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Biomedical subjects

M Griffith

Publications and source records attributed to M Griffith.

At least 37 records · Page 2Linked to original sources

Childhood cancer incidence in a cohort of twin babies.

We studied childhood cancer incidence in a population-based twin cohort using record linkage to the National Registry of Childhood Tumours. After correcting for mortality, an incidence deficit was observed (Standardized Incidence Ratio (SIR) 79; 95% Confidence Interval (CI) 39-120). Pooled analysis with data from published cohort studies indicates a similar significant incidence reduction (SIR 81, 95% CI 67-96). Further studies are warranted.

Child↗

Relationship between antifreeze protein and freezing resistance in Pseudomonas putida GR12-2.

Following transposon Tn5 mutagenesis of the plant growth-promoting rhizobacterium Pseudomonas putida GR12-2, mutants that have different freeze-resistant properties were selected. Five of the freeze-sensitive mutants, i.e. FSM-5, -6, -14, -29, and -41, secreted a lower amount of antifreeze protein-(AFP) into the culture broth compared with the wild-type. Among of these five mutants, the three mutants (FSM-6, FSM-14, and FSM-41) that have the lowest level of freezing resistance (4.0-6.0% survival) also produce AFP at low levels (0.5-0.9 microg/mL) compared with the wild-type (4.8 microg/ml). The antifreeze and ice-nucleating activities of the AFP from these three mutant strains were similar to those of wild-type. Furthermore, the decreased freezing resistance from three mutants could be partially restored by adding purified AFP to mutant cell suspensions. Freezing resistance of three mutants was found to increase in proportion to the addition of AFP up to a concentration of 50 microg/mL. We conclude that accumulation of AFP is one component of the mechanism for freezing resistance in bacteria.

Antifreeze Proteins↗

Breast tumor contamination of PBSC harvests: tumor depletion by positive selection of CD34(+) cells.

BACKGROUND: Positive selection of CD34(+) cells may reduce or eliminate tumor cells contaminating PBSC harvests of breast cancer (BrCa) patients. However, to assess tumor purging accurately methods may be needed that are of higher sensitivity than standard immunocytochemistry (ICC) assays. METHODS: BrCa-cell depletion, resulting from CD34(+) cell selection, was evaluated using a novel, highly sensitive assay based upon immunomagnetic enrichment with ICC detection in 36 BrCa patients undergoing highdose chemotherapy with autologous PBSC support. RESULTS: The prevalence of BrCa-cell contamination was significantly lower (P = 0.0078) in selected CD34(+) cell fractions (17/35, 49%) from apheresis collections compared with CD34(-) cell fractions (25/35, 71%). In 8/34 (24%) patients, BrCa cells were detected in CD34(-) cell fractions, but not in paired CD34(+) cell fractions. Significantly lower total numbers (P < 0.0005) of BrCa cells were enumerable in CD34(+) cell fractions compared with corresponding apheresis harvests. The median total BrCa-cell content of selected CD34(+) cell fractions with measurable contamination was 22 BrCa cells (range, 6-73 BrCa cells), compared with 3297 BrCa cells (range, 10-98 400 BrCa cells) in apheresis harvests. The median log depletion of BrCa cells achieved by positive CD34(+) cell selection in specimens with detectable contamination both before and after selection was 2.2 (range, 1.7-4.0). Total pre-selection BrCa cell number was significantly predictive (P = 0.004) of residual detectable post-selection contamination. DISCUSSION: Positive CD34(+) cell selection is an effective tumor purging strategy. The prevalence of PBSC contamination in BrCa patients is substantially higher than formerly appreciated.

Adult↗

Ethylene induces antifreeze activity in winter rye leaves.

