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Biomedical subjects

R Birch

Publications and source records attributed to R Birch.

At least 55 records · Page 3Linked to original sources
PubMed2001

Ribozyme genes protecting transgenic melon plants against potyviruses.

Potyviruses are the most important viral pathogens of crops worldwide. Under a contract with Gene Shears Pty Limited, we are using ribozyme genes to protect melon plants against two potyviruses: WMV2 and ZYMV. Different polyribozyme genes were designed, built and introduced into melons plants. Transgenic melon plants containing a resistance gene were obtained and their progeny was challenged by the appropriate virus. Most of the genes tested conferred some degree of resistance to the viruses in glasshouse trials. Melon plants from one family containing one gene directed against WMV2 were also field-trialed on small plots under natural infection pressure and were found immune to WMV2. Field trial is in progress for plants containing genes against ZYMV. Some of the ribozyme genes used in the plants were also assayed in a transient expression system in tobacco cells. This enabled us to study the sequence discrimination capacity of the ribozyme in the case of one ribozyme target site. We found that a mutated target GUG (non cleavable) was less susceptible to inhibition by the ribozyme gene than the corresponding wild type target GUA (cleavable). Work is now in progress to incorporate multiple resistance genes in melon plants, in constructs designed in compliance with the evolving European regulations concerning transgenic plants. The use of ribozyme genes to protect plants against viruses provides an alternative to the technologies currently used for protecting crops against viruses, based on the concept of Pathogen Derived Resistance (see for example 14). In the light of concerns expressed by some plant virologists (13) about the use of viral genes in transgenic plants, it may be that ribozyme genes will find many uses in this area of agricultural biotechnology.

Agriculture↗
PubMed2001

Injuries to the brachial plexus: controversies and possibilities.

The complete supraclavicular traction lesion of the brachial plexus is perhaps the most shattering of all injuries of the peripheral nerves. Its highest incidence is in young persons, and the results of treatment, although better than they were formerly, are still poor.

Brachial Plexus↗
PubMed2000

P2X3 receptor in injured human sensory neurons.

The ATP-gated cation channel P2X3 is expressed selectively by rat sensory neurones, and may play a role in nociception by binding ATP released from damaged or inflamed tissues. However, the distribution of this channel in human sensory neurons is not known. Using a specific antibody, we have demonstrated intense P2X3 immunoreactivity within a subset (60%) of small/medium diameter sensory neurones and fine nerve fibres in intact post-mortem human dorsal root ganglia (DRG). Co-localization studies showed < 15% overlap with the trkA immunostaining in DRG, indicating that P2X3 was expressed predominantly in sensory neurons that are also isolectin B4 positive. There was a significant decrease in numbers of P2X3-like immunoreactive neurons in human DRG after central axotomy (to 36%), similar to the decrease in rat DRG after peripheral axotomy. However, Western blotting demonstrated a specific 66 kDa band in human DRG and peripheral organs, including intestine, where histochemistry showed P2X3 immunoreactivity in myenteric plexus neurons. Thus P2X3 antagonists may be analgesic, but are unlikely to have a selective effect on pain in humans.

Adult↗
PubMed2000

SNS/PN3 and SNS2/NaN sodium channel-like immunoreactivity in human adult and neonate injured sensory nerves.

Two tetrodotoxin-resistant voltage-gated sodium channels, SNS/PN3 and SNS2/NaN, have been described recently in small-diameter sensory neurones of the rat, and play a key role in neuropathic pain. Using region-specific antibodies raised against different peptide sequences of their alpha subunits, we show by Western blot evidence for the presence of these channels in human nerves and sensory ganglia. The expected fully mature 260 kDa component of SNS/PN3 was noted in all injured nerve tissues obtained from adults; however, for SNS2/NaN, smaller bands were found, most likely arising from protein degradation. There was increased intensity of the SNS/PN3 260 kDa band in nerves proximal to the site of injury, whereas it was decreased distally, suggesting accumulation at sites of injury; all adult patients had a positive Tinel's sign at the site of nerve injury, indicating mechanical hypersensitivity. Injured nerves from human neonates showed similar results for both channels, but neonate neuromas lacked the SNS2/NaN 180 kDa molecular form, which was strongly present in adult neuromas. The distribution of SNS/PN3 and SNS2/NaN sodium channels in injured human nerves indicates that they represent targets for novel analgesics, and could account for some differences in the development of neuropathic pain in infants.

