Biomedical subjects

G J Kost

Publications and source records attributed to G J Kost.

60 records · Page 4Linked to original sources

PubMed1982

A comparison of fiber types and measurement techniques in the medial gastrocnemius and soleus muscles of the rabbit.

Medial gastrocnemius (MG) and soleus (S) histochemical fiber type profiles were determined in female albino rabbits (n = 5). The fiber composition of the central S was 93.5 +/- 12.7 S.D.% slow-twitch oxidative (STO), and 6.5 +/- 12.7% fast-twitch oxidative glycolytic (FTOG). No fast-twitch glycolytic (FTG) fibers were found in any of the S muscles. The S FTOG fiber percentage varied from a minimum of 0% to a maximum of 29% in different rabbits. The composition of the central MG was 22.1 +/- 2.0% STO, 28.8 +/- 4.6% FTOG, 43.9 +- 3.5% FTG, and 5.2 +/- 2.5% unidentified fibers. In the MG the STO fiber percentage increased anteriorly, while the FTG fiber percentage increased posteriorly. Two methods were employed to determine fiber diameters. Using the mean of orthogonal diameters method, we found central S diameters to be 74.6 +/- 5.1 S.D. micrometers for STO, ad 67.7 +/- 7.9 micrometers for FTOG fibers. Diameters for the central MG were 62.1 +/- 7.2 micrometers for STO, 66.1 +/- 9.4 micrometers for FTOG, 95.9 +/- 9.3 micrometers for FTG, and 83.3 +/- 9.1 micrometers for unidentified fibers. Fiber diameters calculated by the mean of orthogonal diameters method were for the S, 1.16 +/- 0.01, and for the MG, 1.21 +/- 0.01, times larger than those obtained using the "smallest diameter" (maximum minor diameter) technique. The relationship between these measurement parameters varied in the different muscles due to fiber shape variation. In the central S, STO fibers occupied 94.6%, and FTOG, 5.4% of the cross sectional area, using areas derived from the mean of orthogonal diameters measurements. In the central MG, the relative areas were 13.2% for STO, 19.6% for FTOG, 61.6% for FTG, and 5.6% for unidentified fibers. Relative area calculations were comparable using both of the measurement methods. Therefore, relative area comparisons tend to discount variations introduced by different measurement techniques.

Adenosine Triphosphatases↗

PubMed1982

Unpredictable fluctuations in transcutaneous pCO2 from capillary blood gas determinations.

Transcutaneous pCO2 electrode response time was optimized by use of a new electrode filling solution composed of NaCl/NaHCO3 electrolyte buffer (100 and 20 mmol/L, respectively) in an equivolume mixture of glycerol and water. The 95% response time to a step change in pCO2 was 49.9 +/- 2.8 s (mean +/- SD) when there was no spacer between the membrane and glass of the electrode. Use of this filling solution during monitoring of severely ill premature infants with cardiopulmonary disease allowed identification of large, unpredictable transient changes in transcutaneous pCO2, and therefore presumably in arterial pCO2, that occurred during capillary blood gas sampling. The changes, which occurred in 19 of 20 samplings, ranged from -1.06 + 2.53 kPa (-8 to +19 Torr). The maximum relative change observed was +29%. These results indicate that the standard protocol for capillary blood collection induces significant transient fluctuations in blood gas tensions. We believe these fluctuations decrease the reliability of capillary pCO2 values for use in clinical management in patient populations similar to ours.

Buffers↗

PubMedDate not supplied

A new variant of late-onset myophosphorylase deficiency.

McArdle disease classically presents in childhood or adolescence. Rarely does it become symptomatic for the first time in late adulthood, with the onset of progressive muscle wasting and weakness. Our patient is unusual in that despite a life of physical vigor, she developed immobilizing cramps, stiffness, and muscle swelling abruptly at age 60. She had no previous symptoms of muscle disease. The diagnosis was indicated by the ischemic forearm test, which produced muscle contracture and no rise in venous lactate levels, and confirmed by histochemical, electrophoretic, and biochemical studies that showed complete absence of myophosphorylase. This case defines a new variant of the late-onset type and raises important questions about compensatory mechanisms, inheritance patterns, and etiological factors in myophosphorylase deficiency.

Age Factors↗

PubMedDate not supplied

Discrimination and other statistical intervals for the interpretation of in vivo patient monitoring data.

A calibration line is used to define the relationship between a new clinical technique and a standard in vitro laboratory methodology. Discrimination intervals quantify the reliability of inverse estimates obtained from the calibration line. Applied to transcutaneous PCO2 monitoring, a new in vivo measurement, discrimination intervals for inverse estimates of arterial PCO2 range in size from 10 to 50 torr (1.33-6.67 kPa), or more, depending on the values of statistical parameters selected. Discrimination interval analysis shows that the inverse estimates are more reliable near the means. Also, it indicates that the primary value of transcutaneous PCO2 monitoring lies not in providing accurate inverse estimates of arterial PCO2, but instead, in monitoring short-term clinical trends.

Biometry↗

PubMedDate not supplied

NMRES: an artificial intelligence expert system for quantification of cardiac metabolites from 31phosphorus nuclear magnetic resonance spectroscopy.

The application of high-resolution 31Phosphorus Nuclear Magnetic Resonance (31P NMR) Spectroscopy in biology and medicine has provided new insights into biochemical processes and also a unique assessment of metabolites. However, accurate quantification of biological NMR spectra is frequently complicated by: (a) non-Lorentzian form of peak lineshapes, (b) contamination of peak signals by neighboring peaks, (c) presence of broad resonances, (d) low signal-to-noise ratios, and (e) poorly defined sloping baselines. Our objectives were to develop an expert system that captures and formalizes 31P NMR spectroscopists' expert knowledge, and to provide a reliable, efficient, and automated system for the interpretation of biological spectra. The NMR Expert System (NMRES) was written in the C and OPS5 programming languages and implemented on a Unix-based (Ultrix) mainframe system with XWindows bit-map graphics display. Expert knowledge was acquired from NMR spectroscopists and represented as production rules in the knowledge base. A heuristic weights method was employed to determine the confidence levels of potential peaks. Statistical and numerical methods were used to facilitate processing decisions. NMR spectra obtained from studies of ischemic neonatal and immature hearts were used to assess the performance of the expert system. The expert system performed signal extraction, noise treatment, resonance assignment, intracellular pH determination, and metabolite intensity quantitation in about 10 s per 4 KB (kilobyte) spectrum. The peak identification success rate was 98.2%. Peak areas and pH estimated by the expert system compared favorably with those determined by human experts. We conclude that the expert system has provided a framework for reliable and efficient quantification of complex biological 31P NMR spectra.

Artificial Intelligence↗

PubMedDate not supplied

Optimizing point-of-care testing in clinical systems management.

The goal of improving medical and economic outcomes calls for leadership based on fundamental principles. The manager of clinical systems works collaboratively within the acute care center to optimize point-of-care testing through systematic approaches such as integrative strategies, algorithms, and performance maps. These approaches are effective and efficacious for critically ill patients. Optimizing point-of-care testing throughout the entire health-care system is inherently more difficult. There is potential to achieve high-quality testing, integrated disease management, and equitable health-care delivery. Despite rapid change and economic uncertainty, a macro-strategic, information-integrated, feedback-systems, outcomes-oriented approach is timely, challenging, effective, and uplifting to the creative human spirit.

Clinical Laboratory Information Systems↗