Antifreeze activity is induced by cold temperatures in winter rye (Secale cereale) leaves. The activity arises from six antifreeze proteins that accumulate in the apoplast of winter rye leaves during cold acclimation. The individual antifreeze proteins are similar to pathogenesis-related proteins, including glucanases, chitinases, and thaumatin-like proteins. The objective of this study was to study the regulation of antifreeze activity in response to ethylene and salicyclic acid, which are known regulators of pathogenesis-related proteins induced by pathogens. Nonacclimated plants treated with salicylic acid accumulated apoplastic proteins with no antifreeze activity. In contrast, when nonacclimated plants were exposed to ethylene, both antifreeze activity and the concentration of apoplastic protein increased in rye leaves. Immunoblotting revealed that six of the seven accumulated apoplastic proteins consisted of two glucanases, two chitinases, and two thaumatin-like proteins. The ethylene-releasing agent ethephon and the ethylene precursor 1-aminocyclopropane-1-carboxylate also induced high levels of antifreeze activity at 20 degrees C, and this effect could be blocked by the ethylene inhibitor AgNO(3). When intact rye plants were exposed to 5 degrees C, endogenous ethylene production and antifreeze activity were detected within 12 and 48 h of exposure to cold, respectively. Rye plants exposed to drought produced both ethylene and antifreeze activity within 24 h. We conclude that ethylene is involved in regulating antifreeze activity in winter rye in response to cold and drought.

Antifreeze Proteins↗

Megakaryocyte-targeted synthesis of the integrin beta(3)-subunit results in the phenotypic correction of Glanzmann thrombasthenia.

Glanzmann thrombasthenia is an inherited bleeding disorder characterized by qualitative or quantitative defects of the platelet-specific integrin, alphaIIbbeta(3). As a result, alphaIIbbeta(3) cannot be activated and cannot bind to fibrinogen, leading to a loss of platelet aggregation. Thrombasthenia is clinically characterized by mucocutaneous hemorrhage with episodes of intracranial and gastrointestinal bleeding. To develop methods for gene therapy of Glanzmann thrombasthenia, a murine leukemia virus (MuLV)-derived vector, -889Pl(A2)beta(3), was transduced into peripheral blood CD34(+) cells from 2 patients with thrombasthenia with defects in the beta(3) gene. The human alphaIIb promoter was used in this vector to drive megakaryocyte-targeted expression of the wild-type beta(3) subunit. Proviral DNA and alphaIIbbeta(3) biosynthesis were detected after in vitro differentiation of transduced thrombasthenic CD34(+) cells with megakaryocyte growth and development factor. Flow cytometric analysis of transduced patient samples indicated that 19% of megakaryocyte progeny expressed alphaIIbbeta(3) on the surface at 34% of normal receptor levels. Treatment of transduced megakaryocytes with a combination of agonists including epinephrine and the thrombin receptor-activating peptide induced the alphaIIbbeta(3) complex to form an activated conformation capable of binding fibrinogen as measured by PAC-1 antibody binding. Transduced cells retracted a fibrin clot in vitro similar to megakaryocytes derived from a normal nonthrombasthenic individual. These results demonstrate ex vivo phenotypic correction of Glanzmann thrombasthenia and support the potential use of hematopoietic CD34(+) cells as targets for alphaIIb promoter-driven MuLV vectors for gene therapy of platelet disorders. (Blood. 2000;95:3645-3651)

Antigens, CD↗

Retinoic acid, midkine, and defects of secondary neurulation.

BACKGROUND: Retinoic acid (RA) is necessary for normal differentiation of the tail bud into the secondary neural tube. Excess RA, however, is teratogenic and causes neural tube defects (NTDs). The way in which RA modulates secondary neurulation is unclear but probably involves RA-regulated downstream genes such midkine (MK), which encodes a growth factor implicated in tail bud mesenchymal-neuroepithelial conversion. Our objective was to determine whether RA-deficiency would produce similar defects and if MK is involved. METHODS: Citral, a drug that blocks endogenous RA formation, as well as a neutralizing antibody, were used to block RA activity in chick embryos. Immunohistochemistry and in situ hybridization were used to localize RA and MK in the tail bud. Competitive RT-PCR was used to examine the effects of excess RA and RA deficiency due to citral on the expression of MK mRNA. RESULTS: Citral-induced NTDs displayed a morphological resemblance to those caused by excess RA. However, citral treatment did not significantly increase embryonic mortality, and RA rescue of citral-treated embryos proved unsuccessful. MK mRNA was detected in the differentiating tail bud by in situ hybridization. Competitive RT-PCR showed that excess RA decreased MK expression by 60%. Doses of citral that caused a comparable incidence of defects, however, caused only a 25% decrease. CONCLUSIONS: The results show that excess RA and RA deficiency both cause defects of secondary neurulation. While excess RA decreased MK expression, RA deficiency had minimal effects. However, whether or not MK is an intermediary in the developmental phenomena regulated physiologically or pathologically by RA remains to be elucidated.

