Energy metabolism during microsurgical transfer of human skeletal muscle assessed by high-pressure liquid chromatography and by 31P-nuclear magnetic resonance.

The effect of ischaemia and reperfusion on human skeletal muscle was studied during free vascularised muscle transfer. Muscle biopsy specimens were taken from patients having microsurgical muscle transfer, 18 cases (17 patients; 12 men, 5 women). The biopsies were taken three times: before transfer of the muscle (control), at maximum ischaemic time, and one hour after revascularisation. The biopsy specimens were analysed for purine nucleotides, by high-pressure liquid chromatography (HPLC), and by nuclear magnetic resonance (NMR) at 500 MHz. Phosphocreatine (PCr) recovered only partially (79%) and adenosine triphosphate (ATP) did not differ significantly from normal control after revascularisation and a mean ischaemic time of 114 minutes. NMR measurements showed an accumulation of glucose-6-phosphate (G-6-P) during the ischaemic period, indicating anaerobic metabolism. After three hours of ischaemia and one hour of reperfusion the PCr recovery was less than 60% (r = 0.7). The results confirm those of previous animal studies, which set three hours normothermic ischaemia as a safe limit for tissue preservation when transferring skeletal muscle. Longer ischaemic times may cause serious postoperative healing problems and reduced muscle function.     

Quantitative measurement of regional lung ventilation using 3He MRI.

A new strategy for a quantitative measurement of regional pulmonary ventilation using hyperpolarized helium-3 (3He) MRI has been developed. The method employs the build-up of the signal intensity after a variable number of (3)He breaths. A mathematical model of the signal dynamics is presented, from which the local ventilation, defined as the fraction of gas exchanged per breath within a given volume, is calculated. The model was used to create ventilation maps of coronal slices of guinea pig lungs. Ventilation values very close to 1 were found in the trachea and the major airways. In the lung parenchyma, regions adjacent to the hilum showed values of 0.6-0.8, whereas 0.2-0.4 was measured in peripheral regions. Monte Carlo simulations were used to investigate the accuracy of the method and its limitations. The simulations revealed that, at presently attainable signal-to-noise ratios, the ventilation parameter can be determined with a relative uncertainty of <5% over a wide range of values.     

An examination of the relationships among interpersonal stress, morale and academic performance in male and female medical students

Conflicts between medical students and persons involved in their clinical training are a common, yet little studied, source of stress for students. The study reported in this paper examined the relationships between interpersonal stress, specific to training, and measures of students' morale and academic performance during the clinical phase of medical education. The results show that although interpersonal stress was inversely related to morale in both male and female students, the relationship was stronger for females. Morale and interpersonal stress variables strongly predicted the academic performance of female students, as measured by the grades they received in clinical clerkships and their scores on the Part II examination of the National Board of Medical Examiners. The results for males were less clear-cut, as the predictor variables were significantly related to only one of the two performance measures. These findings are consistent with the view that non-cognitive factors have particular relevance for the performance of female medical students.     

Shape of the neuroretinal rim and position of the central retinal vessels in glaucoma.

Glaucomatous neuroretinal rim loss can occur in a sequence of sectors with the temporal inferior disc sector as the first and the nasal superior disc sector as the last to be affected. This study evaluated whether the position of the central retinal vessel trunk is correlated with this pattern of glaucomatous rim loss. Morphometrically stereo colour optic disc photographs of 157 glaucomatous eyes and 67 normal eyes were checked. In the normal and glaucomatous eyes, the central retinal vessel trunk was located eccentrically in the upper nasal quadrant of the optic disc. Taking into account the vertically oval disc shape, the distance to the central vessel trunk was largest for the temporal inferior disc region and shortest for the nasal superior disc area. An abnormal form of the glaucomatous neuroretinal rim was found in eyes with an atypical location of the retinal vessel trunk. Also in these glaucomatous eyes, the rim loss was usually most and least marked in that sector with the longest and shortest distance, respectively, to the central retinal vessel trunk. One could infer that the sequence of rim loss in glaucoma is dependent upon the distance of the region to the central retinal vessel trunk; the further away the region from the retinal vessel trunk, the more likely it is to be affected by rim loss. This suggest that the distance from the central retinal vessels is one factor among others that is correlated with the regional vulnerability of the neuroretinal rim to the glaucomatous process.     

