Seasonal Variation in the Occurrence of Acute Urinary Retention

Objective: To determine whether acute urinary retention shows a seasonal variation. Methods: All acute urinary retentions observed in the emergency room of St. Anna Hospital, Ferrara, along an eight-year period (1991–1998) were considered. Diagnosis was made on the basis of history, physical examination, and bladder drainer by insertion of a catheter with registration of the retained urinary volume. The main determining cause of the acute urinary retention event was tentatively determined. Month and day of each event were categorized both by seasons and monthly intervals. For statistical analysis chi-square test for goodness of fit and partial Fourier series were used. Results: 1,133 acute urinary retention events were observed in 929 different subjects (871 males, 58 females). In 738 cases it was possible to define the main determining cause of the event. The seasonal distribution showed a higher frequency peak of events in summer and autumn both for total population and males subgroup. Analysis by determining cause of the event demonstrated a greater frequency of events in summer only in patients with prostatic hypertrophy. Chronobiologic evaluation showed a circannual pattern for acute urinary retention, both for total sample and male subgroup, with a significant peak in late summer (August–September). Analysis by main determining cause revealed a similar circannual pattern only for cases of acute urinary retention determined by prostatic hypertrophy. Conclusions: The present study shows that acute urinary retention exhibits a circannual distribution in its occurrence, particularly when caused by prostatic hypertrophy.     

Treatment of Urinary Retention

In 50 patients retention of urine due to adenomatous enlargement of the prostate was relieved, in most cases by intraprostatic injections given for varying periods of time. No complications were encountered. Subsequently, some of the patients who did not respond adequately, and whose medical conditions improved, underwent prostateceomy. Histologically the removed prostates showed coagulation necrosis, with or without haemorrhage, but no inflammatory reaction.     

Inter-annual,Annual, and Seasonal Variation of P and N Retention in a Perennial and an Intermittent Stream

Headwater streams represent the key sites of nutrient retention, but little is known about temporal variation in this important process. We used monthly measurements over 2 years to examine variation in retention of soluble reactive phosphorus (SRP) and ammonium (NH₄⁺) in two Mediterranean headwater streams with contrasting hydrological regimes (that is, perennial versus intermittent). Differences in retention between streams were more evident for NH₄⁺, likely due to strong differences in the potential for nitrogen limitation. In both streams, nutrient-retention efficiency was negatively influenced by abrupt discharge changes, whereas gradual seasonal changes in SRP demand were partially controlled by riparian vegetation dynamics through changes in organic matter and light availability. Nutrient concentrations were below saturation in the two streams; however, SRP demand increased relative to NH₄⁺ demand in the intermittent stream as the potential for phosphorus limitation increased (that is, higher dissolved inorganic nitrogen:SRP ratio). Unexpectedly, variability in nutrient retention was not greater in the intermittent stream, suggesting high resilience of biological communities responsible for nutrient uptake. Within-stream variability of all retention metrics, however, increased with increasing time scale. A review of studies addressing temporal variation of nutrient retention at different time scales supports this finding, indicating increasing variability of nutrient retention with concomitant increases in the variability of environmental factors from the diurnal to the inter-annual scale. Overall, this study emphasizes the significance of local climate conditions in regulating nutrient retention and points to potential effects of changes in land use and climate regimes on the functioning of stream ecosystems.     

Seasonal Variation in Pathogenicity of Phytophthora infestans

During a four year study it was shown that the mean lesion area (M.L.A.) developed on leaflets of different potato cultivars by isolates of P. infestans after artificial inoculation varied periodically during the year. Disease symptoms observed changed from pinpoint necroses to regular sporulating lesions depending on the season and the cultivar. Analysis of variance revealed that differences in lesion size between experiments performed in different seasons were significant. The largest M.L.A. was found in late spring or in autumn but autumnal increase of M.L.A. was usually significantly lower than that in spring. Periodicity of M.L.A. was accompanied by a similar phenomenon in sporulation density of P. infestans isolates cultured in vitro. However, the peaks of sporulation, in comparison with peaks of M.L.A. appeared in different seasons. The highest disease level coincided with a decline in sporulation density of P. infestans cultured in vitro and the decrease of M.L.A. corresponded with an increase in sporulation density per cm² of medium. Variation in M.L.A. found in this study seemed not to be related to variability in plant reaction. In this connection a hypothesis has been proposed that the changes of M.L.A. were due to variation in pathogenicity of the fungus.     

