Increased risk of lower limb osteoarthritis among former professional soccer (football) players

BACKGROUND

Soccer is a high-speed contact sport with risk of injury. Despite long-standing concern, evidence to date remains inconsistent as to the association between playing professional-level soccer and lifelong musculoskeletal consequences.

AIMS

The objectives were to assess risk of osteoarthritis in former professional soccer players compared to matched general population controls, and subsequently assess associated musculoskeletal disorders which may contribute to, or result from, osteoarthritis-specifically meniscal injury and joint replacement.

METHODS

We conducted a retrospective cohort study using national electronic health records (EHRs) on a cohort of 7676 former professional soccer players aged 40 or over at recruitment, matched on year of birth, sex (all male) and socio-economic status with 23 028 general population controls. Outcomes of interest were obtained by utilizing individual-level record linkage to EHRs from general hospital inpatient and day-case admissions.

RESULTS

Compared to controls, former soccer players showed a greater risk of hospital admission for osteoarthritis (hazard ratio [HR] 3.01; 95% confidence interval [CI] 2.80-3.25; P < 0.001). This increased risk appeared age dependant, normalizing over age 80 years and reflective of increased risk of lower limb osteoarthritis. Further, risk of hospital admissions for meniscal injury (HR 2.73; 95% CI 2.42-3.08; P < 0.001) and joint replacement (HR 2.82; 95% CI 2.23-3.57; P < 0.001) were greater among former soccer players.

CONCLUSIONS

We report an increased risk of lower limb osteoarthritis in former soccer players when compared with matched population controls. The results of this research add data in support of lower limb osteoarthritis among former soccer players representing a potential industrial injury.

The need for systematic quality controls in implementing N95 reprocessing and sterilization

BACKGROUND

Due to increased requirement for personal protective equipment during the coronavirus disease 2019 pandemic, many medical centres utilized sterilization systems approved under Food and Drug Administration Emergency Use Authorization for single-use N95 mask re-use. However, few studies have examined the real-world clinical challenges and the role of ongoing quality control measures in successful implementation.

AIMS

To demonstrate successful implementation of quality control measures in mask reprocessing, and the importance of continued quality assurance.

METHODS

A prospective quality improvement study was conducted at a tertiary care medical centre. In total, 982 3M 1860 masks and Kimberly-Clark Tecnol PFR95 masks worn by healthcare workers underwent sterilization using a vaporized hydrogen peroxide gas plasma-based reprocessing system. Post-processing qualitative fit testing (QFT) was performed on 265 masks. Mannequin testing at the National Institute for Occupational Safety and Health (NIOSH) laboratory was used to evaluate the impact of repeated sterilization on mask filtration efficacy and fit. A locally designed platform evaluated the filtration efficiency of clinically used and reprocessed masks.

FINDINGS

In total, 255 N95 masks underwent QFT. Of these, 240 masks underwent post-processing analysis: 205 were 3M 1860 masks and 35 were PFR95 masks. Twenty-five (12.2%) of the 3M masks and 10 (28.5%) of the PFR95 masks failed post-processing QFT. Characteristics of the failed masks included mask deformation (N=3, all 3M masks), soiled masks (N=3), weakened elastic bands (N=5, three PFR95 masks), and concern about mask shrinkage (N=3, two 3M masks). NIOSH testing demonstrated that while filter efficiency remained >98% after two cycles, mask strap elasticity decreased by 5.6% after reprocessing.

CONCLUSIONS

This study demonstrated successful quality control implementation for N95 mask disinfection, and highlights the importance of real-world clinical testing beyond laboratory conditions.

