AI-aided holographic flow cytometry for label-free identification of ovarian cancer cells in the presence of unbalanced datasets.

Liquid biopsy is a valuable emerging alternative to tissue biopsy with great potential in the noninvasive early diagnostics of cancer. Liquid biopsy based on single cell analysis can be a powerful approach to identify circulating tumor cells (CTCs) in the bloodstream and could provide new opportunities to be implemented in routine screening programs. Since CTCs are very rare, the accurate classification based on high-throughput and highly informative microscopy methods should minimize the false negative rates. Here, we show that holographic flow cytometry is a valuable instrument to obtain quantitative phase-contrast maps as input data for artificial intelligence (AI)-based classifiers. We tackle the problem of discriminating between A2780 ovarian cancer cells and THP1 monocyte cells based on the phase-contrast images obtained in flow cytometry mode. We compare conventional machine learning analysis and deep learning architectures in the non-ideal case of having a dataset with unbalanced populations for the AI training step. The results show the capacity of AI-aided holographic flow cytometry to discriminate between the two cell lines and highlight the important role played by the phase-contrast signature of the cells to guarantee accurate classification.

HCG hastens both the development of mammary carcinoma and the metastatization of HCG/LH and ERBB-2 receptor-positive cells in mice.

Breast cancer is more frequent in human nulliparae, whereas its incidence is reduced by early fullterm pregnancy. Rodent studies suggest that chorionic gonadotropin secretion during pregnancy affords protection by inducing breast structure differentiation. Opposite effects, however, have been observed in cancer prone transgenic mice overexpressing the ß subunit of chorionic gonadotropin or pituitary luteinic hormone (LH). Here we assessed the effect of administration of human chorionic gonadotropin (hCG) for 21 days (corresponding to the duration of a mouse pregnancy) in virgin female mice transgenic for the activated rat (r-) ERBB-2 oncogene (BALB-neuT). In these mice, the onset of atypical mammary duct hyperplasia and its progression towards multiple mammary carcinomas is accelerated by hCG. hCG enhances the in vitro proliferation and in vivo metastatization of tumor cells from a BALB-neuT mammary tumor expressing the hCG/LH as well as the ERBB-2 receptors. These findings suggest that hCG favours the growth and progression of hCG/LH and ERBB-2 receptor-positive breast tumors.

Distribution of cones in human and monkey retina: individual variability and radial asymmetry.

The distribution of photoreceptors is known for only one complete human retina and for the cardinal meridians only in the macaque monkey retina. Cones can be mapped in computer-reconstructed whole mounts of human and monkey retina. A 2.9-fold range in maximum cone density in the foveas of young adult human eyes may contribute to individual differences in acuity. Cone distribution is radially asymmetrical about the fovea in both species, as previously described for the distribution of retinal ganglion cells and for lines of visual isosensitivity. Cone density was greater in the nasal than in the temporal peripheral retina, and this nasotemporal asymmetry was more pronounced in monkey than in human retina.

Serum concentration of homocysteine in spontaneous feline chronic kidney disease.

Serum homocysteine (Hcy) increases in people and dogs with chronic kidney disease (CKD). Hyperhomocysteinemia (HHcy) has also been associated with CKD-related hypertension and proteinuria. The aims of this study were to: (1) validate an enzymatic method for quantification of Hcy in feline serum; (2) evaluate whether HHcy was associated with the presence and severity of CKD, proteinuria or hypertension; and (3) determine whether HHcy could predict disease progression. The intra- and inter-assay coefficients of variation (CVs) and the recovery rates of linearity under dilution and spiking recovery tests of the enzymatic method were 3.1-6.7%, 11.6-12.5%, 96.9±5.4% and 96.9±5.4%, respectively. Healthy cats at risk of CKD (n=17) and cats with CKD (n=19) were sampled over a 6-month period (63 samples in total). Cats with CKD had significantly higher Hcy concentrations (P=0.005) than cats at risk. The concentration of Hcy was higher (P=0.002) in moderate-severe CKD than in mild CKD and correlated moderately with serum creatinine (P<0.0001; r=0.51). The concentration of Hcy increased with the magnitude of proteinuria and correlated weakly with urinary protein to creatinine ratio (P=0.045; r=0.26). HHcy was not associated with hypertension. At the time of enrollment, Hcy concentration was significantly higher (P=0.046) in cats that developed CKD compared to cats that remained stable. The enzymatic method for Hcy measurement in feline serum was precise and accurate. HHcy was relatively common in cats with advanced CKD and seemed to predict disease progression, but further studies are warranted.

