Measurement of starch fermentation in the human large intestine

Starch, not fibre, is probably the major substrate for fermentation in the human colon. However, quantitating the amount of starch that resists pancreatic amylase and thus escapes digestion in the small bowel is difficult. A number of techniques have been employed in man and are reviewed here, including direct intubation of the ileum, the ileostomy model, and breath studies. The results of a series of studies of the digestion of starch from potato and banana are reported. When fed to ileostomy patients, 3% of hot potato starch and 12% of cold potato starch were resistant to digestion, as was 75% of banana starch. In feeding experiments with healthy volunteers none of the starch was recoverable in faces, indicating its complete fermentation in the colon. Breath H2 measurements after test meals of these starches indicated that only 2-5% of potato starch and 7-12% of banana starch was fermented. A single blood acetate measurement timed to coincide with peak breath H2 was not useful. However, a number of problems with breath H2 studies are discussed, and it is suggested that either ileal intubation or the ileostomy model are the most reliable techniques presently available, with serial blood acetate determinations also potentially valuable. Overall on Western diets, approximately 10% of all starch is probably resistant starch.     

A SURVEY OF SURGICAL SHOCK WITH SPECIAL REFERENCE TO FLUIDS,ELECTROLYTES AND METABOLITES

In clinical evaluation and analysis of 85 consecutive carotid endarterectomies in 74 consecutive patients, the operation was shown to be an effective and safe method of treating cerebral vascular insufficiency. It must be properly timed and performed, and excellent results may be expected, particularly in comparison with nonoperatively treated patients with the same disease.     

Regulation of the APC and the exit from mitosis

The events of late mitosis, from sister-chromatid separation to cytokinesis, are governed by the anaphase-promoting complex (APC), a multisubunit assembly that triggers the ubiquitin-dependent proteloysis of key regulatory proteins. An intricate regulatory network governs APC activity and helps to ensure that late mitotic events are properly timed and coordinated.     

Nomifensine chronopharmacology, schedule-shifts and circadian temperature rhythms in di-suprachiasmatically lesioned rats--modeling emotional chronopathology and chronotherapy

Some emotional disorders are associated with alterations of biological rhythm characteristics ('echronism'). Chronotherapy aims empirically to 1. optimize the kind and timing of conventional psychopharmacologic treatment and, need be, to use such old or new molecules in the rational endeavor to 2. correct (disease-determining) rhythm alteration directly. With respect to the first aim, a reduction by timing of undesired pharmacodynamic effects, as well as an amplification of empirically desired ones, can be dramatically illustrated by circadian rhythms in tolerance to many drugs affecting the central nervous system of rodents. A more rational approach is aimed at correcting ecchronism. The new antidepressant drug, nomifensine, achieves this task in rats with bilateral suprachiasmatic lesions, exhibiting in the telemetered core temperature an echronism of varying degrees. In this model system for the chronobiotic treatment of ecchronism, the properly timed administration of nomifensine speeds the adjustment of bilaterally (suprachiasmatically) lesioned rats to a shift in the synchronizing light-dark schedule. With methodologic provisions, notably for treatment timed by pertinent marker rhythms, nomifensine deserves clinical tests in psychochronotherapy.     

Urinary Calculi and Ulcerative Colitis

A survey of 458 patients treated for ulcerative colitis either medically or surgically by colectomy and the establishment of an ileostomy has provided further evidence that in Australia at least there is a significant association between ulcerative colitis and urinary calculi. The actual risk to the unoperated patient is not particularly high but is in the vicinity of 4%. The survey further confirms that the risk continues after colectomy and ileostomy, when the overall incidence of stones is roughly doubled. Finally, suggestive though admittedly somewhat inconclusive evidence supports the proposition that uric acid stones are more common in this group of patients.     

The link in Linking

We present 2 cases of the slow-fast form of AVNRT with initially narrow QRS complexes followed by sudden unexpected transition to persistently wide QRS complexes due to aberrant intraventricular conduction. Introduction of a properly timed extrastimulus in one case and critical oscillations in cycle length due to short-long coupling in the second case set the stage for the initial bundle branch block. However, persistence of the aberrancy pattern once the initial event abated was maintained by the “linking” phenomenon. Delayed, retrograde concealed activation from the contralateral bundle branch perpetuated the initial bundle branch block.     

