Adaptive timing of digestion and digestion-related thermogenesis in the pigeon

Pigeons were allowed to feed for 1 h either 2 h after lights on (morning pulse) or 3 h before lights off (evening pulse). Body temperature was measured radiotelemetrically. Faecal excretion, as an index of rate of digestion, was measured using load cells. At 22 degrees C, faecal excretion peaked just after lights-on in morning-pulse condition, but not in evening-pulse condition. In the cold (+5 degrees C), the peak was absent. We conclude that at thermoneutrality, pigeons are able to postpone a major part of digestion until late in the dark phase when their body temperature is increasing to the diurnal level. Thus, the extra heat from digestion-related thermogenesis that otherwise would be dissipated into the environment can be used for rewarming. In the cold, such a delay is not necessarily advantageous as the extra heat can always be used to substitute for thermoregulatory thermogenesis. The occurrence of concentrated period of digestion only in the morning-pulse condition was correlated to a lower food intake and lower body temperature as compared with the evening-pulse condition. Restricted feeding may thus be needed to induce adaptive timing of digestion as a mechanism of energy sparing. In addition to storage of food, timing of digestion may be a significant factor in the evolution of the crop in birds.     

Production of Chlamydia pneumoniae proteins in Bacillus subtilis and their use in characterizing immune responses in the experimental infection model

Due to intracellular growth requirements, large-scale cultures of chlamydiae and purification of its proteins are difficult and laborious. To overcome these problems we produced chlamydial proteins in a heterologous host, Bacillus subtilis, a gram-positive nonpathogenic bacterium. The genes of Chlamydia pneumoniae major outer membrane protein (MOMP), the cysteine-rich outer membrane protein (Omp2), and the heat shock protein (Hsp60) were amplified by PCR, and the PCR products were cloned into expression vectors containing a promoter, a ribosome binding site, and a truncated signal sequence of the alpha-amylase gene from Bacillus amyloliquefaciens. C. pneumoniae genes were readily expressed in B. subtilis under the control of the alpha-amylase promoter. The recombinant proteins MOMP and Hsp60 were purified from the bacterial lysate with the aid of the carboxy-terminal histidine hexamer tag by affinity chromatography. The Omp2 was separated as an insoluble fraction after 8 M urea treatment. The purified proteins were successfully used as immunogens and as antigens in serological assays and in a lymphoproliferation test. The Omp2 and Hsp60 antigens were readily recognized by the antibodies appearing after pulmonary infection following intranasal inoculation of C. pneumoniae in mice. Also, splenocytes collected from mice immunized with MOMP or Hsp60 proteins proliferated in response to in vitro stimulation with the corresponding proteins.     

Dynamic changes during the immune response in T cell-antigen-presenting cell clusters isolated from lymph nodes

Activation of antigen-specific T cells by mature dendritic cells in secondary lymphoid organs is a key control point of the adaptive immune response. Here we describe the ex vivo isolation of preformed multicellular clusters between T cells and antigen-presenting cells. Adoptively transferred, antigen-specific T cells segregated into individual clusters where their activation and proliferation was initiated in vivo. Transit of the T cell cohort through the cluster compartment required 32-36 h. The precise timing of the response to agonistic epitopes was remarkably invariant regardless of the T cell lineage, the major histocompatibility complex haplotype, and the antigen dose. Interestingly, initiation of cell division of T cells specific for a subdominant epitope and a weak agonist was delayed by 6 h. The results provide a basis for the analysis of short range, mutual cell-cell interactions within such confined microenvironments.     

Maxillary expansion in Class II correction with orthopedic cervical headgear. A posteroanterior cephalometric study

Class-II, division-1 malocclusion appears to be associated with a narrow maxilla. A Class-II malocclusion may be corrected to a Class-I relationship in children using a cervical headgear provided that the narrow maxilla is expanded. This expansion is possible using headgear by dental cast analysis, but this has not been confirmed by cephalometry. We studied the effects of orthopedic cervical headgear on dental and skeletal facial widths in 40 children aged 9.1 (7.2-11.5) who had Class-II, division-I malocclusions. The headgear consisted of a long outer bow bent 15 degrees upward and a large inner bow expanded by 10 mm. Posteroanterior cephalographs and dental casts were taken before and after treatment. The results were compared with the control values presented in the literature. The malocclusion was treated to a Class-I relationship in all children. The average treatment time was 1.6 (0.3-3.1) years. The maxilla was widened significantly (P < .0001). The upper first molar width (um-um) and maxillary width (mx-mx) increased 3.2 and 1.6 mm/y, respectively. Maxillary widening was also observed in the nasal structure as indicated by an increase in lateronasal width (lap-lap) by 1.0 mm/y (P < .005). With maxillary widening, the mandibular dental arch widened spontaneously. The lower first molar width (lm-lm) increased 0.8 mm/y, which was more than the increase in the controls (P < .0001). However, the antegonial width (ag-ag) remained unaffected. By using a widened inner bow in headgear therapy with Class-II malocclusions, a widening of maxilla and nasal cavity may be obtained.     

