Resident characteristics and organizational factors influencing the quality of drug use in Swedish nursing homes

Appropriateness of drug use is an important indicator of the quality of care in nursing homes. In this study, we analyzed the influence of resident characteristics and selected organizational factors on the appropriateness of psychotropic drug use in 33 Swedish nursing homes. Specific criteria based on published guidelines and recommendations were developed to measure appropriateness. Residents diagnosed with a psychiatric disorder and younger residents had more deviations from the criteria; however, resident mix did not explain variations in appropriateness of drug use at the facility level. Facilities with better nurse staffing and drug intervention teams had fewer deviations from the criteria, but only 15-20% of the variation in drug prescribing was explained by these predictors.

Dissociation of the CD4 and CXCR4 binding properties of human immunodeficiency virus type 1 gp120 by deletion of the first putative alpha-helical conserved structure

To evaluate conserved structures of the surface gp120 subunit (SU) of the human immunodeficiency virus type 1 (HIV-1) envelope in gp120-cell interactions, we designed and produced an HIV-1 IIIB (HXB2R) gp120 carrying a deletion of amino acids E61 to S85. This sequence corresponds to a highly conserved predicted amphipathic alpha-helical structure located in the gp120 C1 region. The resultant soluble mutant with a deleted alpha helix 1 (gp120 DeltaalphaHX1) exhibited a strong interaction with CXCR4, although CD4 binding was undetectable. The former interaction was specific since it inhibited the binding of the anti-CXCR4 monoclonal antibody (12G5), as well as SDF1alpha, the natural ligand of CXCR4. Additionally, the mutant gp120 was able to bind to CXCR4(+)/CD4(-) cells but not to CXCR4(-)/CD4(-) cells. Although efficiently expressed on cell surface, HIV envelope harboring the deleted gp120 DeltaalphaHX1 associated with wild-type transmembrane gp41 was unable to induce cell-to-cell fusion with HeLa CD4(+) cells. Nevertheless, the soluble gp120 DeltaalphaHX1 efficiently inhibited a single round of HIV-1 LAI infection in HeLa P4 cells, with a 50% inhibitory concentration of 100 nM. Our data demonstrate that interaction with the CXCR4 coreceptor was maintained in a SUgp120 HIV envelope lacking alphaHX1. Moreover, in the absence of CD4 binding, the interaction of gp120 DeltaalphaHX1 with CXCR4 was sufficient to inhibit HIV-1 infection.

Purification and characterization of cytosolic cytochrome P450 forms from yeasts belonging to the genus Trichosporon

The yeast Trichosporon spec. SBUG 752 isolated from soil produced cytochrome P450 during the stationary phase of growth on glucose. After cell disruption and ultracentrifugation, large amounts of P450 (250 pmol/mg protein) were found in the cytosolic fraction. In contrast, no P450 was detectable in the microsomes. Similar results were also obtained from some other yeast species of the genus Trichosporon. After purification to electrophoretic homogeneity, the P450 from Trichosporon spec. SBUG 752 migrated in SDS-PAGE with an apparent Mr of 43,000. Final purification by isoelectric focusing yielded two different isoenzymes in their spectrally active state-P450TS1 and P450TS2-having pI values of 5.9 and 6.2, respectively. Partial N-terminal amino acid sequencing revealed a high degree of sequence homology between P450TS1 and P450TS2 and their close relationship to the soluble P450 forms of the CYP55 family which are known to act as nitric oxide reductases in some filamentous fungi. The P450TS1 from Trichosporon spec. SBUG 752 catalyzed nitric oxide reduction under anaerobic conditions in an NADH- and NADPH-dependent manner-an activity not yet described for yeasts. These results demonstrate the existence of soluble P450 forms in yeasts exhibiting functional and structural characteristics similar to those of the P450 forms of the CYP55 family.

