A behavioral comparison of the common laboratory rat strains Lister Hooded,Lewis, Fischer 344 and Wistar in an automated homecage system

Behavioral characterization is an important part of establishing novel animal models, but classical behavioral tests struggle to reveal conclusive results due to problems with both reproducibility and validity. On the contrary, automated homecage observations are believed to produce robust outcomes that relate more to natural animal behavior. However, information on the behavior of background strains from such observations, which could provide important reference material, is rare. For this reason, we compared the behavior of the commonly used Lister Hooded, Lewis, Fischer 344 and Wistar rats during 70 h of exposure to an automated homecage system at 2, 4 and 6 months of age. We found considerable strain differences in metabolic parameters, novelty‐induced and baseline activity‐related behavior as well as differences in the development of these parameters with age. The results are discussed in terms of advantages and disadvantages of the system compared to classical behavioral tests, as well as the system's ability to recreate common findings in literature .     

Family Kinship Patterns and Female Sex Work in the Informal Urban Settlement of Kibera, Nairobi, Kenya

A basic ecological and epidemiological question is why some women enter into commercial sex work while other women in the same socio-economic environment never do. To address this question respondent driven sampling principles were adopted to recruit and collect data for 161 female sex workers and 159 same aged women who never engaged in commercial sex in Kibera, a large informal settlement in Nairobi, Kenya. Univariate analysis indicated that basic kinship measures, including number of family members seen during adolescence and at present, not having a male guardian while growing up, and earlier times of ending relationships with both male and female guardians were associated with commercial sex work in Kibera. Multivariate analysis via logistic regression modeling showed that not having a male guardian during childhood, low education attainment and a small number of family members seen at adolescence were all significant predictors of entering sex work. By far the most important predictor of entering sex work was not having any male guardian, e.g., father, uncle, older brother, etc. during childhood. Results are interpreted in light of the historic pattern of sub-Saharan African child fostering and their relevance for young women in Kibera today.     

Protease gene families in Populus and Arabidopsis

Background  

Proteases play key roles in plants, maintaining strict protein quality control and degrading specific sets of proteins in response to diverse environmental and developmental stimuli. Similarities and differences between the proteases expressed in different species may give valuable insights into their physiological roles and evolution.     

Creatine kinase MB and citrate synthase in type I and type II muscle fibres in trained and untrained men

Total creatine kinase (CK), creatine kinase MB (CK-MB) and citrate synthase (CS) were determined in isolated and pooled type I and type II skeletal muscle fibres. Determinations were made on biopsies from 3 sedentary men, 3 junior cyclists and 2 elite cyclists. CS and CK-MB activities were higher in the trained groups in both fibre types. The total CK activity was not related to training status, although it was lower in type I fibres than in type II fibres (p less than 0.05). The reverse relation was observed for CS and CK-MB activities (p less than 0.01). The ratio of type I/type II for CS was not related to training status, while the corresponding ratio for CK-MB increased with a greater degree of endurance training. For a given increase in CS activity, the increase in CK-MB activity was greater in type I fibres than in type II fibres (p less than 0.01). Thus, with endurance training there seems to be a specific adaptation for CK-MB, particularly in type I fibres.     

Effects of feeding frequency and voluntary salt intake on fluid and electrolyte regulation in athletic horses.

The effect of feeding frequency and voluntary sodium intake (VSI) on fluid shifts and plasma aldosterone concentration (PAC) were studied at rest and after exercise in six athletic horses. The horses were fed twice a day (2TD) and six times a day (6TD) for 25 days for each protocol, according to a changeover design. VSI was measured by weighing each horse's salt block daily. Feeding 2TD or 6TD caused no major alterations in fluid shifts, but in the 2TD treatment there was a postprandial increase in plasma protein concentration and osmolality that lasted <1 h. PAC and VSI were not affected by feeding frequency. VSI ranged from 0 to 62 mg x kg body weight-1 x day-1 and caused significant alterations in PAC. At VSI <26 mg x kg body weight-1 x day-1, a diurnal rhythm for PAC was noted. Water intake, fecal concentrations of sodium and potassium, and packed cell volume during exercise were influenced by VSI. The response to exercise did not differ between treatments. In conclusion, VSI, but not feeding frequency, has significant effects on fluid and electrolyte regulation in athletic horses.     

Regional variation of dissolved organic matter in running waters in central northern Sweden

Regional variations in the concentrations of DOM were studied in running waters in central-northern Sweden. The highest concentrations occurred in the coastal areas, and there was a marked trend with decreasing concentrations towards the inland and the mountain range further west. Explanation of these differences are regional differences in forestland productivity, the occurrence and type of peatlands, annual runoff patterns and soil drainage conditions. Anthropogenic factors, such as atmospheric deposition of acids and forestry, have probably not contributed to the regional differences.     

The many roles of cytochrome b-5 in hepatic microsomes.

The purpose of this report is to review the current literature on cytochrome $\text{b}$₅ in hepatic microsomes and to draw conclusions as to its role in microsomal electron transfer pathways. For details concerning the history of cytochrome $\text{b}$₅ the reader is reffered to reviews by C. F. Strittmatter (1) and P. Strittmatter (2). For information on the chemistry of cytochrome $\text{b}$₅ the reader is reffered to the papers by Ozols and Strittmatter (3), Kajihara and Hagihara (4), and Ehrenberg and Bois-Poltoratsky (5). For more recent studies on the isolation and properties of detergent solubilized cytochrome $\text{b}$₅, which contains a hydrophobic peptide enabling reincorporation into membranes, the reader is referred to references 6-12.For simplicity, this minireview is divided into four parts, reflecting areas of study on the role of cytochrome $\text{b}$₅ in the microsomes. One major area is in fatty acid 9 desaturation. Two other areas concern cytochrome $\text{b}$₅ involvement in cytochrome P-450 mediated mixed function oxidations. The fourth section deals with other non-cytochrome P-450 pathways in which cytochrome $\text{b}$₅ is suggested as being a component.     

Effect of restricted blood flow on exercise-induced hormone changes in healthy men

To test the influence of the accumulation of metabolites on exercise-induced hormone responses, plasma concentrations of cortisol, growth hormone (GH), insulin, testosterone, thyrotropin (TSH), free thyroxine (fT₄) and triiodothyronine (T₃) were compared during exercise performed under normal conditions (control) and under conditions of restricted blood flow of exercising leg muscles (ischaemia) in nine healthy young men. Blood supply was reduced by 15%–20% by the application of 50 mmHg external pressure over the exercising leg. During 45-min cycling exercise during ischaemia the increase in GH concentration was twice as large as under normal conditions. Despite the below-threshold exercise intensity for activation of the pituitary-adrenocortical system under normal exercise conditions ischaemic exercise elicited cortisol and T₃ responses (concentration increases of 83% and 9.5%, respectively). Ischaemic exercise attenuated the decrease of plasma insulin concentration found under normal conditions. The concentrations of testosterone, TSH and fT₄ were not changed significantly during exercise performed in either condition. The results support the suggested essential role of muscle metaboreceptors in the control of hormone responses during muscle activity. Accepted: 6 November 1997