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Biomedical subjects

D M Allen

Publications and source records attributed to D M Allen.

At least 19 recordsLinked to original sources
PubMed2004

Utilization of beef from different cattle phenotypes to produce a guaranteed tender beef product.

Cattle (n = 303) were visually selected from four feed yards to represent six phenotypes (English [EN; n = 50], 3/4 English-1/4 Brahman [ENB; n = 52], 1/2 English-1/2 Exotic [ENEX; n = 56], 1/2 English-1/4 Exotic-1/4 Brahman [ENEXB; n = 47], 3/4 Exotic-1/4 Brahman [EXB; n = 49], and 1/2 Exotic-1/4 English-1/4 Brahman [EXENB; n = 49]). Carcasses were processed at a commercial beef packing facility, and strip loins were collected after 48-h chilling. Strip loins were aged for 14 d at 2 degrees C and frozen at -20 degrees C for 3 to 5 d before three 2.5-cm-thick steaks were cut for Warner-Bratzler shear force (WBSF) determinations and sensory evaluations. Phenotype EN had the highest (P < 0.05) adjusted fat thickness, and EXB had adjusted fat thickness that was lower (P < 0.05) than all other phenotypes except EXENB. Carcasses of EN and ENB had smaller (P < 0.05) longissimus muscle areas than phenotypes ENEX, EXB, and EXENB. Phenotype EN produced carcasses with the highest (P < 0.05) numerical yield grade, whereas carcasses originating from phenotype EXB had lower (P < 0.05) numerical yield grades than all other phenotypes except ENEX. No differences (P > 0.05) were found among phenotypes for mean WBSF values or sensory panel ratings for initial and sustained tenderness, initial and sustained juiciness, beef flavor characteristics, and overall mouthfeel. More than 90% of steaks from carcasses of all phenotypes had WBSF values less than 3.6 kg when cooked to an internal cooked temperature of 70 degrees C. Results from this study indicated that all phenotypes represented in this study could be managed to produce tender beef.

Animals↗
PubMed2002

Effects of the transportation of beef cattle from the feedyard to the packing plant on prevalence levels of Escherichia coli O157 and Salmonella spp.

Two hundred steers and heifers from a large feedyard (65,000-head capacity) were used to determine the prevalence levels of enterohemorrhagic Escherichia coli O157 (EHEC O157) and Salmonella spp. prior to and after shipping to a commercial packing facility. Two samples, a ventral midline hide swab and a fecal sample, were aseptically collected from each animal 2 weeks prior to the date of transportation and at the packing plant immediately after exsanguination. Samples were collected from all trailers (n = 46) before animals were loaded for transport to the packing facility. The average prevalence levels of EHEC O157 on hides (18%) and in feces (9.5%) at the feedyard decreased (P > 0.05) at the packing plant to 4.5 and 5.5%, respectively. The average prevalence levels of Salmonella spp. on hides (6%) and in feces (18%) at the feedyard increased to 89 and 46%, respectively, upon arrival at the packing plant. Average prevalence levels for EHEC O157 and Salmonella spp. on the trailers were 5.43 and 59%, respectively. The results of this study demonstrate that transportation may be a potential stressor for cattle, as evidenced by the increased shedding of Salmonella spp.

Animals↗
PubMed2001

Ataxia telangiectasia mutated is essential during adult neurogenesis.

Ataxia telangiectasia (A-T) is an autosomal recessive disease characterized by normal brain development followed by progressive neurodegeneration. The gene mutated in A-T (ATM) is a serine protein kinase implicated in cell cycle regulation and DNA repair. The role of ATM in the brain and the consequences of its loss on neuronal survival remain unclear. We studied the role of ATM in adult neural progenitor cells in vivo and in vitro to define the role of ATM in dividing and postmitotic neural cells from Atm-deficient (Atm(-/-)) mice in a physiologic context. We demonstrate that ATM is an abundant protein in dividing neural progenitor cells but is markedly down-regulated as cells differentiate. In the absence of ATM, neural progenitor cells of the dentate gyrus show abnormally high rates of proliferation and genomic instability. Atm(-/-) cells in vivo, and in cell culture, show a blunted response to environmental stimuli that promote neural progenitor cell proliferation, survival, and differentiation along a neuronal lineage. This study defines a role for ATM during the process of neurogenesis, demonstrates that ATM is required for normal cell fate determination and neuronal survival both in vitro and in vivo, and points to a mechanism for neuronal cell loss in progressive neurodegenerative diseases.

Animals↗
PubMed2000

Ultrastructural identification of synapses between mitral/tufted cell dendrites.

