Racial/ethnic and income disparities in neighborhood-level broadband access in 905 US cities, 2017-2021.

OBJECTIVES: Broadband access is an essential social determinant of health, the importance of which was made apparent during the COVID-19 pandemic. We sought to understand disparities in broadband access within cities and identify potential solutions to increase urban access. STUDY DESIGN: This was a descriptive secondary analysis using multi-year cross-sectional survey data. METHODS: Data were obtained from the City Health Dashboard and American Community Survey. We studied broadband access in 905 large US cities, stratifying neighborhood broadband access by neighborhood median household income and racial/ethnic composition. RESULTS: In 2017, 30% of urban households across 905 large US cities did not have access to high-speed broadband internet. After controlling for median household income, broadband access in majority Black and Hispanic neighborhoods was 10-15% lower than in majority White or Asian neighborhoods. Over time, lack of broadband access in urban households decreased from 30% in 2017 to 24% in 2021, but racial and income disparities persisted. CONCLUSIONS: As an emerging social determinant, broadband access impacts health across the life course, affecting students' ability to learn and adults' ability to find and retain jobs. Resolving lack of broadband access remains an urban priority. City policymakers can harness recent infrastructure funding opportunities to reduce broadband access disparities.

Reproductive benefit of oxidative damage: an oxidative stress "malevolence"?

High levels of reactive oxygen species (ROS) compared to antioxidant defenses are considered to play a major role in diverse chronic age-related diseases and aging. Here we present an attempt to synthesize information about proximate oxidative processes in aging (relevant to free radical or oxidative damage hypotheses of aging) with an evolutionary scenario (credited here to Dawkins hypotheses) involving tradeoffs between the costs and benefits of oxidative stress to reproducing organisms. Oxidative stress may be considered a biological imperfection; therefore, the Dawkins' theory of imperfect adaptation of beings to environment was applied to the role of oxidative stress in processes like famine and infectious diseases and their consequences at the molecular level such as mutations and cell signaling. Arguments are presented that oxidative damage is not necessarily an evolutionary mistake but may be beneficial for reproduction; this may prevail over its harmfulness to health and longevity in evolution. Thus, Dawkins' principle of biological "malevolence" may be an additional biological paradigm for explaining the consequences of oxidative stress.

Novel bacterial acetyl coenzyme A carboxylase inhibitors with antibiotic efficacy in vivo.

The pseudopeptide pyrrolidinedione antibiotics, such as moiramide B, have recently been discovered to target the multisubunit acetyl coenzyme A (acetyl-CoA) carboxylases of bacteria. In this paper, we describe synthetic variations of each moiety of the modularly composed pyrrolidinediones, providing insight into structure-activity relationships of biochemical target activity, in vitro potency, and in vivo efficacy. The novel derivatives showed highly improved activities against gram-positive bacteria compared to those of previously reported variants. The compounds exhibited a MIC(90) value of 0.1 microg/ml against a broad spectrum of Staphylococcus aureus clinical isolates. No cross-resistance to antibiotics currently used in clinical practice was observed. Resistance mutations induced by pyrrolidinediones are exclusively located in the carboxyltransferase subunits of the bacterial acetyl-CoA carboxylase, indicating the identical mechanisms of action of all derivatives tested. Improvement of the physicochemical profile was achieved by salt formation, leading to aqueous solubilities of up to 5 g/liter. For the first time, the in vitro activity of this compound class was compared with its in vivo efficacy, demonstrating a path from compounds weakly active in vivo to agents with significant efficacy. In a murine model of S. aureus sepsis, the 100% effective dose of the best compound reported was 25 mg/kg of body weight, only fourfold higher than that of the comparator molecule linezolid. The obvious improvements achieved by chemical derivatization reflect the potential of this novel antibiotic compound class for future therapy.

Asymmetric synthesis of the northern half C1-C16 of the bryostatins.

Starting from 8-oxabicyclo[3.2.1]oct-6-en-3-one and racemic 2,2-dimethyl-8-oxabicyclo[3.2.1]oct-6-en-3-one, the C1-C16 segment of the bryostatins has been synthesized in 30 steps and 9% overall yield (17 steps longest linear sequence). Fragment coupling by dithiane strategy and protecting group manipulations provided an advanced chemodifferentiated northern half segment.