The effect of respiratory activity, non-invasive respiratory support and facemasks on aerosol generation and its relevance to COVID-19

Respirable aerosols (< 5 µm in diameter) present a high risk of SARS‐CoV‐2 transmission. Guidelines recommend using aerosol precautions during aerosol‐generating procedures, and droplet (> 5 µm) precautions at other times. However, emerging evidence indicates respiratory activities may be a more important source of aerosols than clinical procedures such as tracheal intubation. We aimed to measure the size, total number and volume of all human aerosols exhaled during respiratory activities and therapies. We used a novel chamber with an optical particle counter sampling at 100 l.min^‐1 to count and size‐fractionate close to all exhaled particles (0.5–25 µm). We compared emissions from ten healthy subjects during six respiratory activities (quiet breathing; talking; shouting; forced expiratory manoeuvres; exercise; and coughing) with three respiratory therapies (high‐flow nasal oxygen and single or dual circuit non‐invasive positive pressure ventilation). Activities were repeated while wearing facemasks. When compared with quiet breathing, exertional respiratory activities increased particle counts 34.6‐fold during talking and 370.8‐fold during coughing (p < 0.001). High‐flow nasal oxygen 60 at l.min^‐1 increased particle counts 2.3‐fold (p = 0.031) during quiet breathing. Single and dual circuit non‐invasive respiratory therapy at 25/10 cm.H₂O with quiet breathing increased counts by 2.6‐fold and 7.8‐fold, respectively (both p < 0.001). During exertional activities, respiratory therapies and facemasks reduced emissions compared with activities alone. Respiratory activities (including exertional breathing and coughing) which mimic respiratory patterns during illness generate substantially more aerosols than non‐invasive respiratory therapies, which conversely can reduce total emissions. We argue the risk of aerosol exposure is underappreciated and warrants widespread, targeted interventions.

One hundred years (and counting) of blast-associated traumatic brain injury

Blast-associated traumatic brain injury (TBI) has become one of the signature issues of modern warfare and is increasingly a concern in the civilian population due to a rise in terrorist attacks. Despite being a recognised feature of combat since the introduction of high explosives in conventional warfare over a century ago, only recently has there been interest in understanding the biology and pathology of blast TBI and the potential long-term consequences. Progress made has been slow and there remain remarkably few robust human neuropathology studies in this field. This article provides a broad overview of the history of blast TBI and reviews the pathology described in the limitedscientific studies found in the literature.

Long-term health outcomes after exposure to repeated concussion in elite level: rugby union players

BACKGROUND

There is continuing concern about effects of concussion in athletes, including risk of the neurodegenerative disease chronic traumatic encephalopathy. However, information on long-term health and wellbeing in former athletes is limited.

METHOD

Outcome after exposure to repeated brain injury was investigated in 52 retired male Scottish international rugby players (RIRP) and 29 male controls who were similar in age and social deprivation. Assessment included history of playing rugby and traumatic brain injury, general and mental health, life stress, concussion symptoms, cognitive function, disability and markers of chronic stress (allostatic load).

RESULTS

The estimated number of concussions in RIRP averaged 14 (median=7; IQR 5-40). Performance was poorer in RIRP than controls on a test of verbal learning (p=0.022) and of fine co-ordination of the dominant hand (p=0.038) and not significantly different on other cognitive tests (p>0.05). There were no significant associations between number of concussions and performance on cognitive tests. Other than a higher incidence of cardiovascular disease in controls, no group differences were detected in general or mental health or estimates of allostatic load. In RIRP, persisting symptoms attributed to concussion were more common if reporting more than nine concussions (p=0.028), although these symptoms were not perceived to affect social or work functioning.

CONCLUSIONS

Despite a high number of concussions in RIRP, differences in mental health, social or work functioning were not found late after injury. Subtle group differences were detected on two cognitive tests, the cause of which is uncertain. Prospective group comparison studies on representative cohorts are required.

Chronic traumatic encephalopathy: a potential late and under recognized consequence of rugby union?