Adolescent↗
PubMed2000

Immunolocalization of SNS/PN3 and NaN/SNS2 sodium channels in human pain states.

The tetrodotoxin-resistant (TTX-R) voltage-gated sodium channel SNS/PN3 and the newly discovered NaN/SNS2 are expressed in sensory neurones, particularly in nociceptors. Using specific antibodies, we have studied, for the first time in humans, the presence of SNS/PN3 and NaN/SNS2 in peripheral nerves, including tissues from patients with chronic neurogenic pain. In brachial plexus injury patients, there was an acute decrease of SNS/PN3- and NaN/SNS2-like immunoreactivity in sensory cell bodies of cervical dorsal root ganglia (DRG) whose central axons had been avulsed from spinal cord, with gradual return of the immunoreactivity to control levels over months. In contrast, there was increased intensity of immunoreactivity to both channels in some peripheral nerve fibers just proximal to the site of injury in brachial plexus trunks, and in neuromas. These findings suggest that the expression of these sodium channels in neuronal cell bodies is reduced after spinal cord root avulsion injury in man, but that pre-synthesized channel proteins may undergo translocation with accumulation at sites of nerve injury, as in animal models of peripheral axotomy. The latter may contribute to positive symptoms, as our patients all showed a positive Tinel's sign. Nerve terminals in distal limb neuromas and skin from patients with chronic local hyperalgesia and allodynia all showed marked increases of SNS/PN3-immunoreactive fibers, but little or no NaN/SNS2-immunoreactivity, suggesting that the former may be related to the persistent hypersensitive state. Axonal immunoreactivity to both channels was similar to control nerves in sural nerve biopsies in a selection of neuropathies, irrespective of nerve inflammation, demyelination or spontaneous pain, including a patient with congenital insensitivity to pain. Our studies suggest that the best target for SNS/PN3 blocking agents is likely to be chronic local hypersensitivity.

Adult↗
PubMed2000

Intact myelinated fibres in biopsies of ventral spinal roots after preganglionic traction injury to the brachial plexus. A proof that Sherrington's 'wrong way afferents' exist in man?

Bell-Magendie's law of separation of spinal function states that afferent and efferent fibres join the spinal cord separately in ventral and dorsal spinal nerve roots. For over 100 years there have been reports that challenge the exclusiveness of this law in mammals; very few studies have referred to man. We conducted a prospective morphological study in patients with preganglionic traction injuries of the brachial plexus to address this question. Avulsed ventral and dorsal roots were examined after variable intervals from the injury for histological and ultrastructural evidence for myelinated afferent fibres entering the cord via the ventral roots. Intact myelinated fibres were found in all ventral root specimens, but the majority of fibres in later biopsies are regenerative. A small number of fibres could be demonstrated that are likely to be 'wrong way ventral afferents'. Their number is falsely low due to wallerian degeneration of dorsal and ventral afferents following the mechanical and ischaemic effects of traction injury. Our findings are the first morphological evidence in human material that Bell-Magendie's law might not entirely be correct and they underline the difficulties in comparing traumatic with experimental rhizotomy.

Adult↗
PubMed2000

HSE performance tests for dosimetry services.

In the United Kingdom a dosimetry service that measures and assesses whole-body or part-body doses arising from external radiation must successfully complete a performance test. Results of the performance tests for routine whole-body, routine extremity/skin and special accident dosimetry, carried out over the past six years by the AEA Technology Calibration Service at Winfrith, and DRaStaC, the AWE Calibration Service at Aldermaston, are presented. The test involves irradiating groups of dosemeters to known doses of gamma radiation and determining the bias and relative standard deviations for each dose group. The results are compared with the pass criteria specified by the UK Health and Safety Executive. For routine whole-body dosimetry, both the film badge and thermoluminescent dosemeter (TLD) perform adequately for irradiations between 0.6 and 30 mSv. For higher doses up to 250 mSv, where the slow emulsion of the film is used, the film badge shows poorer performance with a tendency to overestimate the dose. For routine extremity/skin dosimetry there is a wider spread of relative standard deviation results than is seen for routine whole-body dosimetry. This is to be expected since the results will include dosemeters that are based on 'disposable' TLDs and ones based on lithium fluoride powder in sachets. For special accident dosimetry the dosemeters are tested between 0.26 and 6 Gy. For the highest dose group the film badge invariably underestimates the true dose, whereas the TLD has a tendency to overestimate it.

