Effects of isoflurane, sevoflurane, and halothane on myofilament Ca2+ sensitivity and sarcoplasmic reticulum Ca2+ release in rat ventricular myocytes

BACKGROUND: The aim of this study was to describe and compare the effects of isoflurane, sevoflurane, and halothane at selected concentrations (i.e., concentrations that led to equivalent depression of the electrically evoked Ca2+ transient) on myofilament Ca2+ sensitivity, sarcoplasmic reticulum (SR) Ca2+ content, and the fraction of SR Ca2+ released during electrical stimulation (fractional release) in rat ventricular myocytes. METHODS: Single rat ventricular myocytes loaded with fura-2 were electrically stimulated at 1 Hz, and the Ca2+ transients and contractions were recorded optically. Cells were exposed to each anesthetic for 1 min. Changes in myofilament Ca2+ sensitivity were assessed by comparing the changes in the Ca2+ transient and contraction during exposure to anesthetic and low Ca2+. SR Ca2+ content was assessed by exposure to 20 mm caffeine. RESULTS: Isoflurane and halothane caused a depression of myofilament Ca2+ sensitivity, unlike sevoflurane, which had no effect on myofilament Ca2+ sensitivity. All three anesthetics decreased the electrically stimulated Ca2+ transient. SR Ca2+ content was reduced by both isoflurane and halothane but was unchanged by sevoflurane. Fractional release was reduced by both isoflurane and sevoflurane, but was unchanged by halothane. CONCLUSIONS: Depressed myofilament Ca2+ sensitivity contributes to the negative inotropic effects of isoflurane and halothane but not sevoflurane. The decrease in the Ca2+ transient is either responsible for or contributory to the negative inotropic effects of all three anesthetics and is either primarily the result of a decrease in fractional release (isoflurane and sevoflurane) or primarily the result of a decrease in SR Ca2+ content (halothane).     

Polymorphisms and circulating levels in the insulin-like growth factor system and risk of breast cancer: a systematic review.

We reviewed all English-language articles on associations among circulating levels of the insulin-like growth factors (IGF) and their binding proteins (IGFBP), polymorphisms in their genes, and breast cancer risk. In premenopausal women, five of eight IGF-I studies and four of six IGFBP-3 studies of circulating levels found that women in the highest quantile had more than twice the risk of developing breast cancer of those in the lowest, although in some this effect was only apparent at young ages. In postmenopausal women, however, there was no consistent effect. A simple sequence length polymorphism 1 kb 5' to IGF-I was examined in relation to circulating levels of IGF-I (12 studies) or breast cancer risk (4 studies), but there was no convincing evidence of any effect. For an A/C polymorphism 5' to IGFBP-3, all three studies were consistent with a modest effect on circulating levels, but no evidence of a direct effect on breast cancer risk was seen in the only relevant study. Variation within the reference range of IGF-I and IGFBP-3 may confer only modest increases in breast cancer risk, and any single polymorphism may only account for a small proportion of that variation. Nevertheless, population attributable fractions for high circulating levels of IGF-I and IGFBP-3 and for common genetic variants could be substantial. Further large studies, or combined analysis of data from existing studies, are needed to quantify these effects more precisely.     

Post traumatic laryngeal incompetence

Self-inflicted laryngeal injuries are rare. This is a case of attempted suicide with a knife. The patient was brought into A&E and initial attempts at repair of the laryngo-skeletal structures were performed Later it became evident that the patient had an insensate hypofunctioning larynx. We present a technique aimed at rehabilitating the poorly functioning, incompetent larynx without the necessity for a permanent tracheostomy or laryngectomy. A single surgical procedure combining a cricopharyngeal myotomy, an anterior hyoid suspension and vocal fold angmentations was performed in an attempt to avoid a laryngectomy in non-malignant pathology. The long-term results of this surgery would need to be subjected to further evaluation.     

