Showing papers by "Uppsala University published in 1995"

A Theoretical Basis for a Biopharmaceutic Drug Classification: The Correlation of in Vitro Drug Product Dissolution and in Vivo Bioavailability

Abstract: A biopharmaceutics drug classification scheme for correlating in vitro drug product dissolution and in vivo bioavailability is proposed based on recognizing that drug dissolution and gastrointestinal permeability are the fundamental parameters controlling rate and extent of drug absorption. This analysis uses a transport model and human permeability results for estimating in vivo drug absorption to illustrate the primary importance of solubility and permeability on drug absorption. The fundamental parameters which define oral drug absorption in humans resulting from this analysis are discussed and used as a basis for this classification scheme. These Biopharmaceutic Drug Classes are defined as: Case 1. High solubility-high permeability drugs, Case 2. Low solubility-high permeability drugs, Case 3. High solubility-low permeability drugs, and Case 4. Low solubility-low permeability drugs. Based on this classification scheme, suggestions are made for setting standards for in vitro drug dissolution testing methodology which will correlate with the in vivo process. This methodology must be based on the physiological and physical chemical properties controlling drug absorption. This analysis points out conditions under which no in vitro-in vivo correlation may be expected e.g. rapidly dissolving low permeability drugs. Furthermore, it is suggested for example that for very rapidly dissolving high solubility drugs, e.g. 85% dissolution in less than 15 minutes, a simple one point dissolution test, is all that may be needed to insure bioavailability. For slowly dissolving drugs a dissolution profile is required with multiple time points in systems which would include low pH, physiological pH, and surfactants and the in vitro conditions should mimic the in vivo processes. This classification scheme provides a basis for establishing in vitro-in vivo correlations and for estimating the absorption of drugs based on the fundamental dissolution and permeability properties of physiologic importance.

Spatial disease clusters: detection and inference.

Abstract: We present a new method of detection and inference for spatial clusters of a disease. To avoid ad hoc procedures to test for clustering, we have a clearly defined alternative hypothesis and our test statistic is based on the likelihood ratio. The proposed test can detect clusters of any size, located anywhere in the study region. It is not restricted to clusters that conform to predefined administrative or political borders. The test can be used for spatially aggregated data as well as when exact geographic co-ordinates are known for each individual. We illustrate the method on a data set describing the occurrence of leukaemia in Upstate New York.

Crystallographic and molecular-modeling studies of lipase B from Candida antarctica reveal a stereospecificity pocket for secondary alcohols.

Abstract: Many lipases are potent catalysts of stereoselective reactions and are therefore of interest for use in chemical synthesis. The crystal structures of lipases show a large variation in the shapes of their active site environments that may explain the large variation in substrate specificity of these enzymes. We have determined the three-dimensional structure of Candida antarctica lipase B (CALB) cocrystallized with the detergent Tween 80. In another crystal form, the structure of the enzyme in complex with a covalently bound phosphonate inhibitor has been determined. In both structures, the active site is exposed to the external solvent. The potential lid-forming helix alpha 5 in CALB is well-ordered in the Tween 80 structure and disordered in the inhibitor complex. The tetrahedral intermediates of two chiral substrates have been modeled on the basis of available structural and biochemical information. The results of this study provide a structural explanation for the high stereoselectivity of CALB toward many secondary alcohols.

Complete sequencing of the p53 gene provides prognostic information in breast cancer patients, particularly in relation to adjuvant systemic therapy and radiotherapy

Abstract: The complete coding region of the p53 gene was sequenced from 316 consecutively presented breast cancers, of which 97 were lymph node positive and 206 were node negative. The p53 status was related to prognosis and effect of adjuvant therapy. In all, 69 individual mutations, 29 in node-positive tumours, were demonstrated throughout the whole coding sequence. The mutation sites were partly different for node-positive and node-negative patients. p53 mutations in the evolutionary conserved regions II and V were associated with significantly worse prognosis. Adjuvant systemic therapy, especially with tamoxifen, along with radiotherapy seemed to be of less value to p53 mutation- and lymph node-positive tumours.

Gratuitous overexpression of genes in Escherichia coli leads to growth inhibition and ribosome destruction.

