Showing papers by "Ghent University published in 1993"

Development of a 5-step multi-chamber reactor as a simulation of the human intestinal microbial ecosystem

Abstract: A five-stage reactor was developed to simulate the gastro-intestinal microbial ecosystem of humans The small intestine was simulated by a two-step “fill and draw” system, the large intestine by a three-step reactor A representative supply medium was developed to support a microbial community resembling that of the human gastro-intestinal tract The entire system was validated by monitoring fermentation fluxes and products, ie indicator bacterial groups, volatile fatty acids, enzymatic activities and headspace gases The simulator was operated with varying concentrations and combinations of arabinogalactan, xylan, pectin, dextrins and starch The resulting patterns of microbial diversity and activity were analyzed and compared with data for in-vivo gastro-intestinal microbial communities as described in the literature and found to be reprensentative

cdc2a expression in Arabidopsis is linked with competence for cell division.

Abstract: A key regulator of the cell cycle is a highly conserved protein kinase whose catalytic subunit, p34(cdc2), is encoded by the cdc2 gene. We studied the control of the expression of the Arabidopsis cdc2a gene in cell suspensions and during plant development. In cell cultures, arrest of the cell cycle did not significantly affect cdc2a mRNA levels, but nutrient conditions were important for cdc2a expression. During plant development, the pattern of cdc2a expression was strongly correlated with the cell proliferation potential. The effects of external signals on cdc2a expression were analyzed. Wounding induced expression in leaves. Lack of light altered temporal regulation of cdc2a in the apical but not root meristem of seedlings. Differential cdc2a responses were obtained after different hormone treatments. Signals present only in intact plants were necessary to mediate these responses. Although other control levels have yet to be analyzed, these results suggest that the regulation of cdc2a expression may contribute greatly to spatial and temporal regulation of cell division in plants. Our results also show that cdc2a expression is not always coupled with cell proliferation but always precedes it. We propose that cdc2a expression may reflect a state of competence to divide, and that the release of other controls is necessary for cell division to occur.

Oxidative stress and ageing in Caenorhabditis elegans.

Abstract: Mutations in the age-1 gene double both the mean and maximum life span of Caenorhabditis elegans. They also result in an age-specific increase of catalase and Cu/Zn superoxide dismutase activity levels. The higher superoxide dismutase activity levels in age-1 mutants confer hyperresistance to the superoxide-anion-generating drug paraquat. The rate of superoxide anion production by microsome fractions declines linearly with age in age-1(+) worms, but, after an initial decline, is stabilized at a higher level in senescent age-1 mutant nematodes. These results clearly show that oxidative stress resistance and potential life span are correlated in this organism, and they suggest that the natural product of age-1 either directly or indirectly downregulates the activities of several other genes as a function of age.

Pectin, pectinase and protopectinase: production, properties, and applications

Abstract: Publisher Summary This chapter discusses the applications, properties, and production of pectin, pectinase, and protopectinase. Pectic substances are acid polysaccharides of high molecular weight that are widespread in the plant kingdom. The size, charge density, charge distribution, and degree of substitution of pectin molecules may be changed biologically or chemically. The pectins in these beverages are considered to be responsible for the “veloute” or “moeilleux” (softness or silkiness), which give the fruit product its particular character. The pectin production process consists mainly of an acid extraction, followed by a (partial) purification of the extract and, eventually, precipitation and drying. However, this process has several disadvantages that are addressed in the chapter. Research has been initiated with the aim of developing an improved alternative microbial pectin production process by means of a specific enzyme. The chapter also deals with a specific enzyme, called “protopectinase,” which solubilizes protopectin forming highly polymerized soluble pectin.

Microbial degradation of poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in soils.

Abstract: The microbial degradation of tensile test pieces made of poly(3-hydroxybutyrate) [P(3HB)] or copolymers with 10% [P(3HB-co-10%3HV)] and 20% [P(3HB-co-20%3HV)] 3-hydroxyvaleric acid was studied in small household compost heaps. Degradation was measured through loss of weight (surface erosion) and changes in molecular weight and mechanical strength. It was concluded, on the basis of weight loss and loss of mechanical properties, that P(3HB) and P(3HB-co-3HV) plastics were degraded in compost by the action of microorganisms. No decrease inMw could be detected during the degradation process. The P(3HB-co-20%3HV) copolymer was degraded much faster than the homopolymer and P(3HB-co-10%3HV). One hundred nine microbial strains capable of degrading the polymersin vitro were isolated from the samples used in the biodegradation studies, as well as from two other composts, and identified. They consisted of 61 Gram-negative bacteria (e.g.,Acidovorax facilis), 10 Gram-positive bacteria (mainlyBacillus megaterium), 35Streptomyces strains, and 3 molds.