Soybean oil emulsion administration during parenteral nutrition in the preterm infant: effect on essential fatty acid, lipid, and glucose metabolism

To examine the effect of a soybean oil emulsion on essential fatty acid, lipid, and glucose metabolism, preterm infants were randomized to receive 0.5 g/kg/d lipid for 5 days (n = 10, group 1) or 0.5 increased to 2.0 g/kg/d over 5 days (n = 11, group 2). Triene/tetraene ratios did not change in group 1, but decreased in group 2. In both groups, plasma phospholipid linoleate (percent and micrograms per milliliter) increased, the increase being greater in group 2. In both groups, percent content of arachidonate and 5,8,11-eicosatrienoate decreased, and that of oleate remained unchanged. In contrast, absolute content of arachidonate and oleate tended to increase, and that of 5,8,11-eicosatrienoate remained unchanged. At a lipid intake of 0.5 g/kg/d, no infants had hyperlipemia. When lipid intake exceeded 1.0 g/kg/d, the frequency of hypertriglyceridemia (triglycerides greater than 200 mg/dL) and free fatty acidemia, with the free fatty acid/molar albumin ratio exceeding 6:1, increased. Plasma glycerol increased slightly, but was substantially less than the rise in enzymatically determined triglycerides. Hyperglycemia was self-limiting and did not require alteration in dextrose intake. Thus, (1) infusion of a soybean oil emulsion at 0.5 to 2.0 g/kg/d maintains essential fatty acid status and phospholipid arachidonate concentrations; (2) significant hyperlipemia occurs when lipid intake exceeds 1.0 g/kg/d; (3) hyperglycemia associated with lipid infusion tends to be self-limiting and may not require alteration in lipid or dextrose intake; and (4) enzymatically determined triglycerides may be used to monitor lipid tolerance, provided that allowance is made for a small but systematic overestimation resulting from the rise in plasma glycerol.     

Acute gouty arthritis without urate crystals identified on initial examination of synovial fluid

Nine patients who ultimately proved to have acute gouty arthritis did not have urate crystals demonstrable by compensated polarized light in the first joint fluid aspirated despite leukocyte counts as high as 100,000/mm³. In 6 cases crystals were found in fluid from the same joint 5 hours to 1 day later. Factors that might explain the difficulty in identifying crystals include aspiration of the wrong site because diffuse swelling obscured predominant involvement of a bursa or adjacent small joint, loculation within a joint, crystal dissolution leaving only tiny birefringent chunks, and inexpert or insufficient search. Some cases remain without any tentative explanation. The possibility of acute gouty arthritis should not be excluded if crystals are not demonstrable in the first search of joint fluid. Repeated searches for typical monosodium urate crystals may be required for diagnosis.     

Nursing concerns for patients undergoing mastectomy

The author describes an outline for a plan of care nurses could use in caring for patients undergoing a mastectomy. Needs of patients are categorized from the time of discovery of the lump until after mastectomy. Personal perceptions are documented; methods are explored for nurses to expand their knowledge.     

Ethanol preference in C57BL/6 and BALB/c mice at three ages and eight ethanol concentrations

Abstract

C57BL/6 and BALB/c mice were tested for ethanol preference at three ages (7–9 mo., 14–16 mo., 22–24 mo.). Eight ethanol concentrations (4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%) were used. A reduction in ethanol preference with increasing age was seen in the C57BL/6 mice, but not in the BALB/c animals. For C57BL/6 mice the largest difference in ethanol preference occurred between the 10% and 18%, ethanol solutions. It was found that the ethanol preference of the 14–16 mo. C57BL/6 mice was similar to the 7–9 mo. old C57BL/6 mice at the first 5 concentrations. For the remaining concentrations the 14–16 mo. mice more closely resembled the 22–24 mo. mice in ethanol preference. The results of this study suggested that increased age does not simply result in a reduction in ethanol preference, but is a function of the genotype and concentration of the ethanol solution.     

Relationship of age and hypertension to neuropsychological test performance

Young adult (X = 29) and middle aged (X = 50) hypertensive and normotensive subjects were compared with respect to seven neuropsychological test scores derived from tests on the Halstead-Reitan battery. Age main effects, with inferior performance for the middle aged subjects, were observed for the localization and time portions of the Tactile Performance Test (TPT) and for the Trail Making A test. The multivariate age effect was significant for the composite of seven scores. A multivariate blood pressure main effect was obtained and main effect blood pressure was significant for the category test; hypertensives made more errors than normotensives. A blood pressure by age interaction was observed for finger tapping scores and the TPT-Memory scores with larger differences between hypertensives and normotensives for the younger than for the middle aged group. Results were discussed in terms of previous studies of age and hypertension with the WAIS, the Primary Mental Abilities Test and serial reaction time measures. The poor prediction of hypertensive status from individual neuropsychological test scores was emphasized and readers were cautioned not to conclude that essential hypertensives, as a group, can be characterized as brain damaged.