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Biomedical subjects

B A Morris

Publications and source records attributed to B A Morris.

At least 19 recordsLinked to original sources
PubMed2001

Parthenocarpic apple fruit production conferred by transposon insertion mutations in a MADS-box transcription factor.

Fruit development in higher plants normally requires pollination and fertilization to stimulate cell division of specific floral tissues. In some cases, parthenocarpic fruit development proceeds without either pollination or fertilization. Parthenocarpic fruit without seed has higher commercial value than seeded fruit. Several apple (Malus domestica) mutants (Rae Ime, Spencer Seedless and Wellington Bloomless) are known to produce only apetalous flowers that readily go on to develop into parthenocarpic fruit. Through genetics, a single recessive gene has been identified to control this trait in apple. Flower phenotypes of these apple mutants are strikingly similar to those of the Arabidopsis mutant pistillata (pi), which produces flowers where petals are transformed to sepals and stamens to carpels. In this study, we have cloned the apple PI homolog (MdPI) that shows 64% amino acid sequence identity and closely conserved intron positions and mRNA expression patterns to the Arabidopsis PI. We have identified that in the apetalous mutants MdPI has been mutated by a retrotransposon insertion in intron 4 in the case of Rae Ime and in intron 6 in the case of Spencer Seedless and Wellington Bloomless. The insertion apparently abolishes the normal expression of the MdPI gene. We conclude that the loss of function mutation in the MdPI MADS-box transcription factor confers parthenocarpic fruit development in these apple varieties and demonstrates another function for the MADS- box gene family. The knowledge generated here could be used to produce parthenocarpic fruit cultivars through genetic engineering.

Amino Acid Sequence↗
PubMed2001

In vivo changes after mechanical injury.

Chondrocytes undergo apoptosis in response to mechanical injury in vitro. The current clinical study correlates arthroscopic and magnetic resonance imaging results with biopsy specimens of cartilage from patients with knee injury. Twenty patients were evaluated at a mean 2.7 months after acute knee injury. The mean age of the patients was 32 years and the mean weight was 83 kg. Cartilage lesions were graded separately on magnetic resonance images and arthroscopy in a blinded manner. During arthroscopy, a 1.8 mm diameter biopsy specimen was obtained from the edge of cartilage lesion. The biopsy specimen underwent histologic examination by safranin O staining and detection of chondrocyte apoptosis by the presence of deoxyribonucleic acid fragmentation. There was a positive correlation in 50% (10 of 20) when the presence or absence of cartilage lesions by magnetic resonance imaging was correlated with arthroscopy. All cases of partial thickness or full-thickness cartilage loss that were seen by arthroscopy also were detected by magnetic resonance images. Apoptotic cells were significantly more numerous in biopsy specimens from lesions compared with control biopsy specimens. The findings of reduced cell viability attributable to apoptosis may have profound implications for cartilage repair. This opens potential therapeutic avenues for the treatment of posttraumatic cartilage lesions through apoptosis prevention.

Adult↗
PubMed2000

MDH1: an apple homeobox gene belonging to the BEL1 family.

Differential display was used to isolate genes differentially expressed early in fruit development of apple (Malus domestica Borkh.). This approach resulted in the isolation of MDH1, a homeobox gene with a homeodomain similar to that of BELL1 (BEL1), which is involved in regulation of ovule development in Arabidopsis. However, outside the homeodomain MDH1 is quite different from BEL1. In apple, MDH1 mRNA was predominantly found in flowers, expanding leaves and expanding fruit. In pre-anthesis flowers, in situ hybridization showed that MDH1 mRNA accumulated in ovules. To further investigate the function of this new homeobox gene, MDH1 was transformed into Arabidopsis thaliana under the control of the cauliflower mosaic virus 35S promoter. The transgenic Arabidopsis plants showed dwarfing, reduced fertility and changes in carpel and fruit (silique) shape. The size and shape of the cells in the transgenic fruit was irregular. Both the transgenic phenotypes in Arabidopsis and the expression pattern of this gene in apple are consistent with the idea that MDH1 is likely to play an important role in control of plant fertility.

Amino Acid Sequence↗
PubMed2000

Veterinary sources of nonrodent monoclonal antibodies: interspecific and intraspecific hybridomas.

The generation of monoclonal antibodies from species other than rats and mice has developed slowly over the last 20 years. The advent of antibody engineering and realization of the advantages of nonmurine antibodies, in terms of their superior affinities and specificities, and their potential as components of human and veterinary therapeutics has increased their relevance recently. There have been significant advances in the development of myeloma and heteromyeloma fusion partners. This is an opportune moment to consolidate experiences of MAb production across the range of species of veterinary interest and place it into context with other developments in the field of monoclonal antibodies. The background to the development of antibodies from species other than the mouse is discussed. The species and antigens used to date are reviewed, as are the methods and results reported. A suggested protocol is provided for first attempts to exploit the huge potential of this aspect of hybridoma technology and suggestions are made for its further expansion.