Attenuated luteinizing hormone (LH) pulse amplitude but normal LH pulse frequency, and its relation to plasma androgens in hypogonadism of obese men.

Abstract: To evaluate the effects of obesity on the hypothalamo-pituitary-testicular axis, we compared total and free (FT) testosterone (T), androstenedione, dehydroepiandrosterone and its sulfate, and 5 alpha-androstane-3 alpha, 17 beta-diol glucuronide, and estradiol levels in a group of 35 obese [body mass index (BMI), > 30] men (aged 17-61 yr) to levels in a nonobese control group. We observed a highly significant negative correlation (P < 0.001) between plasma (F)T levels and BMI and a significant positive correlation (P < 0.01) between E2 levels and BMI. There were no differences between the obese and the nonobese men in levels of androstenedione, dehydroepiandrosterone sulfate, and 5 alpha-androstane-3 alpha, 17 beta-diol glucuronide. Insulin levels were significantly higher in obese men and were significantly (P < 0.02) correlated with the waist hip girth ratio. To evaluate the role of the hypothalamo-pituitary complex in the decreased (F)T levels in obese men, diurnal (0800-2000 h) LH pulsatility was studied in eight obese middle-aged men and eight age-matched controls. The pulsatility of plasma cortisol levels was also studied. Whereas LH pulse frequency was similar in the obese and control subjects, mean diurnal LH levels, mean diurnal LH pulse amplitude, and the sum of all diurnal LH pulse amplitudes and secretory masses were significantly lower in the obese than in the controls. Moreover, there was a highly significant correlation between the sum of LH pulse amplitudes and plasma (F)T levels. This decrease in LH pulse amplitude is not an isolated phenomenon of hypothalamo-pituitary dysfunction in obese men, because the pulse amplitude of plasma cortisol levels was also decreased. The decreased LH pulse amplitude together with the normal respond of Leydig cells to hCG stimulation reported in the literature suggest by inference that the decreased FT levels in obese men are the consequence of a hypogonadotropism. The decreased LH pulse amplitude and the decreased amplitude of cortisol pulses, and hence probably of ACTH pulses, point toward a general alteration of hypothalamo-pituitary function in obese men.

Deletion of the paired alpha 5(IV) and alpha 6(IV) collagen genes in inherited smooth muscle tumors

Abstract: The gene encoding alpha 6(IV) collagen, COL4A6, was identified on the human X chromosome in a head-to-head arrangement and within 452 base pairs of the alpha 5(IV) collagen gene, COL4A5. In earlier studies, intragenic deletions of COL4A5 were detected in a subset of patients with Alport syndrome (AS), a hereditary defect of basement membranes. In some families, AS cosegregates with diffuse leiomyomatosis (DL), a benign smooth muscle tumor diathesis. Here it is shown that patients with AS-DL harbor deletions that disrupt both COL4A5 and COL4A6. Thus, type IV collagen may regulate smooth muscle differentiation and morphogenesis.

A high-resolution sensor based on tri-aural perception

Abstract: The authors present a high-resolution sensor composed of three ultrasonic sensors, one transmitter/receiver and two extra receivers, which allows a significant improvement in the information-extraction process. With this sensor the position (distance and bearing) of all isolated objects in an approximately 25 degrees field of view can be determined using information contained in one single snapshot of a moderately complex scene. Within limits, the sensor system can also discriminate between different types of reflectors, in particular, walls and edges, based on their radius of curvature. These results are all based on the determination of the arrival times of the echoes present at the three receivers. A noise model that accounts for the measured variations of the arrival times is used to derive limits on the resolution of the results provided by the sensor. Based on this model it is shown that, to a large extent, the sensor results are impervious to measurement variations common to all three receivers. Results obtained in a realistic environment are compared with those obtained from a conventional time-of-flight sensor. >

Molecular characterization of the proteinase‐encoding gene, prb1, related to mycoparasitism by Trichoderma harzianum

