bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics of coaggregation of Porphyromonas gingivalis with Fusobacterium nucleatum using an automated microtiter plate assay
Authors: Metzger Z. , Featherstone L. G. , Ambrose W. W. , Trope M. , Arnold R. R.
Published: March 2003

Coaggregation between Porphyromonas gingivalis and Fusobacterium nucleatum strains was previously studied using either a semi‐quantitative macroscopic assay or radioactive tracer assays. A new automated microtiter plate assay is introduced, in which the plate reader (Vmax) was adapted to allow quantitative evaluation of the kinetics of coaggregation. F nucleatum PK 1594 coaggregated with P. gingivalis HG 405 with a maximal coaggregation rate of 1.05 mOD/min, which occurred at a P. gingivalis to F. nucleatum cell ratio of 1 to 2. F. nucleatum PK 1594 failed to do so with P. gingivalis strains A 7436 or ATCC 33277. Galactose inhibition of this coaggregation could be quantitatively measured over a wide range of concentrations to demonstrate its dose‐dependent manner. P. gingivalis HG 405 failed to coaggregate with F. nucleatum strains ATCC 25586 and ATCC 49256. The assay used in the present study is a sensitive and efficient quantitative automated tool to study coaggregation and may replace tedious radioactive tracer assays.
Detection and rapid increase of salivary antibodies to Staphylococcus lentus, an indigenous bacterium in rabbit saliva, through a single tonsillar application of bacterial cells
Authors: Kanda M. , Inoue H. , Fukuizumi T. , Tsujisawa T. , Tominaga K. , Fukuda J.
Published: March 2003

In rabbits, Staphylococcus lentus is one of the major bacteria in saliva and a minor bacteria in jejunum fluids and nasal wash. The presence and induction of naturally occurring antibodies reacting to rabbit indigenous bacteria were studied. In non‐immune rabbits, the proportion of anti–S. lentus IgA antibodies to total IgA in the saliva was several times higher than that in the intestinal fluids and the nasal wash. The salivary antibodies were found to have increased 1 week after a single tonsillar application of isolated S. lentus cells but not after a single nasal application or a single intragastric instillation. In addition, the anti–S. lentus antibodies in the saliva highly increased with weekly tonsillar applications of isolated S. lentus but increased only one‐fifth with weekly nasal applications of the same cells. These results strongly suggest that the palatine tonsils, which we believe had already been sensitized by S. lentus in the physiological condition, induced naturally occurring antibodies in rabbit saliva.
Human salivary immunoglobulin and antigen‐specific antibody activity after tonsillectomy
Authors: Childers N. K. , Powell W. D. , Tong G. , Kirk K. , Wiatrak B. , Michalek S. M.
Published: March 2003

The importance of the lymphoid tissue collectively known as Waldeyer’s ring, which includes the palatine, lingual and nasopharyngeal tonsils, in the induction and contribution of specific antibody responses in human saliva is not clear. The purpose of this study was to determine whether salivary immunoglobulin A (IgA) levels differ in quantity and quality between subjects who have had a tonsillectomy and age, sex and race‐matched controls. Parotid saliva, whole saliva, and blood serum samples were collected from 25 volunteer children who had undergone tonsillectomy (T−) within 6–14 months of sampling and from 25 age, sex and race‐matched controls. The levels of total IgA (and subclasses) in saliva, and of antigen‐specific salivary IgA and serum IgA and IgG antibodies to 4–9 relevant antigens were analyzed by ELISA. No significant difference was observed in the mean total IgA and IgA subclass levels in parotid and whole saliva, although the mean levels for children with a T− were slightly lower. Children with a T− had significantly higher parotid salivary IgA and IgA1 specific/total activity than controls. The total and specific whole saliva IgA and the specific serum IgA or IgG activities were not significantly different from controls. These results indicate an association between the removal of tonsils and increased levels of specific IgA activity in parotid saliva within the first year after a T−.
Utilization and acid production of β‐galactosyllactose by oral streptococci and human dental plaque
Authors: Hata S. , Hata H. , Kanou N. , Saito T. , Kamiyama K. , Mayanagi H.
Published: March 2003

β‐Galactosyllactose is a trisaccharide containing the β‐galactosidic linkage at the nonreducing end. The purpose of this study was to determine whether certain oral streptococci could utilize four kinds of β‐galactosyllactoses. Three of four β‐galactosyllactoses were unable to support growth of the oral streptococci and to be a substrate for producing acid from the cell suspensions and dental plaque. 4′‐β‐Galactosyllactose supported growth of Streptococcus sanguis ATCC 35105, ATCC 49298, Streptococcus mitis ATCC 15914, Streptococcus oralis ATCC 35037, ATCC 10557 and Streptococcus milleri 10707 and produced acid from dental plaque. Although β‐galactosidase activities were observed in all the strains, 4′‐β‐galactosyllactose could not be used as a carbon source for the growth of mutans streptococci. Enzymes metabolizing 4′‐β‐galactosyllactose were induced when S. oralis ATCC 10557 was cultured in medium containing galactose. These results suggested that 4′‐β‐galactosyllactose could be as cariogenic as lactose if it is consumed frequently and retained for a long period in the mouth.
Expression and roles of herpesvirus entry mediators A and C in cells of oral origin
Authors: Hung S.‐L. , Cheng Y.‐Y. , Wang Y.‐H. , Chang K.‐W. , Chen Y.‐T.
Published: March 2003