Association between High Levels of Parathyroid Hormone and Frailty: The Nepean Osteoporosis and Frailty (NOF) Study.

BACKGROUND: Frailty is associated with poor outcomes hence identification of risks factors is pivotal. Since the independent role of parathyroid hormone (PTH) in frailty remains unexplored, we aimed to determine this in a population of older individuals with a history of falling. DESIGN: Cross-sectional study. SETTING: Falls and Fracture Clinic, Nepean Hospital (Penrith, Australia). PARTICIPANTS: 692 subjects (mean age=79, 65% women) assessed between 2009-2015. MEASUREMENTS: Assessment included clinical examination, mood, nutrition, grip strength, gait velocity, bone densitometry and posturography. Chemistry included serum PTH, calcium, vitamin D (25(OH)D3), creatinine and albumin. Normocalcemic subjects were divided into 4 groups: (1) Normal: 25(OH)D3 >50nmol/L and PTH between 1.6-6.8pmol/L; (2) PTH responsive: low 25(OH)D3 (<50nmol/L) and high PTH (>6.8pmol/L); (3) PTH unresponsive: low 25(OH)D3 and normal PTH; (4) Hyper PTH (>6.8pmol/L) with normal 25(OH)D3. Frailty was defined using Fried's criteria. Difference between the groups was assessed using one-way ANOVA and X2 analysis. Multinomial logistic regression evaluated the association between the groups and the number of Fried's criteria adjusted for age, BMI, renal function, 25(OH)D3 levels, and albumin. RESULTS: 22.6% subjects had high PTH levels (>6.8pmol/L). All subjects in the high PTH groups had significantly lower grip strength, gait velocity, limits of stability, and higher BMI. The PTH responsive group had a higher risk of pre-frailty (ß=3.8, 95% CI = 3.42 - 5.22, p≷ 0.01) and frailty (ß=8.26, 95% CI = 2.8-16.1, p<0.01). The risk of frailty was also higher in the Hyper PTH group (ß=2.3, 95% CI = 1.74-4.32, p<0.01). CONCLUSION: We have reported an independent association of high PTH levels with high number of falls and with the clinical components of physical frailty in community dwelling older persons. Our results suggest a possible role of PTH in frailty that deserves further exploration.

Abdominal Obesity and Mobility Disability in Older Adults: A 4-Year Follow-Up the International Mobility in Aging Study.

BACKGROUND: Abdominal obesity is related to the disability process in older adults, however, little is known about this relationship when adjusted for important confounders such as depression and physical performance measures in a diverse international aged population. OBJECTIVES: To explore the longitudinal relationship between abdominal obesity and mobility disability controlling for physical performance and depression. DESIGN AND SETTING: Longitudinal observational study using data from the International Mobility in Aging Study (IMIAS) Study. PARTICIPANTS: 1104 out of 2002 older adults aged 64-74 years old free of mobility disability at baseline (2012) and then reassessed in 2016. MEASUREMENTS: Mobility disability was defined as reporting difficulty in walking 400 m or climbing stairs. Activities of daily living (ADL) disability was based on any self-reported difficulty in five mobility-related ADLs. Abdominal obesity was defined as waist circumference ≥ 88cm for women or ≥ 102 cm for men. Four meters gait speed, handgrip strength and depressive symptoms (CES-D) were assessed. Generalized Estimating Equations (GEE) and multinomial regressions were used to estimate associations between disability and abdominal obesity. RESULTS: 1104 free of disability participants were followed over 4 years, the mean age was 68.9 (±2.9) years among men and 68.7 (±2.6) years among women. Prevalence and incidence rates of mobility disability varied widely across research site and sex. The longitudinal associations between mobility disability and abdominal obesity remained significant even when adjusted by depressive symptoms, handgrip strength, gait speed, age, sex, education and research site. Participants with abdominal obesity had higher mobility disability (OR=1.68, 95% CI 1.23-1.76, p-value=0.01) and also increased risk for ADL disability (OR: 1.47, 95% CI 1.23-1.76, p-value=0.01). Abdominal obesity in baseline was also predictor of mobility disability in 2016 (OR: 1.93, 95% CI 1.17-3.17, p-value <0.01) but not for ADL disability (OR: 1.59, 95% CI 0.93-2.71, p-value =0.09) with accounting mortality. CONCLUSION: Abdominal obesity is associated longitudinally and predicts mobility disability, even over a short period (4 years) in community-dwelling older adults from different epidemiological contexts.