Abstract: We attempted to test the idea that the relative abundance of each individual tRNA isoacceptor in Escherichia coli can be altered by varying its cognate codon concentration. In order to change the overall codon composition of the messenger pool, we have expressed in E. coli lacZ with the aid of T7 RNA polymerase so that their respective gene products individually accounted for 30% of the total bacterial protein. Unexpectedly, the maximum expression of either test gene has no specific effect on the relative rates of synthesis of the tRNA species that we studied. Instead, we find that there is a cumulative breakdown of rRNAs, which results in a loss of ribosomes and protein synthetic capacity. After either of the test genes is maximally induced, there is a growing fraction of protein synthesis invested in beta-galactosidase or delta tufB that is matched by a comparable decrease of the fraction of normal protein synthesis. We have also observed enhanced accumulation of two heat shock proteins during overexpression. Finally, after several hours of overexpression of either test protein, the bacteria are no longer viable. These results are relevant to the practical problems of obtaining high expression levels for cloned proteins.

Self-aggregation and phase behavior of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymers in aqueous solution

Abstract: The phase behavior and aggregation properties of block copolymers of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (Pluronics, poloxamers) in aqueous solution have recently attracted much attention. Both experimental and theoretical studies are reviewed, not comprehensively, but with the focus on studies, partly cooperative, partly independent, performed by groups in Uppsala (light scattering and fluorescence), Roskilde (rheology and calorimetry), Riso (SANS), Graz (x-ray and speed of sound), and Lund (theoretical model calculations).

Restored insulin sensitivity but persistently increased early insulin secretion after weight loss in obese women with polycystic ovary syndrome.

Abstract: The impact of weight reduction on metabolic, endocrine, and anthropometric variables was studied in 13 obese, insulin-resistant women with the polycystic ovary syndrome (PCOS). Insulin sensitivity (euglycemic insulin clamp), insulin secretion and glucose tolerance (iv glucose tolerance test), basal sex steroid hormones, gonadotropins and free fatty acids (FFA), skin folds and waist hip ratio (WHR) were evaluated before (PCO-BD) and after (PCO-AD) diet-induced weight reduction to a weight stable level [mean (SD) diet duration 14.9 (6.2) months]. Mean weight loss was 12.4 kg (4.7; P < 0.0001), equalling a reduction from a body mass index (BMI) of 32.2 (3.7) kg/m2 to 27.6 (3.7; P < 0.0001) kg/m2. The results were compared with those of two groups of weight stable (no diet) women, 21 with PCOS (PCO-ND) and 23 normal control subjects (C), who were matched to the BMI the diet group reached after weight loss. Insulin sensitivity index (M/I) improved on average 132% (P < 0.001) and plasma FFA by 32% (P < 0.01), serum sex hormone binding globulin levels increased by 35% (P < 0.01), and the sum of truncal-abdominal skin-folds (subscapular, umbilical, and suprailiacal) were reduced by 28% (P < 0.0001), whereas the early insulin response to iv glucose, the levels of gonadotropins and androstenedione, and the femoral sc fat did not change significantly with weight loss. M/I, levels of SHBG and FFA and truncal-abdominal fat reached levels similar to the controls, whereas PCO-ND had lower M/I (P < 0.01) and SHBG levels (P < 0.0001), greater concentrations of FFA (P < 0.01) and truncal-abdominal fat (P < 0.05) than C. Among women with normal glucose tolerance, the insulin increment was higher in both PCO-AD (P < 0.05) and PCO-ND (P < 0.01) than in C. There was a strong correlation between M/I and sum of truncal-abdominal skinfolds in all groups (PCO-BD: r = 0.82; P < 0.001, PCO-AD: r = 0.68; P < 0.05, PCO-ND: r = 0.81; P < 0.0001, C: r = 0.44; P < 0.05). The variation in M/I in PCO-AD and PCO-ND (pooled) was best explained by FFA and truncal-adbominal fat (model R2 = 0.67). In conclusion, insulin resistance in obese women with PCOS was reduced by weight loss to similar levels as BMI-matched control subjects, suggesting that insulin resistance in PCOS is not a feature of PCOS per se.(ABSTRACT TRUNCATED AT 400 WORDS)

Integrability and Seiberg-Witten Exact Solution

Abstract: The exact Seiberg-Witten (SW) description of the light sector in the $N=2$ SUSY $4d$ Yang-Mills theory is reformulated in terms of integrable systems and appears to be a Gurevich-Pitaevsky (GP) solution to the elliptic Whitham equations. We consider this as an implication that dynamical mechanism behind the SW solution is related to integrable systems on the moduli space of instantons. We emphasize the role of the Whitham theory as a possible substitute of the renormalization-group approach to the construction of low-energy effective actions.