The roles of viral glycoprotein D (gD) and cellular herpesvirus entry mediators A (HveA) and C (HveC) in herpes simplex virus entry into oral cells were determined. Studies with purified truncated forms of gD‐1, HveA and HveC indicated that these molecules may be involved in herpes simplex virus entry into oral cells. Moreover, HveA was expressed similarly in primary cultures of gingival keratinocytes and fibroblasts, whereas HveC was expressed at higher levels in gingival keratinocytes, as determined by RT‐PCR and immunocytochemical staining. Further analysis using immunohistochemistry demonstrated that both HveA and HveC were expressed in epithelial cells, fibroblasts and vascular endothelial cells in gingival tissues. However, only HveC was detected in nerve fibers. Also, HveA was detected throughout the epidermis, whereas HveC was pronounced in the strata basale and spinosum. In conclusion, this study characterized HveA and HveC, molecules that may participate in entry of herpes simplex virus into oral cells.
Culture conditions for the detection of allergen‐specific T‐cell reactivity in cord blood: Influence of cell number
Authors: Kopp Matthias V. , Pichler Josefa , Halmerbauer Gerhard , Kuehr Joachim , Frischer Thomas , Urbanek Radvan , Szépfalusi Zsolt
Published: March 2003

Raised T‐cell proliferation of cord blood mononuclear cells (CBMC) in response to various ingestant and inhalant allergens has been reported in newborns, suggesting a prenatal allergen contact. In general, for in vitro proliferation assays a concentration of 50 × 103 or 100 × 103 cells/well are used. The aim of this study was to analyze whether cell concentration influences T‐cell reactivity in cord blood cells and to study differences of T‐cell reactivity triggered by inhalant and ingestant allergens. CBMC from 51 neonates (34 females: 22 with and 29 without a family history of allergy, i.e. FH+ or FH–) were incubated with interleukin‐2 (IL‐2), β‐lactoglobulin (β‐LG), ovalbumin (OVA), house dust mite allergen Dermatophagoides pteronyssinus (Der p 1), and timothy grass allergen Phleum pratense (Phl p 1) for 7 days. The cell concentration ranged from 62.5 × 103 to 100 × 103 cells/well. Proliferation was assessed by incorporation of [3H]‐thymidine and was expressed as counts per minute (c.p.m.). In unstimulated cells, a decreasing cell concentration paralleled a steep drop of background activity. In response to IL‐2, a decreasing cell concentration led to a slow decrease of c.p.m. The corresponding mean stimulation indices (SI) were 9, 32, 77, 47, and 21 for 100 × 103, 50 × 103, 25 × 103, 12.5 × 103, and 62.5 × 103 cells/well, respectively. In addition, the highest number of positive proliferative responses to specific allergens were obscured at lower cell concentrations. For β‐LG, the maximal number of positive responses were obtained between 25 × 103 (n = 44) and 12.5 × 103 (n = 46) cells/well, for OVA at 25 × 103 (n = 3) cells/well, for Der p 1 at 50 × 103 (n = 5) cells/well, and for Phl p 1 between 25 × 103 and 12.5 × 103 (n = 5) cells/well. Positive proliferation in at least one of the tested assays was observed in 100% of samples in response to β‐LG, in 22% in response to Phl p 1, and in 14% in response to OVA and Der p 1. T‐cell reactivity did not differ between samples of newborns with or without a family history of atopy. Therefore, sensitivity of T‐cell proliferation measurement is highly influenced by background proliferation of unstimulated cells. Hence, proliferation assays with lower cell numbers unmask T‐cell reactivity in response to ingestant and inhalant allergens. We suggest the use of concentrations of 12.5 × 103–50 × 103 cells/well in proliferation experiments.
Intervention models on psycho‐social health in families with an asthmatic child
Authors: Gustafsson Dan , Olofsson Niclas , Andersson Florence , Lindberg Berit , Schollin Jens
Published: March 2003

Despite an increase in the prevalence of asthma during the last few decades, the need for hospital treatment of children with asthma has become less. One reason for this is that children and their parents are now more involved in the treatment of the disease, and responsibility has been shifted from the medical care system to the family. This new responsibility may cause increased psycho‐social tension within the family. We conducted a pilot study on three limited methods of intervention to find the best way to help families in this respect. All three methods (individual family meetings, family group meetings, and evaluation of the child's environment in school) reduced the psycho‐social burden of having a child with asthma. This indicates that families should be supported by being given the opportunity to participate in meetings to discuss the disease or to have the environment in the child's school evaluated, in addition to receiving regular medical care.
Diet, infection and wheezy illness: lessons from adults
Authors: Seaton Anthony , Devereux Graham
Published: March 2003