A clinical pathological comparison of three families with frontotemporal dementia and identical mutations in the tau gene (P301L)

We investigated three separate families (designated D, F and G) with frontotemporal dementia that have the same molecular mutation in exon 10 of the tau gene (P301L). The families share many clinical characteristics, including behavioural aberrations, defective executive functions, language deficits, relatively preserved constructional abilities and frontotemporal atrophy on imaging studies. However, Family D has an earlier mean age of onset and shorter duration of disease than Families F and G (49.0 and 5.1 years versus 61-64 and 7.3-8.0 years, respectively). Two members of Families D and F had neuropathological studies demonstrating lobar atrophy, but the brain from Family D had prominent and diffuse circular, intraneuronal, neurofibrillary tangles not seen in Family F. The brain from Family F had ballooned neurons typical of Pick's disease type B not found in Family D. A second autopsy from Family D showed neurofibrillary tangles in the brainstem with a distribution similar to that found in progressive supranuclear palsy. These three families demonstrate that a missense mutation in the exon 10 microtubule-binding domain of the tau protein gene can produce severe behavioural abnormalities with frontotemporal lobar atrophy and microscopic tau pathology. However, the findings in these families also emphasize that additional unidentified environmental and/or genetic factors must be producing important phenotypic variability on the background of an identical mutation. Apolipoprotein E genotype does not appear to be such a factor influencing age of onset in this disease.

Wide range in age of onset for chromosome 1--related familial Alzheimer's disease.

Mutations in three different genes on chromosomes 1, 14, and 21 cause autosomal dominant forms of familial Alzheimer's disease (FAD). Most result in an early-onset phenotype. However, several kindreds of Volga German ancestry have the same chromosome 1 gene mutation and demonstrate a relatively older mean age of onset and include individuals with late age of onset. In these families, the mean age of onset is 54.9 +/- 8.4 years (range, 40-75 years), mean age at death is 65.9 +/- 10.2 years (range, 43-88 years), and mean disease duration is 11.3 +/- 4.6 years (range, 5-23 years). This contrasts with a group of 7 families with chromosome 14 mutations in which the mean age of onset is 44.8 +/- 4.8 years (range, 30-55 years), mean age at death is 52.6 +/- 5.7 years (range, 39-65 years), and mean disease duration is 7.6 +/- 3.2 years (range, 2-17 years). (All means are significantly different in the 2 groups of families, p < 0.005.) In the chromosome 1 families, 7 persons (16%) had an age of onset at or older than 65 years and 22 (54%) survived to age 65 or older versus none in the chromosome 14 families. An example of probable nonpenetrance of disease at age 89 was also found in a chromosome 1 kindred. It is concluded that, unlike the chromosome 14 gene, mutations in the chromosome 1 FAD gene may result in individuals with a late age of onset overlapping with the more common sporadic form of the disease occurring in the general population. In light of the great variability in age of onset in persons with identical mutations, study of the genetic and environmental factors contributing to delayed onset of disease in chromosomal 1 FAD kindreds will be an important area for further investigation. Apolipoprotein E genotype may be one such factor that plays a partial role in this variability.

Phenotype of chromosome 14-linked familial Alzheimer's disease in a large kindred.

We report the clinical and neuropathological features of chromosome 14-linked familial Alzheimer's disease (14qFAD) in affected members of the L family. Some clinical information on all 16 known affected individuals and detailed neuropathological findings in 6 family members were available for review. Common features of the phenotype of 14qFAD in the L family included onset of dementia before the age of 50, early progressive aphasia, early-appearing myoclonus and generalized seizures, paratonia, cortical atrophy, numerous and extensive senile plaques and neurofibrillary tangles, and prominent amyloid angiopathy. Descriptions of phenotypic features were available for six additional recently defined 14q-linked FAD kindreds: the findings in four of them (FAD4, FAD2, A, B) indicated a relatively consistently shared 14qFAD phenotype, conforming closely with the specific clinical and neuropathological characteristics noted in the L family. Comparisons also suggested several ostensible phenotypic variants in 14qFAD: (1) In two 14q-linked kindreds (SNW/FAD3, FAD1), affected individuals in some instances were noted to survive to age 70 or beyond and the mean age at onset (> 49 years) in these two kindreds was somewhat higher than in their five 14qFAD counterparts (< 48 years in each); (2) in the SNW/FAD3 kindred, seizures and myoclonus were absent in all 10 subjects examined; and (3) cerebellar amyloid plaques were variably present within and among several 14qFAD kindreds. Comparisons with phenotypic features recently detailed in three kindreds (TOR3, F19, ROM) with codon 717 amyloid precursor protein gene mutations (i.e., APP717 FAD) suggested several distinctions: Prominent progressive aphasia, myoclonus, seizures, and paratonia were all apparently less prevalent in APP717 FAD, with language function predominantly spared over the initial disease course. The extent of homogeneity and heterogeneity in the clinical and neuropathological phenotype of 14q-linked FAD and its possible meaningful distinctions from the phenotypes of APP717 FAD await further determination.