Information Services↗
PubMed2000

Randomized trial of filgrastim, sargramostim, or sequential sargramostim and filgrastim after myelosuppressive chemotherapy for the harvesting of peripheral-blood stem cells.

PURPOSE: The purpose of this study was to compare the effects of filgrastim, sargramostim, or sequential sargramostim and filgrastim on CD34(+) cell yields and morbidity after myelosuppressive mobilization chemotherapy (MC). PATIENTS AND METHODS: One hundred fifty-six patients were randomized to receive filgrastim (n = 51), sargramostim (n = 52), or sargramostim for 5 days followed by filgrastim (n = 53) after MC with either cyclophosphamide and etoposide (n = 75) or paclitaxel and cyclophosphamide (n = 81). RESULTS: Compared with those who received sargramostim, patients who received filgrastim had faster recovery of an absolute neutrophil count of 0.5 x 10(9)/L or greater (a median of 11 v 14 days; P =. 0001), with fewer patients requiring RBC transfusions (P =.008), fewer patients with fever (18% v 52%; P = 0.001), fewer hospital admissions (20% v 42%; P =.013), and less intravenous antibiotic therapy (24% v 69%; P =.001). Patients who received filgrastim yielded more CD34(+) cells (median, 7.1 v 2.0 x 10(6)/kg/apheresis; P =.0001), and a higher fraction achieved 2.5 x 10(6) (94% v 78%; P =.021) and 5 x 10(6) (88% v 53%; P =.001) or more CD34(+) cells/kg with fewer aphereses (median, 2 v 3; P =.002) and fewer days of growth-factor treatment (median, 12 v 14; P =.0001). There were no major differences in outcomes between the filgrastim alone and the sequential regimens. After high-dose chemotherapy, patients who had peripheral-blood stem cells (PBSCs) mobilized with filgrastim or the sequential regimen received higher numbers of CD34(+) cells and had faster platelet recovery (P =.015), with fewer patients (P =.014) receiving fewer platelet transfusions (P =.001) than patients receiving sargramostim-mobilized PBSCs. CONCLUSION: It was concluded that filgrastim alone or sequential sargramostim and filgrastim were superior to sargramostim alone for the mobilization of CD34(+) cells and reduction of toxicities after MC.

Adult↗
PubMed2000

Peripheral nerve repairs and their results in children.

It seems that lesions of nerves in children account for 10% to 15% of the total cases seen in this, as in other, specialist units. The prognosis for recovery after repair is defined by the severity of the original injury. The authors' worst results were seen in complete lesions of the supraclavicular brachial plexus and in the untidy wounds of war, in which penetrating missiles destroyed the proximal femur and the adjacent nerves. The outcome for injuries to the lumbosacral plexus, from fractures of the pelvis or from penetrating missile injury, are as bad. The most significant variable in determining prognosis is delay. Evidently, children are at least as vulnerable to the harmfulness of this as are adults. Skillful primary repair, however, is often followed by recovery to near normal levels, even in complex cases. Adequate follow-up is essential to detect and treat progressive deformity, especially at the ankle and foot.

Child↗
PubMed1999

High-dose chemotherapy with peripheral blood stem cell support for stage IIIB inflammatory carcinoma of the breast.