An increase in asthma and atopic disease has been recorded in many countries where society has become more prosperous. We have investigated two possible explanations: a reduction in childhood infections and a change in diet. In a cohort of people followed up since 1964, originally selected as a random sample of primary school children, we have investigated the relevance of family size and the common childhood infectious diseases to development of eczema, hay fever and asthma. Although membership of a large family reduced risks of hay fever and eczema (but not asthma), this was not explained by the infections the child had suffered. Indeed, the more infections the child had had, the greater the likelihood of asthma, although measles gave a modest measure of protection. We have investigated dietary factors in two separate studies. In the first, we have shown the risks of bronchial hyper‐reactivity are increased seven‐fold among those with the lowest intake of vitamin C, while the lowest intake of saturated fats gave a 10‐fold protection. In the second, we have shown that the risk of adult‐onset wheezy illness is increased five‐fold by the lowest intake of vitamin E and doubled by the lowest intake of vitamin C. These results were supported by direct measurements of the vitamins and triglycerides in plasma. We have proposed that changes in the diet of pregnant women may have reflected those observed in the population as a whole and that these may have resulted in the birth of cohorts of children predisposed to atopy and asthma. The direct test of this is to study the diet and nutritional status of a large cohort of pregnant women and to follow their offspring forward. This is our current research.
Family interaction and a supportive social network as salutogenic factors in childhood atopic illness
Authors: Gustafsson Per A. , Kjellman N. ‐I. Max , Björkstén Bengt
Published: March 2003

The role of psycho‐social factors in the development of allergy was studied prospectively in 82 infants with a family history of atopy. The family participated in a standardized family test when the children were 18 months old. The ability to adjust to demands of the situation (‘adaptability’), and the balance between emotional closeness and distance (‘cohesion’), were assessed from videotapes by independent raters. Families rated as functional in both of these aspects were classified as ‘functional’, otherwise as ‘dysfunctional’. The social network, life events, atopic symptoms (based on postal inquiries regarding symptoms answered by the parents, and on physical examinations), psychiatric symptoms, and socio‐economic circumstances of the families were evaluated when the children were 18 months and 3 years of age. The children were classified as atopic (asthmatic symptoms or eczema) or as non‐atopic. All but two children with atopic disease at 3 years of age had atopic disease before 18 months of age, while 32 of 60 children with atopic disease at 18 months of age had no problems by 3 years of age. An unbalanced family interplay at 18 months was associated with a relative risk (RR) of 1.99 for continuing atopic illness at 3 years of age (1.18 < RR < 3.37, p = 0.01). There was a weak positive confounding effect for smoking (RR reduced by 7%), eczema on three or more localizations (RR reduced by 4.5%), and the amount of cat allergen in household dust (RR reduced by 3%). Recovery from atopic illness between 18 months and 3 years of age was four times as probable in families with functional interaction and a good social supportive network when children were 18 months of age, than in dysfunctional families with a poor social network (74% versus 20% p < 0.01). Children with asthmatic symptoms showed more signs of emotional distress than did healthy children (p = 0.02). Dysfunctional family interaction patterns were more commonly observed in families of children who at 3 years of age still had atopic symptoms, than in children who had recovered. The patterns included expression of emotion and reaction to the needs of others, alternating between total disinterest and over‐involvement (p = 0.02), lack of support and rejection of offered support (p = 0.01), a greater number of individual decisions without regard to the other family members (p = 0.04), and indistinct ‘generational boundaries’ (p = 0.04). We conclude that psychosocial factors, such as family interaction and a supportive social network, play a significant role in the course of atopic illness in early childhood and that measures which enhance family interaction and the social network could influence the course of the disease favorably.
Exposure to pets and allergies in children
Authors: Hölscher Bernd , Frye Christian , Wichmann H. ‐Erich , Heinrich Joachim
Published: March 2003

Currently, there is ongoing discussion regarding potential protective effects of exposure to pets during early childhood on the development of atopic disorders in children later in life. We used data from three consecutive cross‐sectional surveys to study the relationship between contact with dogs, cats and other pets, and allergic diseases in schoolchildren 5–14 years of age. In three study areas of the former East Germany, 7,611 questionnaires were received from 5,360 different children who were examined between 1992 and 1999 as school entrants, or third‐ or sixth‐graders. Allergic sensitization to common aeroallergens (birch, grass, mite, cat) was assessed by specific serum immunoglobulin E (IgE) concentrations [using radioallergosorbent testing (RAST)] for 85% of the children. After adjustment for possible confounders, inverse associations were found between contact with dogs in the first year of life and lifetime prevalences of asthma [odds ratio (OR) = 0.68; 95% confidence interval (CI): 0.43–1.08], hay fever (OR = 0.61; 95% CI: 0.39–0.95), eczema (OR = 0.76; 95% CI: 0.61–0.94), itchy rash (OR = 0.76; 95% CI: 0.61–0.94), and pollen sensitization (RAST ≥ 4: OR = 0.56; 95% CI: 0.38–0.82). These effects were more pronounced for children with atopic parents. Similar associations were observed for current contact with dogs. We identified no clear relationships for the other pets (cats, rodents, birds), with the exception that children currently exposed to cats were more likely to be sensitized against cats. In conclusion, this study supports the hypothesis of a potential protective mechanism related to dog exposure in early life, especially for children of atopic parents. However, this association was found only for dogs and not for cats.
Successful transplantation of a cadaveric kidney with post‐infectious glomerulonephritis
Authors: Mizuiri S. , Shigetomi Y. , Sugiyama K. , Miyagi M. , Hatano T. , Tajima E. , Aikawa A. , Ohara T. , Kawamura S. , Hasegawa A.
Published: March 2003