Lack of detectable radiation hypersensitivity in lymphoblastoid cells from multiple pedigrees of familial Alzheimer disease.

Recent reports suggest that cultivated nonneuronal cells from individuals with Alzheimer disease (AD) and other specific hereditary neurodegenerative disorders show hypersensitivity to DNA-damaging agents such as x-rays and radiomimetic chemicals. The hypothesis proposed is that a number of chronic neurologic degenerations, including AD, may be the result of accumulation of damaged DNA, resulting from a defect in DNA repair. We investigated this hypothesis by evaluating cells from individuals from pedigrees of familial Alzheimer disease (FAD) for hypersensitivity to x-irradiation. Sensitivity was assayed by viability measured by trypan blue dye exclusion and micronucleus formation. We tested B-lymphoblastoid cell lines from nine patients and nine unaffected family members from pedigrees with FAD, three unrelated controls, three ataxia telangiectasia (AT) patients, and three Down syndrome individuals. The AT cell lines showed the expected reduced viability and increased micronucleus formation after x-ray treatment. The FAD and control lines showed marked heterogeneity with both assays. There was no significant differences between the FAD patients and controls. The wide variability in the response of cell lines from controls and patients indicates the need for more sensitive assays for detection of radiation sensitivity in cells from various neurologic disorders.

The validity of 3 clinical diagnostic criteria for Alzheimer's disease.

To examine the validity of criteria-based (clinical) diagnosis of Alzheimer's disease (AD), 4 physicians experienced in the evaluation of dementia patients applied 3 sets of diagnostic criteria to each of 62 patients based on standardized medical record information. Diagnostic outcome was validated by neuropathologic examination (completed previously) for all (43) demented patients and 4 nondemented patients and by follow-up in the remainder (15) with no dementia. Raters were blind to the composition of the study group as well as to the clinical and pathologic diagnoses. We evaluated 3 diagnostic criteria sets for AD: the American Psychiatric Association diagnostic criteria from the Diagnostic and Statistical Manual (DSM-III), the NINCDS-ADRDA Work Group criteria for the diagnosis of Alzheimer's disease (NINCDS), and the Eisdorfer and Cohen research diagnostic criteria for primary neuronal degeneration (ECRDC). ECRDC had the highest specificity (0.88) but also the greatest odds of false-negative diagnosis (LRneg = 0.61, sensitivity = 0.46). NINCDS had the best sensitivity (0.92, specificity = 0.65), and DSM-III showed intermediate values (sensitivity = 0.76, specificity = 0.80). We conclude that the investigator or clinician who wishes to ensure that patients classified as AD are more likely to be AD should choose DSM-III, whereas the investigator who wishes to include the greatest number of AD cases, seldom assigning a diagnosis of no AD to a true case, should choose NINCDS.

Interrater reliability of Alzheimer's disease diagnosis.

