supplement to existing HIV prevention strategies.

Surveillance, social risk, and symbolism: framing the analysis for research and policy

Name-based surveillance for HIV, considered alone, is a useful public health measure; its benefits outweigh its direct costs. There is little evidence that name-based surveillance directly deters individuals at risk of HIV from being tested, or exposes them to significant social risks. Yet such surveillance is chronically controversial. Understood in a broader context of the social risks and symbolic politics of HIV, as subjectively experienced by people at risk, this opposition is both rational and instructive. Although often discussed, the social risks of HIV infection are poorly understood. To the extent these risks have been addressed by privacy and antidiscrimination laws, the solution has been less complete than many public health professionals appear to believe: developments in law and policy, including the increasing prevalence of criminal HIV transmission laws and proposed changes in HIV testing and counseling standards, are contextual factors that help explain the opposition to name-based surveillance. Rather than focusing piecemeal on specific "barriers" to testing and care, an appreciation of the surveillance debate in context suggests a positive undertaking in public health policy to provide the conditions of opportunity, information, motivation and confidence that people with HIV need to accept an effective program of early intervention.

Physician prescribing of sterile injection equipment to prevent HIV infection: time for action

Injection drug users, their sex partners, and their children are at high risk for acquiring HIV infection and other bloodborne diseases. The risk for disease transmission in the United States is partly the result of restricted access to sterile injection equipment. Physicians and pharmacists can play an important role in providing syringe access by prescribing and dispensing syringes to patients who use injection drugs and cannot or will not enter drug treatment Prescribing and dispensing injection equipment are ethical, clinically appropriate, and fully consistent with current public health guidelines on disease prevention. An analysis of the laws of the 50 U.S. states, the District of Columbia, and Puerto Rico finds that physicians in nearly all these jurisdictions may legally prescribe sterile injection equipment to prevent disease transmission among drug-using patients and that pharmacists in most states have a clear or reasonable legal basis for filling the prescriptions. Given these medical and legal findings, physicians may wish to take a larger role in improving access to sterile injection equipment by prescribing this equipment for their patients where this practice is legal, and by joining efforts to change the law where it poses a barrier.

Syringe laws and pharmacy regulations are structural constraints on HIV prevention in the US

OBJECTIVE

To review the legal and regulatory barriers that restrict pharmacy sales of syringes to injection drug users (IDUs) and to discuss how reducing these barriers can facilitate access to sterile syringes for IDUs and improve HIV prevention.

BACKGROUND

IDUs' access to sterile syringes from community pharmacies in the United States is limited by state laws and regulations governing syringe sales. Restricted availability of sterile syringes from pharmacies is a structural barrier that greatly impedes HIV prevention for IDUs, who often share and reuse syringes because they cannot obtain and possess sterile syringes. These high-risk behaviors contribute to the transmission of HIV and other blood-borne pathogens among IDUs, their sexual partners, and their children. STATE EXPERIENCES: In Connecticut, because of high HIV prevalence among IDUs, restrictive syringe laws were changed. After the legal changes in Connecticut, both pharmacy sales of syringes in areas of high drug use and purchases of syringes in pharmacies (reported by IDUs) increased, while syringe sharing (reported by IDUs) decreased. Maine and Minnesota have made similar changes in laws.

CONCLUSIONS

Increasing access to sterile syringes through pharmacies requires the repeal or modification of legal barriers. Pharmacy sale of syringes to IDUs is an inexpensive HIV prevention intervention with the potential to substantially reduce HIV transmission. Further studies are needed to document how changes to legal barriers can influence HIV prevention for IDUs.

Outcomes of employment discrimination charges filed under the Americans With Disabilities Act

OBJECTIVE

The outcomes of employment discrimination charges filed under the Americans With Disabilities Act (ADA) by individuals with psychiatric disabilities and those with other disabilities were compared.

METHODS

Data obtained from the Equal Employment Opportunity Commission (EEOC) consisted of all ADA employment claims closed as of March 31, 1998. Charges were categorized by whether they were investigated by the EEOC or by a Fair Employment Practice Agency (FEPA).