Animals↗
PubMed2000

Isolation of three distinct CycD3 genes expressed during fruit development in tomato.

Tomato (Lycopersicon esculentum Mill.) is an important fruit crop world-wide and a model for studying fruit development. As determined using flow cytometry, fruit growth was characterized by high cell division activity in tomato during the first week after anthesis and followed by endoreduplications (DNA replication without cell divisions). D-type cyclins are considered to be important parts of the signal transduction for stimulation of DNA replication and cell division. To study the function of D cyclins in fruit development, full-length cDNA clones for three D cyclin genes were isolated from young tomato fruit. They were classified as D3 cyclins by sequence similarities and a phylogenetic analysis and named as LeCycD3;1, LeCycD3;2 and LeCycD3;3. The deduced amino acid sequences for LeCycD3;1-3 contained a retinoblastoma-binding motif and a PEST-destruction motif. Pollination and fertilization were followed by a high increase in the transcript levels of LeCycD3;1-3 in young fruit. Using in situ hybridization, high expression of LeCycD3;3 was detected in the vascular tissue of young fruit suggesting a role in vascular development. The D3 cyclins are probably involved in transducing the signals leading to fruit growth by cell divisions. Distinct differences were detected in their temporal and spatial expression patterns suggesting that they play different roles in fruit development as well as in the development of other plant organs.

Amino Acid Sequence↗
PubMed1999

Selectable marker-free transgenic plants without sexual crossing: transient expression of cre recombinase and use of a conditional lethal dominant gene.

Transgenic tobacco plants were produced that contained single-copy pART54 T-DNA, with a 35S-uidA gene linked to loxP-flanked kanamycin resistance (nptII) and cytosine deaminase (codA) genes. Retransformation of these plants with pCre1 (containing 35S transcribed cre recombinase and hygromycin (hpt) resistance genes) resulted in excision of the loxP-flanked genes from the genome. Phenotypes of progeny from selfed-retransformed plants confirmed nptII and codA excision and integration of the cre-linked hpt gene. To avoid integration of the hpt gene, and thereby generate plants totally free of marker genes, we attempted to transiently express the cre recombinase. Agrobacterium tumefaciens (pCre1) was cocultivated with leaf discs of two pART54-transformed lines and shoots were regenerated in the absence of hygromycin selection. Nineteen of 773 (0.25%) shoots showed tolerance to 5-fluorocytosine (5-fc) which is converted to the toxic 5-fluorouracil by cytosine deaminase. 5-fc tolerance in six shoots was found to be due to excision of the loxP-flanked region of the pART54 T-DNA. In four of these shoots excision could be attributed to cre expression from integrated pCre1 T-DNA, whereas in two shoots excision appeared to be a consequence of transient cre expression from pCre1 T-DNA molecules which had been transferred to the plant cells but not integrated into the genome. The absence of selectable marker genes was confirmed by the phenotype of the T1 progeny. Therefore, through transient cre expression, marker-free transgenic plants were produced without sexual crossing. This approach could be applicable to the elimination of marker genes from transgenic crops which must be vegetatively propagated to maintain their elite genotype.

Agrobacterium tumefaciens↗
PubMed1999

Molecular-based approach to the differentiation of mealybug (Hemiptera: Pseudococcidae) species.

The rDNA internal transcribed spacer (ITS) region of 4 mealybug species, Pseudococcus viburni (Signoret), P. longispinus (Targiono-Tozzetti), P. calceolariae (Maskell), and P. similans (Lidgett), was isolated by polymerase chain reaction (PCR) amplification, cloned, and sequenced. In this region of the genome there were numerous differences, including nucleotide substitutions, insertions, or deletions between P. viburni, P. longispinus, and P. calceolariae, whereas P. calceolariae and P. similans were very similar. Based on sequence differences between the ITS regions, we designed PCR primers that were able to differentiate the 4 mealybug species and that correlated with morphological differences found between adult females of these species. The PCR amplification by using the species-specific primers enabled the differentiation of not only adult females but also eggs, juveniles, and adult males, which was not previously possible by using conventional identification methods.

Animals↗
PubMed1999

Blood loss and transfusion rate in noncemented and cemented/hybrid total hip arthroplasty. Is there a difference? A comparison of 25 matched pairs.