Abstract: Summary The soil fungus Trichoderma harzianum is a mycoparasitic fungus known for its use as a biocontrol agent of phytopathogenic fungi. Among other factors, Trichoderma produces a series of antibiotics and fungal cell wall-degrading enzymes. These enzymes are believed to play an important role in mycoparasitism. Among the hydrolytic enzymes, we have identified a basic proteinase (Prb1) which is induced by either autoclaved mycelia, fungal cell wall preparation or chitin; however, the induction does not occur in the presence of glucose. The proteinase was purified and biochemically characterized as a serine proteinase of 31 kDa and pl 9.2. Based on the sequence of three internal peptides, synthetic oligonudeotide probes were designed. These probes allowed subsequent isolation of a cDNA and its corresponding genomic clone. The deduced amino acid sequence indicates that the proteinase is synthesized as a pre-proenzyme and allows its classification as a serine proteinase. Northen analysis shows that the induction of this enzyme is due to an increase in the corresponding mRNA level.

Osmoregulation of a Pyrroline-5-Carboxylate Reductase Gene in Arabidopsis thaliana

Abstract: In Arabidopsis thaliana (L.) Heynh. proline can account for up to 20% of the free amino acid pool after salt stress. Proline accumulation occurs in plants mainly by de novo synthesis from glutamate. The last step of the proline biosynthetic pathway is catalyzed by pyrroline-5-carboxylate (P5C) reductase. A gene (AT-P5C1) encoding this enzyme in A. thaliana has been cloned and sequenced. Expression of AT-P5C1 in Escherichia coli resulted in the complementation of a proC mutant to prototrophy. A comparison of the AT-P5C1 primary and secondary structures with those of six P5C reductases of other organisms is presented. With the exception of several functionally important amino acid residues, little conservation in the primary structure is seen; much greater similarity exists in the putative secondary structure. The AT-P5C1 protein is probably cytosolic. Under normal growth conditions, the P5C reductase mRNA level was significantly higher in roots and ripening seeds than in green tissue. A salt treatment of A. thaliana plants resulted in a 5-fold induction of the AT-P5C1 transcript, suggesting osmoregulation of the AT-P5C1 promoter region. Moreover, a time-course experiment indicated that this induction precedes proline accumulation.

Riemerella anatipestifer gen. nov., comb. nov., the causative agent of septicemia anserum exsudativa, and its phylogenetic affiliation within the Flavobacterium-Cytophaga rRNA homology group

Abstract: The phylogenetic position of the causative agent of septicemia anserum exsudativa, now most often referred to as [Moraxella] anatipestifer (brackets indicate a generically misnamed taxon) or “[Pasteurella] anatipestifer,” was established by performing rRNA cistron similarity studies. [Moraxella] anatipestifer belongs to rRNA superfamily V, together with the genera Flavobacterium, Cytophaga, Flexibacter, Weeksella, Capnocytophaga, and Sphingobacterium. The detailed structure of rRNA superfamily V, which now contains five major rRNA homology groups, is described. An analysis of various phenotypic parameters, including new data (cellular proteins and fatty acids) and previously published data (respiratory quinones, enzyme activities, and classical phenotypic features), revealed that [Moraxella] anatipestifer differs in many aspects from its closest relatives, Flavobacterium indologenes, Flavobacterium gleum, Flavobacterium indoltheticum, Flavobacterium balustinum, Flavobacterium meningosepticum, and Weeksella zoohelcum. The combined genotypic and phenotypic data indicate that this organism should be placed in a separate genus; the name Riemerella anatipestifer gen. nov., comb. nov. is proposed for this bacterium. The specific epithet anatipestifer is kept in order to avoid nomenclatural confusion. However, it should be emphasized that the illness caused by this organism is a septicemic disease which is not restricted to ducks.

Short and long-term effects of growth hormone treatment on bone turnover and bone mineral content in adult growth hormone-deficient males.