The origin recognition complex functions in sister-chromatid cohesion in Saccharomyces cerevisiae

High-fidelity chromosomal segregation requires the properly timed establishment of sister-chromatid cohesion mediated by the Cohesin complex, and its resolution at the metaphase-to-anaphase transition. We have examined cell-cycle progression in a yeast strain from which the origin recognition complex protein Orc2 was depleted after the assembly of prereplication complexes. We find that Orc2 depletion causes a delay in progression through mitosis, reflecting activation of both the DNA-damage and Mad2-spindle checkpoints. Surprisingly, sister-chromatid cohesion is impaired in Orc2-depleted cells, although Cohesin subunits are properly associated with chromatin. Reexpression of Orc2 in late G2/M phase restores chromatid cohesion. Finally, the targeting of Orc2 to a specific chromosomal locus suppresses premature sister-chromatid separation locally in a temperature-sensitive cohesin mutant. We conclude that ORC mediates sister-chromatid interaction on a pathway that is additive with Cohesin-mediated pairing.     

Generative models of rich clubs in Hebbian neuronal networks and large-scale human brain networks

Rich clubs arise when nodes that are ‘rich’ in connections also form an elite, densely connected ‘club’. In brain networks, rich clubs incur high physical connection costs but also appear to be especially valuable to brain function. However, little is known about the selection pressures that drive their formation. Here, we take two complementary approaches to this question: firstly we show, using generative modelling, that the emergence of rich clubs in large-scale human brain networks can be driven by an economic trade-off between connection costs and a second, competing topological term. Secondly we show, using simulated neural networks, that Hebbian learning rules also drive the emergence of rich clubs at the microscopic level, and that the prominence of these features increases with learning time. These results suggest that Hebbian learning may provide a neuronal mechanism for the selection of complex features such as rich clubs. The neural networks that we investigate are explicitly Hebbian, and we argue that the topological term in our model of large-scale brain connectivity may represent an analogous connection rule. This putative link between learning and rich clubs is also consistent with predictions that integrative aspects of brain network organization are especially important for adaptive behaviour.     

RecA protein of Escherichia coli and chromosome partitioning

Escherichia coli cells deficient in RecA protein frequently contain an abnormal number of chromosomes after completion of ongoing rounds of DNA replication. This suggests that RecA protein may be required for correct timing of initiation of DNA replication; however, we show here that initiation of DNA replication is properly timed in recA mutants. We also find that more than 10% of recA mutant cells contain no DNA. These anucleate cells appear to arise from partitioning of all the DNA into one daughter cell and no DNA into the other daughter cell. Based on these and previously published results, we propose that RecA protein is required for equal partitioning of chromosomes into the two daughter cells.     

蜥脚类骨质尾锤之发现

自贡大山铺恐龙化石坑中出土的李氏蜀龙(Shunosaurus lii)和天府峨眉龙(Omeisaurustianfuensis)均发现由尾端脊椎愈合膨大而成之纺锤形骨质尾锤。这一特征在蜥脚类中尚属首次记述。骨质尾锤是一种适应陆地生活之特殊构造。它作为一种防御武器,主要起防卫身体的作用。它的存在说明R.T.Bakker提出的蜥脚类是一类营陆地生活的恐龙的观点是正确的。     

拟南芥春化作用相关基因FLC的表达调控及天然早花突变体的研究进展

植物开花是从营养生长到生殖状态的重要发育转变,是多种内在因子和环境因素共同作用的结果。在拟南芥开花调控网络中,开花抑制基因FLC处于枢纽地位。FLC的表达受许多来自环境和生长发育的信号调控,主要包括：PAF1复合体、SWR1复合体成员,FRI依赖途径、自主途径和春化作用途径基因。本文主要综述了影响FLC表达的春化相关基因及天然早花突变体的研究进展,并根据最新的研究成果提出该研究领域的研究方向和重点。     

The sigmaE and Cpx regulatory pathways: overlapping but distinct envelope stress responses.

The Cpx and sigmaE extracytoplasmic stress responses sense and respond to misfolded proteins in the bacterial envelope. Recent studies have highlighted differences between these regulatory pathways in terms of activating signals, mechanisms of signal transduction and the nature of the responses. Cumulatively, the findings suggest distinct physiological roles for these partially overlapping envelope stress responses. The sigmaE pathway is essential for survival and is primarily responsible for monitoring and responding to alterations in outer membrane protein folding. Mounting evidence suggests that the Cpx regulon may have been adapted to ensure properly timed expression and assembly of adhesive organelles.     

Proctocolectomy without ileostomy for ulcerative colitis.

An operation has been developed that permits total removal of all disease-prone mucosa in ulcerative colitis but avoids the need for a permanent ileostomy. The colon and upper half of the rectum are excised and the remaining inflamed mucosa is stripped from the rectal stump down to the dentate line of the anal canal. A pouch is fashioned from a triplicated loop of terminal ileum. This is drawn down through the denuded rectum and an anastomosis created, via the per-anal approach, between the ileum just distal to the pouch and the mid-anal canal. A temporary ileostomy is made. Out of eight patients so treated, five were available for assessment, and four of them were highly satisfied with the result in improved health and function. The remaining three were awaiting closure of their ileostomies.     

