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Biomedical subjects

D J Brown

Publications and source records attributed to D J Brown.

At least 37 records · Page 2Linked to original sources
PubMed2001

Theileria annulata: attenuation of a schizont-infected cell line by prolonged in vitro culture is not caused by the preferential growth of particular host cell types.

Flow cytometry and monoclonal antibodies to bovine leucocyte surface antigens were used to identify the types of host cells that the sporozoites of Theileria annulata infect in cattle, to determine whether virulent schizont-infected cell lines (lines) differed phenotypically from avirulent lines, and to establish whether attenuation in vitro was accompanied by the preferential growth of particular host cell types. The surface antigens of four pairs of T. annulata (Ta) (Hisar) lines derived ex vivo and in vitro, including the virulent ex vivo-derived Ta Hisar S45 line, were consistent with a myeloid origin for all lines, irrespective of their derivation. The profiles of lines derived from cattle inoculated with a virulent line showed that the schizonts liberated from inoculated cells had transferred to myeloid cells. A number of other lines infected with different stocks of T. annulata expressed myeloid markers; a single line expressed CD21, a B cell marker. During prolonged in vitro culture, the parasites in the ex vivo (virulent)- and in vitro (avirulent)-derived Ta Hisar S45 myeloid lines became clonal, as defined by glucose phosphate isomerase (GPI) polymorphism, and the virulent line became attenuated. The two lines retained phenotypic profiles indicative of a myeloid origin but coexpressed some lymphoid antigens (CD2, CD4, CD8), although not CD3. Cloned schizont-infected lines, representing the three parasite GPI isotypes which constituted the virulent line, expressed similar patterns of myeloid and lymphoid markers to the virulent parent line. Some schizont-infected clones failed to establish as lines during the early weeks of culture because the cells died as the parasites differentiated into merozoites at 37 degrees C, the temperature at which schizont-infected cells normally grow exponentially. These results provided no evidence that prolonged culture induces preferential growth or loss of particular host cell types. However, a number of the alterations in host cell surface antigens induced by prolonged culture were shown to be linked to permanent changes in the parasite genome.

Animals↗
PubMed2001

Overexpression of matrix metalloproteinase-10 and matrix metalloproteinase-3 in human diabetic corneas: a possible mechanism of basement membrane and integrin alterations.

We have previously described decreased immunostaining of nidogen-1/entactin; laminin chains alpha1, alpha5, beta1,gamma1; and epithelial integrin alpha3beta1 in human diabetic retinopathy (DR) corneas. Here, using 142 human corneas, we tested whether these alterations might be caused by decreased gene expression levels or increased degradation. By semiquantitative reverse transcription-polymerase chain reaction, gene expression levels of the alpha1, alpha5, and beta1 laminin chains; nidogen-1/entactin; integrin alpha3 and beta1 chains in diabetic and DR corneal epithelium were similar to normal. Thus, the observed basement membrane and integrin changes were unlikely to occur because of a decreased synthesis. mRNA levels of matrix metalloproteinase-10 (MMP-10/stromelysin-2) were significantly elevated in DR corneal epithelium and stroma, and of MMP-3/stromelysin-1, in DR corneal stroma. No such elevation was seen in keratoconus corneas. These data were confirmed by immunostaining, zymography, and Western blotting. mRNA levels of five other proteinases and of three tissue inhibitors of MMPs were similar to normal in diabetic and DR corneal epithelium and stroma. The data suggest that alterations of laminins, nidogen-1/entactin, and epithelial integrin in DR corneas may occur because of an increased proteolytic degradation. MMP-10 overexpressed in the diabetic corneal epithelium seems to be the major contributor to the observed changes in DR corneas. Such alterations may bring about epithelial adhesive abnormalities clinically seen in diabetic corneas.

Adult↗
PubMed2001

Efficacy of low-intensity pulsed ultrasound in the prevention of osteoporosis following spinal cord injury.