Carnitine palmitoyltransferase I (CPT I) activity and its regulation by malonyl-CoA are modulated by age and cold exposure in skeletal muscle mitochondria from newborn pigs

Whole-body lipid utilization is progressively enhanced during the first postnatal day in pigs, especially during cold exposure and muscular shivering thermogenesis. This study was designed to examine early postnatal changes in fatty acid oxidation potential, carnitine palmitoyltransferase I activity and regulation by malonyl-CoA in skeletal muscle mitochondria isolated from newborn and 5-d-old piglets. At 5 d of life, pigs were maintained for a 4-h period in thermoneutral (30 degreesC) or cold (20 degreesC) conditions. Intermyofibrillar and subsarcolemmal mitochondria were isolated from longissimus dorsi and rhomboïdeus muscles. In subsarcolemmal mitochondria, carnitine palmitoyltransferase I activity increased with age (P < 0.01) and was 80% lower (P < 0.001) than in intermyofibrillar mitochondria. Intermyofibrillar mitochondria had high enzyme activities and fatty acid oxidation potential from birth. The fatty acids 16:0, 18:1(n-9) and 18:2(n-6) were oxidized at a higher rate than 18:0 (-37%) and 8:0 (-55%). Sensitivity of carnitine palmitoyltransferase I to malonyl-CoA inhibition and malonyl-CoA levels decreased by 47% (P < 0.05) and 33% (P < 0.01) with age, respectively. After 4 h of cold exposure, sensitivity of carnitine palmitoyltransferase I to malonyl-CoA was unaffected in the rhomboideus and tended to be greater (P < 0.06) in longissimus dorsi muscle. Malonyl-CoA levels were lower (P < 0.05) in the rhomboideus and were unaffected in longissimus dorsi muscle. These results demonstrate that fatty acid oxidation is effective from birth in isolated intermyofibrillar mitochondria. The postnatal enhancement of fatty acid utilization observed in vivo can be explained, at least in part, by a rise in carnitine palmitoyltransferase I activity in subsarcolemmal mitochondria and a modulation of its activity by malonyl-CoA in intermyofibrillar mitochondria.

Faecal elastase 1: not helpful in diagnosing chronic pancreatitis associated with mild to moderate exocrine pancreatic insufficiency

BACKGROUND/AIM

The suggestion that estimation of faecal elastase 1 is a valuable new tubeless pancreatic function test was evaluated by comparing it with faecal chymotrypsin estimation in patients categorised according to grades of exocrine pancreatic insufficiency (EPI) based on the gold standard tests, the secretin-pancreozymin test (SPT) and faecal fat analysis.

METHODS

In 64 patients in whom EPI was suspected, the following tests were performed: SPT, faecal fat analysis, faecal chymotrypsin estimation, faecal elastase 1 estimation. EPI was graded according to the results of the SPT and faecal fat analysis as absent, mild, moderate, or severe. The upper limit of normal for faecal elastase 1 was taken as 200 micrograms/g, and for faecal chymotrypsin 3 U/g stool. Levels between 3 and 6 U/g stool for faecal chymotrypsin are usually considered to be suspicious for EPI. In this study, both 3 and 6 U/g stool were evaluated as the upper limit of normal.

RESULTS

Exocrine pancreatic function was normal in 34 patients, of whom 94, 91, and 79% had normal faecal elastase 1 and faecal chymotrypsin levels (< 3 U/g and < 6 U/g) respectively. Thirty patients had EPI, of whom 53, 37, and 57% had abnormal faecal enzyme levels (differences not significant). When EPI was graded as mild, moderate, or severe, 63% of patients had mild to moderate EPI, and 37% had severe EPI. In the latter group, between 73 and 91% of patients had abnormal faecal enzymes. In the group with mild to moderate EPI, abnormal test results were obtained for both faecal enzymes in less than 50% of the patients (differences not significant). Some 40% of the patients had pancreatic calcifications. There were no significant differences for either faecal enzyme between the two groups with and without pancreatic calcifications. In 62% of the patients who underwent an endoscopic retrograde cholangiopancreatography (ERCP), abnormal duct changes were found. Again, there were no significant differences for either faecal enzyme between the two groups with abnormal and normal ERCP.

CONCLUSION

Estimation of faecal elastase 1 is not distinctly superior to the traditional faecal chymotrypsin estimation. The former is particularly helpful only in detecting severe EPI, but not the mild to moderate form, which poses the more frequent and difficult clinical problem and does not correlate significantly with the severe morphological changes seen in chronic pancreatitis.