Seasonal Variation in Estimates of Cereal-ear Photosynthesis

The potential contribution by ear photosynthesis to yield ofwheat grain was estimated to be greater in summer than winterin glasshouse conditions, and to be light-dependent in controlledenvironment. These results offer an explanation for variationsin published results.     

Seasonal Variation in Sporulation of Phytophthora infestans

Sporulation ability of two isolates of Phytophthora infestans maintained on potato tuber slices of a susceptible cv. ‘Bintje’ and on-rye agar medium was studied for four years (1981–1984). This feature of the fungus was shown to vary in particular seasons during the year. Significantly higher sporulation density per cm² of aerial mycelium on potato tuber slices was observed in winter and late autumn while significantly lower sporulation was found in spring. Similar tendencies were observed when one of the isolates was cultivated on rye agar medium under controlled conditions. Positive correlation was found between sporulation patterns of isolates of the fungus maintained on rye agar and on tuber slices. Hypothesis has been proposed that these changes are due, to a biorhythm in the fungus.     

Seasonal Variation of Nitrogenous Compounds in Components of the Kiwifruit Vine

Free amino acids in 6-year-old kiwifruit vines [Actinidia deliciosa(A. Chev.) C. F. Liang et A. R. Ferguson] were measured overthe course of 1 year using components obtained from whole-vineharvests. Tissues examined from the perennial structure consistedof the wood and cortex of structural roots, wood and bark ofstem, leader and 1-year-old fruiting canes. Free acids in theannual growth (fine roots, flowers, fruit, leaves and non-fruitingshoots) were also measured. The range of amino acids extracted indicated that kiwifruitconforms to a conventional pattern of nitrogen metabolism. Acidspresent in greatest concentration depended on tissue type andsampling time. In perennial components and fine roots, arginineand glutamine were the predominant species, followed by gamma-aminobutyrate,aspartate, glutamate, alanine and valine. Generally, maximumconcentrations of all free acids were measured in a 10-weekperiod around budbreak. These same acids, plus asparagine, serineand threonine, were also prevalent in annual growth. In leaves,flowers and non-fruiting shoots, concentrations were greatestin the young tissue and declined with age. By contrast, concentrationsof arginine, asparagine and glutamine in fruit peaked approximately10 weeks after anthesis, subsequent to the cell division phaseof growth. During the year, free arginine averaged 44, 48 and 58 % of thetotal N in the fine roots, and the cortex and wood of structuralroots, respectively (the quantity of total N and amino-N inother components of the structural framework was much less thanthat in root tissue). Arginine was the principal N-containingspecies measured in xylem sap vacuum-extracted from 1-year-oldcanes over winter. During the period of vegetative growth, however,glutamine and nitrate were the principal N-transport forms present.The study highlights the importance of the fine root systemas the primary location of nitrogenous reserves in this plantand identifies arginine as the dominant N-storage form. Actinidia deliciosa (A. Chev.) C. F. Liang et A. R. Ferguson, amino acid composition, kiwifruit, nitrogen, whole-plant harvesting     

Seasonal Variation in the Structure of a Marine Benthic Microbial Community

Abstract The patterns of seasonal variation in the structure of a marine benthic microbial community were examined using phospholipid fatty acid analysis (PLFA). Principal component analysis of PLFA profiles indicated a strong seasonal pattern dominated the variance within the data set. Three functional groups of microorganisms (phototrophic microeukaryotes, and two groups of anaerobic bacteria) were disproportionately abundant in the communities that mapped to either extreme of the first principle component. Phototrophic microeukaryotes were most abundant and exhibited the greatest relative abundance during periods of cold water. In contrast, the two functional groups of anaerobic bacteria showed the greatest relative abundance during times of warm water. Differential responses by these groups, and macrofaunal deposit feeders, to light intensity and water temperature were offered as the proximal causes of the observed patterns. Received: 28 April 1997; Accepted: 10 September 1997