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Biomedical subjects

J Pfitzner

Publications and source records attributed to J Pfitzner.

At least 37 records · Page 2Linked to original sources
PubMed2000

Videoscopic lung volume reduction surgery in an Australian public teaching hospital.

BACKGROUND: Lung volume reduction surgery (LVRS) has been a frequent literature topic in emphysema management recently. Opinions differ in regard to usefulness, efficacy, and selection criteria. AIMS: To present the results of our first 55 bilateral videoscopically resected group, with follow-up of up to three years, and to present some of the local methodology problems faced. METHODS: Thirty-nine men and 16 women, age range 40-77, had either upper lobe (42), mixed (two), or lower lobe (11) resections without buttressing (except for unilateral buttressing in several of the latter patients as part of an intrapatient comparison trial) according to their pattern of emphysema determined by CT and perfusion scanning. RESULTS: Thirty day mortality was 5.5%. Follow-up pulmonary function is available for 44 patients, and demonstrates a mean 51% improvement in FEV1, and significant improvement in FVC, PaO2, dyspnoea indices and walking distance, with a reduction in mean RV, TLC, PaCO2. FEV1 improvement is maintained above baseline at three years. Lower lobe surgery outcomes are at least as good as their upper lobe counterparts. CONCLUSIONS: Outcomes confirm improvements reported elsewhere, and suggest that videoscopic resection may provide worthwhile benefit to lower lobe patterns of emphysema. Other managment issues are discussed.

Activities of Daily Living↗
PubMed1999

Genetic and environmental contributions to size, color, shape, and other characteristics of melanocytic naevi in a sample of adolescent twins.

The presence of melanocytic naevi is the strongest known risk factor for malignant melanoma. We have developed a computer imaging system with which it is possible to make quantitative measures of the size, color, and shape of pigmented lesions. The objective of this study was to examine the genetic and environmental contributions to these characteristics of naevi as measured by computer image analysis in a sample of adolescent twins. We captured video images of the 5 most atypical pigmented skin lesions (i.e., the largest, darkest, or most irregularly shaped) on each individual from 322 Australian adolescent twin pairs. Features extracted by computer image analysis for each lesion included color, size, symmetry, elongation, boundary irregularity, and edge distinctness. We found major genetic influences on the color and size of lesions accounting for between 40 and 80% of total variance. There were significant components of shared environmental influence (22-45% of total variance) for the color variables, with sun exposure the most obvious explanation. Differences between individuals in naevus color and size are largely genetic in origin although there are significant environmental contributions to color as well.

Adolescent↗
PubMed1999

Bronchial anatomy and single-lung ventilation in the pig.

PURPOSE: To explore why two pigs died in the course of a study in which a double-lumen tube (DLT) was used to achieve single-lung ventilation, the bronchial anatomy of all six pigs involved in the study was examined at autopsy. METHODS: Autopsy involved examination of the lungs in situ and subsequent dissection of the lung tissue from the lobular bronchi. RESULTS: All six pigs were found to have an apical lobe (or lobular) bronchus arising from the trachea. In three it was on the right, as is usual in pigs, and in three, including the two that died, it was on the left. The mainstem bronchi to both lungs were short in all pigs, with major segmental bronchi arising just distal to the carina. CONCLUSION: The bronchial anatomy of the pig is such that the inflated cuffs of commercially available DLTs may cause partial or complete obstruction of the apical bronchi of one or both lungs, regardless of the side of the tracheal bronchus. The transmission of the resulting breath sounds across the narrow pig thorax can make auscultation unhelpful in assisting with optimal tube placement.

Animals↗
PubMed1999

A randomized controlled trial to determine the effects of humidified carbon dioxide insufflation during thoracoscopy.