Anaerobic ammonia oxidation by cell-free extracts of Nitrosomonas eutropha

Cell-free extracts of Nitrosomonas eutropha oxidized ammonia to nitrite with NO2 (N2O4) as electron acceptor. The ammonia oxidation activity was shown to be sensitive against oxygen. In the absence of oxygen ammonia and NO2 were consumed in a ratio of approximately 1:2 and hydroxylamine occurred as an intermediate. NO was released in amounts equimolar to the consumption of NO2. After passing the cell suspension through a French pressure cell and fractionating it by density gradient centrifugation using a linear sucrose gradient, two soluble and two membrane fractions were detectable. Highest ammonia oxidation activity was measured in the membrane fractions and highest hydroxylamine oxidation activity in the soluble fractions. The KS values of the ammonia oxidizing system in cell-free extracts was about 20 microns NH3 and remained unchanged between pH 7.25 to 8.25.

[The treatment concept in severe hand injuries]

Treatment of complex injuries of the hand aims at best possible reconstruction of function and quick social and professional rehabilitation. This objective is hardly to achieve in most cases due to the severity of injury. Outcome depends on patients' age and injury pattern and essentially on the strategy of surgical treatment. Errors in prehospital emergency treatment can hardly be corrected, no matter how excellent the surgical technique may be. Traumatic multiple finger or thumb amputations are clear indications for replantation. Beginning with osteosynthesis, suture of tendons and ligaments the restoration of blood supply is the most important step. Nerve reconstruction should be performed immediately, but if tension free repair is impossible, secondary nerve grafting is preferred. Primary skin closure should be carried out if possible, in case of defects skin grafts, local or free flaps have to be used.

Leptin selectively increases energy expenditure of food-restricted lean mice

OBJECTIVE

To find out whether leptin can attenuate hypometabolic torpor-like states of metabolic rate (MR) in adult lean animals, as it attenuates the morning suppression of thermoregulatory thermogenesis in suckling-age rat pups.

DESIGN

Leptin effects on MR and food intake were studied in mice aged 4-7 months, in which a high incidence of exaggerated circadian reductions of MR had been induced by chronic food-restriction and, for comparison, in free-feeding mice.

PROTOCOL

Continuous recordings of MR, for a group of seven mice maintained at an ambient temperature of 24 degrees C, while they were repeatedly-with pauses of at least six days-treated for three consecutive days with either recombinant murine leptin (20, 200 or 600 pmol x g(-1) x d[-1]) or saline.

RESULTS

Leptin treatment caused dose-dependent 5-15% increases in energy expenditure by moderating the decreases in MR during the circadian minima, without affecting either the MR during the circadian maxima or food intake. Similar treatment of free-feeding mice caused dose-dependent decreases of food intake without changing MR.

CONCLUSION

Leptin controls thermoregulatory energy expenditure when food supplies are scarce and changes food intake, rather than energy expenditure, when food is abundant.

The impact of regular multidisciplinary team interventions on psychotropic prescribing in Swedish nursing homes

OBJECTIVE

To evaluate the impact of regular multidisciplinary team interventions on the quantity and quality of psychotropic drug prescribing in Swedish nursing homes.

DESIGN

A randomized controlled trial.

SETTING

A sample of 33 nursing homes: 15 experimental homes and 18 control homes representing 5% of all Swedish nursing homes.

PARTICIPANTS

The sample consisted of 1854 long-term care residents with an average age of 83 years. Seventy percent of the residents were women, and 42% had a documented diagnosis of dementia. An additional 5% had a psychotic disorder, and 7% had a diagnosis of depression.

INTERVENTION

Experimental homes participated in an outreach program that was designed to influence drug use through improved teamwork among physicians, pharmacists, nurses, and nurses' assistants. Multidisciplinary team meetings were held on a regular basis throughout the 12-month study period.

MEASUREMENTS

Lists of each resident's prescriptions were collected 1 month before and 1 month after the 12-month intervention. Measures included the proportion of residents with any psychotropic drug, polymedicine, and therapeutic duplication and proportion of residents with nonrecommended and acceptable drugs in each psychotropic drug class, as defined by current Swedish guidelines.

RESULTS

Baseline results show extensive psychotropic drug prescribing, with the most commonly prescribed drugs being hypnotics (40%), anxiolytics (40%), and antipsychotics (38%). After 12 months of team meetings in the experimental homes, there was a significant decrease in the prescribing of psychotics (-19%), benzodiazepine hypnotics (-37%), and antidepressants (-59%). Orders for more acceptable antidepressants also increased in the experimental homes. In the control homes there was increased use of acceptable antidepressants, but there were no significant reductions in other drug classes.

CONCLUSIONS

There is excessive prescription of psychotropic drugs in Swedish nursing homes. Improved teamwork among caregivers can improve prescribing as defined by clinical guidelines.