Effects of identical weight loss on body composition and features of insulin resistance in obese women with high and low liver fat content

Our objective was to determine how 8% weight loss influences subcutaneous, intra-abdominal, and liver fat (LFAT), as well as features of insulin resistance, in obese women with high versus low LFAT. A total of 23 women with previous gestational diabetes were divided into groups of high (9.4 +/- 1.4%) and low (3.3 +/- 0.4%) LFAT based on their median LFAT (5%) measured with proton spectroscopy. Both groups were similar with respect to age, BMI, and intra-abdominal and subcutaneous fat. Before weight loss, women with high LFAT had higher fasting serum insulin and triglyceride concentrations than women with low LFAT. At baseline, LFAT correlated with the percent of fat (r = 0.44, P < 0.05) and saturated fat (r = 0.45, P < 0.05) of total caloric intake but not intra-abdominal or subcutaneous fat or fasting serum free fatty acids. Weight loss was similar between the groups (high LFAT -7.4 +/- 0.2 vs. low LFAT -7.7 +/- 0.3 kg). LFAT decreased from 9.4 +/- 1.4 to 4.8 +/- 0.7% (P < 0.001) in women with high LFAT and from 3.3 +/- 0.4 to 2.0 +/- 0.2% (P < 0.001) in women with low LFAT. The absolute decrease in LFAT was significantly higher in women with high than low LFAT (-4.6 +/- 1.0 vs. -1.3 +/- 0.3%, P < 0.005). The decrease in LFAT was closely correlated with baseline LFAT (r = -0.85, P < 0.001) but not with changes in the volumes of intra-abdominal or subcutaneous fat depots, which decreased similarly in both groups. LFAT appears to be related to the amount of fat in the diet rather than the size of endogenous fat depots in obese women. Women with initially high LFAT lost more LFAT by similar weight loss than those with low LFAT, although both groups lost similar amounts of subcutaneous and intra-abdominal fat. These data suggest that LFAT is regulated by factors other than intra-abdominal and subcutaneous fat. Therefore, LFAT does not appear to simply reflect the size of endogenous fat stores.     

Influence of the aqueous film coating process on the properties and stability of tablets containing a moisture-labile drug

The effects of an aqueous film coating process on the morphology and storage stability of hydroxypropyl methylcellulose-coated tablets containing a moisture-labile model drug (acetylsalicylic acid, ASA) were evaluated using an instrumented side-vented tablet pan coater. Coating parameters studied were inlet air absolute humidity 5 g/m3 and 12 g/m3, spraying air pressure 100 kPa and 500 kPa, pan air temperature 35 degrees C and 55 degrees C, and coating solution flow rate 2.2 g/min and 7.8 g/min. The surface roughness of the coatings was measured with a laser profilometer and the chemical hydrolysis of the model drug ASA with an UV-spectrophotometer. The film-coated tablets were stored at 25 degrees C/60% RH and 40 degrees C/75% RH for three months. The high absolute humidity of the inlet air increased the residual water content and surface roughness of the coated tablets. Using a lower coating solution flow rate, higher spraying air pressure and pan temperature the coatings were smooth and homogeneous. In both ambient and accelerated storage conditions, the roughness of the coatings and the hydrolysis of ASA increased, but this was independent of the film coating process. Uniform and smooth hydroxypropyl methylcellulose coatings can be achieved by improved control of process parameters related to the application of the coating solution and water evaporation of the tablet surface.     

Doxorubicin induces apoptosis in germ line stem cells in the immature rat testis and amifostine cannot protect against this cytotoxicity