The association between exposure to head injury and increased risk of neurodegenerative disease, specifically chronic traumatic encephalopathy (CTE), is widely recognized. Historically, this was largely considered a phenomenon restricted to boxers, with more recent case series identifying further 'high risk' individuals, such as former American footballers, or military personnel. However, in all cases thus far reported, it is clear that it is the exposure to head injury which is associated with increased dementia risk, and not the circumstances or environment of exposure. As such, there is considerable potential for under-recognition of CTE in patients presenting with neurodegenerative disease, particularly where head injury exposure might have been historical and through sport. This article reviews current understanding of CTE and, via an illustrative case in rugby union, highlights the value of a detailed history on head injury and also draws attention to imaging studies in assessing patients with neurodegenerative disease.

Regional neuropathology referral practice before and after new organ retention legislation

AIMS

Previous organ retention controversies in the United Kingdom have resulted in public concern in relation to the retention of organs following post mortem examination. Therefore, protocols were devised and implemented to facilitate adequate sampling for diagnostic purposes for neuropathology autopsy referrals, without the need for organ retention. We have examined various aspects of referral practice before and after the introduction of these new sampling protocols.

METHODS

All neuropathology autopsy referral cases were reviewed between 1993 and 1995, and 2003 and 2005 and data such as: referral source, nature of samples (whether whole organ or limited sampling) and final diagnosis were recorded.

RESULTS

Overall, the number of autopsy cases referred for neuropathology opinion reduced, particularly those originating from hospital consented autopsies. Forensic referrals also reduced, with a shift in practice from referrals of whole fixed brains, to both whole brains and sampled brain slices. Within the referrals from forensic practice, whilst cases of 'natural deaths' and head injury cases secondary to road traffic accidents or falls reduced, cases involving inflicted, traumatic head injury and sudden unexpected death in epilepsy and infancy remained static.

CONCLUSION

The introduction of protocols to facilitate sampling of brains at autopsy, so minimising organ retention, proved successful and, whilst there has been a reduction in neuropathology referrals, cases in which neuropathology input is deemed best practice remained static.

Hydrodynamic sensing does not facilitate active drag reduction in the golden shiner (Notemigonus crysoleucas)

The lateral line system detects water flow, which allows fish to orient their swimming with respect to hydrodynamic cues. However, it is unclear whether this sense plays a role in the control of propulsion. Hydrodynamic theory suggests that fish could reduce drag by coordinating the motion of the head relative to detected flow signals. To test this hypothesis, we performed measurements of undulatory kinematics during steady swimming in the golden shiner (Notemigonus crysoleucas) at three speeds (4.5, 11.0 and 22.0 cm s−1). We found that the phase shift between yaw angle and lateral velocity (20.5±13.1 deg., N=5) was significantly greater than the theoretical optimum (0 deg.) and the amplitude of these variables created a hydrodynamic index (H=0.05±0.03, N=6) that was less than an order of magnitude below the theoretical prediction. Furthermore, we repeated these measurements after pharmacologically ablating the lateral line hair cells and found that drag reduction was not adversely influenced by disabling the lateral line system. Therefore, flow sensing does not facilitate active drag reduction. However, we discovered that ablating the lateral line causes the envelope of lateral displacement to nearly double at the envelope's most narrow point for swimming at 4.5 cm s−1. Therefore, fish may use hydrodynamic sensing to modulate the lateral amplitude of slow undulatory swimming, which could allow rapid responses to changes in environmental flow.

A case of pilomyxoid astrocytoma presenting with CSF rhinorrhoea in a 15-year-old

We report a pilomyxoid astrocytoma (PMA) presenting with CSF rhinorrhoea in a 15-year-old. This uncommon, recently described entity typically presents in infancy with focal neurological or endocrine symptoms, has distinctive histologic features and displays a more aggressive behaviour than pilocytic astrocytoma (PA) with which it was previously classified.