The leptin receptor mediates apparent autocrine regulation of leptin gene expression

The possibility that the leptin receptor (LEPR) mediates autocrine regulation of leptin expression in adipose tissue was examined in 10-day-old Zucker rat pups with different copy numbers of the leptin receptor mutation (Lepr(fa)). Plasma leptin concentrations and adipose tissue mRNA levels for leptin were related to copy number of the mutation (fa/fa > fa/+ > +/+). These relationships were independent of plasma insulin concentration. Reduced copy number for the functional leptin receptor apparently results in a diminished negative feedback signal to the leptin gene in adipose tissue. Thus, leptin appears to close a short regulatory loop controlling its own synthesis in adipose tissue.

Leptin does not reduce body fat content but augments cold defense abilities in thermoneutrally reared rat pups

A previous study showed that recombinant leptin markedly affects the body fat content and thermoregulatory energy expenditure of lean (+/+ and +/fa) suckling-age rats, and we wanted to find out whether leptin in doses that halved body fat of cold-reared lean pups had any effect in thermoneutrally reared lean pups. When +/+ pups were artificially reared from 4 to 16 days of age at thermoneutrality and treated as before with leptin from day 7, their total metabolic rate throughout the treatment period was only 4% higher than that of the control littermates and their final body fat content only 4% lower (both P>0.05). We conclude from comparisons of the results in +/+ pups at cold and thermoneutral conditions that leptin does not stimulate, but rather disinhibits, sympathetically mediated thermoregulatory thermogenesis.

Postnatal changes in mitochondrial protein mass and respiration in skeletal muscle from the newborn pig

Quantitative and functional changes occurring in mitochondria were studied in pig skeletal muscle between birth and 5 days of life. Postnatal changes were followed separately on intermyofibrillar and subsarcolemmal mitochondria isolated from rhomboïdeus (RH) and longissimus dorsi (LD) muscles. The integrity and purity of the isolated mitochondria was checked by electron microscopic observations. The mass of mitochondrial protein was not different between muscles at birth. It increased tremendously during the first 5 days of life, by 49% in LD (P < 0.001) and 93% in RH (P < 0.001) muscle and was 30% higher in RH than in LD muscle at 5 days of life (P < 0.05). Mitochondria isolated from RH muscle exhibited 30% higher oxidative and phosphorylative capacities than those from LD muscle at 5 days of life (P < 0.05). Intermyofibrillar (IM) mitochondria had high respiration rate, enzyme activities and coupling parameters (respiratory control ratio, phosphorus-oxygen ratio) from birth. Subsarcolemmal (SS) mitochondria were less active than IM mitochondria; their respiration rate and enzyme activities were 60% lower (P < 0.01) and increased with age, particularly in LD muscle (P < 0.05). Short-term cold exposure had no effect on mitochondrial mass and activity. These results suggest that muscle mitochondria are functional from birth and are changing primarily quantitatively. SS and IM mitochondria exhibit specific changes that are probably involved in the postnatal acquisition of skeletal muscle oxidative metabolism.

Positive selection and transplantation of peripheral CD34+ progenitor cells: feasibility and purging efficacy in pediatric patients with neuroblastoma

Peripheral stem cells were mobilized and collected in 20 children with stage 4 neuroblastoma. A total of 37 leukaphereses were performed in the 20 patients. The mean number of collected cells was 5.6 +/- 2.4 x 10(8)/kg (range 1.9-10.5), and the number of collected CD34+ progenitors was 6.1 +/- 6.3 x 10(6)/kg (range 0.75-21.7). CD34-positive selection was performed using the CellPro method. Of the adsorbed cells, 42 +/- 20% (range 4.3-76.6) stained positively for CD34, and the number of positively selected CD34+ cells was 2.0 +/- 1.9 x 10(6)/kg (range 0.09-7.1). The mean recovery of CD34+ cells was 36 +/- 20% (range 6-67). For detection of contaminating neuroblastoma cells before and after CD34-positive selection, a murine antidisialoganglioside GD2 antibody (14.G2a) was used, followed by the alkaline phosphatase antialkaline phosphatase (APAAP) method. Before the positive selection, various numbers of contaminating neuroblastoma cells were found in the leukaphereses of 7 patients. After positive selection, neuroblastoma cells were still detectable in all 7 patients, with a mean log depletion of tumor cells of 1.41 +/- 0.45 (range 0.69-2.13). In 1 patient, contaminating neuroblastoma cells were found only after CD34-positive selection. In 15 of the 20 patients, high-dose chemotherapy was performed, and positively selected CD34+ cells were reinfused in 12 patients. In 10 of these, the mean time to reach > 0.5 x 10(9)/L granulocytes was 12.3 +/- 1.7 days (range 10-16). One patient died at day 7 due to sepsis, and in 1 patient the backup was given at day 15. Because of the low number of collected CD34+ cells, 3 patients were grafted with a combination of unmanipulated PBSC and CD34+ progenitors. In summary, we have shown that positive selection of peripheral CD34+ progenitors is feasible in pediatric patients. However, strategies to improve the recovery of the CD34+ cells and the purging efficacy of this method (i.e., higher enrichment of CD34+ cells, combination of positive and negative selection methods) should be evaluated further.