BACKGROUND: The humidification of gas insufflated during laparoscopy can reduce the degree of postoperative hypothermia and may result in less peritoneal reaction and less postoperative pain. The present study was designed to determine whether the beneficial effects of humidified gas insufflation also applied to thoracoscopy. METHODS: Six pigs were each studied on three separate occasions with insufflation into the right thoracic cavity of either humidified gas, standard dry gas, or with no insufflation (control procedure). Core body temperature was recorded every 15 min, and biopsies of the parietal pleura were taken at the end of each study for electron microscopy. RESULTS: Humidification of insufflated gas significantly minimized the fall in core temperature during the procedure. Electron microscopy showed that dry gas insufflation resulted in greater structural injury to the pleura than humidified gas insufflation. CONCLUSIONS: The potential benefits of humidifying insufflation gas during thoracoscopy warrant its evaluation in the clinical setting.

Analysis of Variance↗
PubMed1999

Gas movement in the nonventilated lung at the onset of single-lung ventilation for video-assisted thoracoscopy.

To assess the potential for atmospheric nitrogen to enter the nonventilated lung following the initiation of single-lung ventilation, the nonventilated lung of 10 patients undergoing video-assisted thoracoscopy was connected to the air in a water-filled spirometer, and gas movement out of and back into the lung was measured. Airway pressure from both lungs and pleural pressure from the nonventilated side were also measured. With each breath of positive-pressure ventilation to the ventilated lung prior to the thoracic cavity being opened to the atmosphere, the pressure transmitted to the opposite hemithorax generated a mean (range) tidal movement of gas in the nonventilated lung of 134 (65-265) ml. In addition, ongoing gas exchange resulted in a progressive influx of gas from the spirometer over the 110-120 s measurement period of a mean (range) volume of 155 (70-320) ml. This easily preventable influx of atmospheric nitrogen could, in theory, predispose to arterial desaturation and to delayed lung collapse after the parietal pleura is opened.

Adolescent↗
PubMed1999

Ambient pressure oxygen reservoir apparatus for use during one-lung anaesthesia.

An ambient pressure oxygen reservoir bag apparatus for connecting to the nonventilated lung as soon as single-lung ventilation is initiated is described. The theoretical benefits are the facilitation of collapse of the lung on the side of surgery and a reduced likelihood of arterial desaturation. Although these main benefits are yet to be proven, the authors believe that the weight of theoretical argument and practical observation serves to justify the use of the apparatus while the outcome of suitably designed clinical trials is awaited. It can be used for all one-lung anaesthetics and is especially recommended for thoracoscopic surgery, where temporary re-expansion of the nonventilated lung is either counter-productive or contraindicated, and where there is a possibility that lung collapse may be delayed.

Drug Delivery Systems↗
PubMed1998

Quantity and structure of surfactant proteins vary among patients with alveolar proteinosis.

Alveolar proteinosis (AP) is an idiopathic condition characterized by excess alveolar surfactant. Although the surfactant proteins (SP) are known to be aberrant, little is known of their variation between patients or their abundance relative to the lipids. We have examined surfactant composition in lavage fluid from 16 normal subjects and 13 patients with AP, one of whom was lavaged on 11 occasions over approximately 13 mo. In this patient we have examined composition on each occasion and in each sequential lavage aliquot. Composition was constant between right and left lung, but it differed markedly between patients. The cholesterol/disaturated phospholipid ratios (CHOL/DSP) were invariably elevated, on average by approximately 7-fold, whereas the SP-A/DSP and SP-B/DSP ratios were generally elevated, in some cases by as much as approximately 40- and approximately 100-fold, respectively. Although AP lavage generally contained more non-thiol-dependent SP-A aggregates and low Mr isoforms, the two-dimensional immunochemical staining patterns varied between patients and right and left lung. In the patient lavaged on multiple occasions, the SP-A/DSP and SP-B/DSP ratios progressively decreased as the patient's condition resolved. Because the SP-B/SP-A ratio was normal in all cases, we suggest that structural changes to the proteins occurred secondarily and that caution must be used in comparing functional data derived using SP-A obtained from patients with AP.