Gastric carcinoid: germline and somatic mutation of the neurofibromatosis type 1 gene

Neurofibromatosis type 1 (NF1) is one of the most common autosomal dominantly inherited conditions. A range of complications has been described, including gastrointestinal manifestations. Gastric carcinoid tumours are associated with multiple endocrine neoplasia, atrophic gastritis and pernicious anaemia but have not been reported in NF1 in the absence of other predisposing factors. We report the occurrence and investigation of a gastric carcinoid tumour in a 23-year-old woman with previously uncomplicated NF1. Analysis of the tumour tissue revealed loss of heterozygosity at the NF1 gene locus but a normal karyotype and an absence of microsatellite instability. A germline NF1 gene nonsense mutation in exon 37 was detected by denaturing high-performance liquid chromatography and DNA sequence analysis. This is the first reported occurrence of a gastric carcinoid tumour in a patient with NF1 in the absence of other predisposing factors such as pernicious anaemia. The analyses indicate that the carcinoid arose through NF1 gene inactivation but in the absence of an inherited NF1 gene microdeletion. This case adds to the range of gastrointestinal tumours that may be encountered in patients with NF1, particularly in those who present with upper gastrointestinal haemorrhage.

Shortened duration of human chorionic gonadotrophin surveillance following complete or partial hydatidiform mole: evidence for revised protocol of a UK regional trophoblastic disease unit

Following hydatidiform mole, women are at increased risk of persistent gestational trophoblastic neoplasia (pGTN) and are therefore monitored using serum human chorionic gonadotrophin (hCG) concentration measurements. We retrospectively evaluated the policy of extended (2 year) follow up for women with hCG concentrations returning to normal >56 days after evacuation. Of 6701 women registered for hCG follow up, 422 (6%) developed pGTN, 412 (98%) of these women presented within 6 months after evacuation. Three developed pGTN at 402, 677 and 1267 days after evacuation following spontaneous normalisation of hCG levels. Only one woman was detected by routine extended follow up. Prolonged surveillance after molar pregnancy causes significant anxiety and is not cost-effective. Therefore, the current revised protocol comprises hCG follow up for 6 months after spontaneous return of hCG levels to normal for all women.

Non-traumatic forensic neuropathology

The practicing Forensic Pathologist is likely to encounter case material in which either the cause of death or a major contribution to the cause of death is underlying damage to or disease of the central nervous system. While it is good practice in many instances to have a working relationship with a Department of Neuropathology, from which advice and practical help can be sought, there may be instances when the Forensic Pathologist needs to proceed on a basis of a working knowledge of Forensic Neuropathology up to and including how to examine the specimen and take tissue blocks for processing and subsequent histological examination. Some of the more common conditions of the central nervous system such as damage consequent to hypoxia-ischaemia, hypoglycemia and epilepsy, the encephalopathies associated with altered sodium concentration, deficiency due to Vitamin B(1) and various neurodegenerative diseases that manifest as dementia and include Alzheimer's disease, cortical Lewy body disease and the prion disorders, are outlined in this article.

Adenoid cystic carcinoma of the nasal septum

Adenoid cystic carcinoma is a malignant tumour frequently described arising from seromucinous salivary tissue in the major and minor salivary glands. Within the nasal cavity, it is uncommon and usually involves the lateral wall. A rare case of adenoid cystic carcinoma of the nasal septum is presented along with a review of the literature. The presentation and management of this uncommon condition is discussed.

Distribution of and organisation of dorsal horn neuronal cell bodies that possess the muscarinic m2 acetylcholine receptor

