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Biomedical subjects

F Nichols

Publications and source records attributed to F Nichols.

8 recordsLinked to original sources
PubMed2001

Recruiting problem-based learning (PBL) tutors for a PBL-based curriculum: the Flinders University experience.

OBJECTIVES: To examine the contribution made to problem-based learning (PBL) by individual teachers and by departments in years 1 and 2 of a new graduate-entry medical programme (GEMP) with a PBL-based curriculum. METHODS: We compiled a database on all PBL tutoring undertaken in years 1 and 2 during the first 3 years in which the GEMP was delivered. This allowed us to quantify and analyse the contribution made by individuals and by departments. RESULTS: At 3 years following introduction of the GEMP, 136 (25.9%) of the school's 525 staff had trained as PBL tutors and 98 (18.7%) had tutored. Both individuals and departments differed greatly in the amount of time devoted to PBL tutoring. Staff who tutored once tended to tutor again in subsequent years. Compared with staff in clinical departments, those in non-clinical departments (who constituted 12% of the total) made a greater relative contribution though a smaller absolute contribution to tutoring. CONCLUSIONS: These findings prompted us to develop a formula that distributes the PBL tutoring load more evenly across departments. This was successfully introduced in 1999. It recognizes the fact that only a minority of staff will volunteer to become PBL tutors. Strategies that might encourage more staff to tutor are briefly discussed.

Australia↗
PubMed2001

The chemical and physical stability of a 1:1 mixture of propofol and methohexital.

Anesthetic drugs are frequently mixed or coadministered to optimize anesthetic effects while minimizing adverse effects. Methohexital advantages include its low cost and rapid onset, while propofol provides improved airway anesthesia and extremely rapid clearance from the plasma. Therefore, a mixture of these agents might well be superior to either drug given alone. We wished to determine whether a mixture of methohexital and propofol is chemically and physically stable. A 1:1 mixture of propofol 10 mg/ml and methohexital was prepared. At times varying from 0 to 48 hours, mixtures with an internal standard of thymol kept at room temperature were thrice extracted with a 2:1 v/v mixture of diethyl ether:pentane, dried under nitrogen, and treated overnight with bis-trimethylsilyl-trifluoroacetamide. The resultant derivatives were transferred to microsample vials and analyzed by GC-MS. Drug stability was quantified by electronic integration of peak areas representing characteristic ions for each drug. For each sample, the peak area of the methohexital ion (m/z 239) or propofol ion (m/z 235) relative to the corresponding thymol ion (m/z 207) served as an index of the concentration of the drug in the sample. At times varying from 0 to 48 hours, mixtures without thymol were used to determine mean droplet size of the particles. This was accomplished using both an Accusizer and a Nicomp 370 Particle Sizer. One way ANOVA tested for significant changes in drug concentrations and mean particle size as a function of time. There was no significant breakdown of propofol or methohexital when combined in a 1:1 mixture and allowed to stand for 48 hours, nor was there an increase in particle size suggestive of emulsion instability. We concluded that a 1:1 mixture of propofol and methohexital was stable up to 48 hours after mixing.

Analysis of Variance↗
PubMed1998

Subcutaneous administration of midazolam: a comparison of the Bioject jet injector with the conventional syringe and needle.

PURPOSE: The purpose of this study was to compare jet injection to a syringe and needle in terms of the difference in discomfort and pharmacokinetics after the subcutaneous administration of midazolam. PATIENTS AND METHODS: Using a prospective, randomized, double-blinded study design, 14 subjects were administered midazolam on two separate occasions (at least 2 weeks apart). The subjects were randomly distributed into two groups: syringe and needle (saline)/jet injector (midazolam) or syringe and needle (midazolam)/jet injector (saline). The subjects were randomly assigned to receive either EMLA (eutectic mixture of local anesthetics) or a placebo at the injection site for the first administration and the other topical agent on the second visit. Each subject received one subcutaneous injection in the deltoid region per arm per day. Each injection contained the same volume of solution. Subjects completed visual analog scale (VAS) questionnaires assessing the discomfort of the injection. Blood samples were taken at specified intervals over 2 hours for determination of midazolam levels. RESULTS: The discomfort associated with the injection was less with the Biojector 2000 (Bioject Inc, Portland, OR) although this was not statistically significant. However, persistent discomfort was significantly greater at the needle site. The mean peak plasma level of midazolam was achieved more rapidly with the Biojector 2000 than with the syringe and needle (P < .05). However, the peak plasma level after jet injection or injection with a syringe and needle was not statistically different. CONCLUSION: The results of the study show that the Biojector 2000 is a needle-free injection system that can be used for the administration of a premedicant before induction of anesthesia. It has several advantages, including the potential reduction of anxiety associated with the "fear of needles" and occupational injuries.

Adolescent↗
PubMed1998

Relationship between hydroxy fatty acids and prostaglandin E2 in gingival tissue.

