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Biomedical subjects

D C Brown

Publications and source records attributed to D C Brown.

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

A reconstructed computerized tomographic comparison of Ni-Ti rotary GT files versus traditional instruments in canals shaped by novice operators.

AIM: The aim of this study was to compare the effects of preparation with conventional stainless steel Flexofiles and Gates Glidden burs versus nickel-titanium GT rotary files in the shaping of mesial root canals of extracted mandibular molars. METHODOLOGY: A total of 54 canals from 27 mesial roots of mandibular molar teeth were prepared using one of two methods by novice dental students. One canal in each root was prepared by a crown-down approach. utilizing stainless steel Flexofiles and Gates Glidden burs. The other canal was prepared using nickel-titanium GT rotary files in a crown-down fashion as recommended by the manufacturer. Preoperative CT scans of each root were recorded and 50 canal specimens were available for postoperative comparisons. Following canal shaping, postoperative scans were superimposed on the original images. Changes in canal area, canal transportation and thickness of remaining root structure at strategic levels of the root were analyzed. The time taken for each method was also noted. RESULTS: At the coronal and mid-root coronal one-third sections, the rotary GT files produced a significantly smaller postoperative canal area (P < 0.05). In the mid-root sections there was significantly less transportation of the root canal toward the furcation, and less thinning of the root structure with GT files compared to the stainless steel files (P < 0.05). Overall, there was greater conservation of structure coronally and more adequate shape in the mid-root level. The GT rotary technique was significantly faster than the stainless steel hand-held file technique (P < 0.0001). Two GT instruments fractured during the study. CONCLUSIONS: Under the conditions of this study, novice dental students were able to prepare curved root canals with Ni-Ti GT rotary files with less transportation and greater conservation of tooth structure, compared to canals prepared with hand instruments. The rotary technique was significantly faster.

Dental High-Speed Technique↗
PubMed2001

Growth hormone therapy and growth in children with Noonan's syndrome: results of 3 years' follow-up.

Growth data from the first 3 yr of a multicenter study examining the efficacy and safety of recombinant human GH [rhGH; 4 IU (1.3 mg)/m(2).day, sc] in children with Noonan's syndrome (NS) are reported for 23 subjects. Sixteen male and seven female patients (age, 9.3 +/- 2.6 yr at onset of GH therapy, mean +/- SD; range, 4.8-13.7) were each assessed at 1, 2, and 3 yr after starting treatment. Comparisons were made with a group of eight subjects (six males and two females, age, 9.0 +/- 4.1 yr; range, 4.1-14.8) with NS, not treated with rhGH, measured over the same period. All treated subjects underwent annual cardiac assessment. Height SD score increased from -2.7 +/- 0.4 at the start of GH therapy to -1.9 +/- 0.9 3 yr later (P < 0.001, two-tailed t test). This corresponded to an increase in height from 116.1 +/- 13.2 to 137.3 +/- 14.0 cm. Height velocity increased from 4.4 +/- 1.7 cm/yr in the year before treatment to 8.4 +/- 1.7 (P < 0.001), 6.2 +/- 1.7 (P < 0.001), and 5.8 +/- 1.8 (P = 0.01, two-tailed t test compared with baseline) during the first, second, and third years of GH treatment, respectively. Height acceleration was not significant during the second or third years when pubertal subjects were excluded. The comparison group showed an increase in height from 116.0 +/- 19.8 to 131.9 +/- 21.1 cm over the 3 yr (height SD score, -2.7 +/- 0.6 to -2.4 +/- 0.7, P = 0.3). None of the 23 children developed hypertrophic cardiomyopathy during GH treatment. The increase in growth rate in NS resulting from 1 yr of GH therapy seems to be maintained during the second year, although height velocity shows a less significant increase over pretherapy values. Possible abnormal anabolic effects of rhGH on myocardial thickness were not confirmed, and no treated patient developed features of hypertrophic cardiomyopathy.

Adolescent↗
PubMed2001

Effect of centrally administered opioid receptor agonists on CSF and plasma oxytocin concentrations in dogs.