The purpose of this study was to determine outcomes for 56 patients with inflammatory breast cancer (IBC) receiving high-dose chemotherapy (HDC) with cyclophosphamide, thiotepa and carboplatin (CTCb) with peripheral blood stem cell (PBSC) support. All patients received the same total amount of chemotherapy but there were differences in the sequence of therapy: 15 received induction chemotherapy, chemotherapy mobilization of PBSC and CTCb after surgery (adjuvant group) while 41 received induction chemotherapy with (n = 17) or without (n = 24) chemotherapy for mobilization of PBSC prior to surgery and CTCb after surgery (neoadjuvant group). Median time from diagnosis to HDC was 5.5 months (range 3.5-12.5). Fifty-one patients (91%) required admission to the hospital following HDC for a median of 11 days (range 5-25). There were two (4%) infectious deaths after HDC. Twenty-four patients (43%) have relapsed at a median of 18 months (range 8-50) from diagnosis resulting in death in 34%. The probabilities of overall (OS) and event-free survival (EFS) at 3 years for all 56 patients were 0.72 and 0.53, respectively, with a median follow-up of 44 months (range 15-76) from diagnosis. There were no differences in OS, EFS or patterns of relapse between patients in the adjuvant or neoadjuvant groups. These sequences of combined modality therapy incorporating HDC are comparable or superior to other intensive approaches for the treatment of IBC. Further improvements will be necessary to decrease systemic recurrences.

Adenocarcinoma↗
PubMed1999

The role of magnetic resonance imaging in the management of traction injuries to the adult brachial plexus.

Magnetic resonance imaging (MRI) of the cervical spine and brachial plexus was performed on 26 consecutive patients presenting with traction injuries of the brachial plexus during 1996 and 1997. These included T1 and T2 weighted coronal, sagittal and axial images of the cervical spine and coronal images of the brachial plexus. The results were compared with surgical findings, intraoperative neurophysiology, and subsequent clinical progress. Operations for exploration and repair have been performed in 23 and 26 patients scanned. Evidence of root avulsion was seen in 11 patients in the form of displacement or oedema of the spinal cord, haemorrhage or scarring within the spinal canal, absence of roots in the intervertebral foramena, and meningoceles. Characteristic abnormalities were evident in the MR scans of all cases where exploration confirmed some root avulsions. There were no false positives. MRI underestimated the number of individual roots avulsed; sensitivity was 81%. Post-ganglionic lesions were seen as swelling on T1 images associated with increasing signal on T2 images. It was usually possible to define the level of the injury within the plexus. This study suggests that MR imaging, performed early after traction injury to the brachial plexus, provides useful additional information towards establishing the level of the lesion. It also provides information about injury to the plexus outside the spinal canal.

Adult↗
PubMed1999

Adjuvant dose-intense chemotherapy with peripheral blood stem cell support in stage II-III breast cancer with five to nine involved axillary lymph nodes.

The purpose of this study is to determine outcomes for patients with high-risk nonmetastatic breast cancer undergoing high-dose chemotherapy with peripheral blood stem cell support. Forty-three patients with stage II-III disease, five to nine positive axillary lymph nodes, and a median age of 44 years (range, 27-60 years) were enrolled in a study that included: 1) standard dose doxorubicin, 5-fluorouracil, and methotrexate adjuvant therapy; 2) cyclophosphamide, etoposide, filgrastim, and peripheral blood stem cell harvest; and 3) high-dose cyclophosphamide, thiotepa, and carboplatin (CTCb) followed by peripheral blood stem cell infusion. All 43 patients received doxorubicin, 5-fluorouracil, and methotrexate, 42 (98%) received etoposide, and 41 (95%) received CTCb. Thirty-two patients (74%) are alive, 28 (65%) without relapse at a median of 55 months (range, 41-87 months). Two died (5%) of treatment-related causes, (subclavian catheter complication after etoposide and late radiation pneumonitis), and nine other deaths (21%) were associated with recurrent breast cancer. The probabilities of overall and event-free survival at 4 years were 0.77 and 0.67, respectively, compared with 0.82 and 0.69, respectively, for 72 similar patients with 10 or more positive axillary nodes receiving the same sequence of therapy. Thus, patients with five to nine positive axillary lymph nodes have a similar risk of failure after high-dose chemotherapy and peripheral blood stem cell support as patients with 10 or more positive axillary lymph nodes.

Adult↗
PubMed1999

Single-agent paclitaxel in patients with metastatic breast cancer receiving high-dose chemotherapy with peripheral blood stem cell support.