Abnormalities, Drug-Induced↗

Effect of asthma on the quality of life among children and their caregivers in the Atlanta Empowerment Zone.

BACKGROUND AND OBJECTIVE: Asthma is the most common chronic pediatric disease and exacts a toll on the health-related quality of life of affected children and their primary caregivers. This investigation describes the relationship between the clinical severity of asthma among inner-city children and their quality of life and that of their primary adult caregivers. METHODS: Telephone interview data were collected from individual adult caregivers of 5-12-year-old children with asthma. Questions addressed the history, diagnosis, and management of the child's asthma, the child's family and social background, the family's socioeconomic status, the caregiver's knowledge and attitude about asthma, and the health-related quality of life of both the child and the caregiver. An asthma severity score was calculated from the caregiver's responses to questions about their child's wheezing frequency, nocturnal and early morning symptoms, and speaking during an asthma attack, as well as the impact of the disease on their child's physical activity and breathing during the prior 4-month period. A clinical asthma triage score was determined from information collected at the emergency department about the child's oxygen saturation, alertness, use of accessory respiratory muscles, extent of breathlessness, and peak expiratory flow. Spearman correlation coefficients were used to identify association between quality of life and disease severity, caretaker's asthma knowledge, and functional impact of asthma symptoms. RESULTS: Data from 240 of 755 eligible children were analyzed. Most children were younger than 11 years, male, black, and non-Hispanic. The children's median duration of asthma diagnosis was 86% of their life (range less than 1 to 11.3 years, median 5.0 years). Of the primary caregivers, 69% had at least completed high school, and 90% reported a total monthly household income of $1,600 or less. The maximum possible quality-of-life score and the median for caregivers were 91 and 70, respectively; for children, the same scores were 69 and 58, respectively. In addition, there was significant negative correlation of the quality-of-life scores of both the caregivers and children with the number of schooldays the children missed (r = -0.24 and r = -0.26, respectively, P < .001 for both) and the caregivers' and children's asthma severity scores (r = -0.39 and r = -0.47, respectively, P < .001 for both). The quality-of-life scores of the children and caregivers did not correlate significantly with the asthma triage scores. CONCLUSIONS: The questionnaires captured baseline quality-of-life information about this urban population and will facilitate longitudinal monitoring. The fact that the quality-of-life scores of children with asthma correlated with those of their adult caregivers, but not with their clinical triage scores, highlights the impact of asthma on families and the importance of having a long-term comprehensive management plan that is not based on exacerbations, but that includes both the children and their primary caregivers.

Asthma↗

Breast tumor contamination of peripheral blood stem cell harvests: increased sensitivity of detection using immunomagnetic enrichment.

Contaminating tumor cells in peripheral blood stem cell (PBSC) grafts infused for hematopoietic rescue after high-dose chemotherapy could potentially contribute to relapse in BrCa patients. To date the prevalence of PBSC contamination in BrCa patients, as determined by standard immuno-cytochemistry (ICC) assays, has generally been found to be relatively low. However, assay sensitivity may have an important impact on the ability to detect contamination. In this investigation a novel and highly sensitive BrCa cell assay using immunomagnetic enrichment with a panel of antiBrCa monoclonal antibodies (MAbs) and detection by ICC has been characterized. The immunomagnetic enrichment with ICC detection (IE-ICC) assay was directly compared with standard ICC in ability to detect BrCa contamination of PBSC specimens from patients with high-risk stage II/III and metastatic disease. The sensitivity of the IE-ICC assay was approximately 50-fold greater than that of standard ICC. As determined by standard ICC assay, BrCa cells were present in 1/14 patients (7%) and 2/26 (8%) specimens. In contrast, with IE-ICC assay the proportions of positive findings in patients (12/14, 86%) and specimens (19/26, 73%) were significantly higher (p = 0.001 and p < 0.0005, respectively). These preliminary findings suggest that the prevalence of PBSC contamination may be substantially higher than previously appreciated. Consequently, measures to reduce tumor contamination in the graft may have the potential to improve patient outcomes. Higher sensitivity assays such as the IE-ICC assay may play an important role in assessing the risks associated with tumor contamination and the effectiveness of tumor-purging approaches such as positive selection of CD34+ cells and in monitoring patient response to therapy.