Cholinergic systems in the dorsal horn are involved in antinociception but little is known about the organisation of receptors that mediate this process. In this study we examined immunocytochemical properties of dorsal horn neuronal cell bodies that express the m2 muscarinic acetylcholine receptor. Tissue was examined with confocal laser scanning microscopy and quantitative analysis performed. Immunoreactive cells were found throughout the dorsal horn and in lamina X. Quantitative analysis revealed that 22% of neuronal somata in the dorsal horn possess the receptor. The greatest concentration of cells was found in deeper laminae (IV-VI) and around lamina X. A proportion of cholinergic cells (labelled with an antibody against choline acetyltransferase) were immunoreactive for the receptor (approximately, 40% of dorsal horn cells and 44% of lamina X cells). Populations of presumed inhibitory interneurons also displayed immunoreactivity for the receptor. Between 27-34% of cells immunoreactive for GABA, nitric oxide synthase and the somatostatin receptor(2A) expressed the receptor but only 8% of parvalbumin-immunoreactive cells displayed receptor immunoreactivity. Cells labelled with neurotensin, which belong to a subgroup of excitatory neurons, displayed no receptor immunoreactivity. A small number neurokinin-1 receptor-immunoreactive cells in lamina I possessed m2 immunoreactivity but 42% of laminae III/IV neurokinin-1 cells possessed it. This study shows that a significant proportion of cell bodies in the dorsal horn express the muscarinic m2 acetylcholine receptor. The receptor is present on some cholinergic neurons and therefore may function as an autoreceptor. It is associated with inhibitory local circuit neurons and may have a role in the modulation of specific inhibitory systems. It is also found on a proportion of projection cells that possess the neurokinin-1 receptor. This could be the basis of some of the antinociceptive actions of acetylcholine.

HIV Lipodystrophy Case Definition using Artificial Neural Network Modelling

Objective

A case definition of HIV lipodystrophy has recently been developed from a combination of clinical, metabolic and imaging/body composition variables using logistic regression methods. We aimed to evaluate whether artificial neural networks could improve the diagnostic accuracy.

Methods

The database of the case-control Lipodystrophy Case Definition Study was split into 504 subjects (265 with and 239 without lipodystrophy) used for training and 284 independent subjects (152 with and 132 without lipodystrophy) used for validation. Back-propagation neural networks with one or two middle layers were trained and validated. Results were compared against logistic regression models using the same information.

Results

Neural networks using clinical variables only (41 items) achieved consistently superior performance than logistic regression in terms of specificity, overall accuracy and area under the ROC curve. Their average sensitivity and specificity were 72.4 and 71.2%, as compared with 73.0 and 62.9% for logistic regression, respectively (area under the ROC curve, 0.784 vs 0.748). The discriminating performance of the neural networks was largely unaffected when built excluding 13 parameters that patients may not have readily available. The average sensitivity and specificity of the neural networks remained the same when metabolic variables were also considered (total 60 items) without a clear advantage against logistic regression (overall accuracy 71.8%). The performance of networks considering also body composition variables was similar to that of logistic regression (overall accuracy 78.5% for both).

Conclusions

Neural networks may offer a means to improve the discriminating performance for HIV lipodystrophy, when only clinical data are available and a rapid approximate diagnostic decision is needed. In this context, information on metabolic parameters is apparently not helpful in improving the diagnosis of HIV lipodystrophy, unless imaging and body composition studies are also obtained.

Alcohol, tobacco and breast cancer--collaborative reanalysis of individual data from 53 epidemiological studies, including 58,515 women with breast cancer and 95,067 women without the disease