OBJECTIVE: To measure oxytocin concentrations in blood and CSF following central administration of opioid agonists in dogs. ANIMALS: 5 male dogs. PROCEDURE: In a crossover design, CSF and blood were collected immediately before and 15 and 30 minutes after cisternal administration of D-Ala2, MePhe4, Gly-ol-enkephalin (DAMGO, a mu-receptor agonist); D-Pen, pCl-Phe4, D-Pen5-enkephalin (a delta-receptor agonist); U50488H (a kappa-receptor agonist); morphine; and saline (0.9% NaCl) solution. RESULTS: Plasma oxytocin concentration was significantly increased 15 minutes after administration of DAMGO and 30 minutes after administration of U50488H, compared with concentrations obtained after administration of saline solution. Concentration of oxytocin in CSF was significantly decreased 30 minutes after administration of U50488H, compared with concentration after administration of saline solution. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that in male dogs, activation of centrally located mu and kappa receptors elicits an overall excitatory effect on neurons that regulate peripheral release of oxytocin, whereas activation of centrally located kappa receptors elicits an overall inhibitory effect on neurons that regulate central release. These results are in contrast to those reported for other species, in which opioids have a pronounced inhibitory effect on release of oxytocin from the neurohypophysis.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed2000

Gastrointestinal emergencies.

The animal with a surgical gastrointestinal emergency usually requires a rapid, thorough physical examination with concurrent resuscitation. As the diagnosis is being made, the animal must be made as stable as possible before undergoing general anesthesia. During surgery, there must be a critical evaluation of gastrointestinal viability and the use of precise technical skills to achieve the best outcome. Adept postoperative management, including careful monitoring and an index of suspicion for potential complications, is vital.

Animals↗
PubMed2000

A practical approach to hemoperitoneum in the dog and cat.

Hemoperitoneum can occur in animals of any age and can result from many different disease processes. Neoplastic and traumatic conditions are the most common causes. Many of these patients present with hemodynamic instability but stabilize with rational intravenous fluid therapy and abdominal counterpressure. Surgical exploration of the abdomen is indicated in many situations. Surgical therapy is aimed at resection or control of the bleeding focus, removal of any devitalized tissue, and biopsy of additional sites of suspicion. Optimal treatment for all patients with hemoperitoneum frequently requires advanced critical care, anesthesia, and surgical techniques. Finally, the treatment outcome is variable and dependent on the underlying cause and its severity.

Animals↗
PubMed1999

All-trans retinoic acid regulates adhesion mechanism and transmigration of the acute promyelocytic leukaemia cell line NB-4 under physiologic flow.

The success of all-trans retinoic acid (ATRA) in the therapy of acute promyelocytic leukaemia (APL) has received increased attention. Unfortunately, life-threatening multiorgan failure commonly occurs, i.e. retinoic acid syndrome, and is thought to be the result of organ infiltration by leukaemic cells. We hypothesized that ATRA-induced differentiation of APL cells leads to adhesion receptor alterations responsible for leucocyte extravasation from the blood into tissue. Changes in adhesive properties of the APL cell line NB-4 in response to ATRA were investigated using a parallel plate flow chamber under conditions that recapitulate physiologic flow conditions. Untreated NB-4 cells initially tether and roll on activated human umbilical vein endothelial cell monolayers using a combination of E-selectin, P-selectin and alpha4 integrin. After ATRA treatment, > 80% of initial NB-4 cell attachment to endothelial cells was E-selectin dependent. Stable arrest (firm adherence) of NB-4 cells on activated endothelium was also altered by ATRA treatment. Untreated NB-4 cells used alpha4 integrin to arrest on endothelium, but beta2 integrin dependent arrest was induced by ATRA. With the acquisition of beta2 integrin function, ATRA-treated cells acquired the ability to transmigrate through activated endothelium. Thus, ATRA dramatically altered the adhesion phenotype on NB-4 cells: ATRA induced rolling largely attributable to E-selectin, abrogated alpha4 integrin dependent rolling, and promoted acquisition of beta2 integrin dependent firm adherence and transmigration. These findings represent novel cellular and differentiation effects of ATRA, and, to our knowledge, are the first demonstration that a therapeutic agent differentially regulates alpha4 and beta2 integrin on the same leucocyte.