Adolescent↗
PubMed1997

Cerivastatin: pharmacology of a novel synthetic and highly active HMG-CoA reductase inhibitor.

The pyridine derivative cerivastatin is a new entirely synthetic and enantiomerically pure inhibitor of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase. As a sodium salt cerivastatin is present in the active, open ring form. Cerivastatin inhibited the membrane-bound (non-solubilized) HMG-CoA reductase of the native microsomal fraction isolated from rat liver with a Ki value of 1.3 x 10(-9) M. The reference compound lovastatin was 100-fold less potent and exhibited a Ki value of 150 x 10(-9) M. Cerivastatin inhibited the cholesterol synthesis in the human hepatoma cell line HepG2 cells with a similar IC50 value of 1.0 x 10(-9) M. In vivo studies reflected its high in vitro activity. In both rats and dogs, cerivastatin inhibited the hepatic [14C]cholesterol synthesis from [14C]acetate with an oral ED50 value of 0.002 mg/kg body weight, while lovastatin exhibited an oral ED50 value of 0.3 mg/kg in rats, showing again the ratio of 100 or more between cerivastatin and lovastatin. In the small intestine and testes, cerivastatin was at least 50-fold less active with oral ED50 values higher than 0.1 mg/kg, which is indicative for a high liver selectivity of cerivastatin. In cholestyramine-primed dogs cerivastatin dose-dependently lowered the serum cholesterol concentrations by up to 59% with 0.1 mg/kg after 20 days. Interestingly, the serum triglycerides were markedly reduced by 53 and 76% with 0.03 and 0.1 mg/kg, respectively. In normal chow fed dogs the low density lipoprotein (LDL) concentrations were reduced by up to 75% after 0.1 mg cerivastatin/kg. The ratio of HDL/LDL increased by 81% compared with a change of only 14% in the placebo treated control group. The antiatherogenic effect of cerivastatin was shown in rabbits fed a diet enriched with 0.2% cholesterol. After 9 weeks on diet 0.1 mg cerivastatin/kg decreased the accumulation of cholesterol ester in the arterial tissue by 73%. In summary, these data as compared to published data on other HMG-CoA reductase inhibitors demonstrate cerivastatin to be the most active compound in this class. Vastatins used in therapy are effective in mg doses, while cerivastatin offers a new low dose therapy in the microg range.

Administration, Oral↗
PubMed1996

Reliability of computer image analysis of pigmented skin lesions of Australian adolescents.

BACKGROUND: The diagnosis of melanomas at an early stage is associated with improved survival, so the recognition of changes in pigmented skin lesions over time is important. We have developed a computer imaging system with the aim of assisting clinicians in differentiating early melanomas from benign pigmented skin lesions. The objective of this study was to investigate the system's reliability over time in measuring diagnostic characteristics of pigmented skin lesions, including their color, size, shape, and distinctness of boundary. METHODS: We captured video images of 5 lesions, all larger than 2 mm in greatest dimension, on each of 66 Australian adolescents on 2 occasions approximately 1 month apart. Features extracted by computer image analysis included area, perimeter, and regularity of outline of the lesions, the mean and standard deviation of reflectance at red, green, and blue wavelengths, and the mean and standard deviation of the gradients of red, green, and blue reflectance at the lesion boundary. RESULTS: All measurements showed moderate to high reliability (intraclass correlation coefficients 0.66-0.94), except for the standard deviations of the color gradients, whose reliability improved to moderate levels (0.68-0.71) when the mean of 5 lesions was considered. For most outcomes, reasonable within subject reliability was achieved when five lesions per subject were measured. CONCLUSIONS: These results, in combination with previous work demonstrating the reasonable ability of this computer imaging system to discriminate between malignant melanomas and other pigmented lesions, indicates that the system has the potential to become a useful tool for clinicians in following people with pigmented lesions over time to detect early malignant changes.