Antibodies, Monoclonal↗

Chitinase genes responsive to cold encode antifreeze proteins in winter cereals.

Antifreeze proteins similar to two different chitinases accumulate during cold acclimation in winter rye (Secale cereale). To determine whether these cold-responsive chitinases require post-translational modification to bind to ice, cDNAs coding for two different full-length chitinases were isolated from a cDNA library produced from cold-acclimated winter rye leaves. CHT9 is a 1,193-bp clone that encodes a 31.7-kD class I chitinase and CHT46 is a 998-bp clone that codes for a 24.8-kD class II chitinase. Chitinase-antifreeze proteins purified from the plant were similar in mass to the predicted mature products of CHT9 and CHT46, thus indicating that there was little chemical modification of the amino acid sequences in planta. To confirm these results, the mature sequences of CHT9 and CHT46 were expressed in Escherichia coli and the products of both cDNAs modified the growth of ice. Transcripts of both genes accumulated late in cold acclimation in winter rye. Southern analysis of winter rye genomic DNA indicated the presence of a small gene family homologous to CHT46. In hexaploid wheat, CHT46 homologs mapped to the homeologous group 1 chromosomes and were expressed in response to cold and drought. We conclude that two novel cold-responsive genes encoding chitinases with ice-binding activity may have arisen in winter rye and other cereals through gene duplication.

Amino Acid Sequence↗

Phospholipid growth factors and corneal wound healing.

In many tissue types, wound healing involves cell division and migration over and into the wound area to cover and remodel the wound. LPA and other members of the phospholipid lipid growth factor (PLGF) family stimulate many of the activities involved in wound healing. In the rabbit cornea, we have found that keratocytes from wounded corneas have a volume-activated Cl- current activated by LPA and alkenyl-LPA. This current is minimally activated by cyclic PA and SPC, and is not activated by LPA in cells from uninjured corneas. Biochemical examination of PLGFs in aqueous humor and lacrimal fluid before and after wounding identified LPA, alkenyl-GP, PA, and lyso PS, with elevated PLGF activity after wounding. In recent experiments examining human corneal cell lines and cultured cells using RT-PCR, we found mRNA for EDG receptors 1-5, with an apparent increase in EDG-3, -4, and -5 following brief SDS application to cell lines, and EDG receptors 2-5 induction in late-passage human corneal epithelial cells. This work points to a significant role for PLGFs in the corneal wound-healing process.

Animals↗

A review of mind/body therapies in the treatment of musculoskeletal disorders with implications for the elderly.

BACKGROUND: A comprehensive, but not systematic, review of the research on complementary and alternative treatments, specifically mind/body techniques, on musculoskeletal disease was conducted at Stanford University. The goals of the review were to establish a comprehensive literature review and provide a rationale for future research carrying the theme of "successful aging." METHODS: Computerized searches were conducted using MEDLINE, PsychInfo, Stanford Library, Dissertation Abstracts, Lexus-Nexus, the Internet as well as interviews conducted with practitioners and the elderly. Mind/body practices evaluated were: social support, cognitive-behavioral therapy, meditation, the placebo effect, imagery, visualization, spiritual/energy healing, music therapy, hypnosis, yoga, tai chi, and qigong. Studies published after 1990 were the priority, but when more recent literature was scarce, other controlled studies were included. RESULTS: Mind/body techniques were found to be efficacious primarily as complementary treatments for musculoskeletal disease and related disorders. Studies provided evidence for treatment efficacy but most apparent was the need for further controlled research. CONCLUSIONS: Reviewers found a dearth of randomized controlled research conducted in the US. There is a lack of studies with which to determine appropriate dosage and understand the mechanisms by which many of the practices work. Anecdotal evidence, some controlled research, clinical observation, as well as the cost effectiveness and lack of side effects of the mind/body treatments make further investigation a high priority.