Abstract: Summary OBJECTIVE In view of the fact that GH-deficient adults present with pronounced osteopaenia and can be considered at risk for osteoporotic fractures, we wanted to investigate the effects of biosynthetic GH replacement therapy (0.25 IU/kg/week) on biochemical indices of bone turnover and on bone mineral content (BMC) in a group of GH-deficient adult males. DESIGN We performed a 6-month randomized, double-blind, placebo-controlled study, followed by 12–24 months of GH treatment in all patients. PATIENTS Twenty adult males with GH deficiency of childhood onset were studied. MEASUREMENTS We measured serum IGF-I, serum phosphate, biochemical indices of bone turnover (serum alkaline phosphatase activity, serum osteocalcin, serum carboxyterminal propeptide of type-I procollagen, fasting urinary hydroxyproline/creatinine and calcium/creatinine ratios) and bone mineral content, measured at the forearm and the lumbar spine by single and dual-photon absorptiometry respectively. RESULTS After 3 and 6 months of GH administration, the serum levels of alkaline phosphatase, osteocalcin and carboxyterminal propeptide of type-I procollagen, and the fasting urinary hydroxyproline/creatinine ratio were significantly increased compared to placebo-treated patients (P<0.01 to P<0.001). During the open study phase, the values for these indices of bone turnover remained elevated above pretreatment levels (P<0 01 to P<0 001 at 12 months), a downward trend becoming apparent after about one year of GH treatment. BMC values showed an initial decline after 3 months of GH treatment (most likely due to an expansion of the remodelling space), followed by a significant and progressive increase above pretreatment values, reaching 7–8% for total BMC at the lumbar spine (L2-L4) and 9–9% for total BMC at the forearm, after 30 months of GH administration. CONCLUSIONS The data of our study show that administration of substitutive doses of growth hormone to GH-deficient adult males activates bone turnover for a period of at least one year and suggests that this may have a beneficial effect on bone mass in these patients.

Porcine respiratory coronavirus: molecular features and virus-host interactions.

Abstract: Since 1984, a previously unrecognized respiratory coronavirus, causing a mostly unapparent infection, has rapidly and massively spread within the swine population in Europe, and few years later, a virus with similar characteristics has been identified in the USA. The agent, designated PRCV, appears to be derived from the porcine enteric coronavirus TGEV. The aim of the present article is to review comprehensively the state of the knowledge about this new virus and its infection. The review includes the following topics: epizootiology, molecular characterization and antigenic features of PRCV, pathogenesis and clinical aspects, immunity and laboratory diagnosis. The authors' views concerning the impact of the emergence of PRCV on both coronavirus research and swine production are presented in the conclusion.

Identification and Classification of Lactobacillus Acidophilus, L. Gasseri and L. Johnsonii Strains by SDS-PAGE and rRNA-Targeted Oligonucleotide Probe Hybridization

Abstract: Summary: Thirty-two strains originally identified as Lactobacillus acidophilus and L. gasseri were screened for their taxonomic homogeneity by SDS-PAGE of whole-cell proteins. After numerical comparison of the resulting protein electrophoretic fingerprints, two well-delineated clusters were detected. The majority of the strains grouped in one electrophoretic cluster, which contained the type strain of L. acidophilus and corresponds to DNA group A1 of Johnson, J. L., Phelps, C. F., Cummins, C. S., London, J. & Gasser, F. (1980; International Journal of Systematic Bacteriology 30, 53–68). Another cluster corresponded to DNA group B. It contained two subclusters, which agreed perfectly with DNA subgroups B1 (L. gasseri) and B2 (L. johnsonii), respectively. The 23S rRNA genes were partially sequenced and 23S-rRNA-targeted oligonucleotide probes were designed for identification of DNA groups A1, B1 and B2. Probe Lbg reacted with all strains of electrophoretic cluster B1 (L. gasseri), probe Lbj hybridized with strains of cluster B2 (L. johnsonii) and probe Lba with strains of cluster A1 (authentic L. acidophilus). The probes were successfully used for the identification of strains belonging to the respective species. The phylogenetic relationship of a representative of L. johnsonii was determined by comparative sequence analysis of the 16S rRNA genes. It is very closely related to L. gasseri.

Assembly of an antibody and its derived antibody fragment in Nicotiana and Arabidopsis

Abstract: The yield and assembly of an IgG1 antibody and its derived Fab fragment were compared inNicotiana andArabidopsis. The results obtained showed a lot of interclonal variability. For 45% of the primary transgenic calluses, antigen-binding entities represented less than 0.1% of the total soluble protein (TSP). Only two of the 103 analysed transformants contained more than 1% of antigen-binding protein, with 1.26% being the highest yield. Analogous amounts of complete antibody and Fab accumulated in primary callus tissue. Moreover, yields were in the same range for both species as far as primary callus tissue is concerned. However, the accumulation of the Fab fragment in leaf tissue of regenerated plants differed significantly betweenNicotiana andArabidopsis. The Fab fragment accumulated to only 0.044% of TSP inNicotiana leaves but up to 1.3% inArabidopsis leaves. Furthermore, both species showed differences in the assembly pattern of the complete antibody. WhereasArabidopsis contained primarily fully assembled antibodies of 150 kDa,Nicotiana showed an abundance of fragments in the 50 kDa range.