RESULTS

Of the 175,226 charges filed, 83.2 percent were closed by March 31, 1998. Of these, 15.7 percent brought some kind of benefit to charging parties, although only 1.7 percent resulted in new hires or reinstatements. Of charges investigated by FEPAs, 23.3 percent led to some benefit, compared with 11.5 percent of charges investigated by the EEOC. Of charges investigated by the EEOC, the median actual monetary benefit was $5,646, compared with $2,400 for charges investigated by FEPAs. A total of 13.6 percent of charges filed by individuals with psychiatric disabilities resulted in benefits, compared with a benefit rate of 16 percent for persons with other disabilities. The median actual monetary benefit received by persons with psychiatric disabilities was $5,000, compared with $3,500 for those with nonpsychiatric disabilities. Individuals whose charges were investigated in the first three years of ADA implementation were more likely to receive benefits than individuals whose charges were investigated more recently.

CONCLUSIONS

Most employment discrimination charges filed under the ADA do not result in benefits or a finding of reasonable cause. Outcomes for people with psychiatric disabilities do not differ substantially from those for people with other disabilities.

Influence of thrombin in suspension, surface activation, and high shear on platelet surface GPIb/IX distribution

Studies in our laboratory have shown that glycoprotein Ib/IX (GPIb/IX), the receptor for von Willebrand factor (vWf), is not decreased in number or cleared from exposed surfaces to the internal membranes of platelets activated in suspension by thrombin alone, by interaction with formvar surfaces alone, or by a combination of the two modes of stimulation. The present study has examined the influence of three different types of stimulation including activation by thrombin in suspension followed by surface activation on formvar, then exposure to high shear stress in a flat chamber. Samples were fixed for study in the electron microscope after each single stimulus, after the combination of two modes of activation, and after the combination of suspension, surface, and shear activation and were stained by an immunogold procedure using monoclonal antibodies to localize GPIb/IX on singly, doubly, or multiply activated cells. The results demonstrate that GPIb/IX receptors remain on activated platelets from edge to edge and that there is no difference in the number or distribution of receptor complexes on thrombin-activated platelets, surface-activated cells, or platelets exposed to the combination of suspension, surface, and shear activation. The findings add additional support to the concept that GPIb/IX is not a mobile receptor and is not cleared from exposed surfaces to internal membranes under physiologic conditions.

Different paths to justice: the ADA, employment, and administrative enforcement by the EEOC and FEPAs

Under Title I of the ADA, individuals who believe they have been subjected to disability-based employment discrimination may file an administrative charge. This article looks at who files charges; over what issues, and with what outcomes in both Equal Employment Opportunity Commission (EEOC) field offices, and state and local fair employment practice agencies (FEPAs). The data for the article are computerized records of all ADA charges filed through March 31, 1998. The data indicate that individuals who rely on a FEPA to investigate their charge have a greater likelihood of obtaining a beneficial outcome than individuals who rely on the EEOC, but proportionately more individuals receiving a beneficial outcome are likely to receive monetary benefits from the EEOC than from a FEPA. Further, those who receive beneficial outcomes will probably receive greater monetary benefits from charges investigated by the EEOC than from those investigated by a FEPA.

The law and the public's health: a study of infectious disease law in the United States

Law plays crucial roles in the field of public health, from defining the power and jurisdiction of health agencies, to influencing the social norms that shape individual behavior. Despite its importance, public health law has been neglected. Over a decade ago, the Institute of Medicine issued a report lamenting the state of public health administration, generally, and calling, in particular, for a revision of public health statutes. The Article examines the current state of public health law. To help create the conditions in which people can be healthy, public health law must reflect an understanding of how public health agencies work to promote health, as well as the political and social contexts in which these agencies operate. The authors first discuss three prevailing ways in which the determinants of health are conceptualized, and the political and social problems each model tends to create for public health efforts. The analysis then turns to the core functions of public health, emphasizing how law furthers public health work. The Article reports the results of a fifty-state survey of communicable disease control law, revealing that few states have systematically reformed their laws to reflect contemporary medical and legal developments. The Article concludes with specific guidelines for law reform.

The invisibility of public health: population-level measures in a politics of market individualism

This paper models the prevailing political attack on government as a heuristic, a judgmental strategy that simplifies complex phenomena by applying simple tests to a limited set of relevant data. The heuristic of market individualism offers three tools for analyzing the problems of governing: the supremacy of the free market as a regulatory device, a belief in individual freedom of choice and personal responsibility, and the elevation of individual satisfaction as the chief goal of society. Because public health is inherently concerned with the health of the population rather than individual health, because the market itself is a major source of ill health, and because individual choice is socially mediated, use of the heuristic precludes the recognition of the value of public health work. Although some degree of accommodation to current political realities is a practical necessity, public health advocates must not neglect the task of fashioning radically different alternative visions over the long term.