Alcohol and tobacco consumption are closely correlated and published results on their association with breast cancer have not always allowed adequately for confounding between these exposures. Over 80% of the relevant information worldwide on alcohol and tobacco consumption and breast cancer were collated, checked and analysed centrally. Analyses included 58,515 women with invasive breast cancer and 95,067 controls from 53 studies. Relative risks of breast cancer were estimated, after stratifying by study, age, parity and, where appropriate, women's age when their first child was born and consumption of alcohol and tobacco. The average consumption of alcohol reported by controls from developed countries was 6.0 g per day, i.e. about half a unit/drink of alcohol per day, and was greater in ever-smokers than never-smokers, (8.4 g per day and 5.0 g per day, respectively). Compared with women who reported drinking no alcohol, the relative risk of breast cancer was 1.32 (1.19-1.45, P<0.00001) for an intake of 35-44 g per day alcohol, and 1.46 (1.33-1.61, P<0.00001) for >/=45 g per day alcohol. The relative risk of breast cancer increased by 7.1% (95% CI 5.5-8.7%; P<0.00001) for each additional 10 g per day intake of alcohol, i.e. for each extra unit or drink of alcohol consumed on a daily basis. This increase was the same in ever-smokers and never-smokers (7.1% per 10 g per day, P<0.00001, in each group). By contrast, the relationship between smoking and breast cancer was substantially confounded by the effect of alcohol. When analyses were restricted to 22 255 women with breast cancer and 40 832 controls who reported drinking no alcohol, smoking was not associated with breast cancer (compared to never-smokers, relative risk for ever-smokers=1.03, 95% CI 0.98-1.07, and for current smokers=0.99, 0.92-1.05). The results for alcohol and for tobacco did not vary substantially across studies, study designs, or according to 15 personal characteristics of the women; nor were the findings materially confounded by any of these factors. If the observed relationship for alcohol is causal, these results suggest that about 4% of the breast cancers in developed countries are attributable to alcohol. In developing countries, where alcohol consumption among controls averaged only 0.4 g per day, alcohol would have a negligible effect on the incidence of breast cancer. In conclusion, smoking has little or no independent effect on the risk of developing breast cancer; the effect of alcohol on breast cancer needs to be interpreted in the context of its beneficial effects, in moderation, on cardiovascular disease and its harmful effects on cirrhosis and cancers of the mouth, larynx, oesophagus and liver.

Psychometric validation of an overactive bladder symptom and health-related quality of life questionnaire: the OAB-q

OBJECTIVE

Overactive bladder (OAB) is characterized by symptoms of urinary frequency and urgency, with and without incontinence, and has been shown to have significant impact on health-related quality of life (HRQL). Currently, no OAB-specific questionnaires exist to evaluate all symptoms of OAB; thus we sought to evaluate the psychometric properties of a newly developed OAB HRQL questionnaire.

METHODS

The 33-item, self-administered OAB-q contains a symptom bother and HRQL scale. Both the OAB-q and SF-36 were completed by participants from two sources: (1) a community sample who screened positive for OAB in a random-digit dial telephone survey and participated in a clinical validation study (n = 254); and (2) a clinical study of patients' seeking treatment for OAB symptoms (baseline assessment) (n = 736). Item and exploratory factor analysis were performed to assess the subscale structure of the questionnaire. Psychometric evaluation was conducted to assess reliability and validity.

RESULTS

Seventy-four percent of the sample were women with mean age of 58.5. Participants with continent and incontinent symptoms reported significantly greater symptom bother and HRQL impact than normal participants. Significant differences were present among all patient groups in all OAB-q subscales (p < 0.0001) except sleep where the impact of continent and incontinent OAB was similar, but significantly worse than normal participants (p < 0.0001). Internal consistency was high with the subscale Cronbach alpha-values ranging from 0.86 to 0.94.

CONCLUSION

The OAB-q is a reliable and valid instrument that discriminates between normal and clinically diagnosed continent and incontinent OAB participants. The OAB-q demonstrates that both continent and incontinent OAB symptoms cause significant symptom bother and have a negative impact on HRQL.

MOR-1-immunoreactive neurons in the dorsal horn of the rat spinal cord: evidence for nonsynaptic innervation by substance P-containing primary afferents and for selective activation by noxious thermal stimuli