Redox-activated expression of the cytosolic copper-zinc superoxide-dismutase gene in nicotiana

Abstract: Superoxide dismutases (SODs; superoxide: superoxide oxidoreductase, EC 11511) play a key role in protection against oxygen radicals, and SOD gene expression is highly induced during environmental stress To determine the conditions of SOD induction, the promoter of the cytosolic copper/zinc SOD (Cu/ZnSODcyt) gene was isolated in Nicotiana plumbaginifolia and fused to the beta-glucuronidase reporter gene Oxidative stress is likely to alter the cellular redox in favor of the oxidized status Surprisingly, the expression of the Cu/ZnSODcyt gene is induced by sulfhydryl antioxidants such as reduced glutathione, cysteine, and dithiothreitol, whereas the oxidized forms of glutathione and cysteine have no effect It is therefore possible that reduced glutathione directly acts as an antioxidant and simultaneously activates the Cu/ZnSODcyt gene during oxidative stress

The Relationship of Career Mentoring to Early Career Outcomes

Abstract: This study examines the relationship of career mentoring to the promotions, compensation and satisfaction of 148 early career managers and professionals in Belgium. The results support the conclusion that career mentoring is particularly related to early career promotion histories, to general work satisfaction and career satisfaction. Career mentoring was unrelated to total compensation. These results occurred even after controlling for a variety of factors identified by Pfeffer (1977) and Whitely et al. (1991). Several reasons are provided for the relationship between career mentoring and these early career outcomes. The results suggest a number of areas for future career mentoring research.

Three unusual modifications, a D-arabinosyl, an N-methyl, and a carbamoyl group, are present on the Nod factors of Azorhizobium caulinodans strain ORS571.

Abstract: Azorhizobium caulinodans strain ORS571 is a symbiont of the tropical legume Sesbania rostrata. Upon nod gene induction with naringenin, strain ORS571 secretes into the culture medium Nod factors that morphologically change the host plant--in particular, deformed root hairs (Hai/Had) and meristematic foci are formed at the basis of lateral roots. The latter infrequently develop further into nodule-like structures. The azorhizobial Nod factors are chitin tetramers or pentamers, N-acylated at the nonreducing-end glucosamine with either vaccenic acid (C18:1) or stearic acid (C18:0). They, thus, resemble the previously described Nod factors from (brady)rhizobia. The backbone lipooligosaccharide is substituted with unusual modifications, presumably involved in host-specificity determination. There is a D-arabinose branch on the reducing end and an N-methyl and O-carbamoyl substitution on the nonreducing end of the oligosaccharide chain. The previously identified nod gene nolK may be involved in the synthesis of a D-arabinose derivative. The nodS gene product is probably responsible for the N-methylation of Nod factors.

Water-facilitated transport of bacteria in unsaturated soil columns: Influence of cell surface hydrophobicity and soil properties

Abstract: The numbers of bacteria, surface applied to soil columns which were subsequently irrigated, decreased exponentially with depth. The numbers of surface-inoculated bacteria decreased by a factor of 10 every 1.1–6.0 cm of soil depth after irrigating the columns with 5cm of water at a rate of 2.5cm h−1. Major differences were observed between the examined test strains. The migration of hydrophobic strains was 2–3 times slower compared to that of hydrophilic strains. This was correlated with an increased adhesion of the hydrophobic strains to soil particles. Increasing the bulk density of the soil from 1.27 to 1.37 g cm−3 reduced the volume of the pores with a diameter of 16–30 μm by ca 80%. This corresponded with a decrease in the migration of bacteria by 30–60%. Migration was reduced by ca 40–80% in a sandy soil mixed with 20% clay soil. The reduction was more pronounced for hydrophilic bacteria.

The Arabidopsis 1-Aminocyclopropane-1-Carboxylate Synthase Gene 1 Is Expressed during Early Development.