The professional responsibility for care

Access to dental care is an essential need for all patients, particularly for individuals with complex medical conditions. Consequently, dentists have a moral and professional obligation to provide care for all individuals within the dentist's realm of expertise. However, throughout the HIV epidemic dental professionals have demonstrated an unwillingness to treat infected patients. This article addresses common objections raised by dentists unwilling to provide care, and discusses the professional obligation to treat and the importance of professionalism in reducing discrimination.

Influence of cytochalasin B (CB) on GP Ib distribution after thrombin or TRAP and before surface activation

The receptor for von Willebrand factor (vWF) on human platelets, glycoprotein (GP) Ib/IX, has been shown in our studies to be an immobile complex when stimulated in suspension or on surfaces. Recent investigations have revealed that GP Ib/IX remains immobile on platelets activated in suspension followed by exposure to formvar surfaces that cause the cells to spread. However, since channels of the open canalicular system (OCS) are evaginated back on to the exposed surface during spreading, it was suggested that our study missed the clearance of GP Ib/IX from the exposed surface to internal membranes. The present study has added cytochalasin B after exposure of platelets to thrombin or TRAP in suspension in order to prevent spreading and movement of GP Ib/IX during subsequent exposure to surface activation on formvar grids. Results indicate that GP Ib/IX receptors remain randomly dispersed from edge to edge on platelets activated by thrombin or TRAP in suspension 10 minutes before treatment with CB followed by surface activation. Statistical analysis of the frequency of immunogold particles binding to monoclonal antibodies attached to GP Ib/IX revealed no significant reduction in frequency, translocation from cell edges or concentration of GP Ib/IX receptors in or around channels of the OCS. Results support the concept that GP Ib/IX is not cleared from exposed surfaces to the OCS of platelets activated by thrombin or TRAP and surface activation.

The legal strategies used in operating syringe exchange programs in the United States

OBJECTIVES

This study sought to identify the strategies used by syringe exchange programs to establish their legality.

METHODS

Statutes, court decisions, published studies of exchange programs, and news stories were reviewed, and telephone interviews were conducted with syringe exchange personnel.

RESULTS

Twenty-seven exchanges have been authorized by amendments to or judicial interpretations of state drug laws or by administrative action under such laws, or operate in a state that has no laws regulating needles. At least 13 programs operate under claims of legality based on local interpretations of state law, principally public health law. The remaining syringe exchanges operate without a claim of legality.

CONCLUSIONS

The deployment of syringe exchanges has been hindered by concerns about their legal status. This study shows that the applicability of drug laws to syringe exchange is open to dispute, and that local public health authorities may under some circumstances rely on their own legal authority to fund or operate syringe exchange programs.

Legal considerations in infectious diseases and dentistry

Dentists, similar to other professionals subject to legal regulation, often have an overly simple view of the legal system. Communicable diseases present questions on the cutting edge of the law, and, as the previous discussion makes perhaps painfully clear, there is considerable uncertainty on many important legal points. Legal uncertainty is often a reflection of social or scientific uncertainty. Clear answers emerge less from the words of lawyers and judges than from the actions of professionals themselves, who ultimately set the standard of care. In any area of legal uncertainty, the dentist is best advised to adhere to the best scientific information available and to meet the ethical standards of the profession.

Human immunodeficiency virus-infected health care workers: the restoration of professional authority

During the first years of the human immunodeficiency virus (HIV) epidemic, the professional limitation on HIV-infected physicians and other health care workers were left to the discretion of the infected workers themselves and the medical institutions in which they worked. In the crisis occasioned by the report of iatrogenic infection in a Florida dental practice, the legal system was expected to develop mandatory standards for the management of an estimated 50 000 American health care workers with HIV. Evaluation of the legal developments of the past 3 years, including state practice guidelines, tort law, and disability discrimination law, suggests that judges and regulators have been unwilling or unable to set a binding standard. This offers the medical profession a second chance to formulate and educate the public about a socially responsible, nonrestrictive policy.