To determine interrater reliability of dementia diagnosis, 4 physicians experienced in the evaluation of dementia patients applied 3 sets of diagnostic criteria to each of 62 patients, based on a standardized set of medical record information. All patients had undergone similar examinations and follow-up to establish the initial clinical diagnosis (76% had autopsy). Raters were blind to the diagnosis and to follow-up information after the initial evaluation period. This paper presents interrater agreement (kappa values) for a diagnosis of Alzheimer's disease using the American Psychiatric Association diagnostic criteria from the Diagnostic and Statistical Manual (DSM-III), the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS) criteria for the clinical diagnosis of Alzheimer's disease, and the Eisdorfer and Cohen Research Diagnostic Criteria (ECRDC) for primary neuronal degeneration. The NINCDS showed somewhat higher average interrater reliability (kappa = 0.64) than the DSM-III (kappa = 0.55) and considerably higher interrater reliability than the ECRDC (kappa = 0.37). One rater displayed conspicuously lower levels of interrater reliability than the other 3, especially in DSM-III and ECRDC. This study indicates that interrater reliability of DSM-III and NINCDS criteria are comparable. Documentation of interrater reliability and, if necessary, training to improve reliability is an important consideration in research where different observers are diagnosing dementing illnesses.

Neuropathological findings in patients with clinical diagnoses of probable Alzheimer's disease.

To assess prospectively the accuracy of standard antemortem clinical diagnostic criteria for Alzheimer's disease, post-mortem examinations were performed on 25 patients who had met DSM-III criteria for primary degenerative dementia and National Institute of Neurological and Communicative Disorders and Stroke criteria for probable Alzheimer's disease. Seventeen patients (68%) met neuropathological criteria for Alzheimer's disease. Two presenile-onset patients had diffuse neocortical senile plaques of insufficient number for definite Alzheimer's disease. Six patients had non-Alzheimer's disease diagnoses. Five of these six had presenile-onset dementia. These results suggest caution in the antemortem diagnosis of Alzheimer's disease in presenile-onset dementia.

Myoclonus, seizures, and paratonia in Alzheimer disease.

Twenty-eight patients with the clinical diagnosis of probable Alzheimer disease (AD) were followed longitudinally until death. The presence of myoclonus, seizures, and paratonia was monitored as part of this process. At autopsy, 22 of the patients met pathologic criteria for AD and 6 had other degenerative neurologic diseases. Myoclonus was present in 55% of the AD patients and none of the non-AD patients. Seizures were present in 64% of the AD patients, and only 17% of the non-AD patients. Paratonia was found frequently in all patient groups. In most patients, symptoms developed late in the course of their illness. The incidence of myoclonus, seizures, and paratonia in our patients was higher than in most previous studies. The reasons for this finding are discussed.

Neuroendocrine responses to physostigmine in Alzheimer's disease.

To assess central nervous system cholinergic neuroendocrine regulation in Alzheimer's disease (AD), we measured plasma arginine vasopressin, beta-endorphin, and epinephrine responses to a cholinergic challenge elicited by intravenous administration of the acetylcholinesterase inhibitor physostigmine (0.0125 mg/kg) in male patients with AD (n = 12) and compared their responses with those of age-matched normal control subjects (n = 12). Physostigmine promptly increased plasma arginine vasopressin (tenfold), beta-endorphin (twofold to threefold) and epinephrine (threefold) levels in elderly control subjects. In contrast, patients with AD showed attenuated responses to physostigmine. When controls and patients with AD who experienced nausea (n = 2 and n = 6, respectively) were excluded, the arginine vasopressin, beta-endorphin, and epinephrine responses of patients with AD were significantly less than those of control subjects. These data suggest that the central nervous system cholinergic deterioration of AD results in decreased responsiveness of neuroendocrine systems that are regulated by central cholinergic mechanisms.

Dexamethasone stimulates thyrotropin-releasing hormone production in a C cell line.

The hypothalamic peptide hormone TRH is also found in other tissues, including the thyroid. While TRH may be regulated by T3 in the hypothalamus, other regulators of TRH have not been identified and the regulation of TRH in nonhypothalamic tissues is unknown. We recently demonstrated the biosynthesis of TRH in the CA77 neoplastic thyroidal C cell line. We studied the regulation of TRH by dexamethasone in this cell line because glucocorticoids have been postulated to inhibit TSH secretion by decreasing TRH in the hypothalamus. Furthermore, TRH in the thyroid inhibits thyroid hormone release. Thus by regulating thyroidal TRH, glucocorticoids could also directly affect thyroid hormone secretion. Treatment of CA77 cells for 4 days with dexamethasone produced dose-dependent increases in both TRH mRNA and cellular and secreted TRH. Increases in TRH mRNA and peptide levels could be seen with 10(-9) M dexamethasone. A 4.8-fold increase in TRH mRNA and a 4-fold increase in secreted peptide were seen with 10(-7) M dexamethasone. Dexamethasone treatment did not increase beta-actin mRNA levels or cell growth. These results suggest that glucocorticoids may be physiological regulators of TRH in normal C cells. In addition to their inhibitory effects on TSH, glucocorticoids may decrease thyroid hormone levels by increasing thyroidal TRH. Since the glucocorticoid effects on C cell TRH are the converse of what is expected for hypothalamic TRH, glucocorticoid effects in these two tissues may be mediated by different regulators.