Abstract: This report describes a successful renal Tx in a patient with chronic renal failure, caused by dysplastic kidneys, who received a cadaveric kidney with post‐infectious glomerulonephritis. Sequential renal biopsies were performed at 12 h before Tx, and at 1 h and on days 8 and 58 post‐Tx. Post‐operative hematuria disappeared on day 9 and proteinuria on day 13. Normal graft function was observed within 1 month, with histologic resolution. Our study suggests that while the donor kidney facilitates deposition of certain immune reactants, this is a host (environmental) problem and when transplanted into a new host (new environment), the problem is no longer sustained.
Epstein–Barr virus‐associatedpost‐transplant lymphoproliferative disease after bone marrow transplantation mimicking graft‐versus‐host disease
Authors: Claviez Alexander , Tiemann Markus , Wagner Hans‐joachim , Dreger Peter , Suttorp Meinolf
Published: March 2003

Abstract: In contrast to solid organ transplantation (Tx), the incidence of post‐transplant lymphoproliferative disease (PTLD) after hematopoietic stem cell Tx (HSCT) is generally low. This risk, however, is significantly elevated in patients receiving human leukocyte antigen (HLA) mis‐matched or T‐cell‐depleted grafts, or after treatment for severe graft‐versus‐host disease (GvHD). An 18‐yr‐old patient with positive Epstein–Barr virus (EBV) serology received a fully matched, unmanipulated bone marrow graft from an unrelated EBV‐positive donor for treatment of acute myeloid leukemia (AML) in second complete remission. GvHD prophylaxis was performed with cyclosporin A (CsA) and a short course of methotrexate. Four months after Tx, the patient developed ulcerative tonsillitis that was unresponsive to antibiotic treatment. Diarrhea appearing simultaneously was interpreted as gastrointestinal GvHD and steroids were added to CsA. A few days later the patient was admitted to hospital because of generalized seizure and pneumonia. Despite reduction of immunosuppression, intensification of anti‐viral treatment, and subsequent mechanical ventilation, the patient died of acute respiratory distress 6 days later. Autopsy demonstrated disseminated EBV‐induced, multi‐nodular lymphoma infiltration of the entire colon but no signs of GvHD. Moreover, both lungs, paratracheal lymph nodes, kidneys, thyroid gland, and liver were infiltrated with large B‐cell non‐Hodgkin’s lymphomas. This case underlines the rapid and aggressive course of EBV‐induced disseminated PTLD after HSCT, initially mimicking intestinal GvHD because of massive colonic lymphoma infiltration. Tissue biopsies should be performed early for establishing correct diagnosis, thus enabling specific therapy, e.g. infusion of donor leukocytes with cytotoxic T‐lymphocytes.
Successful ribavirin therapy for life‐threatening laryngeal papillomatosis post liver transplantation
Authors: Balauff Antje , Sira Jaswant , Pearman Ken , McKiernan Patrick , Buckels John , Kelly Deirdre
Published: March 2003

Abstract: A 3‐yr‐old girl developed severe progressive juvenile laryngeal papillomatosis (JLP) 2 yr after liver transplantation (Tx) for biliary atresia. The papillomata were resistant to withdrawal of immunosuppression, to laser surgery, and to subcutaneous interferon (3 MU/m2, three times weekly), necessitating tracheostomy. Oral ribavirin therapy (25 mg/kg/day) in combination with no immunosuppression effectively prevented the rapid recurrence of JLP over 5 yr. Hence, oral ribavirin is a potentially useful therapy in this life‐threatening situation and may also be of benefit in other children with severe JLP.
Hepatic osteodystrophy in chronic cholestasis: Evidence for a multifactorial etiology
Authors: Klein Gordon L. , Soriano Humberto , Shulman Robert J. , Levy Moise , Jones Glenville , Langman Craig B.
Published: March 2003

Abstract:Children with cholestatic liver disease have been thought to develop hepatic osteodystrophy resulting from vitamin D and calcium malabsorption, resulting in secondary hyperparathyroidism and osteomalacia or rickets. However, treatment with vitamin D has not always proven successful in improving the bone disturbance. The aim of our study was to determine the role of vitamin D deficiency in the pathogenesis of hepatic osteodystrophy. We studied five patients, three female and two male, ages 0.9–19 yr, with biopsy‐proven chronic cholestatic liver disease and previously low serum levels of vitamin D despite oral intake of vitamin D preparations. Patients were admitted to the Clinical Research Center for 8 days for sunlight deprivation and ultraviolet light substitution and for determinations of serum 25‐hyroxyvitamin D(25(OH)) D2and ‐D3, osteocalcin, and type I collagen telopeptide (ICTP), the last two being markers of bone formation and resorption, respectively. Samples were taken on admission, at discharge, and 1 month later. Results demonstrated low serum levels of osteocalcin and normal circulating levels of ICTP. Admission serum 25(OH)D2levels were uniformly low or undetectable and remained so. Admission levels of circulating 25(OH)D3were normal or low and did not rise during ultraviolet light therapy or subsequent resumption of oral vitamin D therapy and remained low 1 month later. These results indicate that in the face of low–normal to low total 25(OH)D levels, the low osteocalcin and normal ICTP levels suggest that decreased bone formation and not increased bone resorption is the main determinant of bone loss in a subset of children with chronic cholestatic liver disease.
Unusual presentation of central nervous system relapse with oculomotor nerve palsy in a case of CD56‐positive acute myeloid leukemia following allogeneic stem cell transplantation
Authors: Haase R. , Wiegand P. , Hirsch W. , Meyer‐Bahlburg A. , Diwan X. , Wawer A. , Burdach S.
Published: March 2003

