Hormone-sensitive lipase is structurally related to acetylcholinesterase, bile salt-stimulated lipase, and several fungal lipases. Building of a three-dimensional model for the catalytic domain of hormone-sensitive lipase

Hormone-sensitive lipase is the key enzyme in the mobilization of fatty acids from adipose tissue, thereby playing a crucial role in the overall energy homeostasis in mammals. Its activity is stimulated by catecholamines through cAMP-dependent phosphorylation of a single serine, a process that is prevented by insulin. This regulatory property is unique to this enzyme among all known lipases and has been acquired during evolution through insertion of a regulatory module into an ancestral lipase. Sequence alignments have failed to detect significant homology between hormone-sensitive lipase and the rest of the mammalian lipases and esterases, to which this enzyme is only very distantly related. In the present work, we report the finding of a remarkable secondary structure homology between hormone-sensitive lipase and the enzymes from a superfamily of esterases and lipases that includes acetylcholinesterase, bile salt-stimulated lipase, and several fungal lipases. This finding, based on the identification of the secondary structure elements in the hormone-sensitive lipase sequence, has allowed us to construct a three-dimensional model for the catalytic domain of hormone-sensitive lipase. The model reveals the topological organization, predicts the components of the catalytic triad, suggests a three-dimensional localization of the regulatory module, and provides a valuable tool for the future study of structural and functional aspects of this metabolically important enzyme.     

Gliadin-specific and cow''s milk protein-specific IgA in human milk

The presence of gliadin-specific IgA and IgG antibodies in colostrum and serum of 140 newly delivered mothers was assessed by enzyme-linked immunosorbent assay. In addition, cow's milk protein (CMP)-specific IgA was determined in the colostrum samples. From 14 of the mothers longitudinal milk samples were obtained after 1 and 2 months of lactation and from 12 mothers after 3 months. Gliadin-specific IgA was found in 97.1% and gliadin-specific IgG in 9.3% of the colostrum samples. Gliadin-specific IgA was detected in mature samples but at significantly lower levels after 1, 2, and 3 months of lactation (p less than 0.01) as compared with colostrum. Gliadin-specific IgA was found in 2.8% of the serum samples and gliadin-specific IgG in 40%; however, the levels of both isotypes were low. CMP-specific IgA was found in 78.1% of the colostrum samples. It is concluded that IgA antibodies to two common food proteins are frequently found in human milk and that food-specific IgA present in milk may play a role in adapting the infant's immune reactions to food antigens in the gut.     

Epidemiological and clinical aspects of invasive group A streptococcal infections and the streptococcal toxic shock syndrome

In a retrospective study of invasive infections due to group A Streptococcus (GAS) in Stockholm during 1987 to 1995, the average incidence per 100,000 residents per year was 2.3, varying between 3.7 per 100,000 (in 1988) and 1.3 per 100,000 (in 1993). Incidence was 1.8 in the age group of 0-4 years but otherwise increased by age, from 0.48 in the age group of 5-14 years to 6.1 among those over 65 years of age. A review of 151 invasive episodes occurring in 1983-1995 showed cyclic increases of infections due to T1M1-serotype strains during 1986-1990 and 1993-1995. The T1M1 serotype accounted for 27 (20%) of 135 available GAS strains. Streptococcal toxic shock syndrome (STSS) developed in 19 (13%) of the 151 episodes. The case fatality rate was 11% overall but 47% among patients with STSS. In a multivariate logistic regression model, STSS was associated with a history of alcohol abuse (odds ratio [OR], 6.3; P = .004) and infection with a T1M1 strain (OR, 6.7; P = .007). Case fatality was associated with age (OR, 14.5; P = .08), immunosuppression (OR, 4.7; P = .02), and STSS (OR, 21.5; P < .0001) but not with T1M1 infection. Hypotension was significantly associated with a fatal outcome, regardless of whether STSS developed (P < .0001).     

Counteraction of pitting in copper water pipes by bicarbonate dosing

Copper pipes are extensively used for tap water installations and generally perform well. Exceptionally, however, copper pipes are perforated due to pitting. Three main types of pitting (I, II and III) have been identified, but as for the causes and the mechanisms these have not yet been fully clarified. Through case studies, model experiments, thermodynamic calculations, and service tests, evidence has been obtained that waters having a pitting propensity for copper pipes can be made less corrosive by an increase of the HCO content. On water treatment the following water composition should be aimed at:

• – a pH value of at least 7
• – an HCO content of at least 70 mg/l, preferably 100 mg/l
• – as low SO content as possible, or at least lower than the HCO content (both in mg/l).

     

Evaporative heat transfer characteristics of industrial safety helmets

Thermal discomfort is one of the major complaints from the wearers of industrial safety helmets. While studies have been reported on dry heat transfer (conduction, convection and radiation) in safety helmets, the investigation of wet heat dissipating (evaporation) properties has not been found in the literature. To evaluate experimentally the evaporative heat transfer characteristics of industrial safety helmets, a method was developed to simulate sweating of a human head on a thermal head manikin, and to use this manikin to assess the wet heat transfer of five industrial safety helmets. A thermal head manikin was covered with a form-fitting cotton stocking to simulate 'skin'. The skin was wetted with distilled water to simulate 'sweating'. A form-fitting perforated polyethylene film was used to cover the wetted stocking to control the skin wettedness at two levels, 0.64 and 1.0. Experiments were conducted in a climatic chamber, under the following conditions: the ambient temperature = head manikin surface temperature = 34 +/- 0.5 degrees C; ambient relative humidity 30% and 60%. Also, the effects of wind and a simulated solar heat load were investigated. The five helmets showed statistically significant difference in evaporative heat transfer under the experimental conditions. Skin wettedness, ambient humidity, wind and solar heat showed significant effects on evaporative heat transfer. These effects were different for the different helmets.     

Laser-machining experiment with an excimer laser and a kinoform

We have used a kinoform to increase the beam-power utilization in an excimer-laser-machining experiment. The kinoform creates the pattern to be machined. Thus less power is wasted on the blocking parts of a shadow mask. To achieve as smooth an intensity profile as possible, the kinoform was also used together with a microlens-array beam homogenizer. We discuss the intensity distributions of the patterns created by the kinoform with and without the beam homogenizer as well as the design of the kinoform and the homogenizer, with emphasis on the relation to the coherence properties of the laser beam.