Studies on spontaneous promoter-up mutations in the transcriptional activator-encoding gene phIR and their effects on the degradation of phenol in Escherichia coli and Pseudomonas putida

The activator-encoding gene phlR was identified upstream of the plasmid-encoded operon for phenol degradation in Pseudomonas putida strain H by cassette mutagenesis and DNA sequence analysis. The deduced amino acid sequence of PHLR shows high homology to DmpR of P. putida sp. CF600 and to the chromosomally encoded PhhR of P. putida P35X reported previously. Trans-activation of phenol degradation was observed when phlR was overexpressed in a phlR insertion mutant. Transconjugants of Escherichia coli carrying pPGH11, which contains the complete set of phl genes, are unable to grow on phenol as carbon source. However, two types of mutants were selected for further characterization that were able to metabolize phenol as sole source of carbon and energy. In both types of mutants enhanced expression of phlR is responsible for the Phl+ phenotype. In type I (pPGH13) a deletion of 1 bp made the -35 region and the spacing between the -35 and -10 regions of the phlR promoter more similar to the consensus structure. In type II (pPGH14) a duplication of the phlR 5' region was identified that includes part of the -35 motif and reduces the spacing between the -35 and -10 regions. In addition, due to the duplication of part of phlR, the distance from the phlR promoter to the catabolic phl operon is increased. Different transcriptional start sites have been identified by primer extension analysis in clones harboring pPGH14 or the wild type phlR. Quantitative primer extension analysis revealed that the greatest amount of phlR transcript is expressed from the partial, phlR duplication. Growth on phenol and phenol hydroxylase activity reflect the high level of phlR transcript in E. coli transconjugants. Overexpression of PhlR was also observed when pPGH14 was transferred into P. putida, and results in earlier induction of the phenol degradation operon relative to the wild-type strain.

Anaerobic ammonia oxidation with nitrogen dioxide by Nitrosomonas eutropha

Nitrosomonas eutropha, an obligately lithoautotrophic bacterium, was able to nitrify and denitrify simultaneously under anoxic conditions when gaseous nitrogen dioxide (NO2) was supplemented to the atmosphere. In the presence of gaseous NO2, ammonia was oxidized, nitrite and nitric oxide (NO) were formed, and hydroxylamine occurred as an intermediate. Between 40 and 60% of the produced nitrite was denitrified to dinitrogen (N2). Nitrous oxide (N2O) was shown to be an intermediate of denitrification. Under an N2 atmosphere supplemented with 25 ppm NO2 and 300 ppm CO2, the amount of cell protein increased by 0.87 mg protein per mmol ammonia oxidized, and the cell number of N. eutropha increased by 5.8 x 10(9) cells per mmol ammonia oxidized. In addition, the ATP and NADH content increased by 4.3 micromol ATP (g protein)-1 and 6.3 micromol NADH (g protein)-1 and was about the same in both anaerobically and aerobically grown cells. Without NO2, the ATP content decreased by 0.7 micromol (g protein)-1, and the NADH content decreased by 1.2 micromol (g protein)-1. NO was shown to inhibit anaerobic ammonia oxidation.

