Necrotic enteritis challenge models with broiler chickens raised on litter: evaluation of preconditions, Clostridium perfringens strains and outcome variables

The effect of Clostridium perfringens challenge, number of challenge days, and pre-challenge antibiotic treatment on the induction of necrotic enteritis in broiler chickens raised on litter was studied, and the relationship between bacterial counts and frequency of gut lesions was evaluated. Specific intestinal lesions in randomly selected birds were present despite a lack of disease-specific mortality. Challenge, number of challenge days and frequency of lesions were associated with median counts of C. perfringens. The effect of pre-challenge C. perfringens counts and antibiotics cannot be evaluated unless procedures for the control of pre-challenge infection and methods for the differentiation between wild-type and challenge strains are established.     

Neonatal Treatment With Beta-Cell Stimulatory Agents Reduces the Incidence of Diabetes in BB Rats

The aim of the study was to investigate whether various beta-cell stimulatory drugs, given neonatally, influence the incidence of diabetes in BB rats. Newborn BB rats were treated twice daily for 6 days and diabetes development was observed during the following 200-day study period. Compared to a diabetes incidence of 63.8% in 163 control BB rats which received saline or were untreated, the percentage of experimental BB rats that developed diabetes was as follows in the different subgroups: arginineglucose: 47% (n= 73, p < 0.02); glucagon: 37% (n = 93, p < 0.0001); tolbutamide-glucose: 36% (n = 58, p < 0.0005); and theophylline-glucose: 39% (n = 41, p < 0.005). A long-term arginine-glucose treatment was not superior to the shorter neonatal treatment. Histological examination revealed a higher degree of insulitis in diabetic than in non-diabetic animals but no difference according to the kind of treatment was observed. Finally, we found that the diabetes incidence in BB rats was higher in the first litter compared to subsequent litters (p = 0.04). Thus, neonatal treatment with various beta-cell stimulatory agents reduces diabetes incidence in BB rats. The theory behind the study, that the treatment accelerates beta-cell maturation leading to increased immunological tolerance towards beta cells, is discussed.     

Differential release of prostaglandins by organ cultures of human fetal trachea and lung

Summary Human fetal lung at 16–19 weeks gestation has a partially differentiated epithelium, and in organ culture, distal airsacs dilate and the epithelium autodifferentiates to type I and II pneumatocytes, processes regulated by endogenous prostaglandin PGE₂. Human fetal trachea, at the same gestation, has a terminally differentiated mucociliary epithelium but after 4–6 d in organ culture, develops squamous metaplasia. Tracheal cultures restricted to 3 d have normal phase-contrast and light microscopy appearances and immunohistochemical reactivities (epithelium: cytokeratin 7,8,18; glutathione S-transferase pi-isozyme; epithelial membrane antigen and mesenchyme; desmin; vimentin). In human fetal trachea organ cultures, the predominant prostaglandins released are 6-keto-PGF_1α, PGF_2α, and PGE₂, a pattern similar to that previously described for human adult trachea and lung. In fetal lung cultures, 13,14-dihydro-15-keto-PGF_2α is the major prostaglandin released with lesser amounts of 13,14-dihydro-15-keto-PFG_2α, PGF_2α, PGE₂, and 6-keto-PGF_1α. Human fetal lungin vitro has the competence to self-differentiate, as early as 12 weeks gestation and presence of high levels in fetal lung of the inactive metabolite 13,14-dihydro-15-keto-PGE₂ relative to PGE₂ suggests that active prostaglandin catabolism may be one of the mechanisms to retard this stage of maturationin vivo by limiting PGE₂ availability. Surprisingly, the profile of prostaglandins released from fetal lung organ culture does not change to that of a mature lung with terminal differentiation of the epithelium, and this may indicate differences in the expression of key prostaglandin-metabolizing enzymes in developing human fetal lung in culture and within utero ontogeny.     

Absolute configuration of β,γ-carotene and biosynthetic implications

Racemic γ-ionone, partly resolved via its menthydrazone, was used for total synthesis of β,γ-carotene enriched in the 6′R and 6′S enantiomers. By CD correlation with natural β,γ-carotene isolated from Caloscypha fulgens 6′S-chirality is demonstrated for the natural carotene. Biosynthetic implications regarding the cyclization reaction are discussed.     

Identification by gas-liquid chromatography-mass spectrometry of low-molecular-weight products from the aqueous alkaline degradation of cellulose

Low-molecular-weight products from the degradation of pure cellulose in 0.3–0.65M sodium carbonate or hydrogencarbonate at 300° have been identified by g.l.c-m.s. Both the aqueous residual phase and the floating-oil product phase were examined, and contained essentially the same compounds, which were further characterized by the trifluoroacetyl derivatives. They consisted primarily of unsaturated aliphatic and alicyclic hydrocarbons, aldehydes, ketones, alcohols, and furans. Specifically identified were cyclopentanone, cyclohexanone, phenol, cresols, 2-ethyl- cyclopentanone, 2- or 3-methylcyclopentanone, 2,5-dimethyl-2- cyclopentenone, acrolein, 2,5-dimethyl-2,4-hexadiene, and octene. Probably present were 2,4-dimethylfuran, 2,5-diethylfuran, ethylmethylfuran, 4-octyne, and decyne. The formation of these compounds demonstrates not only the degradation of cellulose but the resynthesis of molecules with carbon-chain lengths greater than 6 atoms.     

A comparison of two different approaches to inventory analysis of dairies

Two different methods for Life Cycle Inventory (LCI) applied to the dairy industry was performed at two dairies. In the simplified method, total environmental loads from a dairy was registred and allocated to liquid milk. Energy and emissions are measured for each process step for the detailed method. Both methods have advantages and disadvantages. The simplified method captures all energy and emissions of dairy processing, but treats the dairy as a “black box”. The energy consumption was found to be 1, 27 MJ/1 and 2,55 MJ/1 for the two dairies. By use of the detailed method it is easy to “loose” information, and it is very time consuming. The energy consumption was lower than for the simplified method. The environmental loads can on the other hand be divided on the different process steps. The main conclusion is that choice of method depends on the purpose of the LCA-study.     

Change in suicide rates for patients with schizophrenia in Denmark, 1981-97: nested case-control study

Objective To study the change in risk of suicide among patients with schizophrenia and related disorders.Design Nested case-control design with linked data.Setting 4 longitudinal Danish registers.Participants 18 744 people aged up to 75 years who committed suicide in 1981-97 individually matched with 20 controls.Results Over the time studied the reduction in suicide rate among patients with schizophrenia and schizophrenia spectrum disorder was similar to that seen in the general population (incidence rate ratio 1.00, 95% confidence interval 0.98 to 1.03). The reduction among patients with other psychosis in the schizophrenia spectrum was faster than the reduction seen in the general population. Among people admitted to hospital with schizophrenia the risk of suicide was highest in the first year after first admission, and the excess risk was largest in the younger age groups—that is, the risk decreased per year for every additional year of age.Conclusion The suicide rate among patients with a diagnosis of schizophrenia and related disorders has fallen. This may be due to better psychiatric treatment, reduced access to means of suicide, or improvements in treatment after suicide attempts.