FAM49B, a novel regulator of mitochondrial function and integrity that suppresses tumor metastasis.

Mitochondrial dysregulation plays a central role in cancers and drives reactive oxygen species (ROS)-dependent tumor progression. We investigated the pro-tumoral roles of mitochondrial dynamics and altered intracellular ROS levels in pancreatic ductal adenocarcinoma (PDAC). We identified 'family with sequence similarity 49 member B' (FAM49B) as a mitochondria-localized protein that regulates mitochondrial fission and cancer progression. Silencing FAM49B in PDAC cells resulted in increased fission and mitochondrial ROS generation, which enhanced PDAC cell proliferation and invasion. Notably, FAM49B expression levels in PDAC cells were downregulated by the tumor microenvironment. Overall, the results of this study show that FAM49B acts as a suppressor of cancer cell proliferation and invasion in PDAC by regulating tumor mitochondrial redox reactions and metabolism.

Plasma apolipoproteins and risk for age related maculopathy.

AIM: To determine if elevated plasma levels of atherogenic and/or anti-atherogenic lipoproteins are risk factors for developing age related maculopathy (ARM). METHODS: In a cross sectional study in a university clinic setting, 129 patients (72 women and 57 men) underwent colour fundus photography, acuity and contrast sensitivity assessment, and electroimmunoassays of plasma apolipoproteins B (apoB) and A-I (apoA-I), the principal proteins of low density and high density lipoproteins, respectively. Maculopathy stage was assigned using the AREDS grading system. RESULTS: Levels of apoB in no ARM, mild, intermediate, and advanced ARM groups were 93.3, 91.8, 95.2, and 98.2 mg/dl, respectively. Levels of apoA-I were 147.4, 148.6, 141.0, and 144.9 mg/dl in the same groups. There was no significant association between these measures, typical for age, and maculopathy stage. CONCLUSION: Although drusen associated with ARM and ageing contain cholesterol and apoB, like the lipid rich core of an atherosclerotic plaque, the results of this study and our previous work in toto make the prospects of a plasma origin for these lesion constituents increasingly untenable. This conclusion is consistent with an emerging hypothesis that a large lipoprotein of intraocular origin is an important pathway for constituent retinal lipid processing and the biogenesis of drusen.

Specific blastogenic response of peripheral blood lymphocytes from lung cancer patients to a fetal lung antigen.

A human lung tumor fetal-associated antigen (LTFA) has been purified from lung tumor tissue by a combination of salt precipitation and ion-exchange chromatography. The purification steps were monitored by double immunodiffusion with the use of a rabbit anti-LTFA-specific antiserum. The isolated protein was tested for its blastogenic properties toward peripheral blood lymphocytes (PBL) by [3H]thymidine incorporation. PBL obtained from 25 healthy individuals, 34 patients with tumors other than lung tumors, 13 patients with lung diseases other than lung tumors, and 51 lung tumor-bearing patients were tested. Only PBL with an in vitro positive response to phytohemagglutinin were employed. Whereas PBL of lung tumor patients showed a significant blastogenic response to the purified antigen in 14 of 22 patients tested (60%), PBL of other patients were completely unreactive (P less than 0.005). The present data suggested that a specific immune response toward an LTFA was present in patients with lung cancers.

Carboplatin plus vinorelbine, a new well-tolerated and active regimen for the treatment of extensive-stage small-cell lung cancer: a phase II study. Gruppo Oncologico Centro-Sud-Isole.