Relationship of actin filament assembly to clearance of fibrinogen gold, GPIIb-IIIa complexes on spread platelets

The present study has evaluated the influence of high concentrations of cytochalasins B and E on the detergent-resistant actin levels in fully spread platelets by PAGE gel electrophoresis, and the effects of the two inhibitors of new actin filament assembly on translocation of fibrinogen gold (Fgn/Au) labelled GPIIb-IIIa receptors on the surface-activated cells. Concentrations of 10(-4) M and 10(-5) M cytochalasin B and E reduced detergent-resistant actin in fully spread platelets to levels present in resting discoid platelets in suspension. Despite reduction of actin filaments to levels in resting cells, cytochalasin B did not prevent translocation of Fgn/Au from platelet margins into channels of the open canalicular system (OCS). Similar concentrations of cytochalasin E completely blocked translocation of receptor-ligand complexes and produced a patching phenomenon not observed in previous studies. Rinsing of the spread cells to remove cytochalasin, followed by incubation of the treated platelets in Hank's buffered salt solution (HBSS) restored levels of detergent-resistant actin to those found in untreated, spread platelets. Resting grids of 10(-5) M cytochalasin E-treated platelets on drops of HBSS for 15 min restored their ability to clear FGN/Au linked to GPIIb-IIIa from exposed surfaces to the OCS, but 10(-4) M cytochalasin E-treated cells remained anergic after incubation on drops of HBSS. Thus a fully assembled cytoplasmic actin filament cytoskeleton does not appear to be essential for translocating receptor-ligand complexes on the platelet surface to the OCS, nor does its presence guarantee that the ability to clear GPIIb-IIIa receptors will be restored.

Thoughts on the law and the public's health

One understanding of health conceives of it as a state of freedom from pathology, achieved by an individual, through the mediation of a doctor. On this view, improvements in health flow from the application of science to specific ills of the body, and access to medical care is the chief determinant of health. This “medicalized” view of health underlies the current debate over medical care payment reform. This is the dominant way of talking about health.

An alternative is the view of health commonly associated with the practice of public health. On this view, health is an attribute of communities in social and physical environments. Health takes its shape in large numbers—in morbidity and mortality statistics—and, ideally, includes not just a high level of well-being for some, but also its even distribution throughout a society. Improvements in health are seen to arise from healthful changes in the environment.

Four fluorescence polarization immunoassays for therapeutic drug monitoring evaluated

We evaluated four fluorescence polarization immunoassays--those for phenytoin, procainamide, N-acetylprocainamide (NAPA), and quinidine--from Roche Diagnostic Systems, done in the Cobas Bio FP centrifugal analyzer. The assays for phenytoin, NAPA, and quinidine demonstrated a linear response over the expected ranges of concentrations, and analytical recovery of test drug added to drug-free sera was greater than 90%. However, recovery in the procainamide assay was poor (69-82%) for samples containing greater than 8 mg/L, owing to nonlinearity. Results of method-comparison studies of the four assays paralleled the recovery studies, although the quinidine assay demonstrated a bias (1.0 mg/L higher) when compared with EMIT (Syva). The precision of the phenytoin assay was acceptable at all concentrations tested (total CV less than 7.0%). Imprecision of the other assays was significant at certain concentrations: total CV greater than 10.0% at subtherapeutic values for NAPA and quinidine, and greater than 9.0% for low (2.4 mg/L) and moderate concentrations (9.6 mg/L) of procainamide. Interferences were not significant for hemolyzed, icteric, or lipemic specimens or for specimens with added drug metabolites. The calibration curves for all four assays had good stability (greater than 60 days).

Four fluorescence polarization immunoassays for therapeutic drug monitoring evaluated

We evaluated four fluorescence polarization immunoassays--those for phenytoin, procainamide, N-acetylprocainamide (NAPA), and quinidine--from Roche Diagnostic Systems, done in the Cobas Bio FP centrifugal analyzer. The assays for phenytoin, NAPA, and quinidine demonstrated a linear response over the expected ranges of concentrations, and analytical recovery of test drug added to drug-free sera was greater than 90%. However, recovery in the procainamide assay was poor (69-82%) for samples containing greater than 8 mg/L, owing to nonlinearity. Results of method-comparison studies of the four assays paralleled the recovery studies, although the quinidine assay demonstrated a bias (1.0 mg/L higher) when compared with EMIT (Syva). The precision of the phenytoin assay was acceptable at all concentrations tested (total CV less than 7.0%). Imprecision of the other assays was significant at certain concentrations: total CV greater than 10.0% at subtherapeutic values for NAPA and quinidine, and greater than 9.0% for low (2.4 mg/L) and moderate concentrations (9.6 mg/L) of procainamide. Interferences were not significant for hemolyzed, icteric, or lipemic specimens or for specimens with added drug metabolites. The calibration curves for all four assays had good stability (greater than 60 days).