Induction of DNA strand breaks by ethylene oxide in human diploid fibroblasts

In vitro exposure of normal human diploid fibro-blasts (strain VH-10) to ethylene oxide (EtO) induced DNA strand breaks in the dose range of 2.5–30 mMh of EtO. Alkaline DNA unwinding (ADU), neutral filter elution (NFE), pulsed field gel electrophoresis (PFGE), and the comet assay were used to measure DNA single (SSBs) and double strand breaks (DSBs). Different induction rates of SSBs and DSBs, depending on applied method and also on treatment conditions (cells in monolayer or in suspension were used), were found. A dose-dependent increase of DNA strand breaks was found by the ADU method in the dose range of 2.5–20 mMh of EtO when treatment was performed in monolayer and in suspension. DSBs were detected by NFE only when the cells were treated with EtO in suspension (doses 10–30 mMh). The highest induction rate of DSBs (about 4 DSBs per 100 Mbp per 1 mMh of EtO) was detected in suspension with PFGE applied. We have shown that heat-labile sites are formed by EtO. Presumably, the different DSB levels detected by PFGE and NFE result from the conversion of these sites to DSBs during cell lysis at elevated temperature in the PFGE method. The results of the comet assay confirmed that apoptotic processes are not involved in the formation of DSBs in our experimental conditions (less than 1% of apoptotic cells were observed at all doses studied). Possible mechanisms for the induction of DNA strand breaks by EtO-treatment are discussed. The capacity to repair DSBs in EtO-exposed (5–7.5 mMh) cells was studied, and it was found that a considerable part of the damage (about 50%) could be repaired during 18 hr of incubation. © 1994 Wiley-Liss, Inc.     

A retrospective study on chemical and radioactive synovectomy in severe haemophilia patients with recurrent haemarthrosis

Between 1970 and 1994, 116 chemical and 90 radioactive synovectomies were performed in 107 patients with severe haemophilia and two with type 3 von Willebrand's disease. The products used were osmic acid (OA) in 100 cases, 90-Yttrium in 35 cases, 186-Rhenium in 48, 169-Erbium in two, hexacetonide triamcinolone in 16 and radioactive gold in five cases. The use of radioactive colloids is not allowed in France in patients under 15 years of age. Twenty-nine patients had more than one synovectomy per joint. All patients were evaluated for 6 months post-synovectomy, using both a clinical and a radiological score. Six months after synovectomy, a good or excellent result was obtained for 81% of the joints treated with isotopes, compared with 44% of those treated with OA, P<0.001. This superiority of isotopes over osmic acid was still observed after 6 months for the 89 joints that were re-evaluated, with follow-up ranging from 1 to 9 years. It was possible to calculate a radiological score in 84 cases. With OA the best results were from the joints with the lowest scores pre-synovectomy (<7). No correlation could be established between the clinical and the radiological scores, due to the small size of the sample. In summary: (1) chemical and radioactive synovectomy are simple and safe procedures for haemophilic arthropathy, (2) in our series, after 6 months the efficacy of isotopic synovectomy was greater than that of chemical synovectomy, and this benefit seems to persist after 6 months, and up to 9 years in the group of patients with longer-term follow-up.     

Choledocholithiasis in infants: diagnostic and therapeutic problems

During the 3-year period, January 1986 through December 1988, 7 of 24 infants evaluated for cholestatic liver disease were found to have choledocholithiasis with or without associated gallbladder disease. Five were born prematurely with associated predisposing factors, especially systemic infection and total parenteral nutrition. The clinical course varied from spontaneous recovery in two patients to ongoing liver disease requiring surgical or endoscopic intervention in five infants. Asymptomatic patients with normal liver function and persistently dilated extrahepatic biliary trees posed the most difficult therapeutic problems. Endoscopic retrograde cholangiography appeared to be an effective and rewarding therapeutic approach.     

The baby MB case: medical decision making in the context of uncertain infant suffering

The recent MB case involved a dispute between an infant's parents and his medical team about the appropriateness of continued life support. The dispute reflected uncertainty about two key factors that inform medical decision making for seriously ill infants: both the amount of pain MB experiences and the extent of his cognitive capacities are uncertain. Uncertainty of this order makes decision making in accordance with the best-interests principle very problematic. This article addresses two of the problems that cases such as that of MB pose for those charged with making medical decisions for infants. First, the question of the moral significance of the interest in avoiding pain is considered. It is claimed that this interest can be outweighed by higher-order interests such as those related to autonomy but that where such higher-order interests do not exist, the interest in avoiding pain should be prioritised. Second, the question of how to proceed in cases in which the level of pain or the extent of an infant's higher-order interests cannot be decisively established is considered. It is suggested that when genuine uncertainty over the interests of an infant exists, parental views about treatment should prevail.