Abstract: Allogeneic stem cell transplantation (allo‐SCT) plays an important role in the treatment of infants and children with acute myelogenous leukemia (AML). Leukemic relapse after allo‐SCT is responsible for a high rate of treatment failure. Extra‐medullary relapse (EMR), without involvement of bone marrow, is rare compared to medullary relapse. CD56, the neural cell adhesion molecule, may contribute to the higher frequency of CNS relapse in CD56‐positive AML. We observed an isolated EMR on the oculomotor nerve of a 17‐month‐old girl 12 weeks after cord blood transplantation (CBT), who was transplanted because of CD56‐positive AML. Diagnosis of relapse was suspected clinically and confirmed by magnetic resonance imaging (MRI), and fluorescence‐activated cell sorter (FACS) and chimerism analysis of cerebrospinal fluid (CSF). Therapy consisted of intra‐thecal chemotherapy, CNS irradiation, and systemic immunomodulation by cyclosporin A (CsA) and basiliximab withdrawal. Twenty‐one months after relapse, the patient shows full remission of symptoms and previously described oculomotor nerve infiltration.
The relationship between serum creatinine, serum cystatin C and glomerular filtration rate in pediatric renal transplant recipients: A pilot study
Authors: Krieser David , Rosenberg Andrew R. , Kainer Gad ,   Daya Naidoo
Published: March 2003

Abstract: Serum cystatin C more accurately reflects glomerular filtration rate (GFR) in pediatric renal transplant recipients than serum creatinine. Nineteen pediatric renal transplant recipients, 15 male and 4 female, ranging in age from 8.35 yr to 19.06 yr (median 13.52 yr), were enrolled in the study over an 18‐month period. Twenty‐eight measurements of 99mTc‐DTPA GFR were compared with simultaneous measurements of serum cystatin C and Cr. Linear regression analysis, Pearson correlation coefficients and analysis of variance (anova) were used to determine the relationship between creatinine, cystatin C and GFR. The correlation coefficients (R2) for the relationship of 1/Cr to DTPA‐GFR and for 1/cystatin C to DTPA‐GFR were 0.63 and 0.58, respectively. There was no significant difference between serum cystatin C and serum creatinine as markers of GFR. Serum cystatin C, which costs more to measure than serum creatinine, offers no advantage in monitoring the renal function of pediatric renal transplant recipients.
Pediatric liver transplantation in metabolic disease: Clinical decision making
Authors: Shneider Benjamin L.
Published: March 2003

Abstract: Proper utilization of liver transplantation in the management of pediatric metabolic diseases requires a comprehensive understanding of both metabolic disease and the risk and benefits of transplantation. This brief review focuses on issues that pertain to the treatment of tyrosinemia type I, bile acid biosynthesis disorders, primary hyperoxaluria, Crigler‐Najjar Type I, and mitochondrial diseases. These entities are used as prototypes to illustrate many of the principles that are applied in a more general sense to the management of metabolic diseases. The natural history of these disorders are considered in the context of the risks of liver transplantation. Indications, contraindications, and both current and future alternatives to transplantation, are considered.
Steroid‐refractory graft‐vs.‐host disease: past, present and future
Authors: Carpenter Paul A. , Sanders Jean E.
Published: March 2003

Abstract: Despite current standard preventive strategies that include optimizing donor selection and the combination of methorexate and a calcineurine inhibitor, acute and chronic GVHD remains a major barrier to successful hematopoietic cell transplantation for a sizeable proportion of patients. When acute and chronic GVHD become manifest a standard primary therapy approach has been the addition of glucocorticoid therapy to a background of calcineurine inhibition. When this approach fails patients with GVHD require secondary therapy. Ideally, second‐line agents should promote transplantation tolerance so that the morbidity associated with prolonged use of glucocorticoids and other immunosuppressive agents can be minimized. Promising new agents or strategies which warrant further controlled clinical trials include: mycophenolate mofetil, sirolimus, humanized or chimeric monoclonal antibodies such as visilizumab, daclizumab and infliximab, and extracorporeal photopheresis. Co‐operative studies are necessary to hasten the process of evaluating novel treatment strategies for acute and chronic GVHD.
Heat shock in mechanically wounded carrot root disks causes destabilization of stable secretory protein mRNA and dissociation of endoplasmic reticulum lamellae
Authors: Brodl Mark R. , Ho Tuan‐hua David
Published: March 2003

In many organisms, the synthesis of heat shock proteins during heat shock is concomitant with the cessation of at least a portion of normal cellular protein synthesis. Heat shocked barley aleurone layers selectively stop the synthesis and secretion of secretory proteins. Exposure to 40°C causes a disruption of endoplasmic reticulum (ER) lamellae, which we have hypothesized leads to the destabilization of otherwise stable mRNA previously associated with ER‐bound polyribosomes. We report here that this was also observed in wounded carrot (Daucus carota L.) root parenchyma tissue which synthesizes and secretes cell wall proteins when mechanically wounded. Nondenaturing cationic polyacrylamide gel electrophoresis of radiolabeled proteins indicated that heat shock caused the cessation of the synthesis and secretion of extensin, a hydroxyproline‐rich cell wall glycoprotein. Northern blot analyses indicated that the mRNA levels for both extensin and another cell wall protein (p33) were rapidly diminished during heat shock. Under nonheat shock conditions extensin mRNA had a half‐life of greater than 4 h, but this appeared to be reduced to less than 30 min during heat shock. There was also a concomitant dissociation of ER lamellae in wounded, heat shocked carrot root tissue, as observed by transmission electron microscopy. These observations indicate that this response may be universal among plant secretory tissues.
O2 regulation and O2‐limitation of nitrogenase activity in root nodules of pea and lupin
Authors: Castillo Leonor Diaz del , Hunt Stephen , Layzell David B.
Published: March 2003