The marginal valuation of fertility

Substantial theoretical and empirical evidence demonstrates that fertility entails economic, physiological, and demographic trade-offs. The existence of trade-offs suggests that fitness should be maximized by an intermediate level of fertility, but this hypothesis has not had much support in the human life-history literature. We suggest that the difficulty of finding intermediate optima may be a function of the way fitness is calculated. Evolutionary analyses of human behavior typically use lifetime reproductive success as their fitness criterion. This fitness measure implicitly assumes that women are indifferent to the timing of reproduction and that they are risk-neutral in their reproductive decision-making. In this paper, we offer an alternative, easily-calculated fitness measure that accounts for differences in reproductive timing and yields clear preferences in the face of risky reproductive decision-making. Using historical demographic data from a genealogically-detailed dataset from 19th century Utah, we show that this measure is highly concave with respect to reproductive effort. This result has three major implications: (1) if births are properly timed, a lower-fertility reproductive strategy can have the same fitness as a high-fertility strategy, (2) intermediate optima are far more likely using fitness measures that are strongly concave with respect to effort, (3) we expect mothers to have strong investment preferences with respect to the risk inherent in reproduction.     

Enzyme histochemistry of the spinal cord after experimental transection (Th 9) in the cat

Subpial complete resection of a 10 mm segment of the spinal cord at Th 9 was performed in 9 adult cats. Topographic enzyme histochemical investigations of the terminal clubs were performed after different survival times after transection in 7 cats and three days after a subsequent one-week-delayed autologous sciatic grafting procedure in the remaining two cats. For acid phosphatase (ACP), the count of active terminal clubs was high (200 per m2) from 12 hours until day 3 after transection. Then the count of active terminal clubs decreased to a low level (20 per m2) and remained the same until day 14. Removal of necrotic tissue and subsequent grafting with autologous sciatic nerve did not change these findings. For succinate dehydrogenase (SDH), the numbers of terminal clubs showed the same pattern at a lower level. The SDH defined terminal clubs were smaller than the ACP ones. The length of the SDH positive area decreased after 7 days while the ACP positive area remained the same until day 14. The SDH active terminal clubs are overgrown by the ACP positive terminal clubs, after the 7th day. Considering that SDH is linked to constructive activity in mitochondria and ACP to destructive activity in lysosomes, this phenomenon might be responsible for the termination of the capacity of the spinal cord tissue to regenerate.     

A tribute to John Gibbon

This article provides an overview of the published research of John Gibbon. It describes his experimental research on scalar timing and his development of scalar timing theory. It also describes his methods of research which included mathematical analysis, conditioning methods, psychophysical methods and secondary data analysis. Finally, it describes his application of scalar timing theory to avoidance and punishment, autoshaping, temporal perception and timed behavior, foraging, circadian rhythms, human timing, and the effect of drugs on timed perception and timed performance of Parkinson's patients. The research of Gibbon has shown the essential role of timing in perception, classical conditioning, instrumental learning, behavior in natural environments and in neuropsychology.     

Effect of progesterone treatment near term on the onset of labour in rats

The effect of systematically delayed progesterone treatment on the onset of labour was examined in 45 pregnant rats. Measurement of progesterone (P) and prostaglandin F (PGF) in uterine vein plasma and uterine tissue before and during spontaneous labour or during prolonged pregnancy showed that the control animals exhibited the expected P-withdrawal (Pw) prior to spontaneous labour, however, properly timed P-treatment predictably prevented Pw and labour. When P was administered 11.7 +/- 2.8 hours before spontaneous labour, the animals delivered normally, despite increased plasma and tissue P-levels. These observations show that P-concentration cannot be equated to P-action.     

Human ileostomy glycoproteins as a model for small intestinal mucus to investigate adhesion of probiotics

Human ileostomy glycoproteins were used as a model for small intestinal mucus to investigate the adhesion of 12 Lactobacillus strains, one Lactococcus strain and one Propionibacterium strain, Both probiotic and dairy strains were tested. Adhesive and non-adhesive Escherichia coli strains were used as controls. All the strains were also tested for their adhesion to polystyrene. Adhesion to ileostomy glycoproteins and to polystyrene varied significantly among the strains tested. Lactobacillus rhamnosus (human isolate), Lactobacillus GG, Lact. acidophilus 1 and P. freudenreichii adhered to ileostomy glycoproteins. Adhesion was concentration-dependent and the most adhesive strains were able to saturate the substratum. These results indicate that human ileostomy glycoproteins can be used as a model system to select potential probiotic strains to complement the adhesion test with intestinal cell lines.