Ultrasound (US), a high-frequency acoustic energy traveling in the form of a mechanical wave, represents a potential site-specific intervention for osteoporosis. Bone is a dynamic tissue that remodels in response to applied mechanical stimuli. As a form of mechanical stimulation, US is anticipated to produce a similar remodeling response. This theory is supported by growing in vitro and in vivo evidence demonstrating an osteogenic effect of pulsed-wave US at low spatial-averaged temporal-averaged intensities. The aim of this study was to investigate whether low-intensity pulsed US could prevent calcaneal osteoporosis in individuals following spinal cord injury (SCI). Fifteen patients with a 1-6 month history of SCI were recruited. Active US was introduced to one heel for 20 min/day, 5 days/week, over 6 weeks. The contralateral heel was simultaneously treated with inactive US. Patients were blind to which heel was being actively treated. Active US pulsed with a 10 microsec burst of 1.0 MHz sine waves repeating at 3.3 kHz. The spatial-averaged temporal-averaged intensity was set at 30 mW/cm(2). Bone status was assessed at baseline and following the intervention period by dual-energy X-ray absorptiometry and quantitative US. SCI resulted in significant bone loss. Bone mineral content decreased by 7.5 +/- 3.0% in inactive US-treated calcanei (p < 0.001). Broadband US attenuation and speed of sound decreased by 8.5 +/- 6.9% (p < 0.001) and 1.5 +/- 1.3% (p < 0.001), respectively. There were no differences between active and inactive US-treated calcanei for any skeletal measure (p > 0.05). These findings confirm the negative skeletal impact of SCI, and demonstrate that US at the dose and mode administered was not a beneficial intervention for SCI-induced osteoporosis. This latter finding may primarily relate to the inability of US to effectively penetrate the outer cortex of bone due to its acoustic properties.

Absorptiometry, Photon↗
PubMed2001

Longidorus cretensis n. sp. (Nematoda: Longidoridae) from a vineyard infected with a foliar 'yellow mosaic' on Crete, Greece.

A description is provided of Longidorus cretensis n. sp., a bisexual species associated with grapevines in Crete, Greece. The species is characterised by a body length of 6.3-8.7 mm, head flattened anteriorly and continuous with the body profile, amphids pocket-shaped and not bilobed, a posteriorly situated guide-ring, posteriorly situated oesophageal glands, and a tail bluntly rounded to hemispherical. Xiphinema index was present throughout the vineyard, but L. cretensis n. sp. occurred only in an area where the grapevine foliage exhibited a 'yellow mosaic' disease, and in association with X. pachtaicum from the rhizosphere of an olive tree growing adjacent to the vineyard. Nematode-transmitted virus was not recovered from weed species growing in the vicinity of the olive tree, or by bait-testing soil collected from the rhizosphere of the tree. Population densities of L. cretensis n. sp. were similar under olive and grapevine, but twice as many adult specimens were recovered from soil samples collected in the vineyard. Three quarters of L. cretensis specimens were present at 21-40 cm depth under olive, whereas a similar proportion of the population was equally distributed under grapevine at 21-40 cm and 41-60 cm depths.

Animals↗
PubMed2001

Description of the male and first-stage juvenile of Longidorus intermedius Kozlowska & Seinhorst, 1979 (Nematoda: Dorylaimida), and notes on its morphology and distribution.

Longidorus intermedius Kozlowska & Seinhorst, 1979 is redescribed from specimens recovered from oak (Quercus L.) forests in Bulgaria. The male and the first-stage juvenile were recorded for the first time, as were populations from Macedonia and Turkey. L. intermedius is identified here as the first species in the genus with only three juvenile stages and a pan-European distribution. The species was recovered from 36 of 46 oak forests in Bulgaria, found associated with each of nine oak species sampled and reached population densities of up to 289 specimens per 200 cm(3) of soil. The distribution of L. intermedius in Bulgaria, and in other countries, suggests that this species, like Xenocriconemella macrodora (Taylor, 1936) and probably L. aetnaeus Lamberti, Agostinelli & Vinciguerra, 1986, can be used as an ecological indicator for habitats where Quercus associations represent a primary vegetation type.

Animals↗
PubMed2001

Identification of cell types in human diseased corneas.