The gas exchange characteristics of intact attached nodulated roots of pea (Pisum sativum cv. Finale X) and lupin (Lupinus albus cv. Ultra) were studied under a number of environmental conditions to determine whether or not the nodules regulate resistance to oxygen diffusion. Nitrogenase activity (H2 evolution) in both species was inhibited by an increase in rhizosphere pO2 from 20% to 30%, but recovered within 30 min without a significant increase in nodulated root respiration (CO2 evolution). These data suggest that the nodules possess a variable barrier to O2 diffusion. Also, nitrogenase activity in both species declined when the roots were either exposed to an atmosphere of Ar:O2 or when the shoots of the plants were excised. These declines could be reversed by elevating rhizosphere pO2, indicating that the inhibition of nitrogenase activity resulted from an increase in gas diffusion resistance and consequent O2‐limitation of nitrogenase‐linked respiration. These results indicate that nodules of pea and lupin regulate their internal O2 concentration in a manner similar to nodules of soybean, despite the distinct morphological and biochemical differences that exist between the nodules of the 3 species. Experiments in which total nitrogenase activity (TNA = H2 production in Ar:O2) in pea and lupin nodules was monitored while rhizosphere pO2 was increased gradually to 100%, showed that the resistance of the nodules to O2 diffusion maintains nitrogenase activity at about 80% of its potential activity (PNA) under normal atmospheric conditions. The O2‐limitation coefficient of nitrogenase (OLCN= TNA/PNA) declined significantly with prolonged exposure to Ar:O2 or with shoot excision. Together, these results indicate a significant degree of O2‐limitation of nitrogenase activity in pea and lupin nodules, and that yields may be increased by realizing full potential activity.
Isolation and analysis of gas bubbles in the cavities of Azolla leaves
Authors: Uheda Eiji , Kitoh Shunji , Dohmaru Takaaki , Shiomi Nobuyuki
Published: March 2003

A procedure has been developed for the isolation of gas bubbles from the cavities of leaves of Azolla rubra. Mature leaves of exponentially growing Azolla plants were carefully cut under water with a razor blade. The gas bubbles in the cavities were driven out by a stream of water running from a glass capillary and collected in another capillary that was filled with distilled water. This allowed the collection of a sufficient number of gas bubbles for analysis. The concentration of oxygen in the gas obtained was slightly lower than that in the external air. The diffusion of external 15N2 into the gas bubbles was low. The concentration of 15N2 in gas bubbles was only 2% of that of the external air even after incubation of Azolla plants in 15N2 in light or in darkness for 20 h.

The method described here for isolation and analysis of gas bubbles should permit further studies of the properties of the gas bubbles in the cavities of Azolla leaves.
A comparative study of DNA synthesis in cotyledon protoplast cultures of Brassica napus, B. campestris and B. oleracea using an immunocytochemical technique
Authors: Zhao Kong‐Nan
Published: March 2003

The present study was designed (1) to observe the characterization of 5‐bromo‐2′‐dexoyuridine (BrdU) incorporation into cultured Brassica cotyledon protoplasts and (2) to investigate the genetic differences in the levels of nuclear DNA synthesis (expressed by the percentage of nuclei labelled with BrdU) in cotyledon protoplast cultures from 12 cultivars of three Brassica species (Brassica napus, B. campestris and B. oleracea) at an early stage using immunocytochemistry. Nuclei labelled with BrdU were different from those showing only staining with 4′‐6′‐diamidino‐2‐phenylindole (DAPI) under fluorescence and light microscopy. Two to 5% of nuclei were labelled with BrdU after 1 h of culture, indicating that nuclear DNA synthesis occurred at a very early stage of culture. The percentage of nuclei labelled with BrdU increased with time over the length of the culture period. The mean percentage of nuclei labelled with BrdU in the 12 cultivars was about 25% at 24 h after culture initiation. The curve of the increase in percentage of nuclei labelled with BrdU exhibited an S‐shape from 1 to 24 h. However, cultivar differences in percentages of nuclei labelled with BrdU were very significant over the time course of 1‐24 h from initial culture, with cultivars Eureka (B. napus), Global (B. napus), Narc 82 (B. napus), Bunyip (B. campestris) and Sugar Loaf (B. oleracea) having a consistently higher percentage of nuclei labelled with BrdU than the other cultivars. Species differences were also significant, with cultivars of B. napus showing much higher percentages than the tested cultivars of B. campestris and B. oleracea. The results indicate that the differences in nuclear DNA synthesis in Brassica cotyledon protoplast cultures were most likely at both intra‐ and interspecies levels.
Purification and properties of thiamine‐binding proteins from sesame seed
Authors: Shimizu Mayumi , Inaba Kazunari , Yoshida Toyokazu , Toda Takayoshi , Iwashima Akio , Mitsunaga Toshio
Published: March 2003