The underlying primary damage to the seminiferous epithelium caused by chemotherapeutic regimens at childhood is largely unknown. The present investigation was designed to identify acute cytotoxic events in the testis caused by a single dose of doxorubicin. Male rats at 6, 16, and 24 days of age were injected with doxorubicin (3 mg/kg, i.p.) or vehicle (saline) alone and 24 and 48 hours later, the germ cell types and apoptotic cells in the seminiferous epithelium were examined.As indicated by microscopy and terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling staining, an 8-fold increase in the number of apoptotic germ cells in the testes of 6-day-old rats was observed 48 hours after doxorubicin treatment. Spermatogonia migrating to the basement membrane were the primary cell type undergoing this induced apoptosis. A single dose of amifostine (200 mg/kg) administered i.p. 15 minutes before injection of doxorubicin provided no protection against this enhanced apoptosis. Under the same conditions, testicular levels of p53 and activated caspase 8 were elevated, whereas the level of murine double minute-2 was lowered. In contrast, doxorubicin treatment did not result in any significant change in the physiologic, stage-specific germ cell apoptosis occurring in the testes of 16- and 24-day-old rats. These observations suggest that the initiation phase of spermatogenesis is highly sensitive to doxorubicin-induced apoptosis. Gonocytes and early spermatogonia are the cell types that are vulnerable to this p53-trigged apoptosis, which results in a decrease in the size of the pool of germ-line stem cells. Amifostine fails to protect the germ cells against this cytotoxic insult.     

Valinomycin-induced apoptosis of human NK cells is predominantly caspase independent

Human NK cells are sensitive to the exogenous toxic compound valinomycin. This toxin, produced by Streptomyces griseus in moisture damaged buildings, induces apoptosis by dissipating the membrane potential in mitochondria. In this paper, we show that valinomycin-induced apoptosis involves two different pathways in human NK cells: the predominant one is caspase-3 independent and the other caspase-3 dependent. Resting human NK cells were found to contain high amounts of active caspase-3 as compared to the T cells in which high caspase-3 activity has been shown only after stimulation. Exposure to valinomycin did not alter the caspase-3 activity of human NK cells but induced nucleosomal fragmentation of DNA. General caspase inhibitor, Z-VAD-FMK, inhibited completely the caspase-3 activity, reduced DNA cleavage but did not prevent the spontaneous or valinomycin-induced apoptosis of NK cells. The endogenous high caspase-3 had only a slight effect on the major functions of human NK cells, i.e. cytotoxicity or gamma-IFN production, giving us a reason to suspect that the biological role of caspase-3 in NK cells could be the elimination of potentially harmful NK clones through apoptosis.     

Self-reported occupational health hazards and measured exposures to airborne impurities and noise in shoe repair work

The authors identified occupational risk factors of shoe repairers and measured their exposures to organic solvents, dust, chromium, degradation products of synthetic shoe materials, and noise. Exposures were measured in 11 shops selected from the workplaces of 82 repairers who responded to a questionnaire about their work environments. The questions dealt with, e.g., chemicals used, work related diseases, perceived hazards in the environment, ventilation, and use of personal protective equipment. Solvent vapor concentration averaged 1.95 (range 0.01-13.2) times the occupational limit (OL) of the mixture during gluing, with higher levels in facilities with no mechanical ventilation. TWA concentrations of organic solvents averaged 0.34 (range 0.01-1.23) times OLs in the breathing-zone samples. Of all shoe repair shops in Finland, 30% had no mechanical ventilation. Concentrations of airborne particles were 0.07-1.01 mg/m3, and those of insoluble and hexavalent chromium 0.10-0.32 and 0.01-0.08 microg/m3, respectively, near roughing, scoring and finishing machines. Several polymer degradation products were present in the air during machining of shoes. Ventilation exchange rates in shops with natural ventilation were less than once/hour. The repairers' average exposure to noise was below 85 dB. They reported many work-related diseases such as rhinitis (prevalence 21%), musculoskeletal disorders (16%), and dermatitis (9%). Measured dust concentrations were low, but the shoe repairers considered dust to be the most common hazard.     

In vitro toxicity of cereulide on porcine pancreatic Langerhans islets

Cereulide is a K⁺ ionophore cytotoxic and mitochondriotoxic to primary cells and cell lines of human and other mammalian origins. It is a heat-stable, highly lipophilic (log K_ow 5.96) peptide (1152 g mol⁻¹) produced by certain strains of Bacillus cereus, a bacterium connected to emetic food poisonings. In this study the pancreatic toxicity of purified cereulide, and cereulide-containing bacterial extracts, was studied using fetal porcine Langerhans islets in culture. Exposure to 1 ng ml⁻¹ of purified cereulide caused necrotic cell death of the islet cells impairing their insulin content within 2 days. Cell extracts of cereulide-positive B. cereus strains connected to food poisoning or isolated from foodstuffs were toxic, corresponding to their measured cereulide content. Extracts of B. cereus strains producing or not producing the B. cereus diarrheal toxin, but no cereulide, were tolerated by the porcine islet cultures up to concentrations 1000-fold higher compared to extracts from strains containing cereulide, and up to exposure times of 7 d. Cereulide thus was identified as the B. cereus-produced substance toxic towards porcine fetal Langerhans islets and beta cells.