Lung Cancer in Radon-Exposed Miners and Estimation of Risk From Indoor Exposure

Abstract: Background : Radioactive radon is an inert gas that can migrate from soils and rocks and accumulate in enclosed areas, such as homes and underground mines. Studies of miners show that exposure to radon decay products causes lung cancer. Consequently, it is of public health interest to estimate accurately the consequences of daily, low-level exposure in homes to this known carcinogen. Epidemiologic studies of residential radon exposure are burdened by an inability to estimate exposure accurately, low total exposure, and subsequent small excess risks. As a result, the studies have been inconclusive to date. Estimates of the hazard posed by residential radon have been based on analyses of data on miners, with recent estimates based on a pooling of four occupational cohort studies of miners, including 360 lung cancer deaths. Purpose : To more fully describe the lung cancer risk in radon-exposed miners, we pooled original data from 11 studies of radon-exposed underground miners, conducted a comprehensive analysis, and developed models for estimating radon-associated lung cancer risk. Methods : We pooled original data from 11 cohort studies of radon-exposed underground miners, including 65 000 men and more than 2700 lung cancer deaths, and fit various relative risk (RR) regression models. Results : The RR relationship for cumulative radon progeny exposure was consistently linear in the range of miner exposures, suggesting that exposures at lower levels, such as in homes, would carry some risk. The exposure-response trend for never-smokers was threefold the trend for smokers, indicating a greater RR for exposure in never-smokers. The RR from exposure diminished with time since the exposure occurred. For equal total exposure, exposures of long duration (and low rate) were more harmful than exposures of short duration (and high rate). Conclusions: In the miners, about 40% of all lung cancer deaths may be due to radon progeny exposure, 70% of lung cancer deaths in never-smokers, and 39% of lung cancer deaths in smokers. In the United States, 10% of all lung cancer deaths might be due to indoor radon exposure, 11% of lung cancer deaths in smokers, and 30% of lung cancer deaths in never-smokers. This risk model estimates that reducing radon in all homes exceeding the U. S. Environmental Protection Agency's recommended action level may reduce lung cancer deaths about 2%-4%. These estimates should be interpreted with caution, because concomitant exposures of miners to agents such as arsenic or diesel exhaust may modify the radon effect and, when considered together with other differences between homes and mines, might reduce the generalizability of findings in miners. [J Natl Cancer Inst 87 :817-827, 1995]

Trade-offs between life-history traits and a secondary sexual character in male collared flycatchers

Abstract: IT has often been suggested that sexual selection may have important consequences for life-history evolution and vice versa1-5. We manipulated the parental effort of male collared flycatchers (Ficedula albicollis) by changing the number of offspring in their nests and found a trade-off between parental effort and the size of the male's forehead patch (a secondary sexual character) in the following year. We report here that, in addition to this intra-generational trade-off, we found an inter-generational trade-off: the size of the forehead patch in first-year males was negatively related to the change in brood size of the nest in which they were raised. This has consequences for reproductive success because males with large patches mate with more females and have higher lifetime reproductive success. To our knowledge, this is the first experimental demonstration that life-history traits and secondary sexual characters trade off against each other. Our results support the suggestion that the life-history consequences of sexual ornaments are important in their evolution2-4.

Bladder and Kidney Cancer Following Cyclophosphamide Therapy for Non-Hodgkin's Lymphoma

Abstract: BACKGROUND: Cyclophosphamide is an established bladder carcinogen, but few studies have examined the relationship between dose and effect. The largest analysis to date included only seven cases of bladder cancer. No investigation has estimated the risk of kidney cancer. PURPOSE: The purpose of this study was to quantify the risk of bladder and kidney cancer following cyclophosphamide therapy. METHODS: Within a cohort of 6171 two-year survivors of non-Hodgkin's lymphoma (NHL), 48 patients with secondary cancer of the urinary tract were identified and matched to 136 control subjects with NHL who did not develop a second malignancy. Detailed information on chemotherapeutic drugs and cumulative dose received was collected for all subjects. Radiation dose to the target organ was estimated from individual radiotherapy records. Evaluations of the risk of second cancer as a result of treatment with cyclophosphamide alone, radiation alone, or both therapies were made relative to those patients who were exposed to neither treatment modality. RESULTS: A significant 4.5-fold risk of bladder cancer (95% confidence interval [CI] = 1.5-13.6) followed therapy with cyclophosphamide, and risk was dependent upon cumulative dose. Among patients who received a total amount of cyclophosphamide of less than 20 g, a nonsignificant 2.4-fold risk of bladder cancer was apparent. Significantly elevated sixfold (95% CI = 1.3-29) and 14.5-fold (95% CI = 2.3-94) risks of bladder malignancy followed cumulative doses of 20-49 g and 50 g or more, respectively (P value for trend = .004). Radiotherapy given without cyclophosphamide was associated with a nonsignificant increased risk of bladder malignancy. Excess bladder cancer risk following treatment with both radiotherapy and cyclophosphamide was as expected if individual risks were summed. Neither radiotherapy nor cyclophosphamide was associated with excesses of kidney cancer. CONCLUSIONS: Cyclophosphamide-related bladder cancer is dose dependent. For patients given cumulative doses between 20 and 49 g, the absolute risk of bladder cancer is on the order of three excess cancers per 100 NHL patients after 15 years of follow-up. At cumulative doses of 50 g or more, the excess risk increases to approximately seven excess bladder cancers per 100 NHL patients. IMPLICATIONS: The strong dose-response relationship and high absolute risk of bladder cancer underscore the importance of limiting the cumulative dose of cyclophosphamide to what is required to achieve therapeutic end points. The risk of secondary bladder malignancy and other late sequelae of therapy must be carefully weighted against the curative gains provided by cyclophosphamide. Moreover, long-term side effects of therapy that might be acceptable in cancer treatment may need to be re-evaluated for patients with non-neoplastic disorders.