Three thiamine‐binding proteins of 17‐19 kDa (STBP‐I, II, and III) were purified from sesame seed (Sesamum indicum L.). Each of the proteins was composed of two subunits of equal molecular mass and each subunit consisted of a large polypeptide and a small polypeptide linked by a disulfide bond(s). They were rich in glutamic acid (or glutamine) and arginine. Their binding activities were optimal at neutral pH. They bound specifically free thiamine but not thiamine phosphates. STBP‐I had higher affinity for thiamine than STBP‐II or STBP‐III. STBP‐II and STBP‐III bound one molecule of thiamine per molecule, and STBP‐I bound 0.5 molecule. The amino acid composition and structure of the STPBs were similar to those of 2S storage proteins.
Sucrose metabolism during endosperm development in wheat (Triticum aestivum)
Authors: Riffkin H. L. , Duffus C. M. , Bridges I. C.
Published: March 2003

This work reports changes in sucrose synthase and invertase activities throughout endosperm development in wheat, together with the associated substrates and metabolites, sucrose, UDP, glucose, fructose and UDP‐glucose. Throughout endosperm development, sucrose synthase had consistently higher activity than invertase and indeed invertase activity did not change appreciably. The observed variation in pattern and amounts of glucose and fructose present during the mid‐ and late stages of endosperm development confirmed the suggestion that invertase was not the preferred pathway of sucrose catabolism. Kinetic parameters for sucrose synthase were determined in crude extracts. Estimates of UDP and sucrose concentrations suggest that sucrose synthase is unlikely to achieve its potential maximum velocity. This limitation may however be overcome in part by the apparent excess catalytic activity measured during endosperm development.
Effects of synthetic peptides on thylakoid phosphoprotein phosphatase reactions
Authors: Cheng Lüling , Stys Dalibor , Allen John F.
Published: March 2003

A synthetic peptide analogue of the phosphorylation site of LHC II, when phosphorylated by thylakoid membranes, served as a substrate for the thylakoid phosphoprotein phosphatase. The phosphopeptide became dephosphorylated at a low rate, comparable to that of the 9 kDa phosphoprotein. Phospho‐LHC II itself became dephosphorylated much more rapidly, at a rate unaffected by endogenous phosphorylation of the peptide. Endogenous phosphorylation of the peptide was also without effect on other thylakoid protein phosphorylation and dephosphorylation reactions. In contrast, dephosphorylation of many thylakoid phosphoproteins was inhibited by addition of a pure, chemically‐synthesised phosphopeptide analogue of phospho‐LHC II. This result suggests that at least one thylakoid phosphoprotein phosphatase exhibits a broad substrate specificity. The results indicate that any one of a number of amino acid sequences can give a phosphoprotein configuration that is recognised by a single phosphatase.
Photoperiodic responses of a northern and southern ecotype of black cottonwood
Authors: Howe Glenn T. , Hackett Wesley P. , Furnier Glenn R. , Klevorn Richard E.
Published: March 2003

Photoperiod is an important signal controlling the onset of dormancy in perennial plants. Short days typically induce growth cessation, the initiation of cold acclimation, the formation of a terminal bud. bud dormancy and other adaptive responses. Photoperiodic ecotypes have evolved in many species with large latitudinal distributions. The photoperiodic responses of two northern (53°35′ and 53°50′N) and two southern (34°10′ and 40°32′N) genotypes of black cottonwood (Populus trichocarpa Torr. & Gray) were characterized by growing trees under a range of photoperiods in the greenhouse and growth chamber. Short days induced bud set in both ecotypes. resulting in trees with fewer leaves and less height growth than trees grown under long days. Short days also enhanced anthocyanin accumulation in the northern ecotype and decreased branching of the southernmost genotype. Two aspects of the photoperiodic response were evaluated for each trail: critical photoperiod. which was defined as the longest photoperiod that elicited a short‐day response, and photoperiodic sensitivity, which was defined as the change in response per unit change in photoperiod. For each of the traits analyzed, the northern ecotype had a longer critical photoperiod and greater photoperiodic sensitivity than did the southern ecotype. The short critical photoperiod and reduced photoperiodic sensitivity of the southern ecotype resulted in a significant delay in bud set compared to that of the northern ecotype, even under a 9‐h photoperiod. Typically, photoperiodic ecotypes have been characterized as having different critical photoperiods. Ecotypic differences in photoperiodic sensitivity, however, indicate that differences in the photoperiodic response curves cannot be completely described by the critical photoperiod alone. These results also suggest that the critical photoperiod. photoperiodic sensitivity and speed of bud set have a common physiological basis. Bud set occurred earlier hi the northern ecotype primarily because bud scale leaves were initiated earlier. For one of the northern genotypes, leaf primordia that were initialed under long days subsequently differentiated into bud scale leaves after the trees were transferred to a 9‐h photoperiod. This demonstrates that primordia initiated under long days are not necessarily committed to becoming foliage leaves. The response to photoperiod did not differ appreciably between the greenhouse and growth chamber conditions that were tested.
Ultrastructure and some plasma membrane characteristics of ozone‐exposed loblolly pine needles
Authors: Anttonen Seija , Sutinen Marja‐Liisa , Heagle Allen S.
Published: March 2003