PURPOSE: Activated myofibroblasts and macrophages are often found in corneal wound models. The current study was performed to determine whether human diseased corneas that had active tissue remodeling and enzyme activities also possessed myofibroblasts, macrophages, major histocompatibility complex class II cells, and/or CD-68-positive cells. METHODS: Normal, keratoconus, keratoconus with hydrops, bullous keratopathy, map-dot-fingerprint dystrophy, failed grafts, and acid burn/neovascularized corneas were collected, frozen in OCT, sectioned, and stained with antibodies to alpha smooth muscle actin (myofibroblast marker), CD14 (macrophage marker), CD68 (lysosomal membrane marker), and HLA-DR (major histocompatibility complex class II cells). Selective histochemical stains identified lysosomal enzymes. RESULTS: Normal and map-dot-fingerprint dystrophy corneas lacked antibody and enzyme staining. Keratoconus corneas were positive for CD68, HLA-DR, and lysosomal enzymes but were negative for CD14 and smooth muscle actin. Bullous keratopathy corneas had CD68-, CD14-, and HLA-DR-positive cells, relatively normal enzyme levels, and were smooth muscle actin-negative. Failed graft corneas had significant numbers of CD68-, CD14-, and HLA-DR-positive cells and increased acid phosphatase, but these corneas were smooth muscle actin-negative. Ulcerated and vascularized corneas had positive staining with all antibodies that were examined. Cultured stromal cells from normal corneas were CD68-positive, CD14-negative, and alpha smooth muscle actin-negative, and they produced lysosomal enzymes. CONCLUSIONS: The current study demonstrates that increased presence of lysosomal enzymes, corneal remodeling, and fibrosis can occur in the absence of myofibroblasts and/or macrophages.

Acid Phosphatase↗
PubMed2001

Simple treatment for torus fractures of the distal radius.

Torus (buckle) fractures of the distal radius are common in childhood. Based on the results of a postal questionnaire and a prospective, randomised trial, we describe a simple treatment for this injury, which saves both time and money. Over a six-month period, we randomised 201 consecutive patients with this injury to treatment with either a traditional forearm plaster-of-Paris cast or a 'Futura-type' wrist splint. All patients were treated for a period of three weeks, followed by clinical and radiological review. There was no difference in outcome between the two groups, and all patients had a good result. Only one patient did not tolerate the splint which was replaced by a cast. The questionnaire showed a marked variation in the way in which these injuries are treated with regard to the method and period of immobilisation, the number of follow-up visits and radiographs taken. We suggest that a 'Futura-type' wrist splint can be used to treat these fractures. The patient should be reviewed on the following day to confirm the diagnosis and to give appropriate advice. There is no evidence that further follow-up is required. This simple treatment has major benefits in terms of cost and reduction of the number of attendances.

Adolescent↗
PubMed2001

Transtracheal oxygenation : an alternative to endotracheal intubation during cardiac arrest.

STUDY OBJECTIVES: Because efforts to secure adequate arterial oxygenation during cardiac resuscitation are more important than efforts to promote CO(2) elimination, we investigated whether continuous transtracheal oxygenation (TTO) could represent a potentially simpler alternative to conventional positive-pressure ventilation with 100% O(2) through an endotracheal tube. DESIGN: Controlled and randomized. SETTING: Animal laboratory. PARTICIPANTS: Thirty male Sprague-Dawley rats. INTERVENTIONS: The technique for TTO was initially developed and tested in five rats. A model of ventricular fibrillation (VF) was then used to compare the effects of TTO (n = 5) with the effects of O(2) delivery through an endotracheal tube as part of positive-pressure ventilation (n = 5) or through a mask without additional airway intervention (n = 5). VF was induced and left untreated for 4 min, after which chest compression and one of the three oxygenation interventions was started. Defibrillation was attempted after 6 min of chest compression. In a subsequent series, defibrillation was attempted after 10 min of chest compression in rats treated with either TTO (n = 5) or endotracheal intubation (ET; n = 5). MEASUREMENT AND RESULTS: TTO and ET secured adequate arterial PO(2) during chest compression (213 +/- 77 mm Hg and 154 +/- 36 mm Hg; not significant), whereas the mask yielded an arterial PO(2) of only 49 +/- 38 mm Hg (p < 0.05). Each rat treated with TTO or ET was successfully resuscitated and survived the postresuscitation interval, but none of the rats treated with the mask survived. TTO maintained its efficacy after increased duration of chest compression. CONCLUSION: TTO was as effective as conventional positive-pressure ventilation with 100% O(2) for securing oxygenation, resuscitation, and short-term survival and more effective than O(2) delivered through a mask.

Animals↗
PubMed2001

Radiofrequency tissue reduction of the palate in patients with moderate sleep-disordered breathing.