Different physiological traits underlying increased body fat of fatty (fa/fa) and heterozygous (+/fa) rats

To find out whether the most characteristic physiological traits distinguishing suckling-age fa/fa pups from lean littermates also differ between +/+ and +/fa littermates, we analyzed the body composition and cold defense of 7- and 16-day-old pups and the plasma concentrations of insulin, glucose, triglycerides, and free fatty acids in 16-day-old pups. Zucker rat x Brown Norway hybrid pups were genotyped by using a molecular marker within 0.5 cM of the fa gene. At both ages the +/fa pups had significantly more body fat than their +/+ littermates. At 7 days this difference was as large as that between +/fa and fa/fa pups, but at 16 days it was only one-seventh of the fa/fa vs. +/fa difference. In contrast, there were no heterozygote differences for three parameters that show crucial abnormalities in the fa/fa pups: thermoregulatory thermogenesis and plasma concentrations of insulin and triglycerides. The physiological mechanisms underlying the increased fat content of +/fa pups thus differ from those known to fuel most of the excessive fat deposition of their fa/fa littermates.

The aphid transmission factor of cauliflower mosaic virus forms a stable complex with microtubules in both insect and plant cells

We analyzed the distribution of the cauliflower mosaic virus (CaMV) aphid transmission factor (ATF), produced via a baculovirus recombinant, within Sf9 insect cells. Immunogold labeling revealed that the ATF colocalizes with an atypical cytoskeletal network. Detailed observation by electron microscopy demonstrated that this network was composed of microtubules decorated with paracrystalline formations, characteristic of the CaMV ATF. A derivative mutant of the ATF, unable to self-assemble into paracrystals, was also analyzed. This mutant formed a net-like structure, with a mesh of four nanometers, tightly sheathing microtubules. Both the ATF- and the derivative mutant-microtubule complexes were highly stable. They resisted dilution-, cold-, and calcium-induced microtubule disassembly as well as a combination of all three for over 6 hr. CaMV ATF cosedimented with microtubules and, surprisingly, it bound to Taxol-stabilized microtubules at high ionic strength, thus suggesting an atypical interaction when compared with that usually described for microtubule-binding proteins. Using immunofluorescence double labeling we also demonstrated that the CaMV ATF colocalizes with the microtubule network when expressed in plant cells.

Leptin reduces juvenile fat stores by altering the circadian cycle of energy expenditure

The recently identified hormone leptin (ob protein) secreted by white adipose tissue is widely thought to provide a feedback signal limiting fat storage by decreasing food intake. By artificially rearing leptin-treated and control littermates fed identical amounts of milk, however, we show here that lean suckling-age rats treated with recombinant murine leptin can reduce fat storage solely by increasing energy expenditure. Continuous measurements of core temperature and metabolic rate show that this increase is not uniform throughout the day but is especially prominent in the morning when rat pups usually conserve energy by entering a torpor-like state. Leptin's alleviation of hypometabolic, torpor-like states is thus not restricted to cases of impaired hormone production but seems instead to be a normal biological function independent of its effects on food intake.

Manipulation of potential perinatal zeitgebers for the juvenile circadian temperature rhythm in rats

We investigated the importance of pre- and postnatal maternal rhythmicity for the development and synchronization of the juvenile circadian core temperature (Tc) rhythm in rats by evaluating the Tc of artificially reared pups in six litters derived from mothers maintained in continuous bright light (LL) and impregnated after drinking behavior stopped showing circadian periodicity. Pups removed from their aperiodic mothers on postnatal day 9 and artificially reared for 3 days showed a free-running Tc rhythm whose amplitude (3.1 +/- 0.1 degrees C, n = 47) was only slightly smaller than that of control pups born to mothers maintained in a 12:12-h light-dark cycle. In four litters the acrophases were not much less synchronized than in the four control litters (mean vector lengths 0.79 +/- 0.05 vs. 0.94 +/- 0.04). In two litters synchronization among littermates was not significant. Additional experiments with cross-fostered pups showed that synchronization is not caused by the time of birth. We conclude that synchronization among littermates can develop even when maternal rhythmicity has been suppressed even before conception, possibly because the Tc decrease of several littermates happening to have similar phases at birth acts as zeitgeber.