A direct action of mu-opioid agonists on neurons in the spinal dorsal horn is thought to contribute to opiate-induced analgesia. In this study we have investigated neurons that express the mu-opioid receptor MOR-1 in rat spinal cord to provide further evidence about their role in nociceptive processing. MOR-1-immunoreactive cells were largely restricted to lamina II, where they comprised approximately 10% of the neuronal population. The cells received few contacts from nonpeptidergic unmyelinated afferents, but many from substance P-containing afferents. However, electron microscopy revealed that most of these contacts were not associated with synapses. None of the MOR-1 cells in lamina II expressed the neurokinin 1 receptor; however, the mu-selective opioid peptide endomorphin-2 was present in the majority (62-82%) of substance P axons that contacted them. Noxious thermal stimulation of the foot induced c-Fos expression in approximately 15% of MOR-1 cells in the medial third of the ipsilateral dorsal horn at mid-lumbar level. However, following pinching of the foot or intraplantar injection of formalin very few MOR-1 cells expressed c-Fos, and for intraplantar formalin injection this result was not altered significantly by pretreatment with systemic naloxone. Although these findings indicate that at least some of the neurons in lamina II with MOR-1 are activated by noxious thermal stimulation, the results do not support the hypothesis that the cells have a role in transmitting nociceptive information following acute mechanical or chemical noxious stimuli.

Symptoms associated with gastroesophageal reflux disease: development of a questionnaire for use in clinical trials

Many persons who suffer from GERD report additional symptoms, e.g., chest pain, dyspepsia, dysphagia, that are often not measured in clinical trials even though they may be distressing to the GERD sufferer. The primary goal of this study was to develop and assess the psychometric characteristics of a new GERD symptom scale measuring frequency, severity, and distress. The GERD Symptom Assessment Scale (GSAS) was administered to a sample of 169 GERD sufferers at baseline and two weeks. Internal consistency, construct validity, and test-retest reliability were assessed. Responsiveness was evaluated using clinical trial data assessing drug efficacy.

RESULTS

Internal consistency was >0.80 for the symptom severity and distress scales. All three scales showed stability over two weeks (ICC >0.70). Both validity hypotheses were supported. Comparison of effect sizes showed the GSAS is sensitive to changes in severity of symptoms. In conclusion, the GSAS is a reliable, valid, and responsive measure of GERD symptoms.

The prevalence of the neuropathological lesions of Alzheimer's disease is independent of race and gender

Senile plaques (SP) and neurofibrillary tangles (NFT) are the lesions characteristic of Alzheimer's disease (AD). In this study, we examined variation in the proportion of individuals who had these lesions by race, age, and gender in a series of 138 autopsies conducted at the Office of the Chief Medical Examiner of the State of Maryland between 1990 and 1998. Cases were selected on the bases of age between 40 to 79 years and non-natural manner of death, and included 73% males, 61% subjects < 65 years of age, and 42% African Americans. Observations were conducted on histologic sections of the hippocampus, entorhinal cortex, and inferior temporal cortex stained with silver (Hirano method) and immunostained for Abeta-amyloid. We found that SP and NFT are strongly associated with age. These lesions begin to appear in the early to late 40s, depending on the anatomic location, and become common in the 6th decade, preceding by one to two decades the age at which AD becomes clinically prevalent. No difference in the prevalence of SP or NFT was found by gender or between whites and African Americans. The latter is in contrast to epidemiologic studies that suggest AD is more prevalent in African Americans than in whites.

Morphological evidence for selective modulation by serotonin of a subpopulation of dorsal horn cells which possess the neurokinin-1 receptor

Serotonin selectively depresses transmission of nociceptive information through the spinal dorsal horn but the mechanisms of this depression are poorly understood. In this study we report that serotonin-containing axons form basket-like clusters which are intimately woven around cell bodies and proximal dendrites of a subpopulation ( approximately 50%) of laminae III/IV neurons which possess the neurokinin-1 receptor. Statistical analysis confirms that cells belonging to this subpopulation have significantly higher numbers of serotoninergic contacts on proximal dendrites when compared with the population of neurokinin-1 cells that are not associated with clusters (mean +/- SD = 13+/-5.8 and 5+/-2.9, respectively). Neurokinin-1 cells in laminae III/IV project to regions of the brain which are involved in nociceptive processing and are likely to be activated predominantly by nociceptive input. The concentration of serotoninergic axons around proximal regions of some of these cells indicates that serotonin may have a powerful influence on transmission through this pathway. This type of arrangement could be a morphological correlate for at least part of the selective antinociceptive actions of serotonin.