A common assumption among orthopedic surgeons is that cemented/hybrid total hip arthroplasty (THA) results in lower transfusion requirements than noncemented THA. The hypothesized mechanism to account for transfusion differences is that cement application, after polymerization, decreases perioperative blood loss. To evaluate this theory, a retrospective matched-pair study was performed to quantify perioperative, intraoperative, postoperative blood loss, and transfusion requirements among patients undergoing cemented/hybrid and noncemented THA. Twenty-five THA procedures were either cemented or hybrid and 25 were noncemented. Patients were matched with respect to age, gender, weight, and diagnosis. Six patients in the noncemented group and 10 in the cemented/hybrid group received autologous blood in the Post Anesthesia Care Unit. Among this subgroup, those in the cemented/hybrid group received a significantly greater volume of transfused blood (519.20 mL, versus 291.67 mL in the noncemented group, P < .017). After stratifying patients by gender, additional analysis revealed a greater total blood loss in the male population than in females (1848 mL versus 1464 mL, P < .004). Males also had a greater drain volume (548 mL versus 414 mL, P < .02). The female population utilizing hormone replacement therapy (HRT) was found to have a lesser blood loss (810 mL versus 1209 mL, P < .0107) and received a smaller amount of transfused blood (1164 mL versus 1377 mL) than those who were not on HRT. Other significant findings included a shorter length of stay in the cemented/hybrid group (6.85 versus 7.56 days, P < .012). Based on this matched-pair retrospective analysis of blood requirements, there is no indication that cemented/hybrid and noncemented THA procedures result in different blood requirements. However, differences were found in several areas when the population was stratified by gender. The information obtained from this study is important in its ability to solidify a foundation from which blood management decisions can be made.

Aged↗
PubMed1998

Major changes in chromatin condensation suggest the presence of an apoptotic pathway in plant cells.

A large decrease in fluorescence intensity of propidium iodide (PI)-stained nuclei is observed during senescence of plant cells. The phenomenon reflects a decrease in accessibility of DNA to this fluorochrome and is a consequence of chromatin condensation. This decrease is substantially greater than usually found in animal nuclei whose chromatin undergoes condensation, e.g., during differentiation or quiescence. Chromatin condensation was confirmed by analyses of (i) DNA accessibility to DNase I, (ii) histone disassociation induced by HCl, (iii) saturation of binding sites by the PI fluorochrome (iv), and (v) visual inspection by fluorescence and confocal microscopy. The extent of changes revealed by these assays was used to map progressive changes in chromatin condensation which allowed us to identify different stages in an apoptosis-like pathway in plants. The initial step of chromatin condensation which occurred prior to endonucleolytic DNA degradation was detected by fluorescence and confocal microscopy and confirmed by a variety of assays employing flow cytometry. The initial chromatin condensation appears to be a reversible step in the early stage of apoptosis. The loss of reversibility of chromatin condensation observed subsequently may be a critical point in the cascade of apoptotic events, leading to further irreversible changes during apoptosis in plants.

Acids↗
PubMed1997

Hemodilution with other blood reinfusion techniques in total hip arthroplasty.

Acute normovolemic hemodilution has been reported to result in blood savings varying from 18% to 90%. Very few of these are randomized prospective studies. This study attempts to determine the blood transfusion savings if acute normovolemic hemodilution is used in combination with autologous predonated blood and cell saver. Thirty-three patients undergoing total hip arthroplasty were assigned randomly to one of two groups (control, n = 16; hemodilution, n = 17). Patients in both groups entered an autologous predonation program if cleared medically and were placed on Cell Saver intraoperatively and in the postanesthesia care unit. In addition, the hemodilution group underwent acute normovolemic hemodilution preoperatively. Only 41% of the patients in the hemodilution group required any autologous blood transfusion as compared with 75% of the control group. In addition, the hemodilution group required a mean lower quantity of autologous blood transfusion (41% of the estimated blood loss) as compared with the control group (71%). The net anesthesia time increased by an average of 11.4 minutes in the hemodilution group. Acute normovolemic hemodilution is a safe procedure even in an older patient population. Hemodilution resulted in fewer patients needing autologous predonated blood transfusions. The major benefit of hemodilution was seen when predonation was not possible.

Adolescent↗
PubMed1997

Emergency arrhythmia management: an assessment of learning needs.

For physicians working in emergency departments, optimum management of patients with arrhythmias is an important skill. To assess the learning needs of Canadian emergency physicians with respect to arrhythmias, the members of the Canadian Association of Emergency Physicians (CAEP) were surveyed. The survey assessed perceived learning needs and included 11 scenarios assessing physician knowledge. Of 883 surveys distributed, 278 were returned, a response rate of 31.5%. The topic areas ranked most highly by respondents in terms of perceived learning needs were management of ventricular arrhythmias (especially electrical strom), and clinical use of oral and intravenous antiarrhythmic drugs, particularly the clinical use of intravenous amiodarone. The assessment of knowledge showed that the respondents managed most arrhythmias in accordance with published guidelines, although the management of some wide complex tachyarrhythmias was not optimal. These results will be used to guide an ongoing program of continuing medical education.