PURPOSE: To evaluate the activity and toxicity of the combination carboplatin plus vinorelbine in extensive small-cell lung cancer (SCLC). PATIENTS AND METHODS: A two-stage optimal Simon design was applied. To proceed after the first stage, responses from 8 of 11 treated patients were needed. Overall, 31 responses of 43 treated patients were required to comply with the design parameters. Inclusion criteria were cytohistologically proven SCLC; extensive disease; age of 70 years or less; Eastern Cooperative Oncology group performance status (ps ECOG) of 2 or less; normal cardiac, hepatic, renal, and bone marrow functions; and no previous chemotherapy. Patients were staged by physical examination; biochemistry; chest radiograph; brain, thoracic; and abdominal computed tomographic (CT) scans, and bone scan. All patients received carboplatin 300 mg/m2 intravenously (i.v.) day 1 and vinorelbine 25 mg/m2 i.v. on days 1 and 8 every 4 weeks up to six cycles. Of 43 enrolled patients, 36 were men and 7 women, with a median age of 63 years (range, 46 to 70 years). RESULTS: All patients were assessable for response and toxicity. We observed 32 (74%) objective responses, with 23% complete responses. Median time to progression was 25 weeks, and median survival was 37 weeks. The treatment was well tolerated. The reported main toxicities were leukopenia grade 3 in 21% of patients and grade 4 in 5% of patients, anemia grade 2 in 11% of patients and grade 3 in 2% of patients, and thrombocytopenia grade 3 in 7% of patients. CONCLUSION: These data show that carboplatin plus vinorelbine is an active and well-tolerated regimen in extensive SCLC. In view of the activity, low toxicity, and ease of administration, it may be a reasonable alternative to more toxic cisplatin-containing regimens.

Comprehensive nutritional status in sarco-osteoporotic older fallers.

OBJECTIVES: In older persons, the combination of osteoporosis and sarcopenia has been proposed as a subset of frailer individuals at higher risk of falls and fractures. However, the particular nutritional status of the sarco-osteoporotic (SOP) patients remains unknown. The goal of this study was to obtain a comprehensive picture of nutritional status in SOP patients. DESIGN: Cross-sectional study. SETTING: Falls and Fractures Clinic, Nepean Hospital (Penrith, Australia). PARTICIPANTS: 680 subjects (mean age=79, 65% female) assessed between 2008-2013. MEASUREMENTS: Assessment included medical history, mini-nutritional assessment, physical examination, bone densitometry and body composition by DXA, and blood tests for nutritional status (albumin, creatinine, hemoglobin, vitamin D, vitamin B-12, calcium, phosphate and folate). Patients were divided in 4 groups: 1) osteopenia/osteoporosis (BMD<-1.0 SD); 2) sarcopenia; 3) SOP; and 4) normal (no sarcopenia/no osteoporosis). Difference between groups was assessed with one-way ANOVA and chi square analysis. Multivariable linear regression evaluated the association between the groups and measures of nutritional parameters. RESULTS: Sarcopenia was present in 47.4% of those with osteopenia (167/352) and 62.7% in those with osteoporosis (91/145). Mean age of the SOP was 80.4±7 years. SOP patients showed significantly higher prevalence of falls and fractures. Univariate analyses showed that SOP were more likely than normal to have a BMI< 25 (OR 2.42 95%CI 1.45-4.041, p<0.001), a MNA score <12 (OR 2.0, 95%CI 1.15-3.49, p<0.05), serum folate <20 nmol/L (OR 4.0 95%CI 1.35-11.87, p<0.01) and hemoglobin <120g/L (OR 2.0 95%CI 1.28-3.30, p<0.01). Multivariate analysis showed that a MNA score <12 was independently associated with SOP compared to normal when adjusted for age and gender. Hemoglobin <120g/L, BMI <25, and GDS >6 remained independently associated with SOP after adjustment for all variables including inflammatory conditions. Hypoalbuminemia (<35 g/L) was associated with just osteopenia/osteoporosis (OR: 2.03, 95%CI 1.08-3.81, p<0.01) and just sarcopenia (OR: 1.77, 95%CI 1.0-3.0, p<0.01) compared to normal. No differences in vitamin D, glomerular filtration rate, albumin, corrected calcium, phosphate, red blood cells folate or vitamin B12 levels were found between the subgroups. CONCLUSIONS: In approaching SOP patients, early prevention protocols directed to optimize their nutritional status would be a key strategy to prevent poor outcomes such as falls and fractures in this high risk population. Therefore, nutritional assessment and early nutritional supplementation should be essential domains in this strategy.

