Flourishing During the COVID-19 Pandemic: A Longitudinal Study in South Africa.

In this longitudinal study, we examine changes in psychological distress and multidimensional well-being from before to during the COVID-19 pandemic among South African adults. As a secondary purpose, we explore whether pre-pandemic flourishing is protective against subsequent psychological distress during the public health crisis. The analytic sample (n = 293; Mage = 44.27, SD = 14.28; female = 65.19%) completed measures of anxiety symptoms, depression symptoms, and well-being shortly before the stringent nationwide lockdown started in South Africa (T1). A follow-up assessment was completed approximately 6 months later (T2). Paired samples t-tests supported very small improvements in anxiety (d = -0.09) and depression symptoms (d = -0.13). For domains of well-being, small increases were found in close social relationships (d = 0.25) and financial and material stability (d = 0.19). Positive changes in the domains of character and virtue (d = 0.10) and meaning and purpose (d = 0.07) were very small. Changes in physical and mental health (d = -0.03) and life satisfaction and happiness (d = 0.02) were more negligible. Results from the generalized linear models indicated that continuous scores of secure flourishing assessed before the COVID-19 pandemic were associated with lower subsequent psychological distress (particularly depression symptoms) during the public health crisis. We discuss the implications of the findings for the development and delivery of interventions to promote and sustain human flourishing during public health crises, especially in contexts of social-structural vulnerability.

[Successful culture of Chlamydia pneumoniae in 2 asymptomatic patients]. / Succesvolle kweek van Chlamydia pneumoniae bij twee asymptomatische patiënten.

In two women, partners of 41 and 36 years old, positive cultures of Chlamydia pneumoniae were repeatedly obtained from the throat. Both individuals were asymptomatic during the period described. Eradication was not achieved despite treatment with doxycycline. C. pneumoniae on the basis of serological data is considered a common cause of respiratory tract infections. However, this micro-organism has only been isolated in the Netherlands once. Carrier status has been described in the literature, although its frequency is unknown.

Ganglion cells in the frog retina: discriminant analysis of histological classes.

Neurons in the ganglion cell layer were studied in Golgi-stained flat-mounted frog (Rana temporaria) retinas. Complementary data were obtained from methylene blue- and HRP-stained retinas. On the basis of qualitative criteria, 55 neurons were ordered into six groups, one class of amacrine cell (A1) and five classes of ganglion cells (G1-G5). A discriminant function analysis based on seven morphological variables resulted in a separation of the cell classes in the space of three axes. The A1 cells are small axonless neurons with knotty and dense dendritic trees. The G1 cells are also small, and apparently very numerous, while the G2 cells are medium-sized neurons with two loose dendritic layers, one vitreal and another (less conspicuous) scleral. The rest of the cells are medium-sized to large neurons with sturdy primary dendrites and more distinct dendritic layers, which in some cells (G3) spread both sclerally and vitreally, in other cells in a single either scleral (G4) or vitreal (G5) layer. The relation between our data and the classification of frog ganglion cells recently presented by Frank and Hollyfield is discussed at length, and in that context problems related to statistical classifications are dealt with. A hypothetical identification of the morphological types with the functional cell classes studied in the Helsinki laboratory is discussed.

Populations of retinal neurones marked with DAPI in lower vertebrates.

Retinae of teleosts, the marine sparid Boops boops and the fresh water cyprinid Carassius auratus, and amphibians, the anuran Rana pipiens and the urodele Ambystoma tigrinum, were stained in vitro with DAPI (4'6-diamidino 2-phenylindole). In all the preparations tested DAPI consistently stained nuclei in the ganglion cell layer, and three levels of nuclei could be observed from IPL (inner plexiform layer) to INL (inner nuclear layer) in the bogue, goldfish and frog retinae. In the goldfish retina a dense mosaic of stained horizontal cell nuclei was also observed. Both single and double cones were stained in fish; no photoreceptor staining could be found in amphibian retinae. Goldfish and frog retinae were incubated with 5'7'-DHT (dihydroxytryptamine) to compare the distribution of DAPI-stained cells with that of putative serotoninergic neurones. Fluorescent cells were found in the ganglion cell layer, and at two levels distally. In fixed retinae only a regular array of cells was found in the proximal INL, and interestingly the cell density equalled the density of serotoninergic amacrine cells. No other fluorescing cells could be detected. In the fixed frog retina two populations of fluorescent cells were found in the INL. For both species tested 5'7'-DHT and DAPI fluorescent populations did not overlap. The images of fluorescent cells were then processed, in order to improve image quality and assess if, in living tissue, cell types could be separated according to differences in intensity of fluorescence. It emerged that the size of fluorescent nuclei is inversely proportional to their optical density.

Formation of new rod photoreceptor synapses onto differentiated bipolar cells in goldfish retina.

In goldfish new rods are continuously added to the entire retina at a rate that assures stable rod density, while the densities of other neurons decrease. The b1 bipolar, known to contact every rod within its dendritic domain, was used to determine the fate of these newly formed rods. Golgi-stained b1 bipolars were sectioned serially at 0.5 micron in the plane of the receptor terminals and reconstructions of their rod and cone contacts were prepared from camera lucida drawings. The newly formed rods are accommodated within the dendritic trees of already-formed b1 bipolars at a rate of about one new rod synapse/bipolar/month. During growth from about 6 months to 5 years of age the number of synapses onto each b1 bipolar increases by 50%. Concomitantly the dendritic tree area increases by about 50%, and the density of rod-b1 synapses remains constant at about one synapse/11 micron 2. Assuming a dendritic coverage factor of 1, the b1 bipolars will contact every retinal rod. The numbers of cones contacted and not contacted do not significantly change. The overall dimensions of b1 bipolars increase with retinal growth and new branches are added to their dendritic trees. These observations show that new rods added to adult goldfish retina form synapses with old bipolars. Some functional inferences are also made.