Aged↗

Functional human corneal equivalents constructed from cell lines.

Human corneal equivalents comprising the three main layers of the cornea (epithelium, stroma, and endothelium) were constructed. Each cellular layer was fabricated from immortalized human corneal cells that were screened for use on the basis of morphological, biochemical, and electrophysiological similarity to their natural counterparts. The resulting corneal equivalents mimicked human corneas in key physical and physiological functions, including morphology, biochemical marker expression, transparency, ion and fluid transport, and gene expression. Morphological and functional equivalents to human corneas that can be produced in vitro have immediate applications in toxicity and drug efficacy testing, and form the basis for future development of implantable tissues.

Animal Testing Alternatives↗

Integrin alphaIIb promoter-targeted expression of gene products in megakaryocytes derived from retrovirus-transduced human hematopoietic cells.

Megakaryocyte-specific expression of the platelet-adhesion receptor, integrin alphaIIbbeta3, is caused by the presence of regulatory elements of the alphaIIb promoter that direct high-level, selective gene transcription early in megakaryocytopoiesis. To develop methods for targeted expression of transgenes, we transduced human CD34+ peripheral blood cells with a murine leukemia virus (MuLV) vector controlled by the human integrin alphaIIb promoter (nucleotides -889 to +35). A naturally occurring cDNA encoding the Pl(A2) alloantigen form (Pro(33)) of the integrin beta3 subunit was subcloned into this construct (-889Pl(A2)beta3) and transduced into cells that endogenously synthesized Pl(A1)beta3 (Leu(33)) as a marker for detection of provirus-derived beta3. The ability of this vector to target expression of Pl(A2)beta3 to megakaryocytes was first examined in cell lines. Immunoblot analysis with human anti-Pl(A2) alloserum detected synthesis of Pl(A2)beta3 in transduced promegakaryocytic cells; however, Pl(A2)beta3 protein was not detected in transduced epithelial cells. Human hematopoietic CD34+ cells were transduced with -889Pl(A2)beta3 virions and induced to differentiate with megakaryocyte growth and development factor. A hybrid alphaIIbbeta3 complex was formed in progeny megakaryocytes where provirus-derived Pl(A2)beta3 was detected associated with endogenous alphaIIb subunit. Another alphaIIb promoter-driven MuLV vector (-889nlacZ) encoding Escherichia coli beta-galactosidase was used to demonstrate that transgene expression was selectively targeted to the megakaryocyte progeny of transduced CD34+ cells. These studies demonstrate the feasibility of using alphaIIb promoter-driven MuLV vectors for gene transfer of hematopoietic CD34+ cells to target transgene expression in developing megakaryocytes and platelets and indicate potential applications toward human gene therapy for platelet disorders.

Antigens, CD34↗

Antifreeze proteins in winter rye leaves form oligomeric complexes

Antifreeze proteins (AFPs) similar to three pathogenesis-related proteins, a glucanase-like protein (GLP), a chitinase-like protein (CLP), and a thaumatin-like protein (TLP), accumulate during cold acclimation in winter rye (Secale cereale) leaves, where they are thought to modify the growth of intercellular ice during freezing. The objective of this study was to characterize the rye AFPs in their native forms, and our results show that these proteins form oligomeric complexes in vivo. Nine proteins were separated by native-polyacrylamide gel electrophoresis from apoplastic extracts of cold-acclimated winter rye leaves. Seven of these proteins exhibited multiple polypeptides when denatured and separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. After isolation of the individual proteins, six were shown by immunoblotting to contain various combinations of GLP, CLP, and TLP in addition to other unidentified proteins. Antisera produced against individual cold-induced winter rye GLP, CLP, and TLP all dramatically inhibited glucanase activity in apoplastic extracts from cold-acclimated winter rye leaves, and each antiserum precipitated all three proteins. These results indicate that each of the polypeptides may be exposed on the surface of the protein complexes. By forming oligomeric complexes, AFPs may form larger surfaces to interact with ice, or they may simply increase the mass of the protein bound to ice. In either case, the complexes of AFPs may inhibit ice growth and recrystallization more effectively than the individual polypeptides.