Nucleus raphe dorsalis in dementia of the Alzheimer type: neurofibrillary changes and neuronal packing density.

Within the reticulate core of the brain the nucleus raphe dorsalis (NRD) is a major site of predilection for the neurofibrillary tangle (NFT) in dementia of the Alzheimer type (DAT) and, according to some studies, its primary brain stem site. In a quantitative study we have shown in six aged control brains an average of 5.2 NFT per histological section or 25.8 per mm3 and in seven age-matched brains with DAT a highly significant six-fold increase, respectively 35.3 NFT per histological section or 188.5 per mm3. There was no significant difference between the two groups in overall neuronal cell packing density. There was, however, a significant decrease in a subpopulation of neurons in DAT, a large polygonal neuron. Despite the prominence of the NRD as a target for NFT, the actual proportion of affected NRD cells was small, 0.35% in controls and 2.25% in DAT.

Development of compensatory thermogenesis in response to overfeeding in hypothyroid rats.

Intact or surgically thyroidectomized (Tx) adult male Wistar rats, weighing 150-200 g, were fed a standard chow diet (approximately 1.8 Cal/g) or a high calorie (approximately 3.8 Cal/g) diet (cafeteria diet) for up to 30 days. Daily energy intake was about 5-fold higher in the rats fed the cafeteria diet regardless of their thyroid status. The cafeteria diet caused the retroperitoneal white fat pad to increase by approximately 2-fold, the volume of isolated white adipocytes to increase by 2-fold, and the total body fat to increase by a factor of approximately 3, again regardless of thyroid status. It also increased basal metabolic rate by about 20% in intact rats and by about 50% in Tx rats. The brown fat thermal response to norepinephrine (NE) infusion was approximately 2-fold increased in the intact rats fed the cafeteria diet. However, in the Tx rats, the brown fat thermal response to NE was blunted regardless of the dietary regimen adopted. In both intact and Tx rats, the cafeteria diet increased total brown fat mitochondria, uncoupling protein percentage, and total brown fat uncoupling protein by about 3-, 2-, and 5-fold, respectively. Serum leptin levels also increased approximately 4-fold in intact rats fed the cafeteria diet. However, in Tx rats, leptin levels did not change significantly during overfeeding. In conclusion, hypothyroidism caused the brown fat to become unresponsive to NE, even after 1 month on the cafeteria diet. However, these rats were able to increase basal metabolic rate and, as assessed by several different parameters, did not gain fat beyond that observed in intact controls kept on a similar overfeeding schedule.

Stability of synaptic density and spine volume in dentate gyrus of aged rats.

The number of synapses per unit volume and per granule cell and the size of dendritic spines were studied in the dentate gyrus of Sprague-Dawley rats 6, 24, and 30 months of age. Neither synaptic density nor mean spine volume showed any age-related trends. An increase in granule cell packing density at 24 months and concomitant stability of the height of the granule cell layer is consistent with the idea that postnatal generation of granule cells may continue late into life. Possible explanations for the discrepancies in the literature regarding synaptic loss in this area include differences in morphometric techniques, age of animals used, regional differences within dentate gyrus, and sampling variability. Generalized synapse loss in the senescent rodent brain remains to be established.

Stability of dendrites in cortical barrels of C57BL/6N mice between 4 and 45 months.

Qualitative and quantitative studies of dendritic parameters were conducted on Golgi-impregnated layer IV spiny stellate neurons in the posteromedial barrel subfield (PMBSF) of somatosensory cortex of the C57B1/6N mouse. Three mice each, at 4, 12, 22, 26, 30, 36 and 45 months of age were studied. No qualitative changes were observed among animals of different ages. The quantitative data indicated that dendritic length and numbers of segments remained unchanged over all ages studied.

Stability of neuron number in cortical barrels of aging mice.

The question of whether age-related neuron loss occurs in the cerebral cortex of rodents, as it apparently does in humans, has not been directly answered by previous studies. The barrel, a discrete morphological and functional unit in rodent somatosensory cortex, is a favorable system in which to address the problem of neuron loss during senescence. The numerical density and absolute number of neurons as well as barrel volume were determined from a computer-assisted three-dimensional reconstruction of thick (100 microns) and semithin (1 micron) sections through a single barrel, C3, from inbred mice (C57Bl/6NNia) at 4, 12, 22, 26, 30, and 33 months of age. The number and density of neuron and glial cells and the volume of the barrel did not change significantly with age. These data indicate that neuron loss is not a universal phenomenon in senescence and that there may be significant species differences in the aging of laboratory rodents and humans.

