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Biomedical subjects

N Frost

Publications and source records attributed to N Frost.

14 recordsLinked to original sources
PubMed1993

Integration of 3-D medical imaging and rapid prototyping to create stereolithographic models.

This paper describes current research into the creation of solid models which replicate anatomical structures using rapid prototyping techniques. Stereolithography is particularly efficient in the production of highly-complex structures. This technique was applied to the fabrication of a plastic model of a human skull. A geometric definition of the object was obtained by transferring the three-dimensional medical image volume (x-ray CT) and processing the data on a computer graphics workstation. A 3-D biomedical visualisation software package (ANALYZETM) was used to perform segmentation of structures. A 3-D triangular-mesh representation of the selected structure was calculated and converted to a format suitable for processing and construction using stereolithography (SLA). Improvements in the quality of the anatomical model produced will result from improved data processing techniques. Future work is proposed to investigate the influence of imaging parameters and data processing techniques on the resultant plastic models.

Humans↗
PubMed1993

Laparoscopic versus clinical diagnosis of acute pelvic inflammatory disease.

The purpose of this study was to evaluate the accuracy of clinical diagnosis of acute pelvic inflammatory disease (PID). Data were obtained on 176 consecutive women admitted to St. Elizabeth Hospital Medical Center with a clinical diagnosis of PID. All underwent diagnostic laparoscopy. PID was established laparoscopically in 134 (76.1%) of the patients. Statistical tests for significant associations between PID and each of 21 clinical indicators of the disease were conducted using the chi 2 and Mann-Whitney tests. Stepwise logistic regression was performed on those variables whose univariate tests of significant association with PID resulted in P values < 0.20. An optimal set of PID indicators consisted of adnexal tenderness, lower abdominal pain of < one week's duration and an elevated white blood cell count. Use of these indicators resulted in a test with an estimated sensitivity and specificity of 86.6% and 45.7%, respectively. Estimated predictive values for positive and negative test results were 0.84 and 0.52, respectively. These results confirm the fact that laparoscopy is the definitive diagnostic modality in PID.

Acute Disease↗
PubMed1985

Anti-herpes simplex virus and cytostatic activity of some new 5-substituted 1-(4-hydroxybutyl)-and 1-(2-hydroxyethoxymethyl) uracil nucleoside analogues.

Two series of 5-substituted acyclic uracil nucleoside analogues (5-X-acyclo-U) were evaluated for their inhibitory effects against three herpes simplex virus type 1 (HSV-1) strains and one type 2 (HSV-2) strain in a plaque inhibition assay on human embryonic lung fibroblast (HELF) cell cultures as well as for their ability to inhibit the proliferation of baby hamster kidney cells in suspension (BHK-S) culture. Acyclovir [9-(2-hydroxyethoxymethyl)guanine; ACV] and (S)-9-(2,3-dihydroxypropyl)adenine [(S)-DHPA] were used as reference compounds. Only two derivatives, 1-(4-hydroxybutyl)-5-(2,2-dibromovinyl)uracil (Br2V-HBU) and 1-(2-hydroxyethoxymethyl)-5-(2,2-dibromovinyl)-uracil (Br2V-HEMU) proved active, but only at high concentrations (57-350 mumol/l) and without selectivity of anti-herpes activity, whereas ACV showed strong inhibition of HSV-1 and HSV-2 and a low cytostatic effect on BHK-S cells (50% inhibitory concentrations are 0.25-0.73, 2.1, and 240 mumol/l for HSV-1, HSV-2, and BHK-S, respectively), demonstrating a high antiherpes selectivity. In contrast, all other 5-X acyclo-U analogues [X = methyl, ethyl, propyl, butyl, vinyl, and 2-bromovinyl; acyclo = 1-(4-hydroxybutyl) and 1-(2-hydroxyethoxymethyl)] as well as the reference compound (S)-DHPA were inactive at concentrations up to 0.5-1 mmol/l. Some structure to activity relationships of acyclic pyrimidine and purine nucleoside analogues are discussed.

Acyclovir↗
PubMed1980

Effects of nitrous oxide on systolic time intervals.

The effects of inhalation of oxygen, nitrous oxide/oxygen and nitrous oxide/nitrogen/oxygen on systolic time intervals (PEP (pre-ejection period) and LVET (left ventricular ejection time) were investigated in eight healthy persons. Nitrous oxide 40%, administered with oxygen or oxygen/nitrogen, prolonged PEP significantly by 25% and 22%, respectively. Inhalation of oxygen also prolonged PEP but to a significantly minor degree. LVET, heart rate and MAP were unchanged during the experiments. Derivatives from the systolic time intervals, i.e. PEP/LVET, I/PEP2 and ejection fraction changed significantly in the nitrous oxide groups. It is concluded that nitrous oxide depresses cardiac performance, to some degree, even when administered at a rather low concentration.

Adult↗
PubMed1975

A comparison between measured and calculated changes in the lung function after operation for pulmonary cancer.

Eighteen patients operated on for pulmonary cancer, the procedure varying from the removal of two segments to pneumonectomy, were subjected to measurement of the spirometric values VC, FEV1, FRC and RV preoperatively and 2-3 months postoperatively. The possibility of predicting the postoperative values from the number of segments removed was studied, partly with standard percentages (5.26%) per segment (method I), and partly with a percentage per segment in the affected area, calculated from the preoperative regional lung function tests using 133xenon. This latter test was carried out with a mobile apparatus using four detectors with tubular colimators and from the anterior surface of the thorax. Both methods of calculation gave, for the material as a whole, good agreement between the postoperative (measured) and the calculated values. However, with regard to certain patients, the regional lung function tests gave important information on preoperative reduced function in the affected area. In these patients, method No. II was by far the best for prediction of the postoperative values.

Aged↗