Tropospheric ozone is a widespread and phytotoxic air pollutant in the industrialized world and causes reduced growth in many tree species. It is therefore important that, for example, the responses of the economically important loblolly pine to ozone are determined thoroughly. The objective of the study was to determine changes in ultrastructure, the vanadate‐sensitive ATPase activity of the plasma membrane, the fatty acids of plasma membrane phospholipids, visible injury, and growth in loblolly pine (Pinus taeda L.) needles exposed to different concentrations of ozone in open‐top chambers. The treatments were charcoal filtered air (CF), nonfiltered air (NF), or NF‐air with ozone added for 12 h daily at 1.5‐ or 2‐fold ambient ozone concentrations from May to October, 1993. Visible injury was more severe in the high than in the low ozone treatments. Growth of needles of the first flush of 1993 was significantly reduced in the highest ozone treatment. Two types of ultrastructural injury, characterized as either acute or chronic, were observed in mesophyll cells under elevated ozone. The acute injury lead to cell collapse and death. The chronic injury, characterized by several symptoms, e.g. decreased chloroplast size and increased density of the stroma, was also found in the NF ozone treatment. Increased density of chloroplast stroma and swelling of thylakoids were transient symptoms, suggesting partial recovery as ozone concentrations decreased in fall. Ozone induced decreases in the specific activity of vanadate‐sensitive ATPase of plasmalemma and in the degree of unsaturation in phospholipid fatty acids. The detected reduced needle growth, ultrastructural injury and perturbations in the function and composition of the plasma membrane indicate susceptibility of loblolly pine to ozone. Changes in the plasma membrane phospholipids may have contributed to the decrease in ATPase activity. Injury to the key enzyme of the plasma membrane can directly affect intracellular processes. In the long‐term, decreased viability of needles can lead to reductions in loblolly pine productivity.
Phytochrome research in whole plant physiology. Wild‐type seedlings versus mutants and transgenic plants
Authors: De Greef Jan A.
Published: March 2003

In this report I comment on a small selection of the many interesting papers presented at the European Symposium on Photomorphogenesis in Plants. My major concern arises from problems relating to classical phytochrome treatments versus mutants and transgenic plants as tools in photomorphogenic research on whole plant physiology. Plant responses to visible light are especially evident in etiolated seedlings, although they occur throughout the life cycle of the plant. These characteristics of plant photomorphogenesis in nature can be viewed as representing a continuous developmental series of graded responses to subsequent light exposures. Where the individual, photoautotrophic seedling is moving through this developmental gradient depends on its particular light environment, that is, on both the quality and the quantity of light to which the seedling is exposed. On the contrary, phytochrome treatment of mutants and transgenic seedlings having either deficiency or overexpression of photoreceptors will result in an aberrant kind of physiology.
Identification and purification of the calcium‐regulated Ca2+‐ATPase from the endoplasmic reticulum of a higher plant mechanoreceptor organ
Authors: Liß Harald , Bockelmann Christian , Werner Nicola , Fromm Hillel , Weiler Elmar W.
Published: March 2003

Erythrosin b, a potent inhibitor of the Ca2+‐ATPases and the Ca2+‐release channel (BCC1) in mechanosensitive tissue of Bryonia dioica Jacq., effectively suppresses a tendril's reaction to touch, suggesting that Ca2+‐transporters are involved in signal transduction in this organ. The Ca2+‐ATPase located in the endoplasmic reticulum (ER) represents a multiregulated enzyme that is stimulated by calmodulin (CaM), KCl and lysophospholipids. Limited proteolysis of ER‐membranes by trypsin results in an irreversible activation of the Ca2+‐ATPase and loss of the CaM sensitivity, presumably through removal of an autoinhibitory domain where CaM binds. Mild trypsination mimics the effects of CaM on Vmax and the affinity for Ca2+ and ATP. Irrespective of a trypsin treatment, the enzyme can be additionally stimulated by KCl and lysolipids, indicating that the sites of interaction for these effectors are not located in the domain removed by the protease. CaM‐stimulated ATPase activity was purified from microsomal and ER fractions using a combination of CaM‐affinity and anion‐exchange chromatography. The isolated polypeptide was enzymatically active, showed a calcium‐dependent mobility‐shift in SDS‐PAGE from 109 kDa in the absence of Ca2+ to 104 kDa in the presence of 10 mM CaCl2 and could be radiolabeled with [35S]‐CaM. The characteristics of the purified enzyme remained closely similar to those of the ER‐bound Ca2+‐transporting activity, including the enzymatic data, CaM stimulation, and the sensitivity towards a range of inhibitors.
Distribution of cadmium in leaves of cadmium tolerant and sensitive ecotypes of Silene vulgaris
Authors: Chardonnens Agnes N. , Ten Bookum Wilma M. , Kuijper Lothar D. J. , Verkleij Jos A. C. , Ernst Wilfried H. O.
Published: March 2003

It has been postulated that vacuolar compartmentation might play an important role in naturally selected cadmium tolerance in Silene vulgaris (Moench.) Garcke (Bladder campion). Additionally, a tendency of heavy metals to accumulate in the epidermis has been reported. Since these factors would affect the distribution of cadmium in leaves, we determined the distribution of cadmium in leaves of cadmium tolerant and sensitive ecotypes of Silene vulgaris at different levels of exposure and at different time intervals. Cadmium concentrations were higher in leaves of sensitive plants than in those of cadmium tolerant ones after identical exposure to cadmium for a period of 8 days. The highest cadmium concentrations were found in the lower epidermis of plants of both ecotypes. The amount of cadmium located at the lower epidermis was highest for sensitive plants, although the stomatal density was lower in the sensitive ecotype than in the tolerant one. A possible explanation for this phenomenon is the weak relationship between transpiration (water flow) and element allocation. Our results support the hypothesis that vacuolar storage of cadmium plays an important role in the mechanism of cadmium tolerance in Silene vulgaris.