Adolescent↗
PubMed1994

Post-laminectomy cerebrospinal fluid fistula treated with epidural blood patch.

UNLABELLED: OBJECTIVES AND SUMMARY OF BACKGROUND DATA: Cerebrospinal fluid fistula after spinal surgery is associated with a definite risk of meningitis or discitis, and as a result, early active intervention usually is recommended. METHODS AND RESULTS: This report describes the successful use of an epidural blood patch after a more conventional intervention--namely, surgical re-exploration--had failed to control a postoperative cerebrospinal fluid leak. CONCLUSIONS: The techniques involved in performing a blood patch after spinal surgery may well differ from those usually recommended in the management of spinal headache resulting from other causes of dural puncture.

Aged↗
PubMed1994

Computer image analysis in the diagnosis of melanoma.

BACKGROUND: It is often difficult to differentiate early melanoma from benign pigmented lesions of similar clinical appearance. OBJECTIVE: Our purpose was to develop a computer image analysis system that has the potential for use as an adjunct to the clinical distinction of melanoma from less serious pigmented lesions. METHODS: The system, consisting of a hand-held device incorporating a color video camera and color frame grabber mounted in a microcomputer, was used in a pigmented lesion clinic. Analysis software extracted features relevant to the size, color, shape, and boundary of each lesion, and these features were correlated with clinical and histologic characteristics on which standard diagnoses of skin tumors are based. For discriminant analysis based on image analysis measurements, equal prior probabilities were assigned to two specified diagnostic groups, namely melanoma and "other pigmented lesions," most of which were melanocytic nevi. RESULTS: In a 20-month period, video images of 164 unselected pigmented lesions for which complete diagnostic data were available were successfully captured using the camera. Sixteen of 18 melanomas, and 89% of pigmented lesions overall, were correctly classified by the image analysis system, compared with 83% based on clinical gradings of lesion characteristics. CONCLUSION: Computer image analysis has the potential to provide a valuable diagnostic aid that could enable clinicians to make highly sensitive and specific diagnoses of early, curable melanoma.

Adolescent↗
PubMed1994

Comparability of naevus counts between and within examiners, and comparison with computer image analysis.

In the course of an investigation of melanocytic naevus development in Queensland, Australia, whole-body naevus counts of 66 adolescents were performed separately by two nurse examiners on two occasions on average 4 weeks apart. There was good agreement between the two examiners for counts of total naevi on the whole body (intra-class correlation coefficient = 0.96) and at selected subsites (face, neck, back, upper arms, lower arms). Agreement was lower when raised naevi only were counted (0.83). Intra-examiner repeatability was high for both nurses, particularly for the more experienced examiner (intra-class correlation coefficients = 0.98 and 0.91 for total naevi on the whole body), and was consistently better when all naevi were counted rather than naevi of a particular size. Independent counts of naevi on the back using a computer imaging technique were reproducible (intra-class correlation coefficient = 0.92), but showed only moderate agreement with counts by the nurse examiners. Overall, these results demonstrate high comparability of naevus counts between and within similarly trained examiners. They do not support the common practice in epidemiological studies of restricting counts to naevi larger than 2 mm, or of counting raised naevi only.

Adolescent↗
PubMed1990

Design, synthesis, and 5-lipoxygenase-inhibiting properties of 1-thio-substituted butadienes.

The synthesis of novel 1-thio-substituted butadienes, designed as mechanism-based 5-lipoxygenase inhibitors, is described. The structure of these compounds closely resembles a proposed high-energy intermediate during the lipoxygenation of arachidonic acid. They demonstrate 5-lipoxygenase inhibition in vitro and in vivo. The most potent compound is 15a with an IC50 of 1.8 microM in vitro. LTC4 release was inhibited by 80% after intraperitoneal administration of 15c at a dose of 2 mg/kg.

Animals↗