Functions of hyaluronan.

Abstract: In the middle of the last century, synovial fluid had already been reported to contain a 'mucin' which gave the fluid its viscosity and lubricating properties.' In 1939, Meyer et al2 identified the viscous component of this mucin as hyaluronan (hyaluronic acid), a polysaccharide previously isolated from the bovine vitreous body.3 Subsequent work focused largely on determining the concentration of hyaluronan in, and the viscosity of, pathological synovial fluids' 4-6 compared with normal fluids. At the same time, other research groups began a physicochemical characterisation of synovial hyaluronan.7 8 Ever since this pioneering work, the role of hyaluronan in the joint under normal and pathological conditions has continued to arouse interest, especially so after the introduction of intra-articular injections of hyaluronan in the treatment of joint disorders.9 We have acquired a large amount of knowledge on hyaluronan since the thirties, but do we today know more about its real function in the joints? The structure, physical chemical properties and biology of hyaluronan have been frequently reviewed and the reader is referred to these articles.'0-'3

Analysis of cell size and DNA content in exponentially growing and stationary-phase batch cultures of Escherichia coli.

Abstract: Escherichia coli strains were grown in batch cultures in different media, and cell size and DNA content were analyzed by flow cytometry. Steady-state growth required large dilutions and incubation for many generations at low cell concentrations. In rich media, both cell size and DNA content started to decrease at low cell concentrations, long before the cultures left the exponential growth phase. Stationary-phase cultures contained cells with several chromosomes, even after many days, and stationary-phase populations exclusively composed of cells with a single chromosome were never observed, regardless of growth medium. The cells usually contained only one nucleoid, as visualized by phase and fluorescence microscopy. The results have implications for the use of batch cultures to study steady-state and balanced growth and to determine mutation and recombination frequencies in stationary phase.

Articulated Halkieriids from the Lower Cambrian of North Greenland and their Role in Early Protostome Evolution

Abstract: Articulated halkieriids of Halkieria evangelista sp. nov. are described from the Sirius Passet fauna in the Lower Cambrian Buen Formation of Peary Land, North Greenland. Three zones of sclerites are recognizable: obliquely inclined rows of dorsal palmates, quincuncially inserted lateral cultrates and imbricated bundles of ventro-lateral siculates. In addition there is a prominent shell at both ends, each with radial ornamentation. Both sclerites and shells were probably calcareous, but increase in body size led to insertion of additional sclerites but marginal accretion of the shells. The ventral sole was soft and, in life, presumably muscular. Recognizable features of internal anatomy include a gut trace and possible musculature, inferred from imprints on the interior of the anterior shell. Halkieriids are closely related to the Middle Cambrian Wiwaxia, best known from the Burgess Shale: this clade appears to have played an important role in early protostome evolution. From an animal fairly closely related to Wiwaxia arose the polychaete annelids; the bundles of siculate sclerites prefigure the neurochaetae whereas the dorsal notochaetae derive from the palmates. Wiwaxia appears to have a relic shell and a similar structure in the sternaspid polychaetes may be an evolutionary remnant. The primitive state in extant polychaetes is best expressed in groups such as chrysopetalids, aphroditaceans and amphinomids. The homology between polychaete chaetae and the mantle setae of brachiopods is one line of evidence to suggest that the latter phylum arose from a juvenile halkieriid in which the posterior shell was first in juxtaposition to the anterior and rotated beneath it to provide the bivalved condition of an ancestral brachiopod. H. evangelista sp. nov. has shells which resemble those of a brachiopod; in particular the posterior one. From predecessors of the halkieriids known as siphogonuchitids it is possible that both chitons (polyplacophorans) and conchiferan molluscs arose. The hypothesis of halkieriids and their relatives having a key role in annelid-brachiopod-mollusc evolution is in accord with some earlier proposals and recent evidence from molecular biology. It casts doubt, however, on a number of favoured concepts including the primitive annelid being oligochaetoid and a burrower, the brachiopods being deuterostomes and the coelom being an archaic feature of metazoans. Rather, the annelid coelom arose as a functional consequence of the transition from a creeping halkieriid to a polychaete with stepping parapodial locomotion.