Pressor, norepinephrine, and pituitary responses to two TRH doses in Alzheimer's disease and normal older men.

Changes in blood pressure (BP), plasma norepinephrine (NE), serum prolactin (PRL), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) associated with infusions of two thyrotropin-releasing hormone (TRH) doses (0.1 mg, 0.5 mg) were examined in 10 men with early-onset Alzheimer's disease (AD) and nine normal matched controls. During the first 5 min after TRH infusion, significant increases from baseline in systolic BP (p less than 0.001), diastolic BP (p less than 0.001), and plasma NE (p less than 0.006) occurred in the study subjects. The magnitude of the BP and NE responses did not differ significantly as a function of TRH dose (p greater than 0.3). Diastolic pressor responses to TRH were substantially blunted in AD subjects relative to controls, after both the 0.1-mg (p less than 0.003) and 0.5-mg (p less than 0.02) doses. There were trends toward attenuated responses in the AD subjects for systolic BP (p less than 0.09) and plasma NE (p less than 0.07). Significant increments in serum PRL, LH, and FSH (all p less than 0.001) also occurred after TRH, but the magnitude of the hormone responses did not differ significantly between the AD and the normal subjects (p greater than 0.18). These results suggest the possibility that TRH-evoked activation of the sympathetic nervous system (SNS), as reflected by pressor and plasma NE responses, may be attenuated in men with early-onset AD.

Characteristics of familial Alzheimer's disease in nine kindreds of Volga German ancestry.

We report the clinical and neuropathological manifestations of Alzheimer's disease (AD) in nine kindreds of German ancestry all originating from the same two adjacent villages on the West bank of the Volga River. There have been 89 known demented persons (53 male, 36 female). Mean age of onset is 57.6 +/- 8.4 years with a range of 40 to 84. Mean age at death is 66.5 +/- 7.6 years with a range of 50 to 80. Mean disease duration is 10.3 +/- 4.8 years with a range of 3 to 23. Detailed medical records were available on 50 individuals. Of these, 24% had a seizure, 72% language disturbance, 36% rigidity, 16% tremor and 12% myoclonus. There were 15 autopsies on demented persons from 6 of the kindreds. One brain suggested Creutzfeldt-Jakob disease (CJD) in a woman with the typical clinical course. The remaining 14 brains showed typical neuropathological characteristics of AD including neuritic amyloid plaques, neurofibrillary tangles, amyloid angiopathy and granulovacuolar change. Amyloid plaques were also seen in the cerebellum in all but one brain in which this region was available for review. Autopsy material from five brains in four families has been stained with antibody directed against the amyloid peptide; in all cases, the neuritic plaques stained positively. Many of the families share common surnames. It is likely that these Volga German kindreds carry the same genetic mutation leading to Alzheimer's disease; and thus, they are a valuable resource for genetic investigations of AD. Thus far, the disease in these kindreds does not show close linkage to either the D21S1 or beta amyloid gene loci on chromosome 21.

Phenotypic heterogeneity in familial Alzheimer's disease: a study of 24 kindreds.

