Role of the medical physicist in interventional radiology

Interventional radiological procedures have significantly increased the probability for the expression of deterministic detriment to the patient. It is the responsibility of the consulting medical physicist to undertake the responsibility that (i) appropriate equipment is specified and purchased; (ii) the equipment purchased produces the best possible image quality for the minimum dose; (iii) accurate dosimetry is measured, calculated and recorded; (iv) interventional physicians and surgeons are adequately trained in the fundamental techniques that will minimize the dose to both patients and staff, while maintaining high image quality; and (v) interventional protocols, record keeping and patient follow-up, in the case of deterministic doses, are appropriately implemented.     

慢性阻塞性肺部疾病病人麻醉机械通气时通气与血流比例的定量分析

目的 应用多种惰性气体清除技术(multiple inert gas elimination technique,MIGET)的实验方法定量分析病人的自主呼吸和机械通气状态下通气与血流比例,以指导临床治疗和评价机械通气效果.方法 选择12例慢性阻塞性肺部疾病(chronic obstructive pulmonary disease,COPD)稳定期病人,ASAⅡ～Ⅲ级,拟行下肢血管手术.在麻醉前和麻醉诱导后行间歇正压通气(intermittent positive pressure ventilation,IPPV)60 min后测定MIGET和血气分析,比较两时点的差异.结果 COPD麻醉病人机械通气后PaO2明显增高(P=0.000).机械通气前后肺内分流和肺泡通气死腔比较无统计学差异.在机械通气后低通气与血流比例区域(肺灌注标准差对数logSDQ)明显增加(P=0.005).结论 COPD稳定期病人麻醉机械通气后肺内灌注分配不协调,低通气血流比例区域增加,肺内通气分布更加不均匀.通气与血流比例曲线呈现多种COPD特征模式.MIGET是一种无创且无需病人特殊配合的床旁监测方法.     

Pituitary adenylate cyclase-activating peptide (PACAP) and PACAP type 1 receptor expression in regenerating adult mouse and rat superior cervical ganglia in vitro

Pituitary adenylate cyclase-activating polypeptide (PACAP), a regulatory peptide belonging to the vasoactive intestinal peptide (VIP) family, is widely distributed in the central and peripheral nervous system. Recent studies have shown that PACAP expression is upregulated in sensory neurons in response to axonal injury. Here we report that PACAP and PACAP type 1 receptors are located in rat and mouse superior cervical ganglia (SCG). PACAP-immunoreactivity (-IR) was demonstrated in preganglionic fibers, whereas only occasional PACAP-IR cell bodies could be observed. In situ hybridization histochemistry using ³⁵S-labeled deoxyribonucleotide probes confirmed that PACAP mRNA was present only in occasional cell bodies. In contrast, PACAP type 1 receptor mRNA was expressed in virtually all cell bodies within the ganglia. After removal and culturing of the SCG for 24 h, there was a marked increase in PACAP mRNA, whilst PACAP type 1 receptor mRNA expression appeared to be downregulated in most nerve cell bodies except for a few scattered neurons displaying a strong upregulation. The total specific binding of PACAP to isolated SCG membranes as assayed by [¹²⁵I]PACAP-27 binding showed an increase in SCG cultured for 48 h. PACAP-27 neither affected axonal outgrowth from the cultured SCG nor the survival of cells within the SCG. We conclude that PACAP and PACAP receptors are rapidly upregulated in sympathetic ganglia in response to axonal injury and that PACAP may play a role during nerve regeneration.     

Detection of mutations in insulin-receptor gene in NIDDM patients by analysis of single-stranded conformation polymorphisms

We used the recently described technique of single-stranded conformation-polymorphism (SSCP) analysis to examine the insulin-receptor locus. First, the ability of the method to detect known mutations and polymorphisms in the insulin-receptor coding sequence was assessed. Regions of the insulin-receptor sequence containing 16 different nucleotide changes, 9 in patient genomic DNA and 7 as cloned cDNA in plasmids, were analyzed. All 9 patient genomic DNA mutants and 5 of 7 plasmid mutants exhibited variant SSCP patterns. To investigate the potential of the technique for screening many patients, the 5 exons that encode the tyrosine kinase domain of the insulin receptor were examined in 30 unrelated white subjects with non-insulin-dependent diabetes mellitus (NIDDM). Exons 17-21 were amplified from genomic DNA with polymerase chain reaction and subjected to SSCP analysis. Exons 19, 20, and 21 revealed no bands of aberrant migration, suggesting a high degree of conservation of these sequences. One diabetic subject had an SSCP variant in exon 18. Direct sequencing of this subject's genomic DNA revealed a heterozygous missense mutation (Lys1068----Glu1068). Five different SSCP patterns were detected in exon 17. Based on direct sequencing, these patterns were explained by combinations of three different nucleotide substitutions, two of which were common silent polymorphisms. One subject had a heterozygous missense mutation Val985---- Met985. Allele-specific oligonucleotide hybridization confirmed the presence of these mutations in the appropriate diabetic subjects and also detected the Val985 mutation in heterozygous form in 1 of 13 nondiabetic white subjects. SSCP analysis is a sensitive rapid method for screening for mutations in the insulin-receptor gene.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sustained slowing effect of lentils on gastric emptying of solids in humans and dogs.

The distal small intestine is an especially potent site for carbohydrate-triggered intestinal inhibition of gastric emptying of solids. Poorly digestible carbohydrates, such as lentils, may escape proximal absorption, travel over time to reach these inhibitory mechanisms, and slow the gastric emptying of a later meal. A slowing effect on gastric emptying may be associated with a lowering effect on postprandial glucose. The aims of this study were to determine (a) whether lentils (a poorly digestible carbohydrate) vs. bread (an easily digestible carbohydrate) eaten as a premeal (with equal amounts of carbohydrates) slow the gastric emptying of a second solid meal taken 4.0-4.5 hours later and (b) whether a slowing effect on the gastric emptying of the second meal is associated with a lower postprandial glucose response. We found that in 7 dogs and 10 humans, gastric emptying of the second meal was delayed after a lentil premeal compared with a bread premeal. However, there was no difference in the glucose response to the second meal under the two conditions.