Topography of ganglion cells in human retina.

We quantified the spatial distribution of presumed ganglion cells and displaced amacrine cells in unstained whole mounts of six young normal human retinas whose photoreceptor distributions had previously been characterized. Cells with large somata compared to their nuclei were considered ganglion cells; cells with small somata relative to their nuclei were considered displaced amacrine cells. Within the central area, ganglion cell densities reach 32,000-38,000 cells/mm2 in a horizontally oriented elliptical ring 0.4-2.0 mm from the foveal center. In peripheral retina, densities in nasal retina exceed those at corresponding eccentricities in temporal retina by more than 300%; superior exceeds inferior by 60%. Displaced amacrine cells represented 3% of the total cells in central retina and nearly 80% in the far periphery. A twofold range in the total number of ganglion cells (0.7 to 1.5 million) was largely explained by a similar range in ganglion cell density in different eyes. Cone and ganglion cell number were not correlated, and the overall cone:ganglion cell ratio ranged from 2.9 to 7.5 in different eyes. Peripheral cones and ganglion cells have different topographies, thus suggesting meridianal differences in convergence onto individual ganglion cells. Low convergence of foveal cones onto individual ganglion cells is an important mechanism for preserving high resolution at later stages of neural processing. Our improved estimates for the density of central ganglion cells allowed us to ask whether there are enough ganglion cells for each cone at the foveal center to have a direct line to the brain. Our calculations indicate that 1) there are so many ganglion cells relative to cones that a ratio of only one ganglion cell per foveal cone would require fibers of Henle radiating toward rather than away from the foveal center; and 2) like the macaque, the human retina may have enough ganglion cells to transmit the information afforded by closely spaced foveal cones to both ON- and OFF-channels. Comparison of ganglion cell topography with the visual field representation in V1 reveals similarities consistent with the idea that cortical magnification is proportional to ganglion cell density throughout the visual field.

Development redistribution of photoreceptors across the Macaca nemestrina (pigtail macaque) retina.

Redistributions of monkey cones and rods during the first year after birth include a fivefold increase in peak foveal cone density from 43,000 to 210,000 cones/mm2, a decrease in the diameter of the rod-sparse area, and a two- to threefold decrease in peripheral photoreceptor density. Two weeks before birth, higher cone density is already apparent in the future fovea, as are the nasotemporal asymmetry in cone distribution, a higher density "cone streak" along the horizontal meridian, a large rod-sparse central fovea, and a ring of high rod density. Despite the early appearance of these basic patterns, photoreceptor distribution is not mature until 1 to 5 years postnatally. Total cones varied from 4 million at birth to 3.1 million in the average adult. The two oldest eyes had fewer cones, suggesting up to a 25% loss late in development. There were 60 to 70 million rods in the adult macaque retina and little evidence of postnatal changes in number. Neither of these small changes is sufficient to account for the reduction in peripheral photoreceptor density and both are in the wrong direction to explain increasing foveal density, ruling out a major role for either photoreceptor death or generation. Retinal area increased by a factor of 2.4 from 2 weeks before birth to adulthood. In contrast, the posterior pole of the retina was dimensionally stable throughout this period, with the distance between the fovea and optic disc varying nonsystematically from 3.37 to 4.05 mm. Retinal coverage of the globe was also stable at 48-60%. Thus postnatal growth can be ruled out as a factor in the density changes occurring in central retina. Adult retinas have a higher proportion of both cones and rods in midperiphery, whereas young retinas have a higher proportion of photoreceptors in far periphery. It appears that photoreceptors are radially redistributed from peripheral toward central retina during postnatal development, resulting in the marked increase in foveal cone density and the decrease in the eccentricity of the rod ring. Up to 13 weeks postnatally, midperipheral growth of the retina is substantial and increases with eccentricity. At later ages, expansion continues only in the very far periphery. Retinal growth appears sufficient to explain the decreases in peripheral rod and cone density with age. These and previous data strongly suggest that differentiated photoreceptors, with complex cytology and synaptic contacts, migrate toward the foveal center, explaining the increase in foveal photoreceptor density.(ABSTRACT TRUNCATED AT 400 WORDS)

Photoreceptor topography of the retina in the adult pigtail macaque (Macaca nemestrina).