The purpose of this trial was to determine the effects of paclitaxel in patients with newly diagnosed metastatic breast cancer scheduled to receive high-dose chemotherapy with peripheral blood stem cell support. Eighty-four patients received anthracycline-based induction and two doses of paclitaxel at 170 mg/m2 (n = 52) or 250 mg/m2 (n = 32). Eighty-two (98%) received cyclophosphamide and etoposide (n = 50) or paclitaxel and cyclophosphamide (n = 32) with granulocyte colony-stimulating factor for mobilization of peripheral blood stem cells, and 79 (94%) received cyclophosphamide, thiotepa, and carboplatin with peripheral blood stem cell support. One patient (1%) died of infection and 56 (67%) died of progressive disease. For patients with measurable disease, the complete response rate was 21% after induction and 29% after paclitaxel (p = 0.54). Results were compared with those of 125 patients who received the same sequence of therapy without paclitaxel. The complete response rate after high-dose chemotherapy was 54% for patients receiving paclitaxel and 62% for those not receiving paclitaxel (p = 0.60). The probabilities of overall survival and event-free survival at 3 years for patients receiving paclitaxel were 46% and 24%, respectively, compared with 54% and 22%, respectively, for patients not receiving paclitaxel (p = 0.62). Further trials evaluating this dose and schedule of paclitaxel in patients with metastatic breast cancer receiving high-dose chemotherapy are not warranted.

Adult↗
PubMed1999

Effect of CD34(+) cell dose on resource utilization in patients after high-dose chemotherapy with peripheral-blood stem-cell support.

PURPOSE: The mean time to neutrophil and platelet recovery for patients receiving high-dose chemotherapy (HDC) supported with peripheral-blood stem cells (PBSCs) is related to the dose of CD34(+) cells infused. The effect of cell dose on resource utilization after transplantation has not been previously reported. MATERIALS AND METHODS: We assessed CD34(+) cell dose and resource utilization for 1,317 patients undergoing transplantation with PBSCs from April 1991 to June 1997. PBSCs were collected after mobilization with chemotherapy and recombinant human granulocyte colony-stimulating factor (rhG-CSF). Daily measurement of the CD34(+) content of the PBSC collection was performed by a central laboratory using a single CD34(+) analysis technique. Resource utilization included engraftment parameters, length of stay, and transfusion requirements for 100 days posttransplantation. Analysis included descriptive statistics and multiple regression. RESULTS: Mean patient age was 47 years, and 86% of patients were female. Median cell dose was 3.6 x 10(6)/kg and 13.2 x 10(6)/kg for patients receiving less than 5.0 x 10(6) CD34(+) cells/kg and 5.0 x 10(6) or more CD34(+) cells/kg, respectively. Patients receiving less than 5. 0 x 10(6) CD34(+) cells/kg were more likely to have metastatic breast cancer or non-Hodgkin's lymphoma and required more platelet and RBC transfusions, 3.3 more hospital days, and increased antibiotic and antifungal use. In univariate analysis, the cost of care was $41,516 (+/-$20,876 SD) and $32,382 (+/-$16,353 SD) for patients with less than 5.0 x 10(6) CD34(+) cells/kg and 5.0 x 10(6) or more CD34(+) cells/kg, respectively. In multivariate analysis, patients with less than 5.0 x 10(6) CD34(+) cells/kg had an increase in costs of $5,062 (+/- $1,262 SE). CONCLUSION: Infusion of more than 5.0 x 10(6) CD34(+) cells/kg was associated with a reduction in resource utilization. Achieving a target of 5.0 x 10(6) CD34(+) cells/kg should have important clinical and economic benefits for patients.

Adolescent↗
PubMed1998

Molecular analysis of cellulose biosynthesis in Arabidopsis.

Cellulose, an abundant, crystalline polysaccharide, is central to plant morphogenesis and to many industries. Chemical and ultrastructural analyses together with map-based cloning indicate that the RSW1 locus of Arabidopsis encodes the catalytic subunit of cellulose synthase. The cloned gene complements the rsw1 mutant whose temperature-sensitive allele is changed in one amino acid. The mutant allele causes a specific reduction in cellulose synthesis, accumulation of noncrystalline beta-1,4-glucan, disassembly of cellulose synthase, and widespread morphological abnormalities. Microfibril crystallization may require proper assembly of the RSW1 gene product into synthase complexes whereas glucan biosynthesis per se does not.

Amino Acid Sequence↗