Dimeric lipoprotein lipase is bound to triglyceride-rich plasma lipoproteins

Lipoprotein lipase hydrolyzes the triglyceride-rich core of chylomicrons and very low density lipoproteins. It is also a ligand, in vitro, for binding of lipoproteins to the low density lipoprotein receptor-related protein and may play a central role in the receptor-mediated removal of triglyceride-rich lipoproteins. The aim of the present study was to determine to which lipoprotein subclass the enzyme is bound in preheparin plasma and when released into plasma by heparin injection. Tetrahydrolipstatin, a potent inhibitor of serine lipases, was used to block lipolytic activity, thereby preventing changes in plasma lipoproteins due to ex vivo lipolysis. To analyze the distribution pattern of lipoprotein lipase dimers among lipoprotein classes, a specific ELISA was used and gel filtration was performed in pre- and postheparin plasma from five subjects with triglyceride ranging from 69 to 522 mg/dl. When lipolytic activity was not inhibited, lipoprotein lipase dimers eluted in association with low and high density lipoproteins, reproducing results previously obtained by several groups of investigators. However, in pre- and postheparin samples treated with tetrahydrolipstatin, most of the dimeric enzyme was found associated with very low density lipoprotein particles. In conclusion in pre- and postheparin samples most of the lipoprotein lipase dimers are associated with very low density lipoproteins when ex vivo lipolytic activity is inhibited, which supports the hypothesis that, in vivo, lipoprotein lipase may affect the receptor-mediated removal of these particles. Moreover, it suggests that the association between lipoprotein lipase and cholesterol-rich lipoproteins might be an ex vivo phenomenon due to lack of inhibition of lipolytic activity.

Improved traceability of pH measurements

Traceability is a prerequisite for the comparability and uniformity of measurements. Although pH-measurements are carried out on a large scale in laboratory and industry, the problems involved in the traceability of pH values have not adequately been solved in the past. The comparability of pH measurements is limited, among other parameters, by the accuracy of the pH values of the standard buffer solutions used to calibrate the pH meter-electrode assemblies. The measured pH(X) value must be traceable to primary standard pH(PS) values through an unbroken chain of comparisons, all values having stated uncertainties. A new primary standard measurement device for pH is used to certify primary pH reference materials from which these secondary reference materials can be derived.

Is the onset of obesity in suckling fa/fa rats linked to a potentially larger milk intake?

We wanted to find out whether fatty (fa/fa) sucklings show abnormal intake when given access to an abundant milk reservoir. To do this, we gravimetrically determined the milk ingested by small groups (4-5 pups) of 5- to 15-day-old lean (+/fa) and fatty littermates allowed to suckle for 30 min after their mother had not been nursing for periods of between 1 and 7 h. The pups were grouped randomly and their phenotypes retrospectively identified. Within both genotypes, the intakes of simultaneously tested pups were significantly higher in pups deprived for longer periods. Deprived and undeprived fa/fa pups ingested, however, slightly but significantly less milk than +/fa littermates did in the same nursing bout. In the first 2 wk of life, when fa/fa pups deposit nearly twice as much body fat as their +/fa littermates do, fa/fa pups will thus suckle less rather than more milk. This extends previous findings showing that the onset of fa/fa obesity is independent of larger intakes and thus questions that fa impairs a receptor primarily controlling food intake.

Apoptotic cell death in activated monocytes following incorporation of clodronate-liposomes

The present study was performed to elucidate whether sterically stabilized liposomes laden with clodronate, which lead to depletion of macrophages (Mphis) and amelioration of experimental autoimmune arthritis in vivo, selectively affect cells of the mphi lineage in vitro. The rates of incorporation of drug-free, fluorescent liposomes and the rates of cell death following exposure to clodronate-liposomes were assessed in human peripheral blood monocytes, as well as in polymorphonuclear leukocytes (PMNs), T cells, endothelial cells, and fibroblasts, both at rest and following activation. Gel electrophoresis of nuclear extracts and ultrastructural analyses were performed to identify the modality of cell death. Monocytes, particularly upon activation, were more efficient in incorporating sterically stabilized liposomes than all other cells except PMNs. Twenty percent of resting monocytes and up to 65% of activated monocytes died within 24 h of exposure to clodronate-liposomes, whereas the other cell types, including PMNs, remained unaffected. Activated monocytes exposed to clodronate-liposomes, but not resting or activated monocytes exposed to drug-free liposomes, showed clear signs of apoptotic cell death. In most of the assays, sterically stabilized liposomes were more efficient than conventional phosphatidylcholine-liposomes. Sterically stabilized clodronate-liposomes preferentially affect cells of the mphi lineage, particularly if activated. Selective elimination of activated Mphis by apoptosis may explain both therapeutic efficacy and safety of clodronate-liposomes in experimental models of autoimmunity.