OBJECTIVE: Radiofrequency volumetric reduction of the palate has been advocated as a treatment for mild sleep-disordered breathing (SDB). Our study examines the efficacy of this procedure on patients with mostly moderate SDB. DESIGN: Prospective, nonrandomized, consecutive series. SETTING: St. Boniface Hospital, Sleep Disorders Centre, University of Manitoba, Winnipeg. METHOD: Twelve patients with polysomnographically proven moderate SDB were given a total of 2400 to 3600 joules of radiofrequency energy to their soft palate over two to three treatments. Follow-up examined the effect of treatment on subjective and objective parameters including the Epworth Sleepiness Scale, loudness of snoring, Apnea-Hypopnea Index (AHI), and Arousal Index. RESULTS: Two of 12 patients had a good objective response to treatment in that their AHI dropped by more than 50% and to a value of less than 20. However, none of the patients claimed to have a satisfactory subjective response. There was a slight reduction in the mean AHI from 31.2+/-5.1 to 25.3+/-4.2 (p < .05), but no clinically significant difference was found between pre- and post-treatment groups with respect to other sleep parameters. There was no improvement in daytime sleepiness or snoring. CONCLUSIONS: Radiofrequency tissue ablation of redundant soft palate tissues lacks clinical efficacy in patients with moderate SDB.

Adult↗
PubMed2001

'Worms' that transmit viruses.

Plant-parasitic nematodes transmit viruses that hit hard on global agriculture. Both the nematodes and the viruses they carry persist in the soil for a long time with the only remedy being highly toxic chemicals. Fundamental new research may offer the hope of developing safer control strategies.

Agriculture↗
PubMed2001

Survey of future injectables.

There has been an explosion in the technology of injectable filler materials for soft tissue augmentation of the face in the past decade. As a result, this is an exciting field and has provided surgeons who treat the aging face with newer, minimally invasive tools and techniques to augment the soft tissues of the face. In general, there are four classes of materials available for soft-tissue augmentation: synthetic, xenogeneic, homogeneic, and autogeneic. Moreover, within each class, these materials can be further divided, according to their longevity, into permanent materials, materials that last an undefined prolonged time, and temporary fillers. These products allow the surgeon and the patient to make choices that will give the best cosmetic results.

Collagen↗
PubMed2000

Pretransplant systemic inflammation and acute rejection after renal transplantation.

BACKGROUND: There are presently no established pre-transplant tests that consistently identify patients who may be at increased risk for acute rejection episodes after renal transplantation. We studied whether pretransplant serum levels of C-reactive protein (CRP), a marker for the presence of systemic inflammation, would predict the occurrence of acute rejection episodes after renal transplantation. METHODS: Pretransplant serum was tested for CRP level in 97 consecutive renal transplant recipients. Time to acute rejection after transplantation was stratified by CRP level and compared using the Kaplan-Meier method. In addition, Cox regression multivariate analysis was performed to assess whether any pretransplant covariates could independently predict the subsequent occurrence of acute rejection episodes. RESULTS: Pretransplant mean CRP levels were higher in patients who subsequently had a rejection episode versus those who had no rejection (22.2+/-2.9 vs. 11.7+/-1.8 microg/ml, respectively, P=0.003). Patients less than the median CRP value had a significantly longer time to rejection compared to those with higher CRP levels (P=0.002). Similarly, patients within the lowest CRP quartile had longer times to rejection when compared with the highest quartile (P=0.006). Cox proportional hazards regression multivariate analysis identified CRP level as the only independent pretransplant risk factor for rejection identified (P=0.044). CONCLUSIONS: Pretransplant systemic inflammation as manifested by elevated serum CRP level independently predicts the risk of acute rejection after renal transplantation and may be useful in stratifying patients at the time of transplantation according to immunological risk. Thus, assessment of pretransplant systemic inflammatory status may be helpful in prospective individualization of immunosuppression therapy after renal transplantation.

Acute Disease↗
PubMed2000

Necrospermia and chronic spinal cord injury.

OBJECTIVE: To determine whether improvement in quality of semen over 4 consecutive days of electroejaculation in men with chronic spinal cord injury (SCI) was consistent with epididymal necrospermia. DESIGN: Prospective study of a random sample of men with SCI. SETTING: A southeastern Australian SCI management center in collaboration with the specialist andrology service of a university-based department of obstetrics and gynecology in a tertiary referral hospital. PATIENT(S): Nine men with chronic spinal cord injury. INTERVENTION(S): Semen samples were obtained by using electroejaculation, and testicular biopsy samples were obtained by using fine-needle tissue aspiration. MAIN OUTCOME MEASURE(S): Semen analysis was performed according to World Health Organization criteria. Testicular biopsy and electron microscopy were done by using standard techniques. RESULT(S): During up to 4 days of consecutive-day electroejaculation, sperm motility and viability in semen obtained from men with chronic SCI increased by an average of 23% on days 2 and 3. The severity of the degenerative changes and the numbers of spermatozoa affected on day 1 became less marked by day 4. The changes were not present in late spermatids obtained from testicular biopsies. CONCLUSION(S): The asthenospermia of chronic SCI is similar to epididymal necrospermia and can be improved by consecutive-day electroejaculation.