Anti-Arrhythmia Agents↗
PubMed1996

The effect of preoperative exercise on total knee replacement outcomes.

This study compared the effects of preoperative physical therapy of general cardiovascular conditioning exercises with the routine procedure of no preoperative physical therapy on patients undergoing primary total knee replacement. Thirty patients were randomly assigned to 1 of 3 groups. Group 1 was the control group. Group 2 participated in a physical therapy program designed to strengthen the upper and lower limbs and improve knee range of motion. Group 3 participated in a cardiovascular conditioning program, consisting of arm ergometry, cycle ergometry, aquatic exercises, and aerobic activity. All patients were evaluated preoperatively and postoperatively using the Hospital for Special Surgery Knee Rating, the Arthritis Impact Measurement Scale, and the Quality of Well Being instrument. Both experimental groups tolerated their respective exercise protocols extremely well. All 3 groups showed significant improvement postoperatively as measured by the Hospital for Special Surgery Knee Rating, the Arthritis Impact Measurement Scale and the Quality of Well Being measurement scales. However, neither type of preoperative exercise added to the degree of improvement after surgery at any of the postoperative evaluations.

Aged↗
PubMed1996

Osteonecrosis of the femoral head in patients with inflammatory arthritis or asthma receiving corticosteroid therapy.

The utilization of corticosteroids in the management of acute and chronic inflammatory processes, such as asthma or inflammatory arthritis, has been implicated in the adverse effects of multiple organ systems. One potential area of these negative consequences in the use of corticosteroids is the development of osteonecrosis of the femoral head. A direct time/dosage relationship for treatment with corticosteroids of patients with an established diagnosis of asthma or inflammatory arthritis and femoral osteonecrosis is unknown. A prospective study was undertaken to evaluate the use of corticosteroids and the incidence of osteonecrosis of the femoral head and potentially establish a time/dosage relationship in this patient population. No direct relationship between corticosteroid dosage and the development of femoral head osteonecrosis in 1420 hip-years was demonstrated at 10-year follow up.

Adrenal Cortex Hormones↗
PubMed1995

Cloning and sequencing of a gene encoding the 69-kDa extracellular chitinase of Janthinobacterium lividum.

Janthinobacterium lividum secretes a major 56-kDa chitinase and a minor 69-kDa chitinase. A chitinase gene was defined on a 3-kb fragment of clone pRKT10, by virtue of fluorescent colonies in the presence of 4-methylumbelliferyl-beta-D-N,N',N"-chitotrioside. Nucleotide sequencing revealed an 1998-bp open reading frame with the potential to encode a 69,716-Da protein with amino acid sequences similar to those in other chitinases, suggesting it encodes the minor chitinase (Chi69). Chitinase activity of Escherichia coli (pRKT10) lysates was detected mainly in the periplasmic fraction and immunoblotting detected a 70-kDa protein in this fraction. Chi69 has an N-terminal secretory leader peptide preceding two probable chitin-binding domains and a catalytic domain. These functional domains are separated by linker regions of proline-threonine repeats. Amino acid sequencing of cyanogen bromide cleavage-derived peptides from the major 56-kDa chitinase suggested that Chi69 may be a precursor of Chi56. In addition, an N-terminally truncated version of Chi69 retained chitinase activity as expected if in vivo processing of Chi69 generates Chi56.

Amino Acid Sequence↗
PubMed1995

Patient-controlled analgesia compared with intramuscular injection of analgesics for the management of pain after an orthopaedic procedure.

Patients who were scheduled for an elective joint replacement or spinal procedure were randomly assigned prospectively to one of two groups for the management of postoperative pain: ninety-one patients (Group I) controlled the administration of a narcotic analgesic themselves and ninety-three patients (Group II) received intramuscular injections of a narcotic analgesic, as needed. The patients who controlled the analgesic used a smaller amount of the analgesic on the first postoperative day, but the over-all amount was not significantly different between the two groups. The group that received intramuscular injections reported less pain overall, according to one of three pain-assessment scales, and had more relief of pain over-all and on the first postoperative day, according to another scale. The patients who had had a total joint replacement and who controlled the analgesia walked farther on the first postoperative day than those who received intramuscular injections. There were no significant differences between the two groups with regard to the rate of complications, the arterial oxygen saturation levels during the first twenty-four hours after the operation, or the length of stay in the hospital. The nursing staff preferred the patient-administered method of analgesia, as it necessitated equal or less nursing time to assemble, initiate, and maintain than traditional intramuscular injections. The average cost per patient was $58.58 for the patient-administered analgesia and $22.45 for the intramuscular injections.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