Bacterial hydroxy fatty acids and alpha-hydroxy fatty acids have been demonstrated in complex lipid extracts of subgingival plaque and gingival tissue. However, little is known about the relationship between these hydroxy fatty acids in plaque and gingival tissues or the significance of these complex lipids in promoting inflammatory periodontal disease. The present study determined the percentages of ester-linked and amide-linked hydroxy fatty acids in complex lipids recovered from plaque and gingival tissue samples and the relationship between bacterial hydroxy fatty acids and alpha-hydroxy fatty acids in the lipid extracts. To evaluate a potential role for these hydroxy fatty acids in inflammatory periodontal disease, gingival tissue samples were examined for a relationship between prostaglandin E2 (PGE2) and hydroxy fatty acids recovered in gingival lipid. This investigation demonstrated that alpha-hydroxy fatty acids are only ester linked in plaque lipids but are largely amide linked in gingival tissue lipids. Furthermore, the level of alpha-hydroxy fatty acid in gingival lipid is directly related to the level of the bacterial hydroxy fatty acid 3-OH iso-branched C17:0 (3-OH iC17:0) in the same lipid extract. However, the relationship between hydroxy fatty acids in gingival lipids does not parallel the fatty acid relationship observed in plaque lipids. Finally, alpha-hydroxy fatty acid levels in gingival tissue lipids correlate directly with the recovery of PGE2 in the same tissue samples. These results demonstrate that alpha-hydroxy fatty acid levels in gingival lipids are directly related to both 3-OH iC17:0 bacterial lipid levels and PGE2 levels. These results indicate that in periodontal tissues there are unusual host-parasite interactions involving penetration of bacterial lipid in association with an altered gingival lipid metabolism and prostaglandin synthesis.

Amides↗
PubMed1994

Host responses in patients with generalized refractory periodontitis.

Although patients with refractory periodontitis have been widely reported, no clear biologic profile of these patients has been noted. The purpose of the present study was to evaluate host responsiveness of a well-defined group of refractory periodontitis patients by determining the effect of a lipopolysaccharide (LPS) challenge on monocyte surface receptor density and on the release of inflammatory mediators. Venous blood was obtained from 7 refractory periodontitis, 8 stable periodontal maintenance, and 8 gingivitis patients with no evidence of periodontitis. Mononuclear cells were cultured in either control media or media treated with Actinobacillus actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), or Salmonella typhimurium (S. typh) LPS. At 0 and 24 hours supernatants were assayed for prostaglandin-E2 (PGE2) and interleukin-1 beta (Il-1 beta) release by ELISA. Using flow cytometry the density of specific monocyte surface receptors were assayed with Mo3e and LeuM3 monoclonal antibodies (mAb); T-cell CD4/CD8 ratios were assayed with OKT-3, OKT-4, and OKT-8 mAb. After 24 hours incubation with Pg or S. typh LPS, the upregulation of the Mo3e receptor was significantly decreased for refractory periodontitis patients (P < 0.05) when compared to gingivitis and to stable maintenance patients. In refractory periodontitis patients the T-cell CD4/CD8 ratio was decreased. Upon stimulation with Pg or S. typh LPS, monocytes from stable maintenance and refractory periodontitis patients released more Il-1 beta (P < 0.05) and PGE2 (P = 0.13 and 0.15) than monocytes from gingivitis subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

The use of transcranial ultrasonography to predict stroke in sickle cell disease.

BACKGROUND: Stroke, especially cerebral infarction, is a major cause of morbidity and mortality in children with sickle cell disease. Primary prevention of stroke by transfusion therapy may be feasible if there is a way to identify the patients at greatest risk. Transcranial Doppler ultrasonography can measure flow velocity in the large intracranial arteries. The narrowing of these arteries, which leads to cerebral infarction, is characterized by an increased velocity of flow. METHODS: Using transcranial Doppler ultrasonography, we prospectively measured the velocity of cerebral blood flow in children and young adults being followed because of sickle cell disease. The results were classified as either normal or abnormal on the basis of the highest velocity of flow in the middle cerebral artery. Abnormal velocity was defined as a flow greater than or equal to 170 cm per second, a definition determined by post hoc analysis to maximize the predictive success of the test. The end point was a clinically apparent first cerebral infarction. RESULTS: Two hundred eighty-three transcranial ultrasound examinations were performed in 190 patients with sickle cell disease (age at entry, 3 to 18 years). After an average follow-up of 29 months, cerebral infarction was diagnosed in seven patients. In 23 patients the results of the ultrasound examinations were abnormal, and in 167 patients they were normal. The clinical and hematologic characteristics of the two groups were similar, but six of the seven strokes occurred among the 23 patients with abnormal ultrasound results (P less than 0.00001 by Fisher's exact test). In this group, the relative risk of stroke was 44 (95 percent confidence interval, 5.5 to 346). CONCLUSIONS: Transcranial ultrasonography can identify the children with sickle cell disease who are at highest risk for cerebral infarction. Periodic ultrasound examinations and the selective use of transfusion therapy could make the primary prevention of stroke an achievable goal.

Adolescent↗