Cell Adhesion↗
PubMed1999

A survey of biomedical scientists and consultant pathologists involved in the cervical screening programme.

The past decade has seen a transformation in the National Health Service Cervical Screening Programme (NHSCSP) largely driven by responses to various screening scandals. Independent inquiries into these laboratory failures have identified a number of contributing factors. The aim of this postal survey was to determine how widespread these factors are throughout screening laboratories in England. The results indicate that issues around recruitment and retention of staff, the training of pathologists and low morale appear to be widespread. However, the results do not indicate a widespread breakdown in working relationships between consultants and biomedical scientists, although there is room for improvement in their relationships with hospital management. Finally, there seem to be mixed messages about the commitment of consultants to the screening programme.

Burnout, Professional↗
PubMed1999

Use of propofol to manage seizure activity after surgical treatment of portosystemic shunts.

The anaesthetic agent propofol has anticonvulsant properties and has been used in the treatment of refractory status epilepticus in human medicine. This report describes the use of propofol in four cats and one dog with naturally occurring seizures following surgical attenuation of single extrahepatic portosystemic shunts. Two of the animals had seizures that were unresponsive to other anticonvulsants. Subanaesthetic doses of intravenous propofol (1.0 to 3.5 mg/kg boluses and 0.01 to 0.25 mg/kg/minute continuous rate infusions) were used to control the seizures in all animals. However, a good neurological outcome was achieved in only two of the five cases, which is similar to the situation in previous reports.

Animals↗
PubMed1999

Measures for decreasing inpatient stay in childhood asthma.

Traditionally, studies of asthma have concentrated on interventions that were mainly pharmaceutical and outcomes that were usually based on pulmonary function testing. More recently, there has been increasing emphasis on organisational procedures that can enhance the delivery of effective care, and outcomes based more on the clinical than the physiological. Minimum length of stay is targeted as one outcome of benefit for patients and their families. The methods of decreasing hospital stay for asthmatic children which have been proposed and studied are reviewed.

Asthma↗
PubMed1998

Comparison of effects of elective tenectomy or onychectomy in cats.

OBJECTIVE: To compare short- and long-term complications after tenectomy of the deep digital flexor tendons or onychectomy and owner satisfaction with these surgical procedures. DESIGN: Prospective cohort study. ANIMALS: 20 cats undergoing tenectomy and 18 cats undergoing onychectomy. PROCEDURE: Cats undergoing tenectomy or onychectomy were monitored for a minimum of 5 months to enable comparison of type and frequency of complications. Owner satisfaction was also assessed. RESULTS: Cats undergoing tenectomy had significantly lower pain scores 24 hours after surgery, compared with those undergoing onychectomy. Type and frequency of other complications did not differ between procedures. Owners appeared to be less satisfied with the tenectomy procedure than with the onychectomy procedure, although scores for satisfaction with each procedure were not significantly different. CLINICAL IMPLICATIONS: Owners should be aware of the high complication rate for both procedures and of the need for constant trimming of claws of cats that have undergone tenectomy.

Animals↗
PubMed1998

Staar Collamer intraocular lens: clinical results from the phase I FDA core study.

PURPOSE: To assess the early postoperative efficacy and safety of the Staar Collamer intraocular lens (IOL) in small incision cataract surgery. SETTING: Six private ophthalmology practices geographically distributed throughout the United States. METHODS: One hundred twenty-five patients with a mean age of 72.1 years were enrolled in the U.S. Food and Drug Administration (FDA) Phase 1 clinical study of the Staar Collamer IOL after having cataract removal by phacoemulsification. Of these, 107 completed 4 to 6 months of follow-up. RESULTS: At 4 to 6 months postoperatively, 97.1% of patients achieved 20/40 or better corrected visual acuity; 100% of patients without pre-existing pathology (best case) achieved the same result; both results were better than FDA grid values. No persistent sight-threatening complications were reported. Through 6 months, 4.7% of patients required a neodymium:YAG capsulotomy. No IOL dislocations or removals were reported. CONCLUSION: Results indicate that the Collamer material is safe and effective for platehaptic IOLs used in small incision cataract surgery.

Aged↗