We report the clinical and neuropathological characteristics occurring in 180 demented individuals from 24 kindreds with familial Alzheimer's disease (FAD). Each family had at least two affected generations, and at least one autopsy or brain biopsy was compatible with the diagnosis of AD. Forty-nine neuropathological specimens or reports were reviewed. Mean age of onset for the total group was 54.7 years +/- 11.5, with a large range of 30 to 84 years. Mean age at death was 63.5 years +/- 12.2, with a range of 46 to 85. Mean duration of disease was 8.8 years +/- 4.4, with a range of 1 to 23 years. Six findings suggested phenotypic heterogeneity in FAD. (1) Five families represented an early age of onset group with mean onset at 42 years (range 30 to 51 years) and mean disease duration of 6.7 years. (2) Eight families represented a late onset group with mean onset at 68 years (range 59 to 78 years) and a mean duration of 8.5 years. (3) Seven families were of Volga German ancestry, all originating from the same two villages in Russia. Mean age of onset was 55.9 years (range 40 to 72 years), with a mean disease duration of 10 years. This group probably represents the genetic founder effect of an autosomal dominant gene for AD. (4) One family had the unusual characteristics of neurofibrillary tangles and granulovacuolar change but no amyloid plaques, a mean disease duration of more than 11 years, and a "schizophrenia-like" onset. (5) One family with late onset also had clinical and pathological evidence for anterior horn cell disease. (6) Two autopsies in 1 family both showed remarkable rarefaction of myelin and expansion of perivascular spaces in centrum semiovale (état criblé), with marked leptomeningeal and cortical amyloid angiopathy, distinct from the other FAD brains. It remains to be determined whether the clinical and pathological differences between these families represent genetic heterogeneity at the biochemical or molecular level.

Absence of linkage of chromosome 21q21 markers to familial Alzheimer's disease.

Alzheimer's disease is the most common form of dementia among the elderly population. Although the etiology is unknown, inheritance plays a role in the pathogenesis of the disease. Recent work indicates that an autosomal dominant gene for Alzheimer's disease is located on chromosome 21 at band q21. In the present study of a group of autopsy-documented kindreds, no evidence for linkage was found between familial Alzheimer's disease (FAD) and chromosome 21q21 markers (D21S1/D21S72 and the amyloid beta gene). Linkage to the D21S1/D21S72 locus was excluded at recombination fractions (theta) up to 0.17. Linkage to the amyloid gene was excluded at theta = 0.10. Apparent recombinants were noted in two families for the amyloid gene and in five families for the D21S1/D21S72 locus. These data indicate that FAD is genetically heterogeneous.

Familial Alzheimer's disease in American descendants of the Volga Germans: probable genetic founder effect.

Five families are described in which autopsy-confirmed presenile Alzheimer's disease (AD) has occurred in men and women over multiple generations consistent with autosomal dominant inheritance. All 5 families are descendants of a group of immigrants known as the Volga Germans who came to the United States between 1870 and 1920. Their ancestors moved from Germany to the southern Volga region of Russia in the 1760s. All 5 American families are descendants of persons originally living in two small adjacent Volga German villages and share several surnames known to have been present in the census records of those villages. Although a single affected common ancestor cannot be identified, it is likely that the AD in these families represents an autosomal dominant gene inherited from one ancestor (the founder effect). This information is of importance in the genetic study of AD in these families because it greatly increases the probability of genetic homogeneity. There are more than 300,000 American descendants of the Volga Germans, and the prevalence of AD has never been studied in this population.

TSH responses to two TRH doses in men with Alzheimer's disease.

TSH responses to two TRH doses (0.1 mg, 0.5 mg) were determined in 10 men with Alzheimer's disease (AD) and in nine healthy matched controls. Maximum change in TSH (delta TSH) and TSH responses over time, analyzed independently for each TRH dose, did not reveal any significant differences between the AD and the normal subjects. Blunted delta TSH responses were an uncommon finding in both groups. Analyses examining the influence of TRH dose on TSH responses revealed significant group differences. In normal subjects, delta TSH responses following the 0.5 mg TRH dose were significantly greater than delta TSH responses following the 0.1 mg TRH dose (p less than 0.01). However, in the AD group, the effects of TRH dose on delta TSH were largely attributable to the exaggerated and outlying TSH responses of one AD subject. For the remaining nine AD subjects, delta TSH responses following the 0.1 mg and 0.5 mg TRH doses were not significantly different (p greater than 0.1). In the analysis of TSH responses over time, the difference between the 0.1 mg and the 0.5 mg TRH-induced TSH responses was significantly smaller in the AD group at several timepoints after infusion compared to the normal subjects.