Asymmetrical, type 1 synapses between mitral and/or tufted (M/T) cell dendrites were observed in the glomerular layer (GL) and juxtaglomerular external plexiform layer (EPL) of salamander olfactory bulb sections. The dendrites had electron-lucent cytoplasm containing regularly-arrayed microtubules and spherical translucent vesicles. The vesicles were clustered against a thin pre-synaptic density that was aligned with a 17-20 nm-wide synaptic cleft and a thicker post-synaptic density. These dendrodendritic synapses could be a source of the delayed, prolonged excitation that originates from the GL/EPL. During spatiotemporal encoding of odor stimuli, they could amplify or synchronize M/T cell responses.

Ambystoma↗
PubMed2000

Interactions between forage and wet corn gluten feed as sources of fiber in diets for lactating dairy cows.

Twelve early lactation Holstein cows (4 fistulated) were used in replicated 4x4 Latin squares with 4-wk periods to determine the effective neutral detergent fiber (NDF) content of wet corn gluten feed and to measure the effect of forage particle size on ruminal mat consistency and passage rate of wet corn gluten feed. Diets were 1) 23.3% NDF (17.4 percentage units of NDF from alfalfa silage), 2) diet 1 plus 11.1 additional percentage units of NDF from alfalfa silage, 3) diet 1 plus 10.7 percentage units of NDF from wet corn gluten feed, and 4) 8.6 percentage units of NDF from alfalfa silage plus 8.9 percentage units of NDF from coarsely chopped alfalfa hay and 10.7 percentage units of NDF from wet corn gluten feed. The calculated effective NDF factor for wet corn gluten feed, using change in milk fat concentration per unit change in NDF, was 0.74 compared with an assumed 1.0 for alfalfa silage. Rumination activity was measured to calculate a physically effective NDF factor for wet corn gluten feed, which was only 0.11 compared with 1.0 for alfalfa silage. Physically effective NDF also was determined for wet corn gluten feed by wet sieving; 22% of the particles were retained on the 3.35-mm screen or greater. Ruminal mat consistency increased and passage rate of wet corn gluten feed decreased with added hay. The inclusion of chopped alfalfa hay to a diet containing wet corn gluten feed increased ruminal mat consistency, rumination activity, and slowed passage rate, resulting in greater ruminal digestion of NDF from wet corn gluten feed. Depending on the response variable, the effectiveness of NDF from wet corn gluten feed varied from 0.11 to 0.74.

Animal Feed↗
PubMed2000

Effects of hydrolyzed spray dried red blood cells in milk replacer on calf intake, body weight gain, and efficiency.

An alternative protein ingredient based on spray-dried, hydrolyzed red blood cells was evaluated in calf milk replacers. Two experiments were conducted to determine the value of the ingredient on intake, growth, and feed efficiency in dairy calves. In experiment 1, Holstein bull calves (n = 120) were fed calf milk replacer containing 0, 11, 22, or 43% of crude protein as spray dried hydrolyzed red blood cells. Calves were fed 454 g/d of experimental milk replacer reconstituted to 12% dry matter plus a conventional calf starter for 28 d. Body weight gain, intake of milk replacer and calf starter, feed efficiency, fecal scores, and days scouring were unaffected by source of protein. In experiment 2, Holstein calves (n = 69) at the University of Minnesota, Crookston and Waseca were fed milk replacer containing 0, 22, or 43% of crude protein as spray dried hydrolyzed red blood cells. Calves were fed 454 g/d of experimental milk replacer reconstituted to 12% dry matter plus a conventional calf starter containing 0 or 25% alfalfa meal for 35 d. No calves died during the study. Body weight gain, feed efficiency, intake of calf starter and milk replacer, fecal scores, and days scouring were unaffected by increasing hydrolyzed red blood cells in milk replacer. Similar performance of all calves indicated that spray dried hydrolyzed red blood cells can replace up to 43% of crude protein from whey protein concentrate without detrimental effects on animal performance.

Animal Feed↗
PubMed2000

Women and cardiovascular disease.

Cardiovascular disease remains the number one killer in the United States. The face of the person with cardiovascular disease is changing. No longer is the middle-aged man at highest risk. Current data reveal that women, especially postmenopausal women, are at highest risk for cardiovascular disease. This article identifies the differences noted between men and women with cardiovascular disease, including effects in presentation, identification, and treatment.

Clinical Trials as Topic↗
PubMed1999

Increasing utilisation efficiency of ferric chloride etchant in industrial photochemical machining.