Aging in a magnetic particle system.

Abstract: The influence of dipolar interaction in a frozen ferrofluid has been experimentally studied. The ferrofluid consisted of particles of $\ensuremath{\gamma}$- ${\mathrm{Fe}}_{2}$${\mathrm{O}}_{3}$ with mean diameter 70 \AA{}. Four samples with volume concentration of magnetic particles ranging from 0.03% to 17% have been investigated. The magnetic relaxation of the most concentrated particle system shows typical spin glass dynamics at low temperature, e.g., the relaxation depends on the time spent at constant temperature before applying the magnetic field---the system ages. The most diluted sample shows isolated particle dynamics and no aging.

Isolated Congenital Complete Atrioventricular Block in Adult Life A Prospective Study

Abstract: Background The prognosis of congenital complete atrioventricular block (CCHB) is usually considered favorable in adults This belief is based on studies comprising a limited number of patients and with rather short observation times In the present study, the natural history of the disease was investigated by a prospective follow-up through decades of adult life of patients with a large group having well-defined CCHB without structural heart disease Methods and Results The diagnostic criteria of CCHB proposed by Yater were applied Patients registered as having CCHB in 1964, supplemented by younger patients all without symptoms during their first 15 years of life, were selected The study was limited to patients with isolated, complete, permanent block An interview was conducted with all patients and clinical follow-up data obtained There were finally 102 patients, 61 women and 41 men In November 1994, the time of observation, after the age of 15 years in survivors, was between 7 and 30 years The mea

Isothiocyanates as substrates for human glutathione transferases : structure-activity studies

Abstract: The catalytic properties of four human glutathione transferases (GSTs), A1-1, M1-1, M4-4 and P1-1, were examined with 14 isothiocyanate (R-NCS) substrates. The compounds include aliphatic and aromatic homologues, some of which are natural constituents of human food, namely sulphoraphane [1-isothiocyanato-4-(methylsulphinyl)butane], erucin [1-isothiocyanato-4-(methylthio)butane], erysolin [1-isothiocyanato-4-(methylsulphonyl)butane], benzyl-NCS, phenethyl-NCS and allyl-NCS. All isothiocyanates investigated were substrates for the four GSTs. The enzymes promote addition of the thiol group of GSH to the electrophilic central carbon of the isothiocyanate group to form dithiocarbamates [R-NH-C(=S)-SG] which have high UV absorption at 274 nm. Molar absorption coefficients and non-enzymic rate constants as well as standardized enzyme assay conditions for all compounds were established. Of the four isoenzymes investigated, GSTs M1-1 and P1-1 were generally the most efficient catalysts, whereas GST M4-4 was the least efficient. Isothiocyanates are among the GST substrates that are most rapidly conjugated. On the basis of rate-enhancement data and binding energies, the isothiocyanates were compared with 4-hydroxyalkenals, another class of natural GST substrates previously subjected to systematic kinetic analysis. The incremental transition-state stabilization attributable to an increased number of methylene groups in homologous alkyl isothiocyanates is similar to that previously noted for homologous 4-hydroxyalkenals.

cDNA cloning of prophenoloxidase from the freshwater crayfish Pacifastacus leniusculus and its activation.

Abstract: Prophenoloxidase (proPO), an enzyme that is the terminal component of the so-called proPO activating system, a defense and recognition system in crustaceans and insects, has been purified and cloned from a crayfish blood cell cDNA library. The deduced amino acid sequence codes for a polypeptide with a mass of 80,732 Da, which is close to 76 kDa, the apparent mass of the purified enzyme. proPO contains two copper atoms, and two putative copper-binding sites were found in the deduced amino acid sequence. Sequence comparisons show that these putative copper-binding sites are similar to the corresponding sites in arthropod hemocyanins and also, although the sequence similarities are less extensive, similar to tyrosinases from vertebrates and microorganisms. The purified enzyme is a typical tyrosinase because it hydroxylates monophenols and oxidizes o-diphenols but does not oxidize p-diphenols. If a homogeneous preparation of crayfish proPO were incubated with a homogeneous sample of the proPO activating enzyme, a serine proteinase, the cleavage of proPO by this trypsin-like enzyme was found to occur between Arg-176 and Thr-177.