Abstract: The temporal and spatial expression of one member of the Arabidopsis 1-aminocyclopropane-1-carboxylate (ACC) synthase gene family (ACS1) was analyzed using a promoter-[beta]-glucuronidase fusion. The expression of ACS1 is under developmental control both in shoot and root. High expression was observed in young tissues and was switched off in mature tissues. ACS1 promoter activity was strongly correlated with lateral root formation. Dark-grown seedlings exhibited a different expression pattern from light-grown ones. The ACC content and the in vivo activity of ACC oxidase were determined. ACC content correlated with ACS1 gene activity. ACC oxidase activity was demonstrated in young Arabidopsis seedlings. Thus, the ACC formed can be converted into ethylene. In addition, ethylene production of immature leaves was fourfold higher compared to that of mature leaves. The possible involvement of ACS1 in influencing plant growth and development is discussed.

Cloning, expression in Escherichia coli, and characterization of cellulolytic enzymes of Azoarcus sp., a root-invading diazotroph.

Abstract: We screened members of a new genus of grass-associated diazotrophs (Azoarcus spp.) for the presence of cellulolytic enzymes. Out of five Azoarcus strains representing different species, only in the endorhizosphere isolate BH72, which is also capable of invading grass roots, was significant endoglucanase activity, in addition to beta-glucosidase and cellobiohydrolase activity, present. Reducing sugars were readily released from medium-viscosity carboxymethylcellulose (CMC), but neither CMC, cellulose filter strips, Avicel, cellobiose, nor D-glucose served as the sole carbon source for growth of Azoarcus spp. Clones from a plasmid library of strain BH72 expressed all three enzymes in Escherichia coli, apparently not from their own promoter. According to restriction endonuclease mapping and subclone analysis, beta-glucosidase and cellobiohydrolase activities were localized on a single 2.6-kb fragment not physically linked to a 1.45-kb fragment from which endoglucanase (egl) was expressed. Two isoenzymes of endoglucanase probably resulting from proteolytic cleavage had pI values of 6.4 and 6.1 and an apparent molecular mass of approximately 36 kDa. Cellobiohydrolase and beta-glucosidase activity were conferred by one enzyme 41 kDa in size with a pI of 5.4, which we classified as an unspecific exoglycanase (exg) according to substrate utilization and specificity mapping; hydrolysis of various oligomeric substrates differentiated it from endoglucanase, which degraded substituted soluble cellulose derivatives but not microcrystalline cellulose. Both enzymes were not excreted but were associated with the surface of Azoarcus cells. Both activities were only slightly influenced by the presence of CMC or D-glucose in the growth medium but were enhanced by ethanol. egl was located on a large transcript approximately 15 kb in size, which was detectable only in cells grown under microaerobic conditions on N2. Surface-bound exo- and endoglucanases with some unusual regulatory features, detected in this study in a strain which is unable to metabolize cellulose or sugars, might assist Azoarcus sp. strain BH72 in infection of grass roots.

In vitro cytogenetic effects of 2450 MHz waves on human peripheral blood lymphocytes

Abstract: Cytogenetic analyses were performed on human peripheral blood lymphocytes exposed to 2450 MHz microwaves during 30 and 120 min at a constant temperature of 36.1 degrees C (body temperature). The temperature was kept constant by means of a temperature probe put in the blood sample which gives feedback to a microcomputer that controls the microwave supply. We found a marked increase in the frequency of chromosome aberrations (including dicentric chromosomes and acentric fragments) and micronuclei. On the other hand the microwave exposure did not influence the cell kinetics nor the sister chromatid exchange (SCE) frequency.

Subgingival Minocycline Hydrochloride Ointment in Moderate to Severe Chronic Adult Periodontitis: A Randomized, Double‐Blind, Vehicle‐Controlled, Multicenter Study