The environmental effects of photochemical machining (PCM) can be appreciable in view of the nature of the industry whereby various chemicals are used in the preparation and cleaning of metal surfaces, photographic processing of phototooling, coating and selective removal (development) of photoresists, etching through apertures in the resist stencils and stripping of resist after etching. This paper concerns the environmental impact of ferric chloride, the most commonly used etchant in PCM, and is believed to be the first quantitative analysis for the PCM industry. The findings showed that more than half of the PCM companies used regeneration of ferric chloride etchant and 76.3% of companies were prepared to use a more environment-friendly regeneration system at a higher overall cost. Regarding ferric chloride consumption, it was found that the performance of companies varies greatly: companies using regeneration were, on average, nearly seven times (340.8% compared with 51.1%) more efficient than those that do not regenerate, and the most efficient company used 135 times less etchant than the least efficient company. The findings of this study and the analysis carried out can be used by PCM companies as a benchmark in assessing their environmental performance with respect to etchant consumption efficiency.

Benchmarking↗
PubMed1998

Outcomes after severe trauma at a northern Canadian regional trauma centre.

OBJECTIVE: To evaluate outcomes of trauma patients at a northern community trauma referral centre that does not meet several of the guidelines for a trauma centre. DESIGN: A retrospective study. SETTING: Sudbury General Hospital in northern Ontario. PARTICIPANTS: All trauma patients admitted between 1991 and 1994 who had an Injury Severity Score (ISS) greater than 12. OUTCOME MEASURES: Actual survival to discharge was compared to survival predicted by TRISS analysis. Z, W and M scores were calculated by standard TRISS techniques. RESULTS: Of 526 patients with an ISS greater than 12, 416 (79%) were suitable for TRISS analysis. Of these 416 patients, 310 (74%) were men. The mean age was 39 years. Two hundred and sixty-one (63%) patients were admitted directly to the Sudbury General Hospital, whereas 155 (37%) were transferred from other hospitals. The leading causes of injury were motor vehicle-traffic accidents in 48%, motor vehicle-nontraffic in 21% and falls in 8%. Overall, there were more unexpected survivors than patients who died. The Z score for survivors was 4.95, and the W score was 5.65. CONCLUSIONS: In the setting of a geographically isolated, medium-volume trauma centre where blunt injuries predominate, excellent trauma survival can be achieved without meeting all trauma centre guidelines for staffing and facilities. Relaxing stringent requirements for the availability of physicians may facilitate surgical recruitment and retention.

Adolescent↗
PubMed1997

Calcitonin gene-related peptide and reperfusion injury.

Calcitonin gene-related peptide is a potent intrinsic vasodilator, can induce prostacyclin release, and may inhibit membrane lipid peroxidation. This study examines the effect of calcitonin gene-related peptide on vessel diameters, capillary perfusion, and contractile function of skeletal muscle after 4 or 5 hours of ischemia and during immediate reperfusion using the rat cremaster muscle model. Forty-two male rats were used; half of these received 0.2 ml of 10(-7) M calcitonin gene-related peptide after 0, 15, and 30 minutes of reperfusion, while the other half received normal saline as a control. By means of intravital videomicroscopy, the diameters of 10 vessels per muscle were measured prior to ischemia and during reperfusion. The fluorescein filling area was determined at 15, 30, and 60 minutes of reperfusion. After 1 hour of reperfusion, muscle function was examined in vitro by quantifying the contractile response to electric field stimulation of the muscles in an organ bath system. There was a significant increase in the diameter of the arterioles, but not the small arteries, at every time point from 10 to 60 minutes of reperfusion. The fluorescein filling area was increased in treated muscles at every time point. Contractile function was not significantly preserved. In light of the ability of calcitonin gene-related peptide to relieve vasospasm and improve capillary perfusion, it may be useful in reducing reperfusion injury in the future.

Animals↗
PubMed1997

Development and implementation of an extremity free-tissue-transfer database.

Rigorous clinical outcomes research requires accurate, complete, and standardized data. No such system is currently being used by reconstructive microsurgeons to evaluate free-tissue-transfer procedures. To facilitate collection of relevant and complete data, the authors propose a standardized format for data collection regarding these procedures. Data are collected via computer entry or scannable forms. The database includes sociodemographic, clinical, health/functional status, patient satisfaction, and resource utilization variables--the necessary components of a well-constructed clinical outcome study. Such studies will give rise to meaningful treatment algorithms for managing reconstructive problems. In addition, widespread use of a standardized databse will facilitate comparisons between practices and allow for meta-analyses. Resultant practice guidelines and microsurgery care maps will ultimately improve patient care and minimize unnecessary costs.

Databases, Factual↗
PubMed1997

Techniques for reducing therapy-interfering behavior in patients with borderline personality disorder. Similarities in four diverse treatment paradigms.

Successful management of patient behaviors that interfere with the process of psychotherapy is essential to treating patients with borderline personality disorder. Provocative patient behaviors that induce a strong negative reaction from the therapist must be attenuated. Strategies for doing so used in four different treatment paradigms--Kernberg's expressive psychotherapy, Linehan's dialectical behavior therapy, Benjamin's interpersonal psychotherapy, and Allen's unified psychotherapy--are examined, and striking similarities are seen. A theoretical model is proposed to explain why the techniques may be effective.