In spite of the crucial role retinal photoreceptors play in mapping optical images into a pattern of neural excitation, there are no complete studies of photoreceptor topography in any primate retina. We have measured the spatial density and inner segment areas of cones and rods across the whole mounted retinas of three adult pigtail macaques (Macaca nemestrina) and constructed maps of photoreceptor density and inner segment diameter. These retinas contain an average of 3.1 million cones (2.8-3.3 million), with an average peak foveal cone density of 210,000 cones/mm2 (190,000-260,000 cones/mm2). Cone density falls steeply with increasing eccentricity, to 100,000 cones/mm2 at 200 microns from the fovea, and to 50,000 cones/mm2 at 750 microns. Imposed on this gradient is a "streak" of higher cone density along the horizontal meridian. At equivalent eccentricities, cone density is higher in nasal and inferior retina. Cone inner segments increase in diameter from 2.3 microns at the foveal center to 11 microns in far temporal retina and 10 microns in far nasal retina. These retinas contain an average of 60.1 million rods (44.9-75.3 million). Rod density is zero within 20 microns of the foveal center, increases to the crest of a "rod ring" at the eccentricity of the optic disk, and then declines. Central rod topography is asymmetric, with higher densities in superior retina. Density along the crest of the rod ring peaks in superior retina at 177,000 rods/mm2, dips as low as 120,000 rods/mm2 along the horizontal meridian, and increases to about 150,000 rods/mm2 in inferior retina. Far peripheral rod topography is relatively symmetric around the fovea. Rod inner segment diameter ranged from 1.5 microns in the fovea to 4 microns at the temporal edge and 3.4 microns at the nasal edge of the retina. At eccentricities exceeding 6 mm, rod inner segment diameter was greater temporally than nasally. Cone inner segments cover 85-90% of the central fovea, with extrareceptor space accounting for the remainder. Cone coverage declines with increasing eccentricity to 20% at the temporal edge and 35% at the nasal edge of the retina. In contrast, rod coverage increases from zero at the foveal center to a maximum of 65% in temporal retina and 50% in nasal retina. The photoreceptor topography of the pigtail macaque is qualitatively similar to that of other macaques and to humans. Photoreceptor topography is formed by a complex interaction between regional changes in cone and rod density and inner segment diameter.

Aging in the rat olfactory system: relative stability of piriform cortex contrasts with changes in olfactory bulb and olfactory epithelium.

Previous studies have quantified growth and atrophy of the olfactory bulb and olfactory epithelium of the Sprague-Dawley rat from maturity to senescence. Major events occurring in these structures include changes in the volume of mitral cells and changes in the number of septal olfactory receptors. These effects are large, consist of a growth phase followed by atrophy, and are temporally related in that events in the olfactory epithelium precede those in the mitral cells. A hypothesis of aging based on transneuronal effects would predict that these changes would be similarly transmitted to the next synaptic station in the olfactory pathway. Therefore, cells and synapses of the piriform cortex were studied in rats 3, 12, 18, 24, 27, 30, and 33 months of age. Alternate Vibratome sections through brains perfused with mixed aldehydes were processed for light and electron microscopy. No significant age effects were found for the volumes of cortical laminae Ia and Ib. Both numerical and surface density of synaptic apposition zones in layer Ia, formed primarily by mitral cell axons, were stable with age. A modest (18%) but significant decline in the proportion of layer Ia occupied by dendrites and spines was mirrored by an increase in the proportion of glial processes; no change in the proportion of axons and terminals was observed. Neither nuclear volume, nor soma volume, nor numerical density of layer II neurons changed with age. Thus, contacts made in the piriform cortex by mitral cell axons remain relatively stable in senescence, despite the marked volumetric changes in the mitral cell somata, changes which were confirmed again in this study. Age-related dendritic regression in layer II neurons may be attributable to functional deafferentation subsequent to reduced receptor input to mitral cells.