Neuronal addition and retinal expansion during growth of the crucian carp eye.

Using standard paraffin technique the addition of new cells in crucian carp retinas was examined. Between eye diameters 4.4 and 10.0 mm the number of ganglion cells increases from 103,000 to 205,000, INL cells from 1.5 to 3 million, comes from 250,000 to 900,000, and rods from 2 to 9 million. Concomitantly retinal area increases fivefold and the cell densities decrease by 37% for the cones, 57% for the INL cells, and 58% for the ganglion cells, while the rod density remains stable. In relation to the rods the cell ratios at different retinal loci undergo marked changes during growth. The contributions to retinal growth by addition of new neurons and by expansion of the retina have been determined for the different retinal layers. The layer of rods grows exclusively by addition of new rod mosaic. In the cone layer 81% of growth is due to addition of new cone mosaic. In the inner nuclear layer (INL) 56% of growth is due to addition of new cells and in the ganglion cell layer 52% is due to cell addition. In each case retinal expansion accounts for the remainder of increase in retinal area. On morphological grounds six cone types can be found in the crucian carp retina. Their ratios are constant during retinal growth and at different retinal loci.

Dendritic tree structure and dendritic hypertrophy during growth of the crucian carp eye.

The areas of the ganglion cell dendritic trees were determined in Golgi-stained, flatmounted retinas of crucian carp ranging in age from one summer to 7 years. The dendritic trees of small ganglion cells (S-GC), forming the majority of retinal ganglion cells, add new branches as the retina grows. The increase in dendritic tree area exactly compensates for the decrease in ganglion cell density during growth of the eye so that the number of dendritic trees covering a particular point remains constant. While the retinal diameter increases by a factor of 2.5, the mean diameter of the S-GC dendritic fields increases by a factor of 1.9 and the visual angle covered by one S-GC dendritic tree decreases from 1.6 degrees to 1.2 degrees. The number of branching points of the S-GC dendrites is significantly higher in the ventral retina than in the dorsal. In general the dendrites of the S-GCs tend to grow towards the retinal margin. Dendritic orientation patterns of large (LGC) and large displaced (LDGC) ganglion cells closely resemble those of the amacrines, being oriented parallel to the retinal margin over a wide peripheral region, while the SGCs rapidly lose their tangential orientation. The dendrites of the SGCs are restricted mainly to the proximal sublayer of the inner plexiform layer, suggesting they are ON-cells, while LGC, LDGC, and amacrine cell dendrites are distributed in depth bimodally. As determined from Golgi-stained sections the crucian carp has the same basic IPL organization as the carp and cat.

Retinal ganglion cells in the crucian carp (Carassius carassius). I. Size and number of somata in eyes of different size.

Ganglion cell somata were drawn, measured and counted in flat-mounted crucian carp and goldfish retinas stained with cresyl violet or methylene blue. Some diameter histograms suggest that the ganglion cells can be divided into two populations with overlapping soma sizes: a large group of small cells and a small group of large cells, the latter constituting 2.5-5% of all ganglion cells. With increasing distance from the optic disc the mean soma diameter increases while the ganglion cell density decreases. In a peripheral growth zone close to the margin the ganglion cells become smaller again. The total number of ganglion cells in retinas of different size was calculated from the areas of the flat-mounted preparations and the cell densities in two representative regions. In the crucian carp population used in this work the total number of ganglion cells per retina was found to increase from roughly 140,000 (mean of 8 scattered value) to a full 200,000 between eye diameters 4 and 10 mm, this increase taking place mainly between eye diameters of 4 and 6.5 mm. Thus, due to a drastically decreasing cell density, the total number of ganglion cells increases only by a factor of about 1.5 while the retinal area becomes sixfold. During the same growth period the mean soma diameter increases by a factor of about 1.3 and the soma volume more than doubles. The optic nerve of a small crunated and myelinated axons were found. The axons in the optic nerve are, on an average, considerably thicker than the axons on the retinal surface.

Retinal ganglion cells in the crucian carp (Carassius carassius). II. Overlap, shape and tangential orientation of dendritic trees.

Ganglion cells were studied in methylene blue stained flat-mounted retinas. Three categories of cells are described: small (S) and large (L) ganglion cells in the main ganglion cell layer, and large ganglion cells (LD) with somata more or less displaced into the inner plexiform layer. These LD cells have two to four very thick primary dendrites and are identifiable as ganglion cells by their axons. An analysis of published data reveals that the large ganglion cells of the crucian carp (type L and LD) have several striking characteristics in common with the large ganglion cells of the dogfish, the frog and the cat: (1) they are selectively stained by methylene blue; (2) they comprise only 2-5% of all the ganglion cells; (3) the large cells can be divided into two or three subtypes, and within each subtype the dendritic trees usually cover the retinal surface with a two- or threefold overlap. New ganglion cells are formed from neuroblasts at the retinal margin and most dendrites first grow along this neuroblastic zone. Thus the main dendrites of the L and LD cells tend to be oriented parallel to the margin all around the periphery of a crucian carp retina. Independent of the size of the eye this parallel orientation disappears at the same relative distance from the margin (about one-third of the distance from the margin to the optic disc). If all L and LD cells are formed at the retinal margin and first develop oriented dendrites, we have to assume that the more randomly oriented dendritic trees in the central retina have undergone a reorganization.