Borderline Personality Disorder↗
PubMed1997

Orthopaedic implant infections: current management strategies.

Orthopaedic joint replacement and spinal stabilisation surgery has provided pain relief and functional improvement for millions. Postoperative infections involving the implanted hardware can have devastating functional, emotional and financial consequences. Implementation of relevant preoperative patient preparation, utilisation of appropriate prophylactic antimicrobials and intraoperative infection control measures have combined to diminish orthopaedic implant infection frequency significantly. Our adeptness at establishing the presence of an implant-related infection with certainty is not as well advanced. Similarly, treatment guidelines, while useful, remain somewhat anecdotal. The pathogenesis, risk factors, diagnosis, management and prevention of hip arthroplasty infection and spinal stabilisation with instrumentation infection are reviewed.

Antibiotic Prophylaxis↗
PubMed1996

Trends in human immunodeficiency virus seroprevalence among injection drug users entering drug treatment centers, United States, 1988-1993.

National unlinked sentinel surveillance data were used to describe trends in prevalent human immunodeficiency virus infection among injection drug users entering drug treatment programs in the United States from 1988 through 1993. During this 6-year period, unlinked testing was performed on 70,882 specimens from injection drug users at 60 sentinel sites. The annual change in seroprevalence was estimated for each site by odds ratios obtained from logistic regression models fit within site-specific age and race/ethnicity subgroups. Overall trends for age and race/ethnicity subgroups across sites were described by summary odds ratios calculated using the inverse variance method. A decrease was observed among younger (age less than 30 years) whites both in areas with high (10% or higher) and low (less than 10%) prevalence, although this decrease was significant only in high-prevalence areas (odds ratio = 0.90, 95% confidence interval 0.81-0.99). Seroprevalence also decreased among older whites in high-prevalence areas, although this decrease was not significant (odds ratio = 0.95, 95% confidence interval 0.89-1.00). Seroprevalence remained stable among all other age and race/ethnicity subgroups. Stable seroprevalence among the dynamic population of injection drug users entering treatment suggests continued transmission among these individuals in both high- and low-prevalence areas of the United States.

Adult↗
PubMed1996

Childhood fever.

Childhood fever is a common symptom, reflective of multiple causes. As the child is often unable to express himself, the physician must rely on parents' observations and the physical examination. The majority of febrile children have non-bacterial upper respiratory tract infection and indiscriminate use of antibiotics is inappropriate, ineffective and leads to drug-resistance such as the emergence of Penicillin-resistant Streptococcus pneumoniae. In this article, we attempt to identify the possible causes of fever by a simple approach using the presence or absence of associated or localising symptoms. Infants less than 3 months constitute a unique group as the fever may be related to perinatal events and as serious bacterial infections can still occur despite unremarkable physical findings. Management of fever needs to take into account the toxicity, immune status and age of the patients as well as the source of the infection. Zealous overprescription of antipyretics needs to be avoided with attention directed to the cause of the fever, the child's capacity to cope with the illness and parental education.

Analgesics, Non-Narcotic↗
PubMed1996

Bronchoscopy in immunocompromised host with pulmonary infiltrates.

Pulmonary complications related to immunosuppression may be secondary to infection, neoplasia, toxic effects of chemotherapy and radiotherapy or the primary disease itself. The diagnostic yield from bronchoscopic studies on immunocompromised hosts (ICH) with pulmonary infiltrates varies widely and the indication and timing for bronchoscopic procedures remain uncertain. We prospectively studied 60 consecutive ICH with pulmonary lesions over a 12-month period. Bronchoscopic studies were performed as soon as pulmonary lesions were detected and within 72 hours of antimicrobial treatment. The patients were divided into two groups: E (40 patients) and L (20 patients) were bronchoscoped on average 1.6 days (SD 0.8) and 16.7 days (SD 10.8) respectively after clinical detection and antimicrobial treatment. A total of 131 bronchoscopic procedures were performed. These included bronchoalveolar lavage 60, bronchoscopic lung biopsy 47, bronchial biopsy 8, brushing 8 and washing 8. Diagnostic yields for bronchoscopically obtained fluid and tissue histology were 45% and 49% respectively. Both complement each other resulting in a higher diagnostic yield of about 70% of the patients in both groups. Procedural complications were minor (13% of cases) and mortality was zero. Infections accounted for approximately two-thirds of the pulmonary lesions. Patients bronchoscoped earlier received less antimicrobial empiric therapy and had shorter hospitalisation. Despite delayed bronchoscopy in ICH in the late group, bronchoscopic results influenced in 85% of patients. However, based on earlier use of appropriate therapy, shorter hospitalisation and decreased costs, we recommend early bronchoscopy when response to empiric treatment has been unsatisfactory.

Adolescent↗