Abstract: The safety and efficacy of subgingivally-applied 2% minocycline ointment was evaluated in a randomized, double-blind study of 103 adults with moderate to severe periodontitis. Two groups were compared; one received the test minocycline ointment and the other a vehicle control. Both groups had scaling and root planing at baseline, after which the test or control ointments were applied with an applicator into the periodontal pockets at baseline, and at 2, 4, and 6 weeks. Assessment of clinical response was made by measuring probing depth and probing attachment level and gingival bleeding. These measurements were made at baseline prior to scaling and root planing, and at weeks 4 and 12. Microbiological assessment of the subgingival flora was carried out with DNA probes at baseline, and at weeks 2, 4, 6, and 12 to identify and quantify Porphyromonas gingivalis, Prevotella intermedia, and Actinobacillus actinomycetemcomitans. Subgingival minocycline ointment resulted in statistically significantly greater reduction of P. gingivalis at weeks 2, 4, 6, and 12; P. intermedia at weeks 2, 4, 6, and 12; and A. actinomycetemcomitans at weeks 6 and 12. Probing depth reductions were seen for both groups at weeks 4 and 12; however, this reduction was statistically significantly greater in subjects treated with minocycline ointment. Reduction in gingival index and probing attachment gain were seen in both groups, however, the differences between the groups were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Environment, human reproduction, menopause, and andropause.

Abstract: As the hypothalamic gonadotropin-releasing hormone (GnRH) pulse generator is an integrator of hormonal, metabolic, and neural signals, it is not surprising that the function of the hypothalamogonadal axis is subject to the influence of a large array of environmental factors. Before puberty, the central nervous system (CNS) restrains the GnRH pulse generator. Undernutrition, low socioeconomic status, stress, and emotional deprivation, all delay puberty. During reproductive life, among peripheral factors that effect the reproductive system, stress plays an important role. Stress, via the release of corticotropin-releasing factor (CRF), eventually triggered by interleukin 1, inhibits GnRH release, resulting in hypogonadism. Effects of CRF are probably mediated by the opioid system. Food restriction and underweight (anorexia nervosa), obesity, smoking, and alcohol all have negative effects on the GnRH pulse generator and gonadal function. Age and diet are important determinants of fertility in both men and women. The age-associated decrease in fertility in women has as a major determinant chromosomal abnormalities of the oocyte, with uterine factors playing a subsidiary role. Age at menopause, determined by ovarian oocyte depletion, is influenced by occupation, age at menarche, parity, age at last pregnancy, altitude, smoking, and use of oral contraceptives. Smoking, however, appears to be the major determinant. Premature menopause is most frequently attributable to mosaicism for Turner Syndrome, mumps ovaritis, and, above all, total hysterectomy, which has a prevalence of about 12-15% in women 50 years old. Premature ovarian failure with presence of immature follicles is most frequently caused by autoimmune diseases or is the consequence of irradiation or chemotherapy with alkylating cytostatics. Plasma estrogens have a physiological role in the prevention of osteoporosis. Obese women have osteoporosis less frequently than women who are not overweight. Early menopause, suppression of adrenal function (corticoids), and thyroid hormone treatment all increase the frequency of osteoporosis. Aging in men is accompanied by decreased Leydig cell and Sertoli cell function, which has a predominantly primary testicular origin, although changes also occur at the hypothalamopituitary level. Plasma testosterone levels, sperm production, and sperm quality decrease, but fertility, although declining, is preserved until senescence. Stress and disease states accelerate the decline on Leydig cell function. Many occupational noxious agents have a negative effect on fertility.(ABSTRACT TRUNCATED AT 400 WORDS)

Zinc affects siderophore-mediated high affinity iron uptake systems in the rhizosphere Pseudomonas aeruginosa 7NSK2.

Abstract: Zinc concentrations ranging between 0.1 and 1 mM only slightly reduced maximal growth of wild-type Pseudomonas aeruginosa 7NSK2 in iron-limiting casamino acid medium, but had a clear negative effect on the growth of mutant MPFM1 (pyoverdin negative) and especially mutant KMPCH (pyoverdin and pyochelin negative). Production of pyoverdin by wild-type strain 7NSK2 was significantly increased in the presence of 0.5 mM zinc and could not be repressed by iron even at a concentration of 100 microM. Siderophore detection via isoelectrofocusing revealed that mutant KMPCH did not produce any siderophores, while mutant MPFM1 overproduced a siderophore with an acidic isoelectric point, most likely pyochelin. Pyochelin production by MPFM1 was stimulated by the presence of zinc in a similar way as pyoverdin for the wild-type. Analysis of outer membrane proteins revealed that three iron regulated outer membrane proteins (IROMPs) (90, 85 and 75 kDa) were induced by iron deficiency in the wild-type, while mutants were found to have altered IROMP profiles. Zinc specifically enhanced the production of a 85 kDa IROMP in 7NSK2, a 75 kDa IROMP in MPFM1 and a 90 kDa IROMP in KMPCH.