Journal Article↗

Snow-mold-induced apoplastic proteins in winter rye leaves lack antifreeze activity

During cold acclimation, winter rye (Secale cereale L.) plants secrete antifreeze proteins that are similar to pathogenesis-related (PR) proteins. In this experiment, the secretion of PR proteins was induced at warm temperatures by infection with pink snow mold (Microdochium nivale), a pathogen of overwintering cereals. A comparison of cold-induced and pathogen-induced proteins showed that PR proteins accumulated in the leaf apoplast to a greater level in response to cold. The PR proteins induced by cold and by snow mold were similar when separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and examined by immunoblotting. Both groups of PR proteins contained glucanase-like, chitinase-like, and thaumatin-like proteins, and both groups exhibited similar levels of glucanase and chitinase activities. However, only the PR proteins induced by cold exhibited antifreeze activity. Our findings suggest that the cold-induced PR proteins may be isoforms that function as antifreeze proteins to modify the growth of ice during freezing while also providing resistance to the growth of low-temperature pathogens in advance of infection. Both functions of the cold-induced PR proteins may improve the survival of overwintering cereals.

Journal Article↗

Evaluation of current techniques of corneal epithelial removal in hyperopic photorefractive keratectomy.

PURPOSE: To determine the efficacy of 3 current methods used to remove corneal epithelium prior to photorefractive correction of hyperopia and to compare clinical data in patients who had rotary brush or blunt scrape epithelial removal in the treatment of hyperopic photorefractive keratectomy (PRK). SETTING: University of Ottawa Eye Institute, Ottawa General Hospital, Ottawa, Ontario, Canada. METHODS: The epithelium from human eye-bank eyes was removed using a Paton spatula, 15% alcohol, and the Amoils rotating plastic brush. The effects were examined by scanning and transmission electron microscopy. Twelve month postoperative data were obtained on 25 eyes with refractions of +1.00 to +4.00 diopters (D) that had been treated for hyperopia with the VISX Star excimer laser, using blunt scrape or the rotary brush to remove the corneal epithelium. RESULTS: All 3 methods effectively removed corneal epithelium. The Paton spatula, however, left small nicks in Bowman's layer. Both the rotating brush and alcohol debridement left Bowman's layer intact. Alcohol treatment required follow-up epithelial debris removal, while brushing left minimal amounts of debris. There was a strong trend toward rapid epithelial healing in the brushed corneas compared with the scraped ones, but this was not statistically significant. Clinically, at 12 months postoperatively, brushed corneas showed a trend toward more superior outcomes than scraped corneas in actual refractive outcome, uncorrected visual acuity (UCVA), lines of UCVA gained, and predictability of the desired outcomes. However, only the outcome in UCVA of 20/40 or better and the decreased incidence of haze in the brushed corneas over scraped ones were statistically significant. CONCLUSIONS: Both alcohol and the rotating brush provide a quick, effective means of removing the corneal epithelium with minimal risk of damage to Bowman's layer. In our experience, the brush technique was as effective as and possibly superior to the blunt scrape for epithelial removal in hyperopic PRK.

Adult↗

Risk of congenital inguinal hernia in siblings: a record linkage study.

Using data from the Oxford Record Linkage Study (ORLS), we conducted a case-control study to estimate the sex-specific risks of inguinal hernia in siblings of children with this condition. There were 1921 male and 347 female cases born during 1970-86 who were operated on for inguinal hernia at ages 0-5 years during 1970-87, with 12,886 male and 2534 female control subjects. The relative risk of inguinal hernia was 5.8 [95% confidence interval 4.0-8.4] for brothers of male cases and 4.3 [2.1-8.7] for brothers of female cases (both relative to brothers of control subjects). The relative risk was 3.7 [1.8-7.9] for sisters of male cases and 17.8 [6.9-46.3] for sisters of female cases (both relative to sisters of control subjects). The pattern of sex-dependent risks, particularly the large risk for sisters of female cases, suggests a multifactorial threshold model for the disease. Girls have much lower rates of inguinal hernia than boys, and if these rates are low because of a low susceptibility to disease due to the absence of a sex-related risk factor, then those girls who develop disease might have a potentially large contribution to susceptibility from genetic or intrauterine risk factors unrelated to sex.

Case-Control Studies↗