Adult↗
PubMed2000

Virulence characterization of a strain of Salmonella enterica subspecies houten (subspecies IV) with chromosomal integrated Salmonella plasmid virulence (spv) genes.

The Salmonella plasmid virulence genes (spv) are commonly found on plasmids contained in a small number of serotypes of Salmonella belonging to subspecies I, where they are important for survival within macrophages and the establishment of successful systemic infection. However, in this study, spv genes were detected by the polymerase chain reaction in the chromosome of a plasmid-free strain of S. IV 16:z4, z32:- (Salmonella subspecies IV). The full range of spv genes (spvR, spvA, spvB, spvC and spvD) was demonstrated, but a 216-bp deletion, accompanied by an insertion of 59-bp cryptic DNA, was present in spvA. S. IV 16:z4, z32:- was avirulent in mice and did not become virulent with the introduction of a fully functionally serotype-associated virulence plasmid (SAP) from S. typhimurium. By use of an spvRAB'-chloramphenicol acetyl transferase fusion gene, it was demonstrated that S. IV 16:z4, z32:- did not express the spv genes. Salmonella subspecies IV is monophasic, and in phylogenetic analyses it clusters distantly to Salmonella subspecies I, where all the serotypes that normally carry SAPs are found. The mechanisms by which spv genes have been transferred to this serotype remain unknown.

Animals↗
PubMed2000

Criconematidae (Nematoda) from oak forests in two nature reserves in Russia.

Seven criconematid species: Ogma menzeli, Criconema annuliferum, C. princeps, Criconemoides pleriannulatus, Mesocriconema solivagum, M. xenoplax and Xenocriconemella macrodora were recovered from soil samples collected from oak forests in the Shulgan-Tash and Voronezh nature reserves in Russia. Examination of C. pleriannulatus by SEM confirmed the absence of submedian lobes and revealed the presence of a small lip annule; juveniles exhibit fringe-like cuticular ornamentation of the annules. Ogma menzeli and C. pleriannulatus are new geographical records for Russia, and all species have already been reported in association with different oak species with the exception of M. solivagum and C. pleriannulatus. Criconemoides mutabilis Eroshenko, 1980 is proposed as ajunior synonym of C. pleriannulatus Ebsary, 1979.

Animals↗
PubMed2000

Longidorus camelliae n. sp. (Nematoda: Longidoridae) associated with ornamental cultivars of Camellia japonica L. growing in a nursery at Fuyang, Zhejiang Province, eastern China.

A description is provided of Longidorus camelliae n. sp., a bisexual species associated with ornamental cultivars of Camellia japonica L. growing in Fuyang, Zhejiang Province, eastern China. The species is characterised by its small body length (1.83-3.54 mm), narrow (6-10 microm), anteriorly flattened, continuous head region, non-bilobed amphidial pouches, medium odontostyle length (80-91, microm) and elongate, conoid tail (32-39 microm; c' = 1.1-1.4). Males are characterised by having short spicules (44-48 microm) and a row of seven supplements. The species has only three juvenile development stages.

Animals↗
PubMed2000

Effect of combination antiretroviral therapy on T-cell immunity in acute human immunodeficiency virus type 1 infection.

T-cell responses were evaluated prospectively in 41 patients with acute human immunodeficiency virus type 1 (HIV-1) infection (30 untreated and 11 receiving zidovudine, lamivudine, and indinavir) and in 38 uninfected adults. By 6-12 months, treated patients had significantly greater median Candida and tetanus lymphoproliferative responses (stimulation index [SI], 76 and 55, respectively) than did untreated patients (SI, 7 and 6, P=.02 and.001, respectively), and the responses of treated patients surpassed those of uninfected adults (SI, 19 and 32, P= .002 and .101, respectively). Unlike the patients in the untreated group, the patients in the treated group mounted a 6-fold increased HIV-1 p24 response (SI increase, 1.0 to 5.7, P= .01) within 3 months. HIV-1-specific cytotoxicity remained detectable in most treated patients. Thus, combination therapy administered within 3-4 months of infection was associated with improved T-cell memory responses that were distinct from those of untreated patients. The amplified HIV-1-specific T-cell responses